Mv. Gurjar et al., Mechanism of inhibition of matrix metalloproteinase-9 induction by NO in vascular smooth muscle cells, J APP PHYSL, 91(3), 2001, pp. 1380-1386
Vascular smooth muscle (VSM) cell migration is a critical step in the devel
opment of a neointima after angioplasty. Matrix metalloproteinases (MMPs) d
egrade the basement membrane and extracellular matrix, facilitating VSM cel
l migration. Recently, we demonstrated that nitric oxide (NO) inhibits inte
rleukin-1 beta (IL-1 beta)-stimulated MMP-9 induction in rat aortic VSM cel
ls. In this study, we examined the hypothesis that NO inhibits MMP-9 induct
ion by attenuating superoxide generation and extracellular signal-regulated
kinase (ERK) activation. Stimulation of VSM cells with IL-1 beta significa
ntly (P<0.05) increased superoxide production, ERK activation, and MMP-9 in
duction. Pretreatment of VSM cells with the NO donor DETA NONOate significa
ntly (P<0.05) decreased IL-1 beta -stimulated superoxide generation. In add
ition, pretreatment of VSM cells with a specific ERK pathway inhibitor, PD-
98059, or DETA NONOate inhibited IL-1 beta -stimulated ERK activation and M
MP-9 induction. Direct exposure of VSM cells to increased superoxide levels
by treatment with xanthine/xanthine oxidase increased ERK activation and M
MP-9 induction, whereas pretreatment of cells with PD-98059 significantly (
P<0.05) inhibited xanthine/xanthine oxidase-stimulated ERK activation and M
MP-9 induction. We conclude that NO inhibits IL-1<beta>-stimulated MMP-9 in
duction by inhibiting superoxide generation and subsequent ERK activation.