PARENT SESSION

(T218) ADENOVIRUS-DIRECTED OVEREXPRESSION OF PROHIBITIN MEDIATES STAUROSPORINE-INDUCED APOPTOSIS IN OVARIAN CANCER CELLS.

Gregory-Bass, Rosalind¹, Xu, Wei¹, Stiles, Jonathan¹, Zeleznik, Anthony², Tsang, Benjamin³, Thompson, Winston¹, ¹ Morehouse School of Medicine, Atlanta, GA² University of Pittsburgh, Pittsburgh, PA³ University of Ottawa, Ottawa, Canada

ABSTRACT- Prohibitin-1 is a highly conserved protein implicated as an important regulator in cell survival. Although prohibitin has recently been demonstrated to suppress apoptosis in mammalian cells, its expression and role in human ovarian epithelial cancer is unknown. In this study we used normal and pathologic ovarian cancer tissues, Rb-deficient OVCAR-8 human ovarian cancer cell line, and adenoviral prohibitin-GFP to examine the role of prohibitin-1 in the regulation of apoptosis. Immunohistochemical localization of prohibitin-1 in normal and human ovarian surface epithelial tumors demonstrated the presence of prohibitin-1 with its expression being highest in non-proliferative cells. Treatment of OVCAR-8 cells with staurosporine, an apoptotic agent, consistently increased prohibitin content and induced apoptosis in a time- and concentration-dependent manner. Infection of the OVCAR-8 cells with a prohibitin adenoviral construct resulted in overexpression of prohibitin that markedly attenuated the ability of staurosporine to induce apoptosis via the intrinsic apoptotic pathway. Compared to controls, flow cytometric cell cycle analysis revealed that overexpression of prohibitin inhibits most cells from progressing to S-phase of the cell cycle. These studies suggest that prohibitin mediates apoptosis in human ovarian cancer cells and may be a point of regulation in the induction of apoptosis.

KEY WORDS: prohibitin, ovarian cancer, apoptosis, adenovirus