Epigenetic refers to the study of heritable changes of DNA In gene expression. It has the ability to influence what genes are turned on or off in our body. The aim of epigenetic research is to understand heritable gene regulation that is not encoded in the DNA sequence. The paper talks about the computational methods that used to solve epigenetic problems and how describe the concepts of cancer epigenetics. Epigenetics talks about how gene functions can be changed by not changing the DNA sequences at all. The field of epigenetics is among the fastest moving area in the molecular biology, it opens up an unprecedented research projects and analysis of epigenetic mechanisms. They also open up ideas for early diagnosis and treatments for cancers. Epigenetic regulation of the genes influences the gene expression by different mechanisms. They can either activate the genes or repress the chromatins inside the nucleus. One of the most important epigenetic mechanisms is called DNA methylation. DNA methylation usually happens in the regions where the CpG Islands are more abundant in the gene/s promoter region. What happens during DNA methylation is that a methyl group adds to the DNA strand by replacing the hydrogen atoms from the cytosine bases.. The process does not transcribe the cytosine into mRNA; it makes the chromatin more compactable, so that the transcriptions factors might not be able to bind to the promoters.
There are two types of DNA methylations: hypomethylation and hypermethylation, both of the methylations have been associated with cancer. Hypomethylation refers to less DNA methylation than the standard in the DNA and leads to up-regulation of the genes. It can cause cancer if the genes associates with tumorigenesis are upregulated. For example, histone H3k9 is used for transcriptional activation, it is associated with breast cancer and esophageal cancer. If hypomethylation happen in H3K9, they would be overexpressed and increase the chance of having breast and esophageal cancer. Repetitive elements make up at least half of the genome and they are highly methylated. Repetitive elements pack the DNA into heterochromatin (condensed chromatin structure) and ensure the stability of the chromosome. Hypomethylation of these regions can cause chromatin decondensation and affect the stability of the chromosome. Alu refers to short interspersed elements (SINEs) and LINE refers to long interspersed elements. They are the most studied repetitive elements in cancers. They contain promoter sequences to initiate gene transcription if unregulated. LINE-1 and Alu elements are normally silenced through DNA methylation. Hypomethylation of these two elements might cause cancer, because the activation of the LINE-1 and Alu and the rearrangement of DNA sequences by deletions or inversions. Hypermethylation means more DNA methylation in the DNA sequence, they can cause cancer as well as hypomethylation. Hypermethyations always happen in CpG islands. CpG stands for Cytosine-phosphate-guanosine. It is the regions that contain cytosine and guanosine in a high frequency than