Epidermal Growth Factor Receptors in Human Hyperplastic Prostate Tissue and Their Modulation by Chronic Treatment With a Gonadotropin-Releasing Hormone Analog*

Abstract

We characterized the epidermal growth factor (EGF) receptor in the membrane fraction of prostatic tissue from men with benign prostatic hyperplasia (BPH). The maximum specific binding of [125I]EGF to the BPH membrane fraction was achieved after 30-min incubation at 35 C. Analysis of the binding data revealed two classes of binding sites, one of high affinity [Kd, 2.5 +/- 0.5 (+/- SE) x 10(-11) mol/L] and one of lower affinity (2.2 +/- 0.3 x 10(-9) mol/L). [125I]EGF binding was inhibited by excess EGF, but not by insulin, proinsulin, fibroblast growth factor, or insulin-like growth factors I and II. In prostatic tissue of men with BPH treated for 3 months with the GnRH agonist analog Goserelin (Zoladex, depot formulation), the binding capacities of both sites were significantly higher than those of BPH tissue from untreated men (P less than 0.001). These results demonstrate that prostatic tissue from men with BPH contains two classes of specific binding sites for EGF, and their levels are modulated by chronic GnRH agonists treatment.