DNA Methylation Changes in Cancer
Samson Mani and Zdenko Herceg
from: Epigenetics: A Reference Manual (Edited by: Jeffrey M. Craig and Nicholas C. Wong). Caister Academic Press, U.K. (2011)
DNA methylation is an important regulator of gene transcription and a large body of evidence has demonstrated that aberrant DNA methylation is associated with unscheduled gene silencing, and the genes with high levels of 5-methylcytosine in their promoter region are transcriptionally silent. DNA methylation is essential during embryonic development, and in somatic cells, patterns of DNA methylation are generally transmitted to daughter cells with a high fidelity. Aberrant DNA methylation patterns have been associated with a large number of human malignancies and found in two distinct forms: hypermethylation and hypomethylation compared to normal tissue. Hypermethylation is one of the major epigenetic modifications that repress transcription via promoter region of tumour suppressor genes. Hypermethylation typically occurs at CpG islands in the promoter region and is associated with gene inactivation. Global hypomethylation has also been implicated in the development and progression of cancer through different mechanisms. This chapter will focus on DNA methylation as the major epigenetic mechanism involved in normal biological processes and abnormal events leading to cancer development. It will also focus on the interaction between DNA methylation and other epigenetic mechanisms read more ...