Effects of antiandrogens on transformation and transcription activation of wild-type and mutated (LNCaP) androgen receptors

LNCaP cells contain androgen receptors with a mutation in the steroid binding domain (Thr 868 changed to Ala) resulting in a changed hormone specificity. Both the wild-type and mutated androgen receptors were transfected into COS cells. Transcription activation was studied in cells co-transfected with an androgen sensitive reporter (CAT) gene. The wild-type androgen receptor was activated by the agonist R1881, but the antiandrogens did not enhance transcription apart from a partial agonistic effect at high concentrations of cyproterone acetate. The mutated androgen receptor was fully activated by R1881, cyproterone acetate and hydroxyflutamide, but not by ICI 176,334. Receptor transformation to a tight nuclear binding state was studied by preparation of detergent washed nuclei and Western blotting with a specific antibody against the androgen receptor. Nuclei of COS cells transfected with wild-type receptor retained the receptor when the cells had been treated with the agonist R1881, partially retained receptors when treated with antiandrogen cyproterone acetate, but did not retain receptor when treated with hydroxyflutamide or ICI 176,334. The cells transfected with the mutated receptor additionally retained nuclear receptors after treatment with hydroxyflutamide. We conclude that each one of the three antiandrogens tested displayed different characteristics with respect to its effect on transformation and transcription activation.

Dehydroepiandrosterone antiestrogenic action through androgen receptor in MCF-7 human breast cancer cell line

The possible mechanisms of the inhibitory effect of Dehydroepiandrosterone (DHEA) on the estrogen-induced growth of MCF-7 human breast cancer cells were explored. The impairment of metabolic pathways, via the inhibition of glucose-6-phosphate dehydrogenase (G6PD) activity, was excluded: G6PD activity in MCF-7 homogenate was reduced by DHEA only at a very high concentration (50 microM), while no inhibitory action on the enzyme activity was detected when DHEA was added at the antimitotic concentrations (0.02-0.5 microM). A steroid receptor mediated effect was explored: DHEA might either activate androgen receptors (AR) or partially displace E2 from estrogen receptor (ER). The pure antiandrogens Flutamide and Hydroxyflutamide reversed the inhibitory effect of DHEA on MCF-7 cell growth, whereas both the nonsteroidal estrogen Diethylstilbestrol and the antiestrogen Tamoxifen were ineffective. Results demonstrate that the AR activation plays a pivotal role in the inhibitory action of DHEA on the E2-induced MCF-7 growth.

Influence of the anti-androgen hydroxyflutamide on in vitro development of mouse embryos

Hydroxyflutamide is a potent nonsteroidal anti-androgenic drug extensively used in laboratory investigations. Our present studies were aimed at determining whether this anti-androgen modulates development of embryos in vitro. One-cell and two-cell mouse embryos were collected by flushing the oviducts and cultured in defined culture media in the presence or absence of various doses of hydroxyflutamide. The development of embryos from one-cell and two-cell to blastocyst stage was assessed. Hydroxyflutamide caused a dose-dependent (0-100 micrograms ml-1) inhibition of development of both one-cell and two-cell embryos; 100% inhibition was observed at 20 micrograms ml-1. The adverse effects of hydroxyflutamide on two-cell embryo development were completely reversed by testosterone in a dose-dependent manner, but not by oestradiol and progesterone. These results indicate that the antiandrogen hydroxyflutamide inhibits early embryo development suggesting that it may be useful during the preimplantation period for preventing conception.

Steroid requirement for androgen receptor dimerization and DNA binding. Modulation by intramolecular interactions between the NH2-terminal and steroid-binding domains

Infection of Spodoptera frugiperda Sf9 insect cells with recombinant human androgen receptor (AR) baculovirus results in expression of a 118-kDa phosphoprotein that displays high affinity androgen binding and androgen-dependent targeting to the nucleus. Using the DNA mobility shift assay, specific in vitro binding of full-length AR to androgen response element DNA (ARE) requires intracellular hormone exposure. The ability of a variety of steroids to induce ARE binding paralleled their transcriptional potential. Certain antihormones, cyproterone acetate and RU486, promote ARE binding, but a pure antiandrogen, hydroxyflutamide, inhibits AR binding to ARE DNA. AR dimerization requires incubation of recombinant baculovirus-infected insect cells with androgen, but only when one or both components of the dimer contain the NH2-terminal domain. Based on the intensities of ARE binding and lack of binding to an ARE half-site, it appears that, unlike the glucocorticoid receptor, AR binds DNA primarily as a dimer. Thus, full-length baculovirus-expressed AR requires intracellular hormone exposure for dimerization and ARE binding to overcome inhibition imposed by the AR NH2-terminal domain. Antihormones with agonist activity promote dimerization and ARE binding, while a pure antiandrogen blocks AR DNA binding. It is concluded that intramolecular interactions between the NH2-terminal and steroid-binding domains are regulated by the specificity of hormone binding and modulate receptor dimerization and DNA binding.

Androgen receptor-mediated stimulation of 17 beta-hydroxysteroid dehydrogenase activity by dihydrotestosterone and medroxyprogesterone acetate in ZR-75-1 human breast cancer cells

The estrogen-sensitive human breast cancer cell line ZR-75-1 was used to study the regulation of 17 beta-hydroxysteroid dehydrogenase (17 beta HSD), the enzyme responsible for the interconversion of estrone (E1) and estradiol (E2). We, thus, investigated the effects of a 6-day exposure to various steroids or growth factors on the reductive (E1-->E2) and oxidative (E2-->E1) 17 beta HSD activities in ZR-75-1 cells as measured during a subsequent 16-h incubation with [3H]E1 or [3H]E2. The reductive 17 beta HSD activity was approximately 3-fold higher than the corresponding oxidative (E2-->E1) activity in control cells, thus favoring the predominance of E2 within the cell. Exposure to dihydrotestosterone (DHT) increased by 1.4-fold the reductive 17 beta HSD activity, with the stimulatory effect exerted at an EC50 value of 0.09 nM DHT, while the oxidative pathway was increased by 4.15-fold at an EC50 value of 0.17 nM. Incubation with medroxyprogesterone acetate, on the other hand, enhanced reductive 17 beta HSD activity by 1.87-fold, while the same treatment increased oxidative 17 beta HSD activity by 2.85-fold; the effects were exerted at EC50 values of 0.4 and 5 nM, respectively. The stimulatory effect of both steroids on 17 beta HSD activity was almost completely reversed by simultaneous exposure to the pure antiandrogen hydroxyflutamide (3 microM), thus supporting an action exerted through the androgen receptor. On the other hand, the synthetic estrogen ethynyl estradiol (EE2) inhibited the reductive and oxidative 17 beta HSD activities by 40% and 33%, respectively, whereas dexamethasone (300 nM) increased by 2.5- and 1.9-fold the reductive and oxidative 17 beta HSD activities, respectively. The present data showing that DHT and the androgenic compound medroxyprogesterone acetate favor the degradation of E2 into E1 suggest that the potent antiproliferative activity of these two compounds in E2-stimulated ZR-75-1 human breast cancer cells could be at least partially exerted through changes in 17 beta HSD activity.

Local perineal implants of anti-androgen block masculinization of the spinal nucleus of the bulbocavernosus

Female rats were injected with testosterone propionate on the 1st and 3rd days of life. In addition, some females received 200 micrograms of the anti-androgen, hydroxyflutamide. Females receiving anti-androgen directly to the perineum, including the muscles bulbocavernosus and levator ani, had fewer surviving spinal nucleus of the bulbocavernosus (SNB) motoneurons than did females receiving the anti-androgen systemically. These results indicate that androgen acts upon the target muscles to spare developing SNB motoneurons from death.

Regulation of androgen receptor mRNA and protein level by steroid hormones in human mammary cancer cells

The regulation of the human androgen receptor (AR) by steroid hormones in human mammary cancer cells was investigated using immunocytochemical and ligand binding assays for its protein and Northern blot analyses for the corresponding mRNA. MFM-223 cells contain high levels of ARs and are growth-inhibited by dihydrotestosterone (DHT). The AR protein is down-regulated to 57% of the control by 10 nM DHT after 24 h, and the corresponding mRNA is also reduced. The nonsteroidal antiandrogen hydroxyflutamide had no effect on the AR level, whereas after incubation with 1 microM cyproterone acetate a slight down-regulation was observed. The AR level was restored completely after release from a 7 day treatment with DHT. However, only 60% of the control level was restored, if the cells wer grown in the presence of DHT for 6 weeks. In androgen-pretreated cells the proliferation rate remained decreased even after the withdrawal of DHT. Concomitantly the distinct growth inhibition was lost. Transfection experiments demonstrated a reduced activity of the residual androgen receptor in these pretreated cells. In addition to the AR, EFM-19 cells also contain significant amounts of estrogen and progesterone receptors. EFM-19 cells are not growth inhibited by physiological concentrations of DHT. Autoregulation of AR was also found in this cell line. Additionally, reduced levels of AR protein and mRNA were found in EFM-19 cells after treatment with the synthetic progestin R5020. The maximum effect of R5020 was observed at the high concentration of 1 microM. Estrogen treatment with 10 nM 17 beta-estradiol for 3 days reduced the AR level only by 25%.

