Genetics and Epigenetics in Tumorigenesis: Acting Separately or Linked?

Review Article

Austin J Clin Med. 2014;1(4): 1016.

Genetics and Epigenetics in Tumorigenesis: Acting Separately or Linked?

Zhu X* and Wetta H

Department of Environmental Health, University of Cincinnati College of Medicine, USA

*Corresponding author: Xuegong Zhu, Department of Environmental Health, University of Cincinnati College of Medicine, Kettering Laboratory, 3223 Eden Avenue, Cincinnati, OH 45267-0056, USA

Received: May 31, 2014; Accepted: August 04, 2014; Published: August 11, 2014

Abstract

Tumorigenesis represents both genetic and epigenetic alterations. Genetic changes are defined as genomic DNA sequence changes, including point mutation, single nucleotide polymorphism (SNP) or copy number variability (CNV), including loss of heterozygozity (LOH), gain copy number or deletion. On the other hand, epigenetic modification is responsible for regulation of gene expression without changing the underlying DNA sequence. Such mechanisms include DNA methylation, post-translational modifications of the histone proteins, and micro RNA, resulting in selective gene activation and/or in activation. As opposed to solely isolated genetic and epigenetic components acting in tumorigenesis, the complex nature of cancer seems to stem from the interaction of these mechanisms.

Keywords: Genetics; Epigenetics; Tumor

Tumorigenesis

Genes associated with disease susceptibility can contribute to the onset of cancer and other diseases through multiple mechanisms. As shown in Figure 1, there are two copies, or alleles, of every gene, which are located on two separate chromosomes: one from the mother and one from the father. If a gene is an oncogene, an active mutation or epigenetic activation of only one gene copy is enough to drive expression of the gene. For example, MAGE-A3 is not expressed in normal pituitary tissue; however it is activated in pituitary tumors through promoter DNA de-methylation [1].