Abstract 2734: Tumor-associated antigen c-terminal binding protein-2 is overexpressed in epithelial ovarian tumors

Abstract

Abstract OBJECTIVES: Investigation of the expression pattern and functional roles of tumor antigen CtBP-2 in ovarian cancer. BACKGROUND: Tumor-associated antigens may have mechanistic function in cancer development and serum antibodies that target the tumor-associated antigens may have value in early detection. Antibodies to C-terminal binding protein 2 (CtBP-2), a component of the Wnt signaling pathway and a transcriptional corepressor via interaction with histone deacetylases (HDACs), were identified in patient serum using an innovative reverse capture antibody array method. We investigated the expression and function of CtBP-2 in human ovarian cancer tissue and ovarian cancer cell lines. METHODS: CtBP-2 expression was studied in 105 paraffin-embedded ovarian tumors by standard immunohistochemistry (IHC). ANOVA was used to compare the mean IHC staining scores (area stained x intensity) between healthy and tumor samples. Functional assays were performed with human ovarian cancer cell lines SKOV3 and MCAS that stably integrated a CtBP2-targeting short-hairpin RNA (shRNA) construct via a Lentivirus vector. Protein expression was examined by western blotting. Cell proliferation in culture was evaluated by cell counting. Cell adhesion assays were performed using a CytoMatrix Screen kit from Millipore. Cell migration assays were performed using a Boyden chamber-based cell migration assay. B-catenin activity was measured using a TOPFLASH luciferase reporter assay. Cellular sensitivity to trichostatin A, a HDAC inhibitor, was measured using MTT assay. RESULTS: 83% of ovarian epithelial tumors stained positive with a mean score of 4.77 (borderline tumors) and 5.49 (invasive tumors) and showed a significant difference (p-value 50% and showed reduced proliferation rates. The knock-down cell lines also showed 40-80% reduction in adhesion to extracellular matrix proteins collagen I and collagen IV, 50-70% reduction in migration, suppressed B-catenin activity and enhanced sensitivity to trichostatin A. CONCLUSIONS: CtBP-2 is overexpressed in ovarian epithelial tumors and cancer cell lines. Ovarian cancer cell lines with suppressed CtBP-2 expression show a reduction in proliferation rate, cell adhesion and cell migration. The phenotype may be related to suppressed B-catenin activity. The knockdown cell lines are also more sensitive to HDAC inhibitor trichostatin A, suggesting that the expression of CtBP-2 might modulate cellular response to HDAC inhibitor in the clinical setting. 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 2734.