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Sizing up miRNAs as cancer genes
Abstract
Findings over the last year or so have built the case that microRNAs might contribute to cancer. Three studies now definitively show this to be the case and also suggest that these small RNAs could be used to categorize tumors.
... In cancers, including thyroid cancers, aberrant miRNA expression is commonly presumed to contribute to alterations in mRNA repression, which may promote pathogenesis [23] [24] [25] [26]. That is, miRNA and target RNA expression are presumed to be negatively correlated. ...
... Total RNA and small RNA quality control was by Fragment Analyzer (Agilent version# 1.1.0.11). qPCR was performed with 2 µL RNA input from each fraction, or from pooled fractions HMW-RISC (15)(16), MMW-RISC (17)(18)(19)(20)(21)(22)(23)(24)(25)(26), LMW-RISC (27)(28)(29)(30)(31)(32)(33)(34)(35), and RISC-Poor (36-47) using TaqMan microRNA Reverse transcription kit (ABI 4366597 Lot#00636931), TaqMan miRNA stem-loop RT primers/qPCR primer probe sets (ABI 4427975) (cel-miR-39 ID# 000200 Lot#P180110-003B10, miR-16 ID# 000391 Lot#P171018-000H05, U6 ID# 001937 Lot#P170729-001405), TaqMan Universal Master Mix II, no UNG (ABI 4440040 Lot#1802074), as described in manufacturer's protocol, on a CFX96 Real-time System (Bio-Rad). For each RNA fraction, miR-16 and U6 were normalized to cel-miR-39, then to fraction 14 using the 2 -ΔΔCT method. ...
Thyroid cancer is the most prevalent malignancy of the endocrine system. We and others have shown that several microRNAs, which are post-transcriptional gene regulators, are aberrantly expressed in anaplastic thyroid cancer (ATC) and papillary thyroid cancer (PTC) tissues, as well as cell lines derived from these cancers. In the cell, miRNAs are bound to Argonaute (AGO) proteins as what could be termed low molecular weight RNA-Induced Silencing Complexes (LMW-RISCs) that can then assemble with additional proteins, mRNA, and translation machinery into high molecular weight RISCs (HMW-RISCs) that also exert regulatory function. In this study, we sought to analyze the association of miRNAs with RISC complexes in ATC and PTC. For ATC and PTC lines, miRNA species were enriched in both HMW-RISC and LMW-RISC cellular fractions, compared with intermediate molecular weight fractions and very low molecular weight (AGO-poor) fractions. Furthermore, 60% of all miRNAs were slightly more abundant in LMW-RISC versus HMW-RISC fractions by ~2-4 fold. Surprisingly, miR-21-5p, one of the most abundant miRNAs in both ATC and PTC lines and one of the most widely studied oncogenic miRNAs in many solid tumors, was consistently one the least abundant miRNAs in HMW-RISC and the most enriched miRNA in LMW-RISC fractions. These findings may suggest that miR-21 has a role or roles distinct from canonical posttranscriptional regulation in cancer. Furthermore, the methodology described here is a useful way to assess the distribution of miR-21 between HMW and LMW-RISCs and may help to reveal the true roles of this miRNA in thyroid cancer development, progression, and treatment.
... There is an equal distribution between both sexes (1.06:1 -f: m) with a mean age of 60 years at presentation [3]. 5-year-survival rates vary considerably between 37.5% (pancreatic NEN) and 88.3% (rectal NEN) depending on location, tumor stage and patients age [2,4,5]. GEP-NEN are most frequently encountered in the ileum (35.5%), followed by tumors in the rectum and appendix (20% and 17.8%, respectively). ...
... Several miRs act as either oncogenes (so-called "onco-miRs") or tumor suppressors thereby influencing the growth and dissemination of tumors [11,12]. Multiple studies demonstrated that miR-expression profiles could potentially be used as diagnostic and prognostic markers and probably be even an important diagnostic factor in determination of the primary site cases in CUP [4,5,13,14]. ...
The incidence of neuroendocrine neoplasias (NEN) continues to increase. Since the primary tumor cannot be diagnosed in some cases of metastatic disease, new biomarkers are clearly needed to find the most probable site of origin. Tissue samples from 79 patients were analyzed and microRNA profiles were generated from a total of 76 primary tumors, 31 lymph node and 14 solid organ metastases. NEN metastases were associated with elevated levels of miR-30a-5p, miR-210, miR-339-3p, miR-345 and miR-660. Three microRNAs showed a strong correlation between proliferation index and metastatic disease in general (miR-150, miR-21 and miR-660). Further, each anatomic location (primary or metastatic) had one or more site-specific microRNAs more highly expressed in these tissues. Comparison between primary tumors and metastases revealed an overlap only in pancreatic (miR-127) and ileal tumors (let-7g, miR-200a and miR-331). This thorough analysis of gastroenteropancreatic neuroendocrine tumors demonstrates site-specific microRNA profiles, correlation with proliferation indices as well as corresponding nodal and distant metastases. Using microRNA profiling might improve NEN diagnostics by linking metastases to a most probable site of origin.
... Different studies highlighted miRNAs involvement in human tumors, including NSCLCs [6], and implicated their roles as oncogenes [7] or tumor suppressors [2,8] through post-transcriptional modulation of gene expression. Several molecular and epigenetic mechanisms are involved in miRNAs deregulation in cancer, mostly because miRNAs are often localized at fragile sites [9], cancer susceptibility loci [9] or in proximity of CpG islands [10]. Despite numerous studies on miRNA deregulation in lung cancer, a consensus on which miRNAs are crucial for lung carcinogenesis and progression has remained elusive. ...
... Different studies highlighted miRNAs involvement in human tumors, including NSCLCs [6], and implicated their roles as oncogenes [7] or tumor suppressors [2,8] through post-transcriptional modulation of gene expression. Several molecular and epigenetic mechanisms are involved in miRNAs deregulation in cancer, mostly because miRNAs are often localized at fragile sites [9], cancer susceptibility loci [9] or in proximity of CpG islands [10]. Despite numerous studies on miRNA deregulation in lung cancer, a consensus on which miRNAs are crucial for lung carcinogenesis and progression has remained elusive. ...
Lung cancer is the leading cause of tumor-related death worldwide and more efforts are needed to elucidate lung carcinogenesis. Here we investigated the expression of 641 miRNAs in lung tumorigenesis in a K-Ras(+/LSLG12Vgeo);RERTn(ert/ert) mouse model and 113 human tumors. The conserved miRNA cluster on chromosome 12qF1 was significantly and progressively upregulated during murine lung carcinogenesis. In particular, miR-494-3p expression was correlated with lung cancer progression in mice and with worse survival in lung cancer patients. Mechanistically ectopic expression of miR-494-3p in A549 lung cancer cells boosted the tumor-initiating population enhanced cancer cell motility, and increased the expression of stem cell-related genes. Importantly, miR-494-3p improved the ability of A549 cells to grow and metastasize in vivo, modulating NOTCH1 and PTEN/PI3K/AKT signaling.
Overall, these data identify miR-494-3p as a key factor in lung cancer onset and progression and possible therapeutic target.
... MicroRNAs, also known as miRNAs, are non-proteincoding transcripts that consists of 19-24 nucleotides, which inhibit the translation of target messenger RNAs (mRNAs) to control post-transcriptional modulation of gene expression. 13 MiRNAs have been the subject of much exploration as potential causes of inflammatory and malignant disorders. 14 Multiple miRNAs have been linked to controlling CAC development, for example miR-214, miR-146a and miR-21. ...
Despite being the subject of multiple cancer studies, nothing is known about miR-597-5p’s role in colitis-associated colorectal cancer (CAC). We intend to explore how miR-597-5p influences the growth and development of CAC. In order to construct a CAC model, mice were stimulated with azoxymethane (AOM)/dextran sulfate sodium (DSS). The in situ hybridization (ISH) and quantitative real-time polymerase chain reaction (qRT-PCR) was used for the detection of miR-597-5p expression. The protein expression of CXCL5 was determined by western blotting, immunohistochemistry and enzyme-linked immuno sorbent assay (ELISA). The histologic colitis score and hematoxylin and eosin (HE) staining were used to evaluate degree of damage to colonic tissues. The proportion of macrophages detected in colon tumors was also measured using flow cytometry. The transwell test was employed to assess macrophage migration. It was found that the miR-597-5p and its target CXCL5 had a negative correlation. MiR-597-5p expression was decreased, while CXCL5 expression was raised in CAC tissues. In AOM/DSS-induced mice, miR-597-5p deficiency in intestinal epithelial cells resulted in decreasing colon length as well as increasing tumor numbers and histologic colitis score, which was reversed by CXCL5 inhibition. MiR-597-5p deficiency facilitated macrophage recruitment in AOM/DSS-induced mice and promoted macrophage migration in vitro, which were reversed by CXCL5 inhibition. Deficiency of miR-597-5p aggravated macrophage recruitment and tumorigenesis in a mouse CAC model, suggesting that miR-597-5p agonists may have an anti-inflammatory therapeutic effect in inflammatory bowel diseases and reduce the risk of developing CAC.
... Genome-wide studies revealed that miRNA genes are frequently located at chromosomal breakpoints, genomic regions associated with cancer, and at minimal regions of loss of heterozygosity/gains. These events show their role in human tumorigenesis [44,45]. Several global studies have shown that disruption of mature miRNA biogenesis in cells leads to their cancerous development Profiling miRNAs at different stages of cancer can provide insight into miRNA deregulation. ...
Pancreatic cancer (PC) is one of the deadliest cancers worldwide. MicroRNAs (miRs) are sensitive molecular diagnostic tools that can serve as highly accurate biomarkers in many disease states in general and cancer specifically. MiR-based electrochemical biosensors can be easily and inexpensively manufactured, making them suitable for clinical use and mass production for point-of-care use. This paper reviews nanomaterial-enhanced miR-based electrochemical biosensors in pancreatic cancer detection, analyzing both labeled and label-free approaches, as well as enzyme-based and enzyme-free methods.
