Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the presence of sodium molybdate and protease inhibitors, two forms of androgen-receptor complexes were observed which sedimented in the areas of 8-9S and 5-7S by SDG centrifugation. The intermediary 5-7S form was better seen when complexes were incubated at low KCl concentrations. The sedimentation coefficient of this form fluctuated between 5 and 7S depending on the KCl concentration. At high ionic strength (0.6M KCl) in all media, one form only was observed having a sedimentation coefficient value of 4.3S. By gel exclusion chromatography, we also observed two specific entities at 75A and 68A; in the presence of 0.6M KCl, however, two entities were found at 68A and 43A. The constant presence of protease inhibitors in all buffers was necessary to separate the intermediary 68A form. We calculated molecular weights of about 270 kDa, 190 kDa, and 80 kDa respectively for these three forms. [3H]R1881-receptor complexes bound to DEAE-cellulose and were eluted in the absence of glycerol at 0.1M and 0.2M KCl. Material found at 0.1M KCl sedimented in the areas of 5-7S and 8-9S in nearly equal proportion, and that found at 0.2M KCl sedimented in the 8-9S area only. When the cytosol was chromatographed at a fast flow rate (4 ml/min), untransformed 8-9S receptors did not bind to phosphocellulose, but transformed complexes were retained, could be eluted with 0.4M KCl and sedimented in the 4S area on KCl free SDG centrifugation. When the excluded untransformed 8-9S complexes were re-chromatographed at a slow flow rate (1 ml/min), they were retained on phosphocellulose, and could be eluted with 0.3M KCl.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1989 Oct 05
PMID:Studies on the characterization of rat prostate androgen receptors. 260 33

The androgen receptor in human prostate carcinoma cells (LNCaP) has been studied after in situ photolabeling with [3H]R1881. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of whole cell extracts revealed the presence of two specifically labeled proteins of 110 kDa and 43 kDa. Both photolabeled proteins were stable in cell homogenates and generated different chymotryptic maps, suggesting that the two proteins were different. From ligand binding specificity studies could be concluded that the 110 kDa protein represents the androgen receptor. The 43 kDa protein showed binding specificity only for R1881. Both photolabeled proteins were recovered from LNCaP nuclei, but the 43 kDa protein showed a relatively higher affinity for nuclei than the 110 kDa protein. The function of this protein is unknown. It is concluded that the human androgen receptor is a protein with a molecular mass of 110 kDa.
Mol Cell Endocrinol 1989 May
PMID:The human androgen receptor is a 110 kDa protein. 278 63

Using methods for cell lysis and fractionation which yield essentially quantitative recovery of rat prostate cancer cell cytosolic and nuclear androgen receptors, we examined androgen modulation of androgen receptor content of clonally derived prostate cancer cell lines. We showed that testosterone elicited a concentration-dependent 2.3-fold increase in T5 cell androgen receptor content which was maximum after 48 h and was maintained through at least 72 h of culture. Testosterone caused only a 1.4-fold elevation in D2 cell androgen receptor content which was maximum between 6 and 12 h of culture and was maintained through at least 72 h culture. In contrast, testosterone did not cause a change in C3 cell androgen receptor content. Cycloheximide inhibition showed that both the testosterone-mediated increase in and maintenance of basal prostate cancer cell androgen receptor content required protein synthesis. Because testosterone and the nonmetabolizable androgen R1881 were essentially equipotent as effectors of the increase in T5 cell androgen receptor content, findings using testosterone appear to represent maximum effects. RU 23908 antagonized both R1881 and testosterone promoted elevations of prostate cancer cell androgen receptor content. Effectiveness of RU 23908 was comparable to the relative binding affinity of R1881, testosterone and RU 23908 for androgen receptors. This implies that at least part of the androgen-promoted increase in prostate cancer cell androgen receptor content is mediated through the action of androgen receptors and suggests that androgen receptors may act as both cis and trans regulatory elements. The mechanisms which determine basal or androgen-modulated prostate cancer cell androgen receptor content remain to be elucidated.
Mol Cell Endocrinol 1989 May
PMID:Androgen modulation of prostate cancer cell androgen receptor content is cell line specific. 278 64

