DNMT3A mutants provide proliferating advantage with augmentation of self-renewal activity in the pathogenesis of AML in KMT2A-PTD-positive leukemic cells

Abstract Acute myeloid leukemia (AML) with partial tandem duplication of histone-lysine N-methyltransferase 2A ( KMT2A -PTD) is a subtype of AML and is associated with adverse survival, yet the molecular pathogenesis of KMT2A -PTD is not fully understood. DNA methyltransferase 3A ( DNMT3A ) is mutated in various myeloid neoplasms including AML, especially at the Arg882. Recently, it has been found that DNMT3A mutations frequently coexisted with KMT2A -PTD and are associated with inferior outcomes. We aimed to understand the biological role of DNMT3A mutation in KMT2A -PTD-positive cells. Herein, we found that overexpression of DNMT3A mutants (MT) in KMT2A -PTD-positive EOL-1 cells augmented cell proliferation and clonogenicity. Serial colony replating assays indicated that DNMT3A -MT increased the self-renewal ability of Kmt2a -PTD-expressing mouse bone marrow cells with immature morphology. At 10 months post bone marrow transplantation, mice with the combined Kmt2a- PTD and DNMT3A -MT showed hepatosplenomegaly and leukocytosis with a shorter latency compared to control and DNMT3A -wild-type. Gene expression microarray analyses of bone marrow samples from human AML with KMT2A -PTD/ DNMT3A -MT showed a stem cell signature and myeloid hematopoietic lineage with dysregulation of HOXB gene expression. In addition, human bone marrow AML cells carrying KMT2A -PTD/ DNMT3A -MT showed abnormal growth and augmented self-renewal activity in primary cell culture. The present study provides information underlying the pathogenic role of DNMT3A-MT with KMT2A-PTD in proliferating advantage with augmentation of self-renewal activity in human leukemia, which may help to better understand the disease and to design better therapy for AML patients with these mutations.