101
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Chan SC, Selth LA, Li Y, Nyquist MD, Miao L, Bradner JE, Raj GV, Tilley WD, Dehm SM. Targeting chromatin binding regulation of constitutively active AR variants to overcome prostate cancer resistance to endocrine-based therapies. Nucleic Acids Res 2015; 43:5880-97. [PMID: 25908785 PMCID: PMC4499120 DOI: 10.1093/nar/gkv262] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/16/2015] [Indexed: 11/29/2022] Open
Abstract
Androgen receptor (AR) variants (AR-Vs) expressed in prostate cancer (PCa) lack the AR ligand binding domain (LBD) and function as constitutively active transcription factors. AR-V expression in patient tissues or circulating tumor cells is associated with resistance to AR-targeting endocrine therapies and poor outcomes. Here, we investigated the mechanisms governing chromatin binding of AR-Vs with the goal of identifying therapeutic vulnerabilities. By chromatin immunoprecipitation and sequencing (ChIP-seq) and complementary biochemical experiments, we show that AR-Vs display a binding preference for the same canonical high-affinity androgen response elements (AREs) that are preferentially engaged by AR, albeit with lower affinity. Dimerization was an absolute requirement for constitutive AR-V DNA binding and transcriptional activation. Treatment with the bromodomain and extraterminal (BET) inhibitor JQ1 resulted in inhibition of AR-V chromatin binding and impaired AR-V driven PCa cell growth in vitro and in vivo. Importantly, this was associated with a novel JQ1 action of down-regulating AR-V transcript and protein expression. Overall, this study demonstrates that AR-Vs broadly restore AR chromatin binding events that are otherwise suppressed during endocrine therapy, and provides pre-clinical rationale for BET inhibition as a strategy for inhibiting expression and chromatin binding of AR-Vs in PCa.
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Affiliation(s)
- Siu Chiu Chan
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55905, USA
| | - Luke A Selth
- Dame Roma Mitchell Cancer Research Laboratories and Freemasons Foundation Centre for Mens' Health, School of Medicine, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Yingming Li
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55905, USA
| | - Michael D Nyquist
- Graduate Program in Molecular, Cellular, Developmental Biology and Genetics, University of Minnesota, Minneapolis, MN 55905, USA
| | - Lu Miao
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - James E Bradner
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Ganesh V Raj
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Wayne D Tilley
- Dame Roma Mitchell Cancer Research Laboratories and Freemasons Foundation Centre for Mens' Health, School of Medicine, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Scott M Dehm
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55905, USA Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55905, USA
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102
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Reversal of PSA progression on abiraterone acetate through the administration with food in men with metastatic castration-resistant prostate cancer. Prostate Cancer Prostatic Dis 2015; 18:161-6. [DOI: 10.1038/pcan.2015.7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 12/17/2014] [Accepted: 01/12/2015] [Indexed: 11/08/2022]
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103
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Diagnostic value of SFRP1 as a favorable predictive and prognostic biomarker in patients with prostate cancer. PLoS One 2015; 10:e0118276. [PMID: 25719802 PMCID: PMC4342152 DOI: 10.1371/journal.pone.0118276] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 01/12/2015] [Indexed: 11/22/2022] Open
Abstract
Growing genetic and molecular biological evidence suggests that the disruption of balance between Secreted Frizzled-Related Protein-1 (SFRP1) and β-catenin plays an important role in the initiation and development of multiple cancers. The aim of this study was to examine whether the expression of SFRP1 and β-catenin is associated with the clinical-pathologic features of patients with prostate cancer (PCa), and to evaluate their potential roles as predictive and prognostic biomarkers. In this study, a total of 61 patients with PCa and 10 patients with benign prostatic hyperplasia were included, and we showed that the expression of SFRP1 and β-catenin was correlated with the Gleason score, survival rate and response for endocrine therapy of PCa. The survival rates of PCa patients with low SFRP1 expression (P = 0.016) or high β-catenin expression (P = 0.004) were significantly poorer. A negative correlation (r = -0.275, P = 0.032) between SFRP1 and β-catenin was observed by Chi-square test. Multivariate analysis suggested that SFRP1 (hazard ratio, 0.429; 95% confidence intervals, 0.227–0.812; P = 0.009) may serve as an independent predictive and prognostic factor for PCa. We also showed that the protein and mRNA levels of SFRP1 in androgen-dependent PCa cell line LNCaP were significantly higher than those in androgen-independent PCa cell lines DU145 and PC3. However, the protein level of β-catenin in LNCaP cells was significantly lower than that in DU145 and PC3 cells, and no significant difference of β-catenin mRNA level was observed in LNCaP, DU145 and PC3 cells. Bisulfite sequencing PCR assay revealed significantly lower methylation level of SFRP1 promoter in LNCaP cells than that in DU145 and PC3 cells. Taken together, these findings suggest that SFRP1, which expression inversely correlates with that of β-catenin, is a favorable predictive and prognostic biomarker.
