EVI1 exerts distinct roles in AML via ERG and cyclin D1 promoting a chemoresistance and immune-suppressive environment

Aberrant expression of Ecotropic viral integration site 1 (EVI1+) is associated with dismal outcomes in acute myeloid leukemia (AML), whose mechanisms are partially understood. Using the GFP reporter system to monitor EVI1-promoter activity, we demonstrated Evi1high KMT2A-MLLT1 transformed AML cells possess distinct features from Evillow cells: the potential for aggressive disease independent of stem cell activity and resistance to cytotoxic chemotherapy, along with the consistent gene expression profiles. Chromatin-immunoprecipitation- and RNA-sequencing in EVI1-transformed (EVI1-) AML cells and normal hematopoietic cells combined with functional screening by cell proliferation-related short hairpin RNAs revealed that ETS transcription factor ERG and cyclin D1 were downstream targets and therapeutic vulnerabilities of EVI1+ AML. Silencing Erg in murine EVI1+ AML models severely impaired cell proliferation, chemoresistance, and leukemogenic capacity. Cyclin D1 is also requisite for efficient EVI1-AML development, associated with gene expression profiles related to chemokine production and interferon signature and T and NK cell exhaustion phenotype, depending on the interferon-γ/STAT1 pathway but not on CDK4/CDK6. Inhibiting the interferon-γ/STAT1 pathway alleviated immune exhaustion and impaired EVI1-AML development. Overexpression of EVI1 and cyclin D1 was associated with interferon-γ signature and increased expression of chemokines, with increased exhaustion molecules in T cells also in human AML datasets. These data collectively suggest that ERG and cyclin D1 play pivotal roles in the biology of EVI1+ AML, where ERG forms aggressive disease nature and chemoresistance, and cyclin D1 leads to interferon-γ signature and exhausted T cell phenotypes, which could be potentially targeted.