Steroid receptor content in cytosol from normal and hyperplastic human prostates.

ABSTRACT

Analyses of steroid hormone receptors were performed using a dextran-coated charcoal technique in cytosolic preparations from 40 cases of benign prostatic hyperplasia (BPH) and 10 normal human prostates. Binding data were calculated according to Scathchard. In all BPH specimens, receptors for the synthetic androgen methyltrienolone (MT) were found (mean maximum number of binding sites, 566 fmol/mg DNA; mean Kd, 0.61 nM), and 25 of 28 samples contained progestin [17 alpha, 21-dimethyl-19-nor-4.8-pregnadiene-3,20-dione (R5020)] receptors (mean maximum number of binding sites, 420 fmol/mg DNA; mean Kd, 0.39 nM). No specimen contained glucocorticoid [dexamethasone (9 alpha-fluoro-16 alpha-methyl-11 beta, 17 alpha, 21-trihydroxy-1,4-pregnadiene-3,20-dione); n = 16] or estrogen [17 beta-estradiol or 11 beta-methoxy-17 alpha-ethynyl-17 beta-estradiol (R2858); n = 26] receptors. No correlations were found between receptor content and age of the patients, weight of adenomas, or percentage of different cell types within the specimens. MT receptors were found in all normal prostates, while 5 of the specimens lacked progestin receptors. Estrogen receptors were found in 3 of the normal prostates, whereas none contained glucocorticoid receptors. The ligand specificity of the MT receptor in a normal prostate with minor amounts of progestin receptors was typical of an androgen receptor, and the ligand specificity of the R5020 receptor in a BPH specimen was typical of a progestin receptor. MT and R5020 had approximately the same affinity for the progestin receptor, whereas the relative binding affinity of R5020 for the androgen receptor was below 0.02 compared to that of MT. The androgen receptor was found to be more stable during repeated freezing and thawing than the progestin receptor.