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Androgen receptor suppresses β-adrenoceptor-mediated CREB activation and thermogenesis in brown adipose tissue of male mice. J Biol Chem 2022; 298:102619. [PMID: 36272644 PMCID: PMC9700029 DOI: 10.1016/j.jbc.2022.102619] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 10/13/2022] [Accepted: 10/14/2022] [Indexed: 11/07/2022] Open
Abstract
Thermoregulation is a process by which core body temperature is maintained in mammals. Males typically have a lower body temperature than females. However, the effects of androgens, which show higher levels in males, on adrenergic receptor-mediated thermogenesis remain unclear. Here, we demonstrate that androgen-androgen receptor (AR) signaling suppresses the β-adrenergic agonist-induced rise of core body temperature using castrated and AR knockout (ARKO) male mice. Furthermore, in vitro mechanistic studies show that activated AR inhibits cAMP response element (CRE)-mediated transcription by suppressing cAMP response element-binding protein (CREB) phosphorylation. The elevation of body temperature induced by the β-adrenergic agonist CL316243 was higher in ARKO and castrated mice than in the control mice. Similarly, CL316243 induced a greater increase in Uncoupling protein 1 (Ucp1) expression and CREB phosphorylation in the brown adipose tissue of ARKO mice than in that of controls. We determined that activation of AR by dihydrotestosterone suppressed β3-agonist- or forskolin-induced CRE-mediated transcription, which was prevented by AR antagonist. AR activation also suppressed CREB phosphorylation induced by forskolin. Moreover, we found AR nuclear localization, but not transcriptional activity, was necessary for the suppression of CRE-mediated transcription. Finally, modified mammalian two-hybrid and immunoprecipitation analyses suggest nuclear AR and CREB form a protein complex both in the presence and absence of dihydrotestosterone and forskolin. These results suggest androgen-AR signaling suppresses β-adrenoceptor-induced UCP1-mediated brown adipose tissue thermogenesis by suppressing CREB phosphorylation, presumably owing to a protein complex with AR and CREB. This mechanism explains sexual differences in body temperature, at least partially.
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2
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Shen D, Ju L, Zhou F, Yu M, Ma H, Zhang Y, Liu T, Xiao Y, Wang X, Qian K. The inhibitory effect of melatonin on human prostate cancer. Cell Commun Signal 2021; 19:34. [PMID: 33722247 PMCID: PMC7962396 DOI: 10.1186/s12964-021-00723-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/10/2021] [Indexed: 12/15/2022] Open
Abstract
Prostate cancer (PCa) is one of the most commonly diagnosed human cancers in males. Nearly 191,930 new cases and 33,330 new deaths of PCa are estimated in 2020. Androgen and androgen receptor pathways played essential roles in the pathogenesis of PCa. Androgen depletion therapy is the most used therapies for primary PCa patients. However, due to the high relapse and mortality of PCa, developing novel noninvasive therapies have become the focus of research. Melatonin is an indole-like neurohormone mainly produced in the human pineal gland with a prominent anti-oxidant property. The anti-tumor ability of melatonin has been substantially confirmed and several related articles have also reported the inhibitory effect of melatonin on PCa, while reviews of this inhibitory effect of melatonin on PCa in recent 10 years are absent. Therefore, we systematically discuss the relationship between melatonin disruption and the risk of PCa, the mechanism of how melatonin inhibited PCa, and the synergistic benefits of melatonin and other drugs to summarize current understandings about the function of melatonin in suppressing human prostate cancer. We also raise several unsolved issues that need to be resolved to translate currently non-clinical trials of melatonin for clinic use. We hope this literature review could provide a solid theoretical basis for the future utilization of melatonin in preventing, diagnosing and treating human prostate cancer. Video abstract
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Affiliation(s)
- Dexin Shen
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Lingao Ju
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China.,Human Genetics Resource Preservation Center of Hubei Province, Wuhan, China.,Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
| | - Fenfang Zhou
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Mengxue Yu
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China.,Human Genetics Resource Preservation Center of Hubei Province, Wuhan, China.,Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
| | - Haoli Ma
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China.,Cancer Precision Diagnosis and Treatment and Translational Medicine, Hubei Engineering Research Center, Wuhan, China.,Emergency Center, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yi Zhang
- Center for Life Sciences, Peking University, Beijing, China.,Peking-Tsinghua Center of Life Sciences, Beijing, China.,Euler Technology, ZGC Life Sciences Park, Beijing, China
| | - Tongzu Liu
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
| | - Yu Xiao
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China. .,Human Genetics Resource Preservation Center of Hubei Province, Wuhan, China. .,Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China.
| | - Xinghuan Wang
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China. .,Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China. .,Medical Research Institute, Wuhan University, Wuhan, China.
| | - Kaiyu Qian
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China. .,Human Genetics Resource Preservation Center of Hubei Province, Wuhan, China. .,Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China.
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3
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Phasing the intranuclear organization of steroid hormone receptors. Biochem J 2021; 478:443-461. [DOI: 10.1042/bcj20200883] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/28/2020] [Accepted: 01/07/2021] [Indexed: 12/15/2022]
Abstract
Steroid receptors (SRs) encompass a family of transcription factors that regulate the expression of thousands of genes upon binding to steroid hormones and include the glucocorticoid, androgen, progesterone, estrogen and mineralocorticoid receptors. SRs control key physiological and pathological processes, thus becoming relevant drug targets. As with many other nuclear proteins, hormone-activated SRs concentrate in multiple discrete foci within the cell nucleus. Even though these foci were first observed ∼25 years ago, their exact structure and function remained elusive. In the last years, new imaging methodologies and theoretical frameworks improved our understanding of the intranuclear organization. These studies led to a new paradigm stating that many membraneless nuclear compartments, including transcription-related foci, form through a liquid–liquid phase separation process. These exciting ideas impacted the SR field by raising the hypothesis of SR foci as liquid condensates involved in transcriptional regulation. In this work, we review the current knowledge about SR foci formation under the light of the condensate model, analyzing how these structures may impact SR function. These new ideas, combined with state-of-the-art techniques, may shed light on the biophysical mechanisms governing the formation of SR foci and the biological function of these structures in normal physiology and disease.
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4
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Schuppe ER, Miles MC, Fuxjager MJ. Evolution of the androgen receptor: Perspectives from human health to dancing birds. Mol Cell Endocrinol 2020; 499:110577. [PMID: 31525432 DOI: 10.1016/j.mce.2019.110577] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/04/2019] [Accepted: 09/09/2019] [Indexed: 12/23/2022]
Abstract
Androgenic hormones orchestrate the development and activation of diverse reproductive phenotypes across vertebrates. Although extensive work investigates how selection for these traits modifies individual elements of this signaling system (e.g., hormone or androgen receptor [AR] levels), we know less about natural variation in the AR sequence across vertebrates. Our knowledge of AR sequence mutations is largely limited to work in human patients or cell-lines, providing a framework to contextualize single mutations at the expense of evolutionary timescale. Here we unite both perspectives in a review that explores the functional significance of AR on a domain-by-domain basis, using existing knowledge to highlight how and why each region might evolve. We then examine AR sequence variation on different timescales by examining sequence variation in clades originating in the Cambrian (vertebrates; >500 mya) and Cretaceous (birds; >65 mya). In each case, we characterize how the receptor has changed over time and discuss which regions are most likely to evolve in response to selection. Overall, domains that are required for androgenic signaling to function (e.g., DNA- and ligand-binding) tend to be conserved. Meanwhile, areas that interface with co-regulatory molecules can exhibit notable variation even between closely related species. We propose that accumulating mutations in regulatory regions is one way that AR structure might act as a substrate for selection to guide the evolution of reproductive traits. By synthesizing literature across disciplines and highlighting the evolutionary potential of specific AR regions, we hope to inspire new avenues of integrative research into endocrine system evolution.
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Affiliation(s)
- Eric R Schuppe
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
| | - Meredith C Miles
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA
| | - Matthew J Fuxjager
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA.
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5
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Schuppe ER, Fuxjager MJ. Phenotypic variation reveals sites of evolutionary constraint in the androgenic signaling pathway. Horm Behav 2019; 115:104538. [PMID: 31211944 DOI: 10.1016/j.yhbeh.2019.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/19/2019] [Accepted: 06/10/2019] [Indexed: 01/05/2023]
Abstract
Steroid hormone systems play an important role in shaping the evolution of vertebrate sexual traits, but several aspects of this relationship remain unclear. For example, we currently know little about how steroid signaling complexes are adapted to accommodate the emergence of behavior in response to sexual selection. We use downy woodpeckers (Dryobates pubescens) to evaluate how the machinery underlying androgen action can evolve to accommodate this bird's main territorial signal, the drum. We focus specifically on modifications to androgenic mechanisms in the primary neck muscle that actuates the hammering movements underlying this signal. Of the signaling components we examine, we find that levels of circulating testosterone (T) and androgen receptor (AR) expression are consistently increased in a way that likely enhances androgenic regulation of drumming. By contrast, the expression of nuclear receptor co-factors-the 'molecular rheostats' of steroid action-show no such relationship in our analyses. If anything, co-factors are expressed in directions that would presumably hinder androgenic regulation of the drum. These findings therefore collectively point to T levels and AR as the more evolutionarily labile components of the androgenic system, in that they are likely more apt to change over time to support sexual selection for territorial signaling in woodpeckers. Yet the signaling elements that fine-tune AR's functional effects on the genome-namely the receptor's transcriptional co-factors-do not change in such a manner, and thus may be under tighter evolutionary constraint.
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Affiliation(s)
- Eric R Schuppe
- Department of Biology, Wake Forest University, 455 Vine Street, Winston-Salem, NC 27101, United States of America
| | - Matthew J Fuxjager
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, United States of America.
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6
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Cai Z, Chen W, Zhang J, Li H. Androgen receptor: what we know and what we expect in castration-resistant prostate cancer. Int Urol Nephrol 2018; 50:1753-1764. [PMID: 30128923 DOI: 10.1007/s11255-018-1964-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/14/2018] [Indexed: 12/17/2022]
Abstract
Androgen deprivation therapy is an important therapy for prostate cancer (PCa) in aging men. Under the background of castration, it is inevitable that prostate cancer will develop into castration-resistant prostate cancer (CRPC), which has a high mortality rate, after 2-3 years. Androgen receptor (AR) plays a key role in PCa development and is essential to CRPC. More recent research studies have reported that the development of CRPC is largely due to altered mechanisms related to AR, so it is important for us to understand the roles of AR and detailed AR-related mechanisms in CRPC. The multiple AR-related mechanisms promoting the development of CRPC are as follows: (1) enhanced transformation and increased synthesis of intratumoral androgen; (2) AR overexpression, which enables CRPC to be hypersensitive to low levels of androgen; (3) AR cofactors, which enhanced AR transactivation; (4) AR-spliced variants, which mediated downstream gene expression without androgen; (5) the interaction between the AR pathway and classic tumor-related pathways; and» (6) AR mutations, which reduced AR specificity and enhanced AR transcription.
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Affiliation(s)
- Zhonglin Cai
- Department of Urology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, 1 Shuaifuyuan, Dongcheng District, Beijing, 100730, China
| | - Weijie Chen
- Department of Urology, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai Traditional Chinese Medicine University, Shanghai, China
| | - Jianzhong Zhang
- Department of Urology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, 1 Shuaifuyuan, Dongcheng District, Beijing, 100730, China
| | - Hongjun Li
- Department of Urology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, 1 Shuaifuyuan, Dongcheng District, Beijing, 100730, China.
