EXPRESSION OF MDM-2 AND P53 PROTEIN IN TRANSITIONAL-CELL CARCINOMA

Amplification of the mdm-2 gene and overexpression of the mdm-2 protei n might inactivate p53 function, and may have prognostic relevance. Th e present paper investigated the immunohistochemical overexpression of the mdm-2 and p53 proteins in 25 biopsy specimens of transitional cel l bladder carcinomas (10 pT1 and 15 pT2 or higher stages). Five cases (20%) showed strong mdm-2 protein immunoreactivity in more than 5% of the tumor cells; 14 cases (56%) showed p53 immunoreactivity in more th an 20% of the cells, and were considered as overexpressing p53 protein . Four of the five cases with strong mdm-2 immunoreactivity did not sh ow p53 overexpression, and 13 of the 14 cases with p53 overexpression did not show mdm-2 immunoreactivity. Our data are consistent with the hypothesis that p53 overaccumulation (and hence possible p53 gene muta tion) or mdm-2 overexpression (and hence possible mdm-2 gene amplifica tion) may mirror two different and possibly complementary gene alterat ions, which might finally interfere with the control of cell prolifera tion and apoptosis. In this perspective, evaluation of the combined md m-2/p53 protein phenotype in human bladder carcinomas could have progn ostic relevance and give us better prognostic information than evaluat ion of the p53 protein alone.