Epigallocatechin gallate (EGCG) is known to impair adhesion of various types of tumor cells to extracellular matrix proteins such as fibronectin and laminin by binding to fibronectin and laminin. However, it is not clear whether the direct binding of EGCG to tumor cells causes a similar impairment. In this study, we examined whether EGCG prevents tumor cells from adhering to fibronectin by binding to a fibronectin receptor, β1 integrin. Human fibrosarcoma HT-1080 cells were incubated with EGCG at various concentrations. After being washed with serum-free cell culture medium, they were plated onto fibronectin-coated wells, and the adhesion activity was examined. The results showed that the pre-treatment with EGCG inhibited cells from adhering to fibronectin in a dose-dependent manner. Cell extracts were then loaded onto an EGCG-immobilized agarose gel column and the bound fractions were examined by enzyme-linked immunoassay and Western blotting using anti-integrin β1 antibody. The results indicated that integrin β1 was bound by the column, demonstrating the interaction between integrin β1 and EGCG. These results suggest that EGCG prevents HT-1080 cells from adhering to fibronectin by impairing interaction between the cells and integrin β1.
2006 by The Pharmaceutical Society of Japan