Abstract 4780: c-FLIP knockdown increases apoptosis in cervical cancer cell lines

Abstract

Abstract Cervical Uterine cancer is a leading cause of cancer deaths in women worldwide. Its natural history begins gradually from low-grade and high-grades squamous intraepithelial lesions to an invasive disease. Decades of studies have confirmed a directly association between persistent high-risk Human Papillomavirus (HPV) infections and cervical cancer. However, high-risk HPV infections are not sufficient to induce cellular transformation and tumor occurrence. The cellular FLICE-like inhibitory protein (c-FLIP) has been founded overexpressed in several cancers and could be associated with cervical carcinogenesis. c-FLIP is a catalytically inactive caspase-8/-10 homologue, and when is overexpressed has the ability to inhibit the extrinsic pathway of apoptosis. Aim: To characterize c-FLIP participation in cervical carcinogenesis.Materials and Methods: Four cell lines were used in this study: ECT1 E6/E7 (squamous normal cervical epithelial), SiHa (cervical carcinoma containing an integrated HPV 16 genome), C-4I (cervical carcinoma containing an integrated HPV 18 genome) and C-33A (cervical carcinoma without HPV). c-FLIP expression in cell lines was determined by real time PCR and western blot. c-FLIP expression was transiently downregulated by siRNA directed against c-FLIP mRNA and the silencing effects on cell viability and apoptosis were analysed, by comparing with a control negative siRNA-transfected cells.Results: c-FLIP was found to be overexpressed in SiHa and C-4I cell lines and repressed in C-33A cell line. Only the long variant of c-FLIP was found in cervical cancer cell lines. Transient knockdown of c-FLIP resulted in significant reduction in cell viability (p< 0.001), compared with negative control siRNA-transfected cells. Knockdown cells lines exhibited an increased apoptotic rate in comparison with controls (p<0,001). Conclusions: The long variant of c-FLIP is overexpressed in cervical cancer cell lines with integrated genome of a high-risk HPV. Furthermore, the siRNA-mediated downregulation of c-FLIP expression induces apoptosis and decreases cell viability in cervical cancer cell lines. Therefore, this protein could be a potential therapeutic target in cervical cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4780. doi:10.1158/1538-7445.AM2011-4780