Abstract 1194: The splicing isoform osteopontin-c contributes to ovarian cancer progression

Abstract Introduction: Osteopontin (OPN) is a secreted glycophosphoprotein that is involved in tumorigenesis and metastasis in many solid tumors. Alternative splicing of OPN mRNA generates 3 known species and proteins, OPNa, OPNb and OPNc. Objective and Methodology: The aim of the present work was to investigate the expression profiling and the functional roles of OPN isoforms in ovarian carcinoma. Here we investigate the expression of each OPN isoform in ovarian cell lines and ovarian tissues, by quantitative real-time PCR using OPN splice variants specific primer pairs. We then investigated the roles of each one of these isoforms by using in vitro and in vivo models. Cell proliferation, migration and anchorage independent cell growth analysis were performed using OvCAr-3 cells overexpressing OPNa, OPNb or OPNc isoforms. Tumor formation was evaluated in athymic nude mice inoculated with OvCar3 cells overexpressing each oisoform as compared to empty vector controls. Results: We show that OPNa and OPNb are expressed in all ovarian tissues analyzed. However, the isoform OPNc is selectively present in malignant and borderline ovarian tumors and malignant tumor cell lines, but not in benign and normal ovarian tissues. Cell proliferation, migration, anchorage-independent growth and tumor growth in vivo are dramatically increased in OvCar-3 cells overexpressing OPNc. In contrast, OPNa and OPNb do not present these same pro-tumorigenic properties. Conclusions: These results together provide compelling evidence that OPNc plays important roles in ovarian cancer progression. Firstly, OPNc is specifically expressed in borderline and malignant ovarian tumors. Secondly, OPNc expression facilitates tumor progression towards an aggressive phenotype. Targeting OPNc in ovarian cancer has potential as a novel therapeutic strategy. Financial Support: CNPq, CAPES, FAPERJ, Swiss Bridge Foundation, FAF/MS Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1194.