Complex cross-talk between EZH2 and miRNAs confers hallmark characteristics and shapes the tumor microenvironment

Cancer epigenetic mechanisms support the acquisition of hallmark characteristics during oncogenesis. EZH2 - an important histone methyltransferase that writes histone H3 lysine 27 trimethylation marks - is known to be dysregulated in cancer cells. However, the interactions between EZH2 and miRNAs that form a complex network of cross-talk and reciprocal regulation that enable cancer cells to acquire hallmark characteristics have been relatively poorly appreciated. The specific functions of EZH2 appear to be regulated by a vast array of miRNAs, which direct EZH2 toward regulation over the development of specific hallmark characteristics. This review discusses recent advances in the understanding of EZH2, focusing on its collaboration with miRNAs to orchestrate oncogenesis. These epigenetic processes promote the evasion of apoptosis/cell cycle arrest, cellular dedifferentiation and the establishment of a tumor microenvironment that facilitates local cancer cell invasion, anti-cancer drug resistance and evasion of the immune response.