DHODH inhibition drives albumin-mediated drug resistance through TERF2IP lactylation-activated macropinosome-mitochondria contact.

Macropinocytosis enables cancer cells to scavenge extracellular nutrients and contributes to tumor progression, but its role in chemoresistance remains poorly characterized. Through CRISPR-Cas9 and small-molecule screens, we identify inhibition of dihydroorotate dehydrogenase (DHODH), an enzyme in pyrimidine synthesis, as an inducer of macropinocytosis. Mechanistically, DHODH inhibition triggers metabolic reprogramming toward glycolysis and lactate accumulation. This metabolic shift promotes lysine 208 lactylation of telomeric repeat-binding factor 2-interacting protein (TERF2IP), unveiling its moonlighting function in transcriptional activation of epiregulin, which activates EGFR signaling to promote macropinocytosis. Macropinosomes contact mitochondria, enabling albumin translocation into the mitochondrial intermembrane space where it interacts with DHODH, diminishing inhibitor binding and restoring DHODH activity. This adaptive response contributes to drug resistance in vitro and in vivo, and co-administration of DHODH inhibitors with macropinocytosis blockers or EGFR inhibitors enhances anti-tumor efficacy. Our findings reveal a previously unknown metabolic stress-induced macropinocytosis pathway and provide a rationale for combination therapy to enhance DHODH inhibitor efficacy in cancer treatment.