Clinical Signficance of p53, Proliferating Cell Nuclear Antigen and bcl-2 Expression in Bladder Transitional Cell Carcinoma

Abstract

To correlate the frequency of p53 mutations, bcl-2 expression and the proliferation status (proliferating cell nuclear antigen, PCNA) in patients with bladder cancer with cell proliferation, apoptosis and their clinico-pathologic findings. Paraffin-embedded sections from 39 superficial (T1G1-G3) and 23 invasive (T2-T4a G3 N0M0) primary transitional cell carcinomas (TCC) in the bladder were investigated immunohistochemically for p53, bcl-2 and PCNA. The median follow-up was 37 months; 24 had recurrences. The proliferation index (PI) was expressed as a percentage of the PCNA-positive cells in the tumor cells. Apoptosis was detected by terminal deoxy-nucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and the apoptotic index (AI) was expressed as a percentage of the TUNEL-positive tumor cells. p53 mutation was identified in 50 patients (80.6%). The mutation was most common in tumors grade 3 (91.3%) as compared to grade 2 (78.5%) and grade 1 (72.7%, P<0.05). Stage pT2 tumors had a higher frequency of p53 mutation (95.7%) as compared to pTa-1 tumors (74.3%, P<0.01). Only 14 tumors (22.5%) expressed bcl-2; grade 3 tumors expressed bcl-2 significantly more frequently (P<0.05); there was no correlation between bcl-2 and tumor stage. There was no interrelation between p53 mutation and bcl-2 expression (P>0.05). The PI ranged from 17.2% to 41.8% (median 22.4%) and the AI from 1.9% to 3.5% (median 2.9%) in bladder cancer. Statistical analyses revealed a close associations between PI, AI and tumor grade and stage of bladder cancer. p53 mutation correlates with invasion. p53 and PCNA overexpression may offer valuable additional prognostic information in bladder tumors. With the progression of the tumor grade, cell proliferation may be accompanied by frequent apoptosis in bladder cancer, but the PI increased much more than the AI.