Inhibition of steroid-protein interactions by dicyclohexane derivatives.

Sixteen dicyclohexane derivatives including the parent compound d,1-3,4-bis (4-oxocyclohexyl)-hexane (PRDX) have been synthesized and studied for putative interference with androgen binding to transport proteins, metabolizing enzymes, and receptors from rat tissues. Several of these analogues inhibited competitively the binding of dihydrotestosterone to ABP, the epididymal androgen transport protein. One compound had an affinity for ABP as high as Kd = 70 nM. Some dicyclohexanes also inhibited the aromatase enzyme which catalyses conversion of androgens into estrogens, as well as the NADPH-dependent, particulate form of 3 alpha(beta)-hydroxysteroid dehydrogenase, the enzyme that converts dihydrotestosterone into 5 alpha-androstanediol. For both enzymes the inhibition potency Ki of PRDX was about equal to the Km of the substrate. All of these interactions were specific in that they were modulated by single substitutions on the dicyclohexane molecule and they did not occur with other steroid binding proteins such as 5 alpha-reductase and the intracellular androgen receptor. A conformational study showed that dicyclohexanes can assume a 'steroidoid' conformation that differs from the crystal structure and which could account for the specific interactions with the steroid binding sites described here.

Conversion of sterols and triterpenes by mycobacteria. II. Transformation of 7-oxygenated sterols into androstane derivatives via a 7-deoxygenation.

The bioconversion of 7-oxygenated sterols by Mycobacterium aurum was studied in a preliminary investigation of the microbial conversion of wool wax. 7-Oxocholesterol was found to be transformed mainly into 3,17-dioxygenated androstane derivatives. 7 xi-Hydroxylated sterols were formed in an initial reduction step, and the C-7 hydroxyl group was then eliminated in a dehydration reaction. This was thought to take place during the isomerisation of cholest-4-en-3-one to cholest-5-en-3-one. Deuterium labelling experiments showed that this elimination proceeded faster for the C-7 alpha isomer, although it was not stereospecific. The C-7 alpha and C-7 beta-hydroxy isomers were weakly interconverted via the 7-oxo derivatives. Cholest-4-en-3-one, cholest-1,4-dien-3-one and cholest-4,6-dien-3-one all lost their side chains following a hydrogenation/dehydrogenation reaction. The resulting 3,17-dioxoandrostene or 3,17-androstadiene derivatives were mainly hydrogenated into 5 alpha-androstane-3,17-dione and 5 alpha-androstane-3 beta-ol-17-one. Elimination of the 3 beta-hydroxyl groups giving cholesta-3,5-dien-7-one, and subsequent microbial degradation of the side chain was not observed to any significant extent. The convergence of the bioconversion pathways of cholesterol and the 7-oxygenated cholesterols enabled crude, partially auto-oxidised cholesterol to be used as a substrate for the production of 3,17-dioxygenated androstane derivatives by M. aurum.

Conversion of testosterone and androstenedione to 5 beta-androstanes by adult male hamster liver cytosol.

The incubation of [4-14C]testosterone with adult male hamster liver cytosol at pH 6.7 yielded 5 beta-androstane-3 alpha, 17 beta-diol and small quantities of 5 beta-androstane-3 beta, 17 beta-diol, 17 beta-hydroxy-5 beta-androstan-3-one, 3 alpha-hydroxy-5 beta-androstan-17-one and androstenedione. The use of [4-14C]androstenedione as substrate yielded the same 5 beta-metabolites and also testosterone and a trace of epitestosterone. 5 beta-Androstane-3 alpha, 17 beta-diol was the major metabolite at "low" concentrations of substrate but testosterone and 3 alpha-hydroxy-5 beta-androstan-17-one became the major metabolites as the concentration of the substrate was increased. Small quantities of 5 beta-androstane-3,17-dione and 3 beta-hydroxy-5 beta-androstan-17-one were detected at "high" while 5 beta-androstane-3 alpha, 17 alpha-diol was detected at "low" concentrations of androstenedione. NADPH was more effective than NADH except in the formation of the 3 beta-steroids. Furthermore, the 3 beta-steroids were formed in maximum quantities at a lower pH than the other metabolites. The relative production of the metabolites was consistent with their respective spectrophotometrically determined degree of hydroxyl dehydrogenation.

Activity of 3 beta-hydroxysteroid dehydrogenase delta 4-5 isomerase in the human skin.

