Insulin-like growth factor-I and -II in human benign prostatic hyperplasia: Relationship with binding proteins 2 and 3 and androgens

In prostatic tissue, androgen action may be mediated by growth factors such as insulin-life growth factor-I (IGF-I) and II (IGF-II), which are mitogenic for prostatic cells and modulate the stroma-epithelium interaction. IGF-binding proteins (IGFBPs) have an autocrine and/or paracrine role in regulating the local actions of the IGFs. In this study, testosterone, dihydrotestosterone (DHT), 3 alpha androstanediol (3 alpha diol), IGF-I. IGF-II, IGFBP2, and IGFBP3 concentrations were evaluated in human benign prostatic hyperplasia (BPH) tissue. Samples of prostate tissue were removed by suprapubic prostatectomy from twelve BPH patients. Androgen tissue levels were determined by radioimmunoassay!, after purification on celite microcolumns. IGF-I. IGFBP2, and IGFBP3 were measured by radioimmunoassay, and IGF-II by immunoradio metric assay, after acidification and chromatography. oil Sep-perk C18 Cartridges for ICF-I and IGF-II. Androgen concentrations, expressed ill ng/g tissue (mean +/- SE), were 0.51 +/- 0.05 for testosterone, 5.3 +/- 0.16 for DHT, and 1.1 +/- 0.07 for 3 alpha diol. IGF-I, IGF-II, IGFBP2, and IGFBP3 levels were 24 +/- 3.7 121 +/- 14 ng/g tissue and 0.44 +/- 0.05 and 1.2 +/- 0.17 mu g/g tissue, respectively, No correlation between IGF-I, androgens, and IGFBPs was found. IGF-II was positively correlated with DHT (r = 0.78; p = 0.003) and 3 alpha diol (r = 0.66; p = 0.021) bur not with IGFBPs. These datn suggest that in BPH, DHT modulates the IGF system by increasing IGF-II without modifying IGFBPs. Therefore, the stroma-epithelium interaction, which plays an important role in prostatic growth, may be regulated by, DHT through IGF-II. (C) 1998 by Elsevier Science Inc.