Project description:Prostate cancer (PCa) progression is driven by androgen receptor (AR) signaling. Unfortunately, androgen-deprivation therapy and the use of even more potent AR pathway inhibitors (ARPI) cannot bring about a cure. ARPI resistance (i.e. castration-resistant PCa, CRPC) will inevitably develop. Previously, we demonstrated that GRB10 is an AR transcriptionally-repressed gene that functionally contributes to CRPC development and ARPI resistance. GRB10 expression is elevated prior to CRPC development in our patient-derived xenograft models and is significantly upregulated in clinical CRPC samples. Here, we analyzed transcriptomic data from GRB10 knockdown in PCa cells and found that AR signaling is downregulated. While the mRNA expression of AR target genes decreased upon GRB10 knockdown, AR expression was not affected at the mRNA or protein level. We further found that phosphorylation of AR serine 81 (S81), which is critical for AR transcriptional activity, is decreased by GRB10 knockdown and increased by its overexpression. Luciferase assay using GRB10-knockdown cells also indicated reduced AR activity. Immunoprecipitation coupled with mass spectrometry revealed an interaction between GRB10 and the PP2A complex, which is a known phosphatase of AR. Further validations and analyses showed that GRB10 directly binds to the PP2Ac catalytic subunit with its PH domain. Mechanistically, GRB10 knockdown increased PP2Ac protein stability, which in turn decreased AR S81 phosphorylation and reduced AR activity. Our findings indicate a reciprocal feedback between GRB10 and AR signaling, implying the importance of GRB10 in PCa progression.
Project description:BPTF, the scaffolding subunit of the nucleosome remodeling factor (NURF) complex, has been implicated in the progression of several malignancies, but its role in prostate cancer (PCa) remains unclear. Here, we demonstrate that BPTF is upregulated in castration-resistant prostate cancer (CRPC) and promotes disease progression. RNA-seq revealed that BPTF primarily enhances the expression of androgen receptor (AR) target genes. ChIP-seq showed that BPTF increases AR binding at promoters, enhancers and super-enhancers. ATAC-seq further demonstrated that BPTF increases chromatin accessibility to facilitate AR binding, in part through SMARCA1, a catalytic subunit of the NURF complex. Notably, BPTF/AR co-bound regions are highly enriched for FOXA1 motifs but only weakly enriched for AR motifs. We further show that BPTF forms a protein complex with AR and FOXA1, in which FOXA1 recruits the BPTF-AR complex to chromatin, while BPTF stabilizes the AR-FOXA1 interaction. Importantly, BPTF interacts with AR through its bromodomain, and a BPTF bromodomain inhibitor disrupts this interaction, impairs AR signaling and suppresses PCa cell growth. In summary, our findings establish BPTF as a critical regulator of AR activity by promoting chromatin accessibility and stabilizing the AR-FOXA1 complex, highlighting BPTF as a potential therapeutic target in prostate cancer.
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 common cancer in men and AR downstream signalings promote prostate cancer cell proliferation. Oct1 is an AR interacting partner and regulates the transcriptional activity of AR. In order to investigate the Oct1 function in prostate cancer cells, we performed gene expression in AR-positive prostate cancer cell lines after siOct1 or pyrrole-imidazole (PI) polyamide targeting Oct1-binding treatment. We also treated cells with vehicle or androgen to analyze the effects of Oct1 on AR function. Observation of androgen dependent gene expression changes after treatment with siOct1 or polyamide targeting Oct1 with microarray.
Project description:Prostate cancer exhibits high prevalence and accounts for a high number of cancer-related deaths. The discovery and characterization of molecular determinants of aggressive prostate cancer represents an active area of research. The Immediate Early Response (IER) family of genes, which regulate Protein Phosphatase 2A (PP2A) activity, has emerged among the factors that influence cancer biology. Here, we show that the less studied member of this family, Immediate Early Response 5 like (IER5L), is upregulated in aggressive prostate cancer. Interestingly, the upregulation of IER5L expression exhibits a robust association with metastatic disease in prostate and is recapitulated in other cancer types. In line with this observation, IER5L silencing reduces foci formation, migration and invasion ability in a variety of human and murine prostate cancer cell lines. In vivo, using zebrafish and immunocompromised mice models, we demonstrate that IER5L is required for prostate cancer tumor growth, dissemination, and metastasis. Mechanistically, we characterize the transcriptomic and proteomic landscapes of IER5L-silenced cells. This approach allowed us to identify DNA replication and monomeric G protein regulators as downstream programs of IER5L through a pathway that is consistent with the regulation of PP2A. In sum, we report the alteration of IER5L in prostate cancer and beyond and provide biological and molecular evidence of its contribution to tumor aggressiveness.
Project description:Prostate cancer is the most common cancer in men and AR downstream signalings promote prostate cancer cell proliferation. Oct1 is an AR interacting partner and regulates the transcriptional activity of AR. In order to investigate the Oct1 function in prostate cancer cells, we performed gene expression in AR-positive prostate cancer cell lines after siOct1 or pyrrole-imidazole (PI) polyamide targeting Oct1-binding treatment. We also treated cells with vehicle or androgen to analyze the effects of Oct1 on AR function.
Project description:SPOP, an E3 ubiquitin ligase, acts as a prostate-specific tumor suppressor with several key substrates mediating oncogenic function. However, the mechanisms underlying SPOP regulation are largely unknown. Here, we have identified G3BP1 as an interactor of SPOP and functions as a competitive inhibitor of Cul3SPOP, suggesting a distinctive mode of Cul3SPOP inactivation in prostate cancer (PCa). Transcriptomic analysis and functional studies reveal a G3BP1-SPOP ubiquitin signaling axis that promotes PCa progression through activating AR signaling. Moreover, AR directly upregulates G3BP1 transcription to further amplify G3BP1-SPOP signaling in a feed-forward manner. Our study supports a fundamental role of G3BP1 in disabling the tumor suppressive Cul3SPOP, thus defining a PCa cohort independent of SPOP mutation. Therefore, there are significantly more PCa that are defective for SPOP ubiquitin ligase than previously appreciated, and these G3BP1high PCa are more susceptible to AR-targeted therapy.
Project description:Prostate cancer is the most common cancer in men and AR downstream signalings promote prostate cancer cell proliferation.We performed ChIP-seq analysis to investigate the role of AR and histone modifications.In addition, by siRNA mediated knockdown of AR-associated factors, changes of AR-binding sites in prostate cancer cells were analyzed.. ChIP-sequence analysis of AR and its associated factors in prostate cancer cells