Loss of LCMT1 and biased protein phosphatase 2A heterotrimerization drive prostate cancer progression and therapy resistance
Ontology highlight
ABSTRACT: The first line of therapy for advanced prostate cancer (PCa) is androgen-deprivation therapy (ADT) through surgical or chemical castration; however, in the majority of cases, tumors relapse in a hormone refractory or castration resistant prostate cancer (CRPC) form. Once the PCa has recurred in CRPC form, it progresses to a highly aggressive disease with frequent metastasis and poses an increased risk of morbidity and death. This study shows that the loss of PP2Acα methylation in enzalutamide (Enza)-resistant CRPC cells plays a central role in imparting the resistant to the cancer cells by stabilizing the interaction of MED1, BRD4, and AR associated transcriptional complex, thereby amplifying the oncogenic AR transcriptional output through chromatin re-modulatory mechanism. Further, this study demonstrates that targeting the PP2ACα regulatory mechanisms or its downstream epigenetic effectors/mechanisms abolish the enzalutamide-resistance phenotype, thus paving the way for the development of more effective therapeutics to curtail mCRPC. The below given experiments validate the above findings.
Project description:The first line of therapy for advanced prostate cancer (PCa) is androgen-deprivation therapy (ADT) through surgical or chemical castration; however, in the majority of cases, tumors relapse in a hormone refractory or castration resistant prostate cancer (CRPC) form. Once the PCa has recurred in CRPC form, it progresses to a highly aggressive disease with frequent metastasis and poses an increased risk of morbidity and death This study shows that the loss of PP2Acα methylation in enzalutamide (Enza)-resistant CRPC cells plays a central role in imparting the resistant to the cancer cells by stabilizing the interaction of MED1, BRD4, and AR associated transcriptional complex, thereby amplifying the oncogenic AR transcriptional output through chromatin re-modulatory mechanism. Further, this study demonstrates that targeting the PP2ACα regulatory mechanisms or its downstream epigenetic effectors/mechanisms abolish the enzalutamide-resistance phenotype, thus paving the way for the development of more effective therapeutics to curtail mCRPC. The below given experiments validate the above findings.
Project description:Prostate cancer is the most commonly diagnosed and second-most lethal cancer among men in the United States. The vast majority of prostate cancer deaths are due to castration-resistant prostate cancer (CRPC) â?? the lethal form of the disease that has progressed despite therapies that interfere with activation of androgen receptor (AR) signaling. One emergent resistance mechanism to medical castration is synthesis of intratumoral androgens that activate the AR. This insight led to the development of the AR antagonist enzalutamide. However, resistance to enzalutamide invariably develops, and disease progression is nearly universal. One mechanism of resistance to enzalutamide is an F877L mutation in the AR ligand-binding domain that can convert enzalutamide to an agonist of AR activity. However, mechanisms that contribute to the agonist switch had not been fully clarified, and there were no therapies to block AR F877L. Using cell line models of castration-resistant prostate cancer (CRPC), we determined that cellular androgen content influences enzalutamide agonism of mutant F877L AR. Further, enzalutamide treatment of AR F877L-expressing cell lines recapitulated the effects of androgen activation of F877L AR or wild-type AR. Because the BET bromodomain inhibitor JQ-1 was previously shown to block androgen activation of wild-type AR, we tested JQ-1 in AR F877L-expressing CRPC models. We determined that JQ-1 suppressed androgen or enzalutamide activation of mutant F877L AR and suppressed growth of mutant F877L AR CRPC tumors in vivo, demonstrating a new strategy to treat tumors harboring this mutation. RNA-seq profiles of prostate cancer cell lines to understand gene expression associated with enzalutamide treatment
Project description:Enzalutamide (ENZA) is a potent second-generation antiandrogen commonly used to treat hormone-sensitive and castration-resistant prostate cancer (CRPC) patients. While initially effective, the response is only temporary and the disease almost always develops resistance. Given that many ENZA-resistant tumors are not driven by specific somatic mutations, there is increasing evidence that epigenetic factors can cause ENZA resistance. To explore how resistance arises we systematically tested all the epigenetic modifiers in castration-resistant and ENZA-resistant prostate cancer models using a custom epigenetic CRISPR library. From this, we identified and validated numerous epigenetic modifiers that were selectivity essential including SMARCC2, a core component of the SWI/SNF complex (or BAF complex) that regulates gene expression by altering DNA accessibility. Additionally, our data demonstrated canonical BAF complex dependency in ENZA-resistance that was also observed following the loss of DPF2, a canonical BAF-specific component. We showed that the chromatin occupancy of SMARCC2 and BRG1 was expanded in acquired ENZA resistance to the regions that overlap with transcriptional activity and CRPC-associated transcription factors that are significantly accessible in CRPC patients. Overall, our study revealed a regulatory role for SMARCC2 in ENZA-resistant prostate cancer and demonstrated the feasibility of targeting the SWI/SNF complex in late-stage PCa.
