Bcl-2 and p53 protein expression, apoptosis, and p53 mutation in human epithelial ovarian cancers

Bcl-2 and p53 gene products have been both linked to cell death by apoptosi s. In the present study, we examined the relationship of Bcl-2 and p53 prot ein expression,p53 mutation and apoptosis in normal human ovaries and diffe rent types of human ovarian epithelial tumors by immunohistochemical locali zation, in situ terminal transferase-mediated dUTP nick end labeling and po lymerase chain reaction-single strand conformation polymorphism. It was fou nd that Bcl-2 expressed strongly in the surface epithelium of normal ovarie s and benign and borderline ovarian tumors but weakly in the malignant tumo rs. On the contrary, strong protein expression of p53 was found in 54% (25/ 46) of the malignant epithelial tumors examined but similar expression of p 53 was not observed in borderline and benign tumors and normal ovarian surf ace epithelium, A significant inverse correlation between Bcl-2 and p53 exp ression was found in the malignant ovarian tumors examined. p53 gene mutati on at exons 5-11 was however not a pre-requisite for p53 expression in both borderline and malignant tumors. Apoptotic activities, as reflected by apo ptotic indices, were low in normal ovarian surface epithelium and. benign t umors but were increased in borderline and malignant tumors, with the highe st average apoptotic index found in grade III malignant tumors. Statistical analyses showed a positive correlation between apoptosis and p53 expressio n, but similar correlation was not found between apoptosis and Bcl-2 expres sion. Our results also indicate that although expression of Bcl-2 is import ant during ovarian carcinogenesis, the Bcl-2 protein may have other roles t o play apart from being a modulator of apoptosis in human ovarian epithelia l cancers.