Activation of matrix metalloproteinase-2 by overexpression of manganese superoxide dismutase in human breast cancer MCF-7 cells involves reactive oxygen species

Matrix metalloproteinases (MMPs) participate in cell migration and remodeling processes by affecting the extracellular matrix. MMP-2 is thought to be involved in cancer cell invasiveness. It has been proposed that the activity of MMP-2 can be modulated by intracellular reactive oxygen species (ROS)/reactive nitrogen species. We hypothesized that manganese superoxide dismutase (MnSOD) could mediate MMP-2 activity by changing the intracellular ROS level and that nitric oxide (NO) may be involved in this process. Human breast cancer MCF-7 cells were stably transfected with plasmids containing MnSOD cDNA. A 2-30-fold increase of MnSOD protein and activity was observed in four clones. Our data demonstrated that overexpression of MnSOD stimulated the activation of MMP-2 with a corresponding elevation of ROS. A decrease in ROS by ebselen, a glutathione peroxidase mimetic, or by transduction of adenovirus containing human catalase or glutathione peroxidase cDNA abolished the effect of MnSOD on MMP-2 activation. Treatment of MCF-7 cells with antimycin A or rotenone increased intracellular ROS production and MMP-2 activation simultaneously. Our data also showed a suppression of endothelial nitric-oxide synthase expression that was accompanied by decreased (NO)-N-. production in MnSOD-overexpressing cells. However, the changes in endothelial nitric-oxide synthase and (NO)-N-. did not correlate with the MnSOD activity. Corresponding changes of MMP-2 activity after the addition of a NOS inhibitor (N-G--amino-L-arginine) or a (NO)-N-. donor ((Z)-1-[(2-aminoethyl) -N-(2-ammonioethyl) amino]diazen-1-ium-1,2-diolate) to the cells suggested the possibility that (NO)-N-. may be involved in the MnSOD-mediated MMP2 activation pathway. These results indicate that MnSOD induces MMP-2 activity by regulation of intracellular ROS and imply that signaling pathways involving (NO)-N-. may also be involved in the MnSOD mediation of MMP-2 activity.