Target FADS1-arachidonic acid-ferroptosis axis: A metabolic bridge linking matrix stiffness to PDAC stemness

The elevated stiffness of extracellular matrix (ECM), one of the typical physical hallmarks of pancreatic ductal adenocarcinoma (PDAC), which was proved to promote stemness and leads to adverse prognosis. Therefore, to dissect the underlying mechanisms between matrix stiffness and stemness is important. To this end, stiffness tunable hydrogel based on polyacrylamide (PA) was employed to simulate the stiffness of PDAC microenvironment. Our results illustrated that stiff matrix enhanced PDAC (MIA PaCa-2 and PANC-1 cells) stemness by inhibiting ferroptosis. Lipidomic analyses further revealed that matrix stiffness reprogrammed medium and long chain fatty acid metabolism, with particularly prominent arachidonic acid (AA) depletion. Intriguingly, AA supplementation restored ferroptosis sensitivity and reversed stiffness-induced stemness enhancement. Mechanistically, matrix stiffness inhibits AA content by downregulating FADS1 (fatty acid desaturase 1), a key biosynthesis enzyme. Simultaneously, the ferroptosis was suppressed accompanied by the AA reduction, which was validated via decreased lipid peroxidation and preserved mitochondrial morphology. Besides, FADS1 knockdown recapitulated the stiff matrix effects, causing ferroptosis inhibition and stemness enhancement, which could be rescued by AA supplementation. Collectively, our data shed light on the novel mechanism: matrix stiffness-suppressed FADS1 drives AA-replied ferroptosis inhibition, ultimately promoting PDAC stemness. Targeting the FADS1-AA-ferroptosis axis may provide practicable opportunities for the therapy of PDAC.