**7. Conclusion**

Many studies after the first discovery of epigenetic changes have shown that epigenetic modifications are quite important in natural flow of life and that many genes are mechanisms used for expression and inactivation when needed.

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Furthermore, as these mechanisms are understood better, they have been associated with many pathological conditions, from cancer to mental retardations such as fragile X and Prader-Willi Angelman, to chromosomal instability. In this regard, such diseases have emerged in new therapeutic targets. Chemical agents such as 5-azacytidine and 5-aza-2′-deoxycytidine, which inhibit methylation by binding to and inhibiting DNMT enzyme, are now being tested in phase II-III studies [35–38]. Furthermore, use of oligonucleotides that bind to promoter regions at specific gene level and perform gene inhibition is seen as approaches that may contribute to cancer treatments [39–41].

In addition, histone acetyltransferase inhibitors, which inhibit formation of epigenetic modifications at histone level, have emerged as novel cancer treatment agents. For example, H3-H4 of a soy protein Lunasin has been found to exhibit anticancer properties in mammals by suppressing histone acetylation. Wenyi et al. have shown that YEAST domain, an acetyl lysinebinding module, is effective in the development of cancer, and this domain appears to be the target for anticancer therapies. It seems that such approaches in the future will start to give more successful results [42].

In light of the information presented above, one may conclude that methylation is a highly important genomic mechanism for the cell from unicellular organisms to multicellular organisms. This mechanism is seen in bacteria, mitochondria and all eukaryotic cells in proportion to the complexity and development level of the organism. The identification of methylated regions is as important as the methylation process itself, as this may allow identifying several potential novel targets related to subject matters such as the development mechanism of diseases, certain roles in cancer development and bacterial resistance.
