INHIBINS, ACTIVINS, AND FOLLISTATINS - EXPRESSION OF MESSENGER-RNAS AND CELLULAR-LOCALIZATION IN TISSUES FROM MEN WITH BENIGN PROSTATIC HYPERPLASIA

BACKGROUND. The transforming growth factor beta (TGF beta) superfamily of growth factors includes activins and inhibins, which have been sho wn to be present in the rat veneral prostate, and human prostate tumor cell lines, although their localization in benign prostatic hyperplas ia (BPH) tissue is currently unknown. METHODS. BPH tissues were obtain ed at surgery, and the mRNA expression for the inhibin alpha, beta(A), beta(B), subunits, the putative activin beta(C) subunit, the activin type II receptor (ActRII), and the activin binding protein, follistati n, was determined by reverse transcription polymerase chain reaction ( RT-PCR) and Southern blot analysis. Antibodies specific for alpha, bet a(A), beta(B), activin A, and follistatin were used to determine the l ocalization of these proteins in BPH tissue specimens. RESULTS. Southe rn blot analysis confirmed that mRNA for ActRII, beta(C), subunit, and follistatin was present in all biopsy samples assayed. However, alpha , beta(A), and beta(B) subunit mRNA expression was variable between pa tient samples. Immunohistochemistry demonstrated the predominant local ization of beta(A), beta(B), and activin A proteins to the epithelium of BPH tissues. No immunoreactivity for the inhibin alpha subunit was detected; follistatin immunoreactivity was localized to the fibroblast ic stroma. CONCLUSIONS. The compartmentalization of activin subunit pr oteins to the epithelium, and of follistatin to the stroma, suggests t hat a paracrine interaction occurs between the activin Ligands and fol listatin-binding proteins in BPH tissue. (C) 1998 Wiley-Liss, Inc.