Epigenomic Analysis in Toxicology

Abstract

Epigenetic modifications are essential for development, differentiation, and reprogramming. They are inherited upon somatic cell replication, and include DNA methylation and histone modifications. Abnormality of epigenetic modifications is deeply involved in human cancers, as known by global hypomethylation and regional hypermethylation. Recent findings on the high fraction of cells affected in normal‐appearing tissues indicated that epigenomic alterations are also involved in acquired disorders other than cancers. In spite of the deep involvement of epigenomic alterations in human diseases, only limited information is available for inducers of epigenetic changes, including aging, chronic inflammation, virus infection, disturbances in one carbon metabolism, and some chemicals. One of the reasons why a very limited number of chemicals are known as inducers of epigenetic alterations (epimutagens) is the lack of a sufficiently convenient and sensitive assay system. Toxicological considerations from the viewpoint of epigenomics are critically important, and epigenomic toxicology has just started.