p53-induced up-regulation of MnSOD and GPx but not catalase increases oxidative stress and apoptosis

Cancer Res. 2004 Apr 1;64(7):2350-6. doi: 10.1158/0008-5472.can-2287-2.

Abstract

p53-mediated apoptosis may involve the induction of redox-controlling genes, resulting in the production of reactive oxygen species. Microarray expression analysis of doxorubicin exposed, related human lymphoblasts, p53 wild-type (WT) Tk6, and p53 mutant WTK1 identified the p53-dependent up-regulation of manganese superoxide dismutase (MnSOD) and glutathione peroxidase 1 (GPx). Consensus p53 binding sequences were identified in human MnSOD and GPx promoter regions. A 3-fold increase in the MnSOD promoter activity was observed after the induction of p53 in Li-Fraumeni syndrome (LFS) fibroblast, TR9-7, expressing p53 under the control of a tetracycline-regulated promoter. An increased protein expression of endogenous MnSOD and GPx also positively correlated with the level of p53 induction in TR9-7 cells. However, catalase (CAT) protein expression remained unