Abstract 2038: The role of epithelial-mesenchymal transition in ovarian cancer

Abstract

Abstract Epithelial ovarian cancer (EOC) is one of the leading causes of death due to malignant disease in women. Due to its asymptomatic nature, 80% of patients are diagnosed at late stages, when the disease has metastasized and 5 year survival rates are then around 30%. Typically late stage EOC rapidly develops resistance to chemotherapy. Recently, attention has focused on a possible involvement of EMT: epithelial-mesenchymal-transition- in the development of resistance to chemotherapy drugs. EMT refers to a change in cell morphology with the loss of the apical-basal polarity of a cell, the loss of cell-cell junctions and the gain of a spindle-like shape with migratory and invasive properties. Our work sets out to understand the role of EMT in EOC focusing on its contribution to the development of resistance towards carboplatin and paclitaxel. Firstly, an in-vitro model of EMT was developed with OVCAR-3 EOC cells, using a cocktail of 20ng/ml EGF, 50ng/ml IL-6 and 10ng/ml TGF-β. Western blot results showed significantly increased expression of slug and vimentin with decreased E-cadherin expression in the in-vitro derived EMT model compared to the control untreated cells. In addition, using established drug resistant cell lines of OVCAR-3, PEO1, CaOV3 and SKOV-3 the EMT signature was compared with that of the corresponding parental line. Western blot examination indicated decreased E-cadherin expression (P>0.05) and significantly increased slug and vimentin expression (P<0.05) in the resistant cell lines, similar to the cytokine-treated model of EMT induction. In order to observe the effect of drug resistance on migratory properties, OVCAR-3 (paclitaxel-sensitive and resistant) and PEO1 (carboplatin-sensitive and resistant) were used in scratch/wound healing assays. Drug treatment was carried out and wound closure was measured with CellProfiler after 72 hours. A significantly increased migratory capacity (wound closure) was observed in drug resistant cells in the absence and presence of chemotherapy drugs, when compared with parental cells (P<0.05). In order to clarify any possible role for slug in the induction of drug resistance, we carried out SiRNA silencing of OVCAR-3 cells. Silenced cells (alongside scramble control) were subjected to drug treatment for 48 hours and were then assessed for apoptosis using the annexin assay (FITC and PI). On silencing the slug gene, a significant resensitization to carboplatin could be observed compared to control cells (P<0.05). Further work includes analyses of the panel of drug sensitive and drug resistant (carboplatin and paclitaxel) EOC cell lines to identify other gene changes associated with EMT, using PCR array approaches. This work will help with the identity of candidate biomarkers of clinical drug resistance for EOC patients. Citation Format: Hasanthi Assalaarachchi, Helen M. Coley. The role of epithelial-mesenchymal transition in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2038.