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BMS-536924 blocks acinar proliferation, partially restores polarization, and induces apoptosis in CD8-IGF-IR-MCF10A acini
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This study aimed to test the ability of a new insulin-like growth factor receptor (IGF-IR) tyrosine kinase inhibitor, BMS-536924, to reverse the ability of constitutively active IGF-IR (CD8-IGF-IR) to transform MCF10A cells, and to examine the effect of the inhibitor on a range of human breast cancer cell lines.
CD8-IGF-IR-MCF10A cells were grown i...
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... high degree of proliferation likely contributed to expansion and overgrowth of the acini. Consistent with IGF-IR stimulating survival and luminal filling, CD8-IGF-IR showed little or no apoptosis in the luminal space as assessed by CC3 staining (data not shown and Fig 2C). Additionally, pBabe-MCF10A cells showed a polarized layer of cells as described by others [37], whereas CD8-IGF-IR-MCF10A cells lost polarity as indicated by aberrant deposition of LamininV in the luminal space (Supplementary Figure 1). ...
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... the effect of BMS-536924 on proliferation and apicobasal polarization, pBabe-MCF10A and CD8-IGF-IR-MCF10A cells were cultured in Matrigel and treated with 1μM BMS-536924 every 4 days. BMS-536924 inhibited growth with both pBabe- MCF10A and CD8-IGF-IR-MCF10A acini being smaller in size and a reduction of more than 80% of Ki67-positive cells ( Fig. 2A and quantified in 2B) The size reduction was more dramatic in CD8-IGF-IR-overexpressing cells but most strikingly, BMS-536924 treatment of CD8-IGF- IR-MCF10A cells resulted in the formation of acini that resembled the MCF10A acini, and we didn't observe any large multilobular structures ( Fig. 2A). BMS-536924 treatment of CD8- ...
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... of more than 80% of Ki67-positive cells ( Fig. 2A and quantified in 2B) The size reduction was more dramatic in CD8-IGF-IR-overexpressing cells but most strikingly, BMS-536924 treatment of CD8-IGF- IR-MCF10A cells resulted in the formation of acini that resembled the MCF10A acini, and we didn't observe any large multilobular structures ( Fig. 2A). BMS-536924 treatment of CD8- IGF-IR-MCF10A cells resulted in acini with distinct polarization and lamininV deposition to the basal surface of the acini and a disappearance of lamininV from the lumen (Fig. 2A). Therefore, BMS-536924 is able to partially reverse IGF-IR mediated disruption of proliferation and polarization and results in ...
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... cells resulted in the formation of acini that resembled the MCF10A acini, and we didn't observe any large multilobular structures ( Fig. 2A). BMS-536924 treatment of CD8- IGF-IR-MCF10A cells resulted in acini with distinct polarization and lamininV deposition to the basal surface of the acini and a disappearance of lamininV from the lumen (Fig. 2A). Therefore, BMS-536924 is able to partially reverse IGF-IR mediated disruption of proliferation and polarization and results in the formation of acini that resemble normal MCF10A cells. These results are similar to those results originally observed with targeting β1-integrin that led to a reversion of the malignant phenotype and ...
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... were cultured in matrigel for 12 days, and then treated for 4 days with 1μM BMS-536924. At day 16 acini were harvested, fixed, and stained for cleaved caspase 3 (CC3) as a marker for apoptosis, and Ki67 as a marker of proliferation. At day 16, pBabe-MCF10A acini showed little or no proliferation either in the presence or absence of BMS-536924 (Fig. 2C). In contrast, CD8-IGF-IR-MCF10A acini were large and hyperproliferative, and treatment with BMS-536924 caused a dramatic reduction in Ki67 staining (Fig. 2C). CC3 was not detectable in untreated pBabe-MCF10A acini whereas treatment with BMS-536924 resulted in the detection of cells positive for CC3, indicating a role for IGF-IR in ...
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... 3 (CC3) as a marker for apoptosis, and Ki67 as a marker of proliferation. At day 16, pBabe-MCF10A acini showed little or no proliferation either in the presence or absence of BMS-536924 (Fig. 2C). In contrast, CD8-IGF-IR-MCF10A acini were large and hyperproliferative, and treatment with BMS-536924 caused a dramatic reduction in Ki67 staining (Fig. 2C). CC3 was not detectable in untreated pBabe-MCF10A acini whereas treatment with BMS-536924 resulted in the detection of cells positive for CC3, indicating a role for IGF-IR in survival of MCF10A cells in culture. More importantly, treatment of CD8- IGF-IR-MCF10A cells with BMS-536924 resulted in a dramatic induction of apoptosis, with ...
