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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Steroids can induce both transcription-dependent (genomic) and independent (nongenomic) signaling. Here, several classical androgen receptor ligands were tested for their ability to modulate genomic and nongenomic responses, focusing on the role of the oocyte-expressed Xenopus classical androgen receptor (XeAR) in mediating these processes. Cellular fractionation and immunohistochemistry revealed that the XeAR was located throughout oocytes, including within the plasma membrane. RNA interference and oocyte maturation studies suggested that androgen-induced maturation was mediated in part by the XeAR in a transcription-independent fashion, perhaps by altering G protein-mediated signaling. While inducing minimal transcription in oocytes, all AR ligands promoted significant XeAR-mediated transcription in CV1 cells. In contrast, only testosterone and androstenedione potently induced oocyte maturation, whereas dihydrotestosterone and R1881 actually inhibited testosterone and human chorionic gonadotropin-induced maturation and signaling. These results suggest that the nature of a steroid-induced signal (genomic vs. nongenomic) may depend on the type of target cell, the receptor location within cells, as well as the ligand itself. The identification of molecules capable of selectively altering genomic vs. nongenomic signaling may be useful in delineating the roles of these pathways in mediating androgen responses and might lead to the development of novel compounds that specifically modulate these signals in vivo.
Mol Endocrinol 2003 Jun
PMID:Selective modulation of genomic and nongenomic androgen responses by androgen receptor ligands. 1263 88

Alteration of androgen receptor function due to hormonally active compounds in the environment, may be responsible for impaired reproductive function in aquatic wildlife. Based on human prostate carcinoma 22RV1 cells, a cell culture expression system was established to test effects of putative androgenic/antiandrogenic compounds on endogenous gene expression. 22RV1 cells were shown to express human androgen receptor, but not human progestin (hPR) or human oestrogen receptor (hER) alpha and beta. Six androgen-regulated genes (ARGs) were chosen to determine androgenic/antiandrogenic action using highly sensitive real-time RT-PCR. Results showed that gene expression is altered in a time-dependent manner. After stimulation of cells by DHT (10nM), synthetic androgen R1881 (1 nM), or organic pesticides (difenoconazole, fentinacetate, tetramethrin) TMPRSS2 mRNA expression was down-regulated by the factor 0.6 after 24h of DHT treatment. Similar results were obtained when cells were assayed for mRNA expression of PSA after fentinacetate and R1881 stimulation. In contrast, TMPRSS2 expression was up-regulated by the factor 0.9 when cells were stimulated by tetramethrin. Final goal of the work is a sensitive determination of differential gene expression by different compounds under study, achievement of substance-specific expression patterns and function related analysis of potential androgens/antiandrogens.
J Steroid Biochem Mol Biol 2003 Feb
PMID:Characterisation of gene expression patterns in 22RV1 cells for determination of environmental androgenic/antiandrogenic compounds. 1271 Oct 8

Antioxidants, such as vitamin E, are being investigated for efficacy in prostate cancer prevention. In this study, we show that the antioxidant moiety of vitamin E, 2,2,5,7,8-pentamethyl-6-chromanol (PMCol), has antiandrogen activity in prostate carcinoma cells. In the presence of PMCol, the androgen-stimulated biphasic growth curve of LNCaP human prostate carcinoma cells was shifted to the right. The PMCol-induced growth shift was similar to that produced by treatment with the pure antiandrogen bicalutamide (i.e., Casodex), indicative of androgen receptor (AR) antagonist activity. The concentration of PMCol used was below the concentration required to affect cell growth or viability in the absence of androgen. Using an AR binding competition assay, PMCol was found to be a potent antiandrogen in both LNCaP and LAPC4 cells, with an IC(50) of approximately 10 micro M against 1 nM R1881 (methyltrienolone; a stable, synthetic androgen). Prostate-specific antigen release from LNCaP cells produced by androgen exposure with either 0.05 or 1.0 nM R1881 was inhibited 100% and 80%, respectively, by 30 micro M PMCol. Also, PMCol inhibited androgen-induced promoter activation in both LNCaP and LAPC4 cells. However, PMCol did not affect AR protein levels, suggesting that the inhibitory effects of PMCol on androgenic pathways were not due to decreased expression of the AR. Therefore, growth modulation by the antioxidant moiety of vitamin E in androgen-sensitive prostate carcinoma cells is due, at least in part, to its potent antiandrogenic activity.
Mol Cancer Ther 2003 Aug
PMID:Androgen antagonist activity by the antioxidant moiety of vitamin E, 2,2,5,7,8-pentamethyl-6-chromanol in human prostate carcinoma cells. 1293 70