Local hyperthermia for prostatic disease: in vitro studies on human prostatic cancer cell lines

Local hyperthermia for benign and malignant prostatic disease remains largely empirical. In an attempt to understand the biological action of hyperthermia, and its potentiation by antiandrogen seen in clinical practice, the interaction of the two has been studied in prostatic cancer cell lines. Human prostatic cancer cell lines LNCaP and DU 145 were studied to examine the effects of heat shock treatment (HST), androgen (5 alpha-dihydrotestosterone: 5 alpha DHT) and antiandrogen (hydroxyflutamide: OH-Flut) on cell growth and survival. Response (measured as increased DNA content) to 5 alpha DHT demonstrated that LNCaP was androgen sensitive, whereas DU 145 was androgen insensitive; OH-Flut stimulated LNCaP growth but had no effect on DU 145 growth. Thermotolerance was exhibited by DU 145 cells but not by LNCaP cells. The combination of HST followed by OH-Flut markedly reduced survival of LNCaP cells compared with HST alone. This effect was not observed in DU 145 cells. The enhanced cytotoxic effect of antiandrogen and hyperthermia could minimise the effect of thermotolerance in malignant cells surviving initial hyperthermia treatment and might suggest real clinical value for the combination or sequence.

[Androgen receptors in muscles mediate the trophic effect of testosterone on axotomized neurons]

In order to further explore the hypothesis that muscles are the primary action site for testosterone, the present study examined the effect of androgen receptor blockade in effector muscles on the efficacy of testosterone in preventing neuronal cell loss following axotomy. Hydroxyflutamide (HF), an androgen antagonist that acts competitively at the hormone receptor site, was administered into muscles of the tongue when animals were treated with testosterone following unilateral transection of the hypoglossal and facial nerves. The ability of testosterone to prevent neuronal cell loss in the axotomized hypoglossal and facial motor nucleus was examined. The results demonstrated that hydroxyflutamide completely negates the survival-promoting effect of testosterone on axotomized motoneurons.

Effects of dihydrotestosterone and hydroxyflutamide on androgen receptors in cultured human breast cancer cells (EVSA-T)

The purpose of our study was to evaluate the effects of 5 alpha-dihydrotestosterone (DHT) and hydroxyflutamide (HF), alone or in combination, on androgen receptor (AR) dynamics and on cellular growth in cultured breast cancer cells (EVSA-T). The incubation of cells with DHT increased the concentration of nuclear AR after 24 and 48 h. HF was also able to promote the nuclear accumulation of AR after 24 and 48 h of treatment. When HF-treated cells are incubated with DHT, the nuclear AR concentration is lower than that found in cells treated with DHT alone. We conclude that HF acts by increasing nuclear accumulation of receptor-antiandrogen complexes. Moreover, DHT stimulates cell growth while HF has an inhibitory effect. Thymidine incorporation in cells also increased after DHT treatment and decreased after HF incubation. The HF-induced inhibition of cell growth persisted both after renewal of the medium and after the addition of DHT to cultures. It may be hypothesized that either DHT is converted to inactive metabolites or that HF exerts a persistent inhibitory effect. In the latter case, the antiandrogen action of HF could be exerted by retention of high levels of antiandrogen in cells or by such a depressed protein synthesis that the renewal of growth is slower than the 48 h period studied.

The effect of androgen, estrogen, and growth factors on the proliferation of cultured fibroblasts derived from human fetal and adult prostates

Stromal enlargement plays a key role in the development of benign prostatic hypertrophy in humans. Human prostatic fibroblasts were obtained from fetal and adult prostates and characterized as to their androgen and estrogen receptor status and growth in response to dihydrotestosterone (DHT), estradiol (E2), hydroxyflutamide (OH-FLU), hydrocortisone, basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF). In addition, the ability of hormones and growth factors to induce the messenger RNA (mRNA) for the c-fos protooncogene was assessed as a measure of the early, direct effects of these compounds on cellular proliferation. Nuclear androgen receptors were demonstrable by immunocytochemistry in both fetal and adult cells. Nuclear estrogen receptor staining was negative. Neither E2 nor hydrocortisone increased cellular proliferation. Both EGF and bFGF did increase cellular growth. DHT (10(-8)-10(-7) M) had a significant stimulatory effect on cell growth only in serum-free media. OH-FLU addition enhanced DHT induced proliferation. Changing the media during the course of the experiment obliterated the stimulatory effect of DHT. Both EGF (10 ng/ml) and bFGF (20 ng/ml) increased the mRNA for the c-fos protooncogene. DHT (10(-7) M) did not induce the mRNA for c-fos. We conclude that EGF, bFGF, and DHT (especially in combination with OH-FLU) increase the proliferation of human prostatic fetal and adult fibroblasts in vitro. E2 has no effect on fibroblast proliferation. The stimulatory effects of EGF and bFGF are direct, whereas the effect of DHT appears to be indirect, possibly mediated via the increased production and/or secretion of growth factors.

Androgen locally regulates rat bulbocavernosus and levator ani size

Adult male rats were gonadectomized, and small Silastic capsules filled with hormone were sutured to each bulbocavernosus and levator ani muscle complex (BC/LA). In the first experiment, one capsule contained testosterone (T), while the capsule on the contralateral muscles contained the antiandrogen hydroxyflutamide (hFl). The intent of this treatment was to provide a focus of androgenic stimulation to the muscles on one side. After 30 days, animals were sacrificed, and the BC/LA muscle pairs were removed, weighed, and compared. BC/LAs receiving T treatment were heavier than those receiving hFl treatment (p less than 0.0001), with an average weight difference of 12%. Muscle fibers from T-treated BCs were significantly larger in diameter than those from contralateral, hFl-treated BCs. These results indicate that androgen exerts its anabolic effect by acting locally upon a cell population within or near the BC/LA. When hFl and blank capsules were implanted in castrated males, the hFl-treated muscles were significantly heavier (by 9%), demonstrating an anabolic effect of hFl in the absence of androgen, and refuting the idea that hFl may have caused local toxic effects in the first experiment. Gonadectomized animals given T versus blank capsules had T-treated muscles that were 8% heavier than the blank-treated side. Muscle weights were also compared in animals receiving bilateral denervation of the BC/LA at the time of T and hFl capsule implantation and gonadectomy; local testosterone treatment failed to affect BC/LA weights in these denervated muscles.

Evidence that testosterone regulates Leydig cell 3 beta-hydroxysteroid dehydrogenase-isomerase activity by a trans-acting factor distal to the androgen receptor

Leydig cells are a target for their own steroid product, testosterone, and thus could be subject to short-loop feedback regulation by androgens. The authors previously reported that 3 beta-hydroxysteroid dehydrogenase-isomerase (3 beta HSD) activity was higher in freshly isolated Leydig cells from C57BL/6J than those from C3H/HeJ inbred mice. To determine whether this strain-related difference in 3 beta HSD activity could be mediated by differential sensitivity to feedback effects of testosterone, Leydig cells from the two strains were cultured in the presence or absence of testosterone, the synthetic androgen receptor agonist, mibolerone, or the nonaromatizable androgen, dihydrotestosterone. After 7 days of treatment, all three androgens significantly decreased 3 beta HSD activity in Leydig cells from C57BL/6J, but not from C3H/HeJ mice. When Leydig cells were cultured with hydroxyflutamide, an androgen receptor antagonist, the effect of testosterone was negated. To determine whether the strain-related difference in sensitivity to testosterone was mediated by a difference in the androgen receptor protein, Leydig cells from reciprocal F1 hybrid lines of mice were cultured in the presence or absence of testosterone. Testosterone treatment inhibited 3 beta HSD activity in both F1 lines to the same extent as observed for Leydig cells from C57BL/6J mice. Thus, there is a strain-related difference in the response to testosterone, but it cannot account for the strain-related difference in Leydig cell 3 beta HSD activity because the high 3 beta HSD strain (C57BL/6J) is the sensitive strain. Although the effect on C57BL/6J Leydig cells is androgen receptor-mediated, the dominant effect of testosterone on both F1 lines rules out a difference in the androgen receptor protein per se. However, the data are consistent with the difference being in a trans-acting factor distal to the androgen receptor.

Measurement of androgen sensitivity in the human prostate in in vitro three-dimensional histoculture

We have adopted an in vitro three-dimensional histoculture technique for assay of androgen sensitivity in explants of human benign prostatic tissue. The assay is based on the uptake of 3H-thymidine/micrograms protein in explants of prostate incubated in parallel with dihydrotestosterone (DHT) and hydroxyflutamide (HF) controls. The ratio of 3H-thymidine/micrograms protein in DHT treated samples per 3H-thymidine/micrograms protein in HF treated samples provides an index of androgen sensitivity. The DHT/HF index measured in 24 BPH specimens averaged 3.6. To determine the specificity of the HF effect, we measured the DHT/HF index in a single prostate at different concentrations of HF in the presence of fixed concentrations of DHT (2 x 10(-8) M) and noted a dose-response relationship. In addition we noted no effects of HF on 3H-thymidine incorporation over a range of 2 x 10(-4)M compared to 2 x 10(-7)M, except at the highest concentration. Of surprise was the finding of an average DHT/HF index in 5 different nonprostate tissues, including breast, uterus, colon, kidney, and thyroid, that was similar to the index found in prostates. We plan to adapt this androgen sensitivity assay to measure the DHT/HF index in biopsy-size samples of prostate, since such an assay could then be utilized to determine androgen sensitivity in individual patients with prostate cancer.

