Overexpression of c-Myc antagonises transcriptional output of the androgen receptor in prostate cancer
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE73995 | GEO | 2017/04/14
SECONDARY ACCESSION(S): PRJNA298680
REPOSITORIES: GEO
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Project description:Prostate cancer is the most common non-cutaneous cancer in men. The androgen receptor (AR) a ligand-activated transcription factor, constitutes the main drug target for advanced cases of the disease. However, a variety of other transcription factors and signalling networks have been shown to be altered in patients and to influence AR activity. The oncogenic transcription factor c-Myc has been studied extensively in multiple malignancies, but its impact on AR activity in prostate cancer remains elusive. In this study we assessed the impact of clinically relevant levels of c-Myc overexpression on AR activity and transcriptional output. We found that c-Myc and the AR share a substantial amount of binding sites, which exhibit enhancer-like characteristics. Interestingly, c-Myc overexpression altered global AR chromatin occupancy and antagonised a subset of androgen-induced genes. Furthermore, c-Myc overexpression modified histone marks, most notably H3K4me1 and H3K27me3. Lastly, we validated the antagonistic relationship between c-Myc and two AR target genes, KLK3 and GNMT, in patient samples.
2017-04-14 | GSE73917 | GEO
Project description:c-Myc overexpression LNCaP cells were treated with R1881 or R1881+Doxycycline (to induce c-Myc overexpression) and ChIP-seq studies were performed using antibodies against c-Myc, AR, H3K4me1, H3K4me3, H3K27ac and H3K27m3 Prostate cancer is the most common non-cutaneous cancer in men. The androgen receptor (AR) a ligand-activated transcription factor, constitutes the main drug target for advanced cases of the disease. However, a variety of other transcription factors and signalling networks have been shown to be altered in patients and to influence AR activity. The oncogenic transcription factor c-Myc has been studied extensively in multiple malignancies, but its impact on AR activity in prostate cancer remains elusive. In this study we assessed the impact of clinically relevant levels of c-Myc overexpression on AR activity and transcriptional output. We found that c-Myc and the AR share a substantial amount of binding sites, which exhibit enhancer-like characteristics. Interestingly, c-Myc overexpression altered global AR chromatin occupancy and antagonised a subset of androgen-induced genes. Furthermore, c-Myc overexpression modified histone marks, most notably H3K4me1 and H3K27me3. Lastly, we validated the antagonistic relationship between c-Myc and two AR target genes, KLK3 and GNMT, in patient samples.
2017-04-14 | GSE73994 | GEO
Project description:Prostate cancer (PCa) is the most common non-cutaneous cancer in men. The androgen receptor (AR), a ligand-activated transcription factor, constitutes the main drug target for advanced cases of the disease. However, a variety of other transcription factors and signaling networks have been shown to be altered in patients and to influence AR activity. Amongst these, the oncogenic transcription factor c-Myc has been studied extensively in multiple malignancies and elevated protein levels of c-Myc are commonly observed in PCa. Its impact on AR activity, however, remains elusive. In this study, we assessed the impact of c-Myc overexpression on AR activity and transcriptional output in a PCa cell line model and validated the antagonistic effect of c-MYC on AR-targets in patient samples. We found that c-Myc overexpression partially reprogrammed AR chromatin occupancy and was associated with altered histone marks distribution, most notably H3K4me1 and H3K27me3. We found c-Myc and the AR co-occupy a substantial number of binding sites and these exhibited enhancer-like characteristics. Interestingly, c-Myc overexpression antagonised clinically relevant AR target genes. Therefore, as an example, we validated the antagonistic relationship between c-Myc and two AR target genes, KLK3 (alias PSA, prostate specific antigen), and Glycine N-Methyltransferase (GNMT), in patient samples. Our findings provide unbiased evidence that MYC overexpression deregulates the AR transcriptional program, which is thought to be a driving force in PCa.
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Project description:Overexpression of c-Myc antagonises transcriptional output of the androgen receptor in prostate cancer
| PRJNA298680 | ENA
Project description:c-MYC (MYC) is a major driver of prostate cancer tumorigenesis and progression. Although MYC is overexpressed in both early and metastatic disease and associated with poor survival, its impact on prostate transcriptional reprogramming remains elusive. We demonstrate that MYC overexpression significantly diminishes the androgen receptor (AR) transcriptional program (the set of genes directly targeted by the AR protein) in luminal prostate cells without altering AR expression. Analyses of clinical specimens reveal that concurrent low AR and high MYC transcriptional programs accelerate prostate cancer progression toward a metastatic, castration-resistant disease. Data integration of single-cell transcriptomics together with ChIP-seq uncover an increase in RNA polymerase II (Pol II) promoter-proximal pausing at AR-dependent genes following MYC overexpression without an accompanying deactivation of AR-bound enhancers. Altogether, our findings suggest that MYC overexpression antagonizes the canonical AR transcriptional program and contributes to prostate tumor initiation and progression by disrupting transcriptional pause release at AR-regulated genes.
| S-EPMC9106722 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below.
