Project description:In castration-resistant prostate cancer (CRPC), clinical response to androgen receptor (AR) antagonists is limited mainly due to AR-variants expression and restored AR signaling. The metabolite spermine is most abundant in prostate and it decreases as prostate cancer progresses, but its functions remain poorly understood. Here, we show spermine inhibits full-length androgen receptor (AR-FL) and androgen receptor splice variant 7 (AR-V7) signaling and suppresses CRPC cell proliferation by directly binding and inhibiting protein arginine methyltransferase PRMT1. Spermine reduces H4R3me2a modification at the AR locus and suppresses AR binding as well as H3K27ac modification levels at AR target genes. Spermine supplementation restrains CRPC growth in vivo. PRMT1 inhibition also suppresses AR-FL and AR-V7 signaling and reduces CRPC growth. Collectively, we demonstrate spermine as an anticancer metabolite by inhibiting PRMT1 to transcriptionally inhibit AR-FL and AR-V7 signaling in CRPC, and we indicate spermine and PRMT1 inhibition as powerful strategies overcoming limitations of current AR-based therapies in CRPC.
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:Background. Androgen receptor splice variant-7 (AR-V7) is a truncated form of the androgen receptor protein which lacks the ligand-binding domain, the target of enzalutamide and abiraterone, but remains constitutively active as a transcription factor. We hypothesized that detection of AR-V7 in circulating tumor cells (CTCs) from men with advanced prostate cancer would be associated with resistance to enzalutamide and abiraterone. Methods. We used quantitative reverse-transcription polymerase-chain-reaction (qRT-PCR) to interrogate CTCs for the presence or absence of AR-V7 from prospectively enrolled patients with metastatic castration-resistant prostate cancer initiating treatment with either enzalutamide or abiraterone. We examined associations between AR-V7 status and PSA response rates, PSA-progression-free-survival (PSA-PFS), clinical/radiographic-progression-free-survival (PFS), and overall survival (OS). Multivariable Cox regression analyses were performed to determine the independent effect of AR-V7 status on clinical outcomes. Results. Thirty-one enzalutamide-treated patients and thirty-one abiraterone-treated patients were enrolled, of which 38.7% and 19.4% had detectable AR-V7 from CTCs, respectively. Among men receiving enzalutamide, AR-V7–positive patients had inferior PSA response rates (0% vs 52.6%, P=0.004), PSA-PFS (median: 1.4 vs 6.0 months, P<0.001), PFS (median: 2.1 vs 6.1 months, P<0.001), and OS (median: 5.5 months vs not reached, P=0.002) compared to AR-V7–negative patients. Similarly, among men receiving abiraterone, AR-V7–positive patients had inferior PSA response rates (0% vs 68.0%, P=0.004), PSA-PFS (median: 1.3 months vs not reached, P<0.001), PFS (median: 2.3 months vs not reached, P<0.001), and OS (median: 10.6 months vs not reached, P=0.006). The negative prognostic impact of AR-V7 was maintained after adjusting for full-length-AR expression. Conclusions. Detection of AR-V7 in CTCs from patients with castration-resistant prostate cancer is associated with resistance to enzalutamide and abiraterone. A total of four metastatic castration-resistant prostate tumor samples from four patients were subjected to RNA-seq. Two samples were positive for androgen receptor splice variant 7 and the other two were negative for this variant.
Project description:The goal of this study was to determine how androgen receptor inhibition alters transcriptional programs in castration-resistant prostate cancer cells. 16D castration-resistant prostate cancer cells were grown in the presence of 10 micromolar enzalutamide for 24, 48, 96, 144 hours or for more than 2 months (long-term). Analysis shows that androgen receptor target genes are reduced with enzalutamide while metabolic genes are also differentially expressed.
Project description:Androgen receptor (AR) pathway inhibition remains the cornerstone for first- and second-line prostate cancer therapies. Although AR signaling inhibitors, such as enzalutamide and abiraterone extend survival in recurrent and castration-resistant prostate cancer (CRPC), durable and complete responses are rare. Resistance mechanisms employed by metastatic CRPC include amplification of AR and AR splice variants in AR-positive CRPC (ARPC) and conversion to AR-null phenotypes, such as double-negative prostate cancer (DNPC) and small cell or neuroendocrine prostate cancer (SCNPC). We have shown previously that DNPC can bypass AR-dependence through fibroblast growth factor (FGF) signaling. However, the role of the fibroblast growth factor receptor (FGFR) pathway in other molecular subtypes of CRPC has not been elucidated.
