Blockade of β-Catenin-Induced CCL28 Suppresses Gastric Cancer Progression via Inhibition of Treg Cell Infiltration

Dysregulation of Wnt/beta-catenin signaling is frequently observed in human gastric cancer. Elucidation of the tumor immune microenvironment is essential for understanding tumorigenesis and for the development of immunotherapeutic strategies. However, it remains unclear how beta-catenin signaling regulates the tumor immune microenvironment in the stomach. Here, we identify CCL28 as a direct transcriptional target gene of beta-catenin/T-cell factor (TCF). Protein levels of beta-catenin and CCL28 positively correlated in human gastric adenocarcinoma. beta-Catenin-activated CCL28 recruited regulatory T (Treg) cells in a transwell migration assay. In a clinically relevantmouse gastric cancer model established by Helicobacter (H.) felis infection and N-methyl-N-nitrosourea (MNU) treatment, inhibition of beta-catenin/TCF activity by a pharmacologic inhibitor iCRT14 suppressed CCL28 expression and Treg cell infiltration in the stomach. Moreover, an anti-CCL28 antibody attenuated Treg cell infiltration and tumor progression in H. felis/MNU mouse models. Diphtheria toxin-induced Treg cell ablation restrained gastric cancer progression in H. felis/MNU-treated DEREG (Foxp3-DTR) mice, clarifying the tumor-promoting role of Treg cells. Thus, the beta-catenin-CCL28-Treg cell axis may serve as an important mechanismfor immunosuppression of the stomach tumor microenvironment. Our findings reveal an immunoregulatory role of beta-catenin signaling in stomach tumors and highlight the therapeutic potential of CCL28 blockade for the treatment of gastric cancer. Significance: These findings demonstrate an immunosuppressive role of tumor-intrinsic beta-catenin signaling and the therapeutic potential of CCL28 blockade in gastric cancer.