Acute Exposure to Cadmium Triggers NCOA4-Mediated Ferritinophagy and Ferroptosis in Never-Smokers Oral Cancer Cells

Cadmium (Cd), a carcinogenic component of tobacco, is a recognized risk factor for oral squamous cell carcinoma (OSCC). However, the molecular mechanisms underlying Cd-induced cytotoxicity in OSCC remain largely undefined. Here, we demonstrate that acute Cd exposure triggers ferroptosis in CAL27 OSCC cells derived from never-smokers, but not in SCC154 cells derived from smokers. Mechanistically, Cd outcompetes Fe, causing early iron depletion and activating the nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy. This process enhances the labile iron pool, promotes mitochondrial reactive oxygen species (ROS) generation, lipid peroxidation, and ferroptotic cell death. Notably, iron supplementation rescues CAL27 cells from Cd-induced damage, while exacerbating iron deficiency through transferrin receptor CD71 silencing amplifies cytotoxicity. Conversely, OSCC cells from smokers exhibit resistance to Cd toxicity, likely due to the overexpression of metallothionein 2A (MT2A), a heavy metal detoxification protein. Collectively, this study provides the evidence that ferritinophagy may act as a critical upstream driver of Cd-induced ferroptosis in OSCC cells derived from never-smokers, paving the way for potential ferroptosis-targeted therapeutic strategies in Cd-associated malignancies.