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CUDC-101, a Novel Inhibitor of Full-Length Androgen Receptor (flAR) and Androgen Receptor Variant 7 (AR-V7) Activity: Mechanism of Action and In Vivo Efficacy. Discov Oncol 2016; 7:196-210. [PMID: 26957440 DOI: 10.1007/s12672-016-0257-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/12/2016] [Indexed: 12/29/2022] Open
Abstract
Castration-resistant prostate cancer (CRPC) is an androgen receptor (AR)-dependent disease expected to cause the death of more than 27,000 Americans in 2015. There are only a few available treatments for CRPC, making the discovery of new drugs an urgent need. We report that CUDC-101 (an inhibitor od HER2/NEU, EGFR and HDAC) inhibits both the full length AR (flAR) and the AR variant AR-V7. This observation prompted experiments to discover which of the known activities of CUDC-101 is responsible for the inhibition of flAR/AR-V7 signaling. We used pharmacologic and genetic approaches, and found that the effect of CUDC-101 on flAR and AR-V7 was duplicated only by other HDAC inhibitors, or by silencing the HDAC isoforms HDAC5 and HDAC10. We observed that CUDC-101 treatment or AR-V7 silencing by RNAi equally reduced transcription of the AR-V7 target gene, PSA, without affecting viability of 22Rv1 cells. However, when cellular proliferation was used as an end point, CUDC-101 was more effective than AR-V7 silencing, raising the prospect that CUDC-101 has additional targets beside AR-V7. In support of this, we found that CUDC-101 increased the expression of the cyclin-dependent kinase inhibitor p21, and decreased that of the oncogene HER2/NEU. To determine if CUDC-101 reduces growth in a xenograft model of prostate cancer, this drug was given for 14 days to castrated male SCID mice inoculated with 22Rv1 cells. Compared to vehicle, CUDC-101 reduced xenograft growth in a statistically significant way, and without macroscopic side effects. These studies demonstrate that CUDC-101 inhibits wtAR and AR-V7 activity and growth of 22Rv1 cells in vitro and in vivo. These effects result from the ability of CUDC-101 to target not only HDAC signaling, which was associated with decreased flAR and AR-V7 activity, but multiple additional oncogenic pathways. These observations raise the possibility that treatment of CRPC may be achieved by using similarly multi-targeted approaches.
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8
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Harada N, Katsuki T, Takahashi Y, Masuda T, Yoshinaga M, Adachi T, Izawa T, Kuwamura M, Nakano Y, Yamaji R, Inui H. Androgen receptor silences thioredoxin-interacting protein and competitively inhibits glucocorticoid receptor-mediated apoptosis in pancreatic β-Cells. J Cell Biochem 2016; 116:998-1006. [PMID: 25639671 DOI: 10.1002/jcb.25054] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 12/18/2014] [Indexed: 01/09/2023]
Abstract
Androgen receptor (AR) is known to bind to the same cis-element that glucocorticoid receptor (GR) binds to. However, the effects of androgen signaling on glucocorticoid signaling have not yet been elucidated. Here, we investigated the effects of testosterone on dexamethasone (DEX, a synthetic glucocorticoid)-induced apoptosis of pancreatic β-cells, which might be involved in the pathogenesis of type 2 diabetes mellitus in males. We used INS-1 #6 cells, which were isolated from the INS-1 pancreatic β-cell line and which express high levels of AR. Testosterone and dihydrotestosterone inhibited apoptosis induced by DEX in INS-1 #6 cells. AR knockdown and the AR antagonist hydroxyflutamide each diminished the anti-apoptotic effects of testosterone. AR was localized in the nucleus of both INS-1 #6 cells and pancreatic β-cells of male rats. Induction of thioredoxin-interacting protein (TXNIP) is known to cause pro-apoptotic effects in β-cells. Testosterone suppressed the DEX-induced increase of TXNIP at the transcriptional level. A Chromatin immunoprecipitation assays showed that both AR and GR competitively bound to the TXNIP promoter in ligand-dependent manners. Recombinant DNA-binding domain of AR bound to the same cis-element of the TXNIP promoter that GR binds to. Our results show that AR and GR competitively bind to the same cis-element of TXNIP promoter as a silencer and enhancer, respectively. These results indicate that androgen signaling functionally competes with glucocorticoid signaling in pancreatic β-cell apoptosis.
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Affiliation(s)
- Naoki Harada
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka, 5998531, Japan
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Abstract
Androgen insensitivity syndrome (AIS) results from androgen receptor dysfunction and is a common cause of disorder of sex development. The AIS phenotype largely depends on the degree of residual androgen receptor (AR) activity. This review describes the molecular action of androgens and the range of androgen receptor gene mutations, essential knowledge to understand the pathogenesis of the complete and partial forms of this syndrome. A multidisciplinary approach is recommended for clinical management from infancy through to adulthood. Hormone replacement therapy is needed following gonadectomy. Patients who choose to retain the gonads are at risk of developing germ cell tumors for which sensitive circulating tumor markers may soon become available. Whilst the contribution of AR dysfunction to complete AIS is well understood, the involvement of the AR and associated proteins as contributors to partial AIS is an area of active research. Disorders of sex development such as AIS which are related to AR dysfunction offer a breadth of manifestations for the clinician to manage and opportunities for further research on the mechanism of androgen action.
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Affiliation(s)
- Nigel P Mongan
- Cancer Biology and Translational Research, Faculty of Medicine and Health Sciences, School of Veterinary Medicine and Science, University of Nottingham, UK
| | - Rieko Tadokoro-Cuccaro
- Department of Paediatrics, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, UK
| | - Trevor Bunch
- Department of Paediatrics, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, UK
| | - Ieuan A Hughes
- Department of Paediatrics, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, UK.
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10
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Campana C, Pezzi V, Rainey WE. Cell-based assays for screening androgen receptor ligands. Semin Reprod Med 2015; 33:225-34. [PMID: 26036905 DOI: 10.1055/s-0035-1552989] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The androgen receptor (AR, NR3C4) mediates the majority of androgen effects on target cells. The AR is activated following ligand binding that result is enhanced of target gene transcription. Several cell-based model systems have been developed that allow sensitive detection and monitoring of steroids or other compounds with AR bioactivity. Most cell-based AR reporter models use transgenic gene constructs that include an androgen response element that controls reporter gene expression. The DNA cis-regulatory elements that respond to AR share sequence similarity with cis-regulatory elements for glucocorticoid (GR, NR3C1), mineralocorticoid (MR, NR3C2), and progesterone (PGR, NR3C3) receptors, which has compromised AR selectivity for some models. In recent years, the sensitivity and selectivity of AR bioassays have been significantly improved through careful selection of cell models, utilization of improved reporter genes, and the use of yeast two-hybrid AR systems. This review summarizes and compares the currently available androgen-responsive cell model systems.
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Affiliation(s)
- Carmela Campana
- Departments of Molecular and Integrative Physiology and Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
| | - Vincenzo Pezzi
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende (CS), Italy
| | - William E Rainey
- Departments of Molecular and Integrative Physiology and Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan
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11
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Zhao K, Li S, Wu L, Lai C, Yang G. Hydrogen sulfide represses androgen receptor transactivation by targeting at the second zinc finger module. J Biol Chem 2015; 289:20824-35. [PMID: 24942741 DOI: 10.1074/jbc.m114.559518] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Androgen receptor (AR) signaling is indispensable for the development of prostate cancer from the initial androgen-dependent state to a later aggressive androgen-resistant state. This study examined the role of hydrogen sulfide (H(2)S), a novel gasotransmitter, in the regulation of AR signaling as well as its mediation in androgen-independent cell growth in prostate cancer cells. Here we found that H(2)S inhibits cell proliferation of both androgen-dependent (LNCaP) and antiandrogen-resistant prostate cancer cells (LNCaP-B), with more significance on the latter, which was established by long term treatment of parental LNCaP cells with bicalutamide. The expression of cystathionine γ-lyase (CSE), a major H(2)S producing enzyme in prostate tissue, was reduced in both human prostate cancer tissues and LNCaP-B cells. LNCaP-B cells were resistant to bicalutamide-induced cell growth inhibition, and CSE overexpression could rebuild the sensitivity of LNCaP-B cells to bicalutamide. H(2)S significantly repressed the expression of prostate-specific antigen (PSA) and TMPRSS2, two AR-targeted genes. In addition, H(2)S inhibited AR binding with PSA promoter and androgen-responsive element (ARE) luciferase activity. We further found that AR is post-translationally modified by H(2)S through S-sulfhydration. Mutation of cysteine 611 and cysteine 614 in the second zinc finger module of AR-DNA binding domain diminished the effects of H(2)S on AR S-sulfhydration and AR dimerization. These data suggest that reduced CSE/H2S signaling contributes to antiandrogen-resistant status, and sufficient level of H(2)S is able to inhibit AR transactivation and treat castration-resistant prostate cancer.
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12
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Dar JA, Masoodi KZ, Eisermann K, Isharwal S, Ai J, Pascal LE, Nelson JB, Wang Z. The N-terminal domain of the androgen receptor drives its nuclear localization in castration-resistant prostate cancer cells. J Steroid Biochem Mol Biol 2014; 143:473-80. [PMID: 24662325 PMCID: PMC4127361 DOI: 10.1016/j.jsbmb.2014.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 02/14/2014] [Accepted: 03/14/2014] [Indexed: 10/25/2022]
Abstract
Androgen-independent nuclear localization is required for androgen receptor (AR) transactivation in castration-resistant prostate cancer (CRPC) and should be a key step leading to castration resistance. However, mechanism(s) leading to androgen-independent AR nuclear localization are poorly understood. Since the N-terminal domain (NTD) of AR plays a role in transactivation under androgen-depleted conditions, we investigated the role of the NTD in AR nuclear localization in CRPC. Deletion mutagenesis was used to identify amino acid sequences in the NTD essential for its androgen-independent nuclear localization in C4-2, a widely used CRPC cell line. Deletion mutants of AR tagged with green fluorescent protein (GFP) at the 5'-end were generated and their signal distribution was investigated in C4-2 cells by fluorescent microscopy. Our results showed that the region of a.a. 294-556 was required for androgen-independent AR nuclear localization whereas a.a. 1-293 mediates Hsp90 regulation of AR nuclear localization in CRPC cells. Although the region of a.a. 294-556 does not contain a nuclear import signal, it was able to enhance DHT-induced import of the ligand binding domain (LBD). Also, transactivation of the NTD could be uncoupled from its modulation of AR nuclear localization in C4-2 cells. These observations suggest an important role of the NTD in AR intracellular trafficking and androgen-independent AR nuclear localization in CRPC cells.
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Affiliation(s)
- Javid A Dar
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States; Central Laboratory College of Science, King Saud University, Riyadh KSA-11451, Saudi Arabia
| | - Khalid Z Masoodi
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States
| | - Kurtis Eisermann
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States
| | - Sudhir Isharwal
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States
| | - Junkui Ai
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States
| | - Laura E Pascal
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States
| | - Joel B Nelson
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States; University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States
| | - Zhou Wang
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States; Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, United States; University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, United States.
