Epicatechin-3-gallate reverses TGF-β1-induced epithelial-to-mesenchymal transition and inhibits cell invasion and protease activities in human lung cancer cells

Epithelial-to-mesenchymal transition (EMT) and invasion potential have been considered as essential factors in cancer metastasis, which is the major cause of cancer death. EMT is a multi-step process that involves gain invasion, cytoskeleton change, cell adhesion, and proteolytic extracellular matrix degradation. Epicatechin-3-gallate (ECG), which is a natural polyphenolic component of green tea, elicits several antioxidant and anti-inflammatory effects. However, the effects of ECG on cancer invasion and EMT of human lung carcinoma remain unknown. We provided molecular evidence supporting the anti-metastatic effect of ECG. This compound suppressed the invasion (P < 0.001) of highly metastatic A549 cells by reducing the activities of matrix metalloproteinase-2 (P < 0.001) and urokinasetype plasminogen activator (P < 0.001). ECG also reversed the transforming growth factor (TGF)-β1-induced EMT and upregulated epithelial markers, such as E-cadherin. Conversely, ECG inhibited mesenchymal markers, such as fibronectin and p-FAK. The subcutaneous inoculation of this compound also inhibited the tumor growth of the A549 cells in vivo. Therefore, ECG may be used as an anti-cancer and anti-invasion agent for the adjuvant treatment and metastasis control of human lung cancer cells. ECG may also be administered as an effective chemopreventive agent against TGF-β1-induced EMT.