Ferritin Light Chain: A Key Regulator of Nrf2-Dependent Ferroptosis in Oral Squamous Cell Carcinoma

Objective Nuclear factor erythroid 2-related factor 2 (Nrf2) is a critical regulator of ferroptosis, and ferritin light chain (FTL) plays a central role in iron metabolism and is actively involved in the ferroptotic process. However, the mechanism by which Nrf2 may modulate ferroptosis in oral squamous cell carcinoma (OSCC) through the regulation of FTL remains poorly understood. This study aims to investigate the molecular mechanisms underlying Nrf2-mediated regulation of ferroptosis via FTL in OSCC cell lines SCC-25 and CAL-27, with the goal of providing new insights into the ferroptosis regulatory network in OSCC. Methods The expression profiles of Nrf2 and FTL were initially characterized in OSCC tissues and matched adjacent normal tissues, with subsequent correlation analysis against clinicopathological parameters. To investigate their functional roles, Nrf2 and FTL expression was silenced using siRNA technology in combination with ferroptosis inhibitor Fer-1 treatment. Cellular viability was determined by CCK-8 assay, while Ferroptosis was assessed by measuring intracellular Fe²⁺ concentrations and MDA content. Quantitative assessment of lipid peroxidation was performed with flow cytometry. Protein expression patterns of Nrf2, FTL, and downstream ferroptosis regulators (GPX4, FSP1, and ACSL4) were analyzed by Western blot. The regulatory function of the Nrf2-FTL axis in ferroptosis was further validated through complementary gene knockdown and overexpression experiments. Results Molecular analyses demonstrated significant upregulation of Nrf2 and FTL expression in both OSCC tissues and cell lines, with Nrf2 expression levels showing strong correlation with lymph node metastasis and advanced T-stage (T3-T4a). Functional investigations revealed that Nrf2 maintains its expression through a positive feedback loop while transcriptionally activating FTL, establishing a critical "Nrf2-FTL-iron metabolism" regulatory axis. Genetic silencing experiments demonstrated that knockdown of either Nrf2 or FTL synergistically reduced cell viability, induced iron accumulation, increased lipid peroxidation, and altered ferroptosis-related protein expression - effects that were partially rescued by the ferroptosis inhibitor Fer-1. Mechanistically, this regulatory axis suppresses ferroptosis susceptibility by coordinately maintaining iron homeostasis and redox balance. Notably, Nrf2 overexpression could counteract the enhanced ferroptosis resulting from FTL knockdown, unequivocally establishing the central role of the Nrf2-FTL axis in regulating ferroptosis in OSCC. Conclusion The Nrf2-FTL axis maintains its expression level through a positive feedback regulatory mechanism and modulates iron metabolism and oxidative stress pathways, thereby inhibiting ferroptosis susceptibility in OSCC cells.