Targeting a novel metabolic vulnerability of non-small cell lung cancer to fatty acid oxidation surmounts chemoresistance

Aims: Non-small cell lung cancer (NSCLC) patients treated with platinum drugs develop chemoresistance. C/EBPβ has alternative translational LAP and LIP isoforms which impact cancer chemoresistance by modulating ABC efflux transporter expression and activity. Differential alternative translation of LAP:LIP reprograms metabolism in murine embryonic fibroblasts; however, little is known in cancer. To target possible metabolic vulnerabilities, we herein investigated whether LAP/LIP rewires NSCLC cell metabolism towards a chemoresistant phenotype. Methods: LAP- or LIP-overexpressing NSCLC cells were screened for anticancer drug sensitivity, DNA damage and ABC exporter expression and function. Metabolome/lipidome analyses and functional metabolic assays were performed to identify possible chemosensitizing agents. Tumor growth, mass spectrometry imaging and single-cell RNA-sequencing were determined in Hu-CD34+NSG xenografts. Results: LAP induced chemoresistance by increasing ABCB1/ABCC1/ABCC2 levels, activity and oxidative DNA damage. Furthermore, LAP altered metabolome and lipidome composition of plasma membrane and mitochondria, and upregulated HADHA and CPT1A, key enzymes in fatty acid oxidation (FAO). The high metabolic flux through FAO and oxidative phosphorylation increased mitochondrial ATP levels, thereby fueling these ATP-driven multidrug efflux pumps. Conversely, LIP displayed the opposite effect. CPT1A knock-out or catalytically-inactive mutant, FAO inhibition with etomoxir or trimetazidine, surmounted chemoresistance. In LAPhigh chemoresistant immune-xenografts, etomoxir redistributed fatty acids within tumor immune-microenvironment (TIME), metabolically reprogrammed NK cells and enhanced their anti-tumor activity. Conclusion: Increased LAP:LIP ratio induced chemoresistance in NSCLC tumors by instigating a FAO-dependence, unveiling a metabolic vulnerability. FAO inhibition emerges as a novel chemosensitization strategy operating via rewiring tumor and TIME metabolism.