Characteristics of the biphasic action of androgens and of the potent antiproliferative effects of the new pure antiestrogen EM-139 on cell cycle kinetic parameters in LNCaP human prostatic cancer cells

The most potent steroid in human prostatic carcinoma LNCaP cells, i.e., dihydrotestosterone (DHT), has a biphasic stimulatory effect on cell proliferation. At the maximal stimulatory concentration of 0.1 nM DHT, analysis of cell kinetic parameters shows a decrease of the G0-G1 fraction with a corresponding increase of the S and G2 + M fractions. In contrast, concentrations of 1 nM DHT or higher induce a return of cell proliferation to control levels, reflected by an increase in the G0-G1 fraction at the expense of the S and especially the G2 + M fractions. Continuous labeling for 144 h with the nucleotide analogue 5'-bromodeoxyuridine shows that the percentage of cycling LNCaP cells rises more than 90% after treatment with stimulatory concentrations of DHT, whereas in control cells as well as in cells treated with high concentrations of the androgen, this value remains below 50%. Although LNCaP cells do not contain detectable estrogen receptors, the new pure steroidal antiestrogen EM-139 not only reversed the stimulation of cell proliferation and cell kinetics induced by stimulatory doses of DHT but also inhibited basal cell proliferation.

Effects of the antiandrogen hydroxyflutamide on progesterone secretion by preovulatory rat follicles in vivo and in vitro

Serum and ovarian progesterone levels and in vitro production of progesterone by preovulatory follicles were measured on proestrus in pregnant mare's serum gonadotropin (PMSG) primed immature rats in which the luteinizing hormone (LH) surge and ovulation were blocked by administration of the antiandrogen hydroxyflutamide. Serum progesterone levels observed at 12:00 on proestrus were significantly elevated, twofold above those observed in vehicle-treated controls, by in vivo administration of 5 mg hydroxyflutamide 4 h earlier. In control rats, proestrous progesterone did not increase until 16:00, in parallel with rising LH levels of the LH surge. No LH surge occurred in the hydroxyflutamide-treated rats, ovulation was blocked, and serum progesterone declined throughout the afternoon of proestrus, from the elevated levels present at 12:00. Administration of human chorionic gonadotropin (hCG) at 11:00 advanced the elevation of serum progesterone by 2 h in vehicle-treated controls and prevented the decline in progesterone levels in hydroxyflutamide-treated rats. The patterns of change in ovarian tissue concentrations with time and treatment were essentially similar to those observed for serum progesterone. In in vitro experiments, progesterone secretion during 24 h culture of preovulatory follicles obtained on PMSG-induced proestrus was significantly increased, sixfold, by addition to the culture media of 370 microM but not of 37 microM hydroxyflutamide. Testosterone (50 nM) and hCG (20 mIU/mL) caused 26- and 14-fold increases, respectively, in progesterone secretion by cultured follicles. Hydroxyflutamide significantly reduced the stimulatory effect of testosterone but not of hCG on progesterone secretion in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Testosterone increases thromboxane A2 receptors in cultured rat aortic smooth muscle cells

Previous studies have demonstrated increased contractile responses to thromboxane A2 (TXA2) mimetics in aortas obtained from male rats compared with those obtained from females. This study was designed to determine the effects of testosterone and 17 beta-estradiol treatment on TXA2 receptors in cultured rat aortic smooth muscle cells (RASMCs). TXA2 receptor affinity and density were determined through equilibrium binding experiments using the TXA2/prostaglandin H2 mimetic [1S-(1 alpha,2 beta(5Z),3 alpha(1E,3R*),4 alpha)]-7-[3-(3- hydroxy-4-(4'-125iodophenoxy)-1-butenyl)-7-oxabicyclo[2.2.1]hep tan-2-yl]- 5-heptenoic acid (125I-BOP). Incubation with testosterone (100 nM) for 24 or 48 hours resulted in a significant (p less than 0.05) 31% and 48% increase in TXA2 receptor density without any change in affinity. 17 beta-Estradiol (100 nM) had no significant effect on either the density or affinity of TXA2 receptors. Coincubation with the testosterone receptor antagonist hydroxyflutamide (1 microM) blocked the testosterone-induced increase in TXA2 receptor density. The maximum increase in intracellular free calcium induced by I-BOP was significantly (p less than 0.05) greater in testosterone-treated RASMCs than controls. Similarly, increases in inositol trisphosphate induced by the TXA2/prostaglandin H2 mimetic U46619 were significantly (p less than 0.05) greater in testosterone-treated RASMCs compared with controls. The results demonstrate that testosterone increases vascular TXA2 receptor density and support the notion that sex steroid hormones modulate the expression of this receptor.

Effects of flutamide and hydroxy-flutamide on the growth of human benign prostatic hyperplasia cells in primary culture: a preliminary report

Tissues from human benign prostatic hyperplasia [BPH] were collected from twelve patients undergoing routine transurethral resection of the prostate to relieve urine out-flow obstruction. Viable epithelial organoids were obtained after enzymatic digestion of the tissue. Primary cultures of epithelium were successfully maintained on collagen gel for up to 21 days. Immunocytochemical staining revealed that there was no expression of either desmin or vimentin in these cells; however, the anticytokeratin antibodies LP-34 (cytokeratins 4, 5, 6, 10, 13, 16, 17 and 18), LE-61 (cytokeratin 18) and CAM 5.2 (cytokeratins 7 and 8) all showed positive responses, indicating the epithelial nature of the cells. Cell growth was significantly increased in the presence of 3 x 10(-10) M testosterone propionate [TP] in the culture medium. The presence of the non-steroidal anti-androgens, Flutamide and Hydroxy-Flutamide [Flu-OH], in the concentration range 1.0-0.001 micrograms per ml of medium inhibited the growth in the presence of androgens in a dose-dependent manner. The anti-androgens failed to affect cell growth in the absence of TP. In view of these preliminary findings, it is postulated that the antiandrogens might be acting either by displacing the androgen from its receptor or alternately by inhibiting the activity of prostatic 5 alpha-reductase.

Effects of steroidal and non-steroidal antiandrogens on the androgen binding properties of the rat ventral prostate androgen receptor

Steroidal (cyproterone acetate) and non-steroidal (RU23908 and hydroxyflutamide) antiandrogens are able to block testosterone-induced increases in nuclear androgen receptor (AR) in the prostate of 1-day orchidectomized rats, but when given alone, RU23908 and hydroxyflutamide increase nuclear AR (RU23908 greater than hydroxyflutamide) in the same animal model. The increases in nuclear AR induced by antiandrogen alone or with testosterone alone are blocked by cycloheximide 1 h after administration, suggesting that androgen or antiandrogens induce de novo AR synthesis. Concomitant to nuclear AR accumulation, testosterone is able to induce depletion of cytosol and microsomal AR. Blockade of testosterone-induced depletion of microsomal AR, but not of cytosol AR, occurs in the presence of antiandrogens. Cyproterone acetate has a higher relative binding affinity (RBA) for microsomal AR and cytosol AR than RU23908 or hydroxyflutamide. This phenomenon is in good agreement with the degree of inhibition by these compounds of the association rate of androgen for the microsomal AR. This correlation between RBA and inhibition of the initial rate of hormone binding to the receptor is not found for cytosol AR. The results show that antiandrogens are not 'pure' antagonists of androgen action and they are potent agonists in the absence of testosterone. Furthermore, testosterone alone or antiandrogens per se regulate AR levels acutely by protein-synthesis dependent mechanisms of action, in rat ventral prostate.

Regulation of uterine progesterone receptors by the nonsteroidal anti-androgen hydroxyflutamide

We have recently reported that the anti-androgen hydroxyflutamide causes delayed implantation and exhibits antideciduogenic activity in the rat. The present experiments were conducted to examine whether hydroxyflutamide binds to the uterine progesterone receptors and/or alters the progesterone binding sites in the uterus. Cytosol and nuclear fractions from decidualized rat uterus were incubated with [3H]-R5020 without or with increasing concentrations of radioinert R5020, RU486, dihydrotestosterone, or hydroxyflutamide. From the log-dose inhibition curves, the relative binding affinity of both hydroxyflutamide and dihydrotestosterone was less than 0.1% and 2%, compared with R5020 (100%) for displacing [3H]-R5020 bound to uterine cytosol and nuclear fractions, respectively. Injection of estradiol-17 beta (1 microgram/rat) to ovariectomized prepubertal rats induced a 1.85-fold increase in uterine weight by 24 h. Hydroxyflutamide at 2.5 or 5.0 mg did not significantly alter the estrogen-induced increase in uterine weight. Compared to vehicle alone, estrogen induced an approximately 5-fold increase in uterine cytosolic progesterone binding sites. Hydroxyflutamide at both 2.5- and 5.0-mg doses significantly attenuated the estrogen-induced elevation in uterine progesterone binding sites. These studies demonstrate that hydroxyflutamide does not bind with high affinity to progesterone receptors, but suppresses the estrogen-induced elevation in progesterone receptor levels in the uterus.

