17β-Hydroxysteroid dehydrogenase in the human prostate. Properties and distribution between epithelium and stroma in benign hyperplastic tissue

Abstract In order to delineate differences in the mechanism of androgen action in epithelium (E) and stroma (S) of the human prostate, we studied the 17β-hydroxysteroid dehydrogenase (17β-HSDH) in these tissues of benign prostatic hyperplasia (BPH). Tissue was obtained by suprapubic prostatectomy. E and S were separated; samples were homogenized in buffer and incubated with [ 3 H] steroids (4-androstenedione (Ae), estrone (E 1 ), or dehydroepiandrosterone (DHEA)) and NADH (4.2 mmol/1) as cosubstrate for 60 min at 37°C. Separation and quantification of the metabolites were performed by TLC and LSC, respectively. The main results were: (1) Following incubation with DHEA and E 1 only the metabolites 5-androstene-3β,17β-diol and estradiol, respectively, were found. Following incubation with Ae, testosterone, 5α-dihydrotestosterone and 5α-androstane-3α-(β),17β-diol were detected as metabolites (the sum of these metabolites were used for calculations). (2) The Michaelis constants were identical in E and S (mean ± SEM ( n ), μmol/l, Ae 6.92 ± 1.01 [9], E 1 7.84 ± 0.69 [9], DHEA 3.73 ± 0.38 [14]). (3) The maximum velocity rate for the three substrates in E was 5–10-fold that in S ( P at least