Peroxiredoxin 6 Silencing Remodels Lipid Metabolism and Redox Pathways to Promote Ferroptosis-Mediated Radiosensitization in Nonsmall Cell Lung Cancer.

Ionizing radiation (IR) induces oxidative stress and lipid peroxidation with ferroptosis contributing to radiation-induced cancer cell death. Peroxiredoxin 6 (PRDX6), a multifunctional enzyme involved in phospholipid repair and redox regulation, has been implicated in ferroptosis regulation, but its role in the radiosensitivity of cancer cells remains unclear. Here, we show that PRDX6 depletion enhances radiosensitivity in A549 lung cancer cells. PRDX6-silenced A549 cells exhibited elevated lipid peroxidation and labile iron levels, indicating a ferroptosis-prone state that was amplified by radiation. To identify the underlying drivers of ferroptosis sensitivity in the PRDX6 background, we performed global proteomic profiling of PRDX6-silenced A549 cells, with and without radiation. Basal PRDX6-deficient cells displayed increased levels of ACSL4 and DHCR7. ACSL4 activates peroxidation-prone polyunsaturated fatty acids for incorporation into membrane phospholipids, and DHCR7 depletes the antiferroptotic moiety, 7-dehydrocholesterol. MPST, an antioxidant protein, was downregulated. These changes were accentuated upon IR exposure with further suppression of GINS4, a negative regulator of ferroptosis. Functional rescue by oleic acid suggested the role of ACSL4 in the observed phenotypes. Radiosensitization via ferroptosis induction was additionally demonstrated in another human lung cancer cell line under the PRDX6-silenced state. Collectively, PRDX6 loss remodels the cellular proteome to establish a presensitized redox and lipid compositional state, which favors ferroptosis-driven radiosensitivity.