Zinc and cadmium concentrations in whole tissue and in separated epithelium and stroma from human benign prostatic hypertrophic glands

Abstract

Prostate tissues from patients with benign prostatic hypertrophy were separated into epithelial and stromal components and the concentrations of zinc and cadmium were determined in these two fractions and in whole tissue by atomic absorption spectrophotometry. The concentrations of testosterone and Sa-dihydrotestosterone (Sa-DHT) were determined by radioimmunoassays. The concentration of zinc was found to be significantly greater (P < .001) in epithelial than in stromal preparations: 17.32 f 1.15 vs 7.29 f 0.53 pmol/g dry weight (SEM, n = 15). The concentrations of cadmium in epithelium, 9.55 f 1.31 nmollg dry weight (SEM, n = 15) and in stroma, 6.65 f 1.06 nmollg dry weight (SEM, n = 1% did not differ significantly. The concentrations of zinc and cadmium in whole tissues were 13.88 f 1.70 pmol/g dry weight and 8.85 k 1.53 nmol/g dry weight, respectively (SEM, n = 15).In epithelial preparations, cadmium and testosterone were inversely correlated, but no other correlations were noted between metal and androgen concentrations in whole tissue, stroma, or epithelium.The results of the present study indicate that zinc preferably resides in the epithelium of human prostatic tissue, particularly in BPH, although the stroma also contains significant amounts of this metal. Cadmium appears to be more evenly distributed between the epithelium and stroma of prostatic tissue and previous findings of high cadmium concentrations in hypertrophic and carcinomatous prostatic tissue were not confirmed.

Novel role of zinc in the regulation of prostate citrate metabolism and its implications in prostate cancer

“…Another factor which must be considered in analyzing the zinc content of prostate tissue is the histological distribution of zinc. The major site of zinc accumulation is associated with the glandular epithelium, which contains at least twice the zinc level of stromal tissue [7,8]. Thus the zinc levels of the glandular component of the prostate are actually greater than the values represented on the basis of total tissue content.…”

Steroid-binding Specificity of Human Sex Hormone-binding Globulin Is Influenced by Occupancy of a Zinc-binding Site

“…This suggested to us that coordination of a metal ion, such as Zn 2ϩ , in this position might influence the steroidbinding activity of SHBG. There are large amounts of zinc in the male reproductive tract, especially in locations where SHBG may play a role in regulating the activities of sexsteroids, such as the prostate (12,13). Therefore, we set out to determine if a metal-binding site exists in this region of human SHBG and if its occupancy by zinc influences the steroidbinding specificity of the protein.…”

“…Even if the zinc-dependent alteration in the steroid-binding specificity of human SHBG is not conserved in other mammalian species, it may serve some specialized function in human tissues where zinc concentrations are high and where SHBG is sequestered from the blood circulation, such as the prostate stroma (12,13). In this regard, benign prostatic hyperplasia in humans is associated with an excessive activity of sex steroids and/or an imbalance in their relative activities in the stromal compartment of the prostate (34).…”

Zinc Supplementation and Prostate Cancer

“…The central and transition zones account for 25% and 5% of the prostate volume, respectively. The normal peripheral zone of the prostate gland accumulates the highest concentrations of zinc in comparison to other soft tissues of the body (Kar & Chowdhury, 1966;Lahtonen, 1985). The ability to accumulate zinc in the peripheral zone is due to the presence of highly specialized secretory epithelial cells that is not found in the central zone of the prostate.…”