The nitty gritty of how green tea fights skin cancer
In skin cancer cells, the cancer fighting genes (tumor suppressor genes) are silenced (do not work – are out of the cancer fighting business). The cancer fighting genes do not work because they are shut down because a specific region of the gene becomes over methylated by toxins such as the chemicals in tobacco smoke or the pollutants in diesel fumes (carbon-hydrogen groups are added to the specific regions on the genes shutting them down; they can no longer protect us from cancer).
On the other hand normal-good, cancer preventing methylation by the B-complex vitamin folic acid that occurs evenly throughout the gene is not present in tumors. Shutting down or reviving genes is called epigenetics. When you drink green tea to fight cancer you are practicing epigenetics and when a pregnant woman takes folic acid she is practicing epigenetics making her baby smarter (folic acid during the first trimester of pregnancy improves intelligence and prevents birth defects).
Some phytochemicals from very healthy foods decrease the risk of cancer by modifying epigenetic processes. In this study researchers from the Department of Dermatology, University of Alabama at Birmingham added EGCG, the major ingredient in Green Tea, to skin cancer cells to see if it could revive tumor suppressor genes silenced via methylation (reversing bad epigenetics in other words). The researchers choose human skin cancer (carcinoma) cells called a431 cells as their model for research; carcinoma is a dangerous form of skin cancer. Good news, the higher the concentration of EGCG the better it was at reversing the suppression of tumor suppressing genes.
EGCG cleaned up a number of important genes and inhibited the enzyme histone deacetylase; this enzyme removes acetyl groups from amino acids making them unstable and adding to the cancer process. Histone deacetylase inhibitors (HDAC) are currently the focus of intense research because they are so promising for fighting cancer. Several HDAC inhibitors have shown impressive antitumor activity in vivo with remarkably little toxicity in preclinical studies and are currently in phase I clinical trial. The EGCG besides being a HDAC also improved the acetylation of important amino acids such as lysine in specific spots that fight cancer and removed methylation from areas that support cancer.
All of this activity of EGCG resulted in the reactivation of previously silenced tumor suppressing genes including p16 (regulates the cell cycle and prevents mutations of skin cells and if it is silenced you have a greater likelihood of developing deadly melanoma skin cancer) and other cancer fighting genes. The study is published online ahead of print in the January 5th, 2011 edition of the journal Carcinogenesis.