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Purpose:The cytokine IL22 promotes tumor progression in murine models of colorectal cancer. However, the clinical significance of IL22 in human colorectal cancer remains unclear. We sought to determine whether the IL22 pathway is associated with prognosis in human colorectal cancer, and to identify mechanisms by which IL22 can influence disease progression.Experimental Design:Transcriptomic data from stage II/III colon cancers in independent discovery (GSE39582 population-based cohort, N = 566) and verification (PETACC3 clinical trial, N = 752) datasets were used to investigate the association between IL22 receptor expression (encoded by the genes IL22RA1 and IL10RB), tumor mutation status, and clinical outcome using Cox proportional hazard models. Functional interactions between IL22 and mutant KRAS were elucidated using human colorectal cancer cell lines and primary tumor organoids.Results:Transcriptomic analysis revealed a poor-prognosis subset of tumors characterized by high expression of IL22RA1, the alpha subunit of the heterodimeric IL22 receptor, and KRAS mutation [relapse-free survival (RFS): HR = 2.93, P = 0.0006; overall survival (OS): HR = 2.45, P = 0.0023]. KRAS mutations showed a similar interaction with IL10RB and conferred the worst prognosis in tumors with high expression of both IL22RA1 and IL10RB (RFS: HR = 3.81, P = 0.0036; OS: HR = 3.90, P = 0.0050). Analysis of human colorectal cancer cell lines and primary tumor organoids, including an isogenic cell line pair that differed only in KRAS mutation status, showed that IL22 and mutant KRAS cooperatively enhance cancer cell proliferation, in part through augmentation of the Myc pathway.Conclusions:Interactions between KRAS and IL22 signaling may underlie a previously unrecognized subset of clinically aggressive colorectal cancer that could benefit from therapeutic modulation of the IL22 pathway.

The gastrointestinal (GI) tract is home to a large number and vast array of bacteria that play an important role in nutrition, immune system development, and host defense. In inflammatory bowel disease (IBD) there is a breakdown in this mutualistic relationship, resulting in aberrant inflammatory responses that can progress to colon cancer. Our studies in model systems have implicated innate lymphoid cells and production of IL-22 as key drivers of neoplasia and cancer in the intestine. In this presentation I will discuss new checkpoints that control bacteria-driven innate inflammation in the intestine as well as the functional effects of IL-22 on intestinal epithelial cells and interactions between IL-22 signaling and oncogenic mutations. Further understanding of the interactions between host genetics, gut microbiota, and deranged inflammatory pathways will yield new approaches to patient stratification and personalized therapy. Citation Format: Fiona Powrie, Sarah McCuaig, Nathan West, Grigory Ryzhakov. Inflammation-driven cancer: Host and microbial pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr SY19-03. doi:10.1158/1538-7445.AM2017-SY19-03