Although apoptosis has been thought as the principal mechanism of programed cell death in chemotherapy, other forms of non-apoptotic death also has been noted. The oncogenic RAS-selective lethal small molecule erastin triggers a unique iron-dependent form of cell death termed ferroptosis. This mechanism is expected to induce eradication of chemotherapeutic (e.g. platinum) resistant cancer cells. In this study we demonstrate this new form of cell death in ovarian cancer cells. The clear cell epithelial ovarian cancer cell lines, TOV-21G (KRAS_G13C) and KOC-7C (RAS wild type) were used in this study. Erastin dose-dependently inhibited growth in TOV-21G cells, but not KOC-7C cells. Treatment of TOV-21G cells with erastin resulted in increase of ROS. Iron chelator deferoxamine (DFO) rescued growth inhibition induced by erastin in TOV-21G cells. Although cisplatin inhibited growth in TOV-21G cells, this inhibition was not rescued by DFO. The GSH level was reduced by erastin, but this reduction was not rescued by DFO. In addition, the basal GSH level was higher and the basal ROS level was lower in KOC-7C cells than those in TOV-21G cells. Erastin induced ferroptosis by reducing the GSH level in RAS mutant ovarian cancer cells. Although DFO rescued growth inhibition induced by erastin, the pathway was not on System Xc-. The sensitivity to erastin might depends on the basal level of GSH in cells. Ferroptosis had great potential to become a new approach in anti-tumor therapies in ovarian cancer.

Citation Format: Motoki Takenaka, Noriko Suzuki, Minako Mori, Hitomi Aoki, Tasuku Hirayama, Hideko Nagasawa, Ken-ichirou Morishige. Ferroptosis induced by erastin in RAS mutant ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2322.