... In 2002, Calin et al. first demonstrated that miR-15 and miIR-16 are frequently deleted or down-regulated in chronic lymphocytic leukemia [120]. Subsequently, aberrant miRNA expression, and amplification or deletion of miRNAs are observed in various human tumors [121,122]. MiRNAs are differentially expressed in cancer cells, in which they form distinct and unique miRNA expression patterns [123]. These properties make miRNAs become potential biomarkers for cancer diagnosis, in particular for the early detection of cancer [124]. ...
... Soon after the discovery of microRNAs-miRNAs [57]-it was recognized that they can be components of both oncogene and anti-oncogene pathways [58]. For example, it was proven that the p53 transcription factor regulates expression of several microRNAs of the miR-34 family, which consists of three microRNAs: miR-34a, miR-34b, and miR-34c [59]. ...
Herein, I present an updated and contextualized literature review of functional genomic studies of natural phenols in the context of cancer. I suggest multilevel chemopreventive and anticancer mechanisms of action, which are shared by multiple dietary natural phenols. Specifically, I cite evidence that curcumin and resveratrol have multilevel anti-cancer effects through: (1) inducing either p53-dependent or p53-independent apoptosis in cancer cell lines, (2) acting as potent regulators of expression of oncogenic and anti-oncogenic microRNAs, and (3) inducing complex epigenetic changes that can switch off oncogenes/switch on anti-oncogenes. There is no simple reductionist explanation for anti-cancer effects of curcumin and resveratrol. More generally, multilevel models of chemoprevention are suggested for related natural phenols and flavonoids such as genistein, quercetin, or luteolin.
... Together, we 483 conclude that the indirect negative feedback via miRNAs can potentially generate 484 phenotypic diversity compared to direct negative feedback. cancer progression [1,12,15,21,44,48,51,52,54,78,92]. In order to investigate the effects 489 of a miRNA-mediated single-negative-feedback loop (SNFL), we here built a stochastic 490 framework describing the competitive titration between miRNAs and their target altogether. ...
Micro-RNAs (miRNAs) are small non-coding RNAs that regulate gene expression post-transcriptionally in eukaryotes by binding with target mRNAs and preventing translation. miRNA-mediated feedback motifs are ubiquitous in various genetic networks which control cellular decision-making. A key question is how such a feedback mechanism may affect gene expression noise. To answer this, we have developed a mathematical model to study the effects of a miRNA-dependent negative feedback loop on mean expression and noise in target mRNAs. Combining analytics and simulations, we show the existence of an expression threshold demarcating repressed and expressed regimes in agreement with earlier studies. The steady-state mRNA distributions are bimodal near the threshold, where copy numbers of mRNAs and miRNAs exhibit enhanced anticorrelated fluctuations. Moreover, variation of negative-feedback strength shifts the threshold locations and modulates the noise profiles. Notably, the miRNA-mRNA binding affinity and feedback strength collectively shape the bimodality. We also compare our model with a direct auto-repression motif, where a gene produces its own repressor. Auto-repression fails to produce bimodal mRNA distributions as found in miRNA-based indirect repression, suggesting the crucial role of miRNAs in creating phenotypic diversity. Together, we demonstrate how miRNA-dependent negative feedback modifies the expression threshold and leads to a broader parameter regime of bimodality compared to the no-feedback case.
... miRs, as biomarkers, may fulfil this request after we have successfully understood how to employ them in the correct manner. Aberrant miR signatures are commonly observed in NSCLC and they are most frequently associated to upregulation rather than downregulation [111][112][113][114][115][116][117][118][119][120][121]123]. These abnormally overexpressed miRs represent a valuable repertoire from which the proper panel of biomarkers can be selected for association to "alarm-miR-21" in the design of non-invasive tests for next-generation NSCLC detection. ...
TABLE OF CONTENTS 1. Abstract 2. Introduction 3. miRs and cancer 4. miR-21 the par excellence onco-miR 5. miR signatures as potential biomarkers 6. miRs as therapeutic targets 7. miRs as future therapies in pulmonary diseases 8. Ethics approval and consent to participate 9. Acknowledgment 10. Funding 11. Conflict of interest 12. References 1. Abstract Since the discovery of the first microRNA (miR), almost three decades ago, the roles played by miRs under normal and diseased settings have been widely investigated. miRs are found to play crucial roles in cancer initiation and progression, as well as towards therapy response mechanisms. Therefore, they are relevant and attractive targets for therapeutic development. Many preclinical studies have demonstrated their promise as future anti-cancer tools. Recently, increasing number of early phase clinical trials have emerged. In this Commentary, we will summarize the major discoveries within the miR research field and highlight the status quo of current miR-therapeutics, which has prominent potential of impacting future cancer regimens given their massive dysregulation in oncogenic processes.
... Recent genome analysis revealed several biomarkers which are related to RNA, DNA, exosome, et cetera. A class of endogenous non-coding RNAs is MicroRNAs (miRNAs) (nearly 22 nt) which module the expression of the gene after transcription through degradation or translation blockage of target mRNAs (Bartel, 2004;Caldas and Brenton, 2005). It is well-known that cancer cells may release miRNAs via exosomes to enhance proliferation and migration (Li, 2018;Yoshimura, 2018;Zeng, 2018). ...
Aim: This study aimed to accurately identification of potential miRNAs for gastric cancer (GC) diagnosis at the early stages of the disease.
Methods: We used GSE106817 data with 2,566 miRNAs to train the machine learning models. We used the Boruta machine learning variable selection approach to identify the strong miRNAs associated with GC in the training sample. We then validated the prediction models in the independent sample GSE113486 data. Finally, an ontological analysis was done on identified miRNAs to eliciting the relevant relationships.
Results: Of those 2,874 patients in the training the model, there were 115 (4%) patients with GC. Boruta identified 30 miRNAs as potential biomarkers for GC diagnosis and hsa-miR-1343-3p was at the highest ranking. All of the machine learning algorithms showed that using hsa-miR-1343-3p as a biomarker, GC can be predicted with very high precision (AUC; 100%, sensitivity; 100%, specificity; 100% ROC; 100%, Kappa; 100) using with the cut-off point of 8.2 for hsa-miR-1343-3p. Also, ontological analysis of 30 identified miRNAs approved their strong relationship with cancer associated genes and molecular events.
Conclusion: The hsa-miR-1343-3p could be introduced as a valuable target for studies on the GC diagnosis using reliable biomarkers.
... miRs, as biomarkers, may fulfil this request after we have successfully understood how to employ them in the correct manner. Aberrant miR signatures are commonly observed in NSCLC and they are most frequently associated to upregulation rather than downregulation [111][112][113][114][115][116][117][118][119][120][121]123]. These abnormally overexpressed miRs represent a valuable repertoire from which the proper panel of biomarkers can be selected for association to "alarm-miR-21" in the design of non-invasive tests for next-generation NSCLC detection. ...
Since the discovery of the first microRNA (miR), almost three decades ago, the roles played by miRs under normal and diseased settings have been widely investigated. miRs are found to play crucial roles in cancer initiation and progression, as well as towards therapy response mechanisms. Therefore, they are relevant and attractive targets for therapeutic development. Many preclinical studies have demonstrated their promise as future anti-cancer tools. Recently, increasing number of early phase clinical trials have emerged. In this Commentary, we will summarize the major discoveries within the miR research field and highlight the status quo of current miR-therapeutics, which has prominent potential of impacting future cancer regimens given their massive dysregulation in oncogenic processes.
... All rights reserved. 5 miRNAs are involved in many cellular processes in insects, including proliferation, differentiation, death, apoptosis, metabolism, and development (Brennecke et al., 2003;Chen et al., 2004;Poy et al., 2004;Caldas & Brenton, 2005;Schratt et al., 2006). In natural insect immune responses, miRNAs regulate translation of antimicrobial peptides as well as the production of protein kinase II and inhibitor of apoptosis (IAP) protein (Ishiguro et al., 2006;Garbuzov & Tatar, 2010;Guo et al., 2020). ...
MicroRNAs (miRNAs) are regulatory RNA molecules that bind to target messenger RNAs (mRNAs) and affect the stability or translational efficiency of the bound mRNAs. Single or dual-luciferase reporter systems have been successfully used to identify miRNA target genes in mammalian cells. These reporter systems, however, are not sensitive enough to verify miRNA-target gene relationships in insect cell lines because the promoters of the target luciferase (usually Renilla) used in these reporter systems are too weak to drive sufficient expression of the target luciferase in insect cells. In this study, we replaced the SV40 promoter in the psiCHECK-2 reporter vector, which is widely used with mammalian cell lines, with the HSV-TK or AC5.1 promoter to yield two new dual-luciferase reporter vectors, designated psiCHECK-2-TK and psiCHECK-2-AC5.1, respectively. Only psiCHECK-2 and psiCHECK-2-AC5.1 had suitable target (Renilla)/reference (firefly) luciferase activity ratios in mammalian (HeLa and HEK293) and insect (Sf9, S2, Helicoverpa zea fat body and ovary) cell lines, while psiCHECK-2-TK had suitable Renilla/firefly luciferase activity ratios regardless of the cell line. Moreover, psiCHECK-2-TK successfully detected the interaction between Helicoverpa armigera miRNA9a and its target, the 3′-untranslated region of heat shock protein 90, in both mammalian and H. zea cell lines, but psiCHECK-2 failed to do so in H. zea cell lines. Furthermore, psiCHECK-2-TK with the target sequence, HzMasc (H. zea Masculinizer), accurately differentiated between H. zea cell lines with or without the negative regulation factor (miRNA or piRNA) of HzMasc. These data demonstrate that psiCHECK-2-TK can be used to functionally characterize small RNA target genes in both mammalian and insect cells.
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... miRNAs are known to target and modulate the expression of important protein components of these biological processes [19,44,45]. In addition, numerous miRNAs are dysregulated during carcinogenesis as previously discussed [46,47]. Thus, it is clear that miRNAs promote genomic and chromosomal instability contributing to tumorigenesis. ...