Project description:Enzalutamide (ENZA) is a potent second-generation antiandrogen commonly used to treat hormone-sensitive and castration-resistant prostate cancer (CRPC) patients. While initially effective, the response is only temporary and the disease almost always develops resistance. Given that many ENZA-resistant tumors are not driven by specific somatic mutations, there is increasing evidence that epigenetic factors can cause ENZA resistance. To explore how resistance arises we systematically tested all the epigenetic modifiers in castration-resistant and ENZA-resistant prostate cancer models using a custom epigenetic CRISPR library. From this, we identified and validated numerous epigenetic modifiers that were selectivity essential including SMARCC2, a core component of the SWI/SNF complex (or BAF complex) that regulates gene expression by altering DNA accessibility. Additionally, our data demonstrated canonical BAF complex dependency in ENZA-resistance that was also observed following the loss of DPF2, a canonical BAF-specific component. We showed that the chromatin occupancy of SMARCC2 and BRG1 was expanded in acquired ENZA resistance to the regions that overlap with transcriptional activity and CRPC-associated transcription factors that are significantly accessible in CRPC patients. Overall, our study revealed a regulatory role for SMARCC2 in ENZA-resistant prostate cancer and demonstrated the feasibility of targeting the SWI/SNF complex in late-stage PCa.
Project description:The androgen receptor (AR) is overexpressed and hyperactivated in human castration-resistant prostate cancer (CRPC). However, the determinants of AR overexpression in CRPC are poorly defined. Here we show that retinoic acid receptorârelated orphan receptor γ (ROR-γ) is overexpressed and amplified in metastatic CRPC tumors, and that ROR-γ drives AR expression in the tumors. ROR-γ recruits nuclear receptor coactivator 1 and 3 (NCOA1 and NCOA3, also known as SRC-1 and SRC-3) to an ARâROR response element (RORE) to stimulate AR gene transcription. ROR-γ antagonists suppress the expression of both AR and its variant AR-V7 in prostate cancer (PCa) cell lines and tumors. ROR-γ antagonists also markedly diminish genome-wide AR binding, H3K27ac abundance and expression of the AR target gene network. Finally, ROR-γ antagonists suppressed tumor growth in multiple AR-expressing, but not AR-negative, xenograft PCa models, and they effectively sensitized CRPC tumors to enzalutamide, without overt toxicity in mice. Taken together, these results establish ROR-γ as a key player in CRPC by acting upstream of AR and as a potential therapeutic target for advanced PCa. A total of 6 samples were analyzed in this study. The study included one cell line C4-2B. C4-2B cells were cultured in medium containing vehicle control and/or SR2211 and/or XY011 and/or Enzalutamide (ENZ). The untreated C4-2B cells served as controls for the study.
Project description:To inhibit the re-activation of AR-promoted tumor growth via residual androgens, more potent AR antagonists and inhibitors for androgen synthesis have been developed in the decades. While these second-generation antagonists/inhibitors showed some effectiveness clinically, they also induced more diverse castration-resistant prostate cancer (CRPC) phenotypes. Specifically, a subpopulation of AR- and neuroendocrine (NE)-null PC cells, DNPC, occurs frequently in CRPC patients treated with abiraterone and enzalutamide, increasing metastatic CRPC incidences and the mortality of prostate adenocarcinoma (PCa). Understanding the mechanisms for DNPC will directly improve clinical outcomes.
