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  • 1
    Publication Date: 2015-12-25
    Description: Gain-of-function IDH mutations are initiating events that define major clinical and prognostic classes of gliomas. Mutant IDH protein produces a new onco-metabolite, 2-hydroxyglutarate, which interferes with iron-dependent hydroxylases, including the TET family of 5'-methylcytosine hydroxylases. TET enzymes catalyse a key step in the removal of DNA methylation. IDH mutant gliomas thus manifest a CpG island methylator phenotype (G-CIMP), although the functional importance of this altered epigenetic state remains unclear. Here we show that human IDH mutant gliomas exhibit hypermethylation at cohesin and CCCTC-binding factor (CTCF)-binding sites, compromising binding of this methylation-sensitive insulator protein. Reduced CTCF binding is associated with loss of insulation between topological domains and aberrant gene activation. We specifically demonstrate that loss of CTCF at a domain boundary permits a constitutive enhancer to interact aberrantly with the receptor tyrosine kinase gene PDGFRA, a prominent glioma oncogene. Treatment of IDH mutant gliomaspheres with a demethylating agent partially restores insulator function and downregulates PDGFRA. Conversely, CRISPR-mediated disruption of the CTCF motif in IDH wild-type gliomaspheres upregulates PDGFRA and increases proliferation. Our study suggests that IDH mutations promote gliomagenesis by disrupting chromosomal topology and allowing aberrant regulatory interactions that induce oncogene expression.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Flavahan, William A -- Drier, Yotam -- Liau, Brian B -- Gillespie, Shawn M -- Venteicher, Andrew S -- Stemmer-Rachamimov, Anat O -- Suva, Mario L -- Bernstein, Bradley E -- Howard Hughes Medical Institute/ -- England -- Nature. 2016 Jan 7;529(7584):110-4. doi: 10.1038/nature16490. Epub 2015 Dec 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology and Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA. ; Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA. ; Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA. ; Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26700815" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; CRISPR-Cas Systems/genetics ; Cell Cycle Proteins/metabolism ; Cell Proliferation/drug effects ; Cell Transformation, Neoplastic/drug effects ; Cells, Cultured ; Chromatin/drug effects/genetics/metabolism ; Chromosomal Proteins, Non-Histone/metabolism ; CpG Islands/genetics ; DNA Methylation/drug effects/genetics ; Down-Regulation/drug effects ; Enhancer Elements, Genetic/genetics ; Epigenesis, Genetic/drug effects ; *Gene Expression Regulation, Neoplastic/drug effects ; Glioma/drug therapy/*enzymology/*genetics/pathology ; Glutarates/metabolism ; Humans ; Insulator Elements/drug effects/*genetics ; Isocitrate Dehydrogenase/chemistry/*genetics/metabolism ; Mutation/*genetics ; Oncogenes/*genetics ; Phenotype ; Protein Binding ; Receptor, Platelet-Derived Growth Factor alpha/genetics ; Repressor Proteins/metabolism ; Up-Regulation
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2015-09-30
    Description: Super-enhancers (SEs), which are composed of large clusters of enhancers densely loaded with the Mediator complex, transcription factors and chromatin regulators, drive high expression of genes implicated in cell identity and disease, such as lineage-controlling transcription factors and oncogenes. BRD4 and CDK7 are positive regulators of SE-mediated transcription. By contrast, negative regulators of SE-associated genes have not been well described. Here we show that the Mediator-associated kinases cyclin-dependent kinase 8 (CDK8) and CDK19 restrain increased activation of key SE-associated genes in acute myeloid leukaemia (AML) cells. We report that the natural product cortistatin A (CA) selectively inhibits Mediator kinases, has anti-leukaemic activity in vitro and in vivo, and disproportionately induces upregulation of SE-associated genes in CA-sensitive AML cell lines but not in CA-insensitive cell lines. In AML cells, CA upregulated SE-associated genes with tumour suppressor and lineage-controlling functions, including the transcription factors CEBPA, IRF8, IRF1 and ETV6 (refs 6-8). The BRD4 inhibitor I-BET151 downregulated these SE-associated genes, yet also has anti-leukaemic activity. Individually increasing or decreasing the expression of these transcription factors suppressed AML cell growth, providing evidence that leukaemia cells are sensitive to the dosage of SE-associated genes. Our results demonstrate that Mediator kinases can negatively regulate SE-associated gene expression in specific cell types, and can be pharmacologically targeted as a therapeutic approach to AML.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4641525/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4641525/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pelish, Henry E -- Liau, Brian B -- Nitulescu, Ioana I -- Tangpeerachaikul, Anupong -- Poss, Zachary C -- Da Silva, Diogo H -- Caruso, Brittany T -- Arefolov, Alexander -- Fadeyi, Olugbeminiyi -- Christie, Amanda L -- Du, Karrie -- Banka, Deepti -- Schneider, Elisabeth V -- Jestel, Anja -- Zou, Ge -- Si, Chong -- Ebmeier, Christopher C -- Bronson, Roderick T -- Krivtsov, Andrei V -- Myers, Andrew G -- Kohl, Nancy E -- Kung, Andrew L -- Armstrong, Scott A -- Lemieux, Madeleine E -- Taatjes, Dylan J -- Shair, Matthew D -- CA66996/CA/NCI NIH HHS/ -- F31 CA180419/CA/NCI NIH HHS/ -- P01 CA066996/CA/NCI NIH HHS/ -- P30 CA008748/CA/NCI NIH HHS/ -- P30 CA046934/CA/NCI NIH HHS/ -- R01 CA170741/CA/NCI NIH HHS/ -- T32 GM08759/GM/NIGMS NIH HHS/ -- UL1 TR001082/TR/NCATS NIH HHS/ -- England -- Nature. 2015 Oct 8;526(7572):273-6. doi: 10.1038/nature14904. Epub 2015 Sep 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA. ; Department of Chemistry and Biochemistry, University of Colorado, Campus Box 596, Boulder, Colorado 80303, USA. ; Lurie Family Imaging Center, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA. ; Division of Hematology/Oncology, Children's Hospital, Boston, Massachusetts 02215, USA. ; Proteros Biostructures GmbH, Bunsenstrasse 7a, D-82152 Martinsried, Germany. ; Max-Planck-Institut fur Biochemie, Am Kloperspitz 18, D-82152 Martinsried, Germany. ; Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA. ; Cancer Biology and Genetics Program and Department of Pediatrics, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA. ; Department of Pediatrics, Columbia University Medical Center, New York, New York 10032, USA. ; Bioinfo, Plantagenet, Ontario K0B 1L0, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26416749" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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