Many epidemiological studies have suggested that consumption of
green tea may decrease the risk of
cancer. The chemopreventive effect of
green tea polyphenols (
GTP) has been demonstrated through the inhibition of cell proliferation and angiogenesis in cell culture and animal models of
breast cancer.
Metastasis of
breast cancer is the major reason for the high mortality of
breast cancer patients and is directly linked to the invasive behavior of
breast cancer cells.
Cancer metastasis consists of several interdependent processes including
cancer cell adhesion,
cancer cell migration, and invasion of
cancer cells. In this study, we evaluated the effect of
GTP on human
breast cancer cells, and we show that in addition to inhibiting cell growth,
GTP also suppressed the invasive behavior of MDA-MB-231 cells. These anti-invasive effects of
GTP were the result of the inhibition of constitutively active
transcription factors AP-1 and
NF-kappaB, which further suppressed secretion of
urokinase plasminogen activator (uPA) from
breast cancer cells. Based on these results, it can be hypothesized that
GTP treatment resulted in the inhibition of formation of signaling complexes responsible for cell adhesion and migration (uPA, uPA
receptor, vitronectin,
integrin receptor) and cell invasion (uPA, uPA receptor). Our results indicate that
GTP may contribute to the anticancer effects of
green tea by inhibiting the invasive behavior of
cancer cells.