Abstract
Cuproptosis is a recently discovered form of regulated cell death triggered by mitochondrial copper accumulation and proteotoxic stress. Here, we provide the first evidence that glutathione (GSH), a major non-protein thiol in cells, acts as a cuproptosis inhibitor in pancreatic ductal adenocarcinoma (PDAC) cells. Mechanistically, GSH inhibits cuproptosis by chelating copper, contrasting its role in blocking ferroptosis by inhibiting lipid peroxidation. The classical cuproptosis inducer, ES-Cu (elesclomol plus copper), increases the protein stability of the transcription factor NFE2L2 (also known as NRF2), leading to the upregulation of gene expression of glutamate-cysteine ligase modifier subunit (GCLM) and glutamate-cysteine ligase catalytic subunit (GCLC). GCLM and GCLC are rate-limiting enzymes in GSH synthesis, and increased GSH is transported into mitochondria via the solute carrier family 25 member 39 (SLC25A39) transporter. Consequently, genetic inhibition of the NFE2L2-GSH-SLC25A39 pathway enhances cuproptosis-mediated tumor suppression in cell culture and in mouse tumor models. These findings not only reveal distinct mechanisms of GSH in inhibiting cuproptosis and ferroptosis, but also suggest a potential combination strategy to suppress PDAC tumor growth.