Steroids are potentially important mediators in the pathophysiology of ocular diseases. In this study, we report on the gene expression in the human eye of a group of enzymes, the 17beta-hydroxysteroid dehydrogenases (17HSDs), involved in the biosynthesis and inactivation of sex steroid hormones. In the eye, the ciliary epithelium, a neuroendocrine secretory epithelium, co-expresses the highest levels of 17HSD2 and 5 mRNAs, and in lesser level 17HSD7 mRNA. The regulation of gene expression of these enzymes was investigated in vitro in cell lines, ODM-C4 and chronic open glaucoma (GCE), used as cell models of the human ciliary epithelium. The estrogen, 17beta-estradiol (10(-7) M) and androgen agonist, R1881 (10(-8) M) elicited in ODM-C4 and GCE cells over a 24 h time course a robust up-regulation of 17HSD7 mRNA expression. 17HSD2 was up-regulated by estradiol in ODM-C4 cells, but not in GCE cells. Under steady-state conditions, ODM-C4 cells exhibited a predominant 17HSD2 oxidative enzymatic activity. In contrast, 17HSD2 activity was low or absent in GCE cells. Our collective data suggest that cultured human ciliary epithelial cells are able to metabolize estrogen, androgen and progesterone, and that 17HSD2 and 7 in these cells are sex steroid hormone-responsive genes and 17HSD7 is responsible to keep on intra/paracrine estrogenic milieu.
J Steroid Biochem Mol Biol 2003 Aug
PMID:Sex steroid hormone metabolism takes place in human ocular cells. 1456 74

Mifepristone is a potent antagonist of steroid hormone receptors such as glucocorticoid and progesterone receptors. We investigated the potential for mifepristone to act as an antiandrogen and compared it with partial androgen receptor (AR) agonists and antagonists, in particular bicalutamide. Mifepristone was an effective antiandrogen in vitro that inhibited transcription from three androgen-responsive promoters and blocked the agonist R1881 in a dose-dependent manner. Like bicalutamide, mifepristone also antagonized the action of androgen receptor with a (T877A) mutation. Mifepristone competed effectively with R1881 with a relative binding affinity comparable to that of cyproterone acetate, and much higher than that of hydroxyflutamide and bicalutamide in a binding assay. Mifepristone could effectively induce the binding of the herpes simplex viral protein 16/AR fusion protein to the hormone response elements in the murine mammary tumor virus-luciferase reporter. With either wild-type or T877A mutant AR, mifepristone alone was unable to induce any detectable interaction with coactivators transcriptional intermediary factor-2 or beta-catenin but could inhibit the R1881-induced binding of AR to transcriptional intermediary factor-2 and beta-catenin. Similarly, mifepristone could inhibit the R1881-induced N/C-terminal interaction in a dose-dependent manner even though mifepristone alone has no effect on the N/C-terminal interaction of AR. We found that mifepristone could induce a strong interaction between AR and corepressors nuclear receptor corepressor and silencing mediator for retinoid and thyroid hormone receptors in both transactivation and two-hybrid assays to a greater degree than hydroxyflutamide, cyproterone acetate, and bicalutamide. The AR-corepressor interaction was also seen in coimmunoprecipitation assays. Finally, mifepristone at high concentrations induced a low level of prostate-specific antigen expression in LNCaP and antagonized prostate-specific antigen expression induced by R1881. Mifepristone also antagonized R1881 action on the growth of LNCaP prostate cancer cells.
Mol Endocrinol 2004 Jan
PMID:Antiandrogen effects of mifepristone on coactivator and corepressor interactions with the androgen receptor. 1459 76

