FLT3-ITD mutations and TET2 loss synergistically alter global DNA methylation in AML

Studies of AML patient samples have shown that specific combinations of AML disease alleles confer an adverse outcome, however, in vivo models do not exist for the majority of common, poor-prognosis genotypes. Here we show that TET2/FLT3 mutations can cooperate to induce AML in vivo using a genetically engineered mouse model, and that this model has a defined stem-cell population with a characteristic transcriptional and epigenetic profile. TET2 and FLT3 mutations cooperate to induce site-specific changes in DNA methylation and gene expression, including at loci that regulate hematopoietic differentiation. We demonstrate that re-expression of genes that are silenced in TET2/FLT3-mutant AML restores normal differentiation, demonstrating that the epigenetic program of TET2/FLT3-mutant AML cells can be reversed in vitro and in vivo. Using ERRBS, we profiled genome-wide DNA methylation patterns of the hematopoietic stem cells (LSK) population in Wide-type, Flt3-IDT, Tet2-/-, and Tet2-/-Flt3-IDT mice, each in triplicates