Relations between immunologically different p53 forms, p21(WAF1) and PCNA expression in ovarian carcinomas

The role of tumor suppressor p21WAF1 expression in epithelial ovarian cancer has not been definitely explained and the clarification of mutual p53 and p21WAF1 relations considering proliferative activity seems to be very important for understanding of a functional link between p53 and cell-cycle control. Therefore the expression of p53 and p21WAF1 was assessed immunohistochemically in a series of 50 ovarian carcinomas considering clinicopathological variables. The reactivity of three anti-p53 monoclonal antibodies (DO-7, PAb240, PAb1620) recognizing immunologically distinct forms of p53 were analysed in relation to p21WAF1 level in individual patients. p21WAF1 was expressed in 24 (48%) of all cases. The detection of p53 protein was related to the antibody applied and DO-7 antibody appears to be better than both PAb240 and PAb1620. However, independently of antibody used significant inter- and intratumoral heterogeneity in p53 and p21WAF1 expression was revealed. The identification of different p53/p21WAF1 phenotypes reflect the complex and multiple relations between these two cell-cycle regulators indicating that in ovarian carcinomas p21WAF1 activation may be both p53-dependent and p53-independent. High cell proliferation was usually accompanied by undetectable or weak p21WAF1 staining. There was no significant correlation between p53 and p21WAF1 expression and histology, stage and grade of ovarian carcinomas (p>0.05).