Article

Kastl L, Brown I, Schofield ACmiRNA-34a is associated with docetaxel resistance in human breast cancer cells. Breast Cancer Res Treat 131: 445-454

March 2011
Breast Cancer Research and Treatment 131(2):445-54

March 2011
131(2):445-54

DOI:10.1007/s10549-011-1424-3

Source
PubMed

Authors:

Iain Brown

NHS Grampian

Docetaxel is a chemotherapy drug to treat breast cancer, however as with many chemotherapeutic drugs resistance to docetaxel occurs in 50% of patients, and the underlying molecular mechanisms of drug resistance are not fully understood. Gene regulation through microRNAs (miRNA) has been shown to play an important role in cancer drug resistance. By directly targeting mRNA, miRNAs are able to inhibit genes that are necessary for signalling pathways or drug induced apoptosis rendering cells drug resistant. This study investigated the role of differential miRNA expression in two in vitro breast cancer cell line models (MCF-7, MDA-MB-231) of acquired docetaxel resistance. MiRNA microarray analysis identified 299 and 226 miRNAs altered in MCF-7 and MDA-MB-231 docetaxel-resistant cells, respectively. Docetaxel resistance was associated with increased expression of miR-34a and miR-141 and decreased expression of miR-7, miR-16, miR-30a, miR-125a-5p, miR-126. Computational target prediction revealed eight candidate genes targeted by these miRNAs. Quantitative PCR and western analysis confirmed decreased expression of two genes, BCL-2 and CCND1, in docetaxel-resistant cells, which are both targeted by miR-34a. Modulation of miR-34a expression was correlated with BCL-2 and cyclin D1 protein expression changes and a direct interaction of miR-34a with BCL-2 was shown by luciferase assay. Inhibition of miR-34a enhanced response to docetaxel in MCF-7 docetaxel-resistant cells, whereas overexpression of miR-34a conferred resistance in MCF-7 docetaxel-sensitive cells. This study is the first to show differences in miRNA expression, in particular, increased expression of miR-34a in an acquired model of docetaxel resistance in breast cancer. This serves as a mechanism of acquired docetaxel resistance in these cells, possibly through direct interactions with BCL-2 and CCND1, therefore presenting a potential therapeutic target for the treatment of docetaxel-resistant breast cancer.

MicroRNAs as a clue to overcome breast cancer treatment resistance

Article

Full-text available

Sep 2021
CANCER METAST REV

Breast cancer is the most frequent cancer in women worldwide. Despite the improvement in diagnosis and treatments, the rates of cancer relapse and resistance to therapies remain higher than desirable. Alterations in microRNAs have been linked to changes in critical processes related to cancer development and progression. Their involvement in resistance or sensitivity to breast cancer treatments has been documented by different in vivo and in vitro experiments. The most significant microRNAs implicated in modulating resistance to breast cancer therapies are summarized in this review. Resistance to therapy has been linked to cellular processes such as cell cycle, apoptosis, epithelial-to-mesenchymal transition, stemness phenotype, or receptor signaling pathways, and the role of microRNAs in their regulation has already been described. The modulation of specific microRNAs may modify treatment response and improve survival rates and cancer patients’ quality of life. As a result, a greater understanding of microRNAs, their targets, and the signaling pathways through which they act is needed. This information could be useful to design new therapeutic strategies, to reduce resistance to the available treatments, and to open the door to possible new clinical approaches.

Restoring microRNA-34a overcomes acquired drug resistance and disease progression in human breast cancer cell lines via suppressing the ABCC1 gene

Article

Full-text available

Dec 2023
BREAST CANCER RES TR

Purpose Breast cancer is one of the leading types of cancer diagnosed in women. Despite the improvements in chemotherapeutic cure strategies, drug resistance is still an obstacle leading to disease aggressiveness. The small non-coding RNA molecules, miRNAs, have been implicated recently to be involved as regulators of gene expression through the silencing of mRNA targets that contributed to several cellular processes related to cancer metastasis. Hence, the present study aimed to investigate the beneficial role and mechanism of miRNA-34a-based gene therapy as a novel approach for conquering drug resistance mediated by ATP-binding cassette (ABC) transporters in breast cancer cells, besides exploring the associated invasive behaviors. Material and Methods Bioinformatics tools were used to predict miRNA ABC transporter targets by tracking the ABC transporter pathway. After the establishment of drug-resistant breast cancer MCF-7 and MDA-MB-231 sublines, cells were transfected with the mimic or inhibitor of miRNA-34a-5p. The quantitative expression of genes involved in drug resistance was performed by QRT-PCR, and the exact ABC transporter target specification interaction was confirmed by dual-luciferase reporter assay. Furthermore, flow cytometric analysis was utilized to determine the ability of miRNA-34a-treated cells against doxorubicin uptake and accumulation in cell cycle phases. The spreading capability was examined by colony formation, migration, and wound healing assays. The apoptotic activity was estimated as well. Results Our findings firstly discovered the mechanism of miRNA-34a-5p restoration as an anti-drug-resistant molecule that highly significantly attenuates the expression of ABCC1 via the direct targeting of its 3′- untranslated regions in resistant breast cancer cell lines, with a significant increase of doxorubicin influx by MDA-MB-231/Dox-resistant cells. Additionally, the current data validated a significant reduction of metastatic potentials upon miRNA-34a-5p upregulation in both types of breast cancer-resistant cells. Conclusion The ectopic expression of miRNA-34a ameliorates the acquired drug resistance and the migration properties that may eventually lead to improved clinical strategies and outcomes for breast cancer patients. Additionally, miRNA-34a could be monitored as a diagnostic/prognostic biomarker for resistant conditions.

Could miR-34a Inhibition be Used as a Tool to Overcome Drug Resistance in MCF-7 Cells Treated with Synthesized Steroidal Heterocycles?

Article

Full-text available

Mar 2021

Background: Progesterone derivatives have explored an improved effect on human cancer cells through combination of the explored heterocycles with progesterone moiety.miRNAs have an important role in moderating cancer cell survival, proliferation and drug resistance. The current study tested the hypothesis "whether miR-34a inhibitor has a negative impact on apoptosis and angiogenesis in MCF-7 cells treated with newly synthesized progesterone derivatives". Methods: MCF-7 cells were treated with progesterone derivatives individually and in combination with miR-34a inhibitor. miR-34a expression levels were measured in MCF-7 cells treated with progesterone derivatives using QRT-PCR. MCF-7 cells treated with progesterone derivatives individually showed increased miR-34a expression levels. miR-34a deficient cells were treated with the newly synthesized progesterone derivatives, after that, apoptotic and angiogenic gene expression levels were determined using QRT-PCR. The studied genes were as follows: apoptotic (Bcl-2, survivin, CCND1, CDC2, P53 and P21) and angiogenic (VEGF, Hif-1α, MMP-2, Ang-1, Ang-2, and FGF-1). Results: The results showed that miR-34a deficient MCF-7 cells treated with the newly progesterone derivatives still have promising effects on apoptotic and angiogenic genes. Besides, results revealed that miRNA-34a deficient MCF-7 cells exhibited improved effect of tested compounds in some apoptotic and angiogenic genes such as CDC-2, MMP-2. Conclusion: These results revealed that miR-34a inhibitor did not have remarkable negative effect on apoptosis and angiogenesis. On contrary, it showed an improved effect on some genes. And consequently, miR-34a inhibitor could be used safely as a tool to tackle drug resistance in breast cancer cells.

Novel miRNA Targets and Therapies in the Triple-Negative Breast Cancer Microenvironment: An Emerging Hope for a Challenging Disease

Article

Full-text available

Dec 2020
INT J MOL SCI

Amal Qattan

Treatment of triple-negative breast cancer (TNBC) remains challenging because of the heterogeneity of the disease and lack of single targetable driving mutations. TNBC does not rely on estrogen, progesterone or epidermal growth factor receptors and is associated with aggressive disease progression and poor prognosis. TNBC is also characterized by resistance to chemotherapeutics, and response to immunotherapies is limited despite promising results in a subset of TNBC patients. MicroRNAs (miRNAs) have emerged as significant drivers of tumorigenesis and tumor progression in triple-negative breast cancer (TNBC) and present unique opportunities to target various components of the TNBC microenvironment for improved efficacy against this difficult to treat cancer. Effects of miRNAs on multiple targets may improve response rates in the context of this genetically and biologically heterogeneous disease. In this review, we offer a comprehensive view of miRNA regulation in TNBC, treatment challenges presented by TNBC in the context of the tumor microenvironment and stem cell subpopulations, and current and emerging miRNA-based therapeutic strategies targeting various components of the TNBC microenvironment. In addition, we offer insight into novel targets that have potential for treating TNBC through multiple mechanisms in the tumor microenvironment simultaneously and those that may be synergistic with standard chemotherapies.

PharmaNet: Pharmaceutical discovery with deep recurrent neural networks

Preprint

Full-text available

Oct 2020

The discovery and development of novel pharmaceuticals is an area of active research mainly due to the large investments required and long payback times. As of 2016, the development of a novel drug candidate required up to $ USD 2.6 billion in investment for only 10% rate of approval by the FDA. To help decreasing the costs associated with the process, a number of in silico approaches have been developed with relatively low success due to limited predicting performance. Here, we introduced a machine learning-based algorithm as an alternative for a more accurate search of new pharmacological candidates, which takes advantage of Recurrent Neural Networks (RNN) for active molecule prediction within large databases. Our approach, termed PharmaNet was implemented here to search for ligands against specific cell receptors within 102 targets of the DUD-E database, which contains 22886 active molecules. PharmaNet comprises three main phases. First, a SMILES representation of the molecule is converted into a raw molecular image. Second, a convolutional encoder processes the data to obtain a fingerprint molecular image that is finally analyzed by a Recurrent Neural Network (RNN). This approach enables precise predictions of the molecules' target on the basis of the feature extraction, the sequence analysis and the relevant information filtered out throughout the process. Molecule Target prediction is a highly unbalanced detection problem and therefore, we propose that an adequate evaluation metric of performance is the area under the Normalized Average Precision (NAP) curve. PharmaNet largely surpasses the previous state-of-the-art method with 95.8% in the Receiver Operating Characteristic curve (ROC-AUC) and 58.9% in the NAP curve. We obtained a perfect performance for human farnesyl pyrophosphate synthase (FPPS), which is a potential target for antimicrobial and anticancer treatments. We decided to test PharmaNet for activity prediction against FPPS by searching in the CHEMBL data set. We obtained [3] potential inhibitors that were further validated through both molecular docking and in silico toxicity prediction. Most importantly, one of this candidates, CHEMBL2007613, was predicted as a potential antiviral due to its involvement on the PCDH17 pathway, which has been reported to be related to viral infections.

Connecting the Missing Dots: ncRNAs as Critical Regulators of Therapeutic Susceptibility in Breast Cancer

Article

Full-text available

Sep 2020

Simple Summary Despite considerable improvements in diagnosis and treatment, drug resistance remains the main cause of death in BC. Multiple lines of evidence demonstrated that ncRNAs play a vital role in BC resistance. Here, we summarized the molecular mechanisms by which miRNAs and lncRNAs may impact the therapeutic response in BC, highlighting that these molecules can be further exploited as predictive biomarkers and therapeutic targets. By merging data from various studies, we concluded that several ncRNAs, such as miR-221, miR-222, miR-451, UCA1, and GAS5 are strong candidates for pharmacological interventions since they are involved in resistance to all forms of therapies in BC. Therefore, we believe that our review provides an important reservoir of molecules that may translate into clinically useful biomarkers, laying the ground for the adoption of ncRNAs within mainstream routine oncology clinical practice. Abstract Whether acquired or de novo, drug resistance remains a significant hurdle in achieving therapeutic success in breast cancer (BC). Thus, there is an urge to find reliable biomarkers that will help in predicting the therapeutic response. Stable and easily accessible molecules such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are regarded as valuable prognostic biomarkers and therapeutic targets since they act as crucial regulators of the various mechanisms involved in BC drug resistance. Here, we reviewed the current literature on ncRNAs as mediators of resistance to systemic therapies in BC. Interestingly, upon integrating data results from individual studies, we concluded that miR-221, miR-222, miR-451, Urothelial Carcinoma Associated 1 (UCA1), and Growth arrest-specific 5 (GAS5) are strong candidates as prognostic biomarkers and therapeutic targets since they are regulating multiple drug resistance phenotypes in BC. However, further research around their clinical implications is needed to validate and integrate them into therapeutic applications. Therefore, we believe that our review may provide relevant evidence for the selection of novel therapeutic targets and prognostic biomarkers for BC and will serve as a foundation for future translational research in the field.

miRNA signatures underlie chemoresistance in the gemcitabine-resistant pancreatic ductal adenocarcinoma cell line MIA PaCa-2 GR

Article

Full-text available

Jun 2024

Introduction: Chemotherapy resistance remains a significant challenge in the treatment of pancreatic adenocarcinoma (PDAC), particularly in relation to gemcitabine (Gem), a commonly used chemotherapeutic agent. MicroRNAs (miRNAs) are known to influence cancer progression and chemoresistance. This study investigates the association between miRNA expression profiles and gemcitabine resistance in PDAC. Methods: The miRNA expression profiles of a gemcitabine-sensitive (GS) PDAC cell line, MIA PaCa-2, and its gemcitabine-resistant (GR) progeny, MIA PaCa-2 GR, were analyzed. miRNA sequencing (miRNA-seq) was employed to identify miRNAs expressed in these cell lines. Differential expression analysis was performed, and Ingenuity Pathway Analysis (IPA) was utilized to elucidate the biological functions of the differentially expressed miRNAs. Results: A total of 1867 miRNAs were detected across both cell lines. Among these, 97 (5.2%) miRNAs showed significant differential expression between the GR and GS cell lines, with 65 (3.5%) miRNAs upregulated and 32 (1.7%) miRNAs downregulated in the GR line. The most notably altered miRNAs were implicated in key biological processes such as cell proliferation, migration, invasion, chemosensitization, alternative splicing, apoptosis, and angiogenesis. A subset of these miRNAs was further analyzed in patient samples to identify potential markers for recurrent tumors. Discussion: The differential miRNA expression profiles identified in this study highlight the complex regulatory roles of miRNAs in gemcitabine resistance in PDAC. These findings suggest potential targets for improving prognosis and tailoring treatment strategies in PDAC patients, particularly those showing resistance to gemcitabine. Future research should focus on validating these miRNAs as biomarkers for resistance and exploring their therapeutic potential in overcoming chemoresistance.

A SYSTEMIC REVIEW OF MicroRNAs AS THERAPEUTIC TARGETS IN BREAST CANCER AND THEIR POTENTIAL APPLICATION IN CANCER THERAPY

Article

Full-text available

Jan 2024

Breast cancer, a multifaceted and heterogeneous disease, continues to pose challenges in both oncology research and clinical practice. This review delves into the intricate roles of microRNAs (miRNAs) in breast cancer, focusing on three pivotal dimensions: regulatory mechanisms, drug resistance, and diagnostic potential.As a regulator, miRNAs emerge as key players orchestrating breast cancer progression. Specifically, miR-205, the miR-200 family, and let-7 family play crucial roles in suppressing oncogenic processes, providing essential insights for comprehending and potentially mitigating breast cancer advancement.Drug resistance being a formidable challenge, a comprehensive exploration of how miRNAs contribute to chemotherapy ineffectiveness is required, particularly against widely used breast cancer drugs like tamoxifen, paclitaxel, and doxorubicin. The intricate interplay between miRNAs and drug resistance-associated genes underscores the urgency to explore innovative treatment modalities.From a diagnostic perspective, miRNAs exhibit remarkable promise as biomarkers for early-stage detection and prognostic assessment. Their expression patterns, linked with specific breast cancer subtypes, not only offer insights into disease outcomes but also provide valuable information about patient responses to treatment. Notably, miRNAs are detectable in bodily fluids such as serum, saliva, and urine, emphasizing their potential for non-invasive diagnostic applications.In summary, this review comprehensively underscores the profound impact of miRNAs in breast cancer, elucidating their intricate regulatory roles, addressing challenges related to drug resistance, and highlighting their promise as diagnostic tools. By unravelling the complexities of miRNA involvement in breast cancer, this work sets the stage for new horizons in therapeutic intervention and early disease management.

Docosahexaenoic Acid (DHA) Impairs Docetaxel-Induced Up-regulation of miR-30a-5p and miR-126-5p Tumor Suppressors in Gastric Cancer Cell Line

Article

Full-text available

Mar 2024

Objective: Owing to the synergistic effects of omega-3 fatty acids with chemotherapeutic agents in boosting response rates in gastric cancer (GC) patients, they became a promising addition to cancer therapy. Due to microRNAs (miRNAs) involvement in various cellular functions, their alterations in response to therapeutic interventions can offer insight into the efficacy of treatments. Our objective was to investigate docosahexaenoic acid (DHA) effects in conjunction with docetaxel on miR-30a-5p and miR-126-5p expressions in the MKN-45 cell line. Materials and Methods: The CancerMIRNome database was used to investigate miR-30a-5p and miR-126-5p expression changes, as well as their relation to diagnosis and survival in GC patients. Then, MKN-45 cells were treated with docetaxel, DHA, and their combination. Later, RT-qPCR was performed to measure miR-30a-5p and miR-126-5p expression levels. Results: It was discovered that miR-30a-5p and miR-126-5p expression were both decreased in GC patients and associated with GC diagnosis and survival, respectively. Following treatment with docetaxel and docetaxel-DHA, miR-30a-5p and miR-126-5p expression levels increased. Of course, the increase in miRNAs' expression observed in the combination form was not as strong as docetaxel alone. DHA alone decreased miR-30a-5p and miR-126-5p expressions. Conclusion: miR-30a-5p and miR-126-5p have important roles in GC tumorigenesis, and response to docetaxel and DHA. Attenuating effects of DHA on miR-30a-5p and miR-126-5p expression levels appear to counteract the beneficial effects of docetaxel on these miRNAs. Therefore, even though there is evidence of the anti-cancer effects of DHA in GC, not all DHA effects are anti-cancer.

