"Epigenetics in human cancer : 2 shorts stories about mechanisms"

Epigenetics encompasses changes in gene expression profiles that occur without alterations to the genomic DNA sequence of a cell. This arises from the modifications of the chromatin, a structure made from the wrapping of DNA around histone proteins. Modifications of chromatin occur both at the DNA and histone levels leading to crucial changes in the regulation of gene expression. Therefore epigenetics play a key role in many biological processes such as cell development, differenciation and function as well as in cancer. Our results highlight a previously unrecognized direct connection between two key epigenetic repression systems : Polycomb Group (PcG) proteins and DNA methylation. Further, we recently identify EMSY as a novel regulator of gene expression and provide new insight into the function of EMSY in sporadic breast cancer.