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104
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Zhang T, Dhawan MS, Healy P, George DJ, Harrison MR, Oldan J, Chin B, Armstrong AJ. Exploring the Clinical Benefit of Docetaxel or Enzalutamide After Disease Progression During Abiraterone Acetate and Prednisone Treatment in Men With Metastatic Castration-Resistant Prostate Cancer. Clin Genitourin Cancer 2015; 13:392-399. [PMID: 25708161 DOI: 10.1016/j.clgc.2015.01.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 01/11/2015] [Accepted: 01/16/2015] [Indexed: 10/24/2022]
Abstract
BACKGROUND Abiraterone acetate (AA) has demonstrated improved outcomes in men with metastatic castration-resistant prostate cancer (mCRPC). However, data are lacking on the effect of AA on subsequent efficacy of enzalutamide or docetaxel. PATIENTS AND METHODS We included men with mCRPC who received AA and subsequent enzalutamide or docetaxel by August 12, 2013. Patients were separated into 3 groups: group A, treated with AA then enzalutamide before chemotherapy; group B, treated with AA then docetaxel; and group C, treated with AA and enzalutamide after chemotherapy. The primary objective was to describe the response and overall survival with subsequent therapy. RESULTS There were 28 evaluable patients who received enzalutamide after AA (9 in group A and 19 in group C) and 13 patients who received docetaxel after AA (group B). Group A patients had more visceral disease and higher baseline prostate-specific antigen (PSA) levels, and group C men had a higher level of pain and multiple poor prognostic features. Median progression-free survival was 3.6, 5.1, and 2.8 months, respectively, and median overall survival was 8.5, not reached, and 9.6 months, respectively. A ≥ 50% PSA decline was achieved in 11%, 63%, and 5% of group A, B, and C patients, respectively. Radiographic or clinical progression as best response was noted in 55.5%, 30.8%, and 68.4% in each respective group. CONCLUSION In this chart review of consecutive men with progressive mCRPC after AA, we found modest activity for enzalutamide and docetaxel, with clear cross-resistance for AA and enzalutamide. These data might inform the complex treatment decisions after AA treatment.
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Affiliation(s)
- Tian Zhang
- Duke Cancer Institute, Divisions of Medical Oncology and Urology, Departments of Medicine and Surgery, Duke University Medical Center, Durham, NC
| | | | - Patrick Healy
- Duke Cancer Institute, Divisions of Medical Oncology and Urology, Departments of Medicine and Surgery, Duke University Medical Center, Durham, NC
| | - Daniel J George
- Duke Cancer Institute, Divisions of Medical Oncology and Urology, Departments of Medicine and Surgery, Duke University Medical Center, Durham, NC
| | - Michael R Harrison
- Duke Cancer Institute, Divisions of Medical Oncology and Urology, Departments of Medicine and Surgery, Duke University Medical Center, Durham, NC
| | - Jorge Oldan
- Department of Radiology, Duke University Medical Center, Durham, NC
| | - Bennett Chin
- Department of Radiology, Duke University Medical Center, Durham, NC
| | - Andrew J Armstrong
- Duke Cancer Institute, Divisions of Medical Oncology and Urology, Departments of Medicine and Surgery, Duke University Medical Center, Durham, NC.
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105
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Munoz J, Wheler JJ, Kurzrock R. Androgen receptors beyond prostate cancer: an old marker as a new target. Oncotarget 2015; 6:592-603. [PMID: 25595907 PMCID: PMC4359241 DOI: 10.18632/oncotarget.2831] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 11/14/2014] [Indexed: 12/25/2022] Open
Abstract
Androgen receptors (ARs) play a critical role in the development of prostate cancer. Targeting ARs results in important salutary effects in this malignancy. Despite mounting evidence that ARs also participate in the pathogenesis and/or progression of diverse tumors, exploring the impact of hormonal manipulation of these receptors has not been widely pursued beyond prostate cancer. This review describes patterns of AR expression in a spectrum of cancers, and the potential to exploit this knowledge in the clinical therapeutic setting.
