Cancer is believed to be the result of, both, genetics and epigenetics. Epigenetics has given new understanding to the development of cancers of all types. Epigenetic changes alter gene expression but don’t alter the sequence of DNA. Even though they are inheritable, they are reversible. They can be modified by diet, environment and pharmaceuticals. For all these reasons, they are considered to be good targets for cancer therapy.
The 3 mechanisms of epigenetics are DNA methylation, histone modification and alteration of regulation by non-coding microRNAs. Unlike mutations, epigenetic changes can be reversed. Methylation silenced genes can be demethylated. Histones can be changed by acetylation and methylation by nutrients, drugs and diet changes.
Islands of hypomethylation in genes are often seen during development and in normal cells that haven’t differentiated into more mature cells. Hypermethylation of these areas can lead to silencing of genes. Many human cancers show increased natural DNA methylation, causing gene silencing as part of the cancer process. Important chemicals for methylation are folic acid, B vitamins and SAM (S-adenosyl methionine,) which can change gene expression. Diets deficient in folate, choline, and methionine, sources of methylation in animals, can trigger liver cancer.
Histone modification is important in gene modification in the development of cancer. The type of histone modification determines whether there is suppression or activation of genes. Histone modifications are reversible. Acetylation can be deacetylated. A large number of histone altering enzymes have been identified, including polyphenols.
MicroRNAs alter gene regulation. They work by facilitating gene splicing, etc. Aberrant expression of these RNAs has been associated with cancer progression. MicroRNAs are important and are used to classify human cancers.
Studies with mice have shown that “an individual’s adult health is strongly influenced by early prenatal factors, and that our health is not only determined by what we eat, but also what our parents ate.”
Drugs which alter genetic changes are being studied. The problem is that the chemicals intended to inhibit may sometimes act to promote gene expression and can cause cancer progression.
Diet and environmental stresses can alter epigenetics. Some of the dietary polyphenols which can cause beneficial environmental changes are in green tea, turmeric, soybeans and broccoli. They are helpful for chemoprevention. Polyphenols are a large part of the human diet and can play a large part in cancer prevention. There may be 8000 different polyphenols. Phenolic acids, flavonoids, stilbenes and lignans are most abundant. Polyphenols can trigger apoptosis (death from within cells) in cancer cells.
The following alter DNA methylation: Tomatoes (lycopene,) apples (phloretin) and citrus (hesperidin.) The following alter histone deacetylation: Cashew nuts (anacardic acid,) grapes (resveratrol) and garlic (allyl mercaptan.) The following alter histone deacetylation and DNA methylation: Turmeric (curcumin,) cinnamon (courmaric acid,) soybean (genistein,) tea (EGCG,) coffee (caffeic acid,) and broccoli (isothiocyanates.)
CONCLUSION: Further research will, most likely, lead to further understanding of the anticancer effects of polyphenols on cancer. Dietary polyphenols have the potential to have beneficial effects on cancer due their ability to alter epigenetic changes.
NOTE: A study by Frankenfeld, CL., et al, showed a lower risk of non-Hodgkin lymphoma among people with high intake of polyphenols (PMID: 18469269.) Rao, CV., et al., found that the flavonoid, quercetin, was beneficial in gastroesophageal reflux (PMID: 18547560.) Heiss, C., et al, found that diets rich in fruits and vegetables high in flavonoids were useful in cardiovascular disease prevention (PMID: 20852295.)
Waldecker, M., et al, wrote an article about butyrate as a histone deacetylase inhibitor (18262392.) Marks, PA., et al, wrote an article about histone deacetylase chemicals in the body which are targets for treatment of cancer, neurodegenerative diseases, etc. (PMID: 19459166.)
Read more about natural health products that prevent cancer. Read about cancer chemoprevention by Amla berry and by American ginseng. One of the best sources of cancer preventing polyphenols is green tea, especially in the form of Matcha green tea. Read about the influence of vegan, vegetarian and omnivore diets on folic acid and B-12 levels.