Genomic instability consists of a range of genetic alterations within the genome that contributes to tumor heterogeneity and drug resistance. It is a well-established characteristic of most cancer cells. Genome instability induction results from defects in DNA damage surveillance mechanisms, mitotic checkpoints and DNA repair machinery. Accumulation of genetic alterations ultimately sets cells towards malignant transformation. Recent studies suggest that miRNAs are key players in mediating genome instability. miRNAs are a class of small RNAs expressed in most somatic tissues and are part of the epigenome. Importantly, in many cancers, miRNA expression is dysregulated. Consequently, this review examines the role of miRNA dysregulation as a causal step for induction of genome instability and subsequent carcinogenesis. We focus specifically on mechanistic studies assessing miRNA(s) and specific subtypes of genome instability or known modes of genome instability. In addition, we provide insight on the existing knowledge gaps within the field and possible ways to address them.
... Mature microRNAs (miRNAs) are formed by splicing of precursors encoded by endogenous genes, and many studies have shown that although miRNAs are not directly involved in translation, they have important biological roles such as in the formation of silencing complexes (8,9). As gene regulators, miRNAs induce mRNA degradation or inhibit translation (10,11). ...
Osteosarcoma is a highly malignant tumor that occurs in the bone. Previous studies have shown that multiple microRNAs (miRNAs) regulate the development of osteosarcoma. This study aimed to explore the role of miR-629-5p and its target gene, caveolin 1 (CAV1), in osteosarcoma development. To analyze the expression of miR-629-5p and CAV1 mRNA in osteosarcoma tissues and cell lines, qRT-PCR analysis was performed. Dual-luciferase reporter experiments were subsequently performed to validate the relationship between CAV1 and miR-629-5p. CCK8 assay was used to measure osteosarcoma cell proliferation, and wound-healing assay was performed to study their migratory phenotype. Our findings revealed that miR-629-5p was overexpressed in osteosarcoma tissues and cells, and thereby enhanced cell proliferation and migration. Further, we validated that miR-629-5p targets CAV1 mRNA directly. CAV1 expression, which was negatively correlated with miR-629-5p expression, was found to be downregulated in osteosarcoma tissue samples. Moreover, our data showed that an increase in CAV1 level led to a decline in osteosarcoma cell proliferation and migration, which could be rescued by miR-629-5p upregulation. Overall, our study confirmed that miR-629-5p promoted osteosarcoma proliferation and migration by directly inhibiting CAV1.
... MicroRNAs (miRNAs) are small non-coding regulatory RNAs (17-25 nucleotides) that to bind complementary sequences in the 3-untranslated regions (3-UTR) of various target mRNAs to promote degradation or translational repression (Caldas and Brenton, 2005). miRNAs play a role in almost all aspects of cancer biology, such as proliferation, apoptosis, invasion/metastasis, and angiogenesis (Lee and Dutta, 2009). ...
Gastric cancer (GC) is one of the leading causes of cancer-associated deaths worldwide. Due to the lack of typical symptoms and effective biomarkers for non-invasive screening, most patients develop advanced-stage GC by the time of diagnosis. Circulating microRNA (miRNA)-based panels have been reported as a promising tool for the screening of certain types of cancers. In this study, we performed differential expression analysis of miRNA profiles of plasma samples obtained from gastric cancer and non-cancer patients using two independent Gene Expression Omnibus (GEO) datasets: GSE113486 and GSE124158. We identified three miRNAs, hsa-miR-320a, hsa-miR-1260b, and hsa-miR-6515-5p, to distinguish gastric cancer cases from non-cancer controls. The three miRNAs showed an area under the curve (AUC) over 0.95 with high specificity (>93.0%) and sensitivity (>85.0%) in both the discovery datasets. In addition, we further validated these three miRNAs in two external datasets: GSE106817 [sensitivity: hsa-miR-320a (99.1%), hsa-miR-1260b (97.4%), and hsa-miR-6515-5p (92.2%); specificity: hsa-miR-320a (88.8%), hsa-miR-1260b (89.6%), and hsa-miR-6515-5p (88.7%); and AUC: hsa-miR-320a (96.3%), hsa-miR-1260b (97.4%), and hsa-miR-6515-5p (94.6%)] and GSE112264 [sensitivity: hsa-miR-320a (100.0%), hsa-miR-1260b (98.0%), and hsa-miR-6515.5p (98.0%); specificity: hsa-miR-320a (100.0%), hsa-miR-1260b (100.0%), and hsa-miR-6515.5p (92.7%); and AUC: hsa-miR-320a (1.000), hsa-miR-1260b (1.000), and hsa-miR-6515-5p (0.988)]. On the basis of these findings, the three miRNAs can be used as potential biomarkers for gastric cancer screening, which can provide patients with a higher chance of curative resection and longer survival.
... One is that if the expression of miRNA is up-regulated, there is a good chance that the expression of tumor suppressor genes is downregulated, which may facilitate tumorigenesis. The other is that if the expression of miRNA is down-regulated, there is a good chance that the expression of corresponding oncogenes is upregulated, which may also cause the development of tumors 142 . Therefore, the development of therapies against CSC-based miRNAs mainly involves two aspects: restoring the expression of tumor suppressor miRNAs through miRNA analogs and inhibiting the expression of oncogenic miRNAs by miRNA antagonists or inhibitors 143 . ...
Cancer stem cells (CSCs) are a subpopulation of cancer cells with functions similar to those of normal stem cells. Although few in number, they are capable of self-renewal, unlimited proliferation, and multi-directional differentiation potential. In addition, CSCs have the ability to escape immune surveillance. Thus, they play an important role in the occurrence and development of tumors, and they are closely related to tumor invasion, metastasis, drug resistance, and recurrence after treatment. Therefore, specific targeting of CSCs may improve the efficiency of cancer therapy. A series of corresponding promising therapeutic strategies based on CSC targeting, such as the targeting of CSC niche, CSC signaling pathways, and CSC mitochondria, are currently under development. Given the rapid progression in this field and nanotechnology, drug delivery systems (DDSs) for CSC targeting are increasingly being developed. In this review, we summarize the advances in CSC-targeted DDSs. Furthermore, we highlight the latest developmental trends through the main line of CSC occurrence and development process; some considerations about the rationale, advantages, and limitations of different DDSs for CSC-targeted therapies were discussed.
... hsa-miR-199b-5p is highly expressed in tumor tissues from patients with pancreatic cancer. Dysregulation of miRNA expression associated with cell cycle causing transition of normal cells into cancer cells are frequent phenomena 29,30 . The present study reveals that the upregulated miRNAs in MG conditions are predominantly expressed in the events of cell cycle, cell proliferation, and angiogenesis. ...
Adaptation of humans in low gravity conditions is a matter of utmost importance when efforts are on to a gigantic leap in human space expeditions for tourism and formation of space colonies. In this connection, cardiovascular adaptation in low gravity is a critical component of human space exploration. Deep high-throughput sequencing approach allowed us to analyze the miRNA and mRNA expression profiles in human umbilical cord vein endothelial cells (HUVEC), cultured under gravity (G), and stimulated microgravity (MG) achieved with a clinostat. The present study identified totally 1870 miRNAs differentially expressed in HUVEC under MG condition when compared to the cells subjected to unitary G conditions. The functional association of identified miRNAs targeting specific mRNAs revealed that miRNAs, hsa-mir-496, hsa-mir-151a, hsa-miR-296-3p, hsa-mir-148a, hsa-miR-365b-5p, hsa-miR-3687, hsa-mir-454, hsa-miR-155-5p, and hsa-miR-145-5p differentially regulated the genes involved in cell adhesion, angiogenesis, cell cycle, JAK-STAT signaling, MAPK signaling, nitric oxide signaling, VEGF signaling, and wound healing pathways. Further, the q-PCR based experimental studies of upregulated and downregulated miRNA and mRNAs demonstrate that the above reported miRNAs influence the cell proliferation and vascular functions of the HUVEC in MG conditions effectively. Consensus on the interactome results indicates restricted fluctuations in the transcriptome of the HUVEC exposed to short-term MG that could lead to higher levels of endothelial functions like angiogenesis and vascular patterning.
... MicroRNAs (miRNAs) are deemed as a unique class of conserved small noncoding RNAs that are consisted of about 19-25 nucleotides [7]. A growing body of evidence has indicated that miRNAs function as crucial mediators in regulating the expression levels of genes via binding to complementary sequences in the 3'-untranslated regions (3'-UTR) of their target mRNAs [8]. ...
As one of the most prevalent malignant tumors, pancreatic cancer (PC) is a leading fatal cancer worldwide. Surging evidence has unraveled that miRNAs are involved in the occurrence and progression of multiple cancers, including PC. The tumor suppressor effects of miR-4269 have been certified in gastric carcinoma. However, the potential function of miR-4269 remains largely unclear, which drives us to identify the role of miR-4269 in PC development. In this study, we determined the expression pattern of miR-4269 in PC cells and normal cells. Results of RT-qPCR analysis illuminated that miR-4269 expression level in PC cells was lower than that in normal cells. Functional assays demonstrated that upregulation of miR-4269 obviously inhibited the proliferation, migration and invasion of PC cells. In order to elucidate the mechanism governing miR-4269 in PC, we carried out bioinformatics analysis and further experimental investigations. Our results validated that ZEB1 was a direct target of miR-4269. Additionally, ZEB1 activated the transcription of OXT1. More importantly, miR-4269 attenuated the expression level of OXT1 via targeting ZEB1. Ultimately, our findings confirmed that miR-4269 served as a cancer suppressor in PC through regulation of ZEB1/OTX1 pathway, which suggested that miR-4269 might represent a promising target for the clinical treatment of PC.
... Disruption in the microRNA expression has shown agreement with specific pathological forms and treatment response in various tumors. Recently, microRNAs or AMOs (anti-microRNA antisense oligodeoxyribonucleotide) have been used alone or together with drugs, chemotherapies, and radiotherapy [89]. MicroRNAs are more stable than mRNAs. ...
... They modulate gene and protein expression by directly binding to the 3′ untranslated region (3′ UTR) of target mRNA and promoting RNA degradation and/or inhibiting mRNA translation. miRNAs are deregulated in a wide array of human cancers, where they can act as oncogenes or tumor suppressors by inhibiting tumor suppressor or oncogene mRNA expression, respectively [3][4][5][6][7][8][9][10][11]. ...
Background and purpose
microRNAs are small noncoding RNAs that play important roles in cancer regulation. In this study, we investigated the expression, functional effects and mechanisms of action of microRNA-29a (miR-29a) in glioblastoma (GBM).