Prolonged exposure of genital skin fibroblasts (GSF) to dihydrotestosterone (DHT) increases androgen receptor binding of steroid, a process termed 'up-regulation'. Because the extent of up-regulation appears to be quite variable, we have investigated the optimal conditions and the molecular mechanisms that control this phenomenon in seven strains of normal neonatal GSF. When GSF were incubated for 1-48 h with 3 nM methyltrienolone (R1881), maximal up-regulation was reached by 20 h and remained constant thereafter. With DHT, rapid steroid metabolism required replenishment of DHT for maximum up-regulation. Up-regulation levels following 20 h incubation with DHT (including steroid replenishment) and R1881 were 2.07-fold (range = 1.1-3.3) and 2.35-fold (range = 1.86-3.33), respectively. The greater variability observed with DHT may be related to variable rates of steroid catabolism among cell strains. Half-maximal up-regulation was attained at 0.29 nM R1881, which approximates the Kd. Maximal up-regulation was reached only with continuous exposure to R1881 for 24 h. It was completely inhibited by actinomycin D (0.5 micrograms/ml) or cycloheximide (10 micrograms/ml). Following up-regulation, removal of R1881 for 24 h resulted in a highly variable decline of androgen receptors among cell strains. Maximal up-regulation could be reinduced by exposure to R1881 again for an additional 24 h. During up-regulation, androgen receptor levels in nuclei and nuclear matrix rose with increments comparable to those obtained in whole cells. We conclude that the extent of up-regulation and its rate of decline differ greatly among normal cell strains. Hence, its study in cells of patients with androgen insensitivity may have limited value.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1988 Jun
PMID:Studies of up-regulation of androgen receptors in genital skin fibroblasts. 326 Dec 67

The translocation of the androgen receptor in prostatic tissue has been studied under the influence of different ligands (testosterone, methyltrienolone and cyproterone acetate) in vivo and in vitro. Nuclear and cytoplasmic androgen receptors were estimated using an exchange assay with [3H]methyltrienolone ( [3H]R1881) 1 h and 16 h after injection in castrated rats of either 100 micrograms testosterone (T), 10 mg cyproterone acetate (CA) or the combination of T and CA. Within 1 h after T administration, nuclear receptor levels increased with a concomitant depletion of cytosol receptors. In the CA-treated rats nuclear receptor levels were not different from those of control castrated animals and there was no depletion of cytosol receptors. The combined treatment of T and CA resulted in a partial depletion of cytosol receptors and a simultaneous increase of nuclear receptors. The absence of an increase in nuclear androgen receptors in CA-treated animals cannot be explained by a delay in translocation, because even 16 h after CA injection, only a very small number of nuclear receptors were detectable. Incubation of minced prostatic tissue with [3H]CA or [3H]R 1881 resulted in receptor translocation only in the R1881 incubations and confirmed the in vivo results. Competition studies with different steroids and cytosol receptor (non-activated, 8S form in low salt gradient) or nuclear receptor (activated 3.6S form in high salt gradient) of prostatic tissue show that CA can compete with R1881 for specific androgen-binding sites with a similar relative binding affinity for both receptor preparations. The present results provide evidence that CA prevents translocation of the androgen receptor to the nucleus, although CA can be bound with similar affinities to the nuclear receptor and the cytoplasmic receptor. We propose that the anti-androgenic action of CA involves an inhibition of receptor translocation.
Mol Cell Endocrinol 1983 Oct
PMID:Cyproterone acetate prevents translocation of the androgen receptor in the rat prostate. 622 11

