(-)-Epigallocatechin-3-gallate inhibits invasion and migration of salivary gland adenocarcinoma cells

(-)-Epigallocatechin-3-gallate (EGCG) has inhibitory effect on a variety of cancers by inducing apoptosis and cell cycle arrest or inhibiting angiogenesis and metastasis. EGCG has been found to induce apoptosis in salivary gland carcinoma cells, however, it is not known whether EGCG affects invasion and migration. Thus, this study was performed to clarify whether EGCG affects invasion and migration of salivary gland tumors. Matrigel invasion assay, wound scratch assay and migration assay using commercial kit were performed. beta 1 integrin expression and activation of its downstream molecules such as focal adhesion kinase (FAK), AKT and extracellular signal-regulated kinase (ERK) were examined by Western blot. Enzymatic activity of matrix metalloprotease (MMP)-2 and MMP-9 was examined by gelatin zymography. EGCG inhibited effectively invasion and migration of SGT cells in a dose-dependent manner. EGCG also inhibited the activation of beta 1 integrin-downstream molecules such as FAK, AKT and ERK as well as the expression of beta 1 integrin itself. Moreover, MMP-2 and MMP-9 expression and their enzymatic activity were reduced by EGCG in a dose-dependent manner. These results indicate that EGCG may effectively suppress salivary gland tumors by inhibiting metastasis through beta 1 integrin-mediated signaling.