Muscle as the primary site for testosterone to promote survival of axotomized motoneurons

Whether the effect of testosterone to promote neuronal survival is expressed through its interaction with motoneurons or with effector muscles was investigated, since androgen receptors are present in both tissues. Following unilateral transection of the hypoglossal and facial nerves, hydroxyflutamide, an androgen receptor antagonist, was injected into the tongue muscles to block androgen receptor binding during the period when rats were treated with testosterone. The results indicate that hydroxyflutamide abolished testosterone effects on the hypoglossal but not the facial motor nucleus, indicating that androgen receptors in effector muscles are the primary mediators of hormonal actions. We postulate that testosterone may play a role in the production of muscle-derived factors which promote the survival of injured motoneurons.

Effects of hydroxyflutamide on rats treated with a superovulatory dose of pregnant mare serum gonadotropin

Immature female rats treated with superovulatory doses of pregnant mare serum gonadotropin (PMSG) were used to study the effects of the antiandrogen hydroxyflutamide on steroid production, particularly the biologically active androgens, in two experiments. In the first experiment, animals were given either 5 mg hydroxyflutamide or vehicle alone at 30 and 36 h following 40 IU PMSG. Compared with the vehicle group, hydroxyflutamide treatment significantly reduced the percentage of degenerate oocytes recovered from oviducts (p less than 0.05). Serum levels of testosterone and androstenedione, and their aromatized product 17 beta-estradiol, significantly decreased (p less than 0.05) in the hydroxyflutamide-treated group; however, nonaromatizable androgen, 5 alpha-dihydrotestosterone, was not affected. In the second experiment, ovaries obtained 48 h after stimulation with 4 or 40 IU PMSG were incubated with and without hydroxyflutamide (10(-5) M) and (or) testosterone (10(-7) M) to study [4-14C]pregnenolone metabolism to major steroids. In 40 IU stimulated ovaries, hydroxyflutamide significantly decreased the metabolism of pregnenolone to progesterone (p less than 0.01) and androstenedione (p less than 0.01), while the production of 17 beta-estradiol increased significantly (p less than 0.05); however, pregnenolone conversions to testosterone and 5 alpha-dihydrotestosterone were not affected. Testosterone completely reversed the hydroxyflutamide-induced alteration of pregnenolone metabolism. In contrast, there was no difference in the pregnenolone conversion patterns between untreated and hydroxyflutamide or hydroxyflutamide plus testosterone groups in 4 IU stimulated ovaries. Present results confirm our previous finding that hydroxyflutamide decreases the percentage of abnormal oocytes recovered from superovulating rats and indicates that this hydroxyflutamide effect may be partly mediated by altered ovarian steroidogenesis following inhibition of androgen binding in the ovary.

Steady-state hydroxyflutamide plasma levels after the administration of two dosage forms of flutamide

A bioavailability study of randomized cross-over design was carried out in eight volunteers who were given a 48-h flutamide treatment consisting of 250-mg tablets three times daily or 400-mg sustained-release tablets twice daily, followed 3 weeks later by the alternative dosage form. Just before the last dose and 15 times during the subsequent 24 h, blood samples were obtained for the determination of plasma hydroxyflutamide (the active metabolite of flutamide) levels by high-performance liquid chromatography. No statistically significant differences between the two dosage forms were found for the lag time, rate of initial increase in concentration, peak plasma concentration, mean hydroxyflutamide concentration within one dosing interval or 24-h AUC value. One subject presented mild and transient nausea during both treatment periods. After the first treatment period (250-mg tablets), an increase in serum bilirubin was observed in another volunteer, who was withdrawn from the study. It may be concluded that both dosage forms were bioequivalent.

Evaluation of drug-induced prostatic involution in dogs by transabdominal B-mode ultrasonography

The relative antiandrogen-induced prostate involution activity of the newly synthesized hydroxyflutamide pro-drug was compared with that of flutamide in 25 Beagles. Secondary antiandrogen activity of both drugs on the testes and mammary tissue was investigated. Daily oral administration of both compounds at 2 dosages (ie, 2.5 and 5.0 mg/kg of body weight) during a 7-week period was monitored by transabdominal ultrasonography of the prostate twice a week. Cross-sectional area estimates of the prostate gland calculated from oblique dorsoventral, and transverse sonographic measurements were diminished significantly in some of the treated dogs as early as day 14 of drug administration. All treated dogs had significant differences in reduction by day 47. Involution was related directly to dose (P less than 0.05), but no difference was observed between test compounds. Differences in secondary antiandrogen activity were not remarkable. Flutamide was not found to have any activity advantage in vivo over hydroxyflutamide. It was concluded that ultrasonography can be a highly effective means of monitoring prostate size, and of monitoring drug-induced involution over time.

Opposite effects of estrogen and the progestin R5020 on cell proliferation and GCDFP-15 expression in ZR-75-1 human breast cancer cells

We have recently demonstrated that physiological concentrations of androgens caused a marked inhibition of basal and 17 beta-estradiol (E2)-induced cell growth in ZR-75-1 human breast cancer cells. Moreover, these steroids exert effects on GCDFP-15 (gross cystic disease fluid protein-15) expression that are opposite to their above-indicated actions on cell proliferation. The synthetic progestin R5020 (17.21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione), on the other hand, causes a potent inhibition of E2-induced ZR-75-1 cell growth. In order to further characterize the hormonal regulation of GCDFP-15 expression and to better understand the antagonism between progestin and estrogen action in breast cancer cells, we have studied the effect of R5020 on both GCDFP-15 expression and cell growth in ZR-75-1 cells. After a 10-day incubation, the 4-fold stimulatory effect of 1 nM E2 on cell growth was 60% decreased by maximal effective concentrations of R5020 (greater than 1 nM) while, in the absence of E2, R5020 had no effect. The mitogenic action of E2 was accompanied by a 75% inhibition of GCDFP-15 secretion while nanomolar concentrations of R5020 induced 1.4- and 5.2-fold increases in GCDFP-15 secretion in control and E2-treated ZR-75-1 cells, respectively. While E2 caused a marked inhibition of GCDFP-15 mRNA levels, R5020 induced a maximal 2- to 3-fold increase (above control) in GCDFP-15 mRNA accumulation in cells simultaneously incubated with E2.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of progesterone-binding breast cyst protein GCDFP-24 secretion by estrogens and androgens in human breast cancer cells: a new marker of steroid action in breast cancer

We have previously demonstrated that androgens are potent inhibitors of breast cancer cell proliferation under both basal and estrogen-induced incubation conditions, while they suppress expression of the estrogen and progesterone receptors. To better understand the mechanisms responsible for the antagonism between androgens and estrogens in breast cancer and to obtain a new tumor marker for the actions of these two steroids, we have investigated the effects of androgens and estrogens on expression of the major protein found in human breast gross cystic disease fluid, namely GCDFP-24. This study was performed in ZR-75-1 and MCF-7 human breast cancer cells. After a 9-day incubation period, physiological concentrations of 17 beta-estradiol stimulated proliferation of ZR-75-1 and MCF-7 cells by 2- to 3.5-fold while simultaneously exerting a marked 70-90% inhibition of GCDFP-24 secretion. The estrogenic effects on GCDFP-24 secretion and cell proliferation were both competitively blocked by simultaneous incubation with the new steroidal pure antiestrogen EM-139. On the other hand, a maximal concentration (10 nM) of the nonaromatizable androgen dihydrotestosterone decreased by 50% the proliferation of ZR-75-1 cells; the half-maximal inhibitory effect was exerted at 0.01 nM. The androgen exerted a 3- to 4-fold stimulatory effect on GCDFP-24 secretion at an EC50 value of 0.01 nM. The effect of dihydrotestosterone on these parameters was competitively blocked by simultaneous incubation with the pure antiandrogen OH-flutamide. The present data show that the effects of estrogens and androgens in ZR-75-1 cells on GCDFP-24 secretion and cell growth are opposite. Similarly, in MCF-7 cells, estrogens stimulate cell growth, while GCDFP-24 secretion is inhibited. The present data also suggest that GCDFP-24 could well be a good biochemical marker for monitoring the response to androgenic and antiestrogenic compounds in the therapy of advanced breast cancer.

Feedback control of gonadotropin secretion in mammalian and human males: effects of gonadotropin receptor blockers

Non-steroidal antiandrogens (NAA), flutamide and hydroxy-flutamide were used to study involvement of androgenic receptors in feedback control of gonadotropin secretion in males. In castrated animals these blockers inhibited the uptake of tritiated testosterone (T) by the hypothalamus and adenohypophysis. In male rats with intact gonads the NAA were found to reduce inhibitory effects of circulating endogenous androgens on the hypothalamus and pituitary gland which resulted in the increase of plasma LH, FSH and T levels, enhanced pituitary sensitivity to intravenously injected LHRH, increased activity of testicular steroid-delta 5-3 beta-ol-dehydrogenase. Endocrine response appeared the most pronounced in rats and was less marked in other animals species, and also in humans. No response was revealed in hypophysectomized male rats. Deafferentation of mediobasal hypothalamus by Halász knife had no impact on increased plasma T level following exposure to NAA. Furthermore, electrolytic destruction of arcuate nucleus and median eminence prevented or diminished significantly stimulation of LH, FSH and T secretion in NAA treated male rats. The results of this study suggest that androgenic receptors of mediobasal hypothalamus and pituitary gland are involved in control of gonadotropin secretion by circulating male sex hormones.

