Immunohistochemical expression of somatostatin receptor subtypes in prostate tissue from cystoprostatectomies with incidental prostate cancer.

OBJECTIVE: To examine immunohistochemically the expression of the five somatostatin receptors (SSTRs) in cystoprostatectomies (CyPs) with incidental prostate cancer. MATERIALS AND METHODS: The five SSTRs (SSTR1-5) were evaluated in 'normal-looking' epithelium (NEp), high-grade prostatic intraepithelial neoplasia (HGPIN) and pT2a Gleason score 6 adenocarcinoma in 20 CyP specimens with incidental prostate cancer and 20 radical prostatectomy (RP) specimens with clinically detected prostate cancer. RESULTS: For cytoplasm expression, the mean percentage of positive secretory cells with strong cytoplasmic staining increased from NEp to HGPIN and prostate cancer, being slightly lower in the CyP than in the RP specimens. Both in the CyP and RP specimens SSTR4 was found in the highest percentage of cells. There was membrane staining in the secretory cells for SSTR3 and SSTR4. There was nuclear staining in the secretory cells for SSTR4 and SSTR5. For SSTR1 and SSTR3 the mean proportions of positive basal cells were higher than for the other three subtypes, and greater in NEp than in HGPIN. There were positive smooth muscle and endothelial cells for all five SSTR subtypes, the highest proportions being SSTR1 and the lowest SSTR5. CONCLUSIONS: This immunohistochemical study expands our knowledge of the expression and localization of SSTRs in the various tissue components in the prostate with incidental cancer, compared with clinically detected cancer. Such information might be useful in developing further non-invasive strategies for the prevention and treatment of pre-neoplastic and neoplastic lesions of the prostate.