Role of NAD(P)H:quinone oxidoreductase 1 on tumor necrosis factor-alpha-induced migration of human vascular smooth muscle cells.

OBJECTIVES In a preliminary study, NAD(P)H:quinone oxidoreductase 1 (NQO1) was found to be highly expressed in cultured human aortic smooth muscle cells (HASMC) and dicumarol, a NQO1 inhibitor and a coumarin-derived natural anticoagulant, suppressed tumor necrosis factor (TNF)-alpha-induced HASMC migration. Therefore, it was hypothesized that NQO1 plays an important role in the regulation of vascular smooth muscle cells (VSMC) migration activated by TNF-alpha. METHODS AND RESULTS Gelatin zymography, reporter gene, electrophoretic mobility shift and Western blotting assays showed that dicumarol, but not other coumarin-derived anticoagulants, inhibited TNF-alpha-induced HASMC migration and suppressed TNF-alpha-induced matrix metalloproteinase (MMP)-9 expression and secretion in a dose-dependent manner. In addition, down-regulation of NQO1 by transfection of its small interfering RNA similarly inhibited TNF-alpha-induced MMP-9 secretion, indicating that dicumarol-mediated inhibition of MMP-9 expression is due in large part to inhibition of NQO1. Down-regulation of NQO1 inhibits MMP-9 gene expression by suppressing activation of nuclear factor-kappa B (NF-kappaB) and activator protein-1 (AP-1), well-known key elements mediating MMP-9 gene expression in its promoter, via the p38 MAPK and JNK pathways. CONCLUSION The results of the present study demonstrate that down-regulation of NQO1 effectively suppresses TNF-alpha-induced HASMC migration through inhibition of MMP-9 expression, suggesting that NQO1 may be a potential target for the prevention of vascular disorders related to migration of VSMC.