The proliferative effect of "anti-androgens" on the androgen-sensitive human prostate tumor cell line LNCaP

The effect of steroidal and nonsteroidal "anti-androgens" on the proliferative capacity of androgen-sensitive LNCaP-FGC human prostate tumor cells in culture was studied using charcoal-dextran stripped human serum-supplemented media. Cyproterone and medroxyprogesterone acetates, flutamide, hydroxyflutamide, and anandron (R23908) were administered alone at concentrations between 3 X 10(-12) and 3 X 10(-6) M. Results indicated that although medroxyprogesterone induced maximal proliferation at 3 X 10(-9) M, the other "anti-androgens" (with the exception of flutamide that was ineffective) were effective at 3 X 10(-8) M and higher concentrations; the amplitude of the proliferative response by these compounds was comparable to that elicited by estradiol-17 beta (3 to 5-fold over control). None of the anti-androgens tested triggered the shutoff effect characteristic of androgen action. When 3 X 10(-10) M DHT and the above mentioned anti-androgens were administered simultaneously, a synergistic pattern was seen; on the contrary, 3 X 10(-8) M DHT cancelled the proliferative effect of each of the anti-androgens when administered simultaneously. The relative binding affinity of these anti-androgens to androgen receptors present in LNCaP-FGC cells did not correlate well with their proliferative efficiency. The data collected were interpreted within the premises of the negative control hypotheses for the regulation of cell proliferation in metazoans. Within those premises, results became compatible with the notion that first, "anti-androgens" elicited the proliferation of androgen-sensitive cells by neutralizing the effect of a serum-borne inhibitor (androcolyone-I); this event seems not to be mediated by androgens receptors. Second, anti-androgens did not trigger a proliferative shutoff response like androgens do, i.e. the proliferative pattern induced by anti-androgens was comparable to that elicited by estrogens and progestins. Third, when administered simultaneously with 3 X 10(-10) M DHT, anti-androgens behaved synergistically. Fourth, the DHT-induced shutoff effect consistently overrode the proliferative effect generated by anti-androgens and estrogens when added alone. Finally, taken together these results raise important questions regarding the therapeutic role of anti-androgens in prostate cancer.

Implantation delay and anti-deciduogenic activity in the rat by the anti-androgen, hydroxyflutamide

Studies were undertaken to determine whether the anti-androgen, hydroxyflutamide, has anti-progestagenic activity by using implantation, maintenance of pregnancy, and decidualization as end points. Prepubertal rats were induced to ovulate with the injection of 4 IU pregnant mare's serum gonadotropin and allowed to mate. Mated females were assigned randomly to various treatment groups. Beginning at 0800 h on Day 4 of pregnancy and at 12-h intervals thereafter, rats received a series of 6 s.c. injections of 5 mg hydroxyflutamide in oil, or oil only. Localized changes in endometrial vascular permeability, indicative of implantation, were assessed on Days 6 and 8 of pregnancy, after an injection of Evans blue dye. By Day 6, implantation has been initiated in the vehicle-treated rats, but not in hydroxyflutamide-treated rats. Hydroxyflutamide treatment was terminated on Day 6, and implantation was initiated by Day 8. The weights of uterine dye sites in hydroxyflutamide-treated rats on Day 8 were similar to those in vehicle-treated rats on Day 6. The number of fetuses and placentae were similar in all groups on Day 19. The weights of fetuses in both hydroxyflutamide-treated and hydroxyflutamide + progesterone-treated rats were similar and significantly lower than those in control rats. Although there were no significant differences between vehicle-treated or hydroxyflutamide-treated rats in the proportion of rats delivering and litter size, the hydroxyflutamide-treated rats delivered pups a mean of one day later than did the controls. Endometrial decidualization in ovariectomized, steroid-treated rats, following artificial stimuli, was significantly suppressed in hydroxyflutamide-treated rats compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Single and multiple dose pharmacokinetic evaluation of flutamide in normal geriatric volunteers

Single dose and steady-state pharmacokinetics of flutamide (F) and its active plasma metabolite, hydroxyflutamide (HF) were studied in twelve healthy geriatric volunteers administered 250 mg flutamide capsules on day 1 and 250 mg flutamide capsules three times a day on days 2 through 9. After oral administration, F was rapidly absorbed and metabolized. It was present in the plasma in small and variable concentrations, which precluded quantitative assessment of pharmacokinetic parameters for individual subjects. Steady-state plasma concentrations were reached on or before Day 6. The mean steady state Cmax (Day 9), 112.7 ng/ml, occurred at 1.3 hr. Pharmacokinetic analysis of mean data at steady-state gave a distribution and elimination half-life of 0.8 hr and 7.8 hours, respectively. The plasma levels for HF were much higher and less variable than F. The mean Cmax for HF averaged 894 ng/ml at 2.7 hours after a single dose and 1719 ng/ml (Day 9) at 1.9 hr after multiple doses. The distribution and elimination half-lives of HF at steady-state were 1.9 and 9.6 hours, respectively. The steady-state HF plasma concentrations were also achieved on or before Day 6 and were approximately twice those obtained after a single dose. From this study, it has been demonstrated that the pharmacokinetics of F and HF do not change appreciably upon multiple dosing of 250 mg F capsule given three times a day.

Androgens directly stimulate proliferation of bone cells in vitro

This report describes the first observation of a direct mitogenic effect of androgens on isolated osteoblastic cells in serum-free culture. [3H]thymidine incorporation into DNA and cell counts were used as measures of cell proliferation. The percentage of cells that stained for alkaline phosphatase was used as a measure of differentiation. Dihydrotestosterone (DHT) enhanced mouse osteoblastic cell proliferation in a dose dependent manner over a wide range of doses (10(-8) to 10(-11) molar), and was maximally active at 10(-9) M. DHT also stimulated proliferation in human osteoblast cell cultures and in cultures of the human osteosarcoma cell line, TE89. Testosterone, fluoxymesterone (a synthetic androgenic steroid) and methenolone (an anabolic steroid) were also mitogenic in the mouse bone cell system. The mitogenic effect of DHT on bone cells was inhibited by antiandrogens (hydroxyflutamide and cyproterone acetate) which compete for binding to the androgen receptor. In addition to effects on cell proliferation, DHT increased the percentage of alkaline phosphatase (ALP) positive cells in all three bone cell systems tested, and this effect was inhibited by antiandrogens. We conclude that androgens can stimulate human and murine osteoblastic cell proliferation in vitro, and induce expression of the osteoblast-line differentiation marker ALP, presumably by an androgen receptor mediated mechanism.

Ability of progesterone to reverse anti-androgen (hydroxyflutamide)-induced interference with the preovulatory LH surge and ovulation in PMSG-primed immature rats

In Exp. 1, PMSG was injected to 26-day-old prepubertal rats to induce ovulations. On Day 2 (2 days later, the equivalent of the day of pro-oestrus) they received at 08:00 h 5 mg hydroxyflutamide or vehicle and at 12:00 h 2 mg progesterone or testosterone or vehicle. Animals were killed at 18:00 h on Day 2 or at 09:00 h on Day 3. Progesterone but not testosterone restored the preovulatory LH surge and ovulation in hydroxyflutamide-treated rats. In Exp. 2, 2 mg progesterone or testosterone were injected between 10:30 and 11:00 h on Day 2, to advance the pro-oestrous LH surge and ovulation in PMSG-primed prepubertal rats. Injection of hydroxyflutamide abolished the ability of progesterone to advance the LH surge or ovulation. Testosterone did not induce the advancement of LH surge or ovulation. In Exp. 3, ovariectomized prepubertal rats implanted with oestradiol-17 beta showed significantly (P less than 0.01) elevated serum LH concentrations at 18:00 h over those observed at 10:00 h. Progesterone injection to these animals further elevated the serum LH concentrations at 18:00 h, in a dose-dependent manner, with maximal values resulting from 1 mg progesterone. Hydroxyflutamide treatment significantly (P less than 0.003) reduced the serum LH values in rats receiving 0-1 mg progesterone but 2 mg progesterone were able to overcome this inhibition. It is concluded that progesterone but not testosterone can reverse the effects of hydroxyflutamide on the preovulatory LH surge and ovulation. It appears that hydroxyflutamide may interfere with progesterone action in induction of the LH surge, suggesting a hitherto undescribed anti-progestagenic action of hydroxyflutamide.

Androgenic activity of synthetic progestins and spironolactone in androgen-sensitive mouse mammary carcinoma (Shionogi) cells in culture

A series of compounds designed to block the action of androgens in target tissues, and called antiandrogens, have been developed for the treatment of androgen-sensitive diseases, especially prostate cancer, hirsutism, precocious puberty and deviant sexual behavior. In order to further assess the androgenic activity of these compounds, we have studied their effect on the growth of an androgen-sensitive clone of the mouse mammary carcinoma Shionogi SC-115 cells in culture. Hydroxy-flutamide did not affect the doubling time (7.40 +/- 0.09 vs 7.20 +/- 0.12 days) characteristic of these cells. However, all of the other compounds tested stimulated cell growth. Thus, in the presence of cyproterone acetate, cells had an accelerated growth rate and shorter generation time of 6.28 +/- 0.06 days (P less than 0.01). In the presence of 1 microM spironolactone, the generation time was 4.96 +/- 0.04 days (P less than 0.01). With chlormadinone acetate, the doubling time was reduced to 3.79 +/- 0.08 days while for megestrol acetate, the doubling time was 3.63 +/- 0.04 days (P less than 0.01). The synthetic progestin Medroxyprogesterone acetate had the most potent androgenic effect reducing the doubling time to 1.85 +/- 0.05 days (P less than 0.01). For comparison, dihydrotestosterone gave a doubling time of 1.76 +/- 0.07 days. When hydroxy-flutamide (5 microM) was added simultaneously with each "progestin", the ED50 value of action of all the compounds was increased in a competitive manner, thus indicating that the mitogenic effect on cell growth of all compounds is mediated by the androgen receptor. Of all the compounds used, only hydroxy-Flutamide was devoid of any androgenic activity and thus meets the criteria of a pure antiandrogen.

