Rapid effect of testosterone on ribonucleic acid polymerase activity of rat ventral prostate

Soluble proteins of guinea pig seminal vesicle lumen: purification and partial characterization

Luminal contents of guinea pig seminal vesicle were extracted with 0.154 M NaCl and the soluble protein fraction was studied by DEAE-cellulose and Sephadex G-100 column chromatography; anionic, cationic, and SDS-polyarcylamide disc gel electrophoresis; isoelectric focusing; molecular weight determinations by SDS-polyacrylamide disc gel electrophoresis; analysis for neutral carbohydrate; sucrose density-gradient centrifugation for determination of sedimentation coefficients; and amino acid analyses. Four protein fractions (referred to as proteins 1, 2, 3, and 4 in order to elution) were obtained by DEAE-cellulose column chromatography. Proteins 1, 2, and 4 gave single major bands in multiple disc gel electrophoretic systems. Protein 3 gave one major band and one minor component believed to be a fragment of a primary vesicular protein. Protein 1 is very basic and probably represents the clotting protein of guinea pig semen. The three nonclotting proteins could not be detected in serum and are probably intrinsic to seminal vesicle epithelium. All four proteins were found in animals weighing 700 g or more; only two of the three nonclotting proteins were found in more than half of the younger animals. This makes it even more likely that one or more of the nonclotting proteinc could serve as a useful gene marker in studies of androgen mechanisms.

Androgen regulation of the largest subunit of RNA polymerase II in the rat ventral prostate

One of the dramatic changes in the prostate during androgen manipulation is the alteration in cellular content of total RNA - the amount of total RNA in each cell. The abundance of cellular total RNA correlates with the RNA polymerase (RNAP) activity in the prostate. One possible mechanism of androgen regulation of RNAP activity involves the regulation of RNAP expression. Western blot analysis showed that the largest subunit of the RNAP II, an essential component of the transcriptional machinery for mRNA, is indeed regulated by androgens. Castration down-regulates the protein level of RNAP II, whereas androgen replacement up-regulates the protein. However, androgen manipulation does not have consistent effects on the phosphorylation of the C-terminal domain (CTD) of the RNAP II. Androgen regulation of the RNAP II protein expression was also observed in the seminal vesicles but not in the thymus and liver, indicating that androgen regulation of RNAP II protein expression appears to be limited to the male sex accessory organs. These observations suggest that RNAP II plays an essential role in androgen action in male sex accessory organs.

Molecular mechanism of androgen action

Androgens affect the growth and development of a wide variety of cell types in both males and females and produce their effects by binding to androgen receptors, which modulate the transcription of specific genes. Testosterone is the major active androgen circulating in blood, but in many tissues it is metabolized by 5alpha-reductase to 5alpha-dihydrotestosterone, which binds to and activates the androgen receptor. Androgen receptors are members of the nuclear receptor family of transcription factors, and these nuclear receptors control transcription by recruitment of a variety of co-activators and co-repressors. Mutations in the androgen receptor and 5alpha-reductase can affect male sexual development. 5alpha-Reductase is also critical for parturition and fetal survival in mice. Inhibitors of 5alpha-reductase are being used increasingly to treat some androgen-dependent disorders. Because androgens also suppress the growth of certain cancer cells, they might also have a role in treating prostate cancer.

The metabolic fate of the anti-androgenic agent, oxendolone, in man

After intramuscular administration of 16 beta-ethyl-17 beta-hydroxy-4-4-[4-14C]estren-3-one (14C-oxendolone; 300 mg) to 3 human subjects, excretion of 14C was very slow and incomplete despite a 20-day sample collection period. During this time, means of 37% and 21% of the administered 14C were recovered in urine and faeces, respectively, and if excretion continued at the same rate, approximately 90% of the administered 14C would have been excreted during 5-12 weeks. Peak plasma 14C concentrations were reached at 3-6 days after dosing, when they represented 0.2-1.1 micrograms equiv./ml, and declined very slowly thereafter with a half-life of 5.0-6.6 days. Concentrations of unconjugated drug-related steroids circulating in plasma never exceeded about 0.1 microgram/ml. Mass spectroscopic analysis of isolated urinary and faecal metabolites indicated that the principal routes of biotransformation of oxendolone in man are similar to those of the endogenous androgens-namely, reduction of the 4,5-double bond, further reduction of the saturated 3-ketone to the 3 alpha-hydroxysteroid, and oxidation of the 17 beta-alcohol to the corresponding ketone, followed by conjugation, mainly with glucuronic acid, and excretion in the urine and bile.

