β-catenin obstructs γδ T cell immunosurveillance in colon cancer through loss of BTNL expression

WNT/{beta}-catenin signaling endows cancer cells with proliferative capacity and immune-evasive functions that impair anti-cancer immunosurveillance by conventional, cytoxtoic T cells. However, the impact of dysregulated WNT signalling on unconventional, tissue-resident T cells, specifically in colon cancer is unknown. Here, we show that cancer cells in Apc-mutant mouse models escape immunosurveillance from gut-resident intraepithelial lymphocytes (IELs) expressing {gamma}{delta} T cell receptors ({gamma}{delta}TCRs). Analysis of late-stage tumors from mice and humans revealed that {gamma}{delta}IELs are largely absent from the tumor microenvironment, and that butyrophilin-like (BTNL) molecules, which can critically regulate {gamma}{delta}IEL through direct {gamma}{delta}TCR-interactions, are also downregulated. We could attribute this to {beta}-catenin stabilization, which rapidly decreased expression of the transcription factors, HNF4A and HNF4G, that we found to bind promoter regions of Btnl genes, thereby driving their expression in normal gut epithelial cells. Indeed, inhibition of {beta}-catenin signaling restored Btnl1 gene expression and {gamma}{delta} T cell infiltration into tumors. These observations highlight an immune-evasion mechanism specific to WNT-driven colon cancer cells that disrupts {gamma}{delta}IEL immunosurveillance and furthers cancer progression.