February 4, 2009

Green tea makes cancer drug ineffective

U.S. researchers found that the widely used supplement of green tea renders a cancer drug for myeloma and lymphoma completely ineffective.

Researchers at the University of Southern California found that a component of green tea extract called EGCG destroys any anticancer activity of the drug Velcade in tumor-bearing mice. The finding is published online ahead of print in the journal Blood.

Our finding that GTE or EGCG blocked the therapeutic action of Velcade was completely unexpected, lead author Axel H. Schonthal of the Keck School of Medicine of the University of Southern California said in a statement. Our hypothesis was that GTE or EGCG would enhance the anti-tumor effects of Velcade, and that a combination of GTE with Velcade -- or EGCG with Velcade -- would turn out to be a superior cancer treatment as compared to treatment with Velcade alone.

Herbal remedies, including green tea, have become a popular remedy for cancer patients dealing with side effects of chemotherapy. However, these supplements are unregulated and, for most, their beneficial and/or detrimental effects have not been qualified through research, Schonthal said.

Using preclinical models and tumor-bearing mice, the researchers found that the unusually effective blockage of Velcade's therapeutic activity was based on the chemical interaction between molecules. The EGCG molecule and the Velcade molecule were able to form chemical bonds, meaning that the Velcade molecule could no longer bind to its intended target inside the tumor cells, Schonthal explained.