The Uptake of Testosterone and Zinc in Vitro by the Human Benign Hypertrophic Prostate

Abstract

SUMMARY The uptake of 65Zn and [1,2-3H]testosterone by minced tissue of human benign hypertrophic prostates and the subcellular distribution of radioactivity were examined. The nature of steroid and 65Zn binding by the cytosol (105000 g supernatant) fraction was investigated by gel filtration, ion-exchange chromatography and electrophoresis. It was found that steroid binding after incubation at 4°C was specific. One or two regions of steroid binding were observed after gel filtration of the cytosol using Sephadex G-200, depending upon incubation conditions. Binding of 65Zn was found in the low molecular weight peak after G-200 gel filtration. Equimolar CdCl2 and 65ZnCl2 were incubated with [1,2-3H]testosterone and minced tissue and the cytosol was subjected to gel filtration. Compared with control values, without CdCl2, reduction of 65Zn binding by about 50% occurred, while binding of 3H-labelled steroid was unaffected. Electrophoresis and ion-exchange chromatography showed that 65Zn and 3H-labelled steroid were bound to different proteins. A sample of the zinc-binding protein was prepared by ion-exchange chromatography and the homogeneity was checked by electrophoresis.

Zinc binding properties of human prostatic tissue, prostatic secretion and seminal fluid

“…In seminal plasma much of the zinc was bound to molecules of high and intermediate molecular weight (Table 1). (Reed & Stitch, 1973). Further purification led to the isolation of a histidine-rich zinc-binding protein, whose molecular weight was estimated at 32 000 (Heathcote & Washington, 1973 (Giles & Cousins, 1982).…”

Aconitase Activity, Citrate Oxidation, and Zinc Inhibition in Rat Ventral Prostate

“…However, factors such as the cellular distribution and specific protein binding of zinc must be considered rather than the total zinc content of tissue. General ly, nuclear and mitochondrial fractions con tain the highest levels of zinc in prostate [7,13,14], and specific protein binding of zinc appears to be significant [20]. There is vir tually no information regarding the affinity of aconitase for zinc in prostate.…”

Metal–androgen Interrelationships in Carcinoma and Hyperplasia of the Human Prostate

“…Differences in the concentration of zinc between normal and malignant prostatic tissue have also been reported (Schrodt, Hall & Whitmore, 1964;Gyorkey, Min, Huff & Gyorkey, 1967). More recent studies of prostatic subcellular fractions using isotopie zinc have revealed the presence of a zinc-binding protein in this tissue (Reed & Stitch, 1973). Recent reports have suggested that the concentration of free Zn2 + in prostatic cells may influence the further metabolism of testosterone to 5a-dihydrotestosterone (Grant, Min¬ guell, Taylor & Weiss, 1971).…”