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Eppo Mulder - One of the best experts on this subject based on the ideXlab platform.
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Studies on the Human Prostatic Cell Line LNCaP Cancer
1994Co-Authors: Jos Veldscholte, Cor A Berrevoets, Eppo MulderAbstract:The effects of androgens, antiandrogens, and other steroid hormones on growth of the human prostate cancer cell line LNCaP were studied. Despite the absence of receptors for progesterone and estradiol, the growth rate of the androgen responsive LNCaP-FGC cells increased when cultured in the presence of either estrogens or progestagens. In addition, most antiandrogens were also growth stimulators. This aberrant response was due to a threonine to alanine substitution at amino acid position 868 in the steroid binding domain of the androgen receptor (AR). Only the antiandrogen ICI 176 334 could block transcription and cell growth by the mutant receptor. By immunoprecipitation of the AR from LNCaP cells with the specific antibody F39.4.1 and Western blotting, three types of heat-shock proteins co-precipitated: hsp90, hsp70 and hsp56. This co-isolation could be prevented by pre-incubating the cells with androgens or with the antiandrogen Hydroxyflutamide . Only the antiandrogen ICI 176 334 could block the effect of androgens on complex dissociation and prevent tight nuclear binding of the AR. Hydroxyflutamide could only inhibit tight nuclear binding of the wild-type AR. Therefore, in LNCaP cells the mutation in the steroid binding domain of the AR prevents a blockade of receptor function by most antiandrogens, but not by ICI 176 334, probably because of a different mechanism by which this compound blocks receptor function.
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Studies on the human prostatic cancer cell line LNCaP.
The Journal of steroid biochemistry and molecular biology, 1994Co-Authors: Jos Veldscholte, Cor A Berrevoets, Eppo MulderAbstract:The effects of androgens, antiandrogens, and other steroid hormones on growth of the human prostate cancer cell line LNCaP were studied. Despite the absence of receptors for progesterone and estradiol, the growth rate of the androgen responsive LNCaP-FGC cells increased when cultured in the presence of either estrogens or progestagens. In addition, most antiandrogens were also growth stimulators. This aberrant response was due to a threonine to alanine substitution at amino acid position 868 in the steroid binding domain of the androgen receptor (AR). Only the antiandrogen ICI 176,334 could block transcription and cell growth by the mutant receptor. By immunoprecipitation of the AR from LNCaP cells with the specific antibody F39.4.1 and Western blotting, three types of heat-shock proteins co-precipitated: hsp90, hsp70 and hsp56. This co-isolation could be prevented by pre-incubating the cells with androgens or with the antiandrogen Hydroxyflutamide. Only the antiandrogen ICI 176,334 could block the effect of androgens on complex dissociation and prevent tight nuclear binding of the AR. Hydroxyflutamide could only inhibit tight nuclear binding of the wild-type AR. Therefore, in LNCaP cells the mutation in the steroid binding domain of the AR prevents a blockade of receptor function by most antiandrogens, but not by ICI 176,334, probably because of a different mechanism by which this compound blocks receptor function.
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EFFECTS OF ANTIANDROGENS ON TRANSFORMATION AND TRANSCRIPTION ACTIVATION OF WILD-TYPE AND MUTATED (LNCaP) ANDROGEN RECEPTORS
The Journal of steroid biochemistry and molecular biology, 1993Co-Authors: Cor A Berrevoets, Jos Veldscholte, Eppo MulderAbstract: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.
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Anti-androgens and the mutated androgen receptor of LNCaP cells: differential effects on binding affinity, heat-shock protein interaction, and transcription activation.
