SETD2 deficiency accelerates MDS-associated leukemogenesis via S100a9 in NHD13 mice and predicts poor prognosis in MDS

SETD2, the histone H3 lysine 36 methyltransferase, previously identified by us, plays an important role in the pathogenesis of hematologic malignancies, but its role in myelodysplastic syndromes (MDSs) has been unclear. In this study, low expression of SETD2 correlated with shortened survival in patients with MDS, and the SETD2 levels in CD341 bone marrow cells of those patients were increased by decitabine. We knocked out Setd2 in NUP98-HOXD13 (NHD13) transgenic mice, which phenocopies human MDS, and found that loss of Setd2 accelerated the transformation of MDS into acute myeloid leukemia (AML). Loss of Setd2 enhanced the ability of NHD131 hematopoietic stem and progenitor cells (HSPCs) to self-renew, with increased symmetric self-renewal division and decreased differentiation and cell death. The growth ofMDS-associatedleukemiacellswasinhibitedthoughincreasingtheH3K36me3levelby using epigenetic modifying drugs. Furthermore, Setd2 deficiency upregulated hematopoietic stem cell signaling and downregulatedmyeloid differentiation pathways in theNHD131 HSPCs. Our RNA-seq and chromatin immunoprecipitation-seq analysis indicated that S100a9, the S100 calcium-binding protein, is a target gene of Setd2 and that the addition of recombinant S100a9 weakens the effect of Setd2 deficiency in theNHD131 HSPCs. In contrast, downregulation of S100a9 leads to decreases of its downstream targets, includingIkbaandJnk, whichinfluence the self-renewalanddifferentiation of HSPCs. Therefore, our resultsdemonstrated that SETD2 deficiency predicts poor prognosis in MDS and promotes the transformation of MDS into AML, which provides a potential therapeutic target for MDS-associated acute leukemia.