Epigenetics and DNA methylation in cancer

Figure 2 The methylation scenario of normal and cancer cells. A: In the mammalian genome the amount of CpGs is low and most these sites are methylated (black lollipops). CGIs are usually located in gene promoters and are generally unmethylated (white lollipops), irrespective of gene expression status. The bodies of active genes are enriched in hydroxymethylated CpGs (grey lollipops); B: In cancer cells both DNA methylation and hydroxymethylation are reduced even if some CpG island have been found to be aberrantly hypermethylated. Adapted by Sproul et al[4], 2013. 5hmC: 5 hydroxymethylcytosine.