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Alterations of androgen receptor-regulated enhancer RNAs (eRNAs) contribute to enzalutamide resistance in castration-resistant prostate cancer.

ABSTRACT: Enzalutamide is a second-generation anti-androgen for treatment of castration-resistant prostate cancer (CPRC). It prolongs survival of CRPC patients, but its overall survival benefit is relatively modest (4.8 months) and by 24 months most patients progress on enzalutamide. To date, however, the molecular mechanisms underlying enzalutamide resistance remain elusive. Herein, we report enzalutamide treatment-induced alterations of androgen receptor (AR)-regulated enhancer RNAs (AR-eRNAs) and their roles in enzalutamide-resistant growth and survival of CRPC cells. AR chromatin immunoprecipitation and high throughput sequencing (ChIP-seq) and RNA-seq analyses revealed that 188 and 227 AR-eRNAs were differentially expressed in enzalutamide-resistant LNCaP and C4-2 cells, respectively. The AR-eRNAs upregulated in C4-2 cells and downregulated in LNCaP cells were selected through meta-analysis. Expression of AR-eRNAs and related mRNAs in the loci of FTO, LUZP2, MARC1 and NCAM2 were further verified by real-time RT-PCR. Silencing of LUZP2 inhibited, but silencing of MARC1 increased the growth of enzalutamide-resistant C4-2 cells. Intriguingly, meta-analysis showed that expression of LUZP2 mRNA increased in primary tumors compared to normal prostate tissues, but decreased again in metastatic CRPC. Our findings suggest that eRNA alteration profiling is a viable new approach to identify functional gene loci that may not only contribute to enzalutamide-resistant growth of CRPC, but also serve as new targets for CRPC therapy.

SUBMITTER: Zhao J

PROVIDER: S-EPMC5122410 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Alterations of androgen receptor-regulated enhancer RNAs (eRNAs) contribute to enzalutamide resistance in castration-resistant prostate cancer.

Zhao Jingwen J Zhao Yu Y Wang Liguo L Zhang Jun J Karnes R Jeffrey RJ Kohli Manish M Wang Guixia G Huang Haojie H

Oncotarget 20160601 25

Enzalutamide is a second-generation anti-androgen for treatment of castration-resistant prostate cancer (CPRC). It prolongs survival of CRPC patients, but its overall survival benefit is relatively modest (4.8 months) and by 24 months most patients progress on enzalutamide. To date, however, the molecular mechanisms underlying enzalutamide resistance remain elusive. Herein, we report enzalutamide treatment-induced alterations of androgen receptor (AR)-regulated enhancer RNAs (AR-eRNAs) and their ...[more]

PMID: 27221037

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Project description:Importance:The molecular landscape underpinning response to the androgen receptor (AR) antagonist enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC) is undefined. Consequently, there is an urgent need for practical biomarkers to guide therapy selection and elucidate resistance. Although tissue biopsies are impractical to perform routinely in the majority of patients with mCRPC, the analysis of plasma cell-free DNA (cfDNA) has recently emerged as a minimally invasive method to explore tumor characteristics. Objective:To reveal genomic characteristics from cfDNA associated with clinical outcomes during enzalutamide treatment. Design, Setting, and Participants:Plasma samples were obtained from August 4, 2013, to July 31, 2015, at a single academic institution (British Columbia Cancer Agency) from 65 patients with mCRPC. We collected temporal plasma samples (at baseline, 12 weeks, end of treatment) for circulating cfDNA and performed array comparative genomic hybridization copy number profiling and deep AR gene sequencing. Samples collected at end of treatment were also subjected to targeted sequencing of 19 prostate cancer-associated genes. Exposure:Enzalutamide, 160 mg, daily orally. Main Outcomes and Measures:Prostate-specific antigen response rate (decline ?50% from baseline confirmed ?3 weeks later). Radiographic (as per Prostate Cancer Working Group 2 Criteria) and/or clinical progression (defined as worsening disease-related symptoms necessitating a change in anticancer therapy and/or deterioration in Eastern Cooperative Group performance status ?2 levels). Results:The 65 patients had a median (interquartile range) age of 74 (68-79) years. Prostate-specific antigen response rate to enzalutamide treatment was 38% (25 of 65), while median clinical/radiographic progression-free survival was 3.5 (95% CI, 2.1-5.0) months. Cell-free DNA was isolated from 122 of 125 plasma samples, and targeted sequencing was successful in 119 of 122. AR mutations and/or copy number alterations were robustly detected in 48% (31 of 65) and 60% (18 of 30) of baseline and progression samples, respectively. Detection of AR amplification, heavily mutated AR (?2 mutations), and RB1 loss were associated with worse progression-free survival, with hazard ratios of 2.92 (95% CI, 1.59-5.37), 3.94 (95% CI, 1.46-10.64), and 4.46 (95% CI, 2.28-8.74), respectively. AR mutations exhibited clonal selection during treatment, including an increase in glucocorticoid-sensitive AR L702H and promiscuous AR T878A in patients with prior abiraterone treatment. At the time of progression, cfDNA sequencing revealed mutations or copy number changes in all patients tested, including clinically actionable alterations in DNA damage repair genes and PI3K pathway genes, and a high frequency (4 of 14) of activating CTNNB1 mutations. Conclusions and Relevance:Clinically informative genomic profiling of cfDNA was feasible in nearly all patients with mCRPC and can provide important insights into enzalutamide response and resistance.

Dataset Information

Alterations of androgen receptor-regulated enhancer RNAs (eRNAs) contribute to enzalutamide resistance in castration-resistant prostate cancer.

Publications

Alterations of androgen receptor-regulated enhancer RNAs (eRNAs) contribute to enzalutamide resistance in castration-resistant prostate cancer.

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