Androgens inhibit basal and estrogen-induced cell proliferation in the ZR-75-1 human breast cancer cell line

This study describes the inhibitory effect of 5 alpha-dihydrotestosterone (5 alpha-DHT) and its precursors testosterone (T) and androst-4-ene-3,17-dione (delta 4-DIONE) on the growth of the estrogen-sensitive human breast cancer cell line ZR-75-1. In the absence of estrogens, cell proliferation measured after a 12-day incubation period was 50-60% inhibited by maximal concentrations of 5 alpha-DHT, T, or delta 4-DIONE with half-maximal effects (IC50 values) observed at 0.10, 0.15 and 15 nM, respectively. This growth inhibition by androgens was due to an increase in generation time and a lowering of the saturation density of cell cultures. The antiestrogen LY156758 (300 nM) induced 25-30% inhibition of basal cell growth, its effect being additive to that of 5 alpha-DHT. The mitogenic effect of 1 nM estradiol (E2) was completely inhibited by increasing concentrations of 5 alpha-DHT with a potency (IC50 = 0.10 nM) similar to that measured when the androgen was used alone. E2 had a more rapid effect on cell proliferation than 5 alpha-DHT, the latter requiring at least 5 to 6 days to exert significant growth inhibition. As found in the absence of estrogens, maximal inhibition of cell proliferation in the presence of E2 was achieved by the combination of the antiestrogen and 5 alpha-DHT. Supraphysiological concentrations of E2 (up to 1 microM) were needed to completely reverse the growth inhibitory effect of a submaximal concentration of 5 alpha-DHT (1 nM). The antiproliferative effect of androgens was competitively reversed by the antiandrogen hydroxyflutamide, thus indicating an androgen receptor-mediated mechanism. The present data suggest the potential benefits of an androgen-antiestrogen combination therapy in the endocrine management of breast cancer.

Testosterone suppression of ornithine decarboxylase activity in rat Sertoli cells

The effect of testosterone on the induction of Sertoli cell ornithine decarboxylase (ODC) activity was investigated in highly purified cultures derived from testes of 20-day-old rats. Sertoli cell cultures were maintained in serum-free Ham's F-10 medium, with refeeding on days 2 and 4. Before refeeding on day 4, ODC activity was 7.4 U (1 U = 1 pmol 14CO2 released/mg protein.60 min at 37 C). After a medium change, ODC activity increased (41.6 U at 10 h; 180.0 U at 24 h) and then returned to near-basal activity (26.3 U) after 48 h. Simultaneous addition of testosterone (150 ng/ml; 5.2 X 10(-7) M) with the day 4 medium change suppressed the increase in ODC induction (7.53 U at 10 h, 91.6 U at 24 h). Addition of testosterone 24 h before refeeding resulted in greater inhibition of ODC induction (6.9 U at 10 h; 45.4 U at 24 h) than when added simultaneously. Other androgens, 5 alpha-dihydrotestosterone, androsterone, and 5 alpha-androstane-3 alpha,17 beta-diol, also suppressed induction of ODC, whereas 17 beta-estradiol was ineffective, illustrating the steroid specificity of the effect. Coadministration of the antiandrogens hydroxyflutamide or cyproterone acetate partially blocked the testosterone effect. Induction of ODC activity by ovine FSH (10 ng/ml) was also suppressed when Sertoli cells were cultured in the presence of testosterone (150 ng/ml) from the time of isolation. However, induction of ODC activity by (BU)2cAMP was uncompromised by testosterone. These results suggest that testosterone may repress ODC activity and, hence, polyamine biosynthesis in the Sertoli cell, but that cAMP, acting through the trophic hormone FSH, can overcome this suppression of putrescine biosynthesis. Intratesticular and hypophyseal modulation of polyamine biosynthesis may influence not only cellular processes in the Sertoli cell itself but also its role in spermatogenesis.

Human chorionic gonadotropin and luteinizing hormone-releasing hormone reverse the blockade of ovulation in pregnant mare's serum gonadotropin-primed immature rats by the anti-androgenic drug, hydroxyflutamide

The present study was designed to examine mechanism(s) of the anti-ovulatory action of the anti-androgen, hydroxyflutamide (OH-F). Prepubertal rats were treated with 4 IU pregnant mare's serum gonadotropin (PMSG) (day -2) to induce first estrus and ovulation. They received OH-F in sesame oil or oil alone at 08:00 and 20:00 h on day 0 (the day of proestrus) and ovulations were assessed on the morning of day 1. Eighty-three percent of control animals ovulated with a mean of 7.7 +/- 1.1 corpora lutea per rat. Hydroxyflutamide blocked ovulation in all but 2 of the 12 rats receiving this drug alone. All of OH-F treated rats that received 5 and 25 IU human chorionic gonadotropin (hCG) ovulated with means +/- SEM of 9.1 +/- 0.1 and 7.3 +/- 1.4 corpora lutea per rat, respectively. The dose of 0.2 IU hCG was essentially ineffective, while the effect of 1.0 IU hCG was intermediate. At the dose of 20 ng and above (100 and 500 ng) luteining hormone-releasing hormone (LHRH) completely overcame the ovulation blockade in the OH-F treated animals, while a 4-ng dose was ineffective. At 18:00 h on the day of proestrus, serum LH levels in control animals were 17.56 +/- 2.60 ng/mL, which were 920% above basal levels (1.90 +/- 0.13) indicating a spontaneous LH surge. This surge was suppressed in OH-F treated rats. Injection of LHRH, at the dose of 20 ng and above, reinstated the LH release in OH-F treated animals. Thus, the anti-androgen, OH-F, inhibits ovulation in PMSG-treated immature rats through its interference with the preovulatory LH surge; the inhibition can be reversed by hCG or LHRH. Hydroxyflutamide does not appear to interfere at the level of the pituitary, but may have direct action at the hypothalamic and (or) extrahypothalamic sites involved in the generation of positive feedback signals that control LH release.

Comparative effects of androgens and catecholestrogens on progesterone production by porcine granulosa cells

The objective of the present studies was to evaluate and compare the effects of 5 alpha-dihydrotestosterone (DHT) to those of 2-hydroxyestradiol (2-OH-E2) and 2-methoxyestradiol (2-MeO-E2) on progesterone production in cultured porcine granulosa cells. Granulosa cells were exposed to various treatments of DHT, 2-OH-E2 and 2-MeO-E2 in the absence or presence of follicle stimulating hormone (FSH) for 4 days and concentrations of progesterone in medium and cell numbers were determined. In the absence of FSH, maximally effective concentrations of DHT (1 micrograms/ml) and 2-OH-E2 (4 micrograms/ml) stimulated progesterone production (ng/10(5) cells/48 h) to 2.2 +/- 0.2- and 10.8 +/- 2.2-fold of controls (n = 4 experiments), respectively. In the presence of 200 ng/ml FSH, progesterone production stimulated by 1 micrograms/ml DHT and 4 micrograms/ml 2-OH-E2 was 5.4 +/- 1.1- and 15.5 +/- 6.0-fold of controls (n = 4 experiments), respectively. Thus, FSH appeared to enhance the response of both DHT and 2-OH-E2. The dose-response of DHT was biphasic in the presence and absence of FSH, such that progesterone production in the presence of 8 micrograms/ml DHT was similar to basal progesterone production. Concurrent treatment with saturating concentrations of 2-OH-E2 and DHT resulted in fully additive increases in progesterone production. Testosterone mimicked the effect of DHT. In comparison, concurrent treatment of saturating concentrations of 2-MeO-E2 and DHT or 2-MeO-E2 and 2-OH-E2 resulted in progesterone production that was only partially additive.(ABSTRACT TRUNCATED AT 250 WORDS)

[Nonsteroidal antiandrogen inhibition of testosterone metabolism in the prostate]

The effect of prolonged administration of antiandrogen flutamide (FT) on testosterone (T) metabolism in the prostate (P) of intact and castrated rats and animals receiving androgens with substitution purpose was studied. In intact animals the production of dehydrotestosterone from labeled T in vitro was decreased in 30 days by 50%. The influence of FT on 5 alpha-reductase was shown to be determined by the blockade of androgenic effects. Proceeding from the results of experiments with FT and its hydroxylated metabolite added to incubated homogenates of the prostate of intact animals it was assumed that FT hydroxylated metabolite mediated FT influence on T metabolism.

