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. Author manuscript; available in PMC: 2011 Dec 15.
Published in final edited form as: Biochem Pharmacol. 2010 Jun 26;80(12):1771–1792. doi: 10.1016/j.bcp.2010.06.036

Figure 3. Effects of dietary polyphenols on the DNA methylation and histone modifications.

Figure 3

Simplified scheme demonstrates a number of epigenetic changes that occur during carcinogenesis. In cancers, tumor suppressor genes become “inactivated” (shown as red circles) while oncogenes are “activated” (green circles). Epigenetic gene expression regulation is a complex process and several key enzymes play crucial roles. DNA methyltransferase (DNMT) is responsible for transfer of methyl group to 5′-cytosine. Histone acetylases (HAT) and histone deacetylases (HDAC) are responsible for the acetylation and de-acetylation of lysine residues within histone tails, respectively. Because of these histone modifications, conformational changes in chromatin structure lead to changes in DNA accessibility for transcription regulators and polymerases. Polyphenols can impact these enzymes in specific ways induces reversibility of epigenetic dysregulation in cancer cells.