Effect of miR-34a on the expression of clock and clock-controlled genes in DLD1 and Lovo human cancer cells with different backgrounds with respect to p53 functionality and 17β-estradiol-mediated regulation

Article

Full-text available

Oct 2023
PLOS ONE

The small non-coding RNA miR-34a is a p53-regulated miRNA that acts as a tumour suppressor of colorectal cancer (CRC). Oncogenesis is also negatively influenced by deregulation of the circadian system in many types of tumours with various genetic backgrounds. As the clock gene per2 was recently recognized as one of the target genes of miR-34a, we focused on the miR-34a-mediated influence on the circadian oscillator in CRC cell lines DLD1 and LoVo, which differ in their p53 status. Previously, a sex-dependent association between the expression of per2 and that of miR-34a was demonstrated in CRC patients. Therefore, we also investigated the effect of 17β-estradiol (E2) on miR-34a oncostatic functions. miR-34a mimic caused a pronounced inhibition of per2 expression in both cell lines. Moreover, miR-34a mimic significantly inhibited bmal1 expression in LoVo and rev-erbα expression in DLD1 cells and induced clock gene expression in both cell lines. miR-34a mimic caused a pronounced decrease in sirt1 and cyclin D1 expression, which may be related to the inhibition of proliferation observed after mir-34a administration in DLD1 cells. E2 administration inhibited the migration and proliferation of DLD1 cells. E2 and miR-34a, when administered simultaneously, did not potentiate each other’s effects. To conclude, miR-34a strongly influences the expression of components of the circadian oscillator without respect to p53 status and exerts its oncostatic effects via inhibition of sirt1 and cyclin D1 mRNA expression. E2 administration inhibits the growth of DLD1 cells; however, this effect seems to be independent of miR-34a-mediated action. With respect to the possible use of miR-34a in cancer treatment, clock genes can be considered as off-target genes, as changes in their expression induced by miR-34a treatment do not contribute to the oncostatic functions of miR-34a. Possible ambiguous oncogenic characteristics should be taken into consideration in future clinical studies focused on miR-34a.

From resistance to resilience: Uncovering chemotherapeutic resistance mechanisms; insights from established models

Article

Oct 2023
BBA-REV CANCER

Prognostic and immune implications of a novel 7-methylguanosine-related microRNA signature in breast invasive carcinoma: from exploration to validation

Article

Full-text available

May 2023
J CANCER RES CLIN

Objectives This study aims to develop and validate a prognostic signature based on 7-methylguanosine-related (M7G-related) miRNAs for predicting prognosis and immune implications in breast invasive carcinoma (BRCA). Materials and methods M7G-related miRNA data of BRCA were obtained from The Cancer Genome Atlas (TCGA). Least absolute shrinkage and selection operator (LASSO)-penalized, univariate, and multivariate Cox regression analyses were used to construct the prognostic signature. Furthermore, the predictive validity was verified using Kaplan–Meier (KM) survival risk and receiver operating characteristic (ROC) plots. Internal random sampling verification was used to simplify and validate the signature. RT-qPCR was used to quantify the expression level of transcriptional profiles. The independent prognostic role of the risk score was validated using univariate and multivariate regression. Single-sample Gene Set Enrichment Analysis (ssGSEA) was used for functional and immune enrichment analysis. Results A total of 18 M7G-related miRNAs were identified to construct the prognostic signature in BRCA. The low-risk group exhibited significantly higher overall survival than the high-risk group in the KM survival plot (P < 0.001). The area under the curve (AUC) for 1-, 3-, and 5-year survivals in the ROC curve were 0.737, 0.724, and 0.702, respectively. The survival significance in the training and testing cohorts was confirmed by random sampling verification. The most prominent miRNAs in the signature were the miR-7, miR-139, miR-10b, and miR-4728. Furthermore, immune scores for B, mast, and Th1 cells varied between risk groups. Our research demonstrated that CD52 was the most positively correlated gene with immune cells and functions in BRCA. Conclusion Our study presents a comprehensive and systematic analysis of M7G-related miRNAs to construct a prognostic signature in BRCA. The signature demonstrated excellent prognostic validity, with the risk score as an independent prognostic factor. These results provide critical evidence for further investigation of M7G miRNAs and offer new insights for BRCA patients in the context of effective immunotherapy.

A miR-34a-guided, tRNA i Met -derived, piR_019752-like fragment (tRiMetF31) suppresses migration and angiogenesis of breast cancer cells via targeting PFKFB3

Article

Full-text available

Aug 2022

Although we recently demonstrated that miR-34a directly targets tRNAiMet precursors via Argonaute 2 (AGO2)-mediated cleavage, consequently attenuating the proliferation of breast cancer cells, whether tRNAiMet fragments derived from this cleavage influence breast tumor angiogenesis remains unknown. Here, using small-RNA-Seq, we identified a tRNAiMet-derived, piR_019752-like 31-nt fragment tRiMetF31 in breast cancer cells expressing miR-34a. Bioinformatic analysis predicted 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) as a potential target of tRiMrtF31, which was validated by luciferase assay. tRiMetF31 was downregulated, whereas PFKFB3 was overexpressed in cancer cell lines. Overexpression of tRiMetF31 profoundly inhibited the migration and angiogenesis of two breast cancer cell lines while slightly inducing apoptosis. Conversely, knockdown of tRiMetF31 restored PFKFB3-driven angiogenesis. miR-34a was downregulated, whereas tRNAiMet and PFKFB3 were upregulated in breast cancer, and elevated PFKFB3 significantly correlated with metastasis. Our findings demonstrate that tRiMetF31 profoundly suppresses angiogenesis by silencing PFKFB3, presenting a novel target for therapeutic intervention in breast cancer.

A miR-34a-guided, tRNAiMet-derived, piR_019752-like fragment (tRiMetF31) suppresses migration and angiogenesis of breast cancer cells via targeting PFKFB3

Article

Full-text available

Aug 2022

Although we recently demonstrated that miR-34a directly targets tRNA i Met precursors via Argonaute 2 (AGO2)-mediated cleavage, consequently attenuating the proliferation of breast cancer cells, whether tRNA i Met fragments derived from this cleavage influence breast tumor angiogenesis remains unknown. Here, using small-RNA-Seq, we identified a tRNA i Met -derived, piR_019752-like 31-nt fragment tRiMetF31 in breast cancer cells expressing miR-34a. Bioinformatic analysis predicted 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) as a potential target of tRiMrtF31, which was validated by luciferase assay. tRiMetF31 was downregulated, whereas PFKFB3 was overexpressed in cancer cell lines. Overexpression of tRiMetF31 profoundly inhibited the migration and angiogenesis of two breast cancer cell lines while slightly inducing apoptosis. Conversely, knockdown of tRiMetF31 restored PFKFB3-driven angiogenesis. miR-34a was downregulated, whereas tRNA i Met and PFKFB3 were upregulated in breast cancer, and elevated PFKFB3 significantly correlated with metastasis. Our findings demonstrate that tRiMetF31 profoundly suppresses angiogenesis by silencing PFKFB3, presenting a novel target for therapeutic intervention in breast cancer.

Down Regulated Expression Levels of miR-27b and miR-451a as a Potential Biomarker for Triple Negative Breast Cancer Patients Undergoing TAC Chemotherapy

Article

Full-text available

Mar 2022

Background: Triple negative breast cancer (TNBC) is associated with poor prognosis, aggressive phenotype(s) of tumours, partial chemotherapy response, and lack of clinically proven therapies. MicroRNAs (miRNAs) can target and modulate key genes that are involved in TNBC chemotherapy. Deregulated miRNA expression is highly involved in anti-cancer drug resistance phenotype and thus, miRNAs tend to be promising candidates for prediction of chemotherapy response and recurrence. Aim: This study aimed to investigate the expression levels of selected miRNAs (miR-21, miR-27b, miR-34a, miR-182, miR-200c and miR-451a) in cancerous and normal adjacent tissues of TNBC patients and to correlate with the clinicopathological data. Methods: Forty-one (41) FFPE tissue block of histopathologically confirmed TNBC patients was collected. Total RNA from the cancerous and adjacent non-cancerous tissues were isolated, transcribed, and pre-amplified. The relative expression level of miRNAs in tumour and normal adjacent tissues of TNBC patients was analysed using qRT-PCR. Results: Out of six miRNAs studied, the relative expression of miR-27b and miR-451a were found to be significantly lower in cancerous as compared to normal adjacent tissues of TNBC patients. In addition, a significant down regulation of miR-451a was also observed in infiltrating ductal carcinoma subtype, stages I and II, in both grade II and III, premenopausal and postmenopausal as well as in those with positive axillary lymph node metastases. Conclusion: The results suggest the possible utilization of miR-27b and miR-451a expression levels as potential predictive risk markers for TNBC patients undergoing TAC chemotherapy.

The Roles of microRNAs in Cancer Multidrug Resistance

Article

Full-text available

Feb 2022

Simple Summary The resistance of neoplastic cells to multiple drugs is a serious problem in cancer chemotherapy. The molecular causes of multidrug resistance in cancer are largely known, but less is known about the mechanisms by which cells deliver phenotypic changes that resist the attack of anticancer drugs. The findings of RNA interference based on microRNAs represented a breakthrough in biology and pointed to the possibility of sensitive and targeted regulation of gene expression at the post-transcriptional level. Such regulation is also involved in the development of multidrug resistance in cancer. The aim of the current paper is to summarize the available knowledge on the role of microRNAs in resistance to multiple cancer drugs. Abstract Cancer chemotherapy may induce a multidrug resistance (MDR) phenotype. The development of MDR is based on various molecular causes, of which the following are very common: induction of ABC transporter expression; induction/activation of drug-metabolizing enzymes; alteration of the expression/function of apoptosis-related proteins; changes in cell cycle checkpoints; elevated DNA repair mechanisms. Although these mechanisms of MDR are well described, information on their molecular interaction in overall multidrug resistance is still lacking. MicroRNA (miRNA) expression and subsequent RNA interference are candidates that could be important players in the interplay of MDR mechanisms. The regulation of post-transcriptional processes in the proteosynthetic pathway is considered to be a major function of miRNAs. Due to their complementarity, they are able to bind to target mRNAs, which prevents the mRNAs from interacting effectively with the ribosome, and subsequent degradation of the mRNAs can occur. The aim of this paper is to provide an overview of the possible role of miRNAs in the molecular mechanisms that lead to MDR. The possibility of considering miRNAs as either specific effectors or interesting targets for cancer therapy is also analyzed.

The effects of estrogen on targeted cancer therapy drugs

Article

Feb 2022
PHARMACOL RES

Improving the efficacy of anticancer drugs is especially challenging. Estrogen is a sex hormone that not only promotes the development of female secondary sexual characteristics, but also supports many important physiological functions. Interestingly, estrogen has shown to be vital for the activity of some anticancer drugs, such as adriamycin, cisplatin, olaparib, trastuzumab, bevacizumab, tamoxifen, cyclophosphamide, methotrexate, and paclitaxel. Although there are many reasons for the differences in therapeutic effects among cancer patients, estrogen status is undoubtedly a very important factor. In view of the importance of the crosstalk between estrogen signaling and drug therapy for cancer, this review summarizes the effects of estrogen on the targets, metabolism and resistance of anticancer drugs and describes the related pathways and underlying mechanisms. Here, an analysis of the close relationship between estrogen and cancer drug therapy was conducted to clarify the effects of estrogen on the therapeutic efficacy of anticancer drugs to facilitate the future development of specific drug treatment strategies to achieve optimal outcomes.

MicroRNA and Alternative mRNA Splicing Events in Cancer Drug Response/Resistance: Potent Therapeutic Targets

Article

Full-text available

Dec 2021

Cancer is a multifaceted disease that involves several molecular mechanisms including changes in gene expression. Two important processes altered in cancer that lead to changes in gene expression include altered microRNA (miRNA) expression and aberrant splicing events. MiRNAs are short non-coding RNAs that play a central role in regulating RNA silencing and gene expression. Alternative splicing increases the diversity of the proteome by producing several different spliced mRNAs from a single gene for translation. MiRNA expression and alternative splicing events are rigorously regulated processes. Dysregulation of miRNA and splicing events promote carcinogenesis and drug resistance in cancers including breast, cervical, prostate, colorectal, ovarian and leukemia. Alternative splicing may change the target mRNA 3′UTR binding site. This alteration can affect the produced protein and may ultimately affect the drug affinity of target proteins, eventually leading to drug resistance. Drug resistance can be caused by intrinsic and extrinsic factors. The interplay between miRNA and alternative splicing is largely due to splicing resulting in altered 3′UTR targeted binding of miRNAs. This can result in the altered targeting of these isoforms and altered drug targets and drug resistance. Furthermore, the increasing prevalence of cancer drug resistance poses a substantial challenge in the management of the disease. Henceforth, molecular alterations have become highly attractive drug targets to reverse the aberrant effects of miRNAs and splicing events that promote malignancy and drug resistance. While the miRNA–mRNA splicing interplay in cancer drug resistance remains largely to be elucidated, this review focuses on miRNA and alternative mRNA splicing (AS) events in breast, cervical, prostate, colorectal and ovarian cancer, as well as leukemia, and the role these events play in drug resistance. MiRNA induced cancer drug resistance; alternative mRNA splicing (AS) in cancer drug resistance; the interplay between AS and miRNA in chemoresistance will be discussed. Despite this great potential, the interplay between aberrant splicing events and miRNA is understudied but holds great potential in deciphering miRNA-mediated drug resistance.

New Insight into the Effects of Metformin on Diabetic Retinopathy, Aging and Cancer: Nonapoptotic Cell Death, Immunosuppression, and Effects beyond the AMPK Pathway

Article

Full-text available

Aug 2021
INT J MOL SCI

Under metabolic stress conditions such as hypoxia and glucose deprivation, an increase in the AMP:ATP ratio activates the AMP-activated protein kinase (AMPK) pathway, resulting in the modulation of cellular metabolism. Metformin, which is widely prescribed for type 2 diabetes mellitus (T2DM) patients, regulates blood sugar by inhibiting hepatic gluconeogenesis and promoting insulin sensitivity to facilitate glucose uptake by cells. At the molecular level, the most well-known mechanism of metformin-mediated cytoprotection is AMPK pathway activation, which modulates metabolism and protects cells from degradation or pathogenic changes, such as those related to aging and diabetic retinopathy (DR). Recently, it has been revealed that metformin acts via AMPK- and non-AMPK-mediated pathways to exert effects beyond those related to diabetes treatment that might prevent aging and ameliorate DR. This review focuses on new insights into the anticancer effects of metformin and its potential modulation of several novel types of nonapoptotic cell death, including ferroptosis, pyroptosis, and necroptosis. In addition, the antimetastatic and immunosuppressive effects of metformin and its hypothesized mechanism are also discussed, highlighting promising cancer prevention strategies for the future.

A Comprehensive RNA Study to Identify circRNA and miRNA Biomarkers for Docetaxel Resistance in Breast Cancer

Article

Full-text available

May 2021

To investigate the relationship between non-coding RNAs [especially circular RNAs (circRNAs)] and docetaxel resistance in breast cancer, and to find potential predictive biomarkers for taxane-containing therapies, we have performed transcriptome and microRNA (miRNA) sequencing for two established docetaxel-resistant breast cancer (DRBC) cell lines and their docetaxel-sensitive parental cell lines. Our analyses revealed differences between circRNA signatures in the docetaxel-resistant and -sensitive breast cancer cells, and discovered circRNAs generated by multidrug-resistance genes in taxane-resistant cancer cells. In DRBC cells, circABCB1 was identified and validated as a circRNA that is strongly up-regulated, whereas circEPHA3.1 and circEPHA3.2 are strongly down-regulated. Furthermore, we investigated the potential functions of these circRNAs by bioinformatics analysis, and miRNA analysis was performed to uncover potential interactions between circRNAs and miRNAs. Our data showed that circABCB1, circEPHA3.1 and circEPHA3.2 may sponge up eight significantly differentially expressed miRNAs that are associated with chemotherapy and contribute to docetaxel resistance via the PI3K-Akt and AGE-RAGE signaling pathways. We also integrated differential expression data of mRNA, long non-coding RNA, circRNA, and miRNA to gain a global profile of multi-level RNA changes in DRBC cells, and compared them with changes in DNA copy numbers in the same cell lines. We found that Chromosome 7 q21.12-q21.2 was a common region dominated by multi-level RNA overexpression and DNA amplification, indicating that overexpression of the RNA molecules transcribed from this region may result from DNA amplification during stepwise exposure to docetaxel. These findings may help to further our understanding of the mechanisms underlying docetaxel resistance in breast cancer.

PharmaNet: Pharmaceutical discovery with deep recurrent neural networks

Article

Full-text available

Apr 2021
PLOS ONE

The discovery and development of novel pharmaceuticals is an area of active research mainly due to the large investments required and long payback times. As of 2016, the development of a novel drug candidate required up to $ USD 2.6 billion in investment for only 10% rate of approval by the FDA. To help decreasing the costs associated with the process, a number of in silico approaches have been developed with relatively low success due to limited predicting performance. Here, we introduced a machine learning-based algorithm as an alternative for a more accurate search of new pharmacological candidates, which takes advantage of Recurrent Neural Networks (RNN) for active molecule prediction within large databases. Our approach, termed PharmaNet was implemented here to search for ligands against specific cell receptors within 102 targets of the DUD-E database, which contains 22886 active molecules. PharmaNet comprises three main phases. First, a SMILES representation of the molecule is converted into a raw molecular image. Second, a convolutional encoder processes the data to obtain a fingerprint molecular image that is finally analyzed by a Recurrent Neural Network (RNN). This approach enables precise predictions of the molecules' target on the basis of the feature extraction, the sequence analysis and the relevant information filtered out throughout the process. Molecule Target prediction is a highly unbalanced detection problem and therefore, we propose that an adequate evaluation metric of performance is the area under the Normalized Average Precision (NAP) curve. PharmaNet largely surpasses the previous state-of-the-art method with 97.7% in the Receiver Operating Characteristic curve (ROC-AUC) and 65.5% in the NAP curve. We obtained a perfect performance for human farnesyl pyrophosphate synthase (FPPS), which is a potential target for antimicrobial and anticancer treatments. We decided to test PharmaNet for activity prediction against FPPS by searching in the CHEMBL data set. We obtained three (3) potential inhibitors that were further validated through both molecular docking and in silico toxicity prediction. Most importantly, one of this candidates, CHEMBL2007613, was predicted as a potential antiviral due to its involvement on the PCDH17 pathway, which has been reported to be related to viral infections.