Biochemistry, 1992Co-Authors: Jos Veldscholte, Cor A Berrevoets, Albert O. Brinkmann, J. Anton Grootegoed, Eppo MulderAbstract:Previous studies from this laboratory have described that LNCaP prostate tumor cells contain an androgen receptor (AR) with a point mutation in the steroid-binding domain (codon 868, Thr to Ala). This defect leads to a change in specificity of the AR. Estrogens, progestagens, and some anti-androgens (e.g., cyproterone acetate, Hydroxyflutamide, nilutamide) stimulate LNCaP cell growth rate through the AR. The present studies indicate that not all anti-androgens showed agonistic effects with the mutated receptor. The growth rate of LNCaP cells did not increase with the anti-androgen ICI 176334, nor could this compound increase transcription activation of the reporter gene construct via the mutant receptor in a cotransfection system [HeLa cell cotransfection system with an androgen-regulated reporter gene construct (pG29G-tk-CAT) and the mutant receptor as trans-vector]. Interaction of the AR of LNCaP cells with heat-shock proteins was studied by isolation of the receptor with a specific monoclonal antibody and characterization of associated proteins. Hsp90, hsp70, and hsp56 were found to coprecipitate with the AR. Incubation of the cells at 37 degrees C with androgen (R1881, 10 nM) or the anti-androgen Hydroxyflutamide, prior to receptor isolation, resulted in dissociation of the AR-heat-shock protein complex. This dissociation is paralleled by the transformation to a tight nuclear-binding form of the AR. In contrast, ICI 176334 could not induce a release of heat-shock proteins and did not increase nuclear binding, but inhibited the transformation process induced by R1881.(ABSTRACT TRUNCATED AT 250 WORDS)
Chawnshang Chang - One of the best experts on this subject based on the ideXlab platform.
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3β acetoxyandrost 1 5 diene 17 ethylene ketal functions as a potent antiandrogen with marginal agonist activity
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Hiroshi Miyamoto, Padma Marwah, Ashok Marwah, Henry A Lardy, Chawnshang ChangAbstract:The majority of available antiandrogens have been reported to possess agonist activity to induce prostate-specific antigen, which might result in antiandrogen withdrawal syndrome. Here we report the identification of 3β-acetoxyandrost-1,5-diene-17-ethylene ketal (ADEK) from dehydroepiandrosterone metabolites and derivatives as a potent antiandrogen. We found ADEK could interrupt androgen binding to the androgen receptor (AR) and suppress androgen-induced transactivations of WT AR and a mutant AR in prostate cancer cells. ADEK inhibited prostate-specific antigen expression as well as growth in LNCaP prostate cancer cells stimulated by androgen. Importantly, ADEK had only marginal agonist effects, as compared with commonly used antiandrogens such as Hydroxyflutamide and bicalutamide, leading to a lower possibility of inducing withdrawal response. Moreover, ADEK could block an adrenal androgen androstenediol-induced AR transactivation that Hydroxyflutamide and bicalutamide failed to block. These unique antiandrogenic activities make ADEK a potential therapeutic compound that might be able to inhibit AR-mediated prostate cancer progression. Further in vivo studies might facilitate the development of a better antiandrogen for the treatment of prostate cancer.
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Suppression of Δ5-androstenediol-induced androgen receptor transactivation by selective steroids in human prostate cancer cells
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Hong-chiang Chang, Hiroshi Miyamoto, Padma Marwah, Henry A Lardy, Shuyuan Yeh, Ko En Huang, Chawnshang ChangAbstract:Our earlier report suggested that androst-5-ene-3β,7β-diol (Δ5-androstenediol or Adiol) is a natural hormone with androgenic activity and that two potent antiandrogens, Hydroxyflutamide (Eulexin) and bicalutamide (Casodex), fail to block completely the Adiol-induced androgen receptor (AR) transactivation in prostate cancer cells. Here, we report the development of a reporter assay to screen several selective steroids with anti-Adiol activity. Among 22 derivatives/metabolites of dehydroepiandrosterone, we found 4 steroids [no. 4, 1,3,5(10)-estratriene-17α-ethynyl-3,17β-diol; no. 6, 17α-ethynyl-androstene-diol; no. 8, 3β,17β-dihydroxy-androst-5-ene-16-one; and no. 10, 3β-methylcarbonate-androst-5-ene-7,17-dione] that have no androgenic activity and could also block the Adiol-induced AR transactivation in prostate cancer PC-3 cells. Interestingly, these compounds, in combination with Hydroxyflutamide, further suppressed the Adiol-induced AR transactivation. Reporter assays further showed that these four anti-Adiol steroids have relatively lower glucocorticoid, progesterone, and estrogenic activity. Together, these data suggest some selective steroids might have anti-Adiol activity, which may have potential clinical application in the battle against the androgen-dependent prostate cancer growth.
