Green tea catechins and vitamin E inhibit angiogenesis of human microvascular endothelial cells through suppression of IL-8 production.
Epidemiological and animal studies have indicated that consumption of green tea and high vitamin E intake are associated with a reduced risk of developing certain forms of cancer. However, the inhibitory mechanism of green tea catechins and vitamin E in angiogenesis, an important process in tumor growth, has not been well established. In the present study, alpha-tocopherol and several major catechins of green tea (catechin, epicatechin, epicatechin gallate, epigallocatechin, and epigallocatechin gallate) were tested for their ability to inhibit tube formation in vitro using a model in which human microvascular endothelial cells were exposed to a constant rate of a physiologically low level of H2O2. In this model, the production of interleukin (IL)-8 by human microvascular endothelial cells at a low level of H2O2 was required for angiogenesis, as assessed by tube formation in three-dimensional gel in culture. Vitamin E (d-alpha-tocopherol, 40 microM) in the culture media significantly reduced IL-8 production and angiogenesis. Among the green tea catechins, epigallocatechin (0.5-1 microM) was the most effective in reducing IL-8 production and inhibiting angiogenesis. These results suggest that consumption of green tea catechins or supplemental intake of vitamin E may have preventive effects on tumor development, mediated, at least in part, through inhibition of angiogenesis via suppression of IL-8 production.
Tang
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Vascular Biology Laboratory, JM USDA-Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.
Meydani
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D002392:Catechin / Q000494:pharmacology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D016209:Interleukin-8 / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D008833:Microcirculation; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D018384:Oxidative Stress; D013662:Tea / Q000737:chemistry*; D024502:alpha-Tocopherol / Q000494:pharmacology*
D016209:Interleukin-8; D013662:Tea; D002392:Catechin; D006861:Hydrogen Peroxide; D024502:alpha-Tocopherol