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 a re mitogenic for prostatic cells and modulate the stroma-epithelium in teraction. IGF-binding proteins (IGFBPs) have an autocrine and/or para crine role in regulating the local actions of the IGFs. In this study, testosterone, dihydrotestosterone (DHT), 3 alpha androstanediol (3 al pha diol), IGF-I. IGF-II, IGFBP2, and IGFBP3 concentrations were evalu ated in human benign prostatic hyperplasia (BPH) tissue. Samples of pr ostate 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 a ssay, after acidification and chromatography. oil Sep-perk C18 Cartrid ges for ICF-I and IGF-II. Androgen concentrations, expressed ill ng/g tissue (mean +/- SE), were 0.51 +/- 0.05 for testosterone, 5.3 +/- 0.1 6 for DHT, and 1.1 +/- 0.07 for 3 alpha diol. IGF-I, IGF-II, IGFBP2, a nd 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 betwe en IGF-I, androgens, and IGFBPs was found. IGF-II was positively corre lated 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 modulat es the IGF system by increasing IGF-II without modifying IGFBPs. There fore, the stroma-epithelium interaction, which plays an important role in prostatic growth, may be regulated by, DHT through IGF-II. (C) 199 8 by Elsevier Science Inc.