Table 1.

Epigenetic interplay involving DNA and H3K27 methylation relevant to gene regulation and colorectal cancer

Epigenetic interaction	Molecular event	Biological relevance or consequence	Reference
PRC2-PRC1	H3K27me3 and H2AK119Ub co-dependently recruit respective complexes	Recurrent deregulation in CRC	55,56
	Loss of Bmi1, a component of PRC1, relieves repression of the target genes	Promotion of invasion and epithelial to mesenchymal transition	58,59
PRC2-ncRNA	HOTAIR guides PRC2 to target genes destined for suppression	Increased invasion and metastasis in CRC	64–67
PRC2-H3K4me3	H3K27me3 and H3K4me3 co-occupancy poise expression of developmental genes	Abnormal differentiation and proliferation	44
PRC2-DNA methylation	Mega base H3K27me3 enriched regions associated with broad DNA hypomethylation	Compromised higher order chromatin structure in CRC	54
	Hypomethylated developmental enhancers maintained by PRC2	Ectopic reactivation of enhancers in adult tissue upon PRC2 loss	115
DNA methylation-H3K9me3	Cooccurrence of H3K9me3 and DNA methylation at heterochromatin region	Reduction in nuclear peripheral heterochromatin accompanied by loss of DNA methylation in CRC	54