The present work describes the development and optimization of a cell-based androgen reporter assay using the Chinese hamster ovarian cell line (CHO K1) in the 96-well format. The recent reports on increasing exposure of humans and wild-life to environmental endocrine disrupting chemicals (ED) prompt the need for high throughput screening systems for such compounds in environmental and biological samples. To this end, CHO cells were cotransfected with plasmids encoding mouse mammary tumour virus-neomycin-luciferase and human androgen receptor (hAR), and a stable cell line was established. After selection with neomycin, a highly active clone was obtained which stably expressed both the hAR and the androgen-responsive luciferase reporter. Stimulation of the cells with androgens for 24 h resulted in about 15-fold stimulation of luciferase activity, with the minimum effective dose of testosterone being 0.1 nmol/l. Potent steroidal and non-steroidal anti-androgens, such as hydroxyflutamide and cyproterone acetate, significantly inhibited the androgen-induced transactivation. Non-androgenic steroids like estradiol, progesterone, dexamethasone and cortisol showed weak activity at high concentrations. RT-PCR and western blot confirmed proper transcription and translation as well as stable expression of the AR gene in the cells. About 60 different chemicals (mostly pesticides or their metabolites, and common industrial chemicals) were screened with the cell line for their ability to stimulate luciferase activity or inhibit that evoked by 0.1 nmol/l R1881, used as a positive androgenic control. About 10 highly potent anti-androgenic chemicals were identified. The most potent anti-androgenic compounds identified in our assay included bisphenol A, alpha-hexachlorocyclohexane, vinclozolin and 4,4-DDE. These compounds had alone either no effect or were weak agonists (with cytotoxic effects at very high concentrations), but none showed any significant agonistic activity. In conclusion, we demonstrate that the bioassay based on this cell line provides a reliable test for detecting androgenic and anti-androgenic compounds. The 96-well plate format makes the assay suitable for high throughput screening.
J Steroid Biochem Mol Biol 2004 Feb
PMID:Screening of some anti-androgenic endocrine disruptors using a recombinant cell-based in vitro bioassay. 1508 47

Androgen insensitivity syndrome (AIS) is an X-linked disease caused by mutations in the androgen receptor (AR) resulting in various degrees of defective masculinization in 46,XY individuals. In the present study, we describe a novel mutation in exon 7 of the AR gene in an Egyptian patient with partial AIS (PAIS). Sequencing analysis of the AR gene revealed a novel missense mutation, P817A, within the ligand-binding domain (LBD). This is the first report of a mutation within the short amino acid motif (codons 815-817) of the beta-strand lying between helices H8 and H9 of the AR LBD. The functional defects of the mutated protein were characterized by in vitro study and included significantly decreased ligand-binding affinity and impaired transactivation potential. Limited proteolysis assays performed with the wild-type and mutant AR receptors incubated with the synthetic agonist R1881 revealed that the P817A mutation resulted in a reduced stabilization of the AR active conformation. Structural analyses showed that this mutation is likely to perturb the beta-sheet interaction between residues 815-817 and 911-913. This structural alteration destabilizes the position of the C-terminal extension, which contains residues critical for androgen function.
J Mol Endocrinol 2004 Jun
PMID:A new mutation of the androgen receptor, P817A, causing partial androgen insensitivity syndrome: in vitro and structural analysis. 1517 8

