title: Transforming growth factor-beta induces growth inhibition and IGF-binding protein-3 production in prostatic stromal cells: abnormalities in cells cultured from benign prostatic hyperplasia tissues.
abstract: The IGF axis has been implicated in the pathogenesis of benign prostatic hyperplasia (BPH) via the paracrine action of IGFs and IGF-binding proteins (IGFBPs). In this study, we examined the regulation of cell growth and IGFBP-3 secretion by transforming growth factor-beta (TGF-beta) in prostatic stromal cell (PC-S) cultures from histologically normal tissues and tissues from BPH. PC-S cultures were treated with varying doses of TGF-beta1. Forty-eight hour conditioned media (CM) from these cultures were subjected to Western immunoblotting and ligand blotting for detection and quantification of IGFBPs. IGFBPs-2, -3 and -4 were detected in the CM from normal PC-S cultures. In CM from BPH PC-S, IGFBP-3 levels were 2-fold lower at baseline than in the normal PC-S CM, in addition to the differences in IGFBPs-2 and -5 which we have previously reported. In response to TGF-beta1, a 15-fold increase in the levels of IGFBP-3 was observed in normal PC-S CM, while a mere 2-fold increase was observed in BPH PC-S CM (P<0.001). These findings were confirmed by specific immunoblotting and immunocytochemistry. IGFBP-3 mRNA levels detected by Northern blotting of total RNA extracted from similar cultures showed the induction of IGFBP-3 expression by TGF-beta1 in normal PC-S and its lack of induction in BPH PC-S. Cell growth inhibition in response to TGF-beta1 correlated with the IGFBP-3 concentrations found in CM. Normal PC-S showed a 60% decrease in cell number after 10 days in media with 1 ng/ml TGF-beta1, compared with the untreated control. The decrease in proliferation observed in comparably treated BPH cells was only 20% (P<0.001). In conclusion, BPH PC-S had a reduced IGFBP-3 response to TGF-beta1 and demonstrated decreased TGF-beta1-induced growth inhibition relative to normal PC-S. We hypothesize that in normal PC-S, TGF-beta exerts its anti-proliferative effects by stimulating the production of IGFBP-3, which acts as an inhibitory factor, either by inhibiting IGFs or directly by interacting with cells, and that this process is altered in BPH PC-S.
authors.affiliation: Pediatric Endocrinology, UCLA, Los Angeles, California 90095, USA. hassy@mednet.ucla.edu
authors.forename: P
authors.initials: P
authors.lastname: Cohen
authors.forename: S E
authors.initials: SE
authors.lastname: Nunn
authors.forename: D M
authors.initials: DM
authors.lastname: Peehl
mesh_terms: D015153:Blotting, Western; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism*; D008297:Male; D011470:Prostatic Hyperplasia / Q000378:metabolism / Q000473:pathology*; D017154:Stromal Cells / Q000166:cytology / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D016212:Transforming Growth Factor beta