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13
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Kim JS, Roberts JM, Bingman WE, Shao L, Wang J, Ittmann MM, Weigel NL. The prostate cancer TMPRSS2:ERG fusion synergizes with the vitamin D receptor (VDR) to induce CYP24A1 expression-limiting VDR signaling. Endocrinology 2014; 155:3262-73. [PMID: 24926821 PMCID: PMC5377584 DOI: 10.1210/en.2013-2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A number of preclinical studies have shown that the activation of the vitamin D receptor (VDR) reduces prostate cancer (PCa) cell and tumor growth. The majority of human PCas express a transmembrane protease serine 2 (TMPRSS2):erythroblast transformation-specific (ETS) fusion gene, but most preclinical studies have been performed in PCa models lacking TMPRSS2:ETS in part due to the limited availability of model systems expressing endogenous TMPRSS2:ETS. The level of the active metabolite of vitamin D, 1α,25-dihydroxyvitamin D3 (1,25D), is controlled in part by VDR-dependent induction of cytochrome P450, family 24, subfamily 1, polypeptide1 (CYP24A1), which metabolizes 1,25D to an inactive form. Because ETS factors can cooperate with VDR to induce rat CYP24A1, we tested whether TMPRSS2:ETS would cause aberrant induction of human CYP24A1 limiting the activity of VDR. In TMPRSS2:ETS positive VCaP cells, depletion of TMPRSS2:ETS substantially reduced 1,25D-mediated CYP24A1 induction. Artificial expression of the type VI+72 TMPRSS2:ETS isoform in LNCaP cells synergized with 1,25D to greatly increase CYP24A1 expression. Thus, one of the early effects of TMPRSS2:ETS in prostate cells is likely a reduction in intracellular 1,25D, which may lead to increased proliferation. Next, we tested the net effect of VDR action in TMPRSS2:ETS containing PCa tumors in vivo. Unlike previous animal studies performed on PCa tumors lacking TMPRSS2:ETS, EB1089 (seocalcitol) (a less calcemic analog of 1,25D) did not inhibit the growth of TMPRSS2:ETS containing VCaP tumors in vivo, suggesting that the presence of TMPRSS2:ETS may limit the growth inhibitory actions of VDR. Our findings suggest that patients with TMPRSS2:ETS negative tumors may be more responsive to VDR-mediated growth inhibition and that TMPRSS2:ETS status should be considered in future clinical trials.
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Affiliation(s)
- Jung-Sun Kim
- Departments of Molecular and Cellular Biology (J.-S.K., J.M.R., W.E.B., N.L.W.) and Pathology and Immunology (L.S., J.W., M.M.I.), Baylor College of Medicine, Houston, Texas 77030
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14
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Mass spectrometric determination of disulfide bonds in the biologically active recombinant HBx protein of hepatitis B virus. Biochemistry 2014; 53:4685-95. [PMID: 24971648 DOI: 10.1021/bi500140t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Many proteins rely on disulfide bonds formed between pairs of cysteines for the stability of their folded state and to keep regulatory control over their functions. The hepatitis B virus-encoded HBx oncoprotein is known to perform an overwhelming array of functions in the cell and has been implicated in the development of hepatocellular carcinoma. However, its structure has not been elucidated. HBx carries nine conserved cysteine residues that have proven to be crucial for its various functions. However, the status of disulfide bonds between the cysteine residues reported in previous studies remains discrepant because of the use of refolded recombinant HBx that may contain non-native disulfides. Now we have determined the disulfide linkages in soluble and biologically active recombinant maltose binding protein-HBx fusion protein using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. We report four disulfide linkages in HBx protein, viz., between Cys(7) and Cys(69), Cys(61) and Cys(115), Cys(78) and Cys(137), and Cys(17) and Cys(143), based on the differential mobility of corresponding disulfide-linked peptide ions under reducing and nonreducing conditions. Cys(148) was observed to be free. Site-directed mutagenesis of Cys(143) and Cys(148) with serine and functional analyses of these mutants affirmed the importance of these residues in the ability of HBx to potentiate Cdk2/cyclin E kinase activity and transcriptionally activate promoter reporter gene activity. Thus, this study identifies native disulfide linkages in the structure of a biologically active viral oncoprotein.
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15
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Androgen receptor and its splice variant, AR-V7, differentially regulate FOXA1 sensitive genes in LNCaP prostate cancer cells. Int J Biochem Cell Biol 2014; 54:49-59. [PMID: 25008967 DOI: 10.1016/j.biocel.2014.06.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 05/25/2014] [Accepted: 06/18/2014] [Indexed: 11/23/2022]
Abstract
Prostate cancer (PCa) is an androgen-dependent disease, and tumors that are resistant to androgen ablation therapy often remain androgen receptor (AR) dependent. Among the contributors to castration-resistant PCa are AR splice variants that lack the ligand-binding domain (LBD). Instead, they have small amounts of unique sequence derived from cryptic exons or from out of frame translation. The AR-V7 (or AR3) variant is constitutively active and is expressed under conditions consistent with CRPC. AR-V7 is reported to regulate a transcriptional program that is similar but not identical to that of AR. However, it is unknown whether these differences are due to the unique sequence in AR-V7, or simply to loss of the LBD. To examine transcriptional regulation by AR-V7, we have used lentiviruses encoding AR-V7 (amino acids 1-627 of AR with the 16 amino acids unique to the variant) to prepare a derivative of the androgen-dependent LNCaP cells with inducible expression of AR-V7. An additional cell line was generated with regulated expression of AR-NTD (amino acids 1-660 of AR); this mutant lacks the LBD but does not have the AR-V7 specific sequence. We find that AR and AR-V7 have distinct activities on target genes that are co-regulated by FOXA1. Transcripts regulated by AR-V7 were similarly regulated by AR-NTD, indicating that loss of the LBD is sufficient for the observed differences. Differential regulation of target genes correlates with preferential recruitment of AR or AR-V7 to specific cis-regulatory DNA sequences providing an explanation for some of the observed differences in target gene regulation.
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16
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Androgens and the androgen receptor (AR). Mol Oncol 2013. [DOI: 10.1017/cbo9781139046947.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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17
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Chang C, Yeh S, Lee SO, Chang TM. Androgen receptor (AR) pathophysiological roles in androgen-related diseases in skin, bone/muscle, metabolic syndrome and neuron/immune systems: lessons learned from mice lacking AR in specific cells. NUCLEAR RECEPTOR SIGNALING 2013; 11:e001. [PMID: 24653668 PMCID: PMC3960937 DOI: 10.1621/nrs.11001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 05/28/2013] [Indexed: 12/19/2022]
Abstract
The androgen receptor (AR) is expressed ubiquitously and plays a variety of roles in a vast number of physiological and pathophysiological processes. Recent studies of AR knockout (ARKO) mouse models, particularly the cell type- or tissue-specific ARKO models, have uncovered many AR cell type- or tissue-specific pathophysiological roles in mice, which otherwise would not be delineated from conventional castration and androgen insensitivity syndrome studies. Thus, the AR in various specific cell types plays pivotal roles in production and maturation of immune cells, bone mineralization, and muscle growth. In metabolism, the ARs in brain, particularly in the hypothalamus, and the liver appear to participate in regulation of insulin sensitivity and glucose homeostasis. The AR also plays key roles in cutaneous wound healing and cardiovascular diseases, including atherosclerosis and abdominal aortic aneurysm. This article will discuss the results obtained from the total, cell type-, or tissue-specific ARKO models. The understanding of AR cell type- or tissue-specific physiological and pathophysiological roles using these in
vivo mouse models will provide useful information in uncovering AR roles in humans and eventually help us to develop better therapies via targeting the AR or its downstream signaling molecules to combat androgen/AR-related diseases.
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Affiliation(s)
- Chawnshang Chang
- George Whipple Lab for Cancer Research, Departments of Pathology, Urology, Radiation Oncology, and the Wilmot Cancer Center, University of Rochester Medical Center, Rochester, New York, USA (CC, SY, SOL, T-MC) and Sex Hormone Research Center, China Medical University/Hospital, Taichung, Taiwan (CC)
| | - Shuyuan Yeh
- George Whipple Lab for Cancer Research, Departments of Pathology, Urology, Radiation Oncology, and the Wilmot Cancer Center, University of Rochester Medical Center, Rochester, New York, USA (CC, SY, SOL, T-MC) and Sex Hormone Research Center, China Medical University/Hospital, Taichung, Taiwan (CC)
| | - Soo Ok Lee
- George Whipple Lab for Cancer Research, Departments of Pathology, Urology, Radiation Oncology, and the Wilmot Cancer Center, University of Rochester Medical Center, Rochester, New York, USA (CC, SY, SOL, T-MC) and Sex Hormone Research Center, China Medical University/Hospital, Taichung, Taiwan (CC)
| | - Ta-Min Chang
- George Whipple Lab for Cancer Research, Departments of Pathology, Urology, Radiation Oncology, and the Wilmot Cancer Center, University of Rochester Medical Center, Rochester, New York, USA (CC, SY, SOL, T-MC) and Sex Hormone Research Center, China Medical University/Hospital, Taichung, Taiwan (CC)
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18
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Muramatsu K, Matsui H, Sekine Y, Koike H, Shibata Y, Ito K, Suzuki K. Androgen receptor coactivator p120 subtype β is highly expressed in prostate cancer. Prostate Int 2013; 1:10-5. [PMID: 24223396 PMCID: PMC3821517 DOI: 10.12954/pi.12004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Accepted: 02/03/2013] [Indexed: 11/29/2022] Open
Abstract
Purpose: The β form of p120 is reported to be a strong coactivator of the androgen receptor. We investigated the gene expression profiles of the α and β forms of p120 in prostate cancer cell lines, benign prostatic hyperplasia (BPH), nontreated prostate cancer (NTPC), and prostate cancer after androgen deprivation therapy (PCA-ADT). Methods: We obtained 154 prostate needle biopsy specimens (81 in BPH, 51 in NTPC, and 22 in PCA-ADT). Levels of p120α and β expression were determined by multiplex real-time polymerase chain reaction. Results: Prostate cancer cell lines, LNCaP, PC-3, DU-145, and LNCaP-LA, which is a derivative of LNCaP under androgen deprivation, expressed both p120α and p120β. p120α expression levels were significantly higher than those of p120β in all cell lines examined. In human prostate tissues, p120α expression was significantly higher than that of p120β in BPH and NTPC. p120α expression in BPH was significantly higher than in other groups. In contrast, p120β expression was significantly higher in NTPC and PCA-ADT than in BPH. Expression of the two forms of p120 was not correlated with age, prostate-specific antigen, or Gleason score. Conclusions: The expression profiles of p120α and p120β significantly differ in cancerous and benign prostatic tissues.
