Modified apple polysaccharide prevents against tumorigenesis in a mouse model of colitis-associated colon cancer: role of galectin-3 and apoptosis in cancer prevention.

Background: Colorectal cancer (CRC) is one of the most common and preventable cancers. Regular consumption of apples is conducive to reduction in CRC risk. Aim of the study: To evaluate effects of modified apple polysaccharide (MAP) on tumorigenesis in a mouse model of colitis-associated colon cancer. Methods: One hundred male ICR mice were administered with 1, 2-dimethyl-hydrazine (DMH) and dextran sodium sulfate (DSS). Forty mice were given no further treatment, the rest were fed basal diet blended with three different doses of MAP; 2.5, 5, and 10% (20 mice in each group). Results: MAP significantly protected ICR mice against DMH/DSS-induced tumorigenesis. The incidence of tumor development was 90% (18/20) in the mice treated with DMH/DSS, but that was reduced to 25% (5/20), 15% (3/20), and 5% (1/20), respectively, in the mice treated with basal diets plus 2.5, 5, and 10% of MAP. Study of apoptosis of colonic epithelial cells revealed that MAP moderately increased apoptosis, suggesting that the anti-tumor potency of MAP was probably attributed to its ability to induce apoptosis. Western blot analysis demonstrated that carbohydrate-binding protein galectin-3 changed in both the nucleus and the cytoplasm during the process from colitis to colon cancer in the model. And MAP could inhibit the binding of galectin-3 to its ligand: this is, at least in part, the possible mechanism of MAP by enhancing apoptosis and preventing tumorigenesis. Conclusions: These data suggest that MAP has a potential role in clinical prevention and treatment for colon cancer. [ABSTRACT FROM AUTHOR]