Interleukin-11-expressing fibroblasts have a unique gene signature correlated with poor prognosis of colorectal cancer

Interleukin (IL)-11 is a member of the IL-6 family of cytokines and involved in multiple cellular responses, including tumor development. However, the origin and functions of IL-11-producing (IL-11+) cells are not fully understood. To characterize IL-11+ cells in vivo, we generated Il11 reporter mice. IL-11+ cells appeared in the colon of murine tumor and acute colitis models. Il11ra1 or Il11 deletion attenuated the development of colitis-associated colorectal cancer. IL-11+ cells expressed fibroblast markers, and genes associated with cell proliferation and tissue repair. IL-11 induced the activation of colonic fibroblasts and epithelial cells through phosphorylation of STAT3. Human cancer database analysis revealed that a set of genes enriched in IL-11+ fibroblasts was elevated in human colorectal cancer, and correlated with reduced recurrence-free survival. Together, IL-11+ fibroblasts activate both tumor cells and fibroblasts via secretion of IL-11, thereby constituting a feed forward loop between tumor cells and fibroblasts in the tumor microenvironment. To characterize IL-11+ fibroblasts that appeared in colitis, we used a cell sorter to isolate EGFP+ and EGFP- fibroblasts from the colon of DSS-treated Il11-Egfp reporter mice and compared their gene expression profiles by RNA-seq analysis.