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Evaluation of RU58841 as an anti-androgen in prostate PC3 cells and a topical anti-alopecia agent in the bald scalp of stumptailed macaques
Endocrine, 1998Co-Authors: Huei-ju Pan, George Wilding, Hideo Uno, Shigeki Inui, Lowell Goldsmith, Edward Messing, Chawnshang ChangAbstract:The effect of androgen receptor transcriptional activation by RU58841, a nonsteroidal anti-androgen, was studied in the human prostate cancer PC3 cell line by cotransfection with wild-type androgen receptor (wt AR) and an androgen-responsive reporter (MMTV-ARE-CAT) construct. Anti-androgens, Hydroxyflutamide, and Casodex, and the antiestrogen, genistein, were studied in parallel for comparison with RU58841. The wt AR was activated only by the androgen dihydrotestosterone (DHT). Neither the anti-androgens nor antiestrogen can enhance AR transcriptional activity at 10^−11-10^−7 M in PC3 cells. Hydroxyflutamide, RU58841, and Casodex, but not genistein, displayed competitively suppressive effects on DHT activation of wt AR. The potency of RU58841 was comparable to that of Hydroxyflutamide. From this result, topical application of RU58841, which is considered to be a potential therapy for skin diseases, may induce systemic side effects. However, RU58841, on topical application, revealed a potent increase in density, thickening, and length of hair in the macaque model of androgenetic alopecia, whereas no systemic effects were detected. Together our results suggest that RU58841 may have potent antagonism to the wt AR and could be considered as a topically applied active anti-androgen for the treatment of androgen-dependent skin disorders, such as acne, androgenetic alopecia, and hirsutism.
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Hydroxyflutamide may not always be a pure antiandrogen.
Lancet (London England), 1997Co-Authors: Shuyuan Yeh, Hiroshi Miyamoto, Chawnshang ChangAbstract:A and B: 1·5 μg wild-type hAR alone (columns 1, 2, 3, and 4) and cotransfected with 4·5 μg ARA70 (5, 6, 7, and 8) in the absence or presence of 10, 10, 10 mol/L of Hydroxyflutamide. C the mutant AR877 was used to replace the wild-type AR to perform the same experiment on panel B. All experiments were performed in human prostate cancer DU145 cells cultured in DMEM with 5% charcoalstripped fetal calf serum. In each transfection, 3·5 μg of PSA-ARE CAT (A) or MMTV-ARE CAT (B and C) were used as a reporter. The mock treatment of lane 1 was counted as standard one-fold. Relative CAT activity was calculated by the quantitation of phosphorimager. Data represent an average of at least three experiments. THE LANCET
Hiroshi Miyamoto - One of the best experts on this subject based on the ideXlab platform.
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Androgen Receptor Signaling Reduces Radiosensitivity in Bladder Cancer.
Molecular cancer therapeutics, 2018Co-Authors: Hiroki Ide, Satoshi Inoue, Taichi Mizushima, Guiyang Jiang, Kuang-hsiang Chuang, Mototsugu Oya, Hiroshi MiyamotoAbstract:Although radiotherapy often with chemotherapy has been shown to offer a survival benefit comparable to that of radical cystectomy in select patients with bladder cancer, the development of radiosensitization strategies may significantly enhance its application. Notably, emerging preclinical evidence has indicated the involvement of androgen receptor (AR) signaling in urothelial cancer progression. We here assessed whether AR signals could contribute to modulating radiosensitivity in bladder cancer cells. Ionizing radiation reduced the numbers of viable cells or colonies of AR-negative lines more significantly than those of AR-positive lines. Similarly, in AR-positive cells cultured in androgen-depleted conditions, dihydrotestosterone treatment lowered the effects of irradiation. Meanwhile, an anti-androgen Hydroxyflutamide enhanced them in AR-positive cells cultured in the presence of androgens. AR knockdown or Hydroxyflutamide treatment also resulted in a delay in DNA double-strand break repair 4-24 hours after irradiation. We then established "radiation-resistant" sublines and found considerable elevation of the expression of AR as well as DNA repair genes, such as ATR, CHEK1, and PARP-1, in these sublines, compared with respective controls. Furthermore, dihydrotestosterone induced the expression of these DNA repair genes in irradiated AR-positive cells, and Hydroxyflutamide antagonized the androgen effects. Finally, in a mouse xenograft model, low-dose flutamide was found to enhance the inhibitory effects of irradiation, and its tumor size was similar to that of AR knockdown line with radiation alone. These findings suggest that AR activity inversely correlates with radiosensitivity in bladder cancer. Accordingly, anti-androgenic drugs may function as sensitizers of irradiation, especially in patients with AR-positive urothelial cancer.
