Sarcosine sensitizes lung adenocarcinoma to chemotherapy by dual activation of ferroptosis via PDK4/PDHA1 signaling and NMDAR-mediated iron export

Abstract

Abstract Background Ferroptosis, a regulated cell death driven by iron-dependent lipid peroxidation, is associated with chemoresistance in lung adenocarcinoma (LUAD). This study aims to investigate the role of sarcosine in ferroptosis and its underlying mechanisms. Methods An RSL3-induced ferroptosis model was used to screen a library of 889 human endogenous metabolites and metabolomic profiling was harnessed to identify metabolites associated with ferroptosis. Cell viability, lipid-reactive oxygen species (ROS), ferrous iron, malondialdehyde (MDA), and mitochondrial integrity were assessed to evaluate sarcosine’s effects on ferroptosis. Metabolic fate was studied using 15 N-labeled sarcosine. Next, we used untargeted metabolomic profiling and next-generation sequencing to dissect metabolic and transcriptomic changes upon sarcosine supplementation. The effects of sarcosine on ferroptosis and chemotherapy were further validated in patient-derived organoids (PDOs), xenograft models, and LUAD tissues. Results Sarcosine emerged as a potent ferroptosis inducer in the metabolic library screening, which was further confirmed via cell viability, lipid-ROS, ferrous iron, and MDA measurements. Metabolic flux analysis showed limited conversion of sarcosine to other metabolites in LUAD cells, while untargeted metabolomic profiling and seahorse assays indicated a metabolic shift from glycolysis to oxidative phosphorylation. Sarcosine enhanced pyruvate dehydrogenase activity to generate more ROS by interacting with PDK4, reducing PDHA1 phosphorylation. As a co-activator of N-methyl-D-aspartate receptor (NMDAR), sarcosine also exerted its pro-ferroptosis effect via regulating ferrous export through the NMDAR/MXD3/SLC40A1 axis. Given the significance of ferroptosis in chemotherapy, we validated that sarcosine enhanced the sensitization of cisplatin by promoting ferroptosis in LUAD cells, PDOs, and xenograft models. Conclusion Sarcosine promotes ferroptosis and enhances chemosensitivity, suggesting its potential as a therapeutic agent in treating LUAD.