Exosomal microRNAs: Pleiotropic Impacts on Breast Cancer Metastasis and Their Clinical Perspectives

Article

Full-text available

Apr 2021

As a major threat factor for female health, breast cancer (BC) has garnered a lot of attention for its malignancy and diverse molecules participating in its carcinogenesis process. Among these complex carcinogenesis processes, cell proliferation, epithelial-to-mesenchymal transition (EMT), mesenchymal-to-epithelial transition (MET), and angiogenesis are the major causes for the occurrence of metastasis and chemoresistance which account for cancer malignancy. MicroRNAs packaged and secreted in exosomes are termed “exosomal microRNAs (miRNAs)”. Nowadays, more researches have uncovered the roles of exosomal miRNAs played in BC metastasis. In this review, we recapitulated the dual actions of exosomal miRNAs exerted in the aggressiveness of BC by influencing migration, invasion, and distant metastasis. Next, we presented how exosomal miRNAs modify angiogenesis and stemness maintenance. Clinically, several exosomal miRNAs can govern the transformation between drug sensitivity and chemoresistance. Since the balance of the number and type of exosomal miRNAs is disturbed in pathological conditions, they are able to serve as instructive biomarkers for BC diagnosis and prognosis. More efforts are needed to connect the theoretical studies and clinical traits together. This review provides an outline of the pleiotropic impacts of exosomal miRNAs on BC metastasis and their clinical implications, paving the way for future personalized drugs.

Therapeutic applications of CRISPR/Cas9 in breast cancer and delivery potential of gold nanomaterials

Article

Full-text available

Dec 2020

Globally, approximately 1 in 4 cancers in women are diagnosed as breast cancer (BC). Despite significant advances in the diagnosis and therapy BCs, many patients develop metastases or relapses. Hence, novel therapeutic strategies are required, that can selectively and efficiently kill malignant cells. Direct targeting of the genetic and epigenetic aberrations that occur in BC development is a promising strategy to overcome the limitations of current therapies, which target the tumour phenotype. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system, composed of only an easily modifiable single guide RNA (sgRNA) sequence bound to a Cas9 nuclease, has revolutionised genome editing due to its simplicity and efficiency compared to earlier systems. CRISPR/Cas9 and its associated catalytically inactivated dCas9 variants facilitate the knockout of overexpressed genes, correction of mutations in inactivated genes, and reprogramming of the epigenetic landscape to impair BC growth. To achieve efficient genome editing in vivo, a vector is required to deliver the components to target cells. Gold nanomaterials, including gold nanoparticles and nanoclusters, display many advantageous characteristics that have facilitated their widespread use in theranostics, as delivery vehicles, and imaging and photothermal agents. This review highlights the therapeutic applications of CRISPR/Cas9 in treating BCs, and briefly describes gold nanomaterials and their potential in CRISPR/Cas9 delivery.

LncRNA SNHG7 Mediates the Chemoresistance and Stemness of Breast Cancer by Sponging miR-34a

Article

Full-text available

Nov 2020

Chemoresistance is considered to be a major cause of the recurrence and metastasis of breast cancer (BC). LncRNA SNHG7 has been reported to be upregulated in breast cancer and to promote tumor progression and metastasis. Nevertheless, the function and potential regulatory mechanism of SNHG7 in BC drug resistance are still largely unclear. This study indicated that SNHG7 was highly expressed in chemoresistant BC tissues and cells. Upregulated SNHG7 might predict a low pCR rate and poor clinical outcome in BC patients. Knockdown of SNHG7 enhanced drug sensitivity and drug-induced apoptosis in chemoresistant BC cells. In terms of the mechanism, miR-34a was found to be a target of SNHG7 and its expression in breast cancer tissues and chemoresistant cell lines was negatively correlated with SNHG7 expression. Importantly, sh-SNHG7 upregulated miR-34a expression, reduced the percentages of CD44⁺/CD24⁻cells, and inhibited sphere-formation and stem cell factor (Oct4, Nanog, SOX2) expression. Functional loss experiments showed that the repressive effect of SNHG7 knockdown on BC cell stemness was partially reversed by transfection with miR-34a inhibitors. In summary, this study indicated that SNHG7 contributed to the chemoresistance of BC and mediated chemoresistance and cancer stemness by sponging miR-34a.

The Extracellular Matrix and Vesicles Modulate the Breast Tumor Microenvironment

Article

Full-text available

Oct 2020

Emerging evidence has shown multiple roles of the tumor microenvironment (TME) components, specifically the extracellular matrix (ECM), in breast cancer development, progression, and metastasis. Aside from the biophysical properties and biochemical composition of the breast ECM, the signaling molecules are extremely important in maintaining homeostasis, and in the breast TME, they serve as the key components that facilitate tumor progression and immune evasion. Extracellular vesicles (EVs), the mediators that convey messages between the cells and their microenvironment through signaling molecules, have just started to capture attention in breast cancer research. In this comprehensive review, we first provide an overview of the impact of ECM in breast cancer progression as well as the alterations occurring in the TME during this process. The critical importance of EVs and their biomolecular contents in breast cancer progression and metastasis are also discussed. Finally, we discuss the potential biomedical or clinical applications of these extracellular components, as well as how they impact treatment outcomes.

Inhibition of Chk1 by miR-320c increases oxaliplatin responsiveness in triple-negative breast cancer

Article

Full-text available

Oct 2020

Checkpoint kinase 1 (Chk1) expression is enhanced in most cancers owing to oncogenic activation and constant replicative stress. Chk1 inactivation is a promising cancer therapy, as its inactivation leads to genomic instability, chromosomal catastrophe, and cancer cell death. Herein, we observed that miR-320c, downregulated in triple-negative breast cancer (TNBC) patients, can target Chk1. In addition, downregulated miR-320c expression was associated with poor overall survival in TNBC patients. As Chk1 was associated with the DNA damage response (DDR), we investigated the effect of miR-320c on DDR in TNBC cells. To induce DNA damage, we used platinum-based drugs, especially oxaliplatin, which is most effective with miR-320c. We observed that overexpression of miR-320c in TNBC regulated the oxaliplatin responsiveness by mediating DNA damage repair through the negative regulation of Chk1 in vitro. Furthermore, using a xenograft model, a combination of miR-320c mimic and oxaliplatin effectively inhibited tumor progression. These investigations indicate the potential of miR-320c as a marker of oxaliplatin responsiveness and a therapeutic target to increase the efficacy of chemotherapy in TNBC.

Involvement and Clinical Aspects of MicroRNA in Osteosarcoma

Article

Full-text available

Jun 2016
INT J MOL SCI

Osteosarcoma (OS) is the most common primary bone cancer in children and adolescents, but its pathogenesis has been difficult to establish because of its well-known heterogeneous nature. OS has been associated with genetic and cytogenetic abnormalities, which include function-impairing mutations in tumor suppressors and the activation of oncogenes. OS tumorigenesis has been linked to alterations of several genes characterized by a high level of genetic instability and recurrent DNA amplifications and deletions. MicroRNAs (miRNAs), 18-25-nucleotide noncoding RNAs, are critical for various biological processes like differentiation, cell growth and cell death. Dysregulation of miRNA expression leads to phenotypic and genotypic changes in cells, which leads to cancer. Studies on miRNAs have initiated a significant effect in both diagnosis and treatment of cancer. This review focuses on the current knowledge of clinical applications of miRNAs for the better diagnosis and management of OS.

Role of microRNA in forming breast carcinoma

Article

Aug 2020

MicroRNA (miRNA) is a regulatory molecule which supervises various processes and gene expression. RNA polymerase II enzyme regulates miRNA gene transcription whereas miRNA biogenesis includes various proteins or enzymes. Starting from cell proliferation, cell cycle regulation and apoptosis are regulated by alteration in cancerous cells. Aberrant cell proliferation takes place and apoptosis is usually inhibited by oncogenic miRNA. The miRNA can be oncogenic or tumor suppressor in nature and their functions are opposite to each other. During tumorigenesis, the upregulation of oncogenic miRNA is mainly observed along with downregulation of tumor suppressors. The miRNA can degrade the target mRNA by using a slicer named argonaute protein (Ago) or by inhibiting the translation process. The miRNA may positively or negatively regulate the formation of tumor in breast by interfering with cellular activities. Thus, miRNA can be significantly used as a biomarker for monitoring breast cancer. In therapeutic intervention, the delivery of tumor suppressor miRNAs in a cancer patient can help in recovering from cancer. Different miRNAs regulate positively or negatively in these therapies. This review is mainly focused on the role of miRNA in breast carcinoma, its mechanisms and different therapies. It also includes miRNA biogenesis and different miRNAs involved in breast cancer.

The Role of Necroptosis in ROS-Mediated Cancer Therapies and Its Promising Applications

Article

Full-text available

Aug 2020

Over the past decades, promising therapies targeting different signaling pathways have emerged. Among these pathways, apoptosis has been well investigated and targeted to design diverse chemotherapies. However, some patients are chemoresistant to these therapies due to compromised apoptotic cell death. Hence, exploring alternative treatments aimed at different mechanisms of cell death seems to be a potential strategy for bypassing impaired apoptotic cell death. Emerging evidence has shown that necroptosis, a caspase-independent form of cell death with features between apoptosis and necrosis, can overcome the predicament of drug resistance. Furthermore, previous studies have also indicated that there is a close correlation between necroptosis and reactive oxygen species (ROS); both necroptosis and ROS play significant roles both under human physiological conditions such as the regulation of inflammation and in cancer biology. Several small molecules used in experiments and clinical practice eliminate cancer cells via the modulation of ROS and necroptosis. The molecular mechanisms of these promising therapies are discussed in detail in this review.

Evaluation of miR-34a Effect on CCND1 mRNA Level and Sensitization of Breast Cancer Cell Lines to Paclitaxel

Article

Full-text available

Jun 2020

Background: A growing body of literature has revealed the effective role of miR-34a, as a tumor suppressor and regulator of expression of multiple targets in tumorigenesis and cancer progression. This study aimed at evaluating the potential effects of miR-34a alone or in combination with paclitaxel on breast cancer cells. Methods: After miR-34a transduction by lentiviral vectors in two MCF-7 and MDA-MB-231 cell lines of breast cancer, effects of the elevated expression of miR-34a in the cell viability and the cell proliferation were determined using MTT assay in treated and untreated cells with paclitaxel. The mRNA level of the CCND1 gene was then measured in the two cell lines using the qRT-PCR assay. Finally, the influence of miR-34a and paclitaxel on apoptosis and cell cycle progression were examined by flow cytometry. Results: The CCND1 mRNA expression levels were significantly down-regulated by overexpressed lentiviral miR-34a in MCF-7 and MDA-MB-231 cells. Combined treatment by miR-34a and paclitaxel reduced the cell viability and proliferation compared to single-drug treatment. In addition, the cell cycle arrest appeared at two phases by the combination of miR-34a and paclitaxel in MDA-MB-231 cells. Conclusion: Our results suggest that miR34a, in combination with paclitaxel, has a potential for decreasing the cell viability and proliferation. Moreover, it can reduce the expression of CCND1 mRNA independent of the paclitaxel effect.

The role of miR‐34 in cancer drug resistance

Article

Full-text available

Feb 2020

Resistance to conventional chemotherapy remains a major cause of cancer relapse and cancer‐related deaths. Therefore, there is an urgent need to overcome resistance barriers. To improve cancer treatment approaches, it is critical to elucidate the basic mechanisms underlying drug resistance. Increasingly, the mechanisms involving micro‐RNAs (miRNAs) are studied because miRNAs are also considered practical therapeutic options due to high degrees of specificity, efficacy, and accuracy, as well as their ability to target multiple genes at the same time. Years of research have firmly established miR‐34 as a key tumor suppressor miRNA whose target genes are involved in drug resistance mechanisms. Indeed, numerous articles show that low levels of circulating miR‐34 or tumor‐specific miR‐34 expression are associated with poor response to chemotherapy. In addition, elevation of inherently low miR‐34 levels in resistant cancer cells effectively restores sensitivity to chemotherapeutic agents. Here, we review this literature, also highlighting some contradictory observations. In addition, we discuss the potential utility of miR‐34 expression as a predictive biomarker for chemotherapeutic drug response. Although caution needs to be exercised, miR‐34 is emerging as a biomarker that could improve cancer precision medicine. This review article aims to provide an extensive overview and discuss the achievements of this study, highlighting the combination of therapies involving miR‐34a and diverse chemotherapeutics agents to treat several types of cancer.

Identification of chemoresistance associated key genes-miRNAs-TFs in docetaxel resistant breast cancer by bioinformatics analysis

Article

Full-text available

Apr 2024

The present study aimed to identify the differentially expressed genes (DEGs) and enriched pathways in docetaxel (DTX) resistant breast cancer cell lines by bioinformatics analysis. The microarray dataset GSE28784 was obtained from gene expression omnibus (GEO) database. The differentially expressed genes (DEGs), gene ontology (GO), and Kyoto Encyclopedia of gene and genome (KEGG) pathway analyses were performed with the help of GEO2R and DAVID tools. Furthermore, the protein–protein interaction (PPI) and hub-gene network of DEGs were constructed using STRING and Cytohubba tools. The prognostic values of hub genes were calculated with the help of the Kaplan–Meier plotter database. From the GEO2R analysis, 222 DEGs were identified of which 120 are upregulated and 102 are downregulated genes. In the PPIs network, five up-regulated genes including CCL2, SPARC, CYR61, F3, and MFGE8 were identified as hub genes. It was observed that low expression of six hub genes CXCL8, CYR61, F3, ICAM1, PLAT, and THBD were significantly correlated with poor overall survival of BC patients in survival analysis. miRNA analysis identified that hsa-mir-16-5p, hsa-mir-335-5p, hsa-mir-124-3p, hsa-mir-20a-5p, and hsa-mir-155-5p are the top 5 interactive miRNAs that are commonly interacting with more hub genes with degree score of greater than five. Additionally, drug-gene interaction analysis was performed to identify drugs which are could potentially elevate/lower the expression levels of hub genes. In summary, the gene-miRNAs-TFs network and subsequent correlation of candidate drugs with hub genes may improve individualized diagnosis and help select appropriate combination therapy for DTX-resistant BC in the future.

A novel nanoprobe for visually investigating the controversial role of miRNA-34a as oncogene or tumor suppressor in cancer cells

Article

Jan 2024

MiRNA-targeted therapy has become a hot topic in current cancer research. The key to this treatment strategy is to clarify the specific role of miRNA in cancer. However, the roles...

miRNA Expression Profiling in Human Breast Cancer Diagnostics and Therapy

Article

Full-text available

Nov 2023
CURR ISSUES MOL BIOL

Breast cancer is one of the most commonly diagnosed cancer types worldwide. Regarding molecular characteristics and classification, it is a heterogeneous disease, which makes it more challenging to diagnose. As is commonly known, early detection plays a pivotal role in decreasing mortality and providing a better prognosis for all patients. Different treatment strategies can be adjusted based on tumor progression and molecular characteristics, including personalized therapies. However, dealing with resistance to drugs and recurrence is a challenge. The therapeutic options are limited and can still lead to poor clinical outcomes. This review aims to shed light on the current perspective on the role of miRNAs in breast cancer diagnostics, characteristics, and prognosis. We discuss the potential role of selected non-coding RNAs most commonly associated with breast cancer. These include miR-21, miR-106a, miR-155, miR-141, let-7c, miR-335, miR-126, miR-199a, miR-101, and miR-9, which are perceived as potential biomarkers in breast cancer prognosis, diagnostics, and treatment response monitoring. As miRNAs differ in expression levels in different types of cancer, they may provide novel cancer therapy strategies. However, some limitations regarding dynamic alterations, tissue-specific profiles, and detection methods must also be raised.

Breast cancer: miRNAs monitoring chemoresistance and systemic therapy

Article

Full-text available

Jun 2023

With a high mortality rate that accounts for millions of cancer-related deaths each year, breast cancer is the second most common malignancy in women. Chemotherapy has significant potential in the prevention and spreading of breast cancer; however, drug resistance often hinders therapy in breast cancer patients. The identification and the use of novel molecular biomarkers, which can predict response to chemotherapy, might lead to tailoring breast cancer treatment. In this context, accumulating research has reported microRNAs (miRNAs) as potential biomarkers for early cancer detection, and are conducive to designing a more specific treatment plan by helping analyze drug resistance and sensitivity in breast cancer treatment. In this review, miRNAs are discussed in two alternative ways-as tumor suppressors to be used in miRNA replacement therapy to reduce oncogenesis and as oncomirs to lessen the translation of the target miRNA. Different miRNAs like miR-638, miR-17, miR-20b, miR-342, miR-484, miR-21, miR-24, miR-27, miR-23 and miR-200 are involved in the regulation of chemoresistance through diverse genetic targets. For instance, tumor-suppressing miRNAs like miR-342, miR-16, miR-214, and miR-128 and tumor-promoting miRNAs like miR101 and miR-106-25 cluster regulate the cell cycle, apoptosis, epithelial to mesenchymal transition and other pathways to impart breast cancer drug resistance. Hence, in this review, we have discussed the significance of miRNA biomarkers that could assist in providing novel therapeutic targets to overcome potential chemotherapy resistance to systemic therapy and further facilitate the design of tailored therapy for enhanced efficacy against breast cancer.