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Affiliation(s)
- Kazumichi Muramatsu
- Department of Urology, Gunma University Graduate School of Medicine, Maebashi, Japan
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19
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Targeted disruption of the p160 coactivator interface of androgen receptor (AR) selectively inhibits AR activity in both androgen-dependent and castration-resistant AR-expressing prostate cancer cells. Int J Biochem Cell Biol 2012; 45:763-72. [PMID: 23270728 DOI: 10.1016/j.biocel.2012.12.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 11/24/2012] [Accepted: 12/13/2012] [Indexed: 10/27/2022]
Abstract
The evidence that androgen blockade-resistant prostate cancer, termed castration resistant, remains androgen receptor (AR) dependent is compelling. AR is re-activated through multiple mechanisms including expression of constitutively active splice variants that lack hormone binding domains (HBDs). This highlights the need to develop therapies that target regions other than the HBD. Because the p160 coactivators interact most strongly with the amino-terminus of AR, we examined the consequences of disrupting this interaction. We identified two overlapping SRC-1 peptides that interact with AR, but not with progesterone receptor. These peptides reduce AR and AR variant AR-V7 dependent induction of an AR responsive reporter. Using mammalian two hybrid assays, we found that the peptides interrupt the AR/SRC-1, AR/SRC-2 and AR N/C interactions, but not SRC-1/CARM-1 interactions. Consistent with the SRC-1 dependence of induced, but not repressed genes, in LNCaP cells, the peptides inhibited hormone dependent induction of endogenous target genes including PSA and TMPRSS2, but did not block AR dependent repression of UGT2B17 or inhibit vitamin D receptor activity. Simultaneous detection of SRC-1 peptides and PSA by double immunofluorescence in transfected LNCaP cells clearly demonstrated a strong reduction in PSA levels in cells expressing the peptides. The peptides also inhibited the AR dependent expression of PSA in castration resistant C4-2 cells. Moreover they inhibited androgen dependent proliferation of LNCaP cells and proliferation of C4-2 cells in androgen depleted medium without affecting AR negative PC-3 cells. Thus, the p160 coactivator binding site is a novel potential therapeutic target to inhibit AR activity.
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20
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He S, Zhang C, Shafi AA, Sequeira M, Acquaviva J, Friedland JC, Sang J, Smith DL, Weigel NL, Wada Y, Proia DA. Potent activity of the Hsp90 inhibitor ganetespib in prostate cancer cells irrespective of androgen receptor status or variant receptor expression. Int J Oncol 2012; 42:35-43. [PMID: 23152004 PMCID: PMC3583620 DOI: 10.3892/ijo.2012.1698] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 10/10/2012] [Indexed: 11/05/2022] Open
Abstract
Androgen ablation therapy represents the first line of therapeutic intervention in men with advanced or recurrent prostate tumors. However, the incomplete efficacy and lack of durable response to this clinical strategy highlights an urgent need for alternative treatment options to improve patient outcomes. Targeting the molecular chaperone heat shock protein 90 (Hsp90) represents a potential avenue for therapeutic intervention as its inhibition results in the coordinate blockade of multiple oncogenic signaling pathways in cancer cells. Moreover, Hsp90 is essential for the stability and function of numerous client proteins, a number of which have been causally implicated in the pathogenesis of prostate cancer, including the androgen receptor (AR). Here, we examined the preclinical activity of ganetespib, a small molecule inhibitor of Hsp90, in a panel of prostate cancer cell lines. Ganetespib potently decreased viability in all lines, irrespective of their androgen sensitivity or receptor status, and more effectively than the ansamycin inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG). Interestingly, while ganetespib exposure decreased AR expression and activation, the constitutively active V7 truncated isoform of the receptor was unaffected by Hsp90 inhibition. Mechanistically, ganetespib exerted concomitant effects on mitogenic and survival pathways, as well as direct modulation of cell cycle regulators, to induce growth arrest and apoptosis. Further, ganetespib displayed robust antitumor efficacy in both AR-negative and positive xenografts, including those derived from the 22Rv1 prostate cancer cell line that co-expresses full-length and variant receptors. Together these data suggest that further investigation of ganetespib as a new therapeutic treatment for prostate cancer patients is warranted.
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Affiliation(s)
- Suqin He
- Synta Pharmaceuticals Corp., Lexington, MA 02421, USA
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21
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Hartig SM, He B, Newberg JY, Ochsner SA, Loose DS, Lanz RB, McKenna NJ, Buehrer BM, McGuire SE, Marcelli M, Mancini MA. Feed-forward inhibition of androgen receptor activity by glucocorticoid action in human adipocytes. CHEMISTRY & BIOLOGY 2012; 19:1126-41. [PMID: 22999881 PMCID: PMC4259876 DOI: 10.1016/j.chembiol.2012.07.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 07/05/2012] [Accepted: 07/09/2012] [Indexed: 01/03/2023]
Abstract
We compared transcriptomes of terminally differentiated mouse 3T3-L1 and human adipocytes to identify cell-specific differences. Gene expression and high content analysis (HCA) data identified the androgen receptor (AR) as both expressed and functional, exclusively during early human adipocyte differentiation. The AR agonist dihydrotestosterone (DHT) inhibited human adipocyte maturation by downregulation of adipocyte marker genes, but not in 3T3-L1. It is interesting that AR induction corresponded with dexamethasone activation of the glucocorticoid receptor (GR); however, when exposed to the differentiation cocktail required for adipocyte maturation, AR adopted an antagonist conformation and was transcriptionally repressed. To further explore effectors within the cocktail, we applied an image-based support vector machine (SVM) classification scheme to show that adipocyte differentiation components inhibit AR action. The results demonstrate human adipocyte differentiation, via GR activation, upregulates AR but also inhibits AR transcriptional activity.
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Affiliation(s)
- Sean M. Hartig
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Bin He
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Justin Y. Newberg
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Scott A. Ochsner
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - David S. Loose
- Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, USA
| | - Rainer B. Lanz
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Neil J. McKenna
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | | | - Sean E. McGuire
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Marco Marcelli
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
- Michael E. DeBakey VA Medical Center and Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Michael A. Mancini
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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22
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Grosdidier S, Carbó LR, Buzón V, Brooke G, Nguyen P, Baxter JD, Bevan C, Webb P, Estébanez-Perpiñá E, Fernández-Recio J. Allosteric conversation in the androgen receptor ligand-binding domain surfaces. Mol Endocrinol 2012; 26:1078-90. [PMID: 22653923 DOI: 10.1210/me.2011-1281] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Androgen receptor (AR) is a major therapeutic target that plays pivotal roles in prostate cancer (PCa) and androgen insensitivity syndromes. We previously proposed that compounds recruited to ligand-binding domain (LBD) surfaces could regulate AR activity in hormone-refractory PCa and discovered several surface modulators of AR function. Surprisingly, the most effective compounds bound preferentially to a surface of unknown function [binding function 3 (BF-3)] instead of the coactivator-binding site [activation function 2 (AF-2)]. Different BF-3 mutations have been identified in PCa or androgen insensitivity syndrome patients, and they can strongly affect AR activity. Further, comparison of AR x-ray structures with and without bound ligands at BF-3 and AF-2 showed structural coupling between both pockets. Here, we combine experimental evidence and molecular dynamic simulations to investigate whether BF-3 mutations affect AR LBD function and dynamics possibly via allosteric conversation between surface sites. Our data indicate that AF-2 conformation is indeed closely coupled to BF-3 and provide mechanistic proof of their structural interconnection. BF-3 mutations may function as allosteric elicitors, probably shifting the AR LBD conformational ensemble toward conformations that alter AF-2 propensity to reorganize into subpockets that accommodate N-terminal domain and coactivator peptides. The induced conformation may result in either increased or decreased AR activity. Activating BF-3 mutations also favor the formation of another pocket (BF-4) in the vicinity of AF-2 and BF-3, which we also previously identified as a hot spot for a small compound. We discuss the possibility that BF-3 may be a protein-docking site that binds to the N-terminal domain and corepressors. AR surface sites are attractive pharmacological targets to develop allosteric modulators that might be alternative lead compounds for drug design.
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Affiliation(s)
- Solène Grosdidier
- Joint BSC-IRB Research Programme in Computational Biology, Life Sciences Department, Barcelona Supercomputing Center, 08034 Barcelona, Spain
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23
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Shi XB, Xue L, Shi D, deVere White RW. Influence of short polyglutamine tracts and p160 coactivators on the transactivation of the androgen receptor. Cancer Biother Radiopharm 2011; 26:191-201. [PMID: 21539451 DOI: 10.1089/cbr.2010.0888] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The androgen receptor (AR) acting as a transcription factor plays a pivotal role in the occurrence and progression of prostate cancer (CaP). Several AR-related factors or modulators have been reported to influence AR activity. Whether and how these factors cooperatively modulate the AR activity has not been well defined. In the present study, the combined effect of p160 coactivators, short CAG length (encoding a short polyQ tract), and AR mutations on AR transactivation in a yeast system was evaluated. It was found that the short polyQ tract can upregulate the transactivation of the wild-type (WT) AR and partial-function (PF) AR mutants in response to a physiological level (10(-9) M) of dihydrotestosterone. Addition of a p160 coactivator (SRC-1 or TIF2) to the above systems resulted in a significant increase in the ligand-stimulated transactivation. Although the androgen antagonist bicalutamide could suppress the activity of androgen-activated WT or PF ARs, it was unable to do so for gain-of-function AR mutants. A combination of the short polyQ tract and coactivator TIF2 acted cooperatively on the WT AR and PF AR mutants to enhance their transactivation in response to either a low level of dihydrotestosterone (10(-10) M) or adrenal dehydroepiandrosterone. Taken together, this finding suggests that the modulated AR activity may involve early in the carcinogenesis of CaP. Additionally, these data support the concept that a given CaP in which the AR activity is modulated by multiple AR modulators may progress more readily to castrate resistance.
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Affiliation(s)
- Xu-Bao Shi
- Department of Urology, University of California, Davis, School of Medicine, Sacramento, California 95817, USA
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24
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Shiota M, Yokomizo A, Masubuchi D, Tada Y, Inokuchi J, Eto M, Uchiumi T, Fujimoto N, Naito S. Tip60 promotes prostate cancer cell proliferation by translocation of androgen receptor into the nucleus. Prostate 2010; 70:540-54. [PMID: 19938016 DOI: 10.1002/pros.21088] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND There are currently few effective therapies for castration-resistant prostate cancer (CRPCa). CRPC which is resistant to castration is thought to result from increased activation of the androgen/androgen receptor (AR) signaling pathway, which may be augmented by AR coactivators. METHODS Luciferase reporter assay, Western blotting, quantitative real-time polymerase chain reaction, fluorescence microscopy, cell proliferation assay, and flow cytometry for cell-cycle analysis were used to resolve a role of Tip60 regulating AR in PCa cells. RESULTS Tip60 regulated transcriptions of AR target genes androgen independently. Tip60 knockdown induced translocation of AR into the cytoplasm. Acetylation-mimicking mutations in the nuclear localization signal sequence caused AR protein to mainly localize in the nucleus despite androgen starvation, whereas non-acetylation-mimicking mutations caused AR to mainly localize in the cytoplasm despite androgen stimulation. Tip60 overexpression in castration-resistant LNCaP derivative CxR cells resulted in increases in the acetylated form of AR and AR localization in the nucleus even without androgen. Consequently, Tip60 silencing suppressed the growth of AR-expressing PCa cells by inducing cell-cycle arrest at the G1 phase, similar to inhibition of androgen/AR signaling. Furthermore, Tip60 knockdown suppressed the cell growth of CxR cells. CONCLUSIONS Tip60 is involved in the proliferation of PCa cells as an AR coactivator. Modulation of Tip60 expression or function may be a useful strategy for developing novel therapeutics for PCa, even CRPC, which remain dependent on AR signaling, by overexpressing AR and its coactivators.