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3β acetoxyandrost 1 5 diene 17 ethylene ketal functions as a potent antiandrogen with marginal agonist activity
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Hiroshi Miyamoto, Padma Marwah, Ashok Marwah, Henry A Lardy, Chawnshang ChangAbstract:The majority of available antiandrogens have been reported to possess agonist activity to induce prostate-specific antigen, which might result in antiandrogen withdrawal syndrome. Here we report the identification of 3β-acetoxyandrost-1,5-diene-17-ethylene ketal (ADEK) from dehydroepiandrosterone metabolites and derivatives as a potent antiandrogen. We found ADEK could interrupt androgen binding to the androgen receptor (AR) and suppress androgen-induced transactivations of WT AR and a mutant AR in prostate cancer cells. ADEK inhibited prostate-specific antigen expression as well as growth in LNCaP prostate cancer cells stimulated by androgen. Importantly, ADEK had only marginal agonist effects, as compared with commonly used antiandrogens such as Hydroxyflutamide and bicalutamide, leading to a lower possibility of inducing withdrawal response. Moreover, ADEK could block an adrenal androgen androstenediol-induced AR transactivation that Hydroxyflutamide and bicalutamide failed to block. These unique antiandrogenic activities make ADEK a potential therapeutic compound that might be able to inhibit AR-mediated prostate cancer progression. Further in vivo studies might facilitate the development of a better antiandrogen for the treatment of prostate cancer.
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Suppression of Δ5-androstenediol-induced androgen receptor transactivation by selective steroids in human prostate cancer cells
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Hong-chiang Chang, Hiroshi Miyamoto, Padma Marwah, Henry A Lardy, Shuyuan Yeh, Ko En Huang, Chawnshang ChangAbstract:Our earlier report suggested that androst-5-ene-3β,7β-diol (Δ5-androstenediol or Adiol) is a natural hormone with androgenic activity and that two potent antiandrogens, Hydroxyflutamide (Eulexin) and bicalutamide (Casodex), fail to block completely the Adiol-induced androgen receptor (AR) transactivation in prostate cancer cells. Here, we report the development of a reporter assay to screen several selective steroids with anti-Adiol activity. Among 22 derivatives/metabolites of dehydroepiandrosterone, we found 4 steroids [no. 4, 1,3,5(10)-estratriene-17α-ethynyl-3,17β-diol; no. 6, 17α-ethynyl-androstene-diol; no. 8, 3β,17β-dihydroxy-androst-5-ene-16-one; and no. 10, 3β-methylcarbonate-androst-5-ene-7,17-dione] that have no androgenic activity and could also block the Adiol-induced AR transactivation in prostate cancer PC-3 cells. Interestingly, these compounds, in combination with Hydroxyflutamide, further suppressed the Adiol-induced AR transactivation. Reporter assays further showed that these four anti-Adiol steroids have relatively lower glucocorticoid, progesterone, and estrogenic activity. Together, these data suggest some selective steroids might have anti-Adiol activity, which may have potential clinical application in the battle against the androgen-dependent prostate cancer growth.
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Hydroxyflutamide may not always be a pure antiandrogen.
