SUMMARY Inhibition of anti-apoptotic proteins BCL-2 and MCL-1 to release pro-apoptotic protein BIM and reactivate cell death could potentially be an efficient strategy for the treatment of leukemia. Here, we show that a lncRNA, MORRBID , a selective transcriptional repressor of BIM , is overexpressed in human acute myeloid leukemia (AML), which is associated with poor overall survival. In both human and animal models, MORRBID hyperactivation correlates with two recurrent AML drivers, TET2 and FLT3 ITD . Mice with individual mutations of Tet2 or Flt3 ITD develop features of chronic myelomonocytic leukemia (CMML) and myeloproliferative neoplasm (MPN), respectively, and combined presence results in AML. We observe increased levels of Morrbid in murine models of CMML, MPN, and AML. Functionally, loss of Morrbid in these models induces increased expression of Bim and cell death in immature and mature myeloid cells, which results in reduced infiltration of leukemic cells in tissues and prolongs the survival of AML mice.

Diabetes mellitus (DM) is a risk factor for cancer. The role of DM-induced hyperglycemic stress (HG) in blood cancer is poorly understood. Epidemiologic studies show that individuals with DM are more likely to possess higher rate of mutations in genes found in pre-leukemic stem and progenitor cells (pre-LHSC/Ps) including TET2. TET2-mutant pre-LHSC/Ps require additional hits to evolve into a full-blown leukemia and/or aggressive myeloproliferative neoplasm (MPN). Intrinsic mutations have been shown to cooperate with Tet2 to promote leukemic transformation. However, extrinsic factors are poorly understood. Utilizing a mouse model bearing haploinsufficiency of Tet2, to mimic the human pre-LHSC/P condition and HG stress, in the form of an Ins2 Akita/+ mutation, which induces HG, we show that the compound mutant mice develop a lethal form of MPN and/or acute myeloid leukemia (AML). RNA-seq revealed that this is in part due to upregulation of pro-inflammatory pathways, thereby generating a feed-forward loop, including the expression of an anti-apoptotic lncRNA Morrbid. Morrbid loss in the compound mutants rescued the lethality and mitigated MPN/AML. We describe a mouse model for age-dependent AML/MPN and suggest that HG acts as an environmental driver for myeloid neoplasm, which could be prevented by reducing the expression of inflammation-related lncRNA Morrbid.

Diabetes mellitus (DM) is a risk factor for cancer development. However, the role of DM induced hyperglycemic stress (HG) in the development of blood cancer is poorly understood, largely due to lack of appropriate animal models. Epidemiologic studies show that individuals with DM are more likely to possess higher rate of mutations in genes found in pre-leukemic stem and progenitor cells (pre-LHSC/Ps) including in the epigenetic regulator TET2. TET2-mutant pre-LHSC/Ps require additional hits to evolve into a full-blown leukemia and/or aggressive myeloproliferative neoplasm (MPN). Cell intrinsic mutations have been shown to cooperate with Tet2 to promote leukemic transformation. However, the role of extrinsic factors is poorly understood. Utilizing a novel mouse model bearing haploinsufficiency of Tet2, to mimic the human pre-LHSC/P condition and HG stress, in the form of an Ins2Akita/+mutation, which induces HG and Type-1 DM, we show that the compound mutant mice develop a lethal form of MPN and/or acute myeloid leukemia (AML). RNA-seq revealed that this is in part due to upregulation of pro-inflammatory pathways, thereby generating a feed-forward loop, including the expression of an anti-apoptotic lncRNA Morrbid. Loss of Morrbid in the compound mutants rescues the lethality and mitigates the development of MPN/AML. Our results describe a novel mouse model for age-dependent AML/MPN and suggest that HG stress acts as an environmental driver for myeloid neoplasm, which could be effectively prevented by reducing the expression of inflammation-related lncRNA Morrbid. Disclosures No relevant conflicts of interest to declare.