SLC6A14-mediated glutamine promotes SYTL4-CXCL8 axis activation to drive gemcitabine resistance and immune evasion in pancreatic cancer.

Chemoresistance remains a major challenge in pancreatic ductal adenocarcinoma (PDAC). Glutamine sustains drug resistance and shapes the immunosuppressive tumor microenvironment; however, the underlying mechanisms remain unclear. Identifying key regulators that drive both gemcitabine resistance and immune evasion is crucial for improving theapeutic outcomes in PDAC. Here we identified solute-carrier family 6 member 14 (SLC6A14) as the central regulator of glutamine metabolism that drives gemcitabine resistance. SLC6A14-mediated glutamine metabolism facilitated α-ketoglutarate production, activating mTOR/NF-κB signaling to upregulate PD-L1 expression, playing a central role in immune evasion. Moreover, SLC6A14 induced CXC motif chemokine ligand 8 secretion via synaptotagmin-like 4-mediated exocytosis, paracrinally activating CXCR2 signaling in cancer-associated fibroblasts to enhance mitochondrial fission and amino acid recycling, supporting PDAC progression. Targeting SLC6A14 with α-methyl-tryptophan enhanced gemcitabine sensitivity, suppressed PD-L1 driven immune evasion and reduced tumor growth, metastasis and glutamine production in vivo. These findings underscore SLC6A14 as a pivtoal mediator of glutamine-driven gemcitabine resistance and immune evasion in PDAC. Therapeutic strategies targeting SLC6A14, either alone or in combination with PD-L1 blockade, hold promise for overcoming chemoresistance and enhancing antitumor immunity in gemcitabine-resistant pancreatic cancer.