Tumor-associated Schwann cell remodeling under metabolic stress via lactate sensing orchestrates pancreatic ductal adenocarcinoma development.

Diabetes mellitus (DM) is a known risk factor for pancreatic cancer, but the underlying mechanisms remain elusive. Here, we identify lactate-driven remodeling of tumor-associated Schwann cells (TASCs) as a key mediator of immunosuppression in diabetic pancreatic ductal adenocarcinoma (PDAC). Single-cell RNA sequencing revealed a c1-Mettl16+Cd276+Nectin2+ TASC subpopulation enriched in diabetic tumors that impairs CD8+ T cell function and promotes PD-1 resistance. Mechanistically, lactate enters TASCs via MCT1/MCT4, binds METTL16, and induces K269 lactylation, enhancing m6A-dependent CTCF stabilization and transcriptional activation of immunosuppressive ligands. Targeting METTL16 restores immune surveillance and sensitizes tumors to PD-1 blockade. Retrospective analyses confirmed therapeutic benefit in patients with diabetic PDAC receiving rosuvastatin. These findings uncover a lactate-METTL16-CTCF axis that links metabolic stress to epitranscriptomic reprogramming and immune evasion, offering a promising strategy to potentiate immunotherapy in metabolically dysregulated PDAC.