One-carbon metabolic reprogramming and its relationship with tumor-infiltrating lymphocytes and Immune checkpoint in Pancreatic cancer

BACKGROUND The role of oncogene-driven metabolic reprogramming in pancreatic cancer (PC) remains unclear. This study explored the interplay between one-carbon metabolism (OCM), driver genes, and the tumor microenvironment (TME) in PC. METHODS Targeted metabolomics analyzed 136 PC serum samples. Transcriptomic and OCM gene data from 930 PC patients were obtained from public databases. Non-negative matrix factorization (NMF) clustering classified metabolic subtypes. Single-cell analysis deciphered OCM features in the TME. Immunohistochemistry assessed MTHFD1L expression, cancer-associated fibroblast (CAF) markers (FAP, α-SMA), immune cells (CD8+/Foxp3+ TILs, CD206+ TAMs), and PD-1/PD-L1 in 138 tissue samples. RESULTS Targeted metabolomics identified altered amino acid metabolism (73 metabolites). NMF clustering stratified patients into C1/C2 subtypes with distinct prognoses and TME characteristics (p<0.05). Single-cell analysis revealed OCM dysregulation in cancer cells, macrophages, and fibroblasts. MTHFD1L emerged as a core driver of metabolic reprogramming, correlating with poor overall survival (OS, p=0.005) and disease-free survival (DFS, p=0.006). High MTHFD1L expression was linked to lymph node metastasis and positively associated with FAP in CAFs (p<0.05), CD206+ TAMs (p<0.001), and Foxp3+ TIL infiltration (p<0.05). Multivariate analysis confirmed MTHFD1L as an independent prognostic factor (p=0.022). CONCLUSION OCM reprogramming is a hallmark of PC. MTHFD1L drives oncogenic metabolism and influences prognosis by modulating CAFs, TAMs, and Tregs. Targeting OCM or MTHFD1L may offer therapeutic potential.