Immunohistochemical analysis of bcl-2 protein expression in renal cell carcinoma

Purpose: To investigate the incidence, extent, and distribution of bcl-2 pr otein expression in human renal cell carcinomas. Materials and Methods: Using immunohistochemical tissue staining techniques , bcl-2 protein expression was analyzed in archival nephrectomy specimens r emoved for renal cell carcinoma or trauma and in 3 renal cell carcinoma cel l lines. Results: Normal kidneys demonstrated bcl-2 immunopositivity primarily withi n the cytoplasm of distal tubule cells. Only rare and minor staining of the proximal tubular cells, thought to be the origin of renal cell carcinoma, was noted in histologically normal controls and areas adjacent to tumor. In contrast, bcl-2 protein expression was demonstrated in 70% of renal cell c arcinomas and in all 3 experimental cell lines. Conclusions: Bcl-2 is a proto-oncogene known to regulate apoptosis (program med cell death). Bcl-2 protein is overexpressed in the majority of renal ce ll carcinomas examined. Bcl-2 overexpression may have a role in tumorigenes is and may explain the relative resistance of renal cell carcinoma to chemo therapeutic agents and to radiation therapy.