Expression of bcl-2, p53, and p21 in benign and malignant prostatic tissue before and after radiation therapy

Abnormalities in genes of the apoptotic pathway might contribute to survival in prostatic cancer (PCa) cells after radiation therapy (RT). We investigated the immunohistochemical expression of the products of the p53, p21WAF1, and bcl-2 genes in pre-RT and post-RT biopsy specimens from 38 patients with locally advanced PCa. All of the 38 patients underwent a uniform protocol of RT with or without neoadjuvant hormonal therapy. Immunohistochemical staining for expression of the products of the p53, p21WAF1, and bcl-2 genes was performed on material from pre-RT and post-RT specimens. Sufficient tissue for analysis was available from 25 of the pre-RT and 38 of the post-RT biopsy specimens. In benign prostatic epithelium, RT resulted in expression of p53 (2 [8%] of 25 pre-RT specimens vs. 15 [71%] of 21 post-RT specimens; P < .001) and increased expression of bcl-2 (1 [5%] of 18 pre-RT vs. 18 [86%] of 21 post-RT; P < .001). There was no change in the expression of p21WAF1 (1 [4.5%] of 22 pre-RT vs. 4 [17%] of 23 post-RT; P = NS). Post-RT specimens were positive for PCa in 24 (63%) of 38 cases. In the PCa tissue, p53 expression was seen in 10 (42%) of 24 pre-RT and 12 (63%) of 19 post-RT samples (P = NS). A significant upregulation of p53 was seen in the subgroup of patients who did not receive neoadjuvant hormonal therapy (9 [82%] of 11 vs. 3 [38%] of 8; P = .05). No significant change in p21WAF1 (5 [21%] of 24 vs. 5 [33%] of 15; P = NS), or bcl-2 (4 [18%] of 22 vs. 3 [21%] of 14; P = NS) expression was detected. There was no significant correlation between immunohistochemical expression of apoptosis-related markers and treatment failure. We concluded that RT induced upregulation of the bcl-2 and p53 gene products in benign prostatic tissue and that this likely reflected a protective mechanism in genetically unaltered epithelium. Increased p53 expression in PCa was only seen in patients without neoadjuvant hormonal treatment, indicating that the cancer cells with abnormal p53 were at least partially protected from RT-induced cell death.