cDNA microarray analysis of endothelial cells in response to green tea reveals a suppressive phenotype

Green tea may prevent cancer, partially by inhibiting tumor angiogenesis. Our previous studies showed that green tea extract was effective in inhibiting breast cancer and endothelial cell proliferation in vitro, and suppressed xenograft size and decreased the tumor vessel density in vivo. Here, we set out to further investigate the molecular mechanisms of this observed angiogenesis suppression. We utilized cDNA microarray technology to profile the global changes in endothelial cellular gene expression in response to green tea. HUVEC (human umbilical vein endothelial cells) were exposed in vitro to green tea for either 6 or 48 h. Only statistically significantly differentially expressed genes were analyzed. Gene profiling demonstrated a global down-regulation of multiple genes involved in endothelial cell growth, signal transduction and oxidation, accompanied by up-regulation of several apoptotic genes. We validated these observations by showing positive correlations with biological assays of cellular proliferation, cell cycle, and apoptosis. The anti-oxidant characteristics of green tea and its metabolites were confirmed in the ORAC (oxygen radical absorbance capacity) assay. cDNA microarray revealed that green tea has an overall suppressive effect on multiple pathways in endothelial cells. This study contributes to the comprehensive analysis of the molecular effects of green tea on endothelial cells, and provides insight into genes that may be important in chemoprevention.