Steroid sulfate sulfatase in human benign prostatic hyperplasia: Characterization and quantification of the enzyme in epithelium and stroma

Abstract Characteristics and activities of estrone sulfate (E1S) and dehydroepiandrosterone sulfate (DHAS) sulfatases were studied in epithelium and stroma of benign hyperplastic tissues from human prostates. Tissues were obtained by suprapubic prostatectomy, and epithelium and stroma were separated mechanically by standard techniques. The assay procedure comprised homogenization in Tris-buffer, incubation of the homogenate with [ 3 H]ElS or [ 3 H]DHAS, separation of free steroids from nonhydrolyzed steroid sulfates by extraction with ether, and their final quantification by LSC. The main results were: (1) The pH-optimum of the sulfatase was found at pH 7.0. (2) The highest specific sulfatase activity was found in the epithelium and was associated with its nuclear fraction. (3) Michaelis-Menten constants K m (μM) were 8.7 ± 1.4 (7) and 4.3 ± 0.8 (5), maximum velocity rates V max (nmol/h × mgDNA) were 47.4 ± 8.8 (7) and 8.4 ± 1.5 (5) for ElS and DHAS, respectively (means ± SEM ( n )). (4) The enzymatic cleavage of El-sulfate was competitively inhibited by DHA-sulfate and vice versa with inhibition constants K i (μM) of 4.0 ± 0.5 (2) for E1S and 2.7 ± 0.4 (2) for DHAS. On the basis of these findings, possible roles of steroid sulfate-sulfatases in forming precursors of active androgens and estrogens from the high amounts of E1S and DHAS in blood are discussed.