Lancet (London England), 1997Co-Authors: Shuyuan Yeh, Hiroshi Miyamoto, Chawnshang ChangAbstract:A and B: 1·5 μg wild-type hAR alone (columns 1, 2, 3, and 4) and cotransfected with 4·5 μg ARA70 (5, 6, 7, and 8) in the absence or presence of 10, 10, 10 mol/L of Hydroxyflutamide. C the mutant AR877 was used to replace the wild-type AR to perform the same experiment on panel B. All experiments were performed in human prostate cancer DU145 cells cultured in DMEM with 5% charcoalstripped fetal calf serum. In each transfection, 3·5 μg of PSA-ARE CAT (A) or MMTV-ARE CAT (B and C) were used as a reporter. The mock treatment of lane 1 was counted as standard one-fold. Relative CAT activity was calculated by the quantitation of phosphorimager. Data represent an average of at least three experiments. THE LANCET
Csaba Leranth - One of the best experts on this subject based on the ideXlab platform.
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Androgen Effects on Hippocampal CA1 Spine Synapse Numbers Are Retained in TfmMale Rats with Defective
2016Co-Authors: Androgen Receptors, Neil J. Maclusky, Tibor Hajszan, Jamie A. Johansen, Cynthia L. Jordan, Csaba LeranthAbstract:(DHT), or the antiandrogen Hydroxyflutamide on CA1 pyra-midal cell dendritic spine synapseswere investigated in adult male rats. To elucidate the contribution of the androgen re-ceptor to the hormone-induced increase in hippocampal CA1 synapses,wild-typemaleswere comparedwithmales express-ing the Tfm mutation, which results in synthesis of defective androgen receptors. Orchidectomized rats were treated with EB (10 g/ratd), DHT (500 g/ratd), Hydroxyflutamide (5 mg/ ratd), or the sesame oil vehicle sc daily for 2 d and examined using quantitative electron microscopic stereological tech-niques, 48 h after the second injection. In wild-type males, DHT and Hydroxyflutamide both induced increases in the number of spine synapses in the CA1 stratum radiatum, whereas EB had no effect. DHT almost doubled the number of synaptic contacts observed, whereas Hydroxyflutamide in
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Androgen Effects on Hippocampal CA1 Spine Synapse Numbers Are Retained in Tfm Male Rats with Defective Androgen Receptors
Endocrinology, 2006Co-Authors: Neil J. Maclusky, Tibor Hajszan, Jamie A. Johansen, Cynthia L. Jordan, Csaba LeranthAbstract:The effects of estradiol benzoate (EB), dihydrotestosterone (DHT), or the antiandrogen Hydroxyflutamide on CA1 pyramidal cell dendritic spine synapses were investigated in adult male rats. To elucidate the contribution of the androgen receptor to the hormone-induced increase in hippocampal CA1 synapses, wild-type males were compared with males expressing the Tfm mutation, which results in synthesis of defective androgen receptors. Orchidectomized rats were treated with EB (10 μg/rat·d), DHT (500 μg/rat·d), Hydroxyflutamide (5 mg/rat·d), or the sesame oil vehicle sc daily for 2 d and examined using quantitative electron microscopic stereological techniques, 48 h after the second injection. In wild-type males, DHT and Hydroxyflutamide both induced increases in the number of spine synapses in the CA1 stratum radiatum, whereas EB had no effect. DHT almost doubled the number of synaptic contacts observed, whereas Hydroxyflutamide increased synapse density by approximately 50%, compared with the vehicle-injecte...
Cor A Berrevoets - One of the best experts on this subject based on the ideXlab platform.
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Studies on the Human Prostatic Cell Line LNCaP Cancer
1994Co-Authors: Jos Veldscholte, Cor A Berrevoets, Eppo MulderAbstract:The effects of androgens, antiandrogens, and other steroid hormones on growth of the human prostate cancer cell line LNCaP were studied. Despite the absence of receptors for progesterone and estradiol, the growth rate of the androgen responsive LNCaP-FGC cells increased when cultured in the presence of either estrogens or progestagens. In addition, most antiandrogens were also growth stimulators. This aberrant response was due to a threonine to alanine substitution at amino acid position 868 in the steroid binding domain of the androgen receptor (AR). Only the antiandrogen ICI 176 334 could block transcription and cell growth by the mutant receptor. By immunoprecipitation of the AR from LNCaP cells with the specific antibody F39.4.1 and Western blotting, three types of heat-shock proteins co-precipitated: hsp90, hsp70 and hsp56. This co-isolation could be prevented by pre-incubating the cells with androgens or with the antiandrogen Hydroxyflutamide . Only the antiandrogen ICI 176 334 could block the effect of androgens on complex dissociation and prevent tight nuclear binding of the AR. Hydroxyflutamide could only inhibit tight nuclear binding of the wild-type AR. Therefore, in LNCaP cells the mutation in the steroid binding domain of the AR prevents a blockade of receptor function by most antiandrogens, but not by ICI 176 334, probably because of a different mechanism by which this compound blocks receptor function.
