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Epigenetics And Cancer Essay

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Epigenetics and Cancer
Introduction:
Cancer is beyond mutations. By definition, epigenetics is the change in gene translation that is caused by alterations not directly due to genetic mutations in the DNA sequence. The 2 main mechanisms are DNA methylation and covalent modification of histones. By methylation, certain molecular tags (methyl groups) bind to a specific sequence of a gene, that results in its disability hence incapable of being translated into its appropriate protein product. These changes affect the cell’s functions leaving its DNA unchanged. Epi is derived from Latin meaning above; hence an epigenetic configuration overlies our genetic predispositions.

DNA methylation and Cancer:
DNA methylation primarily occurs within sites in the DNA sequence known as CpG dinucleotides, which is a 2 base pair sequence involving a Cytosine bonded to a Guanine by a phosphodiester bond.
DNA methylation is catalyzed by the enzyme: DNA methyl trasnferase (DNMTs). Methylation of DNA segments leads to the silencing of transposable elements. Hence this mechanism is repressive to transcription, by that enhancing genomic stability. However, there exist “CpG” islands that are associated with gene promoters that escape methylation hence stability.
Hypermethylation of CpG islands at tumor suppressor genes turns them off, while hypomethylation leads to the instability and inappropriate activation of oncogenes and transposable elements. Methylation can be directly related to genetic mutations, an example of this case is methylated cytosine. Methylated cytosine mutates spontaneously in vivo through deamination to give thymine. According to Andy Bannister (n.d.), “37% of somatic p53 mutations and 58% of germ line mutations occur at methylated...

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