Expression of prostate stem cell antigen in high-grade prostatic intraepithelial neoplasia and prostate cancer.

Abstract Aims: To investigate prostate stem cell antigen (PSCA) and Ki-67 expression in normal-looking epithelium (NEp), atrophy, high-grade prostatic intraepithelial neoplasia (HGPIN) and prostatic adenocarcinoma (PCa). Methods and results: PSCA and Ki-67 were evaluated immunohistochemically in NEp, atrophy, HGPIN and PCa in 20 radical prostatectomies (RPs) and 20 cystoprostatectomies (CyPs). The proportions of PSCA positive cells and of cases with PSCA expression increased from NEp through atrophy and HGPIN to PCa. The differences between NEp and HGPIN and PCa and between atrophy and HGPIN and PCa were statistically significant for the away and adjacent locations, in both the RP and CyP groups. The differences between HGPIN and PCa were statistically significant in the RP group when it was away from PCa and in the CyP group when it was adjacent to and away from PCa. The values in the RPs were slightly greater than in the CyPs, the differences being not statistically significant. The proportions of Ki-67 positive nuclei increased from atrophy and NEp to HGPIN and PCa. The correlation between the proportion of Ki-67 positive nuclei and that of PSCA-positive cells was statistically significant. Conclusions: PSCA expression, deregulated in atrophy and HGPIN, is a marker associated with neoplastic transformation of prostate cells, both in RPs and CyPs.