Androgens play important endocrine roles in development and physiology. Here, we characterize activities of two "Andro" prohormones, androstenedione (A-dione) and 4-androsten-3beta,17beta-diol (A-diol) in MDA-MB-453 (MDA) and LNCaP cells. A-dione and A-diol, like cyproterone acetate, were partial agonists of transfected mouse mammary tumor virus (MMTV) and endogenous prostate-specific antigen (PSA) promoters. Different from bicalutamide but similar to CPA, both are inducers of LNCaP cell proliferation with only mild suppression of 5alpha-dihydrotestosterone (DHT)-enhanced cell growth. Like bicalutamide and cyproterone acetate, A-dione and A-diol significantly antagonized DHT/R1881-induced PSA expression by up to 30% in LNCaP cells. Meanwhile, in MDA cells, EC(50)s for the MMTV promoter were between 10 and 100nM. Co-factor studies showed GRIP1 as most active for endogenous androgen receptor (AR), increasing MMTV transcription by up to five-fold, without substantially altering EC(50)s of DHT, A-dione or A-diol. Consistent with their transcriptional activities, A-dione and A-diol bound full-length endogenous AR from MDA or LNCaP cells with affinities of 30-70nM, although binding to expressed ligand-binding domain (LBD) was >20-fold weaker. In contrast, DHT, R1881, and bicalutamide bound similarly to LBD or aporeceptor. Together, these data suggest that A-dione and A-diol are ligands for AR with partial agonist/antagonist activities in cell-based transcription assays. Binding affinities for both are most accurately assessed by AR aporeceptor complex. In addition to being testosterone precursors in vivo, either may impart its own transcriptional regulation of AR.
J Steroid Biochem Mol Biol 2004 Aug
PMID:Partial agonist/antagonist properties of androstenedione and 4-androsten-3beta,17beta-diol. 1533 2

We characterized the specifically androgen-regulated gene (SARG), which is expressed in the androgen receptor (AR) and glucocorticoid receptor (GR) positive cell line lymph node carcinoma of the prostate-1F5 (LNCaP-1F5). SARG mRNA expression can be up-regulated by androgens, but not by glucocorticoids. SARG mRNA expression is high in prostate tissue. SARG is composed of four exons and spans a region of 14.5 kbp on chromosome 1q32.2. Transcripts of 5.5, 3.3 and 2.3 kb are the result of alternative polyadenylation. SARG mRNA splice variants lack exon 2 and vary in length of exon 1. The SARG protein has a length of 601 amino acids and is located in the cytoplasm. By screening the 18 kbp genomic sequence flanking the transcription start site we identified the imperfect direct repeat 5'-TGTGCTaacTGTTCT-3'in intron 1 as an active androgen response element (ARE-SARG+4.6). A 569 bp genomic DNA fragment containing this element functioned as an androgen-specific enhancer in transiently transfected LNCaP-1F5 cells. ARE-SARG+4.6 cooperated with flanking sequences for optimal activity. Inactivation of ARE-SARG+4.6 completely abolished the androgen response of the enhancer. Chromatin immunoprecipitation (ChIP) experiments showed chromatin structural changes of the enhancer in the presence of R1881. ARE-SARG+4.6 was able to bind to the androgen receptor, but not to the glucocorticoid receptor, correlating with its androgen-specific activity in transfections.
J Mol Endocrinol 2004 Oct
PMID:A bioinformatics-based functional analysis shows that the specifically androgen-regulated gene SARG contains an active direct repeat androgen response element in the first intron. 1552 3

The involvement of mutated androgen receptors (mut-AR) in the actions of estrogens in prostate cancer cells is controversial. This work was designed to determine the role of such receptors in the growth inhibition by estradiol (E2) and androgens of the MOP cell line, a derivative of the LNCaP cell line. Diethylstilbestrol (DES) was used as a "tool". E2 like DHT and R1881 inhibits MOP cell proliferation while DES does not. E2 and R1881 down regulate mut-AR mRNA, DES does not. E2 enhances mut-AR transcriptional activity less efficiently than R1881 while DES does not. E2 and R1881 up regulate PSA secretion in a dose-dependent manner, DES does it marginally at 10(-6)M. MOP cells express low amounts of ERalpha and ERbeta mRNA but neither DES nor E2 and R1881 do enhance ER transcriptional activity. DES and E2 bind to mut-AR with relative binding affinities which are respectively 1/175 and 1/10 that of DHT. The E2 and androgen-repressed proliferation is prevented by DES and by the anti-androgen bicalutamide. In LNCaP cells, DES prevents the androgen-enhanced proliferation. These results strongly suggest that: (a) the putative endogenous ERs are biologically inactive in MOP cells, (b) the E2-repressed proliferation results from hormone binding to mut-AR and, (c) DES is an anti-androgen in mut-AR expressing cell line.
J Steroid Biochem Mol Biol 2005 Jul
PMID:Divergent biological effects of estradiol and diethylstilbestrol in the prostate cancer cell line MOP. 1595 Apr 59


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