IL22 signaling plays an important role in maintaining gastrointestinal epithelial barrier function, cell proliferation and protection of intestinal stem cells from genotoxicants. Emerging studies indicate that the aryl hydrocarbon receptor (AhR), a ligand activated transcription factor, promotes production of IL22 in gut immune cells. However, it remains to be determined if AhR signaling can also affect the responsiveness of colonic epithelial cells to IL22. Here, we show that IL22 treatment induces the phosphorylation of STAT3, inhibits colonic organoid growth, and promotes colonic cell proliferation in vivo. Notably, intestinal cell specific AhR knockout (KO) reduces responsiveness to IL22 and compromises DNA damage response following exposure to carcinogen, in part due to the enhancement of SOCS3 expression. Deletion of SOCS3 increases levels of pSTAT3 in AhR KO organoids, and phenocopies the effects of IL22 treatment on wildtype (WT) organoid growth. In addition, pSTAT3 levels are inversely associated with increased AOM/DSS induced colon tumorigenesis in AhR KO mice. These findings indicate that AhR function is required for optimal IL22 signaling in colonic epithelial cells and provide rationale for targeting AhR as a means of reducing colon cancer risk.
Loss of Aryl Hydrocarbon Receptor Promotes Colon Tumorigenesis in ApcS580/+; KrasG12D/+ Mice