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Mehralivand S, Thomas C, Puhr M, Claessens F, van de Merbel AF, Dubrovska A, Jenster G, Bernemann C, Sommer U, Erb HHH. New advances of the androgen receptor in prostate cancer: report from the 1st International Androgen Receptor Symposium. J Transl Med 2024; 22:71. [PMID: 38238739 PMCID: PMC10795409 DOI: 10.1186/s12967-024-04878-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/10/2024] [Indexed: 01/22/2024] Open
Abstract
The androgen receptor (AR) is a crucial player in various aspects of male reproduction and has been associated with the development and progression of prostate cancer (PCa). Therefore, the protein is the linchpin of current PCa therapies. Despite great research efforts, the AR signaling pathway has still not been deciphered, and the emergence of resistance is still the biggest problem in PCa treatment. To discuss the latest developments in AR research, the "1st International Androgen Receptor Symposium" offered a forum for the exchange of clinical and scientific innovations around the role of the AR in prostate cancer (PCa) and to stimulate new collaborative interactions among leading scientists from basic, translational, and clinical research. The symposium included three sessions covering preclinical studies, prognostic and diagnostic biomarkers, and ongoing prostate cancer clinical trials. In addition, a panel discussion about the future direction of androgen deprivation therapy and anti-AR therapy in PCa was conducted. Therefore, the newest insights and developments in therapeutic strategies and biomarkers are discussed in this report.
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Affiliation(s)
- Sherif Mehralivand
- Department of Urology, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307, Dresden, Germany
| | - Christian Thomas
- Department of Urology, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307, Dresden, Germany
| | - Martin Puhr
- Department of Urology, Medical University of Innsbruck, Innsbruck, Austria
| | - Frank Claessens
- Molecular Endocrinology Laboratory, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | | | - Anna Dubrovska
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden and Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
- Institute of Radiooncology-OncoRay, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
- National Center for Tumor Diseases (NCT), Dresden, Germany
- German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Guido Jenster
- Department of Urology, Erasmus MC Cancer Institute, University Medical Center, Rotterdam, The Netherlands
| | | | - Ulrich Sommer
- Institut für Pathologie, Medical Faculty, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Holger H H Erb
- Department of Urology, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstraße 74, 01307, Dresden, Germany.
- German Cancer Consortium (DKTK), Partner Site Dresden and German Cancer Research Center (DKFZ), Heidelberg, Germany.
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Toocheck C, Clister T, Shupe J, Crum C, Ravindranathan P, Lee TK, Ahn JM, Raj GV, Sukhwani M, Orwig KE, Walker WH. Mouse Spermatogenesis Requires Classical and Nonclassical Testosterone Signaling. Biol Reprod 2015; 94:11. [PMID: 26607719 PMCID: PMC4809556 DOI: 10.1095/biolreprod.115.132068] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 11/16/2015] [Indexed: 01/12/2023] Open
Abstract
Testosterone acts though the androgen receptor in Sertoli cells to support germ cell development (spermatogenesis) and male fertility, but the molecular and cellular mechanisms by which testosterone acts are not well understood. Previously, we found that in addition to acting through androgen receptor to directly regulate gene expression (classical testosterone signaling pathway), testosterone acts through a nonclassical pathway via the androgen receptor to rapidly activate kinases that are known to regulate spermatogenesis. In this study, we provide the first evidence that nonclassical testosterone signaling occurs in vivo as the MAP kinase cascade is rapidly activated in Sertoli cells within the testis by increasing testosterone levels in the rat. We find that either classical or nonclassical signaling regulates testosterone-mediated Rhox5 gene expression in Sertoli cells within testis explants. The selective activation of classical or nonclassical signaling pathways in Sertoli cells within testis explants also resulted in the differential activation of the Zbtb16 and c-Kit genes in adjacent spermatogonia germ cells. Delivery of an inhibitor of either pathway to Sertoli cells of mouse testes disrupted the blood-testis barrier that is essential for spermatogenesis. Furthermore, an inhibitor of nonclassical testosterone signaling blocked meiosis in pubertal mice and caused the loss of meiotic and postmeiotic germ cells in adult mouse testes. An inhibitor of the classical pathway caused the premature release of immature germ cells. Collectively, these observations indicate that classical and nonclassical testosterone signaling regulate overlapping and distinct functions that are required for the maintenance of spermatogenesis and male fertility.
