A comparison of p21 and p27 immunoexpression in benign glands, prostatic intraepithelial neoplasia and prostate adenocarcinoma

Abstract

To assess the immunoexpression of p21 and p27 proteins in consecutive areas of benign glands, prostatic intraepithelial neoplasia (PIN) and prostate adenocarcinoma. Tissue from 91 patients who had a radical prostatectomy was assessed by immunohistochemistry to evaluate the expression of p21 and p27 in adjacent areas of benign glands, PIN and prostate adenocarcinoma. The results were correlated with various clinicopathological variables, e.g. age, total prostate-specific antigen level, tumour stage, Gleason score, surgical margin involvement, extraprostatic extension, seminal vesicle invasion, and perineural invasion. The p27 score in PIN was lower than that in benign glands (P = 0.04) but there was no significant difference between the scores for PIN and tumour. By contrast, p21 expression was almost undetectable in benign glands, although there was substantially more in PIN and tumour (P < 0.01). Some patients had no expression of p21 in tumour tissue, and had lower p21 scores in benign glands and PIN areas (P < 0.05). Interestingly, these patients had a lower frequency of negative prognostic variables. The tumour p21 score was higher in patients with extraprostatic extension (P = 0.045) and tumour p27 expression was inversely correlated with seminal vesicle invasion (P = 0.028). Tumour and PIN p27 expression appeared to decrease with advancing age (P = 0.008 and 0.012, respectively). Higher p21 and lower p27 expression is correlated with adverse prognostic factors. The decline in p27 with advancing age in tumour and PIN areas may be a possible explanation of the greater frequency of prostate adenocarcinoma in older men. A p21-negative tumour subgroup with a lower frequency of adverse prognostic factors was identified, which needs to be further explored.