Gonadotropin-releasing hormone receptor expression in the human prostate

BACKGROUND. Inhibitory effects of gonadotropin-releasing hormone (GnRH) ana logs on prostate cancer cell proliferation, both in vivo and in vitro, indi cate the presence of specific binding sites for GnRH on prostate cancer cel ls. To investigate this issue further, we examined the expression of GnRH r eceptor (GnRH-R) mRNA and protein in human prostate biopsies as well as in other extrapituitary tissues. METHOD. The relative quantity of GnRH-R mRNA was determined by reverse tran scriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) in human prostate biopsies. Extrapituitary GnRH-R levels were determined b y a semiquantitative PCR reaction. RESULTS. Using PCR, a relatively high expression level of GnRH-R mRNA was f ound in prostate tumor tissue followed by normal prostate, thymus, and kidn ey expression levels. The levels showed by heart, brain, placenta, lung, li ver, skeletal muscle, pancreas, colon, ovary, small intestine, spleen, and testis were low but detectable, whereas peripheral blood leukocyte showed n o demonstrable product. GnRH-R immunoreactivity was localised in both lumin al and basal epithelial cells in benign and malignant prostate tissue, and GnRH-R were also observed in intraprostatic lymphocytes. The relative GnRH- R mRNA levels in prostate biopsies from 16 patients showed a wide range of individual differences, but these differences were not related to histologi cal grade. Castration therapy did not significantly influence GnRH-R mRNA e xpression in normal and malignant prostate tissue. CONCLUSION. These results suggest that epithelial cells and infiltrating ly mphocytes are targets for GnRH action in the human prostate. Comparative da ta show relatively high GnRH-R expression in human prostate tissue compared to other human tissues. (C) 2001 Wiley-Liss,Inc.