Figure 1.

Disruption of CTCF binding at the miR-125b1 CpG island in human cancers. In normal breast cells, CTCF might prevent the recruitment of epigenetic silencing components, such as DNA methylation and repressive histone modifications, and also favors an open chromatin structure. Meanwhile, in breast cancer cells, the loss of CTCF is associated with CpG island methylation and the gain of repressive histone modifications such as histone H3 K9 trimethylation and histone H3 K27 trimethylation. Open circle, unmethylated DNA; filled circle, methylated DNA; H3K9Me, histone H3 K9 methylation; H3K27Me, histone H3 K27 methylation.