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

GIANNA FIORELLI, ALESSANDRA DE BELLIS, ANTONELLA LONGO, ALESSANDRO NATALI, ALFIERO COSTANTINI and MARIO SERIO

Endocrinology Unit, Departments of Clinical Physiopathology (G.F., A.D., A.L., M.S.) and Urology (A.N., A.C.), University of Florence Florence, Italy

Address all correspondence and requests for reprints to: Dr. Gianna Fiorelli, Endocrinology Unit, Department of Clinical Physiopathology, University of Florence, Viale Morgagni 85, 50134 Florence, Italy.

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 [K_d, 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 < 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.

^* This work was supported by a Grant from the Associazione Italiana per la Ricerca sul Cancro and a Grant from the University of Florence.

Recipient of a fellowship from Sclavo (Siena, Italy).

Received July 25, 1988.