Methods
miR-29a expression levels in GBM cells, stem cells (GSCs) and human tumors as well as normal astrocytes and normal brain were measured by quantitative PCR. miR-29a targets were uncovered by target prediction algorithms, and verified by immunoblotting and 3′ UTR reporter assays. The effects of miR-29a on cell proliferation, death, migration and invasion were assessed with cell counting, Annexin V-PE/7AAD flow cytometry, scratch assay and transwell assay, respectively. Orthotopic xenografts were used to determine the effects of miR-29a on tumor growth.
Results
Mir-29a was downregulated in human GBM specimens, GSCs and GBM cell lines. Exogenous expression of miR-29a inhibited GSC and GBM cell growth and induced apoptosis. miR-29a also inhibited GBM cell migration and invasion. PDGFC and PDGFA were uncovered and validated as direct targets of miR-29a in GBM. miR-29a downregulated PDGFC and PDGFA expressions at the transcriptional and translational levels. PDGFC and PDGFA expressions in GBM tumors, GSCs, and GBM established cell lines were higher than in normal brain and human astrocytes. Mir-29a expression inhibited orthotopic GBM xenograft growth.
Conclusions
miR-29a is a tumor suppressor miRNA in GBM, where it inhibits cancer stem cells and tumor growth by regulating the PDGF pathway.
... However, subsequent direct experimental testing of noncoding region SNPs has shown they can have significant functional effects on gene expression by disrupting transcriptional regulatory sites (Kasowski et al., 2010;Maurano et al., 2012) or altering the binding of other recently discovered regulatory factors such as micro-RNAs (miRNAs) (Saunders et al., 2007). miRNAs are short 18-to 24-nucleotide RNA molecules that play an important role in regulating many biologic pathways including pathways involved in cancer progression (Caldas and Brenton, 2005;Calin and Croce, 2006;Ceppi and Peter, 2014;Kent and Mendell, 2006;Kong et al., 2012;Lujambio and Lowe, 2012). They exert their regulatory control by binding via complete or partial complementarity with sequences in the 3 0 UTR of a target mRNA. ...
Germline single nucleotide polymorphisms are one of the most common genetic variations. Polymorphisms that cause nonsynonymous mutations in gene coding regions are known to cause serious deleterious downstream effects. However, even polymorphisms in noncoding regions can have profound functional consequences by disrupting essential regulatory sites. Specifically, polymorphisms that alter microRNA binding sites can disrupt the regulation of hallmark biological pathways implicated in tumorigenesis and tumor progression. Many of these microRNA-associated polymorphisms (miR-SNPs) have recently been shown to be important biomarkers of cancer risk, prognosis, and treatment outcomes. This review will summarize the functional impact of key miR-SNPs and define a subset of miR-SNPs that may be clinically useful prognostic or predictive biomarkers. © 2018 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.
... MicroRNAs (miRNAs) are short, non-coding RNAs (-22 nucleotides) that binds to the 3'-untranslated region (3'-UTR) of mRNAs and modulate gene expression by controlling mRNA translation or degradation [7,8]. Aberrant expression of miRNAs can cause a range of human disorders, especially malignant diseases. ...
Background/aims:
Treatment options for metastatic castrate-resistant prostate cancer (mCRPC) are limited and typically centered on paclitaxel-based chemotherapy. In this study, we aimed to evaluate whether miR-34a attenuates chemoresistance to paclitaxel by regulating target genes associated with drug resistance.
Methods:
We used data from The Cancer Genome Atlas to compare miR-34a expression levels in prostate cancer (PC) tissues with normal prostate tissues. The effects of miR-34a inhibition and overexpression on PC proliferation were evaluated in vitro via Cell Counting Kit-8 (CCK-8) proliferation, colony formation, apoptosis, and cell-cycle assays. A luciferase reporter assay was employed to identify the interactions between miR-34a and specific target genes. To determine the effects of up-regulation of miR-34a on tumor growth and chemo-resistance in vivo, we injected PC cells overexpressing miR-34a into nude mice subcutaneously and evaluated the rate of tumor growth during paclitaxel treatment. We examined changes in the expression levels of miR-34a target genes JAG1 and Notch1 and their downstream genes via miR-34a transfection by quantitative reverse transcription PCR (qRT-PCR) and western blot assay.
Results:
miR-34a served as an independent predictor of reduced patient survival. MiR-34a was down-regulated in PC-3PR cells compared with PC-3 cells. The CCK-8 assay showed that miR-34a overexpression resulted in increased sensitivity to paclitaxel while miR-34a down-regulation resulted in chemoresistance to paclitaxel in vitro. A study of gain and loss in a series of functional assays revealed that PC cells expressing miR-34a were chemosensitive. Furthermore, the overexpression of miR-34a increased the sensitivity of PC-3PR cells to chemotherapy in vivo. The luciferase reporter assay confirmed that JAG1 and Notch1 were directly targeted by miR-34a. Interestingly, western blot analysis and qRT-PCR confirmed that miR-34a inhibited the Notch1 signaling pathway. We found that miR-34a increased the chemosensitivity of PC-3PR cells by directly repressing the TCF1/ LEF1 axis.
Conclusion:
Our results showed that miR-34a is involved in the development of chemosensitivity to paclitaxel. By regulating the JAG1/Notch1 axis, miR-34a or its target genes JAG1 or Notch1 might serve as potential predictive biomarkers of response to paclitaxel-based chemotherapy and/or therapeutic targets that will help to overcome chemoresistance at the mCRPC stage.
... miRNAs, a class of approximately 22-nucleotide ncRNAs, repress the expression of their target genes by translational arrest or by cleaving RNA transcripts via binding to the 3′-UTR of target mRNAs. Recently, miRNA-mediated regulations have been verified to play a pivotal role in tumor development (Caldas and Brenton 2005;Hwang and Mendell 2007;Lee and Dutta 2006). LncRNAs are transcripts of more than 200 nt in length without an apparent protein-coding capacity. ...
Recently, accumulating evidence has demonstrated that non-coding RNAs (ncRNAs) play a vital role in oncogenicity. Nevertheless, the regulatory mechanisms and functions remain poorly understood, especially for lncRNAs and circRNAs. In this study, we simultaneously detected, for the first time, the expression profiles of the whole transcriptome, including miRNA, circRNA and lncRNA + mRNA, in five pairs of laryngeal squamous cell carcinoma (LSCC) and matched non-carcinoma tissues by microarrays. Five miRNAs, four circRNAs, three lncRNAs and five mRNAs that were dysregulated were selected to confirm the verification of the microarray data by quantitative real-time PCR (qRT-PCR) in 20 pairs of LSCC samples. We constructed LSCC-related competing endogenous RNA (ceRNA) networks of lncRNAs and circRNAs (circRNA or lncRNA–miRNA–mRNA) respectively. Functional annotation revealed the lncRNA-mediated ceRNA network were enriched for genes involved in the tumor-associated pathways. Hsa_circ_0033988 with the highest degree in the circRNA-mediated ceRNA network was associated with fatty acid degradation, which was responsible for the depletion of fat in tumor-associated cachexia. Finally, to clarify the ncRNA co-regulation mechanism, we constructed a circRNA–lncRNA co-regulated network by integrating the above two networks and identified 9 modules for further study. A subnetwork of module 2 with the most dysregulated microRNAs was extracted to establish the ncRNA-involved TGF-β-associated pathway. In conclusion, our findings provide a high-throughput microarray data of the coding and non-coding RNAs and establish the foundation for further functional research on the ceRNA regulatory mechanism of non-coding RNAs in LSCC.
... MicroRNAs (miRNAs) are small non-coding RNAs post-transcriptionally repress the translation or promote the degradation of targeted mRNAs [3]. Generally, one single miRNA involves in the regulation of multiple target genes via binding to their 3'-untranslated region (3′UTR) [4]. ...
MiR-629-5p has been shown to function as a tumor promoter in some types of cancer. However, the role of miR-629-5p in colorectal cancer remains unclear. Here, the significant upregulation of miR-629-5p in colorectal cancer tissues and cell lines were observed. Overexpression of miR-629-5p showed a positive effect on cell proliferation and migration. The enhanced miR-629-5p level also suppressed cell apoptosis and resulted in a low Bax level and a high Bcl-2 level. Further downregulating miR-629-5p demonstrated opposite effects. CXXC finger protein 4 (CXXC4) was predicted as a direct target of miR-629-5p. Dual-luciferase reporter and western blotting assays exhibited miR-629-5p directly binded to the 3'UTR of CXXC4 and then downregulated its expression at post-transcriptional level. CXXC4 knockdown rescued the decreased cell proliferation and migration and the enhanced cell apoptosis induced by inhibiting miR-629-5p expression. Notably, overexpression of miR-629-5p also conferred 5-fluorouracil sensitivity, which was partly abrogated by coexpression of CXXC4. Overall, the results presented here suggest that miR-629-5p functions as a tumor promoter by improving proliferation and migration and repressing apoptosis and 5-FU sensitivity in colorectal cancer progression by directly downregulating CXXC4.
... MicroRNA (miRNA) is a short, non-coding RNA (approximately 22 nucleotides in length) that binds to the 3′-untranslated region (3′-UTR) of mRNA and regulates gene expression by controlling mRNA translation or degradation [6,7]. MiRNAs are involved in various biological processes. ...
Background/aims:
Chemoresistance is largely responsible for relapses of bladder cancer during clinical therapy. However, the molecular mechanisms involved in the chemoresistance of bladder cancer are unclear. Growing evidence supports the theory that microRNAs (miRNAs) play an important role in chemotherapeutic drug resistance because they are downregulated in many malignancies that have been implicated in the regulation of diverse processes in cancer cells. More specifically, the extent and precise mechanism of the involvement of miR-34as in chemoresistance to epirubicin (EPI) in the treatment of bladder cancer remains unclear.
Methods:
In this study, real-time quantitative polymerase chain reaction (PCR) was used to analyze the expression of miR-34a in bladder cancer cell line BIU87 and its EPI chemoresistant cell line BIU87/ADR. The miR-34a profiles in bladder cancer tissues were obtained from The Cancer Genome Atlas database. The effect of miR-34a on chemosensitivity was evaluated by cell viability assays, colony formation assays, and in vivo experimentation. Apoptosis and the cell cycle were examined by flow cytometry. A luciferase reporter assay was used to assess the target genes of miR-34a. Western blot and qPCR were used to analyze the expression of target proteins and downstream molecules.