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Affiliation(s)
- Corey Toocheck
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Terri Clister
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - John Shupe
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Chelsea Crum
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Preethi Ravindranathan
- Department of Urology, University of Texas, Southwestern Medical Center at Dallas, Dallas, Texas
| | - Tae-Kyung Lee
- Department of Chemistry, University of Texas, Dallas, Richardson, Texas
| | - Jung-Mo Ahn
- Department of Chemistry, University of Texas, Dallas, Richardson, Texas
| | - Ganesh V Raj
- Department of Urology, University of Texas, Southwestern Medical Center at Dallas, Dallas, Texas
| | - Meena Sukhwani
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kyle E Orwig
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - William H Walker
- Center for Research in Reproductive Physiology, Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
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Narizhneva NV, Tararova ND, Ryabokon P, Shyshynova I, Prokvolit A, Komarov PG, Purmal AA, Gudkov AV, Gurova KV. Small molecule screening reveals a transcription-independent pro-survival function of androgen receptor in castration-resistant prostate cancer. Cell Cycle 2009; 8:4155-67. [PMID: 19946220 DOI: 10.4161/cc.8.24.10316] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In prostate cancer (PCa) patients, initial responsiveness to androgen deprivation therapy is frequently followed by relapse due to development of treatment-resistant androgen-independent PCa. This is typically associated with acquisition of mutations in AR that allow activity as a transcription factor in the absence of ligand, indicating that androgen-independent PCa remains dependent on AR function. Our strategy to effectively target AR in androgen-independent PCa involved using a cell-based readout to isolate small molecules that inhibit AR transactivation function through mechanisms other than modulation of ligand binding. A number of the identified inhibitors were toxic to AR-expressing PCa cells regardless of their androgen dependence. Among these, some only suppressed PCa cell growth (ARTIS), while others induced cell death (ARTIK). ARTIK, but not ARTIS, compounds caused disappearance of AR protein from treated cells. siRNA against AR behaved like ARTIK compounds, while a dominant negative AR mutant that prevents AR-mediated transactivation but does not eliminate the protein showed only a growth suppressive effect. These observations reveal a transcription-independent function of AR that is essential for PCa cell viability and, therefore, is an ideal target for anti-PCa treatment. Indeed, several of the identified AR inhibitors demonstrated in vivo efficacy in mouse models of PCa and are candidates for pharmacologic optimization.
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Wang SH, Yeh SH, Lin WH, Wang HY, Chen DS, Chen PJ. Identification of androgen response elements in the enhancer I of hepatitis B virus: a mechanism for sex disparity in chronic hepatitis B. Hepatology 2009; 50:1392-402. [PMID: 19670412 DOI: 10.1002/hep.23163] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
UNLABELLED Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) occurs more often in men than in women. Male HBV carriers usually have higher viral loads, which is a well-known risk factor for HCC. Whether and how the male androgen axis regulates HBV transcription and replication is investigated here. We used HBV transgenic mice to evaluate any sex disparity of serum hepatitis B surface antigen and HBV titers as well as the castration effect on this disparity. Compared to females, HBV transgenic male mice showed higher hepatitis B surface antigen and viral titers, which were lessened by castration of the males. In a cell culture system, HepG2 cells transfected with HBV and androgen receptor (AR) constructs were used to study the effect of the androgen pathway on viral transcription and replication. We found the ligand-stimulated AR could increase the transcription of HBV RNAs through its transcription activation domain. A genomic region within HBV enhancer I was identified that is responsible for the transcriptional activation of AR. The results from chromatin immunoprecipitation and in vitro binding assays further demonstrated a direct binding of AR to this region, in a ligand-dependent manner. Two androgen-responsive element motifs in this region were identified, and their mutations can significantly abolish the AR effects. CONCLUSION This study demonstrated that the androgen pathway can increase the transcription of HBV through direct binding to the androgen-responsive element sites in viral enhancer I. This may explain a higher HBV titer in male carriers and an increased risk of HCC.
