Tumor suppression by manganese superoxide dismutase: A novel function of MnSOD? A commentary

Manganese superoxide dismutase (MnSOD) is a nuclear-encoded primary antioxidant enzyme in the mitochondria. The known function of MnSOD is to remove superoxide radicals generated in the mitochondria. Given the recent explosion of evidence linking the role of MnSOD to the suppression of cancer, it has been proposed that MnSOD might function as a new type of tumor suppressor gene. Considering the role of free radicals in carcinogenesis, the significance of oxidative stress in the mitochondria, and the involvement of MnSOD in tumor suppression, the author proposes a reconciliation of the antioxidant function of MnSOD with its tumor suppression function. The focus of this report is to present some of the evidence supporting this idea.