The pharmacokinetics of flutamide and its major metabolites after a single oral dose and during chronic treatment

Flutamide is a nonsteroidal antiandrogen used in the treatment of prostatic carcinoma. We have investigated the disposition of flutamide and its two major metabolites in ten urological in-patients without significant liver or renal disease. After oral administration flutamide is absorbed from the gastrointestinal tract with a tmax of about 2 h. Flutamide undergoes extensive first-pass metabolism, and its major metabolites are 2-hydroxyflutamide and the hydrolysis product 3-trifluoromethyl-4-nitroaniline. After the oral administration of a single dose of 250 mg or 500 mg maximum flutamide plasma concentrations of 0.02 and 0.1 micrograms.ml-1 respectively were observed. Maximum plasma concentrations of 2-hydroxyflutamide for the same flutamide doses were 1.3 and 2.4 micrograms.ml-1 (mean of n = 2 or n = 3). Steady-state concentrations of the biologically active metabolite 2-hydroxyflutamide (0.94 +/- 0.23 micrograms.ml-1, mean +/- SD, n = 5) were found at 2-4 days after the administration of 250 mg every 8 h. The area under the plasma concentration time curve for 2-hydroxyflutamide averaged 11.4 (10.6 and 12.1) and 24.3 (21.5-29.4, n = 3) micrograms.ml-1.h for 250 mg and 500 mg flutamide orally. 2-Hydroxyflutamide and 3-trifluoromethyl-4-nitroaniline were eliminated monoexponentially with half-times of 4.3-21.9 and 4.3-17.2 h (n = 5) respectively.

Plasma levels of hydroxy-flutamide in patients with prostatic cancer receiving the combined hormonal therapy: an LHRH agonist and flutamide

The present study describes a method for the measurement of the plasma levels of hydroxy-flutamide (Flu-OH), the biologically active and main circulating metabolite of flutamide. We have observed that two to four hours after oral administration of 250 mg of flutamide to healthy young men, as well as to patients with prostate cancer, the plasma concentration of Flu-OH reaches a peak at approximately 1.7 microM. The plasma concentration of Flu-OH measured at months 6, 12, and 18 of treatment shows a minimal basal level of 3.4 microM with a maximal increase at 6.8 to 8.5 microM at 2 to 4 hours. Since the serum levels of testosterone in these patients are approximately 1 nM, the levels of the active antiandrogen are at a 5000- to 10000-fold excess. However, due to the low affinity of the antiandrogen for the androgen receptor, it is extremely important to maintain this concentration of the antiandrogen in plasma constant.

Inhibition of rat testicular 17 alpha-hydroxylase and 17,20-lyase activities by anti-androgens (flutamide, hydroxyflutamide, RU23908, cyproterone acetate) in vitro

Flutamide, hydroxyflutamide, RU23908 and cyproterone acetate (CPA) inhibited rat testicular microsomal 17 alpha-hydroxylase and 17,20-lyase activities in vitro. The Km of [3H] progesterone for 17 alpha-hydroxylase was 45 +/- 0.62 nmol/l (+/- SEM, n = 12) and the Km of [3H] 17 alpha-hydroxyprogesterone for 17,20-lyase was 192 +/- 0.42 nmol/l (+/- SEM, n = 12). The Ki values for 17 alpha-hydroxylase, determined from Lineweaver-Burk plots were 102 +/- 3.2 mumol/l (+/- SEM, n = 6), 363 +/- 3.8 mumol/l (+/- SEM, n = 6), 118 +/- 1.4 mumol/l (+/- SEM, n = 6) and 123 +/- 2.1 mumol/l (+/- SEM, n = 6) for flutamide, hydroxyflutamide, RU23908 and CPA respectively. Flutamide and CPA were mixed-type inhibitors, whereas hydroxyflutamide and RU23908 were competitive inhibitors of 17 alpha-hydroxylase activity. Ki values for 17,20-lyase were 33 +/- 3.1 mumol/l (+/- SEM, n = 6), 112 +/- 3.1 mumol/l (+/- SEM, n = 6), 69 +/- 4.4 mumol/l (+/- SEM, n = 6) and 71 +/- 3.2 mumol/l (+/- SEM, n = 6) for flutamide, hydroxyflutamide, RU23908 and CPA, respectively. Inhibition was found to be competitive in each case. Although the characteristic action of anti-androgens is at the receptor level, these results demonstrate that anti-androgens may also have inhibitory effects on androgen biosynthesis which could prove to be of clinical significance.

Interference with the preovulatory luteinizing hormone surge and blockade of ovulation in immature pregnant mare's serum gonadotropin-primed rats with the anti-androgenic drug, hydroxyflutamide

The involvement of androgens in the control of ovulation has been assessed by administration of the androgen antagonist, hydroxyflutamide, to prepubertal rats treated with pregnant mare's serum gonadotropin (PMSG) to induce first estrus and ovulation. Without human chorionic gonadotropin (hCG) injection, only 46% of rats that received six 5-mg, s.c. injections of hydroxyflutamide at 12-h intervals, beginning an hour before s.c. injection of 4 IU PMSG on Day-2 (Day 0 = the day of proestrus), had ovulated a mean of 1.3 +/- 0.4 oocytes per rat when killed on the morning of Day 1, whereas 92% of sesame oil-treated controls had ovulated a mean of 6.9 +/- 0.6 oocytes. After i.p. injection of hCG at 1600 h on Day 0, 92% of hydroxyflutamide-treated rats ovulated a mean of 8.3 +/- 1.2 oocytes compared to 100% of controls, which ovulated 7.3 +/- 0.4 oocytes per rat: these groups were not significantly different from each other, nor from control rats that received no hCG. Thus, exogenous hCG completely overcame the inhibitory effect of hydroxyflutamide on ovulation. Rats treated with PMSG and hydroxyflutamide without hCG were killed either on the morning of Day 0 to determine serum and ovarian steroid levels or on the afternoon of Day 0 to determine serum LH levels. Serum levels of estradiol-17 beta and testosterone in hydroxyflutamide-treated rats were significantly higher (178% and 75%, respectively; p less than 0.01) than levels observed in controls on the morning of Day 0. Ovarian concentrations of the steroids were also elevated in hydroxyflutamide-treated rats (p less than 0.01 for testosterone only).(ABSTRACT TRUNCATED AT 250 WORDS)

Onset of steroidogenesis and differentiation of functional LH receptors in rat fetal testicular cultures

The present study was performed to investigate in vitro the onset of steroidogenesis and the responsiveness to LH in rat fetal testes. The male gonads explanted on days 12.5, 13.5, and 14.5 of gestation in M199 produced testosterone from 15.5 days as is the case in vivo dcAMP (1 mM) induced an anticipated steroidogenesis on day 14.5 with secretions of testosterone (0.026 +/- 0.003 ng/gonad/24 h) and progesterone (0.078 +/- 0.005 ng/gonad/24 h), whereas LH (100 ng/ml) has no effect. Antiandrogens such as aminoglutethimide (2 mM), cyproterone acetate (1 microgram/ml), and hydroxyflutamide (1 microgram/ml) could not delay the responsiveness to LH on day 15.5. An anticipated production of testosterone on day 14.5 in presence of DHA (200 ng/ml) could not induce functional LH receptors. It would appear that: (a) the onset of testosterone production occurs without extrinsic stimulatory factors; (b) dcAMP initiates an early steroidogenesis; (c) the onset of functional receptors is likely free of the androgenic environment.

Androgen dependence of the Dunning R3327G cell line in monolayer culture

For optimal application of new treatment strategies for prostate cancer, the basic biologic effects of androgens on cell kinetics and DNA synthesis require detailed examination. An androgen-responsive prostate cancer cell line in monolayer culture provides a means to study the biochemical mechanisms mediating hormonal stimulation of cell proliferation. We chose to evaluate the proliferative response of the Dunning R3327G tumor cell line (Du-G cells) to 5 alpha-dihydrotestosterone (DHT) in monolayer culture. The DU-G cells grew more rapidly in the presence of increasing concentrations of DHT in the range of 10(-8)-10(-5) M than with vehicle control. At 10(-7) M DHT, 3H-thymidine incorporation increased from 400 +/- 34 counts/min/well to 751 +/- 77 (p less than .01). Effects of DHT were maximal when a plating density of 10,000 cells/well was employed. Androgen effects on cellular growth were reproducible but were limited in magnitude. Rapid metabolism of DHT in culture did not explain this phenomenon. Du-G cells were not completely dependent on androgen, since cells continued to grow in media containing less than 10(-11) M dihydrotestosterone and hydroxyflutamide.

[Biochemical bases of the antifertility action of the nonsteroidal antiandrogen niphtolid]

The study was made of biosynthesis and levels of nucleic acids and proteins in the head of epididymis as well as of the fertility of intact mature male rats under antiandrogenic exposure to nonsteroid antiandrogenic compound niphtolid. Niphtolid given per os in a dose of 25 micrograms/kg during 8 or 30 days decreased the mass of the organ and its concentrations of DNA, RNA and proteins. The above mentioned alterations seemed to be caused by inhibited inclusion of labeled precursors into biopolymers. A long-term intake of antiandrogen (10 micrograms/kg of body mass daily for a six-months period) was followed by developing transient infertility. The possibility to use niphtolid-like compounds both alone and in combination with antigonadotrophic drugs for fertility regulation is assumed.

