C/EBP & alpha; Confers Dependence to Fatty Acid Anabolic Pathways and Vulnerability to Lipid Oxidative Stress-Induced Ferroptosis in FLT3-Mutant Leukemia

Although transcription factor CCAAT-enhancer binding protein & alpha; (C/EBP & alpha;) is criti-cal for normal and leukemic differentiation, its role in cell and metabolic homeosta-sis is largely unknown in cancer. Here, multiomics analyses uncovered a coordinated activation of C/ EBP & alpha; and Fms-like tyrosine kinase 3 (FLT3) that increased lipid anabolism in vivo and in patients with FLT3-mutant acute myeloid leukemia (AML). Mechanistically, C/EBP & alpha; regulated the fatty acid synthase (FASN)-stearoyl-CoA desaturase (SCD) axis to promote fatty acid (FA) biosynthesis and desatura-tion. We further demonstrated that FLT3 or C/EBP & alpha; inactivation decreased monounsaturated FA incorporation to membrane phospholipids through SCD downregulation. Consequently, SCD inhibition enhanced susceptibility to lipid redox stress that was exploited by combining FLT3 and glutathione per-oxidase 4 inhibition to trigger lipid oxidative stress, enhancing ferroptotic death of FLT3-mutant AML cells. Altogether, our study reveals a C/EBP & alpha; function in lipid homeostasis and adaptation to redox stress, and a previously unreported vulnerability of FLT3-mutant AML to ferroptosis with promising therapeutic application. SIGNIFICANCE: FLT3 mutations are found in 30% of AML cases and are actionable by tyrosine kinase inhibitors. Here, we discovered that C/EBP & alpha; regulates FA biosynthesis and protection from lipid redox stress downstream mutant-FLT3 signaling, which confers a vulnerability to ferroptosis upon FLT3 inhi-bition with therapeutic potential in AML.