Quercetin Is Able to Demethylate the p16INK4a Gene Promoter

BACKGROUND: Quercetin is a flavonoid found ubiquitously in nature. Studies in vitro and in vivo have suggested that quercetin may have a protective role against colon cancer. METHODS: We selected the human colon cancer cell line RKO to investigate the effects of quercetin in vitro. RKO cells were treated with different concentrations of quercetin. RESULTS: In comparison to the control, quercetin was able to inhibit the growth of RKO cells, as measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Untreated RKO cells demonstrated almost complete methylation of the p16INK4a gene. Hypermethylation of the p16INK4a gene was successfully reversed after 120 h of treatment with quercetin. Expression of the p16INK4a gene was restored in a concentration-dependent manner. CONCLUSION: All these data suggest that quercetin has antitumor properties, probably via demethylation of the p16INK4a gene promoter.