Abstract

Epigenetic modifications are heritable changes to gene expression without physical changes to the actual DNA sequence. The most widely studied epigenetic modification is DNA methylation, as it is influenced by aging, diet, diseases and the environment. DNA methylation involves direct chemical modification to the DNA and plays an important role in gene regulation by preventing proteins from binding to certain regions of the DNA, which causes these regions to be repressed. It is essential for normal development, cell differentiation and regulation of cellular biology. The DNA methylation landscape of each unique cell type helps to determine which genes are expressed and silenced. It is well known today that the accumulation of both genetic and epigenetic abnormalities contributes to the development of cancers. Aberrant DNA methylation is a hallmark of cancer. During cancer development and progression, the methylation landscape undergoes aberrant remodelling. Recently within cancer research, the advancements in DNA methylation mapping technologies have enabled methylation landscapes to be studied in greater detail, sparking new interest in how the methylation landscape undergoes a change in cancer and possible applications of DNA methylation. This chapter focuses on reviewing DNA methylation landscapes in normal cells and then how they are altered in cancer. It also discusses the applications of DNA methylation as cancer biomarkers.