Abstract 707: Emerging role of mitochondrial pathway in crosstalk between ferroptosis and apoptosis

Abstract

Abstract Introduction: Several processes lead to cell death; ferroptosis, apoptosis, necrosis, and autophagy are the primary mechanisms. Each type of biological death has been believed to have a distinct biochemical and morphological fingerprint. However, emerging evidence suggests that these different types of cell death often share common pathways. In this study, we investigated whether mitochondrial signaling pathways play an important role in the intracellular communication between ferroptosis and apoptosis. Methods: The human colorectal carcinoma HCT116 cell line was used to evaluate the interplay between cell death pathways. Cells were treated with the apoptotic agent TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) and ferroptotic agents such as artesunate and erastin. Cell death was determined by trypan blue exclusion assay. Apoptosis was measured by western blot. Ferroptosis was assessed using MDA assay. Bax oligomerization was performed by mitochondrial fractionation followed by SDS-PAGE under nondenaturing conditions. Results: We observed that the combinatorial treatment induced synergistic apoptosis, which was mediated through an increase in caspase activation. We also observed an increase in pro-apoptotic Bax oligomerization in the mitochondrial fraction. The combined treatment-induced apoptosis was suppressed in Bax-deficient HCT116 cells. Ferroptotic agents enhanced the intracellular level of anti-apoptotic Mcl-1. However, the combined treatment decreased the level of Mcl-1. Interestingly, the combined treatment-induced apoptosis was abolished in HCT116 cells with knockin of Mcl-1 phosphorylation site mutant (S121A/E125A/S159A/T163A). Conclusions: These data suggest a novel mechanism for the combined treatment of the apoptotic agent TRAIL and ferroptotic agent erastin/artesunate-induced synergistic apoptosis through the mitochondrial pathway. Citation Format: Yong J. Lee. Emerging role of mitochondrial pathway in crosstalk between ferroptosis and apoptosis [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 707.