Effects of Dietary Natural Compounds on DNA Methylation Related to Cancer Chemoprevention and Anticancer Epigenetic Therapy

Abstract

Aberrations in function and expression of a wide variety of genes are the hallmarks of cancer cells. A growing body of evidence shows that these aberrations are affected by genetics and epigenetics which cooperate at all stages of cancer development. Epigenetic alterations (especially DNA hypermethylation) resulting in the silencing of key tumor suppressor genes have attracted signifi cant attention. In contrast to genetic changes, epigenetic modifi cations are reversible and responsive to developmental, physiological, environmental, dietary, and pathological signals. A number of studies provide evidence that some natural bioactive compounds found in food and herbs can infl uence gene expression via modulation of the DNA methylation process. It has been demonstrated that some polyphenols (i.e., catechins, quercetin, myricetin, genistein, resveratrol) and vitamins (i.e., retinoic acid, vitamin D 3 ) exert a profound inhibitory effect on DNA methyltransferase enzyme activity and/or DNA methyltransferase gene expression and contribute to reactivation of methylation -silenced tumor suppressor genes in cancer cells leading to blocking of cancer development. This raises the possibility that the natural compounds can be a new approach to anticancer therapy. Moreover, their presence in widely available food products can bring about the high effi cacy of the compounds in cancer chemoprevention. This chapter gives a short overview of the mechanisms of DNA methylation inhibition by the selected bioactive food components and their potential use in cancer prevention and/or epigenetic therapy.