Reactivation of MAPK-SOX2 pathway confers ferroptosis sensitivity in KRASG12C inhibitor resistant tumors

The clinical success of KRAS^G12C inhibitors (G12Ci) including AMG510 and MRTX849 is limited by the eventual development of acquired resistance. A novel and effective treatment to revert or target this resistance is urgent. To this end, we established G12Ci (AMG510 and MRTX849) resistant KRAS^G12C mutant cancer cell lines and screened with an FDA-approved drug library. We found the ferroptosis inducers including sorafenib and lapatinib stood out with an obvious growth inhibition in the G12Ci resistant cells. Mechanistically, the G12Ci resistant cells exhibited reactivation of MAPK signaling, which repressed SOX2-mediated expression of cystine transporter SLC7A11 and iron exporter SLC40A1. Consequently, the low intracellular GSH level but high iron content engendered hypersensitivity of these resistant tumors to ferroptosis inducers. Ectopic overexpression of SOX2 or SLC7A11 and SLC40A1 conferred resistance to ferroptosis in the G12Ci resistant cells. Ferroptosis induced by sulfasalazine (SAS) achieved obvious inhibition on the tumor growth of xenografts derived from AMG510-resistant KRAS^G12C-mutant cells. Collectively, our results suggest a novel therapeutic strategy to treat patients bearing G12Ci resistant cancers with ferroptosis inducers.