Abstract 278: System xc- inhibition shares features of necroptosis and ferroptosis in hepatocellular carcinoma cells

Abstract

Ferroptosis is characterized by iron-dependent non-apoptotic cell death involving the accumulation of lipid peroxides. Inhibition of system xc- which uptake L-cystine with the exchange of L-glutamate decreases glutathione synthesis, leading to ferroptosis. However, molecular interplay between ferroptosis and necroptosis has not been clearly identified. In this study, we investigated molecular process for cell death by SLC7A11 inhibition in hepatocellular carcinoma cell lines. The sensitivity for SLC7A11 inhibition by sulfasalazine was in the order of HepG2, Huh7 and Huh6, and then PLC/PRF/5. The decrease of cell viability by sulfasalazine and erastin was prevented by co-treatment of β-mercaptoethanol in all kinds of cell lines, indicating that the limited supply of L-cystine may contribute to cell death. Both ferrostatin and necrostatin, an inhibitor of ferroptosis and necroptosis, respectively, rescued sulfasalazine-induced growth inhibition by 60% in Huh7 and Huh6 and by 20% in HepG2. However, they failed to restore cell survival in PLC/PRF/5 cells. Sulfasalazine at the dose inducing equivalent level of cell death significantly increased lipid peroxidation in Huh7 and Huh6, but not in HepG2 and PLC/PRF/5 cells, as determined by C11-BODIPY dye. RIPK activation in necroptosis pathway by sulfasalazine was monitored in these cell lines. These results suggest that SLC7A11 inhibition triggers mixed-type of cell death via ferroptosis and necroptosis in a context-dependent manner in hepatocellular carcinoma cells (MD Abdullah and DH Kim are equally contributed to this work). Citation Format: Md Abdullah, Do Hyung Kim, Seung Jin Lee. System xc- inhibition shares features of necroptosis and ferroptosis in hepatocellular carcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 278.