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dc.contributor.advisorBernt, Kathrin M.
dc.contributor.advisorKutateladze, Tatiana
dc.contributor.authorKingsley, Molly Christine
dc.contributor.committeememberJordan, Craig
dc.contributor.committeememberErnst, Patricia
dc.contributor.committeememberHagman, James
dc.contributor.committeememberReisdorph, Nichole
dc.date.accessioned2020-01-14T15:44:31Z
dc.date.available2021-01-06T15:44:31Z
dc.date.submitted2019
dc.descriptionIncludes bibliographical references.
dc.descriptionFall
dc.description.abstractMutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) are found in 20-30% of adult acute myeloid leukemia (AML). Wild type IDH1/2 produce a-ketoglutarate (aKG), an important co-factor for many enzymes including DNA, RNA, and histone demethylases. Mutant IDH1/2 gain the ability to reduce aKG and produce the structurally similar 2-hydroxyglutarate (2HG), a competitive inhibitor of aKG. A previously reported consistent epigenetic alternation observed upon introduction of mutant IDH1/2 or treatment with 2HG is an increase in histone 3 lysine 79 di-methylation (H3K79me2). MLL-rearrangements (ML-r), are found in about 10-20% of adult AML. MLL-r encompass MLL-fusions (MLL-F) and MLL-partial tandem duplications (MLL-PTD), both of which share a dependency on the H3K79 methyltransferase DOT1L for H3K79me2 on target genes such as HOXA9 and MEIS1. Pharmacologic inhibition of DOT1L results in downregulation of MLL fusion/PTD target genes. Interestingly, 30% of MLL-PTD AML also contain a mutation in IDH1/2. Given this high rate of co-occurrence we hypothesized that mutant IDH1/2 would cooperate with MLL-r through an H3K79me2 mediated mechanism. Inhibitors for both DOT1L and mutant IDH1/2 are currently in clinical trials; therefore, it is important to understand how different oncogenes cooperate and which treatments are the most effective. Using murine models and viral overexpression we combined mutant IDH1/2 and MLL-fusions or PTDs and found no evidence of cooperation in our models. In fact, when mutant IDH1 was introduced into a fully established MLL-r AML, genes regulated by DOT1L were downregulated resulting in a significant growth impairment. Due to the fact that numerous enzymes are inhibited by 2HG, we overexpressed DOT1L in order to selectively increase H3K79me2 levels. Once again, a significant impairment of growth was observed. H3K79me2 ChIP-Seq revealed that DOT1L overexpression increased H3K79me2 peaks on non-target genes, blunting the difference between fusion targets and other genomic loci. Given the unexpected necessity of different H3K79me2 levels on MLL-F target and non-target genes, we analyzed global levels in a panel of patient samples. We found that patients with MLL-r had globally low H3K79me2 compared to other types of AML. In summary, we find an unexpected antagonism between MLL-r and mutations in IDH1/2 that may at least in part be explained by the need for MLL-r to maintain globally low, but locus specific high levels of H3K79me2. AML is a diverse disease with many patients presenting with unique combinations of mutations. The work presented here highlights that just because two mutations are found together does not mean they will cooperate. Knowing how different mutations interact is important for the rational design of new therapies.
dc.identifierKingsley_ucdenveramc_1639D_10697.pdf
dc.identifier.urihttps://hdl.handle.net/10968/4778
dc.languageEnglish
dc.publisherUniversity of Colorado at Denver, Anschutz Medical Campus. Health Sciences Library
dc.rightsCopyright of the original work is retained by the author.
dc.rights.accessEmbargo Expires: 01/06/2021
dc.subjectMLL
dc.subject.meshLeukemia, Myeloid, Acute
dc.subject.meshEpigenomics
dc.subject.meshIsocitrate Dehydrogenase
dc.titleBiological implications of distinctive H3K79me2 patterns in acute myeloid leukemia
dc.typeThesis
dcterms.embargo.expires2021-01-06
thesis.degree.disciplineMolecular Biology
thesis.degree.grantorUniversity of Colorado at Denver, Anschutz Medical Campus
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)


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