Table 3 Epigenetic factors from [1]

Epigenetic factors. One of the widely studied epigenetic factors is methylation [24–26]. Its occurrence leads to decrease in the gene expression which affects the working of Wnt signaling pathways. Such characteristic trends of gene silencing like that of secreted frizzled-related proteins (SFRP) family in nearly all human colorectal tumor samples have been found at extracellular level [27]. Similarly, methylation of genes in the Dickkopf (DKKx [28, 29]), Dapper antagonist of catenin (DACTx [2]), and Wnt inhibitory factor-1 (W I F1 [30]) family are known to have a significant effect on the Wnt pathway. Also, histone modifications (a class of proteins that help in the formation of chromatin which packs the DNA in a special form [31]) can affect gene expression [32]. In the context of the Wnt signaling pathway, it has been found that DACT gene family shows a peculiar behavior in colorectal cancer [2]. D A C T1 and D A C T2 showed repression in tumor samples due to increased methylation while D A C T3 did not show obvious changes to the interventions. It is indicated that D A C T3 promoter is simultaneously modified by both the repressive and activating (bivalent) histone modifications ([2]).