Project description:We report RNA sequencing data on serial biopsies of prostate cancer VCaP xenografts as the tumors pass from androgen-sensitivity (Pre-Cx), to castration resistance (CRPC, castration resistant prostate cancer), onto resistance to dual therapy with abiraterone plus enzalutamide (AER). From comparison of these RNAseq data sets, we were able to determine differentially expressed genes between the AER/CRPC and Pre-Cx states that could mediate resistance to androgen deprivation therapies.
Project description:The androgen receptor (AR) is a key driver of prostate cancer (PC), even in the state of castration-resistant PC (CRPC), and frequently even after treatment with second-line hormonal therapies such as abiraterone and enzalutamide. The persistence of AR activity via both ligand-dependent and ligand-independent (including constitutively active AR splice variants) mechanisms highlights the unmet need for alternative approaches to block AR signaling in CRPC. We investigated the transcription factor GATA2 as a regulator of AR signaling and a novel therapeutic target in PC. We demonstrate that GATA2 directly promotes AR expression (both full-length and splice variant), resulting in a strong positive correlation between GATA2 and AR expression in PC (cell lines and patient specimens). Conversely, GATA2 expression is repressed by androgen and AR, suggesting a negative feedback regulatory loop that, upon androgen deprivation, derepresses GATA2 to contribute to AR overexpression in CRPC. Simultaneously, GATA2 is necessary for optimal transcriptional activity of AR (both full-length and splice variant). GATA2 co-localizes with AR and FOXA1 on chromatin to enhance recruitment of steroid receptor coactivators (SRCs) and formation of the transcriptional holocomplex. In agreement with these important functions, high GATA2 expression and transcriptional activity predicted for worse clinical outcome in PC patients. A GATA2 small molecule inhibitor suppressed the expression and transcriptional function of AR (both full-length and splice variant) and exerted potent anticancer activity against PC cell lines. We propose pharmacological inhibition of GATA2 as a “first-in-field” approach to target AR expression and function and improve outcomes in CRPC. LNCaP cells were transfected with control siRNA (3), GATA2 siRNA (3) or AR siRNA for 72 hours.
Project description:The goal of this study was to determine how androgen receptor inhibition alters transcriptional programs in prostate cancer cells. LNCaP prostate cancer cells were grown in 10% charcoal-stripped serum (CSS) supplemented with 0.5 nanomolar dihydrotestosterone (DHT), in CSS without DHT modeling castration, with CSS + DHT but in the presence of 10 micromolar enzalutamide, or in CSS without DHT (castrated) and in the presence of enzalutamide for 72 hours. Analysis shows that androgen receptor target genes are reduced with castration, enzalutamide or the combination of castration + enzalutamide.
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:Posttranslational modifications of histones such as methylation regulate chromatin structure and gene expression. Methylation of histone lysine residues is generally performed by SET domain methyltransferases. Here, we identify the heterodimeric C21orf127/TRMT112 complex as a specific histone methyltransferase. Assembly of the seven-b-strand protein C21orf127 (also named Hemk2, N6amt1 or PrmC) with TRMT112 is essential to form an active enzyme, hereafter named KMT9 that writes the histone mark H4K12me1 in vitro and in vivo. The H4K12me1 mark is enriched at promoters of KMT9 target genes and co-localises with the active histone mark H4K12ac. By controlling expression of genes involved in energy metabolism, KMT9 regulates oxidative phosphorylation in androgen receptor-dependent and -independent prostate tumour cells. Importantly, KMT9 depletion severely affects proliferation of castration and enzalutamide-resistant prostate cancer cells and xenograft tumours. Together, our data link the writing of the H4K12me1 histone mark by KMT9 with KMT9-dependent gene expression, which in consequence regulates energy metabolism and proliferation. KMT9 executes these functions independently of androgen receptor and androgen signalling thus, providing a promising paradigm for the treatment of castration resistant prostate cancer.