Restricting lipid accumulation in tumor-infiltrating neutrophils mediates caloric restriction-induced anti-cancer...

Caloric restriction (CR) induces tumor resistance in mammals, but its mechanisms remain poorly understood. Here, we found that CR altered the proportions and gene expression profiles of tumor-infiltrating neutrophils (TINs). Depletion of neutrophils largely abrogated CR-induced tumor inhibition across multiple murine cancer models, underscoring their critical role in CR's broad anti-tumor effect. CR-induced gene expression changes in TINs were associated primarily with lipid-related processes, notably downregulating hypoxia-inducible lipid droplet-associated (HILPDA). This downregulation reduced lipid accumulation in TINs, limiting tumor growth and enhancing anti-tumor immunity by decreasing lipid transfer to tumor and immune effector cells. Upstream, CR reduced hypoxia-inducible factor 1 (HIF-1α) mRNA expression in circulating neutrophils by decreasing insulin-like growth factor 1 (IGF-1), thereby limiting HILPDA expression in TINs. Patients with lung cancer who had low baseline neutrophil HIF-1α mRNA exhibited improved responses to combined immunotherapy. These findings identify a novel neutrophil- and lipid-centered mechanism for CR-induced tumor inhibition, suggesting the IGF-1/HIF-1α/HILPDA axis as a therapeutic target.