Objectives: To investigate expression of the reverse transcriptase component of human telomerase (hTERT) and of cyclin-dependent kinase inhibitor p57 (p57(kip2a)) in prostate neoplasms and evaluate the relationship between these proteins and the Gleason score.

Methods: hTERT and p57(kip2a) antibodies were studied by immunohistochemical methods in 70 prostate adenocarcinomas (33 high-grade and 37 low-grade carcinomas), 29 benign prostate hyperplasias, and 19 prostatic intraepithelial neoplasias (PIN). Only nuclear staining was evaluated with p57(kip2a) whereas both nuclear and nucleolar staining were evaluated with hTERT.

Results: Immunohistochemical histologic scores (HSCOREs) of hTERT were significantly higher in the PIN group than in the hyperplasia group (P = 0.03). hTERT HSCOREs were not significantly different between hyperplasias and carcinomas or between low and high-grade carcinomas. p57(kip2a) HSCOREs were significantly higher in hyperplasias than other groups, and in PINS than carcinomas, but did not differ significantly between low and high-grade carcinomas. A significant negative correlation was observed between hTERT and p57(kip2a) (P = 0.007) in the hyperplasia group. No such correlation was found in PINs and carcinomas.

Conclusions: This study suggests that p57(kip2a) is down-regulated in the malignant side of the spectrum of prostate carcinogenesis. Loss of p57(kip2a) control on hTERT might have an important role in the development of prostate cancer.