Apoptosis in transitional cell carcinoma of bladder and its relation to proliferation and expression of P53 and Bcl-2

Transitional cell carcinoma of bladder (TCC) is a relatively common cancer among men. Tumor progression is associated with expression or modulation of several gene products that control apoptosis and proliferation. Apoptosis is a negative growth regulatory mechanism in tumors. The aim of this study is to examine apoptosis and related regulatory molecular markers in a group of patients with TCC. Paraffin-embedded tissues from 49 patients with TCC were examined for the expression of bcl-2, p53 and Ki-67 by immunohistochemistry. Apoptosis was detected by TUNEL method. Correlation between apoptotic index ( AI), proliferation index ( PI) and bcl-2 and p53 expression with each other and with pathological grade was determined. Apoptosis was observed in 28.1% of TCC cases. The mean AI of all cases was 13.7 +/- 24. No correlation was found between apoptosis and differentiation status of carcinoma. Bcl-2 expression was weakly detected in only one sample. P53 expression was detected in 26 of cases with mean staining index of 102 +/- 96. A significant correlation between p53 and Ki-67 staining indices was observed ( r= 0.521, p= 0.001). Both p53 and Ki-67 expression showed a good association with the pathological grade ( p= 0.0001 and p= 0.004, respectively). None of the markers showed significant correlation with AI and no correlation was found between the ratio of AI to PI and other parameters either. In conclusion, the frequency of apoptosis in TCC of bladder appears not to be associated with tumor grade, and with bcl-2, p53 and Ki-67 expression.