Abstract 3575: Ferroptosis: A novel nonapoptotic cell death overcomes head and neck cancer resistance to cisplatin

Abstract

Abstract Ferroptosis was recently identified as a novel form of iron-dependent cell death different from apoptosis or necrosis. Inhibition of key molecules related to ferroptosis, cystine-glutamate antiporter (xCT) and glutathione peroxidase (GPX4), may induce the eradication of cancer cells resistant to conventional chemotherapy or radiotherapy. The present study investigated whether ferroptosis overcome head and neck cancer (HNC) resistant to cisplatin treatment. Three cisplatin-resistant HNC cell lines (AMC-HN3R, -HN4R and -HN9R), their parental lines, and other human HNC lines were used. The effects of cysteine and glutamate alteration and pharmacological and genetic inhibition of xCT were assess by measuring viability, death, total and cytoplasmic lipid reactive oxygen species (ROS) production, mitochondrial membrane potential (ΔΨm), protein expression, and preclinical mouse tumor xenograft models. Conditioned media with no cysteine or high glutamate supplement induced ferroptosis of both cisplatin-sensitive and -resistant HNC cells without apparent change of necrosis and apoptosis markers, RIP1 and RIP3 and casplase-3 expression, and ΔΨm. This was blocked by antioxidants trolox or N-acetyl cysteine pretreatment. Sulfasalazine, artensunate, and erastin inhibited the growth of HNC cells and accumulated cytoplasmic lipid ROS via induction of ferroptosis and inhibition of xCT protein expression. Genetic silencing of xCT with siRNA or shRNA treatment also induced the effective cell death (ferroptosis) of resistant HNC cells. These effects were blocked with trolox or ferrostatin-1 pretreatment. Pharmacological and genetic inhibition of xCT significantly sensitized resistant HNC cells to cisplatin in vitro and in vivo. Cystine deficiency or glutamate excess induces ferroptosis in HNC cells. Further, pharmacological and genetic inhibition of xCT overcomes the cisplatin resistance of HNC cells by inducing ferroptosis. Citation Format: Hye Jin Jang, Jin Young Park, Eun Hye Kim, Ji Won Kim, Minsu Kwon, Jong-Lyel Roh. Ferroptosis: A novel nonapoptotic cell death overcomes head and neck cancer resistance to cisplatin. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3575.