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... in untreated pBabe-MCF10A acini whereas treatment with BMS-536924 resulted in the detection of cells positive for CC3, indicating a role for IGF-IR in survival of MCF10A cells in culture. More importantly, treatment of CD8- IGF-IR-MCF10A cells with BMS-536924 resulted in a dramatic induction of apoptosis, with up to 40% of CC3 positive cells (Fig. 2C and quantified in 2D). Interestingly, the majority of the staining was in the center of the largely misshapen acini, but we also noted apoptotic cells in the outer layer. Despite this large increase in apoptosis, we didn't observe a complete elimination of cells in the center of the lumen. Even a longer incubation with BMS-536924 for 6 days after 12 days of ...
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Citations
... 28,29 The BMS-536924, which is a dual insulin receptor (IR) and insulin-like growth factor-1 receptor (IGF1R) inhibitor, had also shown anti-proliferative and proapoptotic effects in vitro and in vivo. 30 Fedratinib, a drug mainly used to treat myeloproliferative neoplasm (MPN)-associated myelofibrosis, acts as a competitive inhibitor of protein kinases JAK-1, JAK-2, and FLT3, was another drug with the potential of reversing the LUAD expression profile. 31 The mitogen-activated protein kinase (MEK) inhibitor Selumetinib and the HDAC inhibitor Vorinostat were the two other probable drugs capable of reversing the transcription signature in LUAD. ...
Lung adenocarcinoma is one of the leading causes of cancer-related mortality globally. Various treatment approaches and drugs had little influence on overall survival; thus, new drugs and treatment strategies are needed. Drug repositioning (repurposing) seems a favorable approach considering that developing new drugs needs much more time and costs. We performed a meta-analysis on 6 microarray datasets to obtain the main genes with significantly altered expression in lung adenocarcinoma. Following that, we found major gene clusters and hub genes. We assessed their enrichment in biological pathways to get insight into the underlying biological process involved in lung adenocarcinoma pathogenesis. The L1000 database was explored for drug perturbations that might reverse the expression of differentially expressed genes in lung adenocarcinoma. We evaluated the potential drug combinations that interact the most with hub genes and hence have the most potential to reverse the disease process. A total of 2148 differentially expressed genes were identified. Six main gene clusters and 27 significant hub genes mainly involved in cell cycle regulation have been identified. By assessing the interaction between 3 drugs and hub genes and information gained from previous clinical investigations, we suggested the three possible repurposed drug combinations, Vorinostat – Dorsomorphin, PP-110 – Dorsomorphin, and Puromycin – Vorinostat with a high chance of success in clinical trials.
... Moreover, BMS-754807 has been known to have off-target effects in inhibiting the activation of tropomyosin-receptor-kinase A and B (TrkA and TrkB) and aurora kinases in pancreatic cancer [65], which influenced their therapeutic efficacy. However, some TKIs have exhibited promising preclinical activity in vitro; a few TKIs, including NVP-AEW541 [69], AZ12253801 [70] and BMS-536924 [71], have undergone clinical evaluation, and the results obtained have resulted in their termination. In addition, some TKIs belong to non-ATP competitive antagonists, which only inhibit IGF-1R; the INSR signaling is not affected, and these TKIs also suppress additional related genes. ...
In addition to the fundamental role of insulin-like growth factor (IGF)/IGF-1 receptor (IGF-1R) signaling dysregulation in cancer initiation and proliferation, the IGF/IGF-1R signaling also plays an important role in the maintenance of stem cell characteristics and enhancement of stem cell-based therapeutic efficacy. This review focused on the role of IGF/IGF-1R signaling in preclinical IGF-targeted therapies, including IGF-1R monoclonal antibodies, IGF-1R tyrosine kinase inhibitors, and neutralizing antibodies of IGFs in multiple tumors and endocrine disorders. On the other hand, the function of IGF/IGF-1R signaling in stem cell self-renewal, pluripotency and therapeutic efficacy in regenerative medicine was outlined. Finally, the review summarized ongoing studies on IGF/IGF-1R signaling blockade in multiple cancers and highlighted the IGF-1R signaling modifications in stem cells as a potential strategy to improve stem cell-based therapeutics in regenerative medicine.