Exosomal miRNAs as novel avenues for breast cancer treatment

Article

Full-text available

Mar 2023

Breast cancer is the most commonly diagnosed cancer and a leading cause of death in women worldwide. It is a heterogeneous disease, as shown by the gene expression profiles of breast cancer samples. It begins in milk-producing ducts, with a high degree of diversity between and within tumors, as well as among cancer-bearing individuals. The enhanced prevalence of breast cancer is influenced by various hormonal, lifestyle, and environmental factors, and very early onset of the disease correlates strongly with the risk of local and distant recurrence. Many subtypes are difficult to treat with conventional therapeutic modalities, and therefore, optimal management and early diagnosis are the first steps to minimizing the mortality linked with breast cancer. The use of newer methods of nanotechnology extends beyond the concept of synthesizing drug delivery mechanisms into the creation of new therapeutics, such as delivering chemotherapeutics with nanomaterial properties. Exosomes, a class of nanovesicles, are emerging as novel tools for deciphering the patient-specific proteins and biomarkers across different disease models, including breast cancer. In this review, we address the role of exosomal miRNA in breast cancer diagnosis and treatment.

9782832513651

Book

Full-text available

Feb 2023

Breast cancer remains one of the most challenging diseases, with unexpected behavior even after several years of remission. Breast cancer molecular classification represented a big step in the elucidation of this malignant heterogeneity, but it seems that it is not enough to explain some hidden sides of the disease, especially the development of therapy resistance. The papers published in the Research Topic -Drug Resistance in Breast Cancer – Mechanisms and Approaches to Overcome Chemoresistance in Frontiers in Oncology (Figure 1) suggested that molecular classification needs to be improved by adding new criteria derived from more accurate experimental and clinical data. Also, this Research Topic highlighted the invasion ability and metastasis of breast cancer stem cells and their response and resistance to current therapies. This Research Topic contains a well balanced proportion of valuable clinical and experimental studies in the field of breast cancer, which are extremely useful for both clinicians and academic researchers.

Time above threshold plasma concentrations as pharmacokinetic parameter in the comparison of oral and intravenous docetaxel treatment of breast cancer tumors

Article

Nov 2022

Background: Prolonging the time which plasma concentrations of antimitotic drugs, such as the taxanes, exceed cytotoxic threshold levels may be beneficial for their efficacy. Orally administered docetaxel offers an undemanding approach to optimize such time above threshold plasma concentrations (tC>threshold). Methods: A nonsystematic literature screen was performed to identify studies reporting in-vitro half-maximal inhibitory concentration (IC50) values for docetaxel. Pharmacokinetics of intravenously (i.v.) docetaxel (75 mg/m2) and orally administered docetaxel (ModraDoc006) co-administered with ritonavir (r) given twice daily (30 + 20 mg concomitant with 100 mg ritonavir bis in die) were simulated using previously developed population models. TC>threshold was calculated for a range of relevant thresholds in terms of in-vitro cytotoxicity and plasma concentrations achieved after i.v. and oral administration of docetaxel. A published tumor growth inhibition model for i.v. docetaxel was adapted to predict the effect of attainment of time above threshold levels on tumor dynamics. Results: Identified studies reported a wide range of in vitro IC50 values [median 0.04 µmol/L, interquartile range (IQR): 0.0046-0.62]. At cytotoxic thresholds <0.078 µmol/L oral docetaxel shows up to ~7.5-fold longer tC>threshold within each 3-week cycle for a median patient compared to i.v.. Simulations of tumor dynamics showed the increased relative potential of oral docetaxel for inhibition of tumor growth at thresholds of 0.075, 0.05 and 0.005 µmol/L. Conclusion: ModraDoc006/r is superior to i.v. docetaxel 75 mg/m2 in terms of median time above cytotoxic threshold levels <0.078 µmol/L. This may indicate superior cytotoxicity and inhibition of tumor growth compared to i.v. administration for relatively docetaxel-sensitive tumors.

DNA Damage Response in Cancer Therapy and Resistance: Challenges and Opportunities

Article

Full-text available

Nov 2022
INT J MOL SCI

Resistance to chemo- and radiotherapy is a common event among cancer patients and a reason why new cancer therapies and therapeutic strategies need to be in continuous investigation and development. DNA damage response (DDR) comprises several pathways that eliminate DNA damage to maintain genomic stability and integrity, but different types of cancers are associated with DDR machinery defects. Many improvements have been made in recent years, providing several drugs and therapeutic strategies for cancer patients, including those targeting the DDR pathways. Currently, poly (ADP-ribose) polymerase inhibitors (PARP inhibitors) are the DDR inhibitors (DDRi) approved for several cancers, including breast, ovarian, pancreatic, and prostate cancer. However, PARPi resistance is a growing issue in clinical settings that increases disease relapse and aggravate patients’ prognosis. Additionally, resistance to other DDRi is also being found and investigated. The resistance mechanisms to DDRi include reversion mutations, epigenetic modification, stabilization of the replication fork, and increased drug efflux. This review highlights the DDR pathways in cancer therapy, its role in the resistance to conventional treatments, and its exploitation for anticancer treatment. Biomarkers of treatment response, combination strategies with other anticancer agents, resistance mechanisms, and liabilities of treatment with DDR inhibitors are also discussed.

3-Dimensional mesothelioma spheroids provide closer to natural pathophysiological tumor microenvironment for drug response studies

Article

Full-text available

Aug 2022

Traditional studies using cancer cell lines are often performed on a two-dimensional (2D) cell culture model with a low success rate of translating to Phase I or Phase II clinical studies. In comparison, with the advent of developments three-dimensional (3D) cell culture has been championed as the latest cellular model system that better mimics in vivo conditions and pathological conditions such as cancer. In comparison to biospecimens taken from in vivo tissue, the details of gene expression of 3D culture models are largely undefined, especially in mesothelioma – an aggressive cancer with very limited effective treatment options. In this study, we examined the veracity of the 3D mesothelioma cell culture model to study cell-to-cell interaction, gene expression and drug response from 3D cell culture, and compared them to 2D cell and tumor samples. We confirmed via SEM analysis that 3D cells grown using the spheroid methods expressed highly interconnected cell-to-cell junctions. The 3D spheroids were revealed to be an improved mini-tumor model as indicated by the TEM visualization of cell junctions and microvilli, features not seen in the 2D models. Growing 3D cell models using decellularized lung scaffold provided a platform for cell growth and infiltration for all cell types including primary cell lines. The most time-effective method was growing cells in spheroids using low-adhesive U-bottom plates. However, not every cell type grew into a 3D model using the the other methods of hanging drop or poly-HEMA. Cells grown in 3D showed more resistance to chemotherapeutic drugs, exhibiting reduced apoptosis. 3D cells stained with H&E showed cell-to-cell interactions and internal architecture that better represent that of in vivo patient tumors when compared to 2D cells. IHC staining revealed increased protein expression in 3D spheroids compared to 2D culture. Lastly, cells grown in 3D showed very different microRNA expression when compared to that of 2D counterparts. In conclusion, 3D cell models, regardless of which method is used. Showed a more realistic tumor microenvironment for architecture, gene expression and drug response, when compared to 2D cell models, and thus are superior preclinical cancer models.

Response to neoadjuvant chemotherapy in breast cancer: do microRNAs matter?

Article

Full-text available

Jun 2022

Background Conventionally, breast cancer (BC) prognosis and prediction of response to therapy are based on TNM staging, histological and molecular subtype, as well as genetic alterations. The role of various epigenetic factors has been elucidated in carcinogenesis. However, it is still unknown to what extent miRNAs affect the response to neoadjuvant chemotherapy (NACT). This pilot study is focused on evaluating the role of miR-34a, miR-124a, miR-155, miR-137 and miR-373 in response to NACT. Methods That was a prospective study enrolling 34 patients with histologically confirmed BC of II-III stages. The median age of patients was 53 (47-59.8) years old, 70.6% of whom were HR-positive. MiRs levels were measured in the primary tumor before and after NACT. The response to therapy was assessed after surgery using the Miller-Payne scoring system. To establish the role of miRs in modulating response to NACT the Cox model was applied for analysis. Results BC demonstrated a great variability of miRs expression before and after NACT with no strong links to tumor stage and molecular subtype. Only miR-124a and miR-373 demonstrated differential expression between malignant and normal breast tissues before and after therapy though these distinctions did not impact response to NACT. Besides miR-124a and miR-137 levels after NACT were found to be dependent on HR status. While miR-124a levels increased (p = 0.021) in the tumor tissue, the expression of miR-137 was downregulated (p = 0.041) after NACT in HR positive BC. Conclusions The study revealed differences in miR-124a and miR-373 expression after NACT in primary BC tissues. Although miRs levels did not impact the response to NACT, we found miR-124a and miR-137 levels to be related to hormonal sensitivity of BC.

MicroRNAs and Noncoding RNAs as Gene Regulators and Potential Therapeutic Agents

Chapter

May 2022

Breast cancer is highest prevailing cancer that incredibly affects women also globally it is the prominent reason of cancer-related mortality. The untranslated transcripts, called noncoding RNAs can be classified in short, mild, and long according to their length 19–31 nucleotides, 20–200 nucleotides, and >200 nucleotides, respectively. Among them, microRNAs are crucial in breast cancer. MicroRNAs efficient to regulate gene expression by regulating diverse cellular pathways. Breast cancer develops and progresses via either oncomiR (oncogenic miRNA) or else tsmiR (tumor suppressor miRNA). It is involved in certain regulatory pathways including PI3 kinases, Wnt/β-catenin, STAT, and HIF 1α which are hallmarks for tumor suppression or progression. MicroRNAs control the manifestation of multiple genes via sequence precise hybridization at 3′ untranslated region (UTR) of mRNAs. Expressively enhanced miRNAs manifestation is capable for alterations in cancer progression, initiation, invasion, migration, metastasis, and drug resistance. In the current scenario, miRNAs signature for drugs known as miRNA therapeutics is under investigation. Based upon the antisense technology very potential oligonucleotide targeted against miRNA which enhanced treatment effect of disease. miR-125b, miR-21, miR-155, and miR-145 frequently dysregulated and associated with the breast cancer. In future, miRNA-targeted therapeutics develop as a potential therapeutic as it is appropriate for delivery system of miRNA through improved efficacy and also specificity, miRNA-based therapeutics evolve on or after phase I/II to phase III. The present chapter will showcase combinatorial approaches with miRNAs therapy aimed at breast cancer.KeywordsBreast cancerNoncoding RNAmiRNAsGene regulationTherapeutic agent

The Role of Non-Coding RNAs in Breast Cancer Drug Resistance

Article

Full-text available

Sep 2021

Breast cancer (BC) is one of the commonly occurring malignancies in females worldwide. Despite significant advances in therapeutics, the mortality and morbidity of BC still lead to low survival and poor prognosis due to the drug resistance. There are certain chemotherapeutic, endocrine, and target medicines often used for BC patients, including anthracyclines, taxanes, docetaxel, cisplatin, and fluorouracil. The drug resistance mechanisms of these medicines are complicated and have not been fully elucidated. It was reported that non-coding RNAs (ncRNAs), such as micro RNAs (miRNA), long-chain non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) performed key roles in regulating tumor development and mediating therapy resistance. However, the mechanism of these ncRNAs in BC chemotherapeutic, endocrine, and targeted drug resistance was different. This review aims to reveal the mechanism and potential functions of ncRNAs in BC drug resistance and to highlight the ncRNAs as a novel target for achieving improved treatment outcomes for BC patients.

Smart co-delivery of miR-34a and cytotoxic peptides (LTX-315 and melittin) by chitosan based polyelectrolyte nanocarriers for specific cancer cell death induction

Article

Jun 2021
MAT SCI ENG C-BIO S

A novel polyelectrolyte nanocarrier was synthesized via layer-by-layer self-assembly of polycationic and polyanionic chains. The nanocarrier is composed of polyglutamate grafted chitosan core, dextran sulfate as a complexing agent, and polyethyleneimine shell decorated with folic acid. This polyelectrolyte complex has unique physicochemical properties so that the core is considered as an efficient carrier for LTX-315 and melittin peptides, and the shell is suitable for delivery of miR-34a. The spherical nanocarriers with an average size of 123 ± 5 nm and a zeta potential of −36 ± 1 mV demonstrated controlled-release of gene and peptides ensured a synergistic effect in establishing multiple cell death pathways on chemoresistance human breast adenocarcinoma cell line, MDA-MB-231. In vitro cell viability assays also revealed no cytotoxicity for the nanocarriers, and an IC50 of 15 μg/mL and 150 μg/mL for melittin and LTX-315, respectively, after 48 h, whereas co-delivery of melittin with miR-34a increased smart death induction by 54%.

Therapeutic strategies to overcome taxane resistance in cancer

Article

Feb 2021
DRUG RESIST UPDATE

One of the primary causes of attenuated or loss of efficacy of cancer chemotherapy is the emergence of multidrug resistance (MDR). Numerous studies have been published regarding potential approaches to reverse resistance to taxanes, including paclitaxel (PTX) and docetaxel, which represent one of the most important classes of anticancer drugs. Since 1984, following the FDA approval of paclitaxel for the treatment of advanced ovarian carcinoma, taxanes have been extensively used as drugs that target tumor microtubules. Taxanes, have been shown to affect an array of oncogenic signaling pathways and have potent cytotoxic efficacy. However, the clinical success of these drugs has been restricted by the e of cancer cell resistance, primarily caused by the overexpression of MDR efflux transporters or by microtubule alterations. In vitro and in vivo studies indicate that the mechanisms underlying the resistance to PTX and docetaxel are primarily due to alterations in α-tubulin and β-tubulin. Moreover, resistance to PTX and docetaxel results from: 1) alterations in microtubule-protein interactions, including microtubule-associated protein 4, stathmin, centriole, cilia, spindle-associated protein, and kinesins; 2) alterations in the expression and activity of multidrug efflux transporters of the ABC superfamily including P-glycoprotein (P-gp/ABCB1); 3) overexpression or inhibition of apoptotic proteins and tumor-suppressor proteins, as well as 4) modulation of signal transduction pathways associated with the activity of several cytokines, chemokines and transcription factors. In this review, we discuss the above-mentioned molecular mechanisms and their role in mediating cancer chemoresistance to PTX and docetaxel. We provide a detailed analysis of both in vitro and in vivo experimental data and describe the application of these findings to therapeutic practice. The current review also discusses the efficacy of different pharmacological modulations to achieve reversal of PTX resistance. The therapeutic roles of several novel compounds, as well as herbal formulations, are also discussed. Among them, many structural derivatives had efficacy in the MDR phenotype by either suppressing MDR or increasing the cytotoxic efficacy compared to the parental drugs, or both. Natural products functioning as MDR chemosensitizers offer novel treatment strategies in patients with chemoresistant cancers attenuating the effects of MDR and increasing chemotherapy efficacy. We broadly discuss the roles of P-gp and other efflux pump inhibitors, in the reversal of PTX and docetaxel resistance in cancer cells and the significance of using a nanomedicine delivery system in this context. Thus, a better understanding of the molecular mechanisms mediating the reversal of drug resistance, combined with drug efficacy and the application of target-based inhibition or specific drug delivery, could signal a new era in modern medicine that would limit the pathological consequences of MDR in cancer patients.

Flavonoid display ability to target microRNAs in cancer pathogenesis

Article

Jan 2021
BIOCHEM PHARMACOL

MicroRNAs (miRNAs) are non-coding, conserved, single-stranded nucleotide sequences involved in physiological and developmental processes. Recent evidence suggests an association between miRNAs' deregulation with initiation, promotion, progression, and drug resistance in cancer cells. Besides, miRNAs are known to regulate the epithelial-mesenchymal transition, angiogenesis, autophagy, and senescence in different cancer types. Previous reports proposed that apart from the antioxidant potential, flavonoids play an essential role in miRNA modulation associated with changes in cancer-related proteins, tumor suppressor genes, and oncogenes. Thus, flavonoids can suppress proliferation, help in the development of drug sensitivity, suppress metastasis and angiogenesis by modulating miRNA expression. In the present review, we summarize the role of miRNA in cancer, drug resistance, and the chemopreventive potential of flavonoids mediated by miRNAs. The potential of flavonoids to modulate miRNA expression in different cancer types demonstrates their selectivity and importance as regulators of carcinogenesis. Flavonoids as chemopreventive agents targeting miRNAs are extensively studied in vitro, in vivo, and pre-clinical studies, but their efficiency in targeting miRNAs in clinical studies is less investigated. The evidence presented in this review highlights the potential of flavonoids in cancer prevention/treatment by regulating miRNAs, although further investigations are required to validate and establish their clinical usefulness.

Aberrantly up-regulated miR-142-3p inhibited the proliferation and invasion of trophoblast cells by regulating FOXM1

Article

Jan 2021
PLACENTA

Introduction Preeclampsia is one of the main causes of morbidity and mortality in pregnant women and mothers. Numerous studies showed that microRNAs (miRNAs) played important roles in the occurrence and development of preeclampsia. However, the regulation of microRNA-142-3p (miR-142-3p) in preeclampsia has not been clarified. Methods The expression of miR-142-3p and FOXM1 was detected by RT-qPCR. The interaction between miR-142-3p and FOXM1 was confirmed by dual-luciferase reporter assay. The relative protein expression of FOXM1 was measured by western blot. Cell proliferation was measured using MTT assay. Cell migration was detected using transwell assay and wound healing assay. Results The expression of miR-142-3p was up-regulated, while the mRNA and protein of FOXM1 expression were down-regulated in preeclampsia tissues. Additionally, we found that miR-142-3p targeted FOXM1. Moreover, FOXM1 expression was negatively regulated by miR-142-3p. Functional experiments showed that overexpression of miR-142-3p inhibited cell growth and migration in trophoblast cells. Reverse experiments determined that overexpression of FOXM1 reversed the suppressive effects of miR-142-3p on cell proliferation and migration. Discussion Our results demonstrated that miR-142-3p regulated cell proliferation and migration through targeting FOXM1 in trophoblast cells, providing a novel therapeutic target and extending the pathogenesis of preeclampsia.

