CUX1 Deficiency Potentiates RAS Signaling to Drive Malignancy

-7/del(7q) is prevalent in high-risk myeloid neoplasms and frequently co-occurs with gain-of-function mutations in the RAS pathway. Herein, we identify a genetic interaction between RAS and the 7q-encoded transcription factor, CUX1, that encompasses hematopoietic malignancies and solid-tumors. Mice with both oncogenic NrasG12D and Cux1 knockdown developed accelerated myeloid malignancies with leukemic transformation. Oncogenic RAS imparts increased self-renewal on CUX1-deficient hematopoietic stem/progenitor cells (HSPCs). Reciprocally, CUX1 knockdown amplifies RAS signaling through reduction of negative regulators of RAS/PI3K signaling. Accordingly, NrasG12D;Cux1-knockdown HSPCs have heightened growth factor-sensitivity and downstream RAS pathway activation. Double mutant HSPCs were responsive to PIK3 or MEK inhibition. Similarly, low expression of CUX1 in primary AML samples correlates with sensitivity to the same inhibitors, suggesting a viable therapy for malignancies with CUX1 inactivation. This work demonstrates an unexpected convergence of an oncogene and tumor suppressor gene on the same pathway.