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Affiliation(s)
- Masaki Shiota
- Department of Urology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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25
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Androgen receptor mutations associated with androgen insensitivity syndrome: a high content analysis approach leading to personalized medicine. PLoS One 2009; 4:e8179. [PMID: 20011049 PMCID: PMC2785468 DOI: 10.1371/journal.pone.0008179] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Accepted: 09/28/2009] [Indexed: 11/19/2022] Open
Abstract
Androgen insensitivity syndrome (AIS) is a rare disease associated with inactivating mutations of AR that disrupt male sexual differentiation, and cause a spectrum of phenotypic abnormalities having as a common denominator loss of reproductive viability. No established treatment exists for these conditions, however there are sporadic reports of patients (or recapitulated mutations in cell lines) that respond to administration of supraphysiologic doses (or pulses) of testosterone or synthetic ligands. Here, we utilize a novel high content analysis (HCA) approach to study AR function at the single cell level in genital skin fibroblasts (GSF). We discuss in detail findings in GSF from three historical patients with AIS, which include identification of novel mechanisms of AR malfunction, and the potential ability to utilize HCA for personalized treatment of patients affected by this condition.
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Bergerat JP, Céraline J. Pleiotropic functional properties of androgen receptor mutants in prostate cancer. Hum Mutat 2009; 30:145-57. [PMID: 18800375 DOI: 10.1002/humu.20848] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The androgen receptor (AR) signaling pathway plays an important role during the development of the normal prostate gland, but also during the progression of prostate cancer on androgen ablation therapy. Mutations in the AR gene emerge to keep active the AR signaling pathway and to support prostate cancer cells growth and survival despite the low levels of circulating androgens. Indeed, mutations affecting the ligand binding domain (LBD) of the AR have been shown to generate so-called "promiscuous" receptors that present widened ligand specificity and allow the stimulation of these receptors by a larger spectrum of endogenous hormones. Another class of mutations, arising in the amino-terminal domain (NTD) of the receptor, modulate AR interactions with coregulators involved in cell proliferation regulation. Besides characteristics of these well-known types of mutations, the properties of other classes of AR mutants recently described in prostate cancer are currently under investigation. Most interestingly, in addition to their potential role in the mechanisms which allow prostate cancer cells to escape androgen ablation therapy, data suggest that certain AR mutations are present early in the natural history of the disease and may play a role in many aspects of prostate cancer progression. Surprisingly, singular truncated AR devoid of their carboxy-terminal end (CTE) region seem to exert specific paracrine effects and to induce a clonal cooperation with neighboring prostate cancer cells, which may facilitate both the invasion and metastasis processes. In this article, we review the functional properties of different classes of AR mutants and their potential impact on the natural history of prostate cancer. Hum Mutat 0, 1-14, 2008. (c) 2008 Wiley-Liss, Inc.
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Affiliation(s)
- Jean-Pierre Bergerat
- EA 3430-Signalisation et Cancer de la Prostate, Faculté de Médecine, Université Strasbourg, Strasbourg, France
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27
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Laurila K, Vihinen M. Prediction of disease-related mutations affecting protein localization. BMC Genomics 2009; 10:122. [PMID: 19309509 PMCID: PMC2680896 DOI: 10.1186/1471-2164-10-122] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 03/23/2009] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Eukaryotic cells contain numerous compartments, which have different protein constituents. Proteins are typically directed to compartments by short peptide sequences that act as targeting signals. Translocation to the proper compartment allows a protein to form the necessary interactions with its partners and take part in biological networks such as signalling and metabolic pathways. If a protein is not transported to the correct intracellular compartment either the reaction performed or information carried by the protein does not reach the proper site, causing either inactivation of central reactions or misregulation of signalling cascades, or the mislocalized active protein has harmful effects by acting in the wrong place. RESULTS Numerous methods have been developed to predict protein subcellular localization with quite high accuracy. We applied bioinformatics methods to investigate the effects of known disease-related mutations on protein targeting and localization by analyzing over 22,000 missense mutations in more than 1,500 proteins with two complementary prediction approaches. Several hundred putative localization affecting mutations were identified and investigated statistically. CONCLUSION Although alterations to localization signals are rare, these effects should be taken into account when analyzing the consequences of disease-related mutations.
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Affiliation(s)
- Kirsti Laurila
- Institute of Medical Technology, FI-33014 University of Tampere, Finland
- Department of Signal Processing, Tampere University of Technology, P.O. Box 527, FI-33101 Tampere, Finland
| | - Mauno Vihinen
- Institute of Medical Technology, FI-33014 University of Tampere, Finland
- Tampere University Hospital, FI-33520 Tampere, Finland
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28
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Pandini G, Genua M, Frasca F, Vigneri R, Belfiore A. Sex Steroids Upregulate the IGF-1R in Prostate Cancer Cells through a Nongenotropic Pathway. Ann N Y Acad Sci 2009; 1155:263-7. [DOI: 10.1111/j.1749-6632.2009.04361.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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29
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Centenera MM, Harris JM, Tilley WD, Butler LM. The contribution of different androgen receptor domains to receptor dimerization and signaling. Mol Endocrinol 2008; 22:2373-82. [PMID: 18617596 DOI: 10.1210/me.2008-0017] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The androgen receptor (AR) is a ligand-activated transcription factor of the nuclear receptor superfamily that plays a critical role in male physiology and pathology. Activated by binding of the native androgens testosterone and 5alpha-dihydrotestosterone, the AR regulates transcription of genes involved in the development and maintenance of male phenotype and male reproductive function as well as other tissues such as bone and muscle. Deregulation of AR signaling can cause a diverse range of clinical conditions, including the X-linked androgen insensitivity syndrome, a form of motor neuron disease known as Kennedy's disease, and male infertility. In addition, there is now compelling evidence that the AR is involved in all stages of prostate tumorigenesis including initiation, progression, and treatment resistance. To better understand the role of AR signaling in the pathogenesis of these conditions, it is important to have a comprehensive understanding of the key determinants of AR structure and function. Binding of androgens to the AR induces receptor dimerization, facilitating DNA binding and the recruitment of cofactors and transcriptional machinery to regulate expression of target genes. Various models of dimerization have been described for the AR, the most well characterized interaction being DNA-binding domain- mediated dimerization, which is essential for the AR to bind DNA and regulate transcription. Additional AR interactions with potential to contribute to receptor dimerization include the intermolecular interaction between the AR amino terminal domain and ligand-binding domain known as the N-terminal/C-terminal interaction, and ligand-binding domain dimerization. In this review, we discuss each form of dimerization utilized by the AR to achieve transcriptional competence and highlight that dimerization through multiple domains is necessary for optimal AR signaling.
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Affiliation(s)
- Margaret M Centenera
- Dame Roma Mitchell Cancer Research Laboratories, Discipline of Medicine, The University of Adelaide and Hanson Institute, PO Box 14, Rundle Mall, Adelaide, South Australia 5000, Australia
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Corry GN, Hendzel MJ, Underhill DA. Subnuclear localization and mobility are key indicators of PAX3 dysfunction in Waardenburg syndrome. Hum Mol Genet 2008; 17:1825-37. [PMID: 18325909 DOI: 10.1093/hmg/ddn076] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Mutations in the transcription factor PAX3 cause Waardenburg syndrome (WS) in humans and the mouse Splotch mutant, which display similar neural crest-derived defects. Previous characterization of disease-causing mutations revealed pleiotropic effects on PAX3 DNA binding and transcriptional activity. In this study, we evaluated the impact of disease alleles on PAX3 localization and mobility. Immunofluorescence analyses indicated that the majority of PAX3 occupies the interchromatin space, with only sporadic colocalization with sites of transcription. Interestingly, PAX3 disease alleles fell into two distinct categories when localization and dynamics in fluorescence recovery after photobleaching (FRAP) were assessed. The first group (class I), comprising N47H, G81A and V265F exhibit a diffuse distribution and markedly increased mobility when compared with wild-type PAX3. In contrast, the G42R, F45L, S84F, Y90H and R271G mutants (class II) display evidence of subnuclear compartmentalization and mobility intermediate between wild-type PAX3 and class I proteins. However, unlike class I mutants, which retain DNA binding, class II proteins are deficient for this activity, indicating that DNA binding is not a primary determinant of PAX3 distribution and movement. Importantly, class I properties prevail when combined with a class II mutation, which taken with the proximity of the two mutant classes within the PAX3 protein, suggests class I mutants act by perturbing PAX3 conformation. Together, these results establish that altered localization and dynamics play a key role in PAX3 dysfunction and that loss of the underlying determinants represents the principal defect for a subset of Waardenburg mutations.
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Affiliation(s)
- Gareth N Corry
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
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31
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Cutress ML, Whitaker HC, Mills IG, Stewart M, Neal DE. Structural basis for the nuclear import of the human androgen receptor. J Cell Sci 2008; 121:957-68. [PMID: 18319300 DOI: 10.1242/jcs.022103] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ligand-dependent nuclear import is crucial for the function of the androgen receptor (AR) in both health and disease. The unliganded AR is retained in the cytoplasm but, on binding 5alpha-dihydrotestosterone, it translocates into the nucleus and alters transcription of its target genes. Nuclear import of AR is mediated by the nuclear import factor importin-alpha, which functions as a receptor that recognises and binds to specific nuclear localisation signal (NLS) motifs on cargo proteins. We show here that the AR binds to importin-alpha directly, albeit more weakly than the NLS of SV40 or nucleoplasmin. We describe the 2.6-angstroms-resolution crystal structure of the importin-alpha-AR-NLS complex, and show that the AR binds to the major NLS-binding site on importin-alpha in a manner different from most other NLSs. Finally, we have shown that pathological mutations within the NLS of AR that are associated with prostate cancer and androgen-insensitivity syndrome reduce the binding affinity to importin-alpha and, subsequently, retard nuclear import; surprisingly, however, the transcriptional activity of these mutants varies widely. Thus, in addition to its function in the nuclear import of AR, the NLS in the hinge region of AR has a separate, quite distinct role on transactivation, which becomes apparent once nuclear import has been achieved.
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Affiliation(s)
- Mark L Cutress
- Uro-Oncology Research Group, Cancer Research UK Cambridge Research Institute, Robinson Way, Cambridge, CB2 0RE, UK
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32
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Redundant enhancement of mouse constitutive androstane receptor transactivation by p160 coactivator family members. Arch Biochem Biophys 2007; 468:49-57. [PMID: 17950690 DOI: 10.1016/j.abb.2007.09.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 08/30/2007] [Accepted: 09/02/2007] [Indexed: 11/23/2022]
Abstract
Constitutive androstane receptor (CAR) transactivation is enhanced by p160 coactivators, which include three members, SRC-1, SRC-2, and SRC-3. Each of the p160 coactivators enhanced mouse CAR (mCAR) transactivation of the CYP2B1 phenobarbital (PB)-responsive enhancer in transfected cultured cells and mouse hepatocytes in vivo. The cellular localization of the p160 coactivators in hepatocytes in vivo was not altered by PB treatment, nor did any of the p160 coactivators selectively colocalize with mCAR in the nucleus. Exogenous expression of each p160 coactivator mediated the PB-independent nuclear accumulation of mCAR in hepatocytes in vivo. Induction of Cyp2b10 gene expression by PB was equivalent or greater in mice null for each of the p160 coactivators than in wild type mice. These results indicate that the p160 coactivators are redundant with regard to enhancing CAR-mediated induction of cytochrome P450 genes. SRC-3 alone of the p160 coactivators enhanced CAR transactivation in hepatic cells without PB treatment.