Functional roles of exosomal miRNAs in multi-drug resistance in cancer chemotherapeutics

Article

Dec 2020

Recent understanding of different molecular aspects of tumor initiation and progression has led to the discovery of a growing list of drugs. While these drugs have shown promising effects on tumor cells, their widespread usage has been hampered by the acquisition of drug resistance in a subpopulation of tumor cells. A differential pattern in the secretion of specialized vesicles named “exosomes” in drug-resistant cancer cells have recently received much attention. In addition, microRNAs (miRNAs) have been shown to be enriched in exosomes. Exosomal miRNAs (also known as exo-miRs) could be shuttled to recipient cells and play a role in the regulation of post-transcriptional gene expression, which may exert certain effects on cancer drug resistance. Here, we have reviewed the role of exo-miRs in chemotherapeutic resistance in different cancer types. Besides, studies which have focused on predictive role of circulating exo-miRs in cancer drug resistance are reviewed.

Nanoliposomes as Multidrug Carrier of Gemcitabine/Paclitaxel for the Effective Treatment of Metastatic Breast Cancer Disease: A Comparison with Gemzar and Taxol

Article

Full-text available

Sep 2020

Several liposomal drugs have received clinical approval for the treatment of cancer due to the reduced side effects and/or improved therapeutic efficacy in comparison to their respective free drug counterparts. In this study, nanoliposomes are designed as multidrug carriers for codelivering gemcitabine hydrochloride (Gemzar) and paclitaxel (Taxol) and evaluating their anticancer activity in several triple negative human breast cancer cell lines and in a mouse model of metastatic breast cancer. The results demonstrate that the nanoliposomes significantly decrease the cell viability of breast cancer cells compared to combination treatment with the free drugs. Furthermore, the chemotherapeutics coloaded nanoliposomes dramatically decrease the tumor growth and improve survival times, while combination treatment with Gemzar and Taxol has a modest effect on cancer progression. Moreover, pharmacokinetic analysis demonstrates that nanoliposomes increase the half‐life of gemcitabine hydrochloride and paclitaxel 6.3‐fold and 1.7‐fold, respectively. Taken together, the findings indicate that gemcitabine hydrochloride and paclitaxel‐coloaded nanoliposomes can provide an effective treatment strategy for metastatic breast cancer.

Non-Coding RNAs as Regulators and Markers for Targeting of Breast Cancer and Cancer Stem Cells

Article

Full-text available

Feb 2020

Breast cancer is regarded as a heterogeneous and complicated disease that remains the prime focus in the domain of public health concern. Next-generation sequencing technologies provided a new perspective dimension to non-coding RNAs, which were initially considered to be transcriptional noise or a product generated from erroneous transcription. Even though understanding of biological and molecular functions of noncoding RNA remains enigmatic, researchers have established the pivotal role of these RNAs in governing a plethora of biological phenomena that includes cancer-associated cellular processes such as proliferation, invasion, migration, apoptosis, and stemness. In addition to this, the transmission of microRNAs and long non-coding RNAs was identified as a source of communication to breast cancer cells either locally or systemically. The present review provides in-depth information with an aim at discovering the fundamental potential of non-coding RNAs, by providing knowledge of biogenesis and functional roles of micro RNA and long non-coding RNAs in breast cancer and breast cancer stem cells, as either oncogenic drivers or tumor suppressors. Furthermore, non-coding RNAs and their potential role as diagnostic and therapeutic moieties have also been summarized.

The Bcl-2 protein: a prognostic indicator strongly related to ER and PR in breast cancer

Article

Full-text available

Oct 2004

Bcl-2, the protein product of the Bcl-2 gene, is a member of the Bcl-2 family of proteins that play a crucial role in a complex mechanism of apoptosis. It was recently proposed that bcl-2 could inhibit cancer progression. In this study, we evaluated the expression patterns of Bcl-2, estrogen receptors (ER), progesterone receptors (PR) in 71 primary invasive breast carcinomas and their association with other clinicopathological parameters. Samples from 71 patients with invasive breast cancer with follow-up ranging from 4-103 months (median 57 months) were included in the study. Forty-six patients (66%) obtained a complete response, while 5 (9%) were considered non-responders during the follow up period of 103 months. Eighteen (25%) patients died, 15 (21%) from primary disease and 3 (4%) from other disease. In unvaried analysis, tumor size (<2 cm), lymph node (<4 lymph nodes), hormonal status and Bcl-2 expression are correlated with longer overall (OS) and relapse-free survival (RFS). Patients with 4 or more positive axillary lymph nodes had significantly shorter OS (p=0.01) and RFS (p=0.009). Higher expression of Bcl-2 was associated with longer OS (p=0.02) and RFS (p=0.03), and this result were independent of axillary lymph nodes and tumor size in Cox multivariate analysis.

Liu Q, Fu H, Sun F, Zhang H, Tie Y, Zhu J, Xing R, Sun Z, Zheng XmiR-16 family induces cell cycle arrest by regulating multiple cell cycle genes. Nucleic Acids Res 36: 5391-5404

Article

Full-text available

Aug 2008
NUCLEIC ACIDS RES

MicroRNAs (miRNAs) are a class of small regulatory RNAs that are thought to be involved in diverse biological processes by regulating gene expression. Numerous miRNAs have been identified in various species, and many more miRNAs remain to be detected. Generally, hundreds of mRNAs have been predicted to be potential targets of one miRNA, so it is a great challenge to identify the genuine miRNA targets. Here, we generated the cell lines depleted of Drosha protein and screened dozens of transcripts (including Cyclin D1) regulated potentially by miRNA-mediated RNA silencing pathway. On the basis of miRNA expressing library, we established a miRNA targets reverse screening method by using luciferase reporter assay. By this method, we found that the expression of Cyclin D1 (CCND1) was regulated by miR-16 family directly, and miR-16 induced G1 arrest in A549 cells partially by CCND1. Furthermore, several other cell cycle genes were revealed to be regulated by miR-16 family, including Cyclin D3 (CCND3), Cyclin E1 (CCNE1) and CDK6. Taken together, our data suggests that miR-16 family triggers an accumulation of cells in G0/G1 by silencing multiple cell cycle genes simultaneously, rather than the individual target.

p53 mutation and cyclin D1 amplification correlate to cisplatin sensitivity in xenografted human squamous cell carcinoma of the head and neck

Article

Full-text available

Feb 2006

To investigate the response of tumour growth to cisplatin treatment, in relation to p53 mutation and cyclin D1 dysregulation on DNA and protein level, biopsies from seven xenografted human squamous cell carcinomas from the head and neck were analysed with immunohistochemistry for p53 expression and cyclin D1 expression. Polymerase chain reaction-singlestranded conformation polymorphism was used to determine p53 mutations. Fluorescence in situ hybridization was performed to analyse cyclin D1 amplification. The mice were injected i.p. with NaCl (controls) or cisplatin. After injection the tumour volume were measured. The inhibition of tumour growth by cisplatin was defined as the area under the growth curves, and compared with the growth curves of the tumours in the control group. Xenografts with p53 mutation showed significantly higher resistance to cisplatin (p < 0.001) and also tumours with cyclin D1 amplification showed significantly higher resistance (p < 0.001).

Oncomirs: MicroRNAs with a role in cancer

Article

Full-text available

Apr 2006
CANCER-AM CANCER SOC

MicroRNAs (miRNAs) are an abundant class of small non-protein-coding RNAs that function as negative gene regulators. They regulate diverse biological processes, and bioinformatic data indicates that each miRNA can control hundreds of gene targets, underscoring the potential influence of miRNAs on almost every genetic pathway. Recent evidence has shown that miRNA mutations or mis-expression correlate with various human cancers and indicates that miRNAs can function as tumour suppressors and oncogenes. miRNAs have been shown to repress the expression of important cancer-related genes and might prove useful in the diagnosis and treatment of cancer.

Downregulation of miR-21 Enhances Chemotherapeutic Effect of Taxol in Breast Carcinoma Cells

Article

Full-text available

Feb 2010
TECHNOL CANCER RES T

The successful of anti-cancer treatment are often limited by the development of drug resistance. Recent work has highlighted the involvement of non-coding RNAs, microRNAs(miRNAs) in cancer development, and their possible involvement in the evolution of drug resistance has been proposed. In this study, we combine taxol chemotherapy and miR-21 inhibitor treatment via polyamidoamine (PAMAM) dendrimers vector to evaluate the effects of combination therapy on suppression of breast cancer cells. The 50% inhibitory concentration (IC50) values for taxol were significantly decreased to a greater extent in the cells transfected with miR-21 inhibitor compared with cells treated with taxol alone. Taxol treatment also increased the percentage of apoptotic breast cancer cells in miR-21 inhibitor transfected cells compared with control cells. Furthermore, treatment of the miR-21 inhibitor-transfected cells with the anti-cancer drugs taxol resulted in significantly reduced cell viability and invasiveness compared with control cells. These results indicated that the miR-21 plays an important role in the resistance of breast carcinoma cells to chemotherapeutic drugs. Therefore, miR-21 inhibitor gene therapy combined with taxol chemotherapy might represent a promising novel therapeutic approach for the treatment of breast malignancies.

Molecular and cell cycle in MCF-7 cells resistant to cisplatin and doxorubicin

Article

Full-text available

Jul 2009

To compare ultrastructure, phenotypic profile and cell cycle progression of MCF-7 human breast cancer cells and MCF7 sublines resistant to cisplatin (MCF-7/DDP) and doxorubicin (MCF-7/DOX). MTT-test, immunocytochemistry, flow cytometry, electron microscopy. The development of drug resistance to cisplatin and doxorubicin in MCF-7 cells upon the culturing of the initial cells with the raising concentrations of cytostatics was accompanied by the increase in cells adhesion, the increasing differentiation grade and the loss of steroid hormone receptors. Besides, it was shown that antiapoptotic mechanisms (decrease of Bcl-2 expression) and intracellular glutathione detoxifying system are involved in the process of cisplatin resistance development in MCF-7 cells. At the same time, P-glycoprotein overexpression in cells resistant to doxorubicin suggests MDR-dependent mechanism. Both doxorubicin- and cisplatin-resistant cells are characterized by the changes in the expression of several cell cycle regulators -- Ki-67, cyclin D1, pRb and p21). The long-time culture of MCF-7 cells with cytostatic drugs results in the decreased cyclin D1, pRb, and Ki-67 expression and increased p21 expression with the increasing differentiation grade of the resistant cells. The underlying mechanisms of resistance to cisplatin and doxorubicin in MCF-7 cells may be different.

MicroRNA-328 Negatively Regulates the Expression of Breast Cancer Resistance Protein (BCRP/ABCG2) in Human Cancer Cells

Article

Full-text available

Apr 2009
MOL PHARMACOL

Breast cancer resistance protein (BCRP/ABCG2) is a molecular determinant of pharmacokinetic properties of many drugs in humans. To understand post-transcriptional regulation of ABCG2 and the role of microRNAs (miRNAs) in drug disposition, we found that microRNA-328 (miR-328) might readily target the 3'-untranslated region (3'-UTR) of ABCG2 when considering target-site accessibility. We then noted 1) an inverse relation between the levels of miR-328 and ABCG2 in MCF-7 and MCF-7/MX100 breast cancer cells and 2) that miR-328 levels could be rescued in MCF-7/MX100 cells by transfection with miR-328 plasmid. Luciferase reporter assays showed that ABCG2 3'-UTR-luciferase activity was decreased more than 50% in MCF-7/MX100 cells after transfection with miR-328 plasmid, the activity was increased over 100% in MCF-7 cells transfected with a miR-328 antagomir, and disruption of miR-328 response element within ABCG2 3'-UTR led to a 3-fold increase in luciferase activity. Furthermore, the level of ABCG2 protein was down-regulated when miR-328 was over-expressed, and the level was up-regulated when miR-328 was inhibited by selective antagomir. Altered ABCG2 protein expression was associated with significantly declined or elevated levels of ABCG2 3'-UTR and coding sequence mRNAs, suggesting possible involvement of the mechanism of mRNA cleavage. Finally, miR-328-directed down-regulation of ABCG2 expression in MCF-7/MX100 cells resulted in an increased mitoxantrone sensitivity, as manifested by a significantly lower IC(50) value (2.46 +/- 1.64 microM) compared with the control (151 +/- 32 microM). Together, these findings suggest that miR-328 targets ABCG2 3'-UTR and, consequently, controls ABCG2 protein expression and influences drug disposition in human breast cancer cells.

Regulation of Epidermal Growth Factor Receptor Signaling in Human Cancer Cells by MicroRNA-7

Article

Full-text available

Feb 2009

The epidermal growth factor receptor (EGFR) is frequently overexpressed in cancer and is an important therapeutic target. Aberrant expression and function of microRNAs have been associated with tumorigenesis. Bioinformatic predictions suggest that the human EGFR mRNA 3'-untranslated region contains three microRNA-7 (miR-7) target sites, which are not conserved across mammals. We found that miR-7 down-regulates EGFR mRNA and protein expression in cancer cell lines (lung, breast, and glioblastoma) via two of the three sites, inducing cell cycle arrest and cell death. Because miR-7 was shown to decrease EGFR mRNA expression, we used microarray analysis to identify additional mRNA targets of miR-7. These included Raf1 and multiple other genes involved in EGFR signaling and tumorigenesis. Furthermore, miR-7 attenuated activation of protein kinase B (Akt) and extracellular signal-regulated kinase 1/2, two critical effectors of EGFR signaling, in different cancer cell lines. These data establish an important role for miR-7 in controlling mRNA expression and indicate that miR-7 has the ability to coordinately regulate EGFR signaling in multiple human cancer cell types.

miR-34a inhibits migration and invasion by down-regulation of c-Met expression in human hepatocellular carcinoma cells

Article

Full-text available

Dec 2008

Several studies have shown that miR-34a represses the expression of many genes and induces G1 arrest, apoptosis, and senescence. In the present study, we identified the role of miR-34a in the regulation of tumor cell scattering, migration, and invasion. Down-regulation of miR-34a expression was highly significant in 19 of 25 (76%) human hepatocellular carcinoma (HCC) tissues compared with adjacent normal tissues and associated with the metastasis and invasion of tumors. Furthermore, resected normal/tumor tissues of 25 HCC patients demonstrated an inverse correlation between miR-34a and c-Met-protein. In HepG2 cells, ectopic expression of miR-34a potently inhibited tumor cell migration and invasion in a c-Met-dependent manner. miR-34a directly targeted c-Met and reduced both mRNA and protein levels of c-Met; thus, decreased c-Met-induced phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2). Taken together, these results provide evidence to show the suppression role of miR-34a in tumor migration and invasion through modulation of the c-Met signaling pathway.

MiR-34a repression of SIRT1 regulates apoptosis

Article

Full-text available

Oct 2008
P NATL ACAD SCI USA

MicroRNA 34a (miR-34a) is a tumor suppressor gene, but how it regulates cell proliferation is not completely understood. We now show that the microRNA miR-34a regulates silent information regulator 1 (SIRT1) expression. MiR-34a inhibits SIRT1 expression through a miR-34a-binding site within the 3′ UTR of SIRT1. MiR-34 inhibition of SIRT1 leads to an increase in acetylated p53 and expression of p21 and PUMA, transcriptional targets of p53 that regulate the cell cycle and apoptosis, respectively. Furthermore, miR-34 suppression of SIRT1 ultimately leads to apoptosis in WT human colon cancer cells but not in human colon cancer cells lacking p53. Finally, miR-34a itself is a transcriptional target of p53, suggesting a positive feedback loop between p53 and miR-34a. Thus, miR-34a functions as a tumor suppressor, in part, through a SIRT1-p53 pathway. • microRNA • p53 • cancer

MicroRNA-221/222 Confers Tamoxifen Resistance in Breast Cancer by Targeting p27Kip1

Article

Full-text available

Aug 2008

We explored the role of microRNAs (miRNAs) in acquiring resistance to tamoxifen, a drug successfully used to treat women with estrogen receptor-positive breast cancer. miRNA microarray analysis of MCF-7 cell lines that are either sensitive (parental) or resistant (4-hydroxytamoxifen-resistant (OHTR)) to tamoxifen showed significant (>1.8-fold) up-regulation of eight miRNAs and marked down-regulation (>50%) of seven miRNAs in OHTR cells compared with parental MCF-7 cells. Increased expression of three of the most promising up-regulated (miR-221, miR-222, and miR-181) and down-regulated (miR-21, miR-342, and miR-489) miRNAs was validated by real-time reverse transcription-PCR. The expression of miR-221 and miR-222 was also significantly (2-fold) elevated in HER2/neu-positive primary human breast cancer tissues that are known to be resistant to endocrine therapy compared with HER2/neu-negative tissue samples. Ectopic expression of miR-221/222 rendered the parental MCF-7 cells resistant to tamoxifen. The protein level of the cell cycle inhibitor p27Kip1, a known target of miR-221/222, was reduced by 50% in OHTR cells and by 28–50% in miR-221/222-overexpressing MCF-7 cells. Furthermore, overexpression of p27Kip1 in the resistant OHTR cells caused enhanced cell death when exposed to tamoxifen. This is the first study demonstrating a relationship between miR-221/222 expression and HER2/neu overexpression in primary breast tumors that are generally resistant to tamoxifen therapy. This finding also provides the rationale for the application of altered expression of specific miRNAs as a predictive tamoxifen-resistant breast cancer marker.

