Abstract 672: Small molecule NSC59984 stimulates mitochondria-dependent ferroptosis and overcomes integrated stress response pro-survival signaling in pre-clinical pancreatic and colorectal cancer models

Abstract Pancreatic and colorectal cancer are leading causes of cancer deaths worldwide. Resistance to current therapeutics is a significant challenge in treating these cancers. Ferroptosis, a non-apoptotic iron-dependent form of cell death characterized by overwhelming lipid peroxidation, has emerged as a potential strategy to overcome drug resistance. Our lab previously identified the small-molecule NSC59984 as a p53 pathway restoring compound that induces reactive oxygen species, requires p73, and targets mutant p53 for ubiquitin-mediated proteolysis involving MDM2 and HSP90. In pre-clinical models of pancreatic and colorectal cancer, we now show that the small-molecule NSC59984 induces lipid peroxidation and causes reactive oxygen species-dependent apoptosis as monotherapy. However, when combined with ferroptosis inducers or cystine deprivation, NSC59984 potently induces ferroptosis in a mitochondrial complex III-dependent manner. Using CRISPR/Cas9 in pancreatic cancer cells, we further show that HRI, an EIF2-alpha kinase responsible for the cellular response to mitochondrial stress, induces the integrated stress response (ISR) upon treatment with NSC59984 or ferroptosis inducers. The ISR serves as a mechanism for resistance to cell death induced by NSC59984 or ferroptosis inducers, causing upregulation of key anti-oxidative stress and anti-ferroptosis proteins, including the cystine importer SLC7A11 and the GPX4-stabilizing protein HSPA5/BIP/GRP78. The combination therapy overcomes the ISR to induce potent cell death. Our work demonstrates the importance of the interplay between mitochondria and the ISR during ferroptosis induction in pancreatic and colorectal cancer cells. Citation Format: Praveen R. Srinivasan, Arielle J. De La Cruz, Maximilian Pinho-Schwermann, Andrew George, William J. MacDonald, Shengliang Zhang, Wafik S. El-Deiry. Small molecule NSC59984 stimulates mitochondria-dependent ferroptosis and overcomes integrated stress response pro-survival signaling in pre-clinical pancreatic and colorectal cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 672.