Arachidonic acid analog AACOCF3 suppresses cPLA2-negative NSCLC cell proliferation by targeting SSRP1 to activate the IFNα/β pathway.

AACOCF3, a cell-permeable arachidonic acid analogue, is widely established as a selective inhibitor of cytosolic phospholipase A2 (cPLA2, PLA2G4A) in studies of metabolic disorders. Although its primary mechanism involves cPLA2 inhibition, emerging evidence indicates that AACOCF3 may target additional protein entities, exemplified by calcium-independent phospholipase A2 (iPLA2, PLA2G6) and fatty acid amide hydrolase (FAAH). Notably, cPLA2 displays a markedly heterogeneous expression profile in non-small cell lung cancer (NSCLC). Our findings establish that AACOCF3 exerts more potent growth inhibition in cPLA2-negative NSCLC cells, with IC50 values of 15.13 μM for H1975 and 15.84 μM for PC9 cells, in contrast to the cPLA2-positive A549 cells (IC50 = 56.23 μM). Mechanistically, AACOCF3 upregulates IFN-α/β signaling-associated genes (e.g., IFNB1, ISG15) specifically in cPLA2-negative NSCLC cells. This aligns with TCGA-LUAD data revealing that PLA2G4A-low tumors predominantly engage immune-activation pathways rather than metabolic programs when compared to PLA2G4A-high counterparts. Through integrated molecular docking and surface plasmon resonance (SPR) analysis, we identified structure-specific recognition protein 1 (SSRP1) as a direct molecular target of AACOCF3 in cPLA2-negative NSCLC, with SPR binding studies confirming a stable interaction (Kd = 25.9 μM). Ectopic SSRP1 expression abrogated AACOCF3-induced phenotypic alterations, concurrently suppressing IFN-α/β signaling. Collectively, these results provide evidence that AACOCF3 exerts its anti-proliferative effect by targeting SSRP1, which leads to the activation of the IFNα/β pathway, thereby underscoring its therapeutic promise for the cPLA2-negative patient subpopulation.