Multivariate Analysis of Bcl-2, Apoptosis, P53, And Her-2/Neu In Breast Cancer: A Short Term Follow Up

Article

Full-text available

Jul 2002

Several molecular genetic alterations in breast cancer, including aneuploidy, altered apoptosis, aberrant expression of p53, HER-2/neu and Bcl-2, have been associated with poor prognosis in breast cancer patients. To determine the importance of molecular-genetic factors relative to more traditional surgical-pathological prognostic factors, multivariate analysis was performed. Ninety-four fresh tissue samples of primary breast carcinoma were studied with flow cytometry for DNA ploidy. On the same specimens, steroid hormone receptors (ER and PR) were measured in the cytosol fraction using Abbott ELISA assays. HER-2/neu was determined in the membrane fraction and mutant p53 protein in the nuclear fraction, both, by Oncogene Science ELIZA procedures. Bcl-2 and apoptosis (cell death) were measured in cell lysates by Oncogene Science & Boehringer Mannheim ELISA assays. In addition, information regarding surgical-pathological features of the tumor was obtained. Multivariate analysis using an unconditional logistic regression model was done to identify variables predictive of poor prognosis. Using univariate analysis, histological grade, tumor stage, lymph node status, HER-2/neu and mutant p53 were predictive of poor short-term prognosis. By multivariate analysis, tumor stage, lymph node status and HER-2/neu were independent factors. Grade subgroup analysis versus time of relapse, illustrated a predictive value of Bcl-2 in only low-grade tumors while apoptosis was significant in high-grade type. Among a panel of molecular-genetic factors investigated, HER-2/neu was the most strongly predictive of poor short-term prognosis in breast cancer. Patients with HER-2/neu-positive tumors can benefit from Herceptin therapy.

Expression patterns of cell cycle and apoptosis-related genes in a multidrug-resistant human colon carcinoma cell line

Article

Full-text available

Jun 2004

An in vitro multidrug resistance (MDR) system from a human colonic cancer cell line (SW620-MDR) has been established. To further study the mechanisms at molecular level and prevention of multidrug resistance in clinical practice, it was demonstrated that the expressions of several apoptosis-related and cell cycle regulator genes were changed in the cells. A multidrug-resistant colonic cell line (SW620-MDR) was established, and the Atlas human cDNA expression array was used for studying the pattern of gene expression in this cell line. Furthermore, Northern hybridization or real-time PCR analysis confirmed the pattern of gene expression. In the SW620-MDR cell line the pro-apoptosis genes, CASP4, BIK, PDCD2, and TACE were expressed with decreased levels, and the antiapoptosis genes CD27-L and IGFBP2 were over-expressed. Furthermore, the cell cycle regulator genes such as CDK6, CCND1, CDC27HS, CDC16HS, Wee1Hu, MAPKK1, and IGFBP6 were expressed with decreased levels in the drug-resistant cell line. It is worthwhile investigating whether the differentially expressed pattern of the aforementioned genes exists in the drug-resistant cancer specimens, and to further understand their functions in the cancer drug-resistance mechanism.

Reduced expression of p27 is a novel mechanism of docetaxel resistance in breast cancer cells

Article

Full-text available

Feb 2004

Docetaxel is one of the most effective chemotherapeutic agents in the treatment of breast cancer. Breast cancers can have an inherent or acquired resistance to docetaxel but the causes of this resistance remain unclear. However, apoptosis and cell cycle regulation are key mechanisms by which most chemotherapeutic agents exert their cytotoxic effects. We created two docetaxel-resistant human breast cancer cell lines (MCF-7 and MDA-MB-231) and performed cDNA microarray analysis to identify candidate genes associated with docetaxel resistance. Gene expression changes were validated at the RNA and protein levels by reverse transcription PCR and western analysis, respectively. Gene expression cDNA microarray analysis demonstrated reduced p27 expression in docetaxel-resistant breast cancer cells. Although p27 mRNA expression was found to be reduced only in MCF-7 docetaxel-resistant sublines (2.47-fold), reduced expression of p27 protein was noted in both MCF-7 and MDA-MB-231 docetaxel-resistant breast cancer cells (2.83-fold and 3.80-fold, respectively). This study demonstrates that reduced expression of p27 is associated with acquired resistance to docetaxel in breast cancer cells. An understanding of the genes that are involved in resistance to chemotherapy may allow further development in modulating drug resistance, and may permit selection of those patients who are most likely to benefit from such therapies.

Overexpression of Cyclin D1 Promotes Tumor Cell Growth and Confers Resistance to Cisplatin-Mediated Apoptosis in an Elastase-myc Transgene-Expressing Pancreatic Tumor Cell Line

Article

Full-text available

Sep 2005

Elevated cyclin D1 in human pancreatic cancer correlates with poor prognosis. Because pancreatic cancer is invariably resistant to chemotherapy, the goal of this study was to examine whether the drug resistance of pancreatic cancer cells is in part attributed to cyclin D1 overexpression. Stable overexpression and small interfering RNA (siRNA)--mediated knockdown of cyclin D1 were done in the newly established Ela-myc pancreatic tumor cell line. Cisplatin sensitivity of control, overexpressing, and siRNA-transfected cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, clonogenic, and apoptotic assays [DNA fragmentation, sub-G1, and poly(ADP-ribose) polymerase cleavage analysis]. The role of nuclear factor-kappaB and apoptotic proteins in cyclin D1-mediated chemoresistance was examined by EMSA and Western blotting, respectively. Overexpression of cyclin D1 in Ela-myc pancreatic tumor cells promoted cell proliferation and anchorage-independent growth. Moreover, cyclin D1-overexpressing cells exhibited significantly reduced chemosensitivity and a higher survival rate upon cisplatin treatment, as determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and clonogenic assays, respectively. Although overexpression of cyclin D1 rendered cells more resistant to cisplatin-induced apoptosis, siRNA-directed suppression of cyclin D1 expression resulted in enhanced susceptibility to cisplatin-mediated apoptosis. The attenuation of cisplatin-induced cell death in cyclin D1-overexpressing cells was correlated with the up-regulation of nuclear factor-kappaB activity and maintenance of bcl-2 and bcl-xl protein levels. These results suggest that overexpression of cyclin D1 can contribute to chemoresistance of pancreatic cancer cells because of the dual roles of cyclin D1 in promoting cell proliferation and in inhibiting drug-induced apoptosis.

MiR-15 and miR-16 induce apoptosis by targeting BCL2

Article

Full-text available

Oct 2005

Chronic lymphocytic leukemia (CLL) is the most common human leukemia and is characterized by predominantly nondividing malignant B cells overexpressing the antiapoptotic B cell lymphoma 2 (Bcl2) protein. miR-15a and miR-16-1 are deleted or down-regulated in the majority of CLLs. Here, we demonstrate that miR-15a and miR-16-1 expression is inversely correlated to Bcl2 expression in CLL and that both microRNAs negatively regulate Bcl2 at a posttranscriptional level. BCL2 repression by these microRNAs induces apoptopsis in a leukemic cell line model. Therefore, miR-15 and miR-16 are natural antisense Bcl2 interactors that could be used for therapy of Bcl2-overexpressing tumors.

Esquela-Kerscher, A and Slack, FJ. Oncomirs-microRNAs with a role in cancer. Nat Rev Cancer 6: 259-269

Article

Full-text available

May 2006
NAT REV CANCER

Identification of genes associated with cisplatin resistance in human oral squamous cell carcinoma cell line

Article

Full-text available

Feb 2006
BMC CANCER

Cisplatin is widely used for chemotherapy of head and neck squamous cell carcinoma. However, details of the molecular mechanism responsible for cisplatin resistance are still unclear. The aim of this study was to identify the expression of genes related to cisplatin resistance in oral squamous cell carcinoma cells. A cisplatin-resistant cell line, Tca/cisplatin, was established from a cisplatin-sensitive cell line, Tca8113, which was derived from moderately-differentiated tongue squamous cell carcinoma. Global gene expression in this resistant cell line and its sensitive parent cell line was analyzed using Affymetrix HG-U95Av2 microarrays. Candidate genes involved in DNA repair, the MAP pathway and cell cycle regulation were chosen to validate the microarray analysis results. Cell cycle distribution and apoptosis following cisplatin exposure were also investigated. Cisplatin resistance in Tca/cisplatin cells was stable for two years in cisplatin-free culture medium. The IC50 for cisplatin in Tca/cisplatin was 6.5-fold higher than that in Tca8113. Microarray analysis identified 38 genes that were up-regulated and 25 that were down-regulated in this cell line. Some were novel candidates, while others are involved in well-characterized mechanisms that could be relevant to cisplatin resistance, such as RECQL for DNA repair and MAP2K6 in the MAP pathway; all the genes were further validated by Real-time PCR. The cell cycle-regulated genes CCND1 and CCND3 were involved in cisplatin resistance; 24-hour exposure to 10 microM cisplatin induced a marked S phase block in Tca/cisplatin cells but not in Tca8113 cells. The Tca8113 cell line and its stable drug-resistant variant Tca/cisplatin provided a useful model for identifying candidate genes responsible for the mechanism of cisplatin resistance in oral squamous cell carcinoma. Our data provide a useful basis for screening candidate targets for early diagnosis and further intervention in cisplatin resistance.

Coordinate suppression of ERBB2 and ERBB3 by enforced expression of micro-RNA miR-125a or miR-125b

Article

Full-text available

Feb 2007

Deregulation of micro-RNAs (miRNAs) is emerging as a major aspect of cancer etiology because their capacity to direct the translation and stability of targeted transcripts can dramatically influence cellular physiology. To explore the potential of exogenously applied miRNAs to suppress oncogenic proteins, the ERBB oncogene family was chosen with a bioinformatics search identifying targeting seed sequences for miR-125a and miR-125b within the 3′-untranslated regions of both ERBB2 and ERBB3. Using the human breast cancer cell line SKBR3 as a model for ERBB2 and ERBB3 dependence, infection of these cells with retroviral constructs expressing either miR-125a or miR-125b resulted in suppression of ERBB2 and ERBB3 at both the transcript and protein level. Luciferase constructs containing the 3′ 3′-untranslated regions of ERBB2 and ERBB3 demonstrated ∼35% less activity in miR-125a- and miR-125b-expressing cells relative to controls. Additionally, phosphorylation of ERK1/2 and AKT was suppressed in SKBR3 cells overexpressing either miR-125a or miR-125b. Consistent with suppression of both ERBB2 and ERBB3 signaling, miR-125a-or miR-125b-overexpressing SKBR3 cells were impaired in their anchorage-dependent growth and exhibited reduced migration and invasion capacities. Parallel studies performed on MCF10A cells demonstrated that miR-125a or miR-125b overexpression produced only marginal influences on the growth and migration of these non-transformed human mammary epithelial cells. These results illustrate the feasibility of using miRNAs as a therapeutic strategy to suppress oncogene expression and function.

bcl-2, p53, and response to tamoxifen in estrogen receptor-positive metastatic breast cancer: a Southwest Oncology Group study

Article

May 1997

Purpose: To test the hypothesis that high bcl-2 expression and accumulation of p53 protein, both of which should inhibit apoptosis, are associated with a poorer tamoxifen response and a more aggressive clinical course in estrogen receptor (ER)-positive metastatic breast cancer. Methods: A total of 205 paraffin-embedded tumor blocks were evaluated for nuclear p53 (a marker of p53 inactivation) and cytoplasmic bcl-2 by immunohistochemistry (IHC). All patients received tamoxifen as initial therapy for metastatic disease. The study began in 1982 and follow-up duration of the 24 patients last known alive is 8 years. Results: Response to tamoxifen and time to treatment failure (TTF) were not significantly associated with p53 status, although patients with higher p53 had a worse survival (P = .008; median, 36 v 20 months). Higher bcl-2 expression was associated with higher levels of ER (P = .02), better response to tamoxifen (62% v 49%; P = .07), longer TTF (median, 9 v 5 months; P = .002), and better survival (median, 40 months v 25 months; P = .009). In multivariate analyses, including ER, progesterone receptor (PgR), and p53, high bcl-2 remained significantly associated with a longer TTF (P = .007) and survival (P = .07). p53 status was a significant factor for shorter survival (P = .05), but not for TTF (P = .61). Conclusion: p53 status, as determined by IHC is not significantly associated with response to tamoxifen, although tumors with altered p53 protein are inherently more aggressive. Contrary to expectation, high bcl-2 identifies a relatively indolent phenotype of ER-positive metastatic breast cancer, in which patients experience a better clinical response to tamoxifen and a longer survival.

miR-15b and miR-16 modulate multidrug resistance by targeting BCL2 in human gastric cancer cells

Article

Jul 2008
INT J CANCER

microRNAs are endogenous small noncoding RNAs that regulate gene expression negatively at posttranscriptional level. This latest addition to the complex gene regulatory circuitry revolutionizes our way to understanding physiological and pathological processes in the human body. Here we investigated the possible role of microRNAs in the development of multidrug resistance (MDR) in gastric cancer cells. microRNA expression profiling revealed a limited set of microRNAs with altered expression in multidrug- resistant gastric cancer cell line SGC7901/VCR compared to its parental SGC7901 cell line. Among the downregulated microRNAs are miR-15b and miR-16, members of miR-15/16 family, whose expression was further validated by qRT-PCR. In vitro drug sensitivity assay demonstrated that overexpression of miR-15b or miR-16 sensitized SGC7901/VCR cells to anticancer drugs whereas inhibition of them using antisense oligonucleotides conferred SGC7901 cells MDR. The downregulation of miR-15b and miR-16 in SGC7901/VCR cells was concurrent with the upregulation of Bcl-2 protein. Enforced mir-15b or miR-16 expression reduced Bcl-2 protein level and the luciferase activity of a BCL2 3' untranslated region-based reporter construct in SGC7901/VCR cells, suggesting that BCL2 is a direct target of miR-15b and miR-16. Moreover, overexpression of miR-15b or miR-16 could sensitize SGC7901/VCR cells to VCR-induced apoptosis. Taken together, our findings suggest that miR-15b and miR-16 could play a role in the development of MDR in gastric cancer cells at least in part by modulation of apoptosis via targeting BCL2.

Article p53-Mediated Activation of miRNA34 Candidate Tumor-Suppressor Genes

Article

Jan 2007
CURR BIOL

Summary

Modulation of tamoxifen sensitivity by antisense Bcl‐2 and trastuzumab in breast carcinoma cells

Article

May 2005
CANCER-AM CANCER SOC

Because the overexpression of HER-2 and Bcl-2 is associated with resistance to tamoxifen (TAM), the authors examined the effect of antisense (AS) Bcl-2 on sensitivity to TAM compared with the effect of trastuzumab on sensitivity to TAM in breast carcinoma cell lines. Drug sensitivity was assessed in vitro using a [3-4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay with the breast carcinoma cell lines ZR-75-1, MDA-MB-453, and BT-474. AS Bcl-2 18-mer phosphorothioate oligonucleotide was applied. Apoptotic cell death was assessed with the terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick-end labeling method, and gene expression was evaluated with Western blot analysis. The expression of Bcl-2 was identified in ZR-75-1 and BT-474 cells and, to a lesser extent, in MDA-MB-453 cells. Overexpression of HER-2 was identified in BT-474 cells, and moderate expression was identified in MDA-MB-453 and ZR-75-1 cells. Combination treatment with trastuzumab or AS Bcl-2 enhanced TAM sensitivity in ZR-75-1 cells, which showed 50% inhibitory concentration (IC50) values of 0.9 μM (7.2-fold increase) and 0.5 μM (13.0-fold), respectively. Combination treatment with trastuzumab or AS Bcl-2 slightly enhanced TAM sensitivity of BT-474 cells, with IC50 values of 3.0 μM (1.3-fold) and 1.5 μM (2.6-fold), respectively. The sensitivity of MDA-MB-453 cells to TAM was not enhanced by combination with trastuzumab or AS Bcl-2. Modulation of TAM sensitivity by AS Bcl-2 was superior to modulation by trastuzumab in HER-2-expressing and Bcl-2-expressing breast carcinoma cells. Enhanced sensitivity in combination with AS Bcl-2 was associated with down-regulation of Bcl-2 and pAkt, which was correlated with the induction of Bax and caspase-3, leading to apoptosis. AS Bcl-2 appeared to be superior to trastuzumab with respect to regulating the signal-transduction pathways involved in breast carcinoma cells. Cancer 2005.

Kojima, K, Fujita, Y, Nozawa, Y, Deguchi, T and Ito, M. MiR-34a attenuates paclitaxel-resistance of hormone-refractory prostate cancer PC3 cells through direct and indirect mechanisms. Prostate 70: 1501-1512

Article

Oct 2010
PROSTATE

Patients with hormone-refractory prostate cancer are treated with taxane drugs, but eventually become drug resistant. We aimed to elucidate the molecular mechanisms underlying paclitaxel resistance of hormone-refractory prostate cancer with a special focus on the roles of miR-34a and SIRT1. Paclitaxel-resistant cells (PC3PR) were generated from hormone-refractory PC3 cells. The expression levels of mRNA and miRNA were determined by reverse transcriptase PCR and those of protein were by Western blot analysis. Transfection of miRNA precursor or siRNA was performed using the liposome-mediated method. MiR-34a over-expression and SIRT1 knockdown attenuated paclitaxel resistance of PC3PR cells. MiR-34a expression was reduced in PC3PR cells compared with PC3 cells, while the expression levels of HuR and Bcl2 as well as SIRT1 were elevated in PC3PR cells. Luciferase reporter assays revealed that both SIRT1 3'-UTR and promoter activities were higher in PC3PR cells than in PC3 cells. Introduction of miR-34a precursor into PC3PR cells resulted in decreases in HuR, Bcl2, and SIRT1 expression and inhibition of the SIRT1 3'-UTR activity. HuR knockdown reduced SIRT1 and Bcl2 expression. These results suggest that miR-34a not only directly but also indirectly via regulating HuR expression acts on the 3'-UTR of SIRT1 and Bcl2 mRNAs, thereby controlling their expression. Thus, in PC3PR cells, reduced expression of miR-34a confers paclitaxel resistance via up-regulating SIRT1 and Bcl2 expression. MiR-34a and its downstream targets SIRT1 and Bcl2 play important roles in the development of paclitaxel resistance, all of which can be useful biomarkers and promising therapeutic targets for the drug resistance in hormone-refractory prostate cancer.

