Tumour-associated changes in intestinal epithelial cells cause local accumulation of KLRG1+ GATA3+ regulatory T cells in mice.

CD4+ Foxp3+ regulatory T (Treg) cells include differentiated populations of effector Treg cells characterized by the expression of specific transcription factors. Tumours, including intestinal malignancies, often present with local accumulation of Treg cells that can prevent tumour clearance, but how tumour progression leads to Treg cell accumulation is incompletely understood. Here using genetically modified mouse models we show that ablation of E-cadherin, a process associated with epithelial to mesenchymal transition and tumour progression, promotes the accumulation of intestinal Treg cells by the specific accumulation of the KLRG1+ GATA3+ Treg subset. Epithelial E-cadherin ablation activates the ß-catenin pathway, and we find that increasing ß-catenin signals in intestinal epithelial cells also boosts Treg cell frequencies through local accumulation of KLRG1+ GATA3+ Treg cells. Both E-cadherin ablation and increased ß-catenin signals resulted in epithelial cells with higher levels of interleukin-33, a cytokine that preferentially expands KLRG1+ GATA3+ Treg cells. Tumours often present reduced E-cadherin expression and increased ß-catenin signalling and interleukin-33 production. Accordingly, Treg cell accumulation in intestinal tumours from APCmin/+ mice was exclusively due to the increase in KLRG1+ GATA3+ Treg cells. Our data identify a novel axis through which epithelial cells control local Treg cell subsets, which may be activated during intestinal tumorigenesis.

DNA methylation of E-cadherin is a priming mechanism for prostate development.

In prostate and other epithelial cancers, E-cadherin (CDH1) is downregulated inappropriately by DNA methylation to promote an invasive phenotype. Though cancer frequently involves a reawakening of developmental signaling pathways, whether DNA methylation of Cdh1 occurs during organogenesis has not been determined. Here we show that DNA methylation of Cdh1 mediates outgrowth of developing prostate ducts. During the three-day gestational window leading up to and including prostate ductal initiation, Cdh1 promoter methylation increases and its mRNA and protein abundance decreases in epithelium giving rise to prostatic buds. DNA methylation is required for prostate specification, ductal outgrowth, and branching morphogenesis. All three endpoints are impaired by a DNA methylation inhibitor, which also decreases Cdh1 promoter methylation and increases Cdh1 mRNA and protein abundance. A CDH1 function-blocking antibody restores prostatic identity, bud outgrowth, and potentiates epithelial differentiation in the presence of the DNA methylation inhibitor. This is the first study to mechanistically link acquired changes in DNA methylation to the normal process of prostate organogenesis. We propose a novel mechanism whereby Cdh1 promoter methylation restricts Cdh1 abundance in developing prostate epithelium to create a permissive environment for prostatic bud outgrowth. Thus, DNA methylation primes the prostate primordium to respond to developmental cues mediating outgrowth, differentiation and maturation of the ductal network.