Functional experiments showed that TET1 inhibits cancer cells’ growth by repressing the WNT signaling pathway via demethylation of the promoters of the WNT inhibitors, Dickkopf Homolog 3 (DKK3) and Dickkopf Homolog 4 (DKK4), as reflected by the increase in 5-hmC and decrease in 5-mC levels in promoters of the respective genes in DOX-treated Caco-2 and SW48 cells as compared to controls. Here, DKK3 is linked to cancer.