... Aberrant regulation of the IGF1R signaling pathway has been recognized as a well-established therapeutic target in a variety of human malignancies, including SCLC [29,30]. BMS-536924, an ATP-competitive IGF1R inhibitor, can suppress the IGF1R-induced phosphorylation of phosphoinositide 3-kinase (PI3K)/ protein kinase B (AKT), consequently repressing cancer cell proliferation and differentiation [31][32][33][34]. ...
... BMS-536924, a small molecule inhibitor targeting IGF1R, has been confirmed to suppress IGF1R phosphorylation and block IGF1R-mediated activation of AKT signaling cascades [33]. Addition of BMS-536924 could attenuate the expression of p-AKT and p-S6RP protein, but this negative regulation of AKT signaling cascade was diminished upon circVAPA overexpression (Fig. 6D). ...
Background
Multiple lines of evidence have demonstrated that circular RNAs (circRNAs) play oncogenic or tumor-suppressive roles in various human cancers. Nevertheless, the biological functions of circRNAs in small cell lung cancer (SCLC) are still elusive.
Methods
CircVAPA (annotated as hsa_circ_0006990) was identified by mining the circRNA profiling dataset of six paired SCLC tissues and the RNA-seq data of serum samples from 36 SCLC patients and 118 healthy controls. The circVAPA expression level was evaluated using quantitative real-time PCR in SCLC cells and tissues. Cell viability, colony formation, cell cycle and apoptosis analysis assays and in vivo tumorigenesis were used to reveal the biological roles of circVAPA . The underlying mechanism of circVAPA was investigated by Western blot, RNA pulldown, RNA immunoprecipitation, dual-luciferase reporter assay and rescue experiments.
Results
We revealed that circVAPA , derived from exons 2-4 of the vesicle-associated membrane protein-associated protein A (VAPA) gene, exhibited higher expression levels in SCLC cell lines, clinical tissues, and serum from SCLC patients than the controls, and facilitated SCLC progression in vitro and in vivo . Mechanistically, circVAPA activated the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway by modulating the miR-377-3p and miR-494-3p /insulin-like growth factor 1 receptor (IGF1R) axis to accelerate SCLC progression. Furthermore, circVAPA depletion markedly enhanced the inhibitory effects of BMS-536924, an IGF1R kinase inhibitor in cellular and xenograft mouse models.
Conclusions
CircVAPA promotes SCLC progression via the miR-377-3p and miR-494-3p /IGF1R/AKT axis. We hope to develop clinical protocols of combinations of circVAPA inhibition and BMS-536924 addition for treating SCLC with circVAPA upregulation.
... As one of the activators of Akt, the IGF1 pathway has long been associated with breast cancer progression (14)(15)(16)(17)(18). IGF1 is an essential component in cellular proliferation and survival (15,19). Binding of IGF1 to its receptor (IGF1R) or the insulin receptor (IR) stimulates autophosphorylation and activation of the PI3K and MAPK pathways among others (15,18,20). ...
... We specifically examined the effects of E-cadherin deletion on FGFR activity given recent studies on the role of FGFR4 as a driver of endocrine resistance (50), particularly in ILC (51). Cells were stimulated with a cocktail of FGF ligands (FGF 1,2,4,6,8,17,19,21, and 23) resulting in strong enhancement in both raw and normalized pFGFR4 levels in both MCF7 and T47D CDH1 KO cells, despite decreased total FGFR4 levels in the CDH1 KO cells (Supplementary Fig. S2B). Surprisingly, although pFGFR4 was elevated in CDH1 KO cells, downstream activators did not display a difference between WT and CDH1 KO cells. ...
