Ferumoxytol potentiates ferroptotic radiosensitization through NCOA4-associated iron mobilization in brain-metastatic lung cancer cells

Brain metastasis remains a major cause of mortality in patients with advanced non-small cell lung cancer, whereas effective radiosensitization strategies are constrained by heterogeneous tumor responses and the tolerance of normal brain tissue. Ferumoxytol, a clinically used iron oxide nanoparticle formulation, has emerging translational potential as an iron-modulating agent. However, whether Ferumoxytol enhances radiosensitivity in brain-metastatic lung cancer cells and the mechanisms underlying this effect remain unclear.

PC-9 lung adenocarcinoma cells and NCI-H1915 brain-metastatic lung adenocarcinoma cells were used to evaluate ferumoxytol under basal and irradiated conditions. Ferroptosis-associated phenotypes, oxidative stress, clonogenic survival, and cell-cycle distribution were assessed. TMT-based proteomics and public single-cell and spatial transcriptomic analyses were used for candidate prioritization and disease-context support. NCOA4 was evaluated by siRNA-mediated loss of function, single-dose clonogenic assays, time-resolved NCOA4/FTH1 immunoblotting, bafilomycin A1-based autophagic-flux analysis, and endogenous NCOA4-FTH1 co-immunoprecipitation.

Ferumoxytol induced mitochondrial, biochemical, and molecular changes consistent with ferroptosis and enhanced irradiation-associated ROS accumulation, lipid peroxidation, and loss of clonogenic survival. Proteomic analysis prioritized NCOA4, while public transcriptomic analyses provided associative disease-context support. In H1915 cells, NCOA4 silencing attenuated combined-treatment Fe²⁺ accumulation, oxidative stress, and γ-H2AX induction. The incremental reduction in colony formation produced by adding ferumoxytol to irradiation was also reduced after NCOA4 knockdown in H1915 cells and was no longer significant in PC-9 cells. Time-resolved immunoblotting showed marked FTH1 accumulation rather than net FTH1 depletion, with a late reduction in NCOA4. Bafilomycin A1 caused further LC3B-II and SQSTM1/p62 accumulation under IR + F, consistent with ongoing autophagic turnover, whereas co-immunoprecipitation showed greater normalized recovery of FTH1 in NCOA4 immunoprecipitates after IR + F.

Ferumoxytol enhances ferroptosis-associated oxidative injury and radiosensitivity in the tested lung cancer cell models. The combined loss-of-function, autophagic-flux, and protein-interaction data support the involvement of NCOA4-associated ferritin handling and iron mobilization. However, the observed FTH1 accumulation and the absence of iron-chelator rescue, cargo-specific lysosomal tracking, and in vivo validation preclude a definitive claim of canonical ferritinophagy or clinical efficacy.