Abstract 2534: Targeting defective necroptosis in colorectal cancer to overcome therapeutic resistance

Abstract Colorectal cancer (CRC) is a leading cause of cancer related deaths in the United States. CRC patients are often treated with the chemotherapeutic drug 5-fluorouracil (5-FU), but resistance often occurs. It is well-established that 5-FU induces apoptosis in cancer cells, but apoptosis inhibition does not block the anticancer effect of 5-FU, suggesting a role of non-apoptotic cell death. Necroptosis is a regulated form of necrosis controlled by Receptor-Interacting Protein kinase 1 (RIP1), RIP3, and Mixed Lineage Kinase domain-Like (MLKL), and its role in anticancer therapy remains unclear. TCGA RNAseq data show that RIP3 is significantly downregulated in primary CRC tumors, which is correlated with worse outcomes. RIP3 downregulation also occurs in established CRC cell lines and is associated with decreased 5-FU sensitivity. Therefore, we hypothesize that necroptosis may play a critical role in anticancer therapy and that restoring defective necroptosis may enhance therapeutic sensitivity. Our studies show that RIP3-expressing (RIP3+) CRC cells undergo both apoptosis and necroptosis in response to 5-FU. As expected, knock-out of RIP3 in RIP3+ CRC cells resulted in decreased 5-FU sensitivity, as well as abrogated necroptosis induction. Additionally, stable restoration of RIP3 in RIP3-silenced (RIP3-) CRC cells appeared to enhance 5-FU response, under conditions where apoptosis was inhibited. Furthermore, we explored alternative ways to induce necroptosis in RIP3-silenced cells. Together, our results suggest that necroptosis plays an important role in 5-FU-induced cell death in CRC. These results provide novel insights into the role of necroptosis in anticancer therapy in CRC, which could be used for development of improved therapies and personalized medicine based on RIP3 status. Citation Format: Kaylee Ermine, Dongshi Chen, Xinyan Lu, Jian Yu, Lin Zhang. Targeting defective necroptosis in colorectal cancer to overcome therapeutic resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2534.