Project description:All current clinically approved androgen deprivation therapies for prostate cancer (PCa) target the C-terminal ligand-binding domain (LBD) of the androgen receptor (AR), although the N-terminal domain (NTD) is the main regulator of AR activity. Targeting the AR NTD directly is a challenge because of its intrinsic disordered nature and the lack of secondary structure and clefts for drugs to bind. Here, we make use of the cochaperone BAG1L that functions through the NTD to develop alternative AR inhibitors. We show that BAG1L binds to a short alpha-helical region of the AR NTD and regulates AR dynamics and the expression of AR target genes. We further show that disruption of the BAG1L-AR NTD action by a small molecule 2-(4-fluorophenyl)-5-(trifluoromethyl)-1,3-benzothiazole (A4B17) downregulates AR target gene expression and blocks proliferation of AR-positive PCa cells. Targeting a cochaperone as a surrogate to the AR NTD is therefore key to developing novel AR antagonists.
Project description:Targeting the activation function-1 (AF-1) at the N-terminus of the androgen receptor (AR) is an attractive therapeutic alternative to the current approaches to inhibit AR action in prostate cancer (PCa). Here we show that the AR AF-1 is bound by the BAG domain of the cochaperone Bag-1L. Mutations in this domain or loss of Bag-1L abrogates AR signaling and reduces PCa growth. Correspondingly, Bag-1L protein levels increase with progression of primary prostate tumors to castration-resistant PCa, correlating inversely with patient response to abiraterone therapy. Intriguingly, BAG domain residues important for its interaction with the AR AF-1 overlap a potentially druggable pocket of this protein. Bag-1L is therefore a putative therapeutic target for the inhibition of AR AF-1 activity.
Project description:Targeting the activation function-1 (AF-1) at the N-terminus of the androgen receptor (AR) is an attractive therapeutic alternative to the current approaches to inhibit AR action in prostate cancer (PCa). Here we show that the AR AF-1 is bound by the BAG domain of the cochaperone Bag-1L. Mutations in this domain or loss of Bag-1L abrogates AR signaling and reduces PCa growth. Correspondingly, Bag-1L protein levels increase with progression of primary prostate tumors to castration-resistant PCa, correlating inversely with patient response to abiraterone therapy. Intriguingly, BAG domain residues important for its interaction with the AR AF-1 overlap a potentially druggable pocket of this protein. Bag-1L is therefore a putative therapeutic target for the inhibition of AR AF-1 activity.
Project description:Targeting the activation function-1 (AF-1) at the N-terminus of the androgen receptor (AR) is an attractive therapeutic alternative to the current approaches to inhibit AR action in prostate cancer (PCa). Here we show that the AR AF-1 is bound by the BAG domain of the cochaperone Bag-1L. Mutations in this domain or loss of Bag-1L abrogates AR signaling and reduces PCa growth. Correspondingly, Bag-1L protein levels increase with progression of primary prostate tumors to castration-resistant PCa, correlating inversely with patient response to abiraterone therapy. Intriguingly, BAG domain residues important for its interaction with the AR AF-1 overlap a potentially druggable pocket of this protein. Bag-1L is therefore a putative therapeutic target for the inhibition of AR AF-1 activity.
Project description:Prostate cancer patients undergoing androgen deprivation therapy almost invariably develop castration-resistant prostate cancer. Resistance occurs when mutations in the androgen receptor (AR) render anti-androgen drugs ineffective or when constitutively active splice variants lacking the androgen binding domain entirely (e.g. ARV7) is expressed. In this study, we are reporting the discovery of novel AR-NTD covalent inhibitor 1‐chloro‐3‐[(5‐([(2S)‐3‐chloro‐2‐hydroxypropyl]amino)naphthalen‐1‐yl)amino]propan‐2‐ol (VPC-220010) targeting the AR-N-terminal Domain (AR-NTD). VPC-220010 inhibits AR-mediated transcription of full length and truncated variant ARV7, downregulates AR response genes, and selectively reduces the growth of both full-length AR- and truncated AR-dependent prostate cancer cell lines. We show that VPC-220010 disrupts interactions between AR and its known coactivators and interactors, such as CHD4, FOXA1, ZMIZ1, and several SWI/SNF complex proteins. Taken together, our data suggest that VPC-220010 is a promising small molecule AR-NTD inhibitor for the treatment of CRPC.
Project description:A novel mechanism, Death Induced by Survival gene Elimination (DISE), has recently been described as a potential cancer therapy. DISE kills cancer cells through an RNA interference (RNAi) mechanism. We show that expression of certain shRNAs developed to target TMEFF2 promotes prostate cancer (PCa) cell death similar to DISE, and independently of TMEFF2 targeting/expression. In PCa cells, these shRNAs downregulate the androgen receptor (AR) and AR coregulatory genes, an effect that correlates with the presence of short seed matches in their 3’UTRs and which results in global androgen signaling inhibition and cell death. We have termed this mechanism Androgen Network DISE (AN-DISE). shL3, an shRNA to CD95L known to promote DISE in non-PCa cells, promotes AN-DISE in PCa cells by targeting the AR-signaling pathway.
Project description:Aim: We examined methylation changes in cell-free DNA (cfDNA) in metastatic castration resistant prostate cancer (mCRPC) during treatment. Patients and Methods: Genome-wide methylation analysis of sequentially collected cfDNA samples derived from mCRPC patients undergoing androgen-targeting therapy was performed. Results: Alterations in methylation states of genes previously implicated in prostate cancer progression were observed, and patients that maintained methylation changes throughout therapy tended to have a longer time to clinical progression (TTP). Importantly, we also report that markers associated with a highly aggressive form of the disease, Neuroendocrine-CRPC, were associated with a faster TTP. Conclusion: Our findings highlight the potential of monitoring the cfDNA methylome during therapy in mCRPC, which may serve as predictive markers of response to androgen-targeting agents.
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
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