Intracellular inactivation, reactivation and dynamic status of prostate androgen receptors

The dynamic status of the androgen receptor in prostate cells was studied by incubation of rat ventral prostate with radioactive 17beta-hydroxy-5alpha-androstan-3-one (5alpha-dihydrotestosterone) in the presence and absence of respiratory poisons and inhibitors of protein and RNA synthesis and also by isotope chasing of the radioactive androgen-receptor complexes. The androgen receptor in the prostate appears to go through a dynamic process of recycling between the cytoplasm and the nucleus as well as an inactivation process. The radioactive androgen-receptor complex, however, is maintained at a constant level for at least 2h during incubation at 37 degrees C, even in the absence of new protein synthesis, suggesting that early androgen actions may not require a depletion of a major portion of cellular receptor. In the presence of 2,4-dinitrophenol, the androgen receptor is rapidly deactivated (half life, 2min). The inactive receptor can be reactivated efficiently by an energy-dependent process, even in the absence of protein synthesis. Receptor binding of androgen and nuclear chromatin binding of the androgen-receptor complex are fast processes; half-maximum binding can be achieved within 1 and 10min respectively. On the contrary, the overall process of the release of the receptor complex from nuclear chromatin and its reappearance in the cytosol fraction has a long half life of about 70min. This slow process may reflect the involvement of the steroid-receptor complex in a time-consuming mechanism that is essential for hormone responses. Actinomycin D can increase the nuclear receptor level by 50% or more. This increase is not due to a decrease in the rate of receptor release from nuclei or to inhibition of DNA degradation by the antibiotic.

Disposition and metabolism of 16 beta-ethyl-17 beta-hydroxy-4-estern-3-one (TSAA-291), a new antiandrogen, in rats

Matabolic fate of a new antiandrogen, 16 beta-ethyl-17 beta-hydroxy-4-estren-3-one (TSAA-291), was studied in rats. 14C-TSAA-291 intramuscularly injected as an aqueous suspension was absorbed gradually to give an increase in the plasma level which attained a plateau at 0.5 h, persisted till 8 h and then declined with an approx. half-life of 3.6 days. The drug was widely distributed in tissues, with the concns. almost equal to or higher than that in the plasma. The 14C-drug was eliminated mostly as metabolites within 10 days after dosing with higher activities found in the feces than in urine. Biliary 14C effectively underwent enterohepatic cycling. Biliary metabolites of TSAA-291 were characterized by the combined use of deuterium labeling and GLC-MS analysis. The metabolites identified were as follows: the parent drug, monohydroxy TSAA-291 having the additional hydroxy function in the steroid skeleton, 17 beta-hydroxy-16 beta-(1 xi-hydroxyethyl)-4-estren-3-one, 16 beta-ethyl-17 beta-hydroxy-5 beta-estran-3-one, 16 beta-ethyl-17 beta-hydroxy-5 alpha-estran-3-one, 16 beta-ethyl-5 beta-estrane-3 alpha, 17 beta-diol, 16 beta-ethyl-5 alpha-estrane-3 alpha, 17 beta-diol, 16 beta-ethyl-3 alpha-hydroxy-5 beta-estran-17-one and 16 beta-ethyl-3 alpha-hydroxy-5 alpha-estran-17-one. Monoketodihydroxy and/or trihydroxy metabolites were also detected in the bile.

Regulation of L-ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase in rat ventral prostate and seminal vesicle

