Autophagic degradation of RAB8A promotes ferroptosis through dysregulation of TFRC-mediated iron uptake

Ferroptosis is an iron-dependent form of regulated cell death driven by lipid peroxidation; however, how selective autophagy regulates ferroptotic sensitivity remains incompletely understood. Here, we identify RAB8A as a selective autophagic substrate and negative regulator of ferroptosis. Quantitative proteomic analyses reveal that ferroptotic stress induces ATG5- and ATG7-dependent degradation of RAB8A. Mechanistically, ferroptotic stimuli induce RNF126-dependent polyubiquitination of RAB8A and subsequent SQSTM1-mediated autophagic degradation. Functionally, loss of RAB8A sensitizes cancer cells to ferroptosis, whereas expression of the degradation-resistant active mutant RAB8AQ67L suppresses ferroptotic cell death. RAB8A interacts with TFRC and facilitates stress-induced redistribution of TFRC from the plasma membrane toward endolysosomal compartments. RAB8A deficiency impairs TFRC clearance, enhances transferrin-dependent iron uptake, and increases intracellular Fe²⁺ accumulation and lipid peroxidation. In fibrosarcoma and pancreatic cancer xenograft models, RAB8A depletion enhances the antitumor efficacy of ferroptosis-inducing therapy. Clinically, RAB8A is upregulated and associated with poor prognosis and ferroptosis resistance in pancreatic cancer. Collectively, these findings establish an autophagy-RAB8A-TFRC axis that regulates ferroptotic sensitivity.Abbreviations: BCA: bicinchoninic acid; BSA: bovine serum albumin; CCK-8: cellcounting kit-8; Co-IP: co-immunoprecipitation; DMSO: dimethylsulfoxide; ELISA: enzyme-linked immunosorbent assay; FBS: fetalbovine serum; HRP: horseradish peroxidase; IP: immunoprecipitation;LC-MS/MS: liquid chromatography-tandem mass spectrometry; MDA:malondialdehyde; MEF: mouse embryonic fibroblast; PBS:phosphate-buffered saline; PBS-T: PBS containing Tween-20; PI:propidium iodide; PVDF: polyvinylidene difluoride; qPCR: quantitativereal-time polymerase chain reaction; SDS: sodium dodecyl sulfate;STR: short tandem repeat; TBA: thiobarbituric acid; TBST:Tris-buffered saline containing Tween-20; TMT: tandem mass tag; WT:wild type.