Project description:The androgen receptor (AR) is overexpressed and hyperactivated in human castration-resistant prostate cancer (CRPC). However, the determinants of AR overexpression in CRPC are poorly defined. Here we show that retinoic acid receptorârelated orphan receptor γ (ROR-γ) is overexpressed and amplified in metastatic CRPC tumors, and that ROR-γ drives AR expression in the tumors. ROR-γ recruits nuclear receptor coactivator 1 and 3 (NCOA1 and NCOA3, also known as SRC-1 and SRC-3) to an ARâROR response element (RORE) to stimulate AR gene transcription. ROR-γ antagonists suppress the expression of both AR and its variant AR-V7 in prostate cancer (PCa) cell lines and tumors. ROR-γ antagonists also markedly diminish genome-wide AR binding, H3K27ac abundance and expression of the AR target gene network. Finally, ROR-γ antagonists suppressed tumor growth in multiple AR-expressing, but not AR-negative, xenograft PCa models, and they effectively sensitized CRPC tumors to enzalutamide, without overt toxicity in mice. Taken together, these results establish ROR-γ as a key player in CRPC by acting upstream of AR and as a potential therapeutic target for advanced PCa. A total of 16 samples were analyzed in this study. The study included one cell line C4-2B. C4-2B cells were cultured in medium containing vehicle control or SR2211 (5 µM) for 24 hours, cells then were collected for ChIP seq assay
Project description:Molecular mechanisms underlying resistance to androgen deprivation therapy (ADT) and, in particular, to antiandrogen Enzalutamide, in treating castration-resistant prostate cancer (CRPC), remain incompletely understood. Through screening >120 CRPC patient samples, we observed 3 expression patterns of androgen receptor (AR) protein: primarily nuclear (nuc-AR), mixed nuclear/cytoplasmic expression (nuc/cyto-AR), and low/no expression (AR-/lo). Xenograft CRPC modeling in 4 models (i.e., LNCaP, VCaP, LAPC4, and LAPC9) recapitulated the 3 AR expression patterns in castration-resistant tumors developed from parental androgen-dependent tumors. Strikingly, although the 3 CRPC models that retained AR expression (LNCaP, VCaP, and LAPC4) responded, to different levels and in different kinetics, to Enzalutamide, the AR-/lo LAPC9 CRPC was completely refractory to Enzalutamide. By combining whole-genome RNA-Seq and biochemical analyses together with experimental combinatorial therapy in the LNCaP and LAPC9 models, we identified BCL-2 as a critical therapeutic target in both AR+/hi and AR-/lo, Enzalutamide-resistant CRPC models.
Project description:Prostate cancer is the most commonly diagnosed and second-most lethal cancer among men in the United States. The vast majority of prostate cancer deaths are due to castration-resistant prostate cancer (CRPC) – the lethal form of the disease that has progressed despite therapies that interfere with activation of androgen receptor (AR) signaling. One emergent resistance mechanism to medical castration is synthesis of intratumoral androgens that activate the AR. This insight led to the development of the AR antagonist enzalutamide. However, resistance to enzalutamide invariably develops, and disease progression is nearly universal. One mechanism of resistance to enzalutamide is an F877L mutation in the AR ligand-binding domain that can convert enzalutamide to an agonist of AR activity. However, mechanisms that contribute to the agonist switch had not been fully clarified, and there were no therapies to block AR F877L. Using cell line models of castration-resistant prostate cancer (CRPC), we determined that cellular androgen content influences enzalutamide agonism of mutant F877L AR. Further, enzalutamide treatment of AR F877L-expressing cell lines recapitulated the effects of androgen activation of F877L AR or wild-type AR. Because the BET bromodomain inhibitor JQ-1 was previously shown to block androgen activation of wild-type AR, we tested JQ-1 in AR F877L-expressing CRPC models. We determined that JQ-1 suppressed androgen or enzalutamide activation of mutant F877L AR and suppressed growth of mutant F877L AR CRPC tumors in vivo, demonstrating a new strategy to treat tumors harboring this mutation.
Project description:Androgen receptor (AR) signaling remains the key therapeutic target in the management of hormone-naïve advanced prostate cancer (PCa) and castration-resistant PCa (CRPC). Recently, landmark molecular features have been reported for CRPC, including the expression of constitutively active AR variants that lack the ligand-binding domain. Besides their role in CRPC, AR variants lead to the expression of genes involved in tumor progression. However, little is known about the specificity of their mode of action compared with that of wild-type AR (AR-WT). We performed AR transcriptome analyses in an androgen-dependent PCa cell line as well as cross-analyses with publicly available RNA-seq dataset and established that transcriptional repression capacity that was marked for AR-WT was pathologically lost by AR variants. Functional enrichment analyses allowed us to associate AR-WT repressive function to a panel of genes involved in cell adhesion and epithelial-to-mesenchymal transition. So, we postulate that a less documented AR-WT normal function in prostate epithelial cells could be the repression of a panel of genes linked to cell plasticity, and that this repressive function could be pathologically abrogated by AR variants in PCA.