Altered DNA methylation is associated with docetaxel resistance in human breast cancer cells

Article

May 2010
INT J ONCOL

Docetaxel is an effective chemotherapy drug to treat breast cancer but the underlying molecular mechanisms of drug resistance are not fully understood. DNA methylation is an epigenetic event, involved in the control of gene expression, which is known to play an important role in cancer and chemotherapy drug resistance. To investigate the role of DNA methylation in docetaxel resistance in breast cancer we used two human breast cancer cell lines (MCF-7 and MDA-MB-231) that were made resistant to docetaxel. Docetaxel-resistant sub-lines were treated with different concentrations of decitabine. Global methylation and DNA methyltransferase (DNMT) activity was measured using an ELISA-based assay. Quantitative real-time PCR was used to study DNMT gene expression. Cell viability was studied by MTT assay. Global methylation was increased in MCF-7 but not significantly changed in MDA-MB-231 docetaxel-resistant cells. Decreased DNMT activity and decreased DNMT1 and DNMT3b mRNA expression was associated with docetaxel resistance in both cell lines. To investigate how the components of the DNA methylation machinery may contribute towards docetaxel resistance, decitabine (5-aza-2'-deoxycytidine), an inhibitor of DNA methylation, was used. Decitabine treatment decreased global methylation, DNMT activity and DNMT1, DNMT3a and DNMT3b mRNA expression in MDA-MB-231 docetaxel-resistant cells. In contrast, decitabine-treated MCF-7 docetaxel-resistant cells showed increased DNMT1, DNMT3a and DNMT3b mRNA expression indicating a cell line specific effect of decitabine. Decitabine treatment increased resistance in MCF-7 docetaxel-resistant cells and in the parental MCF-7 and MDA-MB231 docetaxel-sensitive cell lines, however, it did not alter response to docetaxel in MDA-MB-231 docetaxel-resistant cells. This study demonstrates that changes in the DNA methylation machinery are associated with resistance to docetaxel in breast cancer cells. The use of epigenetic therapies, as a strategy to overcome drug resistance, needs to be investigated more fully to determine their effectiveness in different cancers and for different chemotherapy drugs.

Estrogen Receptor α Controls a Gene Network in Luminal-Like Breast Cancer Cells Comprising Multiple Transcription Factors and MicroRNAs

Article

Mar 2010
Am J Pathol

Luminal-like breast tumor cells express estrogen receptor alpha (ERalpha), a member of the nuclear receptor family of ligand-activated transcription factors that controls their proliferation, survival, and functional status. To identify the molecular determinants of this hormone-responsive tumor phenotype, a comprehensive genome-wide analysis was performed in estrogen stimulated MCF-7 and ZR-75.1 cells by integrating time-course mRNA expression profiling with global mapping of genomic ERalpha binding sites by chromatin immunoprecipitation coupled to massively parallel sequencing, microRNA expression profiling, and in silico analysis of transcription units and receptor binding regions identified. All 1270 genes that were found to respond to 17beta-estradiol in both cell lines cluster in 33 highly concordant groups, each of which showed defined kinetics of RNA changes. This hormone-responsive gene set includes several direct targets of ERalpha and is organized in a gene regulation cascade, stemming from ligand-activated receptor and reaching a large number of downstream targets via AP-2gamma, B-cell activating transcription factor, E2F1 and 2, E74-like factor 3, GTF2IRD1, hairy and enhancer of split homologue-1, MYB, SMAD3, RARalpha, and RXRalpha transcription factors. MicroRNAs are also integral components of this gene regulation network because miR-107, miR-424, miR-570, miR-618, and miR-760 are regulated by 17beta-estradiol along with other microRNAs that can target a significant number of transcripts belonging to one or more estrogen-responsive gene clusters.

Involvement of miR-326 in chemotherapy resistance of breast cancer through modulating expression of multidrug resistance-associated protein 1

Article

Oct 2009

Multidrug resistance-associated protein (MRP-1/ABCC1) transports a wide range of therapeutic agents and may play a critical role in the development of multidrug resistance (MDR) in tumor cells. However, the regulation of MRP-1 remains controversial. To explore whether miRNAs are involved in the regulation of MRP-1 expression and modulate the sensitivity of tumor cells to chemotherapeutic agents, we analyzed miRNA expression levels in VP-16-resistant MDR cell line, MCF-7/VP, in comparison with its parent cell line, MCF-7, using a miRNA microarray. MCF-7/VP overexpressed MRP-1 mRNA and protein not MDR-1 and BCRP. miR-326 was downregulated in MCF-7/VP compared to MCF-7. Additionally, miR-326 was downregulated in a panel of advanced breast cancer tissues and consistent reversely with expression levels of MRP-1. Furthermore, the elevated levels of miR-326 in the mimics-transfected VP-16-resistant cell line, MCF-7/VP, downregulated MRP-1 expression and sensitized these cells to VP-16 and doxorubicin. These findings demonstrate for the first time the involvement of miRNAs in multidrug resistance mediated by MRP-1 and suggest that miR-326 may be an efficient agent for preventing and reversing MDR in tumor cells.

miR-34a, a microRNA up-regulated in a double transgenic mouse model of Alzheimer's disease, inhibits bcl2 translation

Article

Sep 2009

MicroRNAs (miRNAs) are short noncoding regulatory RNA molecules that modulate protein expression by inhibiting mRNA translation or promoting mRNA degradation. However, little is understood about the roles of miRNAs in Alzheimer's disease. During a research for miRNAs that are differentially expressed in cerebral cortex of APPswe/PSDeltaE9 mice (a model for Alzheimer's disease) and age-matched controls, one candidate miRNA that is relatively highly expressed, miR-34a, was studied further because sequence analysis suggested a likely interaction with the 3'-untranslated region of bcl2 mRNA. We show that the expression of miR-34a is inversely correlated with the protein level of bcl2 in APPswe/PSDeltaE9 mice and age-matched controls, and miR-34a expression directly inhibits bcl2 translation in SH-SY5Y cells. No effect on bcl2 mRNA level was observed. Western blot analysis of active caspase-3 showed higher levels in APPswe/PSDeltaE9 mice and stable transfecant cell line of miR-34a than in controls. Consistently, miR-34a knockdown through antisense LNA oligonucleotides increased the level of bcl2 protein in SH-SY5Y cells, which was accompanied by a decrease of active caspase-3. These findings suggested that bcl2 is an important functional target for miR-34a, and the abnormal expression of miR-34a may contribute to the pathogenesis of Alzheimer's disease, at least in part by affecting the expression of bcl2.

MiR-126 restoration down-regulate VEGF and inhibit the growth of lung cancer cell lines in vitro and in vivo

Article

Mar 2009

Vascular endothelial growth factor (VEGF) is a positive regulator of angiogenesis, and its expression is up-regulated in many carcinomas. In the present study, we found that a microRNA miR-126 has a binding site in 3'-untranslated region of the VEGF-A mRNA. In eight lung cancer cell lines, expression of miR-126 was down-regulated. Reporter gene assay showed that the co-transfection of mir-126 expression vector with pLuc-VEGF/mir126BS could reduce the activity of luciferase. Transfection experiments showed that miR-126 could decrease the expression of VEGF-A. Three human lung carcinoma cell lines A549, Y-90 and SPC-A1 were investigated as cancer models in vitro, and A549 infected by lentivirus-miR-126 (LV-miR-126) was studied in tumor xenograft model. Infection of LV-miR-126 can down-regulate the expression of VEGF-A in A549, Y-90 and SPC-A1 cell lines and can inhibit the growth of these cells. In addition, flow cytometry analysis revealed that LV-miR-126 infection can induce cell cycle G1 arrest in A549, Y-90 and SPC-A1 cells. Furthermore, in nude mice, the average weight of A549 tumor nodules in experimental group was reduced from 0.8035+/-0.1521 to 0.6235+/-0.0757g, with the inhibitive rate being 22.4%. All these results revealed that miR-126 may have a tumor suppressor function in lung cancer cells and could be a promising treatment in anticancer therapy.

Effects of miR-34a on cell growth and chemoresistance in prostate cancer PC3 cells

Article

Oct 2008
BIOCHEM BIOPH RES CO

Tumor suppressor p53 transcriptionally regulates expression of microRNA-34a, which confers translational inhibition and mRNA degradation of genes involved in cell cycle control and apoptosis. In various cancers, miR-34a expression is lost or reduced. Here, we investigated the role of miR-34a in prostate cancer cell lines. MiR-34a expression was markedly reduced in p53-null PC3 cells and p53-mutated DU145 cells compared with LNCaP cells expressing wild-type p53. In PC3 cell, ectopic expression of miR-34a decreased the SIRT1 mRNA and protein levels as well as protein levels of known direct target genes. Reporter assays revealed that miR-34a-induced SIRT1 inhibition occurred at the transcriptional but not post-transcriptional level despite the presence of a potential miR-34a binding site within its 3'-UTR. Ectopic miR-34a expression resulted in cell cycle arrest and growth inhibition and attenuated chemoresistance to anticancer drug camptothecin by inducing apoptosis, suggesting a potential role of miR-34a for the treatment of p53-defective prostate cancer.

Oncogenic aberrations of p16INK4/CDKN2 and cyclin D1 cooperate to deregulate G1 control

Article

Dec 1995

The p16INK4/CDKN2, D-type cyclins, their partner cyclin-dependent kinases, and retinoblastoma protein constitute a G1 regulatory pathway commonly targeted in oncogenesis. We show that, unexpectedly, abnormalities of p16INK4/CDKN2 occur concomitantly in two-thirds of cancer cell lines harboring aberrations of cyclin D1. Gene and protein transfer experiments demonstrated that concurrent alterations of cyclin D1 and p16 levels cooperate to (de)regulate G1 control in diploid fibroblasts, and that both events influence growth of retinoblastoma (RB)-positive, but not RB-deficient cancer cells. These results show that biological consequences of deregulating individual components along the pathway are unequal, reflecting their hierarchical roles in the G1 checkpoint control. Whereas RB defects eliminate the checkpoint completely, aberrations of the upstream components, such as cyclin D1 and p16INK4/CDKN2, can cooperate in multistep tumorigenesis.

Resnitzky D, Reed SI.. Different roles for cyclins D1 and E in regulation of the G1-to-S transition. Mol Cell Biol 15: 3463-3469

Article

Aug 1995

Ectopic expression of cyclins D1 and E was previously shown to accelerate the G1/S-phase transition, indicating that both classes of G1 cyclin control an event(s) that is rate limiting for entry into S phase. In order to determine whether cyclins D1 and E control the same or two different rate-limiting events, we have created cell lines that express both cyclins in an inducible manner. We show here that ectopic expression of both cyclins E and D1 in the same cell has an additive effect on shortening of the G1 interval relative to expression of any single cyclin. In order to further explore the molecular basis for G1 cyclin action, we used cell lines capable of expressing cyclin D1, E, or both prematurely and measured the effect of cyclin expression in early G1 on phosphorylation of the retinoblastoma susceptibility gene product (pRb). We show here that while premature expression of either cyclin alone advances the G1/S-phase transition to the same extent, premature expression of cyclin D1 leads to immediate appearance of hyperphosphorylated pRb, while premature expression of cyclin E does not. Ectopic expression of both cyclins E and D1 in the same cell has an additive effect on shortening of the G1 interval, while the effect on pRb phosphorylation is similar to the effect of cyclin D1 alone. These results suggest that cyclins E and D1 control two different events, both rate limiting for the G1/S-phase transition, and that pRb phosphorylation might be the rate-limiting event controlled by cyclin D1.

Cyclin D1 protein oscillates and is essential for cell cycle progression in human cell lines

Article

Apr 1994
ONCOGENE

Among the key cell cycle regulators, cyclin D1 has been implicated most strongly in oncogenesis. This G1 cyclin is a putative proto-oncogene whose clonal rearrangement and/or amplification and mRNA overexpression occurs in several types of human neoplasias. We have now raised a series of monoclonal antibodies to human cyclin D1 and analysed its regulation at the protein level in 40 human tumour cell lines. We found that 12 cell lines displayed low or undetectable cyclin D1 protein level, while the remaining lines accumulated the protein to a level comparable to, or moderately higher than, that of four normal diploid non-immortalized cell types. The cell cycle-dependent oscillation and subcellular localization of cyclin D1 were similar in both tumour and normal cells. The protein localized to the nucleus of G1 cells, and it was reduced to immunocytochemically undetectable level in DNA-replicating cells. At the functional level, microinjection and electroporation of anti-D1 antibodies revealed that in most tumour cell lines studied, including those with amplification at the cyclin D1 locus, this cyclin is essential for cell cycle progression in G1. Some tumours, however, seem to have evolved mechanism(s) that enable them to bypass the requirement for functional cyclin D1.

Acceleration of G1/S phase transition by expression of cyclin D1 and E with an inducible system

Article

Apr 1994

Conditional overexpression of human cyclins B1, D1, and E was accomplished by using a synthetic cDNA expression system based on the Escherichia coli tetracycline repressor. After induction of these cyclins in asynchronous Rat-1 fibroblasts, a decrease in the length of the G1 interval was observed for cyclins D1 and E, consistent with an acceleration of the G1/S phase transition. We observed, in addition, a compensatory lengthening of S phase and G2 so that the mean cell cycle length in populations constitutively expressing these cyclins was unchanged relative to those of their uninduced counterparts. We found that expression of cyclin B1 had no effect on cell cycle dynamics, despite elevated levels of cyclin B-associated histone H1 kinase activity. Induction of cyclins D1 and E also accelerated entry into S phase for synchronized cultures emerging from quiescence. However, whereas cyclin E exerted a greater effect than cyclin D1 in asynchronous cycling cells, cyclin D1 conferred a greater effect upon stimulation from quiescence, suggesting a specific role for cyclin D1 in the G0-to-G1 transition. Overexpression of cyclins did not prevent cells from entering into quiescence upon serum starvation, although a slight delay in attainment of quiescence was observed for cells expressing either cyclin D1 or cyclin E. These results suggest that cyclins D1 and E are rate-limiting activators of the G1-to-S phase transition and that cyclin D1 might play a specialized role in facilitating emergence from quiescence.

Huang Y, Ray S, Reed JC, Ibrado AM, Tang C, Nawabi A & Bhalla K.Estrogen increases intracellular p26Bcl-2 to p21Bax ratios and inhibits taxol-induced apoptosis of human breast cancer MCF-7 cells. Breast Cancer Res Treat 42: 73−81

Article

Feb 1997

Recent studies have demonstrated that following estrogen ablation, estrogen responsive breast cancer cells undergo apoptosis. In addition, estrogen receptor (ER) expression has been strongly correlated with the expression of the bcl-2 gene product, p26Bcl-2 protein, which is known to inhibit apoptosis. In the present studies, we investigated whether estrogen affects the intracellular levels of p26Bcl-2 and thereby modulates taxol-induced apoptosis of estrogen responsive human breast cancer MCF-7 cells. Transfer of MCF-7 cells to a culture-medium without estrogens reduced their intracellular p26Bcl-2 levels by 50%. Inclusion of 0.1 microM estradiol in the medium produced approximately a four-fold increase in p26Bcl-2, but not p29Bcl-x1, or p21Bax levels; the expression of the c-myc and mdr-1 genes remained unchanged. Estradiol-induced four-fold increase in the ratio of the p26Bcl-2 to p21Bax levels caused a significant decline in the lethal, kilobase size DNA fragments of apoptosis, which had resulted when MCF-7 cells were cultured in a medium without estrogen. In addition, in MCF-7 cells, estradiol-induced increase in the intracellular p26Bcl-2 to p21Bax ratios was associated with a significant reduction in the large-sized DNA fragmentation induced by treatment with taxol. The increased ratios also protected MCF-7 cells against taxol-mediated cytotoxicity as assessed by the MTT assay. These results suggest that by modulating p26Bcl-2 levels, estrogens may affect the antitumor activity of taxol and potentially of other anti-breast cancer drugs against estrogen responsive human breast cancer cells.

Elledge RM, Green S, Howes L, Clark GM, Berardo M, Allred DC, Pugh R, Ciocca D, Ravdin P, O'Sullivan J, Rivkin S, Martino S, Osborne CKbcl-2, p53, and response to tamoxifen in estrogen receptor-positive metastatic breast cancer: a Southwest Oncology Group study. J Clin Oncol 15: 1916-1922

Article

Jun 1997

To test the hypothesis that high bcl-2 expression and accumulation of p53 protein, both of which should inhibit apoptosis, are associated with a poorer tamoxifen response and a more aggressive clinical course in estrogen receptor (ER)-positive metastatic breast cancer. A total of 205 paraffin-embedded tumor blocks were evaluated for nuclear p53 (a marker of p53 inactivation) and cytoplasmic bcl-2 by immunohistochemistry (IHC). All patients received tamoxifen as initial therapy for metastatic disease. The study began in 1982 and follow-up duration of the 24 patients last known alive is 8 years. Response to tamoxifen and time to treatment failure (TTF) were not significantly associated with p53 status, although patients with higher p53 had a worse survival (P = .008; median, 36 v 20 months). Higher bcl-2 expression was associated with higher levels of ER (P = .02), better response to tamoxifen (62% v 49%; P = .07), longer TTF (median, 9 v 5 months; P = .002), and better survival (median, 40 months v 25 months; P = .009). In multivariate analyses, including ER, progesterone receptor (PgR), and p53, high bcl-2 remained significantly associated with a longer TTF (P = .007) and survival (P = .07). p53 status was a significant factor for shorter survival (P = .05), but not for TTF (P = .61). p53 status, as determined by IHC is not significantly associated with response to tamoxifen, although tumors with altered p53 protein are inherently more aggressive. Contrary to expectation, high bcl-2 identifies a relatively indolent phenotype of ER-positive metastatic breast cancer, in which patients experience a better clinical response to tamoxifen and a longer survival.

Expression of Bcl-2 in human breast cancer: Correlation between hormone receptor status, p53 protein accumulation and DNA strand breaks associated with apoptosis

Article

Dec 1997

The expression of Bcl-2, a suppressor of apoptotic cell death, was investigated in 52 invasive carcinomas of the breast using reverse transcription-polymerase chain reaction and immunohistochemical methods. After consideration of both sets of results, 42 tumors (80.8%) were confirmed to be positive (Bcl-2(+)) and 10 (19.2%) were judged negative (Bcl-2(-)) for Bcl-2 expression. Related factors (p53 protein accumulation, hormone receptor status and apoptotic cell index) were also examined using immunohistochemical and in situ end-labeling methods to elucidate their correlations with Bcl-2 expression. Bcl-2 expression correlated significantly with the hormone receptor status, whereas it showed significant inverse correlations with p53 accumulation and the apoptotic index. It was concluded that estrogen and mutant p53 are related to the regulation of Bcl-2 expression and that the ability to prevent tumor cell death due to Bcl-2 can be developed by breast cancers.