We have recently demonstrated that the biphasic action of androgens on LNCaP cell proliferation is opposite to their effect on apolipoprotein D (apo-D) secretion, the stimulation of apo-D secretion being associated with a steroid-induced inhibition of cell proliferation. To further characterize the control of apo-D expression in LNCaP cells, we studied basal as well as androgen-induced apo-D secretion in slowly proliferating, low-passage (LP; 20-29th) and rapidly proliferating high-passage (HP; 111-117th) cell cultures. For comparison, the androgen-induced stimulation of prostate specific antigen secretion was also investigated in LP and HP cell cultures. In the absence of androgens, basal cell proliferation of HP cells was significantly higher than that of LP cells, whereas apo-D secretion was higher in LP cells than in HP cells. Furthermore, the biphasic action of dihydrotestosterone and of the synthetic androgenic compound R1881 on apo-D release and cell proliferation was observed in both LP and HP cells. The stimulation of apo-D secretion was inversely related to that of cell proliferation and influenced by cell density. The inhibition of basal and androgen-induced cell proliferation by the calcium channel blocker nifedipine was also associated with an increase in apo-D secretion. The amount of PSA released and the sensitivity of its response to R1881 were increased in LP cells compared with HP cells. The present study thus demonstrates, for the first time, that apo-D secretion is inversely correlated to cell proliferation and cell density in the absence as well as in the presence of androgens in both LP and HP LNCaP human prostate cancer cells. This finding suggests that apo-D expression can be modulated not only by steroid hormones, but also by other factors involved in the control of cell proliferation.
J Steroid Biochem Mol Biol 1994 Nov
PMID:Inverse relationships between cell proliferation and basal or androgen-stimulated apolipoprotein D secretion in LNCaP human prostate cancer cells. 752 88

To study the mechanisms by which androgens intervene in the regulation of growth and differentiation of human prostatic epithelial cells, cDNA clones encoding putative prostate-secreted proteins were characterized and tested as potential markers for androgen action. One of the isolated cDNAs expressed diazepam-binding inhibitor/acyl-CoA-binding protein (DBI/ACBP), suggesting that this polypeptide, that has been implicated in a large number of biochemical processes, is expressed and secreted by prostate cells. As demonstrated by Northern blot analysis, the mRNA encoding DBI/ACBP was expressed in prostate tissue and in the three human prostatic adenocarcinoma cell lines tested: LNCaP, PC-3 and DU-145. In androgen-sensitive LNCaP cells, the synthetic androgen R1881 stimulated the DBI/ACBP steady state mRNA levels with half maximal effects at a concentration of 0.2 nM. Increases were a maximal 12 h after addition of the synthetic hormone. DBI/ACBP mRNA levels could also be stimulated by the synthetic androgen mibolerone and by the natural androgens testosterone and dihydrotestosterone. In agreement with the altered steroid specificity of the androgen receptor in LNCaP cells, estradiol and progesterone also exerted a stimulatory effect. Cortisol and the synthetic glucocorticoid dexamethasone were without effect. Androgen stimulation of DBI/ACBP mRNA levels was abolished in the presence of the protein synthesis inhibitor cycloheximide, implying a role for labile or androgen-induced proteins in this androgen stimulation. This is in contrast to the androgen stimulation of the mRNA encoding prostate-specific antigen (PSA), suggesting that different mechanisms are involved in the androgen regulation of these two genes. Although further experiments are required to confirm that DBI/ACBP is secreted by prostatic epithelial cells, these data demonstrate that the mRNA encoding DBI/ACBP is expressed in prostate cells and is affected by androgens in androgen-responsive LNCaP cells.
Mol Cell Endocrinol 1994 Sep
PMID:Androgen regulation of the messenger RNA encoding diazepam-binding inhibitor/acyl-CoA-binding protein in the human prostatic adenocarcinoma cell line LNCaP. 752 52

