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dc.contributor.authorPoole, Candace Jeanen
dc.date.accessioned2019-07-01T04:07:11Zen
dc.date.available2019-07-01T04:07:11Zen
dc.date.availableEmbargoed until 4/24/2021en
dc.date.issued2019-05en
dc.identifier.urihttp://hdl.handle.net/10675.2/622443en
dc.description.abstractAberrant DNA methylation is a characteristic feature of tumor cells. However, our knowledge of how DNA methylation patterns are established and maintained to contribute to tumorigenesis is limited. Inactivation of the c-MYC oncogene triggers tumor regression in T-cell acute lymphoblastic leukemia (T-ALL) resulting in dramatic changes to the chromatin landscape including DNA methylation. In this study, I investigated how MYC regulates DNA methylation and hydroxymethylation patterns to contribute to gene expression programs important for tumor maintenance in T-ALL and Burkitt lymphoma. I report that MYC maintains 5-methylcytosine (5mC) and 5-hydroxy-methylcytosine (5hmC) patterns by regulating the DNA methylation machinery, which is important for gene expression in T-ALL. DNA methyltransferases (DNMTs) initiate 5mC marks, while Ten-eleven translocation methylcytosine dioxygenases (TETs) oxidize 5mC to produce 5hmC as an intermediate modification, ultimately leading to active DNA de-methylation. I demonstrated that DNMT1 and DNMT3B are MYC target genes and that their expression is dependent on high MYC levels. Knockdown of DNMT3B in T-ALL reduced cell proliferation through cell cycle arrest and caused the reactivation of gene transcription through reversing promoter/CpG island methylation. Furthermore, I demonstrated that TET1 and TET2 expression is MYC-dependent, as high TET1 and low TET2 levels depend on oncogenic MYC. Knockdown of TET1 in T-ALL reduced cell proliferation through cell cycle arrest and caused genome-wide changes in 5mC and 5hmC corresponding to changes in gene programs important for ribosomal biosynthesis and protein synthesis. In contrast, ectopic expression of TET2 reduced tumor cell proliferation through apoptosis/necrosis and caused genome-wide changes in 5mC and 5hmC corresponding to changes in transcriptional regulatory gene programs. My finding that a coordinated interplay between components of the DNA methylation machinery is necessary for MYC-driven tumor maintenance highlights the potential of targeting specific DNMT or TET proteins for therapeutic strategies.en
dc.publisherAugusta Universityen
dc.subjectMolecular biologyen
dc.subjectBiochemistryen
dc.subjectcancer, DNA hydroxymethylation, DNA methylation, DNMTs, MYC, TETsen
dc.titleThe c-MYC oncogene deregulates global DNA methylation and hydroxymethylation to control genome-wide gene expression for tumor maintenance in leukemia/lymphomaen
dc.typedissertationen
dc.contributor.departmentBiomedical Sciencesen
dc.language.rfc3066enen
dc.date.updated2019-07-01T04:07:11Zen
dc.description.advisorvan Riggelen, Janen
dc.description.committeeLi, Honglinen
dc.description.committeeLiu, Kebinen
dc.description.committeeMartin, Pamelaen
dc.description.committeeShi, Huidongen
dc.description.committeeBrowning, Darrenen
dc.description.degreePh.D.en
refterms.dateFOA2021-04-28T12:26:08Z
dc.description.embargo04/25/2021en


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