Results:
The downregulation of miR-34a in bladder cancer serves as an independent predictor of reduced patient survival. The CCK-8 assay showed that miR-34a overexpression resulted in increased sensitivity to EPI, while miR-34a downregulation resulted in chemoresistance to EPI in vitro. Moreover, it was found that miR-34a increased the sensitivity of BIU87/ADR cells to chemotherapy in vivo. The luciferase reporter assay ascertained that TCF1 and LEF1 are direct target genes of miR-34a. It was found that miR-34a increased chemosensitivity in BIU87/ADR cells by inhibiting the TCF1/LEF1 axis.
Conclusions:
The results of this study indicate that miR-34a contributes to the chemosensitivity of BIU87/ADR by inhibiting the TCF1/LEF1 axis. Consequently, miR-34a is a determinant of BIU87 chemosensitivity and may therefore serve as a potential therapeutic target in bladder cancer treatment.
... MicroRNAs are a uniquely stable set of ubiquitously expressed small noncoding RNAs that belong to a class of small non-coding RNAs approximately 19-25 nucleotides in length and are able to bind complementary sequences in the 3′-untranslated regions (3′-UTR) of various target mRNAs to promote degradation or translational repression. 2,3 In cancer, miRNAs modulate stemness, EMT, expression of tumorsuppressor genes and oncogenes, and many other essential pathways that phenotypically affect cancer cells, such as drug resistance, tumor growth, invasion, and metastasis. [4][5][6][7][8] In the present study, we found that expression of miR-629 was upregulated in pancreatic cancer tissues and cell lines. ...
The FOXO signaling pathway has been reported to have an important role in human cancer. Expression of miR-629 was markedly upregulated in pancreatic cancer and negatively correlated with FOXO3. Therefore, exploring the regulatory mechanism of miR-629 and FOXO3 signaling may provide valuable clinical targets for pancreatic cancer therapy. In the current study, we found that overexpressing and inhibiting miR-629, respectively, enhanced and reduced the cell proliferation and metastasis of pancreatic cancer cells in vitro and in vivo compared with parental cells or cells transfected with a control vector. Furthermore, we found that miR-629 negatively regulated FOXO3 protein expression and decreased the activity of a luciferase reporter construct containing the FOXO3 3′-untranslated region. These results show that miR-629 regulates FOXO3 at the posttranscriptional level, resulting in enhanced cell proliferation and invasion of pancreatic carcinoma. Furthermore, we found that overexpressing miR-629 enhanced, while inhibiting miR-629 reduced, the stem cell-like phenotype of pancreatic cancer cells in vitro. A functional polymorphism at miR-629-binding site in the 3′-UTR of FOXO3 gene confers a decreased risk of progression in pancreatic carcinoma. Furthermore, these findings suggest that miR-629 has a vital role in promoting the development of pancreatic cancer and may represent a novel prognostic biomarker and therapeutic target.
... By binding the 3'-untranslated region (3'-UTR) of mRNA, miRNA suppresses protein synthesis through mRNA degradation or translational repression. As a result, miRNAs may act as either tumor suppressors or oncogenes (11)(12)(13). It is becoming increasingly evident that miRNAs serve important roles in cancer etiology. ...
MicroRNAs (miRNAs) have been demonstrated to serve an important role in diverse biological processes and cancer progression. Downregulation of microRNA-497 (miR-497) has been observed in human colorectal cancer (CRC) tissues, but the function of miR-497 in CRC has not been well investigated. In the present study, it was demonstrated that expression of miR-497 was significantly downregulated in human CRC tissues compared to adjacent normal tissues. Enforced expression of miR-497 inhibited proliferation, migration and invasion abilities of CRC cell lines SW1116 and SW480. Furthermore, overexpres- sion of miR-497 inhibited phosphoinositide 3-kinase/AKT and mitogen-activated protein kinase/extracellular signal-regulated kinase signaling by targeting insulin receptor substrate 1 (IRS1). In human clinical specimens, IRS1 was inversely correlated with miR-497 in CRC tissues. Collectively, the results of the present study demonstrate that miR-497 is a tumor suppressor miRNA and indicate its potential application for the treatment of human CRC in the future.
... Abnormal expression of miRNAs is significantly associated with multiple human diseases, including obesity, cardiovascular diseases and cancer (9,13). Previous studies have also demonstrated that downregulation or upregulation of miRNAs is associated with multiple types of human cancer, where they function as tumor suppressors or oncogenes depending on the function of their target genes (14)(15)(16). Notably, miRNAs have been reported to be involved in the carcinogenesis and development of OS, and may be prognostic markers or therapeutic targets for patients with OS (17)(18)(19). Therefore, miRNAs may be promising targets for OS treatment. ...
Osteosarcoma (OS) is the most common malignant bone tumor in children and adolescents. microRNAs (miRNAs) have previously been reported to be involved in the carcinogenesis and progression of OS, and may be useful prognostic markers or therapeutic targets for patients with OS. miRNA‑130a has been previously studied in multiple types of human cancer. However, its expression and function in OS has not been well documented. The aim of the present study was to investigate the expression, biological functions and molecular mechanisms underlying the effect of miR‑130a in OS. miR‑130a was significantly downregulated in OS tissues and cell lines compared with normal bone tissue and a normal osteoblast cell line. miR‑130a expression levels was significantly negatively correlated with the clinical stage and metastasis of OS. Further studies indicated that overexpression of miR‑130a inhibited OS cell proliferation, migration and invasion in vivo. In terms of the mechanisms underlying this effect, zinc finger E‑box binding homeobox 1 (ZEB1) was demonstrated to act as a direct target of miR‑130a in OS. Furthermore, downregulation of ZEB1 by interference with small interfering RNA mimicked the effects of transfection with an miR‑130a mimic in OS. In conclusion, these results demonstrated that miR‑130a functioned as a tumor suppressor in OS, partially via targeting ZEB1, suggesting that miR‑130a may be considered as a target for the treatment of patients with OS.
... The epiphany was established by Calin and colleagues with the discovery that two miRNAs, miR-15 and miR-16, are deleted or downregulated in the majority of B cell chronic lymphocytic leukemia cases, followed by a report that 50 % of all known miRNAs (at that time) were located in cancer-associated regions or fragile sites 281, 282 . Alterations in miRNA expression patterns are now considered a common feature of tumors as both up-and downregulation of miRNAs has been frequently described for distinct tumor entities [283][284][285][286] . Besides the location in cancerassociated chromosomal regions, aberrant miRNA expression can be the result of several additional mechanisms, including perturbation of transcription, repression of the global miRNA processing machinery and mutations in miRNA genes or in the recognition elements in their target mRNAs 287,288 . ...
... By targeting multiple transcripts, a single miR can regulate many fundamental cellular processes, such as cell proliferation, apoptosis, differentiation and migration. On the other hand, any gene can be regulated by multiple miRs (20). Alterations in miR expression are not simply an effect of tumorigenesis and may have a causative role in cancer development. ...
Recent studies show that microRNA (miRNAs) are involved in cancer by regulating cell proliferation, apoptosis and angiogenesis. Accordingly, their deregulation could contribute to cancer development and progression. It has been demonstrated that in ovarian tissue the over-expression of miR-199a and miR-125b inhibits tumor angiogenesis, a fundamental process for cancer development and growth. Aims of our study were to investigate the expression levels of miR-199a and miR-125b in serum of patients with ovarian cancer (OC) and to evaluate the correlation between miRNAs expression and traditional biomarkers [CA125 and human epididymis protein 4 (HE4)]. 32 patients with epithelial OC (54±14 years old) and 31 healthy controls (55±17 years old) were enrolled. Serum samples were collected prior to definitive surgical treatment and RNA extraction was performed by using the miRNeasy Serum/Plasma kit (Qiagen GmbH). miR-199a and miR-125b expression was determined by quantitative real timepolymerase chain reaction (TaqMan MicroRNA Assay, Applied Biosystems). The expression levels of miRNAs were normalized to miR-16 and calculated utilizing the 2-ΔCt method. Serum levels of miR-199a and miR-125b were significantly higher in OC patients compared to controls (P=0.007 and P=0.002, respectively). A marginally statistically significant correlation was found between miR-199a and miR-125b expression levels (r=0.38, P=0.03). The ROC curve analysis of the diagnostic performance between healthy controls and OC patients revealed that HE4 had a significantly higher area under the curve (AUC=0.90) when compared to CA125 (AUC=0.85), miR-199a (AUC=0.70) and miR-125b (AUC=0.67). Anyway, the determination of circulating miRNAs may be relevant, since their expression is known to be aberrant in cancer, having potential ability to monitor tumor dynamics.
... There is an increasing body of evidence demonstrating that microRNAs (miRNAs) are associated with regulation of distinct physio-pathological processes including development of normal stem cells and carcinogenesis [18,19]. MiRNAs are 21-25 nucleotides long, endogenously synthesized, noncoding RNAs that are involved in post-transcriptional gene silencing of target messenger RNAs (mRNAs) through binding 3′-untranslated regions (3′UTR) [20]. ...
Background
Emerging evidences proposed that microRNAs are associated with regulation of distinct physio-pathological processes including development of normal stem cells and carcinogenesis. In this study we aimed to investigate microRNA profile of cancer stem-like cells (CSLCs) isolated form freshly resected larynx cancer (LCa) tissue samples. MethodsCD133 positive (CD133+) stem-like cells were isolated from freshly resected LCa tumor specimens. MicroRNA profile of 12 pair of CD133+ and CD133− cells was determined using microRNA microarray and differential expressions of selvected microRNAs were validated by quantitative real time PCR (qRT-PCR). ResultsMicroRNA profiling of CD133+ and CD133− LCa samples with microarray revealed that miR-26b, miR-203, miR-200c, and miR-363-3p were significantly downregulated and miR-1825 was upregulated in CD133+ larynx CSLCs. qRT-PCR analysis in a total of 25 CD133+/CD133− sample pairs confirmed the altered expressions of these five microRNAs. Expressions of miR-26b, miR-200c, and miR-203 were significantly correlated with miR-363-3p, miR-203, and miR-363-3p expressions, respectively. Furthermore, in silico analysis revealed that these microRNAs target both cancer and stem-cell associated signaling pathways. Conclusions
Our results showed that certain microRNAs in CD133+ cells could be used as cancer stem cell markers. Based on these results, we propose that this panel of microRNAs might carry crucial roles in LCa pathogenesis through regulating stem cell properties of tumor cells.
