Expression of somatostatin receptor subtypes 2 and 4 in human benign prostatic hyperplasia and prostatic cancer

BACKGROUND. The presence of receptor subtypes for the inhibitory peptide somatostatin in prostatic tissue has been a controversial issue with conflicting reports. To elucidate whether prostatic epithelial cells express mRNA for somatostatin receptor (SSTR) subtype 2 and 4, we have investigated the localization of SSTR2 and SSTR4 transcripts in prostatic tissues by in situ hybridization. METHODS. Nonradioactive in situ hybridization was performed with specific fluorescein-labeled SSTR2 and SSTR4 riboprobes on consecutive sections of benign prostatic hyperplasia (BPH) and prostate cancer tissues. RESULTS. We report, for the first time, tissue localization of SSTR2 and SSTR4 mRNA in BPH and malignant cells of human prostate. Hybridization signals for SSTR4 mRNA transcripts were confined to the prostatic epithelium (12 of 16 BPH cases, and in 12 of 13 carcinoma cases), whereas SSTR2 transcripts were predominantly localized in the stromal compartment but also were detectable in epithelial cells in a significant number of specimens (11 of 17 BPH cases, and in 12 of 14 carcinoma cases). Furthermore, the staining intensity for SSTR2 and SSTR4 transcripts is stronger in malignant cells compared with adjacent BPH epithelium. CONCLUSION. The data presented suggest that the expression of SSTR2 and SSTR4 transcripts is up-regulated in malignant cells and that not only SSTR2 agonists, but also compounds targeting the SSTR4 subtype may have a potential role in the treatment of prostate cancer. (C) 2002 Wiley-Liss, Inc.