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Affiliation(s)
- Sheng-Han Wang
- Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan
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Copland JA, Sheffield-Moore M, Koldzic-Zivanovic N, Gentry S, Lamprou G, Tzortzatou-Stathopoulou F, Zoumpourlis V, Urban RJ, Vlahopoulos SA. Sex steroid receptors in skeletal differentiation and epithelial neoplasia: is tissue-specific intervention possible? Bioessays 2009; 31:629-41. [DOI: 10.1002/bies.200800138] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Eder IE, Haag P, Bartsch G, Klocker H. Targeting the androgen receptor in hormone-refractory prostate cancer--new concepts. Future Oncol 2006; 1:93-101. [PMID: 16555979 DOI: 10.1517/14796694.1.1.91] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The androgen receptor (AR) plays a key regulatory role in hormone-naive, as well as in advanced, therapy-resistant prostate cancer. Therefore, the development of novel treatment strategies using new means for targeting AR function in prostate tumors aims at providing better options for control of progression and progressive disease. This review summarizes recent attempts in this field with a critical view on their clinical usefulness. In addition to classic endocrine therapy by surgical and/or chemical castration, there are concepts to inhibit the AR directly through anti-androgens, selective AR modulators, naturally occurring AR inhibitors, neutralizing antibodies and dominant-negative peptides. A unique possibility to prevent AR expression at the transcriptional level represents the use of antisense technology. The advantage of this method is that AR expression, and thus any aberrant route of its activation is prevented. Furthermore, there are several approaches by which AR signaling is inactivated indirectly. Degradation of heat-shock proteins, which direct appropriate AR protein folding, or modulation of various growth factor signaling cascades, which are thought to contribute to AR activation in the androgen-deprived patient, have been investigated.
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Affiliation(s)
- Iris E Eder
- Department of Urology, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria
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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: 0.8] [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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Scher HI, Sawyers CL. Biology of progressive, castration-resistant prostate cancer: directed therapies targeting the androgen-receptor signaling axis. J Clin Oncol 2005; 23:8253-61. [PMID: 16278481 DOI: 10.1200/jco.2005.03.4777] [Citation(s) in RCA: 796] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prostate cancers that are progressing on medical and surgical therapies designed to ablate the action of androgens continue to express androgen receptor (AR) and to depend on signaling through the receptor for growth. A more clinically relevant classification of castration-resistant disease focuses on the mechanisms of receptor activation, which include (1) changes in the level of ligand(s) in tumor tissue; (2) increased levels of the protein due to gene amplification or altered mRNA expression; (3) activating mutations in the receptor that affect structure and function; (4) changes in coregulatory molecules including coactivators and corepressors; and (5) factors that lead to activation of the receptor independent of the level of ligand or receptor allowing kinase cross talk. From an AR perspective, the term "hormone refractory" is inappropriate. On the basis of this schema, we discuss strategies that are focused on the AR either directly or indirectly, as single agents or in combination, that are in clinical development.
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Affiliation(s)
- Howard I Scher
- Genitourinary Oncology Service, Department of Medicine, Sidney Kimmel Center for Prostate and Urologic Cancers, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10021, USA.