Carbon-based quantum dots (CQDs) have been shown to have promising application value in tumor diagnosis. Their use, however, is severely hindered by the complicated nature of the nanostructures in the CQDs. Furthermore, it seems impossible to formulate the mechanisms involved using the inadequate theoretical frameworks that are currently available for CQDs. In this review, we re-consider the structure-property relationships of CQDs and summarize the current state of development of CQDs-based tumor diagnosis based on biological theories that are fully developed. The advantages and deficiencies of recent research on CQDs-based tumor diagnosis are thus explained in terms of the manifestation of nine essential changes in cell physiology. This review makes significant progress in addressing related problems encountered with other nanomaterials.
Intracellular cell signaling is a well understood process. However, extracellular signals such as hormones, adipokines, cytokines and neurotransmitters are just as important but have been largely ignored in other works. They are causative agents for diseases including hypertension, diabetes, heart disease, and arthritis so offer new, and often more approachable, targets for drug design. Aimed at medical professionals and pharmaceutical specialists, this book integrates extracellular and intracellular signalling processes and offers a fresh perspective on new drug targets. Written by colleagues at the same institution, but with contributions from leading international authorities, it is the result of close cooperation between the authors of different chapters. Readers are introduced to a new approach to disease causation by adipokines and toxic lipids. Heart disease, migraines, stroke, Alzheimer's disease, diabetes, cancer, and arthritis are approached from the perspective of prevention and treatment by alteration of extracellular signalling. Evidence is presented that the avoidance of toxic lifestyles can reduce the incidence of such illnesses and new therapeutic targets involving adipokines, ceramide and endocannabinoids are discussed.
Abstract— Cancer is the second leading cause of death in the world after cardiovascular disease. MicroRNAs (miRNAs) are a group of small non-coding RNAs with a length of about 19-25 nucleotides that are highly evolutionarily conserved and play an important role in regulating gene expression at the post-transcriptional level. They play a vital role in the body's biological processes such as cell cycle, cell growth, cell differentiation, and programmed cell death.
Objective: In this study, our aim is to investigate key miRNAs in cancer tissue based on the miRCancer online server
Materials and Methods: In this study, after downloading data from the miRCancer database, as an online source of micro-RNA validated data on cancer, the raw data were analyzed using grammatical codes in Excel software and the data normalized and visualized by Graphpad Prism software.
Results: Finally, we obtained 3 key microRNAs including has-miR-21, has-miR-145, and has-miR-34a, which were proven in 261, 144, and 137 in-vitro studies, respectively. Of these, has-miR-21 had high expression levels in 255 studies and low expression in only 6 studies. In contrast, two micro-RNAs, has-miR-145 and has-miR-34a, had low expression in most studies, And 125 studies were proven and only 10 and 12 studies had a high level of expression.
Conclusion: Three key microRNAs including has-miR-21, has-miR-145, and has-miR-34a were identified and introduced as promising targets in the treatment of various cancers.
Sensitive and accurate detection of nucleic acid biomarkers is critical for early cancer diagnosis, disease monitoring, and clinical treatment. In this study, we developed a switch fluorescence biosensor for simple and high-efficient detection of nucleic acid biomarkers using 6-carboxyfluorescein (FAM)-modified single-stranded DNA (ssDNA) probes (FAM-P1/P2), and zirconium porphyrin metal-organic framework nanoparticles (ZrMOF) acted as fluorescence quencher. FAM-P1/P2 probes were adsorbed on ZrMOF surface because of π-π stacking, hydrogen bonding, and electrostatic interactions. Fluorescence quenching event occurred by fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET) processes, thereby achieving the “off” fluorescence status. Once the specific binding was formed between the fluorescence probes and the targets, the rigid double-stranded DNA (dsDNA) structures were released from ZrMOF surface, resulting in the recovery of fluorescence and the “on” status. Because of the superior adsorption ability of ZrMOF toward ssDNA than dsDNA, the switch of fluorescence signals from “off” to “on” allowed rapid and ultrasensitive detection of ssDNA (T1) and microRNA-21 (miR-21) within 30 min. The limit of detection (signal-to-noise ratio = 3) for T1 and miR-21 were 2 fM and 11 aM, respectively. Moreover, the proposed strategy was very simple as it worked by the facile adsorption-quenching-recovery mechanism without difficult and complicated immobilization processes. Also, this biosensor showed an excellent analytical performance in the detection of miR-21 in human serum samples. Therefore, this biosensor might be considered a potential tool for the detection of DNA and miRNA biomarkers in clinical samples.
Glioma is the most common malignant brain tumor in central nervous system. Despite advances in the treatment of glioma such as surgery and chemoradiotherapy, most patients are easy to relapse, resulting in adverse clinical outcomes. Hence, effective molecular-targeting treatment may be one of attractive strategies for glioma therapy. The dysregulated microRNAs (miRNAs), one of the candidates of therapeutic targets, are believed to play an important role in the progression of glioma. In this study, we aimed to examine the expression profile of miRNAs in glioma and provide a reference for glioma therapy. Firstly, expression profile of miRNAs in 5 normal brain tissues, 5 low-grade glioma (LGG) tissues and 5 glioblastoma (GBM) tissues was detected by RNA sequencing (RNA-seq). Next, the target genes of differentially expressed miRNAs (DEmiRNAs) were predicted and then GO enrichment and KEGG pathway analysis performed by bioinformatics. Finally, 10 miRNAs which were significantly up- or down-regulated both in GBM and LGG were validated by real-time quantitative PCR (qRT-PCR). RNA-seq results indicated a number of DEmiRNAs in glioma. There were 64 up-regulated miRNAs and 17 down-regulated miRNAs in LGG, and 181 up-regulated miRNAs and 124 down-regulated miRNAs in GBM, respectively. Bioinformatics analysis showed that the target genes of these DEmiRNAs were enriched in various biological processes and signaling pathways such as cell metabolic and developmental process. Selected DEmiRNAs were further confirmed by qRT-PCR. miRNA-10b-5p, miRNA-92b-3p and miRNA-455-5p were significantly up-regulated in both GBM and LGG; while miRNA-542-3p was significantly up-regulated in LGG; miRNA-184 and miRNA-206 were significantly down-regulated in both GBM and LGG; miRNA-766-5p and miRNA-1-3p were significantly down-regulated in GBM. The subject of our study demonstrated several dysregulated miRNAs may serve as a potential therapeutic target for glioma.
Circular RNAs (circRNAs) are a type of tissue-specific RNA with more stable structure than linear RNAs, and its association with breast cancer (BC) is poorly understood. This study aimed at probing the biological effect of circ_0000043 in the progression of BC. In this study, expression of circ_0000043 in BC tissue samples was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemistry (IHC) and Western blot were used to detect the expression of Smad family member 3 (Smad3). CCK-8, wound healing and Transwell assays were used to assess the effect of circ_0000043 in regulating BC cell proliferation, migration and invasion. Moreover, the binding relationships between circ_0000043 and miR-136, and miR-136 and Smad3 were detected by dual-luciferase reporter assay. Additionally, Western blot was used to detect the expressions of markers related to epithelial-mesenchymal transition (EMT), including E-cadherin, N-cadherin and vimentin. Our results showed that circ_0000043 expression was up-regulated in BC tissues and cell lines. Proliferation, migration, invasion and EMT of BC cells were significantly inhibited by circ_0000043 knockdown, and overexpression of circ_0000043 had the opposite effects. Additionally, circ_0000043 could up-regulate Smad3 expression by sponging miR-136. In conclusion, our study demonstrates that circ_0000043 can promote BC progression via regulating the miR-136/Smad3 axis.
Backround: Pancreatic ductal adenocarcinoma (PDAC) is the most common and deadly cancer. Surgical resection is the only possible cure for pancreatic cancer but often has a poor prognosis, and the role of adjuvant therapy is urgently explored.
Methods:
MicroRNAs (miRNAs) play very important role in tumorigenesis by regulating the target genes. In this study, we identified miR-320b lower-expressed in human pancreatic cancer tissues but relatively higher-expressed in the adjacent nontumor tissues.
Results:
Consistently，the expression of miR-320b in different pancreatic cancer cell lines was significantly lower than the normal pancreatic cells. In order to identify the effects of miR-320b on cell growth, we overexpressed miR-320b in PANC-1 and FG pancreatic cancer cell lines, CCK8 and BrdU incorporation assay results showed that miR-320b inhibited cell proliferation.
Discussion:
We next predicted miR-20b targeted FOXM1（Forkhead box protein M1）and identified the negative relationship between miR-320b and FOXM1.We also demonstrated that elevated miR-320b expression inhibited tumor growth in vivo.
Conclusion:
All of these results showed that miR-320b suppressed pancreatic cancer cells proliferation by targeting FOXM1, which might provide a new diagnostic marker for pancreatic cancer.
Lung cancer is one of the most common cancers and its incidence is rising around the world. Various studies suggest that miR‐330 acts as a tumor‐suppressor microRNA (miRNA) in different types of cancers, but precisely how has remained unclear. In this study, we investigate miR‐330 expression in lung cancer patient samples, as well as in vitro, by studying how normalization of miR‐330 expression affects lung cancer cellular phenotypes such as viability, apoptosis, proliferation, and migration. We establish that low miR‐330 expression predicts poor lung cancer prognosis. Stable restoration of reduced miR‐330 expression in lung cancer cells reduces cell viability, increases the fraction of apoptotic cells, causes G2/M cell cycle arrest, and inhibits cell migration. These findings are substantiated by increased mRNA and protein expression of markers for apoptosis via the intrinsic pathway, such as caspase 9, and decreased mRNA and protein expression of markers for cell migration, such as vimentin, C‐X‐C chemokine receptor type 4, and matrix metalloproteinase 9. We showed that reduced miR‐330 expression predicts poor lung cancer survival and that stable restoration of miR‐330 expression in lung cancer cells has a broad range of tumor‐suppressive effects. This indicates that miR‐330 is a promising candidate for miRNA replacement therapy for lung cancer patients. We showed that reduced miR‐330 expression predicts poor lung cancer survival and that stable restoration of miR‐330 expression in lung cancer cells has a broad range of tumor‐suppressive effects. This indicates that miR‐330 is a promising candidate for miRNA replacement therapy for lung cancer patients.
