MUC4 activates HER2 signalling and enhances the motility of human ovarian cancer cells

Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198-5870, USA.
British Journal of Cancer (Impact Factor: 4.82). 09/2008; 99(3):520-6. DOI: 10.1038/sj.bjc.6604517
Source: PubMed

ABSTRACT The mucin MUC4 is a high molecular weight transmembrane glycoprotein. It consists of a mucin-type subunit (MUC4alpha) and a transmembrane growth factor-like subunit (MUC4beta). The mucin MUC4 is overexpressed in many epithelial malignancies including ovarian cancer, suggesting a possible role in the pathogenesis of these cancers. In this study, we investigated the functional role of MUC4 in the human ovarian cancer cell line SKOV3. The mucin MUC4 was ectopically expressed by stable transfection, and its expression was examined by western blot and confocal microscopy analyses. The in vitro studies demonstrated an enhanced motility of MUC4-expressing SKOV3 cells compared with the vector-transfected cells. The mucin MUC4 expression was associated with apparent changes in actin organisation, leading to the formation of microspike, lammelopodia and filopodia-like cellular projections. An enhanced protein expression and activation of HER2, a receptor tyrosine kinase, was also seen, although no significant change was observed in HER-2 transcript levels in the MUC4-transfected SKOV3 cells. Reciprocal co-immunoprecipitation revealed an interaction of MUC4 with HER2. Further, the MUC4-overexpressing SKOV3 cells exhibited an increase in the phosphorylation of focal adhesion kinase (FAK), Akt and ERK, downstream effectors of HER2. Taken together, our findings demonstrate that MUC4 plays a role in ovarian cancer cell motility, in part, by altering actin arrangement and potentiating HER2 downstream signalling in these cells.

Download full-text


Available from: Ajay P Singh, Jul 06, 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ovarian cancer is a highly metastatic disease that is often characterized by widespread abdominal dissemination. A hallmark of ovarian cancer progression is the attachment of malignant cells to the mesothelium and the formation of invasive peritoneal implants. Therefore, delineating factors involved in cancer-peritoneal cell interaction is critical to improving patient survival, as it may lead to the discovery of novel therapeutic targets. As such, we aimed to identify proteins that participate in this interaction by comparing the secreted proteome of a co-culture model containing ovarian cancer (OVCAR-5) and mesothelial cells (LP-9), to their respective monoculture secretomes. In total, 49 proteins were differentially secreted during cancer and mesothelial cell contact. Relative mRNA expression of candidates was performed, which revealed a significant increase in MUC5AC gene expression in cancer cells cultured in three different co-culture models (OVCAR-5 and LP-9; BG-1 and LP-9; OV-90 and LP-9). An increased expression was also observed in LP-9 cells that were co-cultured with OVCAR-5 and OV-90 cancer cells. Further immunocytochemistry analysis also confirmed increased expression of MUC5AC in ovarian cancer and peritoneal co-cultures. Overall, our analysis uncovers novel molecular markers of peritoneal metastasis, which may have potential roles in regulating the progression of the disease.
    Journal of proteomics 04/2014; 103. DOI:10.1016/j.jprot.2014.03.042 · 3.93 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The HER2 transmembrane receptor is a well-characterized predictive marker for trastuzumab benefit and may be associated with decreased benefit from endocrine therapy use. Despite the clinical effectiveness of anti-HER2 agents, resistance represents a significant limiting factor. Focal adhesion kinase (FAK) plays an important role in HER2 signalling, mediating downstream Akt activation in addition to HER2 cross talk with other growth factor receptors. In this study, we have investigated the therapeutic potential of FAK in ER+/HER2+ breast cancer using the novel FAK-specific inhibitor, PF4554878 ('PF878'). FAK/HER2 signalling pathway activation was assessed in ER+/HER2- (MCF7, T47D) and ER+/HER2+ (BT474, MDAMB361) breast cancer cells in the presence or absence of PF878 and ± trastuzumab. The effects of PF878 on cell growth as a monotherapy and in combination with trastuzumab were assessed using MTT and coulter counting with isobologram analysis to determine synergy/additive effects. FAK activation (Y861 but not Y397) was highest in ER+/HER2+ cells that also demonstrated the greatest sensitivity to PF878. As a monotherapy, PF878 prevented heregulin-induced MDA361 cell migration but had no significant effect on cell growth. Treatment of ER+/HER2+ cells with PF878 and trastuzumab combined resulted in synergistic inhibition of cell proliferation. Underlying this was an abrogation of Akt activity and increased PARP cleavage, effects that were greatest in trastuzumab-refractory MDA361 cells. Collectively, these data support a role for FAK in ER+/HER2+ breast cancer where its targeting has the potential to improve trastuzumab response. This is particularly important in the context of ER+/HER2+, trastuzumab-refractory disease, where FAK inhibition may present an important strategy to restore trastuzumab sensitivity.
    Endocrine Related Cancer 07/2013; 20(5). DOI:10.1530/ERC-13-0019 · 4.91 Impact Factor
  • Source
    Pancreatic Cancer - Molecular Mechanism and Targets, 12/2011; , ISBN: 978-953-51-0410-0