Abstract A015: Targeting necroptosis and RIP3 in colorectal cancer to overcome chemotherapeutic resistance

Abstract

Abstract Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the United States. When metastatic, chemotherapeutic drug 5-fluorouracil (5-FU) is typically used for treatment, but resistance often occurs. Many studies have shown that 5-FU induces apoptosis in cancer cells, but when apoptosis is inhibited, cell death can still occur, suggesting that other forms of cell death are occurring. Necroptosis, or regulated necrosis, is an alternative form of cell death, controlled by RIP1, RIP3, and MLKL, and its role in anticancer therapy remains unclear. TCGA RNAseq data show that RIP3 is significantly downregulated in primary CRC tumors, with RIP3 downregulation correlating with worse clinical outcomes. Analysis of numerous established CRC cell lines revealed that RIP3 expression was downregulated in ~50% of the cell lines, with low RIP3 expression being associated with decreased 5-FU sensitivity. These data led us to hypothesize that RIP3 expression and necroptosis may play a critical role in response to anticancer therapies, such as 5-FU, and that restoring defective necroptosis may enhance therapeutic sensitivity. Our preliminary studies have shown that RIP3-expressing (RIP3+) CRC cell lines are able to undergo both apoptosis and necroptosis in response to 5-FU, which could explain the enhanced sensitivity. As expected, knock-out of RIP3 in RIP3+ cells resulted in decreased 5-FU sensitivity, as well as abrogated necroptosis induction. Additionally, transient restoration of RIP3 in RIP3-silenced (RIP3-) CRC cells appeared to enhance 5-FU sensitivity, and so, we generated a stable RIP3-expressing cell line through retroviral infection. Although the stable RIP3-expressing cell line did not appear to be more sensitive to 5-FU alone, it did show enhanced sensitivity under conditions where apoptosis is inhibited. Together, our results suggest that RIP3 plays an important role in 5-FU-induced cell death in CRC, and that restoring RIP3 when the apoptosis pathway is implicated could provide a way to enhance 5-FU sensitivity and overcome resistance. The results from this project provide novel insight into the role of RIP3 in mediating response to anticancer therapy in CRC, which could be used for development of improved therapies and personalized medicine based on RIP3 status in the clinic. Citation Format: Kaylee A. Ermine, Dongshi Chen, Peng Wang, Jian Yu, Lin Zhang. Targeting necroptosis and RIP3 in colorectal cancer to overcome chemotherapeutic resistance [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr A015.