Expression and localization of Bcl-2 related proteins in human ovarian cancers

Background: Interactions between Bcl-2 and its related proteins regulate cell death in a number of tissues including the ovary. Some Bcl-2-related proteins (Bcl-2, Bcl-xLong, Mcl-1, and Dad-1) function as cell death repressors, whereas others (Bax, Bcl-xShort, Bak, and Bad) facilitate apoptosis. Materials and Methods: Immunoblotting and immunohistochemistry using specific antisera were performed with a panel of human ovarian carcinomas and normal human ovaries. Results: All Bcl-2 related proteins were expressed in normal and malignant ovarian tissues. Higher levels of Bcl-2 versus Bcl-xLong were observed in normal ovary by immunoblotting, compared to a majority of cancer samples. Increased levels of death-inducing Bax were related to malignant transformation across all types of ovarian cancer included in this study. Conclusions: The results provide further evidence that a balance of expression among Bcl-2 family members may regulate ovarian cancer cell survival.