TET-dioxygenase deficiency in oncogenesis and its targeting for tumor-selective therapeutics.
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ABSTRACT:
SUBMITTER: Guan Y
PROVIDER: S-EPMC7938524 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Ten-eleven translocation (TET) family enzymes (TET1, TET2, and TET3) oxidize 5-methylcytosine (5mC) and generate 5-hydroxymethylcytosine (5hmC) marks on the genome. Each TET protein also interacts with specific binding partners and partly plays their role independent of catalytic activity. Although the basic role of TET enzymes is well established now, the molecular mechanism and specific contribution of their catalytic and noncatalytic domains remain elusive. Here, by combining in silico and biochemical screening strategy, we have identified a small molecule compound, C35, as a first-in-class TET inhibitor that specifically blocks their catalytic activities. Using this inhibitor, we explored the enzymatic function of TET proteins during somatic cell reprogramming. Interestingly, we found that C35-mediated TET inactivation increased the efficiency of somatic cell programming without affecting TET complexes. Using high-throughput mRNA sequencing, we found that by targeting 5hmC repressive marks in the promoter regions, C35-mediated TET inhibition activates the transcription of the BMP-SMAD-ID signaling pathway, which may be responsible for promoting somatic cell reprogramming. These results suggest that C35 is an important tool for inducing somatic cell reprogramming, as well as for dissecting the other biological functions of TET enzymatic activities without affecting their other nonenzymatic roles.
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Project description:TET2 is frequently mutated in myeloid neoplasms. Genetic TET2 deficiency leads to skewed myeloid differentiation and clonal expansion, but minimal residual TET activity is critical for survival of neoplastic progenitor and stem cells. Consistent with mutual exclusivity of TET2 and neomorphic IDH1/2 mutations, here we report that IDH1/2 mutant-derived 2-hydroxyglutarate is synthetically lethal to TET-dioxygenase deficient cells. In addition, a TET-selective small molecule inhibitor decreased cytosine hydroxymethylation and restricted clonal outgrowth of TET2 mutant, but not normal hematopoietic precursor cells in vitro and in vivo. While TET-inhibitor phenocopied somatic TET2 mutations, its pharmacologic effects on normal stem cells were, unlike mutations, reversible. Treatment with TET inhibitor suppressed the clonal evolution of TET2 mutant cells in murine models and TET2-mutated human leukemia xenografts. These results suggest that TET inhibitors may constitute a new class of targeted agents in TET2 mutant neoplasia.
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Project description:To characterize target specificity of TETi76, we performed global gene expression analyses of K562TET2+/+ and TET2-/- control cells; TETi76 mimicked expression signatures generated by the loss of TET2 in K562. The addition of Ascorbic Acid (AA), known to enhance TET-dioxygenase activity, counteracted the changes induced by TETi76. In order to study the molecular pathway of synthetic lethality by TET-dioxygenase inhibition, natural TET2-/- mutant cell line SIGM5 was treated with TET inhibitor TETi76 and global gene expression analysis was performed by RNAseq. Result demostrate a significant upregulation of TNT-α signaling and the down regulation of Interferon-α signaling. Interestingly, we also observed significant up-modulation of oxidative stress response pathway genes consistent with the inhibition of dioxygenases. In particular, TETi76 treatment induces 8-fold increase of oxidative stress sensor NQO1 a NRF2 target gene that has been shown earlier to induce pro-apoptotic cell death in cancer cells.
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