Inhibitory effect of esculetin on migration, invasion and matrix metalloproteinase-9 expression in TNF-α-induced vascular smooth muscle cells

Esculetin, a potent non-competitive inhibitor of lipoxygenase, has been shown to inhibit vascular smooth muscle cell (VSMC) proliferation. However, the effect of esculetin on the matrix metalloproteinase-9 (MMP-9) regulation responsible for cell migration and invasion has not been previously investigated. The results of the present study showed the esculetin (12.5-25 mu g/ml) induced the inhibition of migration and invasion in tumor necrosis factor-alpha (TNF-alpha-treated VSMC, as demonstrated by a matrigel invasion assay and wound healing analysis. However, esculetin did not affect cell viability in TNF-alpha-treated VSMC under 0-25 mu g/ml concentration conditions. In addition, both zymographic and immunoblot experiments showed that esculetin suppressed the TNF-alpha-induced expression of MMP-9 in VSMC in a dose-dependent manner. Furthermore, the treatment of cells with esculetin decreased the activity of the TNF-alpha-induced MMP-9 promoter, which was driven by a luciferase reporter. Finally, esculetin reduced the binding activities of nuclear factor-kappa B (NF-kappa B) and activator protein-1 (AP-1), which are cis-elements present in the promoter of the MMP-9 gene, in TNF-alpha-treated VSMC. Taken together, these results demonstrated that esculetin decreased the migration and invasion of cells by suppressing MMP-9 expression, which subsequently reduced the binding activities of NF-kappa B and AP-1 in TNF-alpha-treated VSMC. These novel findings provide basic information for effective therapeutic treatment with esculetin for atherosclerotic disease.