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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: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), entitled 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 requires high androgen receptor (AR) activity and is driven in part by downregulation of MYC. Using matched sequential patient biopsies, we show that high pre-treatment AR activity predicts downregulation of MYC, 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 can be overcome by alternating SPA with the AR inhibitor enzalutamide, which induces adaptive upregulation of AR and re-sensitizes prostate cancer to SPA. This work identifies high AR activity score as a predictive biomarker of response to BAT and supports a new treatment paradigm for prostate cancer involving alternating between AR inhibition and activation
2022-11-01 | GSE213443 | 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), entitled 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 requires high androgen receptor (AR) activity and is driven in part by downregulation of MYC. Using matched sequential patient biopsies, we show that high pre-treatment AR activity predicts downregulation of MYC, 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 can be overcome by alternating SPA with the AR inhibitor enzalutamide, which induces adaptive upregulation of AR and re-sensitizes prostate cancer to SPA. This work identifies high AR activity score as a predictive biomarker of response to BAT and supports a new treatment paradigm for prostate cancer involving alternating between AR inhibition and activation
2022-11-01 | GSE213437 | 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), entitled 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 requires high androgen receptor (AR) activity and is driven in part by downregulation of MYC. Using matched sequential patient biopsies, we show that high pre-treatment AR activity predicts downregulation of MYC, 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 can be overcome by alternating SPA with the AR inhibitor enzalutamide, which induces adaptive upregulation of AR and re-sensitizes prostate cancer to SPA. This work identifies high AR activity score as a predictive biomarker of response to BAT and supports a new treatment paradigm for prostate cancer involving alternating between AR inhibition and activation
2023-04-12 | GSE229555 | GEO
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
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.
| S-EPMC5405195 | biostudies-literature
Project description:Despite new treatments for castrate-resistant prostate cancer (CRPC), the prognosis of patients with CRPC remains bleak due to acquired resistance to androgen receptor (AR)-directed therapy. The glucocorticoid receptor (GR) and AR share several transcriptional targets, including the anti-apoptotic genes serum and glucocorticoid-regulated kinase 1 (SGK1) and Map kinase phosphatase 1 (MKP1)/dual specificity phosphatase 1 (DUSP1). Because GR expression increases in a subset of primary prostate cancer (PC) following androgen deprivation therapy, we sought to determine whether GR activation can contribute to resistance to AR-directed therapy. We studied CWR-22Rv1 and LAPC4 AR/GR-expressing PC cell lines following treatment with combinations of the androgen R1881, AR antagonist MDV3100, GR agonist dexamethasone, GR antagonists mifepristone and CORT 122928, or the SGK1 inhibitor GSK650394. Cell lines stably expressing GR (NR3C1)-targeted shRNA or ectopic SGK1-Flag were also studied in vivo. GR activation diminished the effects of the AR antagonist MDV3100 on tumor cell viability. In addition, GR activation increased prostate-specific antigen (PSA) secretion and induced SGKI and MKP1/DUSP gene expression. Glucocorticoid-mediated cell viability was diminished by a GR antagonist or by co-treatment with the SGK1 inhibitor GSK650394. In vivo, GR depletion delayed castrate-resistant tumor formation, while SGK1-Flag-overexpressing PC xenografts displayed accelerated castrate-resistant tumor initiation, supporting a role for SGK1 in GR-mediated CRPC progression. We studied several PC models before and following treatment with androgen blockade and found that increased GR expression and activity contributed to tumor-promoting PC cell viability. Increased GR-regulated SGK1 expression appears, at least in part, to mediate enhanced PC cell survival. Therefore, GR and/or SGK1 inhibition may be useful adjuncts to AR blockade for treating CRPC.
| S-EPMC4440041 | biostudies-literature
Project description: Not available
| S-EPMC8696212 | biostudies-literature
Project description:The androgen receptor (AR) has a crucial role in prostate cancer. RNA?binding protein?mediated post?transcriptional regulation is important in the initiation and development of cancer. The present study attempted to elucidate the mutual association of AR and RNA?binding protein quaking (QKI) in the development of prostate cancer. Dual?luciferase reporter demonstrated that AR can positively regulate the expression of QKI in prostate cancer cell lines due to its effective transcription regulating function. In addition, QKI may increase expression of AR by heat shock protein 90, which is a coactivator of AR, and silencing QKI can increase the sensitive of Casodex, which is an antagonist of AR in castration?resistant prostate cancer. This may be a new strategy for advanced prostate cancer.
| S-EPMC5984001 | biostudies-literature
Project description:Castration-resistant prostate cancer continues to rely on androgen receptor (AR) expression. AR plays a central role in the development of prostate cancer and progression to castration resistance during and after androgen deprivation therapy. Here, we identified miR-let-7c as a key regulator of expression of AR. miR-let-7c suppresses AR expression and activity in human prostate cancer cells by targeting its transcription via c-Myc. Suppression of AR by let-7c leads to decreased cell proliferation of human prostate cancer cells. Down-regulation of Let-7c in prostate cancer specimens is inversely correlated with AR expression, whereas the expression of Lin28 (a repressor of let-7) is correlated positively with AR expression. Our study demonstrates that the miRNA let-7c plays an important role in the regulation of androgen signaling in prostate cancer by down-regulating AR expression. These results suggest that reconstitution of miR-let-7c may aid in targeting enhanced and hypersensitive AR in advanced prostate cancer.
| S-EPMC3256915 | biostudies-literature