v-Ha-RaS oncogene upregulates the 92-kDA type IV collagenase (MMP-9) gene by increasing cellular superoxide production and activating NF-kappa B

Matrix metalloproteinase 9 (MMP-9) degrades basement membrane type IV colla gen and is expressed during cellular migration and invasion. Here we show t hat v-Ha-Ras overexpression in rat kidney epithelial cells (REC) caused upr egulation of MMP-9 gene expression in part by increasing cellular oxidant l evels. v-Ha-Ras mediated the production of superoxide in Ras-transfected ce lls, which was associated with upregulated MMP-9 gene expression. Conversel y, v-Ha-Ras expression decreased steady-state levels of mRNAs from tissue i nhibitor of metalloproteinase I (TIMP-1), an inhibitor of MMP-9; plasminoge n activator inhibitor 1 (PAI-1), which indirectly activates MMP-9 by increa sing plasmin levels; and collagen IV, a substrate of MMP-9 and a major comp onent of basement membrane. Gel mobility shift assays demonstrated that Ras overexpression enhanced NF-kappaB, but not AP-1 DNA binding to motifs in t he MMP-9 gene promoter. The Ras-induced increase in NF-kappaB DNA binding c ould be inhibited by treatment with the antioxidants N-acetyl-L-cysteine an d glutathione monoester, suggesting that intracellular oxidant levels can m ediate MMP-9 transcription. Our findings identify an important role for Ras in the regulation of MMP-9 expression, and suggest that increased superoxi de production can upregulate MMP-9 expression and thus contribute to malign ant conversion. (C) 2001 Elsevier Science Inc.