Multiple studies in recent years link consumption of green tea to decreased risk of human disease, including many forms of cancer. Now, scientists in Japan reveal evidence that the 67-kDa laminin receptor (67-LR) mediates this effect.
The investigators explain that the laminin receptor is expressed on several types of tumor cells, and its expression level “strongly correlates with the risk of tumor invasion and metastasis.”Previous research has identified green tea’s major polyphenol, (-)-epigallocatechin-3-gallate (EGCG), as it active antitumorigenic component (see Reuters Health report, October 17 2003). Dr. Hirofumi Tachibana and colleagues at Kyushu University in Fukuoka found that all-trans-retinoic acid enhances EGCG binding to the 67-LR on the surface of cancer cells. According to their report in Nature Structural and Molecular Biology, published online March 14, EGCG at a plasma concentration equivalent to that achieved after drinking two or three cups of green tea inhibited growth of lung cancer cells transfected with the 67-LR gene. Adding laminin or an antibody to 67-LR to the mix reduced EGCG’s binding affinity. “Increasing the expression of (67-LR) may confer a much higher EGCG potency, similar to the effect of a tumor suppressor gene,” Dr. Tachibana’s group concludes. “Characterizing the mechanisms by which EGG acts through this 67-LR should help in the design of new strategies to prevent cancer.” (Source: Nat Struct Mol Biol 2004: Reuters Health: March 2004: Oncolink)