Expression of p53 protein in prostate cancers of different histologic types.

Mutations and overexpression of p53 gene in prostate carcinoma have been found but their significance in the development and progression of cancer is so far unknown. We investigated the prevalence of abnormalities of p53 protein in a heterogeneous group of prostate carcinoma to verify whether acinar and non acinar carcinomas have a different expression of p53 protein. Paraffin sections of 45 prostate carcinomas (39 acinar, 3 ductal papillary, 1 transitional cell, 1 mucinous and 1 pure small cell) were examined for the expression of p53 protein using a panel of antibodies (monoclonal antibodies Pab 1801, D07 and polyclonal antibody CM1). No p53 expression was observed in any acinar carcinomas independent of grade and stage. For non acinar carcinomas only small cell and transitional cell carcinomas exhibited detectable amounts of p53 protein in tumour cell nuclei. The prevalence of p53 overexpression in prostate carcinoma is relatively low compared with that found in many other tumours. In the present study, the overexpression of p53 in a small cell carcinoma and in a transitional cell carcinoma suggests that the loss of suppressing role of p53 gene may be an important mechanism in the genesis and in the development of these uncommon tumours.