Ferroptosis induction induced by ginkgetin enhances therapeutic  effect of cisplatin in EGFR wild type non-small cell lung cancer

Abstract

Background Cisplatin (DDP) is the first-in-class drug for advanced and non-targetable non-small cell lung cancer (NSCLC). Recent study indicates that DDP could slightly induce non apoptotic cell death ferroptosis, and the cytotoxicity was promoted by ferroptosis inducer. The agents enhancing ferroptosis level therefore may increase anticancer effect of DDP. Several lines of evidence support the usage of phytochemicals in therapy of NSCLC. Ginkgetin, a bioflavonoid derived from Ginkgo biloba leaves, showed anti-cancer effect on NSCLC both in vitro and in vivo, which could strongly trigger autophagy. Ferroptosis can be triggered by autophagy, and which regulates redox homeostasis. Thus, we aim to elucidate the possible role of ferroptosis induction in accounting for synergy of ginkgetin with DDP in cancer therapy.Methods Ginkgetin promoted DDP-induced anticancer effect was observed via cytotoxicity assay and western blot. Ferroptosis triggered by ginkgetin in DDP treated NSCLC was observed via lipid peroxidation assay, labile iron pool assay, western blot, and QPCR. With ferroptosis blocking, the contribution of ferroptosis on ginkgetin + DDP induced cytotoxicity, Nrf2/HO-1 axis and apoptosis were determined via luciferase assay, immunostaining, chromatin immunoprecipitation (CHIP), and flow cytometry. The role of ferroptosis in ginkgetin + DDP treated NSCLC cells was illustrated by the application of ferroptosis inhibitor, which was further demonstrated in xenograft nude mice model.Results Ginkgetin synergized cisplatin in cytotoxicity in NSCLC cells, which concomitant with increased labile iron pool and lipid peroxidation: both these processes were the key characteristics of ferroptosis. The induction of ferroptosis, mediated by ginkgetin, was further confirmed by decline expressions of SLC7A11, GPX4 and GSH/GSSG ratio. In parallel, ginkgetin disrupted redox hemeostasis in DDP-treated cells, demonstrated by the enhanced ROS formation and inactivation on Nrf2/HO-1 axis. Ginkgetin also enhanced DDP-induced mitochondrial membrane potential (MMP) loss and apoptosis in cultured NSCLC cells. Furthermore, blocking ferroptosis reversed the gingketin-induced inactivation on Nrf2/HO-1, as well as the elevation on ROS formation, MMP loss and apoptosis in DDP-treated NSCLC cells.Conclusion This study firstly reported that ginkgetin promoted DDP-induced anticancer effect, which could be accounted by induction of ferroptosis.