Binding interaction between (-)-epigallocatechin gallate causes impaired spreading of cancer cells on fibrinogen.

Green tea and tea catechins, especially (-)-epigallocatechin gallate (EGCG), have been shown to have various health benefits including anti-cancer, anti-metastasis, and anti-cardiovascular disease effects. Our previous studies demonstrated that three plasma proteins, fibronectin, histidine-rich glycoprotein, and fibrinogen were bound by EGCG, and that one specific domain in fibronectin was responsible for its binding interaction with EGCG. Fibrinogen consists of 6 chains linked by the disulfide bonds of two each of the α-, β-, and γ-chains. The present study examined whether fibrinogen had a specific domain interacting with EGCG. The results of affinity chromatography under reducing conditions demonstrated that each of the α-, β-, and γ-subunit chains of fibrinogen was bound by EGCG. We also demonstrated that several peptides generated by treatment with cyanogen bromide or thermolysin were bound by EGCG. The amino acid sequences analyzed revealed that these peptides included those derived from the α-, β-, and γ-chains of fibrinogen. EGCG inhibited the spreading of mouse metastatic LL2-Lu3 lung cancer cells on the fibrinogen substratum, which suggested an impairment in the interaction between cancer cells and fibrinogen. Since the interaction between cancer cells and fibrinogen plays an important role in metastasis, the present results suggest, at least partially, that EGCG inhibited metastasis in the mouse models reported previously by inhibiting such an interaction.