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Yang CS, Xin HW, Kelley JB, Spencer A, Brautigan DL, Paschal BM. Ligand binding to the androgen receptor induces conformational changes that regulate phosphatase interactions. Mol Cell Biol 2007; 27:3390-404. [PMID: 17325038 PMCID: PMC1899975 DOI: 10.1128/mcb.02411-06] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2006] [Accepted: 02/14/2007] [Indexed: 11/20/2022] Open
Abstract
We describe a mechanism for protein phosphatase 2A (PP2A) targeting to the androgen receptor (AR) and provide insight into the more general issue of kinase and phosphatase interactions with AR. Simian virus 40 (SV40) small t antigen (ST) binding to N-terminal HEAT repeats in the PP2A A subunit induces structural changes transduced to C-terminal HEAT repeats. This enables the C-terminal HEAT repeats in the PP2A A subunit, including HEAT repeat 13, to discriminate between androgen- and androgen antagonist-induced AR conformations. The PP2A-AR interaction was used to show that an AR mutant in prostate cancer cells (T877A) is activated by multiple ligands without acquiring the same conformation as that induced by androgen. The correlation between androgen binding to AR and increased phosphorylation of the activation function 1 (AF-1) region implies that changes in AR conformation or chaperone composition are causal to kinase access to phosphorylation sites. However, AF-1 phosphorylation sites are kinase accessible prior to androgen binding. This suggests that androgens can enhance the phosphorylation state of AR either by negatively regulating the ability of the ligand-binding domain to bind phosphatases or by inducing an AR conformation that is resistant to phosphatase action. SV40 ST subverts this mechanism by promoting the direct transfer of PP2A onto androgen-bound AR, resulting in multisite dephosphorylation.
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Affiliation(s)
- Chun-Song Yang
- Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA
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34
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Pelley RP, Chinnakannu K, Murthy S, Strickland FM, Menon M, Dou QP, Barrack ER, Reddy GPV. Calmodulin-androgen receptor (AR) interaction: calcium-dependent, calpain-mediated breakdown of AR in LNCaP prostate cancer cells. Cancer Res 2007; 66:11754-62. [PMID: 17178871 DOI: 10.1158/0008-5472.can-06-2918] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chemotherapy of prostate cancer targets androgen receptor (AR) by androgen ablation or antiandrogens, but unfortunately, it is not curative. Our attack on prostate cancer envisions the proteolytic elimination of AR, which requires a fuller understanding of AR turnover. We showed previously that calmodulin (CaM) binds to AR with important consequences for AR stability and function. To examine the involvement of Ca(2+)/CaM in the proteolytic breakdown of AR, we analyzed LNCaP cell extracts that bind to a CaM affinity column for the presence of low molecular weight forms of AR (intact AR size, approximately 114 kDa). Using an antibody directed against the NH(2)-terminal domain (ATD) of AR on Western blots, we identified approximately 76-kDa, approximately 50-kDa, and 34/31-kDa polypeptides in eluates of CaM affinity columns, suggesting the presence of CaM-binding sites within the 31/34-kDa ATD of AR. Under cell-free conditions in the presence of phenylmethylsulfonyl fluoride, AR underwent Ca(2+)-dependent degradation. AR degradation was inhibited by N-acetyl-leu-leu-norleu, an inhibitor of thiol proteases, suggesting the involvement of calpain. In intact cells, AR breakdown was accelerated by raising intracellular Ca(2+) using calcimycin, and increased AR breakdown was reversed with the cell-permeable Ca(2+) chelator bis-(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra-(acetoxymethyl)-ester. In CaM affinity chromatography studies, the Ca(2+)-dependent protease calpain was bound to and eluted from the CaM-agarose column along with AR. Caspase-3, which plays a role in AR turnover under stress conditions, did not bind to the CaM column and was present in the proenzyme form. Similarly, AR immunoprecipitates prepared from whole-cell extracts of exponentially growing LNCaP cells contained both calpain and calpastatin. Nuclear levels of calpain and calpastatin (its endogenous inhibitor) changed in a reciprocal fashion as synchronized LNCaP cells progressed from G(1) to S phase. These reciprocal changes correlated with changes in AR level, which increased in late G(1) phase and decreased as S phase progressed. Taken together, these observations suggest potential involvement of AR-bound CaM in calcium-controlled, calpain-mediated breakdown of AR in prostate cancer cells.
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Affiliation(s)
- Ronald P Pelley
- Vattikuti Urology Institute and Department of Dermatology, Henry Ford Hospital, Detroit, MI 48202, USA
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35
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Agoulnik IU, Vaid A, Nakka M, Alvarado M, Bingman WE, Erdem H, Frolov A, Smith CL, Ayala GE, Ittmann MM, Weigel NL. Androgens modulate expression of transcription intermediary factor 2, an androgen receptor coactivator whose expression level correlates with early biochemical recurrence in prostate cancer. Cancer Res 2006; 66:10594-602. [PMID: 17079484 DOI: 10.1158/0008-5472.can-06-1023] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Prostate cancer is an androgen-dependent disease; metastatic prostate cancer is typically treated by androgen receptor (AR) blockade. Recurrence after androgen ablation and evidence that AR continues to play a role in many prostate cancers has led to an examination of other factors that potentiate AR activity. AR is a ligand-activated transcription factor whose activity is regulated not only by hormone but also by the levels of coactivators recruited by AR to facilitate transcription. We sought to assess the consequences of reducing expression of the transcription intermediary factor 2 (TIF2) coactivator on prostate cancer cell growth and AR action in cell lines to examine TIF2 expression in prostate cancer and to correlate expression with clinical outcome. Depletion of TIF2 reduced expression of AR-induced target genes and slowed proliferation of AR-dependent and AR-independent prostate cancer cells. Remarkably, we found that TIF2 expression is directly repressed by high levels of androgens in multiple AR-expressing cell lines. Expression of a reporter containing 5'-flanking region of the TIF2 was repressed both by androgens and by the antagonist, Casodex. Expression of TIF2 correlates with biochemical (prostate-specific antigen) recurrence (P = 0.0136). In agreement with our in vitro findings, the highest expression of TIF2 was found in patients whose cancer relapsed after androgen ablation therapy, supporting the idea that AR blockade might activate pathways that lead to stimulation of AR-dependent and AR-independent proliferation of prostate epithelium. The elevated expression of TIF2 at low hormone levels likely aids in inducing AR activity under these conditions; treatment with Casodex has the potential to counteract this induction.
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Affiliation(s)
- Irina U Agoulnik
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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36
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Marcelli M, Stenoien DL, Szafran AT, Simeoni S, Agoulnik IU, Weigel NL, Moran T, Mikic I, Price JH, Mancini MA. Quantifying effects of ligands on androgen receptor nuclear translocation, intranuclear dynamics, and solubility. J Cell Biochem 2006; 98:770-88. [PMID: 16440331 DOI: 10.1002/jcb.20593] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Using manual and automated high throughput microscopy (HTM), ligand-dependent trafficking of green fluorescent protein-androgen receptor (GFP-AR) was analyzed in fixed and living cells to determine its spatial distribution, solubility, mobility, and co-activator interactions. Within minutes, addition of the agonist R1881 resulted translocation of GFP-AR from the cytoplasm to the nucleus, where it displayed a hyperspeckled pattern and extraction resistance in low expressing cells. AR antagonists (Casodex, hydroxyflutamide) also caused nuclear translocation, however, the antagonist-bound GFP-AR had a more diffuse nuclear distribution, distinct from the agonist-bound GFP-AR, and was completely soluble; overexpressed GFP-AR in treated cells was extraction resistant, independent of ligand type. To more dramatically show the different effects of ligand on AR distribution, we utilized an AR with a mutation in the DNA binding domain (ARC619Y) that forms distinct foci upon exposure to agonists but retains a diffuse nuclear distribution in the presence of antagonists. Live-cell imaging of this mutant demonstrated that cytoplasmic foci formation occurs immediately upon agonist but not antagonist addition. Fluorescence recovery after photobleaching (FRAP) revealed that agonist-bound GFP-AR exhibited reduced mobility relative to unliganded or antagonist-bound GFP-AR. Importantly, agonist-bound GFP-AR mobility was strongly affected by protein expression levels in transiently transfected cells, and displayed reduced mobility even in slightly overexpressing cells. Cyan fluorescent protein-AR (CFP-AR) and yellow fluorescent protein-CREB binding protein (YFP-CBP) in the presence of agonists and antagonists were used to demonstrate that CFP-AR specifically co-localizes with YFP-CBP in an agonist dependent manner. Dual FRAP experiments demonstrated that CBP mobility mirrored AR mobility only in the presence of agonist. HTM enabled simultaneous studies of the sub-cellular distribution of GFP-AR and ARC619Y in response to a range of concentrations of agonists and antagonists (ranging from 10(-12) to 10(-5)) in thousands of cells. These results further support the notion that ligand specific interactions rapidly affect receptor and co-factor organization, solubility, and molecular dynamics, and each can be aberrantly affected by mutation and overexpression.
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Affiliation(s)
- Marco Marcelli
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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37
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Butler LM, Centenera MM, Neufing PJ, Buchanan G, Choong CSY, Ricciardelli C, Saint K, Lee M, Ochnik A, Yang M, Brown MP, Tilley WD. Suppression of Androgen Receptor Signaling in Prostate Cancer Cells by an Inhibitory Receptor Variant. Mol Endocrinol 2006; 20:1009-24. [PMID: 16423882 DOI: 10.1210/me.2004-0401] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
There is increasing evidence that sensitization of the androgen receptor (AR) signaling pathway contributes to the failure of androgen ablation therapy for prostate cancer, and that direct targeting of the AR may be a useful therapeutic approach. To better understand how AR function could be abrogated in prostate cancer cells, we have developed a series of putative dominant-negative variants of the human AR, containing deletions or mutations in activation functions AF-1, AF-5, and/or AF-2. One construct, AR inhibitor (ARi)-410, containing a deletion of AF-1 and part of AF-5 of the AR, had no intrinsic transactivation activity but inhibited wild-type AR (wtAR) in a ligand-dependent manner by at least 95% when transfected at a 4:1 molar ratio. ARi-410 was an equally potent inhibitor of gain-of-function AR variants. Ectopic expression of ARi-410 inhibited the proliferation of AR-positive LNCaP cells, but not AR-negative PC-3 cells. Whereas ARi-410 also marginally inhibited progesterone receptor activity, this was far less pronounced than the effect on AR (50% vs. 95% maximal inhibition, respectively), and there was no inhibition of either vitamin D or estrogen receptor activity. In the presence of ligand, ARi-410 interacted with wtAR, and both receptors translocated into the nucleus. Whereas the amino-carboxy terminal interaction was not necessary for optimal dominant-negative activity, disruption of dimerization through the ligand binding domain reduced the efficacy of ARi-410. In addition, although inhibition of AR function by ARi-410 was not dependent on DNA binding, the DNA binding domain was required for dominant-negative activity. Taken together, our results suggest that interaction between ARi-410 and the endogenous AR in prostate cancer cells, potentially through the DNA binding and ligand binding domains, results in a functionally significant reduction in AR signaling and AR-dependent cell growth.
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Affiliation(s)
- Lisa M Butler
- Dame Roma Mitchell Cancer Research Laboratories, Department of Medicine, The University of Adelaide, Hanson Institute, P.O. Box 14, Rundle Mall, Adelaide, South Australia 5000, Australia.
