Abstract 3076: BVES, a novel adhesion molecule, acts as tumor modifier through modulation of tight-junction-associated signaling

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC BVES is novel adhesion protein that functions as a modulator of tight junction (TJ) formation with TJs level directly correlating with BVES expression. TJs, in addition to regulating paracellular passage of molecules, can also directly regulate Rho activity and transcriptional activation of cell cycle regulatory genes (ERBB2, PCNA, CDK4, and Cyclin-D1). Hence, alteration in BVES expression also modulates TJ associated signaling. Interestingly, overexpressing a dominant negative BVES induced human corneal epithelial cells to exhibit increased mesenchymal characteristics. Together, these observations led us to hypothesize that increasing BVES expression in carcinoma cells would induce an epithelial-like phenotype. To evaluate the function of BVES in carcinoma, a semi-adherent LIM2405 human colorectal cancer cell line was stably transfected with wild type BVES (WT-LIM2405) or empty vector (V-LIM2405) as control. Multiple stably transfected clonal isolates of LIM2405 overexpressing BVES exhibited increased epithelial features as evidenced by: i) uniform monolayer formation, ii) decreased vimentin and increased cytokeratin, Zo-1, and occludin expression, iii) decreased cellular motility (66% reduction, p<0.001), and iv) decreased colony number in soft-agar assays (53.5%, p<0.01). In addition, WT-LIM2405 cells progressively displayed reduced cellular proliferation, prolonged cell-doubling time (35%), and decreased S-phase and increased G1 fractions. This was more apparent with increasing confluence, suggesting that contact inhibition is restored with BVES expression. To evaluate the affect of BVES on tumor growth in vivo, V-LIM2405 and WT-LIM2405 cells were grown as orthotopic xenografts in athymic mice. WT-LIM2405 tumor growth was significantly attenuated (86%, p<0.001). Intra-tumoral proliferation rates were equivalent, however apoptosis was increased in WT-LIM2405 tumors (TUNEL positive cells/HPF, p=0.04). We next surveyed BVES expression in colorectal carcinoma. 80% of human CRCs samples exhibited at least a 40% reduction in BVES protein by immunoblotting. In addition, immunolocalization studies showed disorganized or absent BVES and ZO-1 staining only in carcinomatous regions. BVES expression is decrease not only in colorectal cancer (p=0.004), but also in breast (p=0.018) and thyroid carcinoma (p=0.20). Global expression analysis of 250 staged CRC samples compared with normal and adenoma colon specimens showed a decrease in BVES expression as early as carcinoma in situ (p<0.05). These findings indicate endogenous BVES expression is decrease in carcinoma and restoration of its’ expression induces an epithelial-like phenotype in colorectal cancer cells, thus implicating BVES as a tumor suppressor. Further investigation to determine the role of BVES in epithelial cancer biology is warranted and may lead to novel insight into targeted therapies. 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 3076.