No special-type breast cancer [NST; commonly known as invasive ductal carcinoma (IDC)] and invasive lobular carcinoma (ILC) are the two major histological subtypes of breast cancer with significant differences in clinicopathological and molecular characteristics. The defining pathognomonic feature of ILC is loss of cellular adhesion protein, E-cadherin (CDH1). We have previously shown that E-cadherin functions as a negative regulator of the IGF1R and propose that E-cadherin loss in ILC sensitizes cells to growth factor signaling that thus alters their sensitivity to growth factor–signaling inhibitors and their downstream activators. To investigate this potential therapeutic vulnerability, we generated CRISPR-mediated CDH1 knockout (CDH1 KO) IDC cell lines (MCF7, T47D, and ZR75.1) to uncover the mechanism by which loss of E-cadherin results in IGF pathway activation. CDH1 KO cells demonstrated enhanced invasion and migration that was further elevated in response to IGF1, serum and collagen I. CDH1 KO cells exhibited increased sensitivity to IGF resulting in elevated downstream signaling. Despite minimal differences in membranous IGF1R levels between wild-type (WT) and CDH1 KO cells, significantly higher ligand–receptor interaction was observed in the CDH1 KO cells, potentially conferring enhanced downstream signaling activation. Critically, increased sensitivity to IGF1R, PI3K, Akt, and MEK inhibitors was observed in CDH1 KO cells and ILC patient-derived organoids.
Implications
Overall, this suggests that these targets require further exploration in ILC treatment and that CDH1 loss may be exploited as a biomarker of response for patient stratification.
... PPT was also evidenced to suppress the capacity of CD24 − CD44 + BC stem cells to undergo the EMT process (Chang et al., 2013). Promising experimental data have been provided using a dual IGF-1R/IR tyrosine kinase inhibitor, named BMS-536924, which showed the capability to prevent proliferative and migratory features of BC cells (Law et al., 2008;Litzenburger et al., 2009), without adverse effects associated with the insulin deficiency (Dool et al., 2011). Furthermore, a tyrosine kinase inhibitor targeting both IGF-1R and IR, named BMS-754807, triggered an inhibitory response in TNBC cells characterized by an IGF signature (Litzenburger et al., 2011). ...
The development and progression of the great majority of breast cancers (BCs) are mainly dependent on the biological action elicited by estrogens through the classical estrogen receptor (ER), as well as the alternate receptor named G-protein–coupled estrogen receptor (GPER). In addition to estrogens, other hormones and growth factors, including the insulin and insulin-like growth factor system (IIGFs), play a role in BC. IIGFs cooperates with estrogen signaling to generate a multilevel cross-communication that ultimately facilitates the transition toward aggressive and life-threatening BC phenotypes. In this regard, the majority of BC deaths are correlated with the formation of metastatic lesions at distant sites. A thorough scrutiny of the biological and biochemical events orchestrating metastasis formation and dissemination has shown that virtually all cell types within the tumor microenvironment work closely with BC cells to seed cancerous units at distant sites. By establishing an intricate scheme of paracrine interactions that lead to the expression of genes involved in metastasis initiation, progression, and virulence, the cross-talk between BC cells and the surrounding microenvironmental components does dictate tumor fate and patients’ prognosis. Following (i) a description of the main microenvironmental events prompting BC metastases and (ii) a concise overview of estrogen and the IIGFs signaling and their major regulatory functions in BC, here we provide a comprehensive analysis of the most recent findings on the role of these transduction pathways toward metastatic dissemination. In particular, we focused our attention on the main microenvironmental targets of the estrogen-IIGFs interplay, and we recapitulated relevant molecular nodes that orientate shared biological responses fostering the metastatic program. On the basis of available studies, we propose that a functional cross-talk between estrogens and IIGFs, by affecting the BC microenvironment, may contribute to the metastatic process and may be regarded as a novel target for combination therapies aimed at preventing the metastatic evolution.
... Whether promoting the recommitment of the progenitor-like-cells comprising the recurring metastatic tumors to differentiate warrants additional research. Importantly, there are other molecular mechanisms that were previously shown to promote the reversion of malignant breast cells, thus overriding their malignant phenotype, such as inhibition of either Intβ1 [127] or type 1 insulin-like growth factor receptor (IGF-IR) [128], or by promoting differentiation with either cAMP analogs or expression of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) [129]. It will be interesting to explore whether these mechanisms have committed CSCs/cancer progenitor cells to differentiate. ...
Distant recurrences occurring years after removal of the primary tumor arise from disseminated tumor cells (DTCs) that lie dormant (quiescent/asymptomatic) until they emerge to overt metastases. These quiescent DTCs are resistant to conventional treatments. Hence, to date there is no available treatment which targets dormant DTCs before they form overt metastases. Therefore, understanding the biology of dormant DTCs and the mechanisms of their reactivation is vital in our pursuit to develop therapies to prevent cancer from ever recurring.