Endocrine-responsive pancreatic carcinoma: steroid binding and cytotoxicity studies in human tumor cell lines

We have begun to investigate the steroid responsiveness of pancreatic cancer by comparing human (MiaPaCa, Colo-357, RWP-1, RWP-2) and rodent (AR42j) pancreatic tumor cell lines with cultured estrogen receptor-positive breast cancer cells (MCF-7, T47-D). The four human pancreatic tumors contain measurable levels of specific estradiol binding sites with dissociation constants (Kd) that range from 1 to 9 nM, in contrast to the higher-affinity binding sites measured in the breast cancer cells (Kd less than or equal to 1 nM). Growth of one pancreatic tumor line (MiaPaCa) is stimulated 40% above control by exposure to nanomolar concentrations of estradiol, suggesting that the estrogen receptor in these cells is functioning like that in MCF-7 and T47-D cells. Glucocorticoids (dexamethasone, hydrocortisone) and androgen (fluoxymesterone) stimulate proliferation of Colo-357 cells by as much as 30%. Paradoxically, glucocorticoids inhibit AR42j cells to less than 50% of control growth. Micromolar exposures of estrogen (17 beta-estradiol), antiestrogen (tamoxifen), antiandrogen (dehydroxyflutamide), progestins (progesterone, R5020, medroxyprogesterone acetate), and inhibitors of steroid-metabolizing enzymes (17 beta-N,N-diethylcarbamyl-4-methyl-4-aza-5 alpha-androstan-3-one, danazol) impair growth of these pancreatic tumors to varying degrees, and with little relationship to estrogen receptor content. In general, progestins are slightly more growth inhibiting to these pancreatic tumor lines than the other endocrine agents tested, including tamoxifen. Only the RWP-2 cells appear completely resistant to steroidal therapy, showing less than 25% growth inhibition with exposure to therapeutic concentrations (less than or equal to 2.5 microM) of these agents. Colo-357, MiaPaCa, and AR42j cells are most responsive to these endocrine agents, and their overall pattern of sensitivity suggests that the steroid-dependent growth-inhibitory mechanisms of some pancreatic carcinomas may involve both receptor antagonism and direct inhibition of steroidal oxidoreductases. 17 beta-N,N-Diethylcarbamyl-4-methyl-4-aza-5 alpha-androstan-3-one, a potent inhibitor of 5 alpha-reductase with minimal affinity for androgen receptor, inhibits growth of Colo-357 cells to less than 40% of control and also inhibits AR42j and MiaPaCa cells. Dehydroxyflutamide, a potent androgen receptor antagonist with no direct influence on 5 alpha-reductase activity, inhibits growth of MiaPaCa and AR42j cells but has no affect on Colo-357 growth.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of cell nuclear androgen receptor binding and copulation in male rats by an antiandrogen, Sch 16423

The ability of the flutamide metabolite Sch 16423 to block androgen receptor binding and inhibit masculine copulatory behavior in male rats was examined. Restoration of copulatory behavior was prevented in Sch 16423-treated rats given two 10-mm testosterone (T)-filled Silastic capsules plus 15 mg Sch 16423 daily for 11 days. Control males receiving only T-filled capsules copulated successfully. To test maintenance of copulatory behavior, T-filled capsules were implanted at the time of castration and rats received daily injections of either 0, 1, 5, 15 or 30 mg Sch 16423. Ejaculation was not prevented by Sch 16423 treatment, suggesting only a weak effect of Sch 16423 on the maintenance of copulatory behavior. An exchange assay was used to determine the effects of Sch 16423 on cell nuclear androgen receptor binding both in vivo and in vitro. For in vivo tests, castrate males bearing two 10-mm T-filled capsules received a single injection of either 0, 1, 5, or 15 mg Sch 16423 1 h prior to sacrifice. Androgen receptor binding was drastically reduced in both brain (combined hypothalamus, preoptic area, amygdala and septum) and pituitary at all doses of Sch 16423. For in vitro assays, samples from brain and pituitary were incubated with 10(-10) to 10(-6) M dihydrotestosterone (DHT), Sch 16423 or flutamide. Sch 16423 competed for androgen receptors in vitro, though not as effectively as DHT. Flutamide was a poor competitor. These results indicate that Sch 16423 effectively reduces masculine copulatory potential primarily affecting restoration of behavior, and that Sch 16423 inhibited cell nuclear androgen receptor binding both in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypothalamic-pituitary function in experimental uremic hypogonadism

In companion studies we have shown that chronic uremic male rats are infertile and hypoandrogenic and have lowered basal LH levels. Fertility was restored by either human CG (hCG) or testosterone treatment. Testicular steroidogenic responses to hCG in vivo and in vitro were normal or excessive, indicating that hypothalamic-pituitary dysfunction was the predominant early lesion in uremic hypogonadism. Further studies were undertaken to characterize the nature of the central defects in regulation of pituitary LH secretion. Uremic rats have reduced MCRs for rat LH (rLH) (61%), rat FSH (rFSH) (47%), and LHRH (41%). Pituitary gonadotropin and hypothalamic LHRH content were unchanged in uremic rats. Pituitary rLH and rFSH responses to LHRH stimulation in vivo and in vitro were quantitatively normal or excessive, with delayed peaks suggesting that uremic pituitary gonadotrope secretion is deficient due to lack of appropriate hypothalamic LHRH drive rather than intrinsic pituitary defects. Despite reduced pituitary gonadotropin secretion in intact uremic rats, castration induced paradoxical excessive increases in pituitary LHRH binding, serum rLH, and rFSH beyond those of nonuremic controls. Paradoxical postcastration hyperresponses of serum rLH and rFSH were not due to circulating immunoreactive fragments of gonadotropins or undernutrition. Dysfunction of the uremic hypothalamus was further characterized in vivo by lack of rLH responsiveness to naloxone and hypersensitivity to negative testicular feedback in castrate-steroid-replaced and intact rats. These data demonstrate that uremic hypogonadism is principally due to aberrant hypothalamic regulation of pituitary LH secretion resembling those of the immature rat or seasonally regressed animal. This recrudescence of the inactive regulatory state in a disease model suggests that common mechanisms are operative in orderly gonadal withdrawal under hostile or inappropriate environments and may underly the reversibility of human uremic hypogonadism with successful renal transplantation.

Inhibition of 20 alpha-hydroxysteroid dehydrogenase activity by follicle-stimulating hormone and androgens in cultured rat granulosa cells: a search for the mechanism of action

Alterations of progesterone metabolism and especially of 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD) activity were studied in cultured rat granulosa cells following various treatments. The cells were incubated for up to 48 h with or without follicle-stimulating hormone (FSH), androgens, hydroxyflutamide, estrogens, chlorea toxin, and dibutyryl cAMP [Bu2 cAMP]. Subsequently, the cells were incubated for 3 h with [4-14 C] progesterone (0.5 microM). The progesterone utilization and accumulation of 20 alpha-reduced and 5 alpha-reduced metabolites were assessed following thin-layer chromatography separation of radiolabeled steroids. Both FSH (1 microgram/ml) and testosterone (0.5 microM) decreased the 20 alpha-HSD activity by decreasing the maximal velocity (by 52% and 37%, respectively) without changing significantly the Km value. The inhibition of 20 alpha-HSD was demonstrable following 12 and 24 h exposure to FSH and following 24 and 48 h exposure to testosterone. Effects comparable to that induced by testosterone were elicited by other androgens (androstenedione and 5 alpha-dihydrotestosterone), but not by estrogens (estradiol-17 beta and estrone). Hydroxyflutamide reversed testosterone-induced effects: the increase of endogenous progesterone accumulation and the decrease of 20 alpha-HSD activity. Both cholera toxin (0.001-10 micrograms/ml) and Bu2 cAMP (62.5-1000 micrograms/ml) caused a dose-dependent inhibition of 20 alpha-HSD activity. Present results indicate that: the inhibition of 20 alpha-HSD by both FSH and androgens may be of a noncompetitive nature; androgen action on 20 alpha-HSD may be a true androgenic, receptor-mediated effect; and cAMP may mediate the FSH action on 20 alpha-HSD activity.

Control of granulosa cell lactate production by follicle-stimulating hormone and androgen

Lactate accumulation in granulosa cell cultures (prepared from estrogen-pretreated immature rat ovaries) increased with human FSH (hFSH) concentration in the culture medium. In 48-h cultures, maximal stimulation (approximately 25%) occurred in the presence of more than or equal to 100 ng hFSH/ml. Human CG (hCG) (3-1000 ng/ml) had no effect. Testosterone and 5 alpha-dihydrotestosterone (10(-8)-10(-6) M) did not affect basal lactate accumulation but they enhanced (dose dependent) the response to hFSH: lactate levels after 48 h of treatment with 10(-7) M testosterone plus 100 ng/ml hFSH were 100% higher than those in untreated control cultures. Lactate was refractory to estradiol and progesterone (10(-8)-10(-6) M) even in the presence of hFSH. Progesterone accumulation showed a qualitatively similar pattern of response to the gonadotropins and sex steroids. As expected, the progesterone response to hFSH (100 ng/ml) plus testosterone (10(-7) M) was progressively suppressed in the presence of 10(-7)-10(-5) M nonsteroidal antiandrogen (SCH16423). Lactate accumulation was also reduced. However, maximal inhibition did not exceed 18% in the presence of SCH16423 at 10(-6) or 10(-5) M as compared with the 80% inhibition of progesterone accumulation observed at 10(-5) M. In the absence of androgenic steroid, the lactate response to hFSH was increased approximately 30% by the high dose of SCH16423. A corresponding synandrogenic action of the drug on FSH-sensitive progesterone accumulation was not observed. These results are evidence that carbohydrate metabolism in differentiating granulosa cells is subject to direct and specific control by FSH and androgenic steroid.