MicroRNAs are small noncoding transcripts that posttranscriptionally regulate gene expression via base-pairing complementarity. Their role in cancer can be related to tumor suppression or oncogenic function. Moreover, they have been linked to processes recognized as hallmarks of cancer, such as apoptosis, invasion, metastasis, and proliferation. Particularly, one of the first oncomiRs found upregulated in a variety of cancers -such as gliomas, breast and colorectal cancer- was microRNA-21 (miR-21). Some of its target genes associated with cancer are PTEN, PDCD4, RECK, and STAT3. As a result, miR-21 has been proposed as a plausible diagnostic and prognostic biomarker, as well as a therapeutic target for several types of cancer. Currently, research and clinical trials to inhibit miR-21 through anti-miR-21 oligos and ADM-21 are being conducted. As all the evidence suggests, miR-21 is involved in carcinogenic processes; therefore, inhibiting it could have effects on more than one type of cancer. However, whether miR-21 can be used as a tissue-specific biomarker should be analysed with caution. Consequently, the purpose of this review is to outline the available information and recent advances regarding miR-21 as a potential biomarker in the clinical setting and as a therapeutic target in cancer to highlight its importance in the era of precision medicine.
Background
Gastric cancer (GC) patients are usually diagnosed in advanced stages which results in high mortality. This study aimed to identify novel circulating miRNAs as biomarkers for the early detection of GC.
Methods
Candidate miRNA was identified after integrated analysis of two Gene Expression Omnibus (GEO) datasets and clinical serum samples. Exosomes extracted were verified using transmission electron microscopy (TEM) and western blot. The expressions of miRNAs were tested through qRT-PCR. Receiver operating characteristic curve (ROC) analysis was used to explore the diagnostic utility of miRNAs. RNA pull-down assay was used to find RNA binding proteins (RBPs) which transport candidate miRNA into exosomes. Bioinformatics analysis of candidate miRNA was conducted using DAVID and Cytoscape.
Results
After integrated analysis of two GEO datasets, six circulating miRNAs were found to be consistently upregulated in GC patients. Then, qRT-PCR demonstrated that serum miR-1246 was the one with the largest fold change. Studies in vitro revealed that elevated serum miR-1246 was tumor-derived by being packaged into exosomes with the help of ELAVL1. Thereafter, we discovered that exosomal miR-1246 expressions in serum could differentiate GC patients with TNM stage I from healthy controls (HCs) and patients with benign diseases (BDs) with area under the curve (AUC) of 0.843 and 0.811, respectively. Bioinformatics analysis revealed miR-1246, as a tumor suppressor in GC, could regulate several signaling pathways.
Conclusion
Circulating exosomal miR-1246 was a potential biomarker for the early diagnosis of GC.
Gastric cancer (GC) is a frequent type of malignant tumor worldwide. GC metastasis results in the majority of clinical treatment failures. MicroRNAs (miRNA) are identified to exhibit crucial roles in GC. Our current study aimed to explore the biological roles of miR‐505 in GC progression. It was observed that miR‐505 was robustly decreased in GC cells compared with human normal gastric epithelial GES‐1 cells. Overexpression of miR‐505 was able to repress GC progression in AGS and BGC‐823 cells. In addition, high‐mobility group box 1 (HMGB1) has been identified as a crucial oncogene in several cancer types. By carrying out bioinformatics analysis, HMGB1 was predicted as a direct target of miR‐505. Meanwhile, HMGB1 was found to be significantly increased in GC cells and it was confirmed in our study that miR‐505 can directly target HMGB1 in vitro. miR‐505 mimics can inhibit HMGB1 messenger RNA and protein expression dramatically. Subsequently, knockdown of HMGB1 can inhibit GC cell proliferation, colony formation, and induce cell apoptosis. Furthermore, HMGB1 silence suppressed GC cell migration and invasion greatly in vitro. Finally, it was validated that miR‐505 can inhibit GC progression by targeting HMGB1 in vivo. Taken these together, it was indicated that miR‐505/HMGB1 axis was involved in the development of GC. miR‐505 can serve as a potential prognostic indicator in GC therapy. This is the first report on the biological roles of miR‐505 in gastric cancer (GC) development. The tumor suppressive role of miR‐505 was validated both in vitro and in vivo. miR‐505/high‐mobility group box 1 axis participated in GC progression and miR‐505 can be indicated as a novel GC biomarker.
Histopathology plays an important role in defining response to treatment for different tumor types. Histopathologic response criteria are currently used as reference standard in various types of cancer, including breast cancer, gastroesophageal cancer, and bone tumors. Since there were no generally accepted response criteria established for ovarian cancer, a systematic analysis of various features of tumor regression was performed. Patient survival served as the reference standard to validate the histopathologic features of tumor regression. In contrast to ovarian cancer, borderline ovarian tumors are epithelial ovarian neoplasms characterized by up-regulated cellular proliferation and cytologic atypia but without destructive stromal invasion. While borderline ovarian tumors generally have an excellent prognosis with a 5‑year survival of > 95%, recurrences and malignant transformation occur in a small percentage of patients. Nevertheless, the identification of patients at increased risk for recurrence remains difficult. The aim of studying histopathological markers in ovarian cancers and borderline tumors was to evaluate whether histopathologic features including molecular pathologic alterations can predict patient outcome, particularly the risk of recurrence of serous and mucinous borderline tumors.
Epithelial-mesenchymal transition (EMT) plays an important role in breast cancer cell metastasis. Both (megakaryoblastic leukemia)/myocardin-like 1 (MKL-1) and Signal transducer and activator of transcription 3 (STAT3) have been implicated in the control of cellular metabolism, survival and growth. Our previous study has shown that cooperativity of MKL-1 and STAT3 promoted breast cancer cell migration. Herein, we demonstrate a requirement for MKL-1 and STAT3 in miRNA-mediated cellular EMT to affect breast cancer cell migration. Here we show that cooperativity of MKL-1 and STAT3 promoted the EMT of MCF-7 cells. Importantly, MKL-1 and STAT3 promoted the expression of Vimentin via its promoter CArG box. Interestingly, miR-93-5p inhibits the EMT of breast cancer cells through suppressing the expression of MKL-1 and STAT3 via targeted their 3’UTR. These results demonstrated a novel pathway through which miR-93-5p regulates MKL-1 and STAT3 to affect EMT controlling breast cancer cell migration.
Stem cells (SCs) are able to differentiate into many different cell types of the body during early life and growth. They are unspecialized cells capable of self-renewal and, when challenged, they can be induced to differentiate into specific and mature cell types. SCs can be classified into two different types: somatic stem cells (SSCs) and embryonic stem cells (ESCs). One major problem concerning in vitro SC culture is the difficulty to maintain their genetic and karyotype integrity during long-term culture. This chapter describes the different types of abnormalities accumulated by ESCs, derived from different species, and SSCs, of different somatic origin, during long-term culture in vitro. It outlines the main processes that are implicated in the onset of chromosome abnormalities in cells during culture. Among these processes, only one has been so far described in SCs.
MicroRNAs (miRNAs) are 21-23 nucleotide RNA molecules that regulate the stability or translational efficiency of target messenger RNAs. miRNAs have diverse functions, including the regulation of cellular differentiation, proliferation and apoptosis. Although strict tissue- and developmental-stage-specific expression is critical for appropriate miRNA function, mammalian transcription factors that regulate miRNAs have not yet been identified. The proto-oncogene c-MYC encodes a transcription factor that regulates cell proliferation, growth and apoptosis. Dysregulated expression or function of c-Myc is one of the most common abnormalities in human malignancy. Here we show that c-Myc activates expression of a cluster of six miRNAs on human chromosome 13. Chromatin immunoprecipation experiments show that c-Myc binds directly to this locus. The transcription factor E2F1 is an additional target of c-Myc that promotes cell cycle progression. We find that expression of E2F1 is negatively regulated by two miRNAs in this cluster, miR-17-5p and miR-20a. These findings expand the known classes of transcripts within the c-Myc target gene network, and reveal a mechanism through which c-Myc simultaneously activates E2F1 transcription and limits its translation, allowing a tightly controlled proliferative signal.
The E2 factor (E2F) family of transcription factors are downstream targets of the retinoblastoma protein. E2F factors have been known for several years to be important regulators of S-phase entry. Recent studies have improved our understanding of the molecular mechanisms of action used by this transcriptional network. In addition, they have given us an appreciation of the fact that E2F has functions that reach beyond G1/S control and impact cell proliferation in several different ways. The discovery of new family members with unusual properties, the unexpected phenotypes of mutant animals, a diverse collection of biological activities, a large number of new putative target genes and the new modes of transcriptional regulation have all contributed to an increasingly complex view of E2F function. In this review, we will discuss these recent developments and describe how they are beginning to shape a new and revised picture of the E2F transcriptional program.
Micro-RNAs (miR genes) are a large family of highly conserved noncoding genes thought to be involved in temporal and tissue-specific gene regulation. MiRs are transcribed as short hairpin precursors ( approximately 70 nt) and are processed into active 21- to 22-nt RNAs by Dicer, a ribonuclease that recognizes target mRNAs via base-pairing interactions. Here we show that miR15 and miR16 are located at chromosome 13q14, a region deleted in more than half of B cell chronic lymphocytic leukemias (B-CLL). Detailed deletion and expression analysis shows that miR15 and miR16 are located within a 30-kb region of loss in CLL, and that both genes are deleted or down-regulated in the majority ( approximately 68%) of CLL cases.
