Inhibition of intestinal tumorigenesis in APC(MIN) mice by tart cherry anthocyanins and sulindac

Anthocyanins, a member of the flavonoid family of phytochemicals, previously have been found to inhibit the activities of cyclooxygenase (COX) enzymes. We hypothesized that tart cherry anthocyanins suppress intestinal tumorigenesis in ApcMin mice because compounds that inhibit COX potentially are protective against colon cancer development. A series of experiments were conducted to assess the influence of anthocyanins and a nonsteroidal anti-inflammatory drug, sulindac, on intestinal tumor development in ApcMin mice. First, we examined time frame of intestinal adenoma development in Apc Min mice. The numbers and size of adenomas in small intestine increased with age, whereas tumor number in the cecum and colon did not increase significantly with age. The volume of colonic tumors increased significantly after 75 days of age. These results characterized the early and rapid development and progression of intestinal tumors in ApcMin mice. We then conducted experiments to test the potential of anthocyanins to inhibit intestinal tumor development in ApcMin mice and growth of human colon cancer cell lines. Mice consuming anthocyanins and cyanidin in drinking water and a 20% tart cherry diet had fewer and smaller tumors in the cecum, whereas mice consuming sulindac in drinking water had more cecal adenomas. The mean diameter of adenomas in the small intestine was smaller in mice consuming sulindac, and larger in mice consuming the tart cherry diet, compared to mice consuming the control diet. Anthocyanins and cyanidin also reduced the growth of human colon cancer cell lines HT 29 and HCT 116. Based on these results, a second feeding study was conducted to determine effects of dietary anthocyanins and sulindac on (1) intestinal tumorigenesis in ApcMin mice, (2) expression and cellular localization of β-catenin, and (3) expression of target genes of the Wnt/β-catenin signaling pathway and global gene expression profiles. APCMin mice consuming dietary anthocyanins had significantly fewer adenomas in all three intestinal sections compared to mice consuming the control diet. Small intestinal adenomas in mice consuming sulindac were fewer in number and smaller in diameter compared to mice consuming anthocyanins, but mice consuming sulindac had more cecal adenomas compared to mice consuming anthocyanins. Sulindac did not influence the expression of β-catenin protein in intestinal epithelium, whereas anthocyanins increased β-catenin expression in the small intestine and cecum. Expression of mRNA of Apc, β-catenin and most of the target genes of Wnt/β-catenin signaling was not altered by treatment. cDNA microarray analysis identified several genes that were differentially expressed in response to treatment with anthocyanins or sulindac. Based on cellular expression of β-catenin and cDNA microarray analysis, we concluded that tumor inhibition in ApcMin mice by anthocyanins is unlikely to involve COX inhibition or inhibition of the Wnt/(3-catenin signaling pathway. Taken together, these results suggest that tart cherry anthocyanins and their aglycone, cyanidin, may reduce the risk of colon cancer by mechanisms that are unidentified at this time.