1. The activities of l-ornithine decarboxylase (EC 4.1.1.17) and S-adenosyl-l-methionine decarboxylase (EC 4.1.1.50) were dramatically enhanced in both the ventral prostate and the seminal vesicle of castrated rats in response to androgenic stimulation. The time course of the stimulation of ornithine decarboxylase together with the quantitatively different response of adenosylmethionine decarboxylase to testosterone treatment in the prostate gland and seminal vesicle indicated that the enhancement in polyamine synthesis in the ventral prostate may reflect both cellular proliferation and the restoration of the secretory functions of the organ. In the seminal vesicle, however, the stimulation of the polyamine-biosynthetic pathway more closely resembled the pattern found in other rat tissues, such as regenerating liver, undergoing compensatory growth. 2. Ornithine decarboxylase activity in the ventral prostate and especially in the seminal vesicle of sexually mature rat was diminished in vivo by various short-chain diamines such as 1,2-diaminoethane, 1,3-diaminopropane and putrescine (1,4-diaminobutane). These diamines had no direct effect on the enzyme activity in vitro. 3. In contrast with the marginal decrease in ornithine decarboxylase activity produced by diaminoethane in the ventral prostate of non-castrated animals, repeated injections of the latter amine completely prevented the intense stimulation of the enzyme activity in the ventral prostate and seminal vesicle of castrated rats at 24h after the commencement of testosterone treatment. 4. The decrease in ornithine decarboxylase activity observed after injections of diamines (putrescine) in the ventral prostate was apparently associated with a similar decrease in the amount of immunoreactive protein as revealed by immunotitration of the enzyme with antiserum to rat ornithine decarboxylase.

RNA polymerase activities in isolated nuclei of guinea pig seminal vesicle epithelium: influence of castration and androgen administration

Nuclei from seminal vesicle epithelium of adult guinea pigs were isolated in hypertonic sucrose solution. The incorporation of [3H]UTP by the isolated nuclei into acid-precipitable products was studied. Incorporation required ATP, GTP, CTP, UTP, and Mg+2. It was inhibited by addition of actinomycin D, deoxyribonuclease, or pyrophosphate to the reaction mixture. Thus, incorporation of [3H]UTP by isolated nuclei had the same characteristics that have been demonstrated for the reactions catalyzed by nuclear RNA polymerases. Using alpha-amanitin as a metabolic tool, we established concentrations of (NH4)2SO4. Mg+2, and nucleotides that give maximum assayable activities of nuclear RNA polymerases I and II. When the activities of polymerases I and II were measured in isolated seminal vesicle nuclei of guinea pigs that had been castrated 4 days earlier, a marked decrease in activities was found relative to control values (nuclei from intact animals). No further decrease was found 8 days after castration. Diminished accessibility to the nuclear DNA template and a decrease in the concentration of RNA polymerase molecules seemed to be responsible for the observed effects of castration on activities of RNA polymerases. An increase in ribonuclease activity did not seem to be responsible for the effects of castration. Activities of the enzymes did not change 2, 3, or 4 hours after intraperitoneal injection (2 mg/kg body weight) of each of five different androgens. Similarly, a single intraperitoneal injection of testosterone did not restore enzyme activity of polymerade I or II at any time during the first 24-hour period after hormone administration.

Intracellular localisation of 5alpha-dihydrotestosterone in human benign prostatic hypertrophy

When slices of benign hypertrophied human prostate and abdominal muscle were incubated with either [3H]testosterone or 5alpha-dihydro[3H]testosterone, the uptake of radioactivity by prostatic tissue was significantly higher than that of the muscle (P less than 0.01). The uptake of labelled androgen by prostatic tissue could be significantly reduced by adding the unlabelled steroid to the incubation medium. After the incubation of prostatic tissue with 5alpha-dihydro[3H]testosterone, the amount of the radioactivity taken up by the whole homogenate and the nuclear preparation of the prostatic tissue were measured. DNA content of the nuclei and the whole homogenate was also estimated. The mean+/-S.E.M. of 5alpha-dihydrotestosterone associated with the nuclei was 65+/-4.4%, ranging from (52.2-79.8%). The activity of acid phosphatase was measured in 30 samples of prostatic tissue. The mean +/- S.E.M. was 20.7+/-1.5 U/g tissue (9.8+/-0.9 U/mg DNA). The correlation between the activity of this enzyme and the uptake of androgen by prostatic tissue is evaluated.

The differential response of prostatic nucleolar and extra-nucleolar protein phosphokinase activities following androgen deprivation

Protein phosphokinase activities of nucleolar and extra-nucleolar compartments of rat ventral prostate nuclei were measured using the model acidic phosphoprotein, dephosphophosvitin, as substrate. Following orchiectomy, the activity in both of these fractions declined; however, the kinase activity of the nucleolus decreased at a much greater rate than that in the extra-nucleolar portion of the nucleus. Testosterone maintenance of castrated animals prevented this decline in activity. The regulation of protein phosphokinases which phosphorylate prostatic nucleolar acidic proteins may be an important mechanism in the androgen mediated activation of the nucleolus in this target tissue.