The activity of 3 beta-hydroxysteroid dehydrogenase delta 4-5 isomerase (3 beta-HSD) was assayed in various tissues microdissected from the freeze-dried human skin of 13 subjects. The sebaceous gland possessed the highest activity of 3 beta-HSD in the skin, while the apocrine sweat gland showed only one fourth of that activity. The vellus hair follicle showed nearly one half of the activity of the sebaceous gland, whereas the terminal hair follicle exhibited much lower activity. The activity of the epidermis and of the dermis were negligible. Incubation of fresh whole skin of the forehead with 7 alpha-3H-DHA and subsequent isolation of various tissues revealed that the metabolites identified in the sebaceous gland were androstanedione and androstenedione, whereas testosterone and/or dihydrotestosterone were not detected.

The identification and characterization of a new C19O3 steroid metabolite in the rat ventral prostate: 5 alpha-androstane-3 beta, 6 alpha, 17 beta-triol.

This study represents the first report of the formation of 5 alpha-androstane-3 beta, 6 alpha, 17 beta-triol (6 alpha-triol) by prostatic tissue. The 6 alpha-triol has been identified by rigorous methods and a chemical synthesis of this triol has been accomplished. This 6 alpha-triol is the major metabolite of 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) in the rat ventral prostate. A minor metabolite of 3 beta-diol has been identified as 5 alpha-androstane-3 beta, 7 alpha, 17 beta-triol (7 alpha-triol). Using a variety of C19 androstane substrates, the 6 alpha- and 7 alpha-triols were always found as the major components of the total 3 beta-hydroxy-5 alpha-androstane metabolites produced by the ventral prostate. Following intraperitoneal injection of 3H-3 beta-diol, both 6 alpha- and 7 alpha-triol were formed in vivo by the ventral prostate and found in the blood. The 6 alpha- and 7 alpha-triols were found to possess no androgenic activity when tested by the ventral prostatic growth bioassay in the castrate rat.

Characterization of two new enzymatic activities of the rat ventral prostate: 5 alpha-androstane-3 beta, 17 beta-diol 6 alpha-hydroxylase and 5 alpha-androstane-3 beta, 17 beta-diol 7 alpha-hydroxylase.

This study has characterized two new enzymatic hydroxylase activities specific for 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) in the rat ventral prostate: 5 alpha-androstane-3 beta, 17 beta-diol 6 alpha-hydroxylase (6 alpha-hydroxylase) and 5 alpha-androstane-3 beta, 17 beta-diol 7 alpha-hydroxylase (7 alpha-hydroxylase). Both of these irreversible hydroxylase activities require NADPH and are localized in the microsomal fraction of the prostate. The apparent Km for 3 beta-diol is 2.5 microM for both the 6 alpha- and 7 alpha-hydroxylase activities. The apparent Km for NADPH is 7.6 microM for the 6 alpha-hydroxylase and 7.0 microM for the 7 alpha-hydroxylase. The pH optimum for both activities is 7.4. Several steroid inhibitors of these hydroxylase activities in vitro were identified including cholesterol, progesterone, and estradiol. Estradiol was found in vitro to be a noncompetitive inhibitor (Ki = 5 microM). Injection of estradiol into intact male rats, simultaneously receiving exogenous testosterone, also produced a significant lowering of the 6 alpha-plus 7 alpha-hydroxylase activities. Both the 6 alpha- and 7 alpha-hydroxylase were found to be androgen sensitive. Following castration there is a rapid decrease in both activities.

3-Alpha-androstanediol and prostatic growth: comparison of 3-alpha-androstanediol formation in prostates from 8 species including man and dog.

To determine whether the formation of 3-alpha-androstanediol is critical for androgen-mediated growth of the prostate the conversion of dihydrotestosterone to 3-alpha-androstanediol was assessed in homogenates of 60 normal prostates from 8 species. Rates (nmol. times gm. tissue(-1) times hour(-1)) in the presence of reduced nicotinamide adenine dinucleotide phosphate as cofactor were as follows: dog 271, mouse 200, rat 160, opossum 109, rabbit 24, guinea pig 13, man 11 and cat 9. There was no correlation between prostate size and 3-alpha-androstanediol formation in the entire group. Therefore, either differences in the response to 3-alpha-androstanediol within the prostate or variations in the metabolism of 3-alpha-androstanediol must be more important than the rate of its formation for the development of prostatic hypertrophy in the dog.

Production of testosterone, 5 alpha-androstane-3 alpha, 17 beta-diol and androsterone by dispersed testicular interstitial cells and whole testes in vitro.