There is increasing evidence that the course of prostatic carcinoma is determined by a complex interplay between genetic events, paracrine interactions, and hormonal and dietary factors. These latter factors include several ligands of the nuclear receptor family such as androgens, vitamin D3 and retinoids. To test whether thyroid hormones also influence the growth and differentiated function of prostatic carcinoma cells, LNCaP cells were treated with or without triiodothyronine (T3) in the absence or in the presence of other regulatory factors. Exposure of LNCaP cells to T3 for 6 days in the absence of androgens caused a dose-dependent increase in [3H]-thymidine incorporation with a maximal stimulation of 2.5-fold at 10(-9) M T3. Secretion of prostate-specific antigen (PSA) was also stimulated 2-3-fold. The observed effects may well be mediated by a nuclear T3 receptor as evidenced by displaceable T3 binding studies. Combined treatment of LNCaP cells with androgens and T3 revealed intriguing interactions between these two pathways. Below and up to 10(-10) M of the synthetic androgen R1881, the concentration that evokes optimal proliferative responses, T3 stimulated [3H] thymidine incorporation. At higher concentrations of androgens, T3 displayed antiproliferative effects. No androgen-dependent effects on T3 receptor levels were observed. Conversely, T3 increased androgen receptor levels up to twofold. Androgen as well as T3 stimulation of proliferation was abolished by high concentrations of the retinoid 9-cis-retinoic acid. These data add T3 to the list of factors that influence growth and differentiation of prostatic tumor cells and contribute to our understanding of the intricate pathways that ultimately determine the course of prostatic carcinoma.
Mol Cell Endocrinol 1995 Mar
PMID:Triiodothyronine modulates growth, secretory function and androgen receptor concentration in the prostatic carcinoma cell line LNCaP. 754 May 69

Androgen (R1881) induced transcriptional activity of the human androgen receptor, stably expressed in CHO cells, can be stimulated an extra 2-fold by the addition of the protein kinase C activator, 4 beta-phorbol 12-myristate 13-acetate (PMA). This extra stimulation is not observed when the protein kinase A activator bromoadenosine 3':5'-cyclic monophosphate (8-BrcAMP) is used. The transcriptional activity was measured using a reporter plasmid containing the MMTV-promoter, coupled to the luciferase gene. The effect of PMA on R1881-induced transcription was not due to a higher expression level of the androgen receptor. Also, no extra phosphorylation of the androgen receptor could be measured after incubation with PMA. When GRE-tk-LUC and PSA-LUC reporters were used, the synergistic effect of PMA could not be observed. The findings on the composite MMTV-LTR promoter can be explained by either a direct synergistic interaction between occupied AP-1 like responsive elements and the androgen receptor or via an unknown transcription factor activated by the PKC pathway and interacting with the androgen receptor.
Mol Cell Endocrinol 1995 Apr 28
PMID:Synergism between androgens and protein kinase-C on androgen-regulated gene expression. 767 38

The molecular basis for the different physiological effects of testosterone (T) and dihydrotestosterone (DHT) was investigated using recombinantly expressed wild-type and mutant androgen receptor (AR). Rates of androgen dissociation from nuclear and cytoplasmic AR were compared with hormone- and concentration-dependent receptor degradation rates. T dissociates from AR 3 times faster than DHT or methyltrienolone (R1881) and is less effective in stabilizing the receptor. Analysis of AR deletion mutants and AR/glucocorticoid receptor chimeras indicates that the AR NH2-terminal domain has a specific role in stabilizing the receptor by slowing the rate of ligand dissociation and AR degradation. Amino acid mutations that abolish receptor dimerization, nuclear localization, or DNA-binding activity have no significant effect on androgen dissociation or AR degradation. A naturally occurring steroid-binding domain mutation (Val889 to Met) that causes androgen insensitivity, but does not alter equilibrium androgen binding affinity, lowered the androgen-binding capacity as a result of increased rates of androgen dissociation and AR degradation. Thus, AR stabilization and function require prolonged receptor occupancy with androgen, with a similar extent of stabilization observed at higher concentrations of faster dissociating androgens and lower concentrations of slower dissociating androgens. Retention of receptor-bound androgen is enhanced by an interaction between the AR NH2-terminal and steroid-binding domains. The ligand specificity and concentration dependence of receptor stabilization provide an explanation for physiological differences in the actions of T and DHT.
Mol Endocrinol 1995 Feb
PMID:Specificity of ligand-dependent androgen receptor stabilization: receptor domain interactions influence ligand dissociation and receptor stability. 777 71


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>