Steroid-induced early protein synthesis in rat uterus and prostate

An early 'induced protein', after exposure of the rat uterus to estradiol, is detected among the soluble proteins with a double-labelling technique and electrophoretic fractionation. Efforts have been directed to establish the subcellular distribution of the induced protein, since such a protein, observable 1 h after hormone administration, may play an important role in the subsequent amplified responses, especially in terms of RNA synthesis. Moreover such an early discrete induced protein was sought in a comparable system responding to another hormone, namely prostate and seminal vesicles under androgens. The induced protein was not found in uterine nuclei of 21-day-old rats after 1 h of estradiol action in vivo and 1 h of tissue incubation with labelled leucine. This negative result summarizes a search among different nuclear protein fractions using various procedures; nor was induced protein observed in mitochondrial and microsomal pellets. Contrary to these negative findings, slight changes of histone labelling were observed under the experimental conditions used to demonstrate induced protein. In addition histone acetylation was increased after 1 h of estradiol action in vivo and 15 min tissue labelling in vitro with radioactive acetate. Furthermore, an increase in total protein synthesis between 0 and 2 h after estradiol action was observed, the relative increase of incorporation of radioactive leucine into protein of estradiol-treated vs non-stimulated uteri being corrected for variations of the acid-soluble radioactive leucine pool. Attempts to obtain an early and discrete induced protein with androgens in prostate and seminal vesicles of immature or castrated rats after different times of exposure to testosterone, androstanolone and estradiol have been unsuccessful. The contribution of both negative and positive findings in steroid-induced early protein synthesis is discussed in the context of the current knowledge of hormone action.

Effects of alpha-amanitin on the stimulation of prostatic ribonucleic acid polymerase by prostatic steroid-protein receptor complexes

Stimulation of prostatic RNA polymerase in vitro by prostatic 17beta-hydroxy-5alpha-androstan-3-one (5alpha-dihydrotestosterone)-receptor complexes has been previously reported. By use of the selective inhibitor, alpha-amanitin, we have shown that both nucleolar and extranucleolar RNA polymerase activities may be stimulated, but stimulation is abolished at high ionic strength.

A reappraisal of the effects of adenosine 3':5'-cyclic monophosphate on the function and morphology of the rat prostate gland

1. A comparison was made of the binding of 5alpha-dihydrotestosterone (17beta-hydroxy-5alpha-androstan-3-one) and cyclic AMP in the rat prostate gland. Distinct binding mechanisms exist for these compounds, and cyclic AMP cannot serve as a competitor for the 5alpha-dihydrotestosterone-binding sites and vice versa. In contrast with the results obtained with 5alpha-dihydrotestosterone, very small amounts of cyclic AMP are retained in nuclear chromatin and the overall binding of this cyclic nucleotide is not markedly affected by castration. 2. Androgenic stimulation does not lead to major increases in the adenylate cyclase activities associated with any subcellular fraction of the prostate gland. Accordingly, changes in the concentration of cyclic AMP in the prostate gland after hormonal treatment are likely to be small, but these were not measured directly. 3. When administered to whole animals in vivo, small amounts of non-degraded cyclic AMP are found in the prostate gland but sufficient to promote an activation of certain carbohydrate-metabolizing enzymes in the cell supernatant fraction. The stimulatory effects of cyclic AMP were not evident with cytoplasmic enzymes engaged in polyamine synthesis or nuclear RNA polymerases. These latter enzymes were stimulated solely by the administration of testosterone. 4. By making use of antiandrogens, a distinction can be drawn between the biochemical responses attributable to the binding of 5alpha-dihydrotestosterone but not of cyclic AMP. Evidence is presented to suggest that the stimulation of RNA polymerase, ornithine decarboxylase and S-adenosyl-l-methionine decarboxylase is a consequence of the selective binding of 5alpha-dihydrotestosterone. Only the stimulation of glucose 6-phosphate dehydrogenase can be attributed to cyclic AMP or other metabolites of testosterone. 5. Overall, this study indicates that the formation of cyclic AMP is not a major feature of the androgenic response and affects only a restricted number of biochemical processes. Certainly, cyclic AMP cannot be considered as interchangeable with testosterone and its metabolites in the control of the function of the prostate gland. This difference is additionally emphasized by the failure of cyclic AMP to restore the morphology of the prostate gland in castrated animals; morphological restoration only follows the administration of androgens.