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Affiliation(s)
- Javier Munoz
- Hematology-Oncology, Banner MD Anderson Cancer Center, Gilbert, Arizona
| | - Jennifer J. Wheler
- Department of Investigational Cancer Therapeutics (Phase I Clinical Trials Program), The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Razelle Kurzrock
- Center for Personalized Cancer Therapy, Division and Hematology and Oncology, Moores Cancer Center, The University of California San Diego, La Jolla, California
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106
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Antonarakis ES. Predicting treatment response in castration-resistant prostate cancer: could androgen receptor variant-7 hold the key? Expert Rev Anticancer Ther 2014; 15:143-5. [PMID: 25547524 DOI: 10.1586/14737140.2015.999044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There is an emerging interest in understanding mechanisms of response and resistance to next-generation hormonal therapies: abiraterone and enzalutamide. While many explanations for resistance to these agents have been postulated, the importance of androgen receptor splice variants is gaining momentum. Androgen receptor (AR) splice variants are constitutively active isoforms of the AR that lack the ligand-binding domain yet retain their transcriptional activity in a ligand-independent fashion. Of these, AR variant-7 may be the most important, and has been implicated in primary resistance to abiraterone and enzalutamide in men with advanced prostate cancer. In this editorial, the clinical relevance of AR splice variant-7 (AR-V7) will be reviewed within the context of AR-directed therapies, and next steps for the analytical and clinical validation of this potential biomarker will be proposed.
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Affiliation(s)
- Emmanuel S Antonarakis
- Prostate Cancer Research Program, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, MD, USA
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107
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Zhang T, Zhu J, George DJ, Armstrong AJ. Enzalutamide versus abiraterone acetate for the treatment of men with metastatic castration-resistant prostate cancer. Expert Opin Pharmacother 2014; 16:473-85. [DOI: 10.1517/14656566.2015.995090] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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108
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Abstract
The majority of prostate cancers are hormone-dependent at diagnosis highlighting the central role of androgen signalling in this disease. Surprisingly, most forms of castration-resistant prostate cancer (CRPC) are still dependent on the androgen receptor (AR) for survival. Therefore, the advent of new AR-targeting drugs, such as enzalutamide, is certainly beneficial for the many patients with metastatic CRPC. Indeed, this compound provides a substantial survival benefit-but it is not curative. This Perspectives article describes the different ways through which cancer cells can become resistant to enzalutamide, such as AR truncation and other mutations, as well as by-pass of the AR dependence of prostate cancer cells through expression of the glucocorticoid receptor. The clinical relevance of these mechanisms and emerging questions concerning new therapeutic regimens in the treatment of metastatic CRPC are being discussed.
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109
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Affiliation(s)
- Peter S Nelson
- From the Fred Hutchinson Cancer Research Center, Seattle
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110
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Affiliation(s)
- Frank Claessens
- Molecular Endocrinology LaboratoryDepartment of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, Campus GHB ON1, PO Box 901, 3000 Leuven, BelgiumDame Roma Mitchell Cancer Research LaboratoriesSchool of Medicine, University of Adelaide, Adelaide, South Australia 5000, Australia
| | - Wayne Tilley
- Molecular Endocrinology LaboratoryDepartment of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, Campus GHB ON1, PO Box 901, 3000 Leuven, BelgiumDame Roma Mitchell Cancer Research LaboratoriesSchool of Medicine, University of Adelaide, Adelaide, South Australia 5000, Australia
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111
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Androgen receptor splice variants in the era of enzalutamide and abiraterone. Discov Oncol 2014; 5:265-73. [PMID: 25048254 DOI: 10.1007/s12672-014-0190-1] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 07/10/2014] [Indexed: 01/24/2023] Open
Abstract
The FDA approvals of enzalutamide and abiraterone have rapidly changed the clinical landscape of prostate cancer treatment. Both drugs were designed to further suppress androgen receptor (AR) signaling, which is restored following first-line androgen deprivation therapies. Resistance to enzalutamide and abiraterone, however, is again marked by a return of AR signaling, indicating a remarkable "addiction" of prostate cancer cells to the AR pathway. Several mechanisms of castration resistance have been uncovered in the past decades, featuring a wide spectrum of molecular alterations that may explain sustained AR signaling in castration-resistant prostate cancers (CRPC). Among these, the androgen receptor splice variants (AR-Vs), particularly variant 7 (AR-V7), have been implicated in resistance to enzalutamide and abiraterone in preclinical studies, and they cannot be targeted by currently available AR-directed drugs. Drug development for AR-V-associated CRPC may therefore be necessary to augment the preexisting treatment repertoire. In this mini-review, we will discuss general mechanisms of resistance to AR-directed therapies, with a focus on the role of androgen receptor splice variants in the new era of treating advanced prostate cancer with enzalutamide and abiraterone.
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