Neoadjuvant Chemotherapy in Breast Cancer: Significantly Enhanced Response With Docetaxel

Article

Apr 2002

To compare the efficacy of neoadjuvant (NA) docetaxel (DOC) with anthracycline-based therapy and determine the efficacy of NA DOC in patients with breast cancer initially failing to respond to anthracycline-based NA chemotherapy (CT). Patients with large or locally advanced breast cancer received four pulses of cyclophosphamide 1,000 mg/m(2), doxorubicin 50 mg/m(2), vincristine 1.5 mg/m(2), and prednisolone 40 mg (4 x CVAP) for 5 days. Clinical tumor response was assessed. Those who responded (complete response [CR] or partial response [PR]) were randomized to receive further 4 x CVAP or 4 x DOC (100 mg/m(2)). All nonresponders received 4 x DOC. One hundred sixty-two patients were enrolled; 145 patients completed eight cycles of NA CT. One hundred two patients (66%) achieved a clinical response (PR or CR) after 4 x CVAP. After randomization, 50 patients received 4 x CVAP and 47 patients received 4 x DOC. In patients who received eight cycles of CT, the clinical CR (cCR) and clinical PR (cPR) (94% v 66%) and pathologic CR (pCR) (34% v 16%) response rates were higher (P =.001 and P =.04) in those who received further DOC. Intention-to-treat analysis demonstrated cCR and cPR (85% v 64%; P =.03) and pCR (31% v 15%; P =.06). Axillary lymph node examination revealed residual tumor in 33% of patients who received 8 x CVAP and 38% of patients who received further DOC. In patients who failed to respond to the initial CVAP, 4 x DOC resulted in a cCR and cPR rate of 55% and a pCR rate of 2%. Forty-four percent of these patients had residual tumor within axillary lymph nodes. NA DOC resulted in substantial improvement in responses to DOC.

Roles of cyclin D1 and related genes in growth inhibition, senescence and apoptosis

Article

Jul 1999

It is now apparent that apoptosis is closely linked to the control of cell cycle progression. During the G1 to S progression, cyclin D1, p53, and the cyclin dependent kinase inhibitors p21WAF1 and p27kip1 can play roles in induction of apoptosis. During the G2 and M phases, premature activation of Cdk1 can cause cells to enter mitotic catastrophe, which results in apoptosis. In this review we focus on factors acting during G1 and S, particularly cyclin D1, and their effects on cell growth, senescence and apoptosis. We emphasize that cyclin D1 can have diverse effects on cells depending on its level of expression, the specific cell type, the cell context and other factors. Possible mechanisms by which cyclin D1 exerts these diverse effects, via cyclin dependent kinase-dependent and -independent pathways, are discussed.

Potential Predictive Value of Bcl-2 for Response to Tamoxifen in the Adjuvant Setting of Node-Positive Breast Cancer

Article

Jan 2005

Approximately 50% of patients with estrogen receptor (ER)-positive breast cancer (BC) and 70%-80% of patients with ER-positive and progesterone receptor (PgR)-positive BC respond to hormonal therapy. Additional predictive markers are needed. A group of 287 patients with ER- and/or PgR-positive tumors was selected from 804 patients previously enrolled in a multicenter phase III trial. Bcl-2 expression was evaluated and correlated with response to adjuvant tamoxifen and survival. Estrogen receptor and PgR were determined by biochemical means and Bcl-2 by immunohistochemistry. With a median follow-up of 76 months (95 relapses and 60 deaths), of the 287 patients with, 187 (65%) had Bcl-2-positive tumors and 78 of these patients received tamoxifen. Of the 100 patients with Bcl-2-negative disease, 51 received tamoxifen and 49 regular follow-up. Using patients treated with tamoxifen as a reference, a univariate analysis of disease-free interval for patients who did not receive tamoxifen showed a hazard ratio (HR) of 1.42 (95% CI, 0.82-2.44; P = 0.21) for patients with Bcl-2-positive disease and a HR of 1.05 (95% CI, 0.55-1.99; P = 0.89) for patients with Bcl-2-negative disease (P = 0.48). After adjusting for number of positive lymph nodes, degree of receptor and PgR positivity, and type of surgery, the HRs were 1.54 (95% CI, 0.87-2.73; P = 0.14) for Bcl-2-positive disease and 1.05 (95% CI, 0.52-2.11; P = 0.88) for Bcl-2-negative disease. Despite its being a retrospective nonrandomized study with a relatively low number of patients, our results suggest that Bcl-2 deserves further evaluation as a predictive factor of sensitivity to tamoxifen.

The facts and doubts about beginning of the human life and personality

Article

Mar 2004

“What a piece of work is a man!” William Shakespeare, Hamlet“To those of average curiosity about the wonders of nature, it is likely that two great mysteries have stirred the imagination; and each concerns a birth. Who has not gazed into the heavens on the starlit night and wondered about the birth of the universe? And who has not been stimulated by the sight of the newly born baby to the marvel at the unseen events within the mother’s uterus that have led to the birth of such a perfect creation?”(1) These words written by the Professor Sir Graham (Mont) Liggins open Pandora’s box of questions, dilemmas, doubts and controversies about human life and its beginning offering everybody lifelong challenge to solve mystery of life.Entering this filed scientists have been remiss in failing to translate science into the terms that allow mankind to share their excitement of discovering life before birth. Regardless to remarkable scientific development, curiosity, and speculations dating back to Hippocrates, life before birth still remains a big secret. Different kinds of intellectuals involved themselves trying to contribute to the solution of human life puzzle. They are led by the idea that each newborn child will only reach its full potential if its development in uterus is free from any adverse influence, providing the best possible environment for the embryo/foetus. Considering embryo/foetus, it should be always kept in mind amazing aspect of these parts of human life in which the mother and the embryo/foetus, although locked in the most intimate relationships, are at ALL TIMES two separate people. Accepting embryo/foetus as the person opened new set of questions about its personality and human rights. Today, synthesis between scientific data and hypotheses, philosophical thought, and issues in the humanities, has become pressing necessity in order to deal with ethical, juridical and social problems arising from man’s interference in many aspects and stages of life. (2)

Miyoshi Y, Taguchi T, Kim SJ, Tamaki Y, Noguchi SPrediction of response to docetaxel by immunohistochemical analysis of CYP3A4 expression in human breast cancers. Breast Cancer 12(1): 11-15

Article

Feb 2005

Docetaxel (DOC) is inactivated by CYP3A4, high expression of which in tumor tissue might serve as a resistance mechanism. In the present study, the CYP3A4 protein level in breast cancers was determined by immunohistochemistry, and its relationship with the response to DOC treatment was studied. Thirty-one patients with locally advanced (n = 21) or recurrent (n = 10) breast cancers underwent tumor biopsy, followed by DOC treatment (60 mg/m2 q3w). Expression of CYP3A4 was studied by immunohistochemistry. Patients with CYP3A4 negative tumors (n = 15) by immunohistochemistry showed a significantly (P < 0.01) higher response rate (67%) to DOC treatment than those with CYP3A4 positive tumors (n = 16, 19%). The positive predictive value, negative predictive value, and diagnostic accuracy of CYP3A4 expression by immunohistochemistry in the prediction of response to DOC were 67%, 81%, and 74%, respectively. Immunohistochemical analysis of CYP3A4 expression in tumor cells might be clinically useful in the prediction of tumor response to DOC.

Alterations of β-tubulin isotypes in breast cancer cells resistant to docetaxel

Article

Sep 2005
FASEB J

Docetaxel is one of the most active drugs used to treat breast cancer. The cellular target of docetaxel is the microtubule, specifically the beta-tubulin subunit, that comprises a series of isotypes and that can modulate function. This study has examined the role of alteration in beta-tubulin isotypes in vitro and has sequenced the beta-tubulin gene to determine if there were mutations, both of which may represent important mechanisms of acquired resistance to docetaxel. Breast cancer cells, MCF-7 (oestrogen-receptor positive) and MDA-MB-231, (oestrogen-receptor negative) were made resistant to docetaxel in vitro. Expression of beta-tubulin isotypes (class I, II, III, IVa, IVb, and VI) was determined at the RNA and protein level using RT-PCR and western analysis, respectively. DNA sequencing evaluated the beta-tubulin gene. At the mRNA level, class I, II, III, and IVa beta-tubulin mRNA isotypes were over-expressed in docetaxel-resistant MCF-7 cells when compared with the docetaxel-sensitive parental cells. However, class VI beta-tubulin mRNA isotype expression was decreased in resistant cells. In MDA-MB-231 cells, there was a decrease in expression of the class I and class IVa beta-tubulin mRNA. However, there were increased expressions in class II, IVb, and VI beta-tubulin mRNA isotypes in resistant cells. Western analysis has confirmed corresponding increases in beta-tubulin protein levels in MCF-7 cells. However, in MDA-MB-231 cells, there were decreased protein levels for class II and class III beta-tubulin. This study demonstrates that altered expression of mRNA beta-tubulin isotypes and modulation of beta-tubulin protein levels are associated with acquired docetaxel resistance in breast cancer cells. This allows further understanding and elucidation of mechanisms involved in resistance to docetaxel.

Miska, EA. How microRNAs control cell division, differentiation and death. Curr Opin Genet Dev 15: 563-568

Article

Nov 2005
CURR OPIN GENET DEV

Eric Alexander Miska

After the milestone discovery of the first microRNA in 1993, the past five years have seen a phenomenal surge of interest in these short, regulatory RNAs. Given that 2% of all known human genes encode microRNAs, one main goal is to uncover microRNA function. Although it has been more difficult to assign function to microRNAs in animals than it has been in plants, important roles are emerging: in invertebrates, microRNAs control developmental timing, neuronal differentiation, tissue growth and programmed cell death. Functional studies in zebrafish and mice point toward important roles for microRNAs during morphogenesis and organogenesis. Finally, microRNAs might regulate viral infection and human cancer.

Randomized Phase III Study of Docetaxel Compared With Paclitaxel in Metastatic Breast Cancer

Article

Aug 2005

This randomized, controlled, multicenter, open-label, phase III study compared docetaxel versus paclitaxel in patients with advanced breast cancer that had progressed after an anthracycline-containing chemotherapy regimen. Patients (n = 449) were randomly assigned to receive either docetaxel 100 mg/m2 (n = 225) or paclitaxel 175 mg/m2 (n = 224) on day 1, every 21 days until tumor progression, unacceptable toxicity, or withdrawal of consent. In the intent-to-treat population, both the median overall survival (OS, 15.4 v 12.7 months; hazard ratio [HR], 1.41; 95% CI, 1.15 to 1.73; P = .03) and the median time to progression (TTP, 5.7 months v 3.6 months; HR, 1.64; 95% CI, 1.33 to 2.02; P < .0001) for docetaxel were significantly longer than for paclitaxel, and the overall response rate (ORR, 32% v 25%; P = .10) was higher for docetaxel. These results were confirmed by multivariate analyses. The incidence of treatment-related hematologic and nonhematologic toxicities was greater for docetaxel than for paclitaxel; however, quality-of-life scores were not statistically different between treatment groups over time. Docetaxel was superior to paclitaxel in terms of OS and TTP. ORR was higher for docetaxel. Hematologic and nonhematologic toxicities occurred more frequently in the docetaxel group. The global quality-of-life scores were similar for both agents over time.

Nakamoto M, Jin P, O’Donnell WT, Warren STPhysiological identification of human transcripts translationally regulated by a specific microRNA. Hum Mol Genet 14: 3813-3821

Article

Jan 2006

One mechanism by which endogenous microRNAs (miRNAs) function is to suppress translation of target mRNAs. Computational identification of target mRNAs is hampered by the partial complementarity between miRNAs and their targets and the lack of in vivo approaches to identify targets. Here, we identify mRNAs that are regulated by specific endogenous miRNA by detecting shifts in individual mRNA abundance in polyribosome profiles following miRNA knockdown via siRNA. We have identified human genes whose mRNAs were found at significantly increased levels in the heavy polyribosome fractions following miRNA miR-30a-3p knockdown. If antibody was available, targets showed an increase in protein levels following the miRNA knockdown and a decrease following the miRNA overexpression. Although all identified transcripts have sequences that partially complement miR-30a-3p, none was identified by commonly used computational means. These data suggest that the functional interaction between miRNAs and mRNA targets is more complex than previously realized and describe an approach to refine predictive algorithms.

Modulation of multidrug resistance efflux pump activity to overcome chemoresistance in cancer

Article

Sep 2006
CURR OPIN PHARMACOL

Early publications using cultured cancer cells immediately recognized the phenomenon of resistance to anticancer agents. However, it was not until 1973 that it was first demonstrated that a major factor in the resistance of cancer cells was that of reduced drug accumulation. This year marks the 30th anniversary of the discovery by Juliano and Ling that P-glycoprotein mediates this active efflux of chemotherapeutic drugs from cancer cells. Since this seminal finding, the investigation of P-glycoprotein (MDR1, ATP binding cassette [ABC]B1) has proceeded with great vigour. However, it soon became apparent that P-glycoprotein was not expressed in all drug-resistant cells that displayed an accumulation deficiency, which led to the discovery of other ABC transporters involved in drug efflux. In 1992, the multidrug resistance-associated protein (MRP1, ABCC1) was identified in small cell lung cancer followed by breast cancer resistance protein (mitoxantrone resistance protein, ABCG2) in 1999. After three decades of research, can we confidently define the contribution of multidrug resistance transporters to chemoresistance and do we have clinically useful drugs to sensitise cancers?

Predictive factors for response to docetaxel in human breast cancers

Article

Oct 2006

Shinzaburo Noguchi

Docetaxel has come into wide use recently for the treatment of breast cancer in neoadjuvant, adjuvant and metastatic settings. Docetaxel binds to beta-tubulin and causes kinetic abnormalities in the dynamics of microtubules by increasing their polymerization and inhibiting their depolymerization, resulting in elevated levels of microtubule formation. During metaphase, defective spindle formation induced by docetaxel activates the mitotic checkpoint and leads to cell cycle arrest, culminating in apoptosis. However, docetaxel is not effective for all breast cancers. For example, in metastatic settings, the response rate to docetaxel reportedly ranges from 30 to 50%. It is therefore very important to develop a diagnostic method with high accuracy for the prediction of sensitivity to docetaxel in order to avoid unnecessary treatment. Currently it is impossible to identify, before the initiation of therapy, the patients for whom docetaxel will be effective. Various biological parameters have been studied clinically for their ability to predict response to docetaxel, such as parameters related to: (1) efflux (p-glycoprotein) and metabolism (CYP3A4); (2) beta-tubulin (somatic mutation of beta-tubulin and changes in beta-tubulin isotypes levels); (3) cell cycle (HER2, BRCA1 and Aurora-A); and (4) apoptosis (p53, BCL2 and thioredoxin). More recently, gene expression profiling techniques have been used for the development of a prediction model for response to docetaxel. In the present paper, clinical studies that have been conducted recently to identify predictive factors for response to docetaxel are reviewed together with a presentation of our recent work in this field.

Histone deacetylase inhibitor, trichostatin A, increases the chemosensitivity of anticancer drugs in gastric cancer cell lines

Article

Oct 2006

Epigenetic alterations of the histone acetylation play an important role in the regulation of gene expression associated with cell cycles and apoptosis that may affect the chemosensitivity of gastric carcinomas. Recently, a histone deacetylase inhibitor, trichostatin A (TSA), was proven to be a chemo-sensitizer on human erythroleukemia cells. With the aim of improving the chemotherapeutic efficacy of gastric carcinoma, the effect of TSA on the chemosensitivity of several anticancer drugs in gastric carcinoma cells was investigated. Human gastric cancer cell lines, OCUM-8 and MKN-74, and 5 anticancer drugs, 5-fluorouracil (5-FU), paclitaxel (PTX), oxaliplatin (OXA), irinotecan (SN38) and gemcitabine (GEM) were used. In both gastric cancer cell lines, a synergistic anti-proliferative effect by the combination of TSA (30 ng/ml) with 5-FU, PTX or SN38 showed a synergistic anti-proliferative effect in OCUM-8 and MKN-74 cells. TSA increases the expression of p21, p53, DAPK-1 and the DAPK-2 gene in both OCUM-8 and MKN-74 cells. In conclusion, TSA is a promising chemotherapeutical agent in combination with anticancer drugs of 5-FU, PTX and SN38 in gastric cancer cell lines. The up-regulation of p53, p21, DAPK-1 and DAPK-2 might be associated with the synergistic effect of TSA.

Kent OA, Mendell JT.. A small piece in the cancer puzzle: microRNAs as tumor suppressors and oncogenes. Oncogene 25: 6188-6196. Review

Article

Nov 2006
ONCOGENE

The known classes of genes that function as tumor suppressors and oncogenes have recently been expanded to include the microRNA (miRNA) family of regulatory molecules. miRNAs negatively regulate the stability and translation of target messenger RNAs (mRNA) and have been implicated in diverse processes such as cellular differentiation, cell-cycle control and apoptosis. Examination of tumor-specific miRNA expression profiles has revealed widespread dysregulation of these molecules in diverse cancers. Although studies addressing their role in cancer pathogenesis are at an early stage, it is apparent that loss- or gain-of-function of specific miRNAs contributes to cellular transformation and tumorigenesis. The available evidence clearly demonstrates that these molecules are intertwined with cellular pathways regulated by classical oncogenes and tumor suppressors such as MYC, RAS and p53. Incorporation of miRNA regulation into current models of molecular cancer pathogenesis will be essential to achieve a complete understanding of this group of diseases.

Kastl L, Brown I, Schofield ACmiRNA-34a is associated with docetaxel resistance in human breast cancer cells. Breast Cancer Res Treat 131: 445-454

Abstract

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