Abstract IA24: YAP in cancer and inflammation

Many common instigators drive the processes of inflammation and carcinogenesis. We have found such a common node in Yap1. In the context of cancer, YAP-TEAD complex is important in modulating the immune microenvironment, such that Yap 1-mediated transcriptional upregulation of CXCL5 by the prostate cancer cells in a PTEN/SMAD4 deficient mouse model leads to the recruitment of MDSCs through the interaction with CXCR2 on them. Depletion of MDSCs or pharmacologic inhibition of CXCR2 leads to impediment of cancer progression. In another well-established pancreatic cancer model (PDAC), Yap1/Tead2 governs escape from mutant Kras (G12D) inhibition through cooperative upregulation of E2F transcription factors to activate a cell cycle and DNA replication program. In the context of inflammation, specifically inflammatory bowel disease, telomere dysfunction is shown to activate pAtm/c-Abl-mediated phosphorylation and stabilization of Yap1 upregulating pro-IL-18, a major proinflammatory factor in IBD. This signaling axis cooperates with the gut microbiome stimulating cytosolic receptors causing activation of caspase-1 cleaving pro-IL-18 into mature IL-18. Epithelial IL-18 leads to recruitment of IFNγ-secreting T cells and other immunocytes provoking classical IBD pathology. Consistent with a role for DNA damage signaling driving IBD, newly diagnosed IBD patient samples exhibited elevated expression of pγH2AX, YAP1, Caspase-1, and IL-18 and significantly reduced telomere lengths. Telomerase reactivation in intestinal epithelium or pharmacologic inhibition of Atm, Yap1, or caspase-1 as well as antibiotic treatment of mice dramatically reduced IL-18 and inflammation. Thus, telomere dysfunction-induced activation of the Atm-Yap1-pro-IL-18 pathway identifies DNA damage signaling as a key instigator and promoter of IBD, illuminating novel therapeutic strategies. Citation Format: Guocan Wang, Xin Lu, Deepavali Chakravarti, Avnish Kapoor, Wantong Yao, Haoqiang Ying, Prasenjit Dey, Chiachin Wu, Denise Spring, Pingping Hou, Pingna Deng, Di Zhao, Baoli Hu, Mao Xizeng, Christopher Logothesis, Michael McArthur, Lynda Chin, Alan Wang, Sujun Hua, Hongai Xia, Gerald C Chu, Carol Lim, Eduardo Vilar, Sarah Blutt, Ronald A. DePinho. YAP in cancer and inflammation [abstract]. In: Proceedings of the AACR Special Conference on the Hippo Pathway: Signaling, Cancer, and Beyond; 2019 May 8-11; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(8_Suppl):Abstract nr IA24.