(−)-Epigallocatechin-3-gallate promotes pro-matrix metalloproteinase-7 production via activation of the JNK1/2 pathway in HT-29 human colorectal cancer cells

Abstract

Matrix metalloproteinase (MMP)-7 (matrilysin-1) plays significant roles in the growth, invasion, and metastasis of colorectal tumors, while (−)-epigallocatechin-3-gallate (EGCG), a green tea polyphenol with chemopreventive properties, has been shown to be an inhibitor of MMP-2 and MMP-9. In the present study, HT-29 human colorectal cancer cells were treated with EGCG to examine its effects on pro-MMP-7 induction and production using RT–PCR and western blot analyses. Surprisingly, EGCG (10–100 μM) treatment increased both intracellular and extracellular pro-MMP-7 protein levels (2.6–8.4-fold and 1.9–6.4-fold, respectively) in dose- and time-dependent manner, with a significant upregulation of its mRNA expression. EGCG also activated extracellular signal-regulated protein kinase (ERK)1/2, c-JUN NH ₂ -terminal kinase (JNK)1/2 and p38 mitogen-activated protein kinase (MAPK), as previously reported. In addition, the polyphenol triggered the phosphorylation of c-JUN (Ser63 and Ser73) and induced c-JUN/c-FOS, thereby increasing the DNA binding activity of activator protein-1 (AP-1), as shown by an AP-1 luciferase reporter assay. Pharmacological blockade of MAPK activities suggested that pro-MMP-7 expression was induced via JNK1/2 activation, but not in the case of ERK1/2 or p38 MAPK. N -Acetyl- l -cysteine, superoxide ( \(\mathrm{O}_{2}^{{-}}\) ) dismutase and catalase attenuated the EGCG-induced pro-MMP-7 production, suggesting an involvement of oxidative stress in these events. Conversely, EGCG spontaneously generated \(\mathrm{O}_{2}^{{-}}\) in a cell-free system that utilized a cytochrome C reduction method. Further, (−)-epicatechin-3-gallate (25 and 100 μM) and green tea polyphenols (33 and 132 μg/ml) induced pro-MMP-7 expression, whereas (−)-epicatechin and (−)-epigallocatechin (100 μM each) did not. Induction of pro-MMP-7 expression by EGCG was also shown in another human colorectal adenocarcinoma cell line, Caco-2. Our results suggest that some green tea catechins induce pro-MMP-7 production via \(\mathrm{O}_{2}^{{-}}\) production and the activation of JNK1/2, c-JUN, c-FOS and AP-1 in HT-29 cells.