Studies on the solubilized ribonucleic acid polymerase from rat ventral prostate gland

1. By using ultrasonic treatment in media of high ionic strength, the RNA polymerase activities associated with prostatic nuclei and nucleoli can be completely solubilized. Such enzyme preparations are entirely dependent on the provision of added DNA for full activity. 2. The solubilized enzymes from the nucleolar and extranucleolar regions can be separated by ion-exchange chromatography. 3. Based on differences in the optimum DNA templates, pH optima and the effects of ammonium sulphate on the activities in vitro, Mn(2+)- and Mg(2+)-specific enzymes are associated with both the nucleolar and extranucleolar regions of prostatic nuclei. 4. Androgenic hormones administered in vivo have a particularly pronounced effect on the activity of Mg(2+)-dependent enzyme associated with the isolated prostatic nucleolus. 5. Time-course experiments in vivo show that androgens induce a rapid stimulation of the solubilized Mg(2+)-dependent nucleolar enzyme before a pronounced activation of nucleolar chromatin can be measured. 6. The implications of these findings to the mechanism of action of androgenic steroids are discussed.

Steroid hormones: effects on adenyl cyclase activity and adenosine 3',5'-momophosphate in target tissues

The adenyl cyclases of chick oviduct and rat prostate were not stimulated by estrogen and testosterone, respectively, suggesting that growth and differentiation of these target tissues are not mediated by adenosine 3',5'-monophosphate. Estrogen acutely activated adenyl cyclase in the castrate rat uterus, but this was prevented by administration of DL-propranolol, suggesting that the effect was mediated by catecholamines. Progesterone produced a delayed stimulation of oviduct adenyl cyclase preceding and concomitant with the induction of synthesis of avidin.

Concentrations of putrescine and polyamines and their enzymic synthesis during androgen-induced prostatic growth

1. Castration of adult rats resulted in marked decreases in the amounts of putrescine, spermidine and spermine in the ventral prostate gland. Spermidine concentrations decline rapidly over the first 11 days after androgen withdrawal, reaching a value of only 12% of normal controls. Spermine concentrations diminish more slowly, reaching 24% of normal within 11 days. The spermidine/spermine molar ratio falls from 0.9 to 0.46 under these conditions. Putrescine concentrations decrease by 70% at 7 days after castration and then remain constant for some days. 2. After daily injections of testosterone propionate to rats castrated 7 days previously, prostatic spermidine and putrescine concentrations increase significantly within 24h; normal or even greater values are observed within 8 and 4 days respectively. In contrast, the spermine concentration does not increase until 5 days after commencement of androgen treatment. 3. The activities of two enzymes involved in polyamine biosynthesis (ornithine decarboxylase and a putrescine-activated S-adenosyl-l-methionine decarboxylase system) were greatly decreased soon after castration: after 7 days the respective values were 15% of normal for ornithine decarboxylase and 7% of normal for putrescine-dependent decarboxylation of S-adenosyl-l-methionine. Injection of testosterone propionate into animals castrated 7 days previously induced a rapid increase in both enzymic activities: ornithine decarboxylase was doubled in 6h, and increased three- to four-fold within 48h, whereas the putrescine-dependent decarboxylation of S-adenosyl-l-methionine doubled in 3h and increased tenfold within 48h of commencement of daily androgen treatments. 4. The activity of these enzyme systems was very low in the ventral prostates of hypophysectomized rats and was increased by administration of testosterone in a manner similar to that found in castrated rats. 5. Alterations in the activity of two ventral-prostate enzymes involved in ornithine production (arginase) and utilization (ornithine-2-oxoglutarate transaminase) that result from changes in the androgenic status of rats are described. 6. The findings presented suggest that the activities of ornithine decarboxylase and the putrescine-dependent S-adenosyl-l-methionine decarboxylase system, rather than ornithine concentrations, are rate-limiting for the formation of putrescine and polyamines in rat ventral prostate. 7. The relation of polyamines to androgen-induced prostatic growth is discussed with particular reference to the biosynthesis of proteins and nucleic acids.