OBJECTIVETo study the effect and molecular mechanism of epigallocatechin-3-gallate (EGCG) on epithelial-mesenchymal transition (EMT) in vitro induced by human recombinant TGF-β1 protein in squamous cell carcinoma of the head and neck.

METHODSEMT morphological changes of Tu686 cells were observed after sequential treatment of 5 ng/ml TGF-β1 and 20 µmol/L EGCG. Tu686 cells were collected after the treatment of 5 ng/ml TGF-β1 for 24 h and EGCG with different concentrations (0, 10, 20, 30 µmol/L) for another 24 h or 20 µmol/L EGCG treatment for different time phase (6, 12, 24 h). Then RT-PCR and Western-blot were applied to detect mRNA and protein expression level of epithelial cell marker E-cadherin, mesenchymal cell marker Vimentin and Smad7, an inhibit molecule of TGF-β1 mediated pathway in Tu686 cells.

RESULTSTGF-β1 successfully induced characterized EMT morphological and molecular changes in Tu686 cells, in which expression of E-cadherin decreased, Vimentin increased and Smad7 declined. However, EGCG could reverse the TGF-β1 mediated process of EMT by downregulating the expression of Vimentin and upregulating the expression of E-cadherin and Smad7.

CONCLUSIONEGCG significantly inhibits TGF-β1-mediated EMT inTu686 cell lines of SCCHN, which maybe associated with the upregulated-expression of Smad7, an inhibitor in TGF-β1 signaling pathway.