Abstract 358: Restoring necroptosis in colorectal cancer cells to overcome chemotherapeutic resistance

Abstract

Abstract Colorectal cancer (CRC) is a leading cause of cancer related deaths in the United States. CRC patients are often treated with chemotherapeutic drugs, such as 5-fluorouracil (5-FU), and resistance to chemotherapy is a major clinical problem. 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). TCGA RNA-Seq data reveal that RIP1 and RIP3 are frequently downregulated in CRC, with RIP3 downregulation correlating with worse clinical outcomes. We found that loss of RIP3 expression in CRC cells is associated with decreased 5-FU sensitivity. RIP3 silencing in CRC was shown to be caused by promoter hypermethylation. However, the exact functional role of RIP3 in response to anticancer therapies remains unclear. Our studies reveal that RIP3-expressing CRC cells were able to undergo both apoptosis and necroptosis in response to 5-FU treatment, which was abrogated upon knock-out or inhibition of RIP3. Restoration of RIP3 in RIP3-silenced CRC cells by transfection enhanced 5-FU sensitivity, along with restored necroptosis and enhanced apoptosis. Furthermore, we have shown that RIP3 expression can be restored in RIP3-silenced CRC cells by the DNA methyltransferase 1 inhibitor 5-aza-2’-deoxycytidine (5-aza-dC), which also enhances 5-FU sensitivity. This effect of 5-aza-dC is partially dependent on RIP3 and suppressed by a RIP3 inhibitor. Together, our results suggest RIP3 plays a critical role in response to 5-FU and other chemotherapeutic agents, and that restoring RIP3 expression can be used to potentiate chemotherapy. These results provide novel insight into the functional role of RIP3 in CRC chemotherapy, which could be explored for developing improved and personalized CRC treatments based on RIP3 status. Citation Format: Kaylee Ermine, Dongshi Chen, Peng Wang, Jian Yu, Lin Zhang. Restoring necroptosis in colorectal cancer cells to overcome chemotherapeutic resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 358.