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Studies on the human prostatic cancer cell line LNCaP.
The Journal of steroid biochemistry and molecular biology, 1994Co-Authors: Jos Veldscholte, Cor A Berrevoets, Eppo MulderAbstract:The effects of androgens, antiandrogens, and other steroid hormones on growth of the human prostate cancer cell line LNCaP were studied. Despite the absence of receptors for progesterone and estradiol, the growth rate of the androgen responsive LNCaP-FGC cells increased when cultured in the presence of either estrogens or progestagens. In addition, most antiandrogens were also growth stimulators. This aberrant response was due to a threonine to alanine substitution at amino acid position 868 in the steroid binding domain of the androgen receptor (AR). Only the antiandrogen ICI 176,334 could block transcription and cell growth by the mutant receptor. By immunoprecipitation of the AR from LNCaP cells with the specific antibody F39.4.1 and Western blotting, three types of heat-shock proteins co-precipitated: hsp90, hsp70 and hsp56. This co-isolation could be prevented by pre-incubating the cells with androgens or with the antiandrogen Hydroxyflutamide. Only the antiandrogen ICI 176,334 could block the effect of androgens on complex dissociation and prevent tight nuclear binding of the AR. Hydroxyflutamide could only inhibit tight nuclear binding of the wild-type AR. Therefore, in LNCaP cells the mutation in the steroid binding domain of the AR prevents a blockade of receptor function by most antiandrogens, but not by ICI 176,334, probably because of a different mechanism by which this compound blocks receptor function.
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EFFECTS OF ANTIANDROGENS ON TRANSFORMATION AND TRANSCRIPTION ACTIVATION OF WILD-TYPE AND MUTATED (LNCaP) ANDROGEN RECEPTORS
The Journal of steroid biochemistry and molecular biology, 1993Co-Authors: Cor A Berrevoets, Jos Veldscholte, Eppo MulderAbstract: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.
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Anti-androgens and the mutated androgen receptor of LNCaP cells: differential effects on binding affinity, heat-shock protein interaction, and transcription activation.
Biochemistry, 1992Co-Authors: Jos Veldscholte, Cor A Berrevoets, Albert O. Brinkmann, J. Anton Grootegoed, Eppo MulderAbstract:Previous studies from this laboratory have described that LNCaP prostate tumor cells contain an androgen receptor (AR) with a point mutation in the steroid-binding domain (codon 868, Thr to Ala). This defect leads to a change in specificity of the AR. Estrogens, progestagens, and some anti-androgens (e.g., cyproterone acetate, Hydroxyflutamide, nilutamide) stimulate LNCaP cell growth rate through the AR. The present studies indicate that not all anti-androgens showed agonistic effects with the mutated receptor. The growth rate of LNCaP cells did not increase with the anti-androgen ICI 176334, nor could this compound increase transcription activation of the reporter gene construct via the mutant receptor in a cotransfection system [HeLa cell cotransfection system with an androgen-regulated reporter gene construct (pG29G-tk-CAT) and the mutant receptor as trans-vector]. Interaction of the AR of LNCaP cells with heat-shock proteins was studied by isolation of the receptor with a specific monoclonal antibody and characterization of associated proteins. Hsp90, hsp70, and hsp56 were found to coprecipitate with the AR. Incubation of the cells at 37 degrees C with androgen (R1881, 10 nM) or the anti-androgen Hydroxyflutamide, prior to receptor isolation, resulted in dissociation of the AR-heat-shock protein complex. This dissociation is paralleled by the transformation to a tight nuclear-binding form of the AR. In contrast, ICI 176334 could not induce a release of heat-shock proteins and did not increase nuclear binding, but inhibited the transformation process induced by R1881.(ABSTRACT TRUNCATED AT 250 WORDS)
