Oral Administration of EGCG, a Green Tea Antioxidant, Reduces Growth and Capillary Density of Melanoma but does not affect those of the Heart and Skeletal Muscles in Mice

Abstract

We previously reported that EGCG, a green tea antioxidant, inhibits tumor growth and angiogenesis of breast cancer in mice. However, it is not clear whether EGCG exerts an anti‐angiogenic effect on normal body tissues while inhibiting tumor angiogenesis. The present study evaluates the effects of EGCG on melanoma angiogenesis and growth, capillary density (CD) in the heart and skeletal muscles of mice. Six wk old male mice (C57BL/6J) were given EGCG at 50‐100 mg/kg/d (25 mg/50 ml in drinking water) for 4 wks. Control mice received drinking water only. In the 2nd wk, 10^6 B16F10 (mouse melanoma) cells were injected in the right proximal dorsal. In the end, the tumor, heart, and limb muscles were isolated for measuring tumor size, CD using CD31 immunohistochemistry, and VEGF expression using ELISA. EGCG significantly reduced tumor weight over the control (2.9±0.5 vs. 5.9±1.8 g; n=6; P<0.05), CD (117±21 vs. 167±25; P<0.01), and VEGF expression (32.6±1.6 vs. 41.5±2.3 pg/mg; P<0.01) of the melanomas in mice. EGCG had no effect on CD in the heart (3270±162 vs. 3103±226 #/mm^2) and limb muscles (370±55 vs. 381±44 #/mm^2), compared to the control (P>0.05). EGCG did not affect VEGF expression in the heart and limb muscles, the body weight and heart weight. These findings support the hypothesis that EGCG as an antioxidant inhibits tumor angiogenesis and tumor growth but does not affect the normal tissue CD and growth. (HL51971 & AA013821)