DNA Hydroxymethylation Profiling Reveals that WT1Mutations Result in Loss of TET2 Function in Acute Myeloid Leukemia

Somatic mutations in IDH1/IDH2and TET2result in impaired TET2-mediated conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC). The observation that WT1inactivating mutations anticorrelate with TET2/IDH1/IDH2mutations in acute myeloid leukemia (AML) led us to hypothesize that WT1 mutations may impact TET2 function. WT1mutant AML patients have reduced 5hmC levels similar to TET2/IDH1/IDH2mutant AML. These mutations are characterized by convergent, site-specific alterations in DNA hydroxymethylation, which drive differential gene expression more than alterations in DNA promoter methylation. WT1 overexpression increases global levels of 5hmC, and WT1 silencing reduced 5hmC levels. WT1 physically interacts with TET2 and TET3, and WT1 loss of function results in a similar hematopoietic differentiation phenotype as observed with TET2 deficiency. These data provide a role for WT1 in regulating DNA hydroxymethylation and suggest that TET2 IDH1/IDH2and WT1mutations define an AML subtype defined by dysregulated DNA hydroxymethylation.