Resistance to sorafenib, a frontline therapy for advanced ccRCC, is linked to the decreased sensitivity to ferroptosis. Our research is focus on elucidating the mechanisms behind ccRCC’s resistance to sorafenib-induced ferroptosis and on identifying new potential agents that could overcome the resistance.

The silencing of SREBP1 was utilized to evaluate the role of this key transcript factor for lipid synthesis in the ferroptosis resistance of ccRCC cells induced by sorafenib. ATF4 mediated induction of SREBP1 upon the administration of Salinomycin was assessed using western blot, RT-PCR, immunohistochemistry staining, chromatin immune-precipitation and dual-luciferase report assay. In cultured ccRCC cells, the combined impact of salinomycin and sorafenib on ferroptosis induction was assessed by evaluating cell viability, glutathione levels, malondialdehydelevels, BODIPY fluorescence and intracellular Fe2+ concentration. In an orthotopic ccRCC mouse model, the synergistic effect of salinomycin and sorafenib on both ferroptosis and tumor progression was examined.

Overexpression of SREBP1 was found in ccRCC tumor tissue, and induced by sorafenib administration. Silencing SREBP1 reduced the resistance of ccRCC cells to ferroptosis induced by sorafenib. Salinomycin reduced ATF4 level, which in turn inhibited Srebp1 transcription. Treatment of salinomycin enhanced the sensitivity ccRCC cells to sorafenib-induced ferroptosis. In an orthotopic xenograft mouse model of ccRCC, combination of salinomycin and sorafenib demonstrated a synergistic effect in inducing ferroptosis inhibiting tumor growth.

Salinomycin treatment mitigates resistance to sorafenib-induced ferroptosis by inhibiting SREBP1. The combined use of salinomycin and sorafenib synergistically boosts ferroptosis and curbs the growth of ccRCC.