This review will address the striking similarities between the biology of DTCs and the biology of cancer stem cells (CSCs) or CSC-like cells including cancer progenitor-like cells. These similarities are related to intrinsic mechanisms of survival and quiescence, and their cross-talk with mediators, produced in their surrounding niches that may support either dormancy or outgrowth. Unraveling these similarities may provide us with exciting opportunities to either mitigate the survival of residing dormant DTCs/CSCs or maintain them in a dormant state. Whether the stemness properties of CSCs/cancer progenitor-like cells already comprising the recurring tumor can be exploited in order to differentiate them, and thus promote their dormancy, will be explored as well. Overall, these emerging concepts may provide us with new opportunities to prevent lethal recurrences.
... IGF1, in combination with estrogen, is essential for normal mammary gland development, and this pathway is deregulated in the initiation and progression of breast cancer [2][3][4][5] . Many studies, including from our laboratory, have shown the ability of the IGF1 receptor (IGF1R) to promote mammary tumorigenesis and metastasis [6][7][8][9] . Additionally, we showed that when constitutively activated, IGF1R transformed mammary epithelial cells, increased migration and invasion, and induced epithelial to mesenchymal transition (EMT) via the NFkB pathway and upregulation of Snail 6,10 . ...
Purpose:
Insulin-like growth factor 1 (IGF1) signaling regulates breast cancer initiation and progression and associated cancer phenotypes. We previously identified E-cadherin (CDH1) as a repressor of IGF1 signaling and in this study examined how loss of E-cadherin affects IGF1R signaling and response to anti-IGF1R/insulin receptor (InsR) therapies in breast cancer.
Experimental design:
Breast cancer cell lines were used to assess how altered E-cadherin levels regulate IGF1R signaling and response to two anti-IGF1R/InsR therapies. In situ proximity ligation assay (PLA) was used to define interaction between IGF1R and E-cadherin. TCGA RNA-seq and RPPA data was used to compare IGF1R/InsR activation in estrogen receptor positive (ER+) invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) tumors. ER+ ILC cell lines and xenograft tumor explant cultures were used to evaluate efficacy to IGF1R pathway inhibition in combination with endocrine therapy.
Results:
Diminished functional E-cadherin increased both activation of IGF1R signaling and efficacy to anti-IGF1R/InsR therapies. PLA demonstrated a direct endogenous interaction between IGF1R and E-cadherin at points of cell-cell contact. Increased expression of IGF1 ligand and levels of IGF1R/InsR phosphorylation were observed in E-cadherin deficient ER+ILC compared to IDC tumors. IGF1R pathway inhibitors were effective in inhibiting growth in ER+ ILC cell lines and synergized with endocrine therapy and similarly IGF1R/InsR inhibition reduced proliferation in ILC tumor explant culture.
Conclusions:
We provide evidence that loss of E-cadherin hyperactivates the IGF1R pathway and increases sensitivity to IGF1R/InsR targeted therapy, thus identifying the IGF1R pathway as a potential novel target in E-cadherin deficient breast cancers.
... It has been shown that BMS-536924 inhibited the growth of MCF-7, AU565 and SUM149, which served as in vitro models of luminal, HER2 + and triple negative respectively, molecular subtypes of breast tumors [79]. In another study using the same molecule it was shown that BMS-536924 was able to inhibit growth of a wide range of BrCa cell lines (16 out of 23 tested) and block the migration of the triple negative MDA-MB-231 cells [83]. However clinical evidence using this molecule is yet lacking. ...
Despite the major discoveries occurred in oncology the recent years, breast malignancies remain one of the most common causes of cancer-related deaths for women in developed countries. Development of HER2-targeting drugs has been considered a breakthrough in anti-cancer approaches and alluded to the potential of targeting growth factors in breast cancer (BrCa) therapeutics. More than twenty-five years have passed since the Insulin-like Growth Factor-1 (IGF-1) system was initially recognized as a potential target candidate in BrCa therapy. To date, a growing body of studies have implicated the IGF-1 signaling with the BrCa biology. Despite the promising experimental evidence, the impression from clinical trials is rather disappointing. Several reasons may account for this and the last word regarding the efficacy of this system as a target candidate in BrCa therapeutics is probably not written yet. Herein, we provide the theoretical basis, as well as, a comprehensive overview of the current literature, regarding the different strategies targeting the various components of the IGF-1/IGF-1R axis in several pathophysiological aspects of BrCa, including the tumor micro-environment and cancer stemness. In addition, we review the rationale for targeting the IGF-1 system in the different BrCa molecular subtypes and in treatment resistant breast tumors with a focus on both the molecular mechanisms and on the clinical perspectives of such approaches in specific population subgroups. We also discuss the future challenges, as well as, the development of novel molecules and strategies targeting the system and suggest potential improvements in the field.
