Disruption of BRD4 at H3K27Ac-enriched enhancer region correlates with decreased c-Myc expression in Merkel cell carcinoma |
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| Authors: | Deepanwita Sengupta Aarthi Kannan Malan Kern Mauricio A Moreno Emre Vural Brendan Stack Jr James Y Suen Alan J Tackett Ling Gao |
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| Affiliation: | 1.Department of Biochemistry and Molecular Biology; University of Arkansas for Medical Sciences; Little Rock, AR, USA;2.Department of Dermatology; University of Arkansas for Medical Sciences; Little Rock, AR, USA;3.College of Medicine; University of Arkansas for Medical Sciences; Little Rock, AR, USA;4.Department of Otolaryngology-Head and Neck Surgery; University of Arkansas for Medical Sciences; Little Rock, AR, USA |
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| Abstract: | Pathologic c-Myc expression is frequently detected in human cancers, including Merkel cell carcinoma (MCC), an aggressive skin cancer with no cure for metastatic disease. Bromodomain protein 4 (BRD4) regulates gene transcription by binding to acetylated histone H3 lysine 27 (H3K27Ac) on the chromatin. Super-enhancers of transcription are identified by enrichment of H3K27Ac. BET inhibitor JQ1 disrupts BRD4 association with super-enhancers, downregulates proto-oncogenes, such as c-Myc, and displays antitumor activity in preclinical animal models of human cancers. Here we show that an enhancer proximal to the c-Myc promoter is enriched in H3K27Ac and associated with high occupancy of BRD4, and coincides with a putative c-Myc super-enhancer in MCC cells. This observation is mirrored in tumors from MCC patients. Importantly, depleted BRD4 occupancy at the putative c-Myc super-enhancer region by JQ1 correlates with decreased c-Myc expression. Thus, our study provides initial evidence that super-enhancers regulate c-Myc expression in MCC. |
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| Keywords: | BET inhibitor BRD4 H3K27Ac JQ1 Merkel cell carcinoma super-enhancer |
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