Short non-coding RNAs are known to regulate cellular processes including development, heterochromatin formation, and genomic stability in eukaryotes. Given the impact of these processes on cellular identity, a study was undertaken to investigate possible changes in microRNA (miRNA) levels during tumorigenesis. A total of 28 different miRNA sequences was identified in a colonic adenocarcinoma and normal mucosa, including 3 novel sequences and a further 7 that had previously been cloned only from mice. Human homologues of murine miRNA sequences, miR-143 and miR-145, consistently display reduced steady-state levels of the mature miRNA at the adenomatous and cancer stages of colorectal neoplasia.
MicroRNAs (miRNAs) are small RNAs that regulate the expression of complementary messenger RNAs. Hundreds of miRNA genes have been found in diverse animals, and many of these are phylogenetically conserved. With miRNA roles identified in developmental timing, cell death, cell proliferation, haematopoiesis and patterning of the nervous system, evidence is mounting that animal miRNAs are more numerous, and their regulatory impact more pervasive, than was previously suspected.
MicroRNAs (miRNAs) are regulatory RNAs found in multicellular eukaryotes, including humans, where they are implicated in cancer. The let-7 miRNA times seam cell terminal differentiation in C. elegans. Here we show that the let-7 family negatively regulates let-60/RAS. Loss of let-60/RAS suppresses let-7, and the let-60/RAS 3'UTR contains multiple let-7 complementary sites (LCSs), restricting reporter gene expression in a let-7-dependent manner. mir-84, a let-7 family member, is largely absent in vulval precursor cell P6.p at the time that let-60/RAS specifies the 1 degrees vulval fate in that cell, and mir-84 overexpression suppresses the multivulva phenotype of activating let-60/RAS mutations. The 3'UTRs of the human RAS genes contain multiple LCSs, allowing let-7 to regulate RAS expression. let-7 expression is lower in lung tumors than in normal lung tissue, while RAS protein is significantly higher in lung tumors, providing a possible mechanism for let-7 in cancer.
MicroRNAs are small noncoding RNAs that recognize and bind to partially complementary sites in the 3' untranslated regions of target genes in animals and, by unknown mechanisms, regulate protein production of the target transcript. Different combinations of microRNAs are expressed in different cell types and may coordinately regulate cell-specific target genes. Here, we present PicTar, a computational method for identifying common targets of microRNAs. Statistical tests using genome-wide alignments of eight vertebrate genomes, PicTar's ability to specifically recover published microRNA targets, and experimental validation of seven predicted targets suggest that PicTar has an excellent success rate in predicting targets for single microRNAs and for combinations of microRNAs. We find that vertebrate microRNAs target, on average, roughly 200 transcripts each. Furthermore, our results suggest widespread coordinate control executed by microRNAs. In particular, we experimentally validate common regulation of Mtpn by miR-375, miR-124 and let-7b and thus provide evidence for coordinate microRNA control in mammals.
MicroRNAs (miRNAs) are small noncoding RNAs, about 21 nucleotides in length, that can regulate gene expression by base-pairing
to partially complementary mRNAs. Regulation by miRNAs can play essential roles in embryonic development. We determined the
temporal and spatial expression patterns of 115 conserved vertebrate miRNAs in zebrafish embryos by microarrays and by in
situ hybridizations, using locked-nucleic acid–modified oligonucleotide probes. Most miRNAs were expressed in a highly tissue-specific
manner during segmentation and later stages, but not early in development, which suggests that their role is not in tissue
fate establishment but in differentiation or maintenance of tissue identity.
Recent work has revealed the existence of a class of small non-coding RNA species, known as microRNAs (miRNAs), which have critical functions across various biological processes. Here we use a new, bead-based flow cytometric miRNA expression profiling method to present a systematic expression analysis of 217 mammalian miRNAs from 334 samples, including multiple human cancers. The miRNA profiles are surprisingly informative, reflecting the developmental lineage and differentiation state of the tumours. We observe a general downregulation of miRNAs in tumours compared with normal tissues. Furthermore, we were able to successfully classify poorly differentiated tumours using miRNA expression profiles, whereas messenger RNA profiles were highly inaccurate when applied to the same samples. These findings highlight the potential of miRNA profiling in cancer diagnosis.
To date, more than 200 microRNAs have been described in humans; however, the precise functions of these regulatory, non-coding RNAs remains largely obscure. One cluster of microRNAs, the mir-17-92 polycistron, is located in a region of DNA that is amplified in human B-cell lymphomas. Here we compared B-cell lymphoma samples and cell lines to normal tissues, and found that the levels of the primary or mature microRNAs derived from the mir-17-92 locus are often substantially increased in these cancers. Enforced expression of the mir-17-92 cluster acted with c-myc expression to accelerate tumour development in a mouse B-cell lymphoma model. Tumours derived from haematopoietic stem cells expressing a subset of the mir-17-92 cluster and c-myc could be distinguished by an absence of apoptosis that was otherwise prevalent in c-myc-induced lymphomas. Together, these studies indicate that non-coding RNAs, specifically microRNAs, can modulate tumour formation, and implicate the mir-17-92 cluster as a potential human oncogene.
lin-4 is essential for the normal temporal control of diverse postembryonic developmental events in C. elegans. lin-4 acts by negatively regulating the level of LIN-14 protein, creating a temporal decrease in LIN-14 protein starting in the first larval stage (L1). We have cloned the C. elegans lin-4 locus by chromosomal walking and transformation rescue. We used the C. elegans clone to isolate the gene from three other Caenorhabditis species; all four Caenorhabditis clones functionally rescue the lin-4 null allele of C. elegans. Comparison of the lin-4 genomic sequence from these four species and site-directed mutagenesis of potential open reading frames indicated that lin-4 does not encode a protein. Two small lin-4 transcripts of approximately 22 and 61 nt were identified in C. elegans and found to contain sequences complementary to a repeated sequence element in the 3' untranslated region (UTR) of lin-14 mRNA, suggesting that lin-4 regulates lin-14 translation via an antisense RNA-RNA interaction.
The C. elegans heterochronic gene pathway consists of a cascade of regulatory genes that are temporally controlled to specify the timing of developmental events. Mutations in heterochronic genes cause temporal transformations in cell fates in which stage-specific events are omitted or reiterated. Here we show that let-7 is a heterochronic switch gene. Loss of let-7 gene activity causes reiteration of larval cell fates during the adult stage, whereas increased let-7 gene dosage causes precocious expression of adult fates during larval stages. let-7 encodes a temporally regulated 21-nucleotide RNA that is complementary to elements in the 3' untranslated regions of the heterochronic genes lin-14, lin-28, lin-41, lin-42 and daf-12, indicating that expression of these genes may be directly controlled by let-7. A reporter gene bearing the lin-41 3' untranslated region is temporally regulated in a let-7-dependent manner. A second regulatory RNA, lin-4, negatively regulates lin-14 and lin-28 through RNA-RNA interactions with their 3' untranslated regions. We propose that the sequential stage-specific expression of the lin-4 and let-7 regulatory RNAs triggers transitions in the complement of heterochronic regulatory proteins to coordinate developmental timing.
MicroRNAs (miRNAs) are endogenous approximately 22 nt RNAs that can play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression. Although they escaped notice until relatively recently, miRNAs comprise one of the more abundant classes of gene regulatory molecules in multicellular organisms and likely influence the output of many protein-coding genes.
MicroRNAs are a family of small, non-coding RNAs that regulate gene expression in a sequence-specific manner. The two founding members of the microRNA family were originally identified in Caenorhabditis elegans as genes that were required for the timed regulation of developmental events. Since then, hundreds of microRNAs have been identified in almost all metazoan genomes, including worms, flies, plants and mammals. MicroRNAs have diverse expression patterns and might regulate various developmental and physiological processes. Their discovery adds a new dimension to our understanding of complex gene regulatory networks.
We sequenced 122 miRNAs in 10 primate species to reveal conservation characteristics of miRNA genes. Strong conservation is observed in stems of miRNA hairpins and increased variation in loop sequences. Interestingly, a striking drop in conservation was found for sequences immediately flanking the miRNA hairpins. This characteristic profile was employed to predict novel miRNAs using cross-species comparisons. Nine hundred and seventy-six candidate miRNAs were identified by scanning whole-genome human/mouse and human/rat alignments. Most of the novel candidates are conserved also in other vertebrates (dog, cow, chicken, opossum, zebrafish). Northern blot analysis confirmed the expression of mature miRNAs for 16 out of 69 representative candidates. Additional support for the expression of 179 novel candidates can be found in public databases, their presence in gene clusters, and literature that appeared after these predictions were made. Taken together, these results suggest the presence of significantly higher numbers of miRNAs in the human genome than previously estimated.
We predict regulatory targets of vertebrate microRNAs (miRNAs) by identifying mRNAs with conserved complementarity to the seed (nucleotides 2-7) of the miRNA. An overrepresentation of conserved adenosines flanking the seed complementary sites in mRNAs indicates that primary sequence determinants can supplement base pairing to specify miRNA target recognition. In a four-genome analysis of 3' UTRs, approximately 13,000 regulatory relationships were detected above the estimate of false-positive predictions, thereby implicating as miRNA targets more than 5300 human genes, which represented 30% of our gene set. Targeting was also detected in open reading frames. In sum, well over one third of human genes appear to be conserved miRNA targets.
MicroRNAs constitute a growing class of non-coding RNAs that are thought to regulate gene expression via translational repression. MicroRNAs are initially transcribed as several hundred-nucleotide pri-miRNAs and are then processed to approximately 60-nucleotide hairpin pre-miRNAs. We hypothesized that polymorphisms in both pre-miRNA and mature microRNA modify various biological processes by influencing the processing and/or target selection of microRNAs. In the present study, we sequenced 173 human pre-miRNA genome regions in 96 subjects and found 10 polymorphisms in the 10 pre-miRNA hairpin regions. Although most of these polymorphisms seem to have no effect on microRNA processing, we identified a C to A polymorphism in the mature miR-30c-2 sequence. This polymorphism may alter target selection and thus exert profound biological effects. To the best of our knowledge, this is the first report of polymorphisms in pre-miRNAs.
Although they are tiny, microRNAs can have large-scale effects because
they regulate a variety of genes. These minuscule molecules are now
definitively linked to the development of cancer.
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