Tumor gelatinases and invasion inhibited by the green tea flavanol epigallocatechin-3-gallate

Abstract

BACKGROUND Given the association of consumption of green tea with prevention of cancer development, metastasis, and angiogenesis, the effect of the main flavanol present, epigallocatechin‐3‐gallate (EGCG), on two gelatinases most frequently overexpressed in cancer and angiogenesis (MMP‐2 and MMP‐9) and on tumor cell invasion and chemotaxis were examined. METHODS Zymography, Western blotting, and enzyme linked immuoadsorbent assay were used to analyze the effect of EGCG on MMP‐2 and MMP‐9 activity, whereas its effect on tumor cell invasion and chemotaxis was examined using modified Boyden chamber assays. RESULTS A Zn²⁺ chelation‐independent, dose‐dependent, noncompetitive inhibition by EGCG of both gelatinases was found at concentrations 500 times lower than that reported to inhibit urokinase. Tumor cell invasion of a reconstituted basement membrane matrix, but not chemotaxis, was reduced by 50% with EGCG concentrations equivalent to that in the plasma of moderate green tea drinkers, and 2 orders of magnitude below those of tissue inhibitors of MMPs. Although higher concentrations of EGCG were associated with increased levels of both cell‐associated gelatinases and their activator MT1‐MMP, no increased gelatinase activation was found, and TIMP‐1 and TIMP‐2 inhibitors were up‐regulated. Finally, concentrations of EGCG active in restraining proliferation and inducing apoptosis of transformed cells were more than 100 times lower than those reported for normal cells. CONCLUSIONS Epigallocatechin‐3‐gallate is a potent inhibitor of gelatinases and an orally available pharmacologic agent that may confer the antiangiogenic and antimetastatic activity associated with green tea. Cancer 2001;91:822–32. © 2001 American Cancer Society.