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Oliva J, El Messaoudi S, Pellestor F, Fuentes M, Georget V, Balaguer P, Cavaillès V, Vignon F, Badia E. Involvement of HP1alpha protein in irreversible transcriptional inactivation by antiestrogens in breast cancer cells. FEBS Lett 2005; 579:4278-86. [PMID: 16051232 DOI: 10.1016/j.febslet.2005.06.060] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 06/23/2005] [Accepted: 06/27/2005] [Indexed: 12/28/2022]
Abstract
Resistance to 4-hydroxy-tamoxifen (OHT), which appears in breast cancer cells after long-term antiestrogen treatment, may involve irreversible changes of gene expression. We previously developed a MCF-7 derived cell line (MVLN), in which OHT rapidly and irreversibly inactivates the expression of an estrogen-regulated luciferase transgene (Vit-tk-luciferase). In chromatin immunoprecipitation experiments, heterochromatin protein 1 (HP1alpha) was found to be associated with the Vit-tk-luciferase transgene, only when it was inactivated by OHT treatment. Chimeras composed of either HP1alpha or the Krupple-associated box (KRAB) module of KOX-1 protein (known to repress gene expression by recruitment of HP1 proteins), fused to the estrogen receptor (ER)-DNA binding domain (DBD) and the androgen receptor (AR)-ligand binding domain (LBD) were generated and appeared as potent transcriptional repressors. In stably transfected MVLN cells, irreversible inactivation of the luciferase transgene expression obtained with HP1alpha-ER(DBD)-AR(LBD) was partial, whereas inactivation obtained with KRAB-ER(DBD)-AR(LBD) was comparable to that obtained with OHT, although with a slower kinetics. Altogether, these data suggest that HP1alpha is involved in the silencing effects associated with long-term OHT treatments.
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MESH Headings
- Breast Neoplasms/genetics
- Breast Neoplasms/immunology
- Breast Neoplasms/metabolism
- Chromatin Immunoprecipitation
- Chromobox Protein Homolog 5
- Chromosomal Proteins, Non-Histone/metabolism
- DNA-Binding Proteins/analysis
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Drug Resistance, Neoplasm/genetics
- Estrogen Antagonists/pharmacology
- Gene Silencing
- Humans
- Kruppel-Like Transcription Factors
- Luciferases/analysis
- Luciferases/genetics
- Protein Isoforms/metabolism
- Receptors, Androgen/analysis
- Receptors, Androgen/genetics
- Receptors, Androgen/metabolism
- Receptors, Estrogen/analysis
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Recombinant Fusion Proteins/analysis
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Repressor Proteins/analysis
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Tamoxifen/analogs & derivatives
- Tamoxifen/pharmacology
- Transcription, Genetic/drug effects
- Transgenes
- Tumor Cells, Cultured
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Affiliation(s)
- Joan Oliva
- Institut National de la Santé et de la Recherche Médicale U540, Endocrinologie Moléculaire et Cellulaire des Cancers and Université de Montpellier I, 60 rue de Navacelles, 34090 Montpellier, France
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Pike J, Holmes D, Kamalati T, Davies D, Tolhurst R, Mazhar D, Fishpool S, al-Jehani R, Waxman J, Zelent A, Lemoine NR, Ali S, Buluwela L. Silencing of androgen-regulated genes using a fusion of AR with the PLZF transcriptional repressor. Oncogene 2004; 23:7561-70. [PMID: 15334066 DOI: 10.1038/sj.onc.1208030] [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: 11/08/2022]
Abstract
The androgen receptor (AR) is a member of the nuclear receptor superfamily of ligand-activated transcription factors and plays a key role in the development and progression of prostate cancer. Current therapies include the use of antiandrogens aimed at inhibiting the transcriptional activation of AR-regulated genes by AR. Here, we explore a strategy aimed at obtaining silencing of AR-regulated genes, based on the properties of the transcriptional repressor promyelocytic leukamia zinc-finger protein (PLZF). In order to do this, we have made a fusion protein between PLZF and AR, named PLZF-AR, and show that PLZF-AR is able to bring about silencing of genomically encoded AR-regulated genes and inhibit the androgen-regulated growth of LNCaP prostate cancer cells. Together, our results show that this strategy is able to bring about potent repression of AR-regulated responses and, therefore, could be of value in the development of new therapies for prostate cancer.
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Affiliation(s)
- Joanna Pike
- Department of Cancer Medicine, Imperial College London, Du Cane Road, W12 0NN, UK
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