Quercetin Is Able to Demethylate the p16INK4a Gene Promoter

<i>Background:</i> Quercetin is a flavonoid found ubiquitously in nature. Studies in vitroand in vivohave suggested that quercetin may have a protective role against colon cancer. <i>Methods:</i> 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. <i>Results:</i> 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. <i>Conclusion:</i> All these data suggest that quercetin has antitumor properties, probably via demethylation of the p16INK4a gene promoter.