Pristimerin suppresses colorectal cancer through inhibiting inflammatory responses and Wnt/β-catenin signaling

Pristimerin, a triterpenoid, has exhibited potential anti-inflammatory and anti-tumor activities. Nevertheless, the role and mechanism of pristimerin in intestinal inflammation and colon cancer require further investigation. Here, we found that pristimerin protected mice from dextran sulfate sodium (DSS)-induced colitis, restoring epithelial damage and reducing tissue inflammation and inflammatory cell infiltration. In addition, pristimerin dramatically reduced the number and size of the tumors in a azoxymethane (AOM)/DSS-induced colitis-associated colorectal cancer (CAC) model. Furthermore, we found that pristimerin suppressed Wnt/beta-catenin signaling by RNA-Seq. Pristimerin inhibited Wnt/beta-catenin signaling via activation of GSK3 beta, thereby suppressing Wnt target gene expression in colon cancer HCT116 and HT-29 cells. In HCT116 colon cancer xenografts and APC(min/+) mice, which undergo spontaneous intestinal tumorigenesis, administration of pristimerin reduced the tumor progression and decreased the expression of phosphorylated GSK3 beta Ser 9, beta-catenin, cyclin D1 and c-Myc. These results suggest that pristimerin is a potent agent for preventing colon inflammation and carcinogenesis.