Quantitative analysis of bi-modal binding of BET proteins at promoters predicts I-BET sensitivity
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE120715 | GEO | 2019/07/22
REPOSITORIES: GEO
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Project description:BET-regulated transcriptome and BRD4, BRD2, BRD3 and Pol II ChIP-seq datasets in human ESCs before and after BET inhibition. Transcription factors and chromatin remodeling complexes are key determinants of embryonic stem cell (ESC) identity. In this study, we investigate the role of BRD4, a member of the bromodomain and extra-terminal domain (BET) family of epigenetic reader proteins, in control of ESC identity. We performed RNA-seq analyiss in the presense of small molecule inhibitors of BET proteins to show that BRD4 positively regulates the ESC transcriptome. We also integrated RNA-seq analysis with ChIP-sequencing datasets s for BRD4 (and for other BRD2 and BRD3) to demonstrate that BRD4 binds SEs and regulates the expression of SE-associated pluripotency genes. We have also conducted ChIP-seq analysis for Pol II binding to demonstrate that SE-associated genes depend on BRD4-dependent Pol II binding at TSS and gene body for their productive transcriptional elongation. Total RNA was extracted from samples using the RNeasy Qiagen kit according to the manufacturer’s instructions. Deep sequencing of RNA (1ug) from hESCs FGF- or MS436-treated at day 1 and day 5 was performed as described in (Higgin et al., 2010c). Samples were subjected to PolyA selection using magnetic oligo-dT beads. The resulting RNA samples were then used as input for library construction as described by the manufacturer (Illumina, CA, USA). RNA libraries were then sequenced on the GAIIx system using 50bp single reads. Chromatin for ChIP-sequencing was obtained from FGF-maintained hESCs, vehicle or MS417-treated (at 250nM concentration for 6h) (10 to 20x106 cells/IP). ChIP-Seq libraries were generated using standard Illumina kit and protocol as described in (Ntziachristos et al., 2012). We performed cluster amplification and single read 50 sequencing-method using the Illumina HiSeq 2000, following manufacturer’s protocols.
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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
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