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38
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Bonamy GM, Allison LA. Oncogenic conversion of the thyroid hormone receptor by altered nuclear transport. NUCLEAR RECEPTOR SIGNALING 2006; 4:e008. [PMID: 16741566 PMCID: PMC1472669 DOI: 10.1621/nrs.04008] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 02/16/2006] [Indexed: 01/14/2023]
Abstract
Nuclear receptors (NRs) are transcription factors whose activity is modulated by ligand binding. These receptors are at the core of complex signaling pathways and act as integrators of many cellular signals. In the last decade our understanding of NRs has greatly evolved. In particular, regulation of NR subcellular dynamics has emerged as central to their activity. Research on the subcellular distribution of the thyroid hormone receptor (TR) has revealed new dimensions in the complexity of NR regulation, and points to the possibility that NR mislocalization plays a key role in oncogenesis. For many years, TR was thought to reside exclusively in the nucleus. It is now known that TR is a dynamic protein that shuttles between the nucleus and cytoplasm. TR is localized to the nucleus in a phosphorylated form, suggesting that compartment-specific phosphorylation mediates cross-talk between multiple cell signaling pathways. The oncoprotein v-ErbA, a viral-derived dominant negative variant of TR is actively exported to the cytoplasm by the CRM1 export receptor. Strikingly, the oncoprotein causes mislocalization of cellular TR and some of its coactivators by direct interaction. Here, we offer some perspectives on the role of subcellular trafficking in the oncogenic conversion of TR, and propose a new model for oncoprotein dominant negative activity.
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39
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Mulholland DJ, Dedhar S, Wu H, Nelson CC. PTEN and GSK3beta: key regulators of progression to androgen-independent prostate cancer. Oncogene 2006; 25:329-37. [PMID: 16421604 DOI: 10.1038/sj.onc.1209020] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Prostate cancer (PrCa) is characterized by progression from an androgen-dependent phenotype to one that is inevitably androgen independent (AI) and lethal. Recent evidence strongly suggests that the phosphatidylinositol-3-kinase/Akt (PI3K/Akt) and androgen receptor (AR) signalling pathways provide prostatic epithelium with the necessary signalling events to escape the apoptotic response associated with androgen withdrawal therapy. Silencing of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and glycogen synthase kinase beta (GSK3beta) are frequently associated with advanced PrCa systems and likely serve critical roles in promoting AR and PI3K/Akt gain-of-function. That PTEN negatively regulates AR and is sufficient to promote metastatic PrCa in murine models strongly implies its role as a gatekeeper of progressive PrCa. In human PrCa, PTEN loss is correlated with substantial increases in Akt(Ser473) and integrin-linked kinase expression, both of which promote Ser(9) phospho-inhibition of GSK3beta and inactivation of apoptotic factors. Sufficient evidence also suggests that GSK3beta is not only a critical regulator of proproliferative signalling but also a promiscuous one as PI3K/Akt pools of GSK3beta are, at least in part, functionally interchangeable with those of the Wnt/beta-catenin pathway. Thus, GSK3beta may serve not only as a mediator of PI3K/Akt activation but may also regulate the potent transactivation and proproliferative effects that Wnt3a and beta-catenin confer upon AR. These data suggest that prostate-specific activation of GSK3beta may serve as a viable pharmacological option. Thus, in this review, we emphasize that temporal changes in GSK3beta and PTEN expression during progression to AI PrCa are important factors when considering the potential for therapies targeting the oncogenic contributions of PI3K/Akt and AR signalling pathways.
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Affiliation(s)
- D J Mulholland
- Department of Molecular and Medical Pharmacology, UCLA School of Medicine, Los Angeles, CA 90095, USA.
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40
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Lin Y, Kokontis J, Tang F, Godfrey B, Liao S, Lin A, Chen Y, Xiang J. Androgen and its receptor promote Bax-mediated apoptosis. Mol Cell Biol 2006; 26:1908-16. [PMID: 16479009 PMCID: PMC1430231 DOI: 10.1128/mcb.26.5.1908-1916.2006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 06/11/2005] [Accepted: 11/11/2005] [Indexed: 01/24/2023] Open
Abstract
Androgen and its receptor (AR) have been reported to have pro- or antiapoptotic functions. However, the underlying molecular mechanism is incompletely understood. We report here that androgen and AR promote Bax-mediated apoptosis in prostate cancer cells. UV irradiation and ectopic expression of Bax induce apoptosis in AR-positive, but not AR-negative prostate cancer cells. UV- and Bax-induced apoptosis is abrogated in AR-positive cells that express small interference RNA (siRNA) of AR and is sensitized by reintroduction of AR into AR-negative cells. Although AR is able to promote Bax-mediated apoptosis independently of androgen, the promotion by AR can be further potentiated by androgen via AR-dependent transcription activation. AR is essential for the translocation of Bax to mitochondria in UV- or Bax-induced apoptosis. Inhibition of Bax expression by Bax siRNA suppresses UV-induced apoptosis in AR-positive cells. In addition, introduction of AR into AR-negative prostate cancer cells upregulates expression levels of the BH3-only protein Noxa, whereas inhibition of Noxa expression reduces the promotion by AR on UV-induced apoptosis. Thus, our results reveal a novel cross talk between the androgen/AR hormonal signaling pathway and the intrinsic apoptotic death pathway that determines the sensitivity of stress-induced apoptosis in prostate cancer cells.
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Affiliation(s)
- Yuting Lin
- Department of Biological, Chemical, and Physical Science, Illinois Institute of Technology, Chicago, IL 60616, USA
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41
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Abstract
Prostate cancer is a significant cause of morbidity and mortality worldwide. Normal prostate tissue is regulated by androgens, which activate the androgen receptor, a nuclear receptor transcription factor. Most prostate tumors retain androgen dependence, therefore, current therapies for advanced prostate cancer either reduce androgen levels or prevent binding to the androgen receptor. Despite this regimen, prostate cancer invariably progresses to a fatal, androgen-refractory state. Although these relapsed tumors are androgen independent, they are still dependent on the androgen receptor for their growth and survival. The focus of this review will be to highlight our current understanding of the mechanisms of androgen receptor activation in androgen-refractory prostate cancer. How these mechanisms of androgen receptor activation could be targeted in this advanced stage of the disease is also discussed.
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Affiliation(s)
- Scott M Dehm
- Mayo Clinic College of Medicine, 200 First Street, SW, Rochester, MN 55905, USA.
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42
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Berno V, Hinojos CA, Amazit L, Szafran AT, Mancini MA. High-resolution, high-throughput microscopy analyses of nuclear receptor and coregulator function. Methods Enzymol 2006; 414:188-210. [PMID: 17110193 DOI: 10.1016/s0076-6879(06)14011-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
Abstract
Steroid nuclear receptors are ligand-dependent transcription factors that have been studied since the early 1960s by principally biochemical and reporter assay approaches. From these studies an elegant and complex model of nuclear receptor transcription regulation has been developed. Inherent to both biochemical and reporter assay approaches is the generation of averaged responses and it is not generally considered that individual cells could exhibit quite varied responses. In some cases, recent microscopic single-cell analyses provide markedly different responses relative to traditional approaches based on population averaging and underscore the need to continue refinement of the current model of nuclear receptor-regulated transcription. While single-cell analyses of nuclear receptor action have been hindered by the predominantly qualitative nature of the approach, high-throughput microscopy is now available to resolve this issue. This chapter demonstrates the utility of high-throughput microscopic analyses of nuclear receptor and nuclear receptor coregulator function. The ability of high-throughput microscopy to generate physiologically appropriate test populations by filtering based on morphological and protein of interest expression criteria is demonstrated. High-resolution, high-throughput microscopy is illustrated that provides quantitative subcellular information for both androgen and estrogen receptors. Efforts are ongoing to develop model systems that provide additional multiplex data and with refined image analyses to achieve true high-content imaging screens.
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Affiliation(s)
- Valeria Berno
- Integrated Microscopy Core, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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43
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Corry GN, Underhill DA. Subnuclear compartmentalization of sequence-specific transcription factors and regulation of eukaryotic gene expression. Biochem Cell Biol 2005; 83:535-47. [PMID: 16094457 DOI: 10.1139/o05-062] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
To date, the majority of the research regarding eukaryotic transcription factors has focused on characterizing their function primarily through in vitro methods. These studies have revealed that transcription factors are essentially modular structures, containing separate regions that participate in such activities as DNA binding, protein-protein interaction, and transcriptional activation or repression. To fully comprehend the behavior of a given transcription factor, however, these domains must be analyzed in the context of the entire protein, and in certain cases the context of a multiprotein complex. Furthermore, it must be appreciated that transcription factors function in the nucleus, where they must contend with a variety of factors, including the nuclear architecture, chromatin domains, chromosome territories, and cell-cycle-associated processes. Recent examinations of transcription factors in the nucleus have clarified the behavior of these proteins in vivo and have increased our understanding of how gene expression is regulated in eukaryotes. Here, we review the current knowledge regarding sequence-specific transcription factor compartmentalization within the nucleus and discuss its impact on the regulation of such processes as activation or repression of gene expression and interaction with coregulatory factors.
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Affiliation(s)
- Gareth N Corry
- Department of Medical Genetics, University of Alberta, Edmonton, Canada
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44
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Agoulnik IU, Vaid A, Bingman WE, Erdeme H, Frolov A, Smith CL, Ayala G, Ittmann MM, Weigel NL. Role of SRC-1 in the promotion of prostate cancer cell growth and tumor progression. Cancer Res 2005; 65:7959-67. [PMID: 16140968 DOI: 10.1158/0008-5472.can-04-3541] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Prostate cancer is initially androgen dependent and there is evidence that androgen receptor continues to play a role in androgen-independent prostate cancer. Androgen receptor activity depends both on the level of androgens and on the level of coactivators that interact with androgen receptor. Our goal was to evaluate the role of the androgen receptor coactivator SRC-1 in prostate cancer progression. Using tissue arrays to measure SRC-1 protein levels, we found that increased SRC-1 expression in clinically localized, androgen-dependent cancer is associated with clinical and pathologic variables of increased tumor aggressiveness. Interestingly, there was variable expression of SRC-1 in normal prostate tissue which correlated with the staining intensity of the corresponding cancer tissue. To test the contribution of SRC-1, we examined its role in androgen-dependent LNCaP and androgen-independent C4-2 prostate cancer cell lines. Using small interfering RNA to reduce expression of androgen receptor, we found that androgen receptor was required both for cell growth and for basal expression of prostate-specific antigen in the androgen-independent C4-2 cell line. Thus, although the cells can grow in an androgen-depleted medium, they remained androgen receptor dependent. Reduction of SRC-1 expression significantly reduced growth and altered androgen receptor target gene regulation in both LNCaP and C4-2 cell lines whereas it had no effect on the growth of the androgen receptor-negative PC-3 and DU145 prostate cancer cell lines. Although the requirement for androgens and androgen receptor in the development of prostate cancer is well established, our study implicates enhanced androgen receptor activity through elevated expression of SRC-1 in the development of more aggressive disease in men with prostate cancer.
