Project description:Men who develop metastatic castration-resistant prostate cancer (CRPC) invariably succumb to the disease. The development and progression to CRPC following androgen ablation therapy is predominantly driven by unregulated androgen receptor (AR) signaling. Despite the success of recently approved therapies targeting AR signaling, such as abiraterone and second-generation anti-androgens MDV3100 (enzalutamide), durable responses are limited, presumably due to acquired resistance. Recently, JQ1 and I-BET, two selective small molecule inhibitors that target the amino-terminal bromodomains of BRD4, have been shown to exhibit antiproliferative effects in a range of malignancies. Here we show that AR signaling-competent CRPC cell lines are preferentially sensitive to BET bromodomain inhibition. BRD4 physically interacts with the N-terminal domain of AR and can be disrupted by JQ1. Like the direct AR antagonist, MDV3100, JQ1 disrupted AR recruitment to target gene loci. In contrast to MDV3100, JQ1 functions downstream of AR, and more potently abrogated BRD4 localization to AR target loci and AR mediated gene transcription including induction of TMPRSS2-ERG and its oncogenic activity. In vivo, BET bromodomain inhibition was more efficacious than direct AR antagonism in CRPC xenograft models. Taken together, these studies provide a novel epigenetic approach for the concerted blockade of oncogenic drivers in advanced prostate cancer. Examination of ASH2L genome-wide binding in prostate cancer cells after AR stimulation.
Project description:Men who develop metastatic castration-resistant prostate cancer (CRPC) invariably succumb to the disease. The development and progression to CRPC following androgen ablation therapy is predominantly driven by unregulated androgen receptor (AR) signaling1-3. Despite the success of recently approved therapies targeting AR signaling such as abiraterone4-6 and second generation anti-androgens MDV3100 (enzalutamide)7,8, durable responses are limited, presumably due to acquired resistance. Recently JQ1 and I-BET, two selective small molecule inhibitors that target the amino-terminal bromodomains of BRD4, have been shown to exhibit antiproliferative effects in a range of malignancies9-12. Here we show that AR signaling-competent CRPC cell lines are preferentially sensitive to BET bromodomain inhibition. BRD4 physically interacts with the N-terminal domain of AR and can be disrupted by JQ111,13. Like the direct AR antagonist, MDV3100, JQ1 disrupted AR recruitment to target gene loci. In contrast to MDV3100, JQ1 functions downstream of AR, and more potently abrogated BRD4 localization to AR target loci and AR mediated gene transcription including induction of TMPRSS2-ERG and its oncogenic activity. In vivo, BET bromodomain inhibition was more efficacious than direct AR antagonism in CRPC xenograft models. Taken together, these studies provide a novel epigenetic approach for the concerted blockade of oncogenic drivers in advanced prostate cancer. Examination of AR, BRD2, BRD3, BRD4, ERG, RNA Pol II and H3K27ac in prostate cancer cells with respect to BET inhibitors
Project description:Men who develop metastatic castration-resistant prostate cancer (CRPC) invariably succumb to the disease. The development and progression to CRPC following androgen ablation therapy is predominantly driven by unregulated androgen receptor (AR) signaling1-3. Despite the success of recently approved therapies targeting AR signaling such as abiraterone4-6 and second generation anti-androgens MDV3100 (enzalutamide)7,8, durable responses are limited, presumably due to acquired resistance. Recently JQ1 and I-BET, two selective small molecule inhibitors that target the amino-terminal bromodomains of BRD4, have been shown to exhibit antiproliferative effects in a range of malignancies9-12. Here we show that AR signaling-competent CRPC cell lines are preferentially sensitive to BET bromodomain inhibition. BRD4 physically interacts with the N-terminal domain of AR and can be disrupted by JQ111,13. Like the direct AR antagonist, MDV3100, JQ1 disrupted AR recruitment to target gene loci. In contrast to MDV3100, JQ1 functions downstream of AR, and more potently abrogated BRD4 localization to AR target loci and AR mediated gene transcription including induction of TMPRSS2-ERG and its oncogenic activity. In vivo, BET bromodomain inhibition was more efficacious than direct AR antagonism in CRPC xenograft models. Taken together, these studies provide a novel epigenetic approach for the concerted blockade of oncogenic drivers in advanced prostate cancer. Two-color experiment, in duplicates
Project description:BET bromodomain inhibitors are known to block prostate cancer cell survival through suppression of c-Myc and androgen receptor (AR) function. However, little is known about other transcriptional modulators whose function is blocked by these drugs and the anti-tumor activity of BET bromodomain inhibition in AR-independent castration-resistant prostate cancers (CRPC), whose frequency may be increasing. In this study we determined that BET bromodomain inhibition suppresses survival of a diverse set of CRPC cell models, including those that do not express the AR or in which c-Myc is not suppressed. To identify additional transcriptional regulators whose suppression contributes to the anti-tumor effects of BET bromodomain inhibition, we treated multiple CRPC cell lines with the BET bromodomain inhibitor JQ1, measured genome-wide gene expression changes, and then used the Master Regulator Inference Algorithm (MARINa). This approach identified transcriptional regulators whose function is blocked by JQ1 and whose suppression recapitulates the effects of BET bromodomain inhibition. High Expression of these Master Regulators in aggressive human CRPC demonstrates their clinical relevance.