... Membranes were incubated with primary antibodies specific for MED15 (rabbit monoclonal; 1:200; clone 11566-1-AP; Proteintech), b-actin (mouse monoclonal; 1:5000; clone A1978; Sigma-Aldrich, St Louis, MO), or pSMAD3 (rabbit monoclonal; 1:1000; clone EP823Y; Abcam) overnight as previously described. 22,28,29 Then, membranes were incubated with horseradish peroxidaseeconjugated secondary antibodies at room temperature for 1 hour. Staining was detected using the ECL Plus chemiluminescence system (GE Healthcare Bio-Sciences, Pittsburgh, PA). ...
Head and neck squamous cell carcinoma (HNSCC) progression depends on various dysregulated pathways. Regulation of diverse pathways is mediated by the mediator complex. The mediator subunit MED15 is essential for transforming growth factor (TGF)-β signaling and involved in breast and prostate cancers. We investigated the implication of MED15 in HNSCC. IHC for MED15 was performed on 324 tissue samples, and TGF-β assessed the use of Ki-67 and pSMAD3 as markers. MED15 knockdown followed by proliferation and migration assays, as well as TGF-β1 treatment followed by MED15 analysis, was also performed. MED15 was overexpressed in 35% of primary tumors, 30% of lymph node metastases, and 70% of recurrences in contrast to no or low expression in benign tumors. MED15 overexpression in primary tumors from patients who developed recurrences was associated with higher mortality rates and occurred at highest frequency in oral cavity or oropharyngeal tumors. Furthermore, MED15 expression correlated between primary tumors and corresponding lymph node metastases. MED15 correlated with proliferation in tissues, and MED15 knockdown reduced proliferation and migration. We observed an association between MED15 and TGF-β activity in tissues because TGF-β activation led to increased MED15 expression and reduced pSMAD3 on MED15 knockdown. Taken together, our results implicate MED15 in HNSCC and hint that MED15 overexpression is a clonal event during HNSCC progression. MED15 may serve as a prognostic marker for recurrence and as a therapeutic target.
Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
... Wounding was induced by manually scratching the cell monolayer with a 200 ml pipette tip in growth media with 1% FCS. Effects of cellular proliferation were eliminated by pre-treatment of cells with 1 mM mitomycin C (Sigma-Aldrich) in the medium [19,20,21]. The wound closure was monitored 24 h later for MCF-7 cells, and 12 h later for MDA-MB-231 cells by phase-contrast microscopy using ZeissZen software (Zeiss). ...
The epidermal growth factor receptor (EGFR) is involved in the regulation of various cellular processes and dysregulation of its signalling plays a critical role in the etiology of a variety of malignancies like breast cancer. At the same time, elevated levels of urokinase (uPA), its receptor uPAR, and other components of the plasminogen activation system are found to be correlated with a poor prognosis in breast cancer. Interestingly, EGFR appears to participate in transducing the signal generated upon binding of uPA to uPAR. However, whether uPA signalling would thereby interfere with ligand-driven EGFR signalling was not described before. Therefore, it was the aim of the present study to investigate the combined effects of uPA and EGF in the low invasive and high invasive breast adenocarcinoma cell lines MCF-7 and MDA-MB-231, respectively. Simultaneous exposure of cells to both signals negatively affected ERK1/2 and AKT activation whereas positive effects on p38 and Src kinase phosphorylation were noted in both cell lines. Furthermore, uPA attenuated the mitogenic effect of EGF on cellular proliferation, invasion and motility in both MCF-7 and MDA-MB-231 cells. Experiments with the uPA amino terminal fragment (ATF) revealed that the negative effects of uPA were independent from its protease activity. Together, these data suggest that enhanced levels of uPA in breast cancer modulate the mitogenic effects of EGF and thus, this knowledge may help to better understand breast cancer pathogenesis as well as to develop new therapeutic options. © 2015 Wiley Periodicals, Inc.