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Affiliation(s)
- Irina U Agoulnik
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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45
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Kawate H, Wu Y, Ohnaka K, Tao RH, Nakamura KI, Okabe T, Yanase T, Nawata H, Takayanagi R. Impaired nuclear translocation, nuclear matrix targeting, and intranuclear mobility of mutant androgen receptors carrying amino acid substitutions in the deoxyribonucleic acid-binding domain derived from androgen insensitivity syndrome patients. J Clin Endocrinol Metab 2005; 90:6162-9. [PMID: 16118342 DOI: 10.1210/jc.2005-0179] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Recent imaging studies revealed that androgen receptor (AR) is ligand-dependently translocated from the cytoplasm into the nucleus and forms intranuclear fine foci. In this study, we examined whether intracellular dynamics of mutant ARs detected in two androgen insensitivity syndrome (AIS) patients was impaired. OBJECTIVE ARs with mutations in the DNA-binding domain were functionally characterized and compared with the wild-type AR. PATIENTS In a complete AIS patient (subject 1), cysteine residue 579 in the first zinc finger motif of AR was substituted for phenylalanine (AR-C579F). Another mutation (AR-F582Y) was found in a partial AIS patient (subject 2). RESULTS AR-F582Y retained less than 10% of the transactivation activity of the wild-type AR, whereas no ligand-dependent transactivation was detected for AR-C579F. Image analyses of the receptors fused to green fluorescent protein showed that the wild-type AR was ligand-dependently translocated into the nucleus in which it formed fine subnuclear foci. Surprisingly, after the addition of dihydrotestosterone, the two mutant ARs initially formed large cytoplasmic dots, many of which were found to be close to mitochondria by electron microscopy. Subsequently, a part of the ligand-bound mutant ARs gradually entered the nucleus to form a smaller number of larger dots, compared with the wild-type AR. Fluorescence recovery after photobleaching analysis revealed that the intranuclear mobility of the mutant ARs decreased, compared with that of the wild-type AR. CONCLUSIONS These results suggest that the abnormal translocation, localization, and mobility of the mutant ARs may be the cause of AIS in these subjects.
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Affiliation(s)
- Hisaya Kawate
- Department of Geriatric Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Bonamy GMC, Guiochon-Mantel A, Allison LA. Cancer promoted by the oncoprotein v-ErbA may be due to subcellular mislocalization of nuclear receptors. Mol Endocrinol 2005; 19:1213-30. [PMID: 15650025 DOI: 10.1210/me.2004-0204] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The retroviral v-ErbA oncoprotein is a highly mutated variant of the thyroid hormone receptor alpha (TRalpha), which is unable to bind T(3) and interferes with the action of TRalpha in mammalian and avian cancer cells. v-ErbA dominant-negative activity is attributed to competition with TRalpha for T(3)-responsive DNA elements and/or auxiliary factors involved in the transcriptional regulation of T(3)-responsive genes. However, competition models do not address the altered subcellular localization of v-ErbA and its possible implications in oncogenesis. Here, we report that v-ErbA dimerizes with TRalpha and the retinoid X receptor and sequesters a significant fraction of the two nuclear receptors in the cytoplasm. Recruitment of TRalpha to the cytoplasm by v-ErbA can be partially reversed in the presence of ligand and when chromatin is disrupted by the histone deacetylase inhibitor trichostatin A. These results define a new mode of action of v-ErbA and illustrate the importance of cellular compartmentalization in transcriptional regulation and oncogenesis.
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Affiliation(s)
- Ghislain M C Bonamy
- Department of Biology, College of William and Mary, P.O. Box 8795, Millington Hall 116, Williamsburg, VA 23187-8795, USA
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Pandini G, Mineo R, Frasca F, Roberts CT, Marcelli M, Vigneri R, Belfiore A. Androgens Up-regulate the Insulin-like Growth Factor-I Receptor in Prostate Cancer Cells. Cancer Res 2005; 65:1849-57. [PMID: 15753383 DOI: 10.1158/0008-5472.can-04-1837] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this study, we show that androgens up-regulate insulin-like growth factor-I receptor (IGF-IR) expression and sensitize prostate cancer cells to the biological effects of IGF-I. Both dihydrotestosterone and the synthetic androgen R1881 induced an approximately 6-fold increase in IGF-IR expression in androgen receptor (AR)-positive prostate cancer cells LNCaP. In accordance with IGF-IR up-regulation, treatment with the nonmetabolizable androgen R1881 sensitized LNCaP cells to the mitogenic and motogenic effects of IGF-I, whereas an IGF-IR blocking antibody effectively inhibited these effects. By contrast, these androgens did not affect IGF-IR expression in AR-negative prostate cancer cells PC-3. Reintroduction of AR into PC-3 cells by stable transfection restored the androgen effect on IGF-IR up-regulation. R1881-induced IGF-IR up-regulation was partially inhibited by the AR antagonist Casodex (bicalutamide). Two other AR antagonists, cyproterone acetate and OH-flutamide, were much less effective. Androgen-induced IGF-IR up-regulation was not dependent on AR genomic activity, because two AR mutants, AR-C619Y and AR-C574R, devoid of DNA binding activity and transcriptional activity were still able to elicit IGF-IR up-regulation in HEK293 kidney cells in response to androgens. Moreover, androgen-induced IGF-IR up-regulation involves the activation of the Src-extracellular signal-regulated kinase pathway, because it was inhibited by both the Src inhibitor PP2 and the MEK-1 inhibitor PD98059. The present observations strongly suggest that AR activation may stimulate prostate cancer progression through the altered IGF-IR expression and IGF action. Anti-androgen therapy may be only partially effective, or almost ineffective, in blocking important biological effects of androgens, such as activation of the IGF system.
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Affiliation(s)
- Giuseppe Pandini
- Dipartimento di Medicina Interna e di Medicina Specialistica, Cattedra di Endocrinologia, University of Catania, Ospedale Garibaldi, Catania, Italy
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Yang CS, Vitto MJ, Busby SA, Garcia BA, Kesler CT, Gioeli D, Shabanowitz J, Hunt DF, Rundell K, Brautigan DL, Paschal BM. Simian virus 40 small t antigen mediates conformation-dependent transfer of protein phosphatase 2A onto the androgen receptor. Mol Cell Biol 2005; 25:1298-308. [PMID: 15684382 PMCID: PMC548022 DOI: 10.1128/mcb.25.4.1298-1308.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Revised: 10/27/2004] [Accepted: 11/11/2004] [Indexed: 01/21/2023] Open
Abstract
The tumor antigens simian virus 40 small t antigen (ST) and polyomavirus small and medium T antigens mediate cell transformation in part by binding to the structural A subunit of protein phosphatase 2A (PP2A). The replacement of B subunits by tumor antigens inhibits PP2A activity and prolongs phosphorylation-dependent signaling. Here we show that ST mediates PP2A A/C heterodimer transfer onto the ligand-activated androgen receptor (AR). Transfer by ST is strictly dependent on the agonist-activated conformation of AR, occurs within minutes of the addition of androgen to cells, and can occur in either the cytoplasm or the nucleus. The binding of ST changes the conformation of the A subunit, and ST rapidly dissociates from the complex upon PP2A A/C heterodimer binding to AR. PP2A is transferred onto the carboxyl-terminal half of AR, and the phosphatase activity is directed to five phosphoserines in the amino-terminal activation function region 1, with a corresponding reduction in transactivation. Thus, ST functions as a transfer factor to specify PP2A targeting in the cell and modulates the transcriptional activity of AR.
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Affiliation(s)
- Chun-Song Yang
- Center for Cell Signaling, University of Virginia, Box 800577 Health Systems, Charlottesville, VA 22908, USA
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Agoulnik IU, Tong XW, Fischer DC, Körner K, Atkinson NE, Edwards DP, Headon DR, Weigel NL, Kieback DG. A germline variation in the progesterone receptor gene increases transcriptional activity and may modify ovarian cancer risk. J Clin Endocrinol Metab 2004; 89:6340-7. [PMID: 15579801 DOI: 10.1210/jc.2004-0114] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Recently, we and others have detected a haplotype of the human progesterone receptor gene (PR). This haplotype consists of a 320-bp insertion in intron G together with point mutations in exons 4 and 5 and was named PROGINS. Whereas the exon 5 mutation is silent, the mutation in exon 4 results in a V660L substitution. Interestingly, this genetic polymorphism was seen to cosegregate with an increased risk of sporadic ovarian cancer in different ethnic groups. Our data provide evidence for the existence of an epidemiological link between a mutated progesterone receptor allele and ovarian cancer (odds ratio, 3.02; 95% confidence interval, 1.86-4.91). Functional characterization of the mutated receptor protein revealed a greater transcriptional activity compared with the wild-type receptor. By contrast, hormone binding and hormone dissociation rates were similar in both receptor proteins. We found that the increased transcriptional activity was due to increased stability resulting in higher expression of the mutant protein. Thus, the long-lasting hyperactivation of progesterone receptor-driven genes secondary to the increased transcriptional activity of the mutated progesterone receptor may participate in ovarian carcinogenesis. This is of special interest, because only a few genetic markers are available for the majority of women diagnosed with sporadic ovarian cancer.
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Affiliation(s)
- Irina U Agoulnik
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Hoang T, Fenne IS, Cook C, Børud B, Bakke M, Lien EA, Mellgren G. cAMP-dependent protein kinase regulates ubiquitin-proteasome-mediated degradation and subcellular localization of the nuclear receptor coactivator GRIP1. J Biol Chem 2004; 279:49120-30. [PMID: 15347661 DOI: 10.1074/jbc.m409746200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Nuclear receptors and their coactivators are key regulators of numerous physiological functions. GRIP1 (glucocorticoid receptor-interacting protein) is a member of the steroid receptor coactivator family. Here, we show that GRIP1 is regulated by cAMP-dependent protein kinase (PKA) that induces its degradation through the ubiquitin-proteasome pathway. GRIP1 was down-regulated in transiently transfected COS-1 cells after treatment with 8-para-chlorophenylthio-cAMP or forskolin and 3-isobutyl-1-methylxanthine and in adrenocortical Y1 cells after incubation with adrenocorticotropic hormone. Pulse-chase experiments with transiently transfected COS-1 cells demonstrated that the half-life of GRIP1 was markedly reduced in cells overexpressing the PKA catalytic subunit, suggesting that activation of PKA increases the turnover of GRIP1 protein. The proteasome inhibitors MG132 and lactacystin abolished the PKA-mediated degradation of GRIP1. Using ts20 cells, a temperature-sensitive cell line that contains a thermolabile ubiquitin-activating E1 enzyme, it was confirmed that PKA-mediated degradation of GRIP1 is dependent upon the ubiquitin-proteasome pathway. Coimmunoprecipitation studies of COS-1 cells transfected with expression vectors encoding GRIP1 and ubiquitin using anti-GRIP1 and anti-ubiquitin antibodies showed that the ubiquitination of GRIP1 was increased by overexpression of PKA. Finally, we show that PKA regulates the intracellular distribution pattern of green fluorescent protein-GRIP1 and stimulates recruitment of GRIP1 to subnuclear foci that are colocalized with the proteasome. Taken together, these data demonstrate that GRIP1 is ubiquitinated and degraded through activation of the PKA pathway. This may represent a novel regulatory mechanism whereby hormones down-regulate a nuclear receptor coactivator.
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Affiliation(s)
- Tuyen Hoang
- Hormone Laboratory, Section of Endocrinology, Institute of Medicine, Division of Anatomy and Cell Biology, Department of Biomedicine, University of Bergen and Haukeland University Hospital, Bergen N-5021, Norway
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