The production of 5 alpha-androstane-3 alpha, 17 beta-diol (androstanediol), androsterone and testosterone by whole rat testes and testicular interstitial cells dispersed with collagenase was studied in vitro. Luteinizing hormone stimulated the production of each of the androgens by cells prepared from 31- to 34-day-old rats. Half maximum stimulation of the production of each androgen occurred with approximately 3.5 ng NIH-LH-B9/ml medium. Androstanediol was the predominant product then androsterone and then testosterone. Luteinizing hormone stimulated the production of testerone, but not androstanediol or androsterone by dispersed interstitial cells from 200-day-old rats. The time-course of production and the effect of the concentration of cells on the production of these androgens suggested that in dispersed testicular interstitial cells from immature animals androstanediol and androsterone are formed, at least partially, by the metabolism of testosterone. In these experiments LH-stimulated testosterone production increased during incubation for 15--60 min and then remained constant up to 180 min. The concentrations of androstanediol and androsterone increased in a linear manner during incubation for 60--180 min. Varying the number of cells incubated yielded a positive correlation between cell concentration and the ratio 5 alpha-reduced androgen : testosterone produced. Luteinizing hormone stimulated production of each androgen by whole tests obtained from rats at 30--175 days of age. The serum concentration of testosterone in these rats increased abruptly at 50 days of age. Significant changes in androgen production in vitro also observed at this age included: (1) increased production of the three steroids when incubated in either the presence or absence of LH and (2) testosterone production, either in the presence or absence of LH, which represented a greater percentage of the total production of the three androgens.

Steroid metabolism by the lung: conversion of dihydrotestosterone to 5 alpha-androstan-3 alpha, 17 beta-diol by rat lung tissue in vitro.

The potential of lung tissue of adult male rats metabolize dihydrotestosterone (DHT) in vitro was examined. Within 3 min, a homogenate of 100 mg lung tissue, cleared of blood by perfusion before homogenization, metabolized 90% of the [3H]DHT substrate. Appoximately 80% of the DHT was converted to 5 alpha-androstan- alpha, 17 beta-diol. The amount of 5 alpha-androstan-3 alpha, 17 beta-diol formed during a 5-min incubation increased linearly, with substrate concentrations ranging from 3.3 x 10(-8) to 3 x 10(-6) M. Thus, the capacity of rat lung tissue to metabolize DHT in vitro and the rate of 3 alpha-reduction of DHT are sufficiently great to consider the possibility that lung may be responsible for the rapid clearance of DHT from the circulation in this species.

Peripheral and ovarian venous concentrations of various steroid hormones in virilizing ovarian tumors.

The ovarian-peripheral gradients of various delta4 and delta5 steroids were determined for a patient with virilizing arrhenoblastoma. The high peripheral testosterone level accompanying this tumor results from increased precursor supply from both the delta4 and delta5 pathways, with the delta5 pathway predominating, and from negligible aromatase activity. A review of 45 cases of androgen-producing ovarian tumors with measurement of peripheral venous testosterone, and of 24 cases with measurement of ovarian venous testosterone, and a comparison with findings in 159 patients with hirsutism of functional origin reveal the following 1) An androgen-producing tumor must be ruled out when peripheral testosterone exceeds 2 ng/ml; 2) an ovarian venous testosterone level exceeding 20 ng/ml generally accompanies a tumor, particularly when the tumor is less than 5 cm in diameter; and 3) virtually all (98%) of the tumors reviewed were accompanied by virilization, regardless of the peripheral concentration of testosterone.

Formation of 5alpha-androstane-3alpha,17beta-diol by normal and hypertrophic human prostate.

The 3-keto reduction of [1,2-3H]dihydrotestosterone to 3alpha- and 3beta-androstanediols was assessed in homogenates of 40 prostates obtained either at surgery or at medicolegal autopsy from men who had died suddenly. Formation of both androstanediols was demonstrable in cytosol and in microsomes, and both NADH and NADPH were effective cofactors for the two reactions. Formation of the two steroids was not influenced by storage of the gland for up to 8 h prior to processing. When NADPH was cofactor, the formation of 3alpha- and 3beta-androstanediol was significantly higher in microsomes and cytosol from hypertrophic than from normal glands.

Modification of testicular steroid metabolism in the rat during gonadotrophin administration.

The administration of human chorionic gonadotrophins to adult rats stimulates the formation of testosterone, 7alpha-hydroxy-testosterone and 5alpha-androstanediol in incubated testes. When the gonadotrophins are injected for several days, the testosterone formation is maintained at a high level; however, the transformation to 7alpha-hydroxy-testosterone decreases progressively to subcontrol levels, while 5alpha-androstanediol is produced in greater amounts.