2022-03-28 | GSE163146 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below.
2022-11-01 | GSE213444 | GEO
Project description:Testosterone is the canonical growth factor of prostate cancer but can paradoxically suppress its growth when present at supraphysiological levels. We have previously demonstrated that the cyclical administration of supraphysiological androgen (SPA), termed bipolar androgen therapy (BAT), can result in tumor regression and clinical benefit for patients with castration-resistant prostate cancer. However, predictors and mechanisms of response and resistance have been ill defined. Here, we show that growth inhibition of prostate cancer models by SPA required high androgen receptor (AR) activity and were driven in part by downregulation of MYC. Using matched sequential patient biopsies, we show that high pretreatment AR activity predicted downregulation of MYC, improved clinical response, and prolonged progression-free and overall survival for patients on BAT. BAT induced strong downregulation of AR in all patients, which is shown to be a primary mechanism of acquired resistance to SPA. Acquired resistance was overcome by alternating SPA with the AR inhibitor enzalutamide, which induced adaptive upregulation of AR and resensitized prostate cancer to SPA. This work identifies high AR activity as a predictive biomarker of response to BAT and supports a treatment paradigm for prostate cancer involving alternating between AR inhibition and activation.
| S-EPMC9711876 | biostudies-literature
Project description:OBJECTIVE:While prostate cancer does not occur more often in men with diabetes, survival is markedly reduced in this patient group. Androgen signaling is a known and major driver for prostate cancer progression. Therefore, we analyzed major components of the androgen signaling chain and cell proliferation in relation to type 2 diabetes. METHODS:Tumor content of 70 prostate tissue samples of men with type 2 diabetes and 59 samples of patients without diabetes was quantified by an experienced pathologist, and a subset of 51 samples was immunohistochemically stained for androgen receptor (AR). mRNA expression of AR, insulin receptor isoform A (IR-A) and B (IR-B), IGF-1 receptor (IGF1R), Cyp27A1 and Cyp7B1, PSA gene KLK3, PSMA gene FOLH1, Ki-67 gene MKI67, and estrogen receptor beta (ESR2) were analyzed by RT-qPCR. RESULTS:AR mRNA and protein expression were associated with the tumor content only in men with diabetes. AR expression also correlated with downstream targets PSA (KLK3) and PSMA (FOLH1) and increased cell proliferation. Only in diabetes, AR expression was correlated to higher IR-A/IR-B ratio and lower IR-B/IGF1R ratio, thus, in favor of the mitogenic isoforms. Reduced Cyp27A1 and increased Cyp7B1 expressions in tumor suggest lower levels of protective estrogen receptor ligands in diabetes. CONCLUSIONS:We report elevated androgen receptor signaling and activity presumably due to altered insulin/IGF-1 receptors and decreased levels of protective estrogen receptor ligands in prostate cancer in men with diabetes. Our results reveal new insights why these patients have a worse prognosis. These findings provide the basis for future clinical trials to investigate treatment response in patients with prostate cancer and diabetes.
| S-EPMC5985051 | biostudies-literature
Project description:The androgen receptor (AR) is the principal therapeutic target in prostate cancer. For the past 70 years, androgen deprivation therapy (ADT) has been the major therapeutic focus. However, some patients do not benefit, and those tumors that do initially respond to ADT eventually progress. One recently described mechanism of such an effect is growth and survival-promoting effects of the AR that are exerted independently of the AR ligands, testosterone and dihydrotestosterone. However, specific ligand-independent AR target genes that account for this effect were not well characterized. We show here that c-Myc, which is a key mediator of ligand-independent prostate cancer growth, is a key ligand-independent AR target gene. Using microarray analysis, we found that c-Myc and AR expression levels strongly correlated with each other in tumors from patients with castration-resistant prostate cancer (CRPC) progressing despite ADT. We confirmed that AR directly regulates c-Myc transcription in a ligand-independent manner, that AR and c-Myc suppression reduces ligand-independent prostate cancer cell growth, and that ectopic expression of c-Myc attenuates the anti-growth effects of AR suppression. Importantly, treatment with the bromodomain inhibitor JQ1 suppressed c-Myc function and suppressed ligand-independent prostate cancer cell survival. Our results define a new link between two critical proteins in prostate cancer - AR and c-Myc - and demonstrate the potential of AR and c-Myc-directed therapies to improve prostate cancer control.
| S-EPMC3660401 | biostudies-literature