Project description:Xenografts are useful in vivo tumour models for investigating cancer progression, therapeutic responses and predicting anti-cancer drug response in patients with cancer of a similar phenotype. We have generated bulk RNA-seq data from LNCaP xenografts of a large and well-annotated prostate cancer progression study, investigating responsiveness and subsequent resistance to therapies targeting the androgen receptor (AR). LNCaP xenograft tumour establishment and initial growth are dependent on androgens in male mice (PRE-CX / pre-castration group). Upon castration, AR activity and tumour growth are suppressed (POST-CX / post-castration group), however, this initial responsiveness to castration reproducibly gives way to castration-resistance (CRPC / castration-resistant prostate cancer). Further treatment of CRPC with the AR targeting drug enzalutamide (ENZ) initially provides a therapeutic response (ENZ Sensitive; ENZS), however, resistance emerges in time (ENZ Resistant; ENZR).
Project description:Bromodomain and extraterminal proteins (BET) are epigenetic adaptors that play critical roles in gene regulation. This protein family contains two conserved bromodomains which can mediate the interaction with acetylated histone lysine residues and/or other acetylated proteins, and one extraterminal (ET) domain. BET protein inhibition has been recognized as a promising therapeutic strategy for several diseases, including acute myeloid leukaemia, castration resistant prostate cancer, and triple negative breast cancer. BET inhibition by a specific inhibitor JQ1 caused an impairment in various brain functions but the underlying molecular mechanisms are not well understood. Among BET family members, BRD4 has been recognized for its prominent role in epigenetic regulation of gene expression. However, we have found an extensive functional redundancy and coordination among all three major BET family members (BRD2/3/4) during the activity-dependent gene induction in neurons, which is also reflected in learning and memory behavior. Our study further revealed the molecular hierarchy in the coordination of BET family proteins dissecting their distinctive functions during gene induction required for proper brain function and plasticity. Understanding the functional coordination of BET family proteins at the molecular level would be beneficial to the development of more selective interventions for various diseases that are caused by dysregulated epigenetic pathways.
Project description:Small cell lung cancer can be divided into several molecular subtypes based on the expression of four master transcription factors (ASCL1, NEUROD1, POU2F3, and YAP1). These master factors have not been directly druggable, and we hypothesized that targeting their transcriptional coactivator(s) could provide an alternative approach. Here, we identify that BET bromodomain proteins physically interact with NEUROD1 and function as transcriptional coactivators. Using CRISPR knockout and ChIP-seq, we demonstrate that NEUROD1 plays a critical role in defining the landscapes of BET bromodomain proteins in the SCLC genome. Targeting BET bromodomain proteins by BET inhibitors leads to broad suppression of the NEUROD1-target genes, especially those associated with superenhancers, and reduces SCLC growth in vitro and in vivo. LSAMP, a membrane protein in the IgLON family, was identified as one of the NEUROD1-target genes mediating BET inhibitor sensitivity in SCLC. Altogether, our study reveals that targeting transcriptional coactivators could be a novel approach to blocking the master transcription factors in SCLC for therapeutic purposes. The purpose of this part of the study was to investigate what genes are affected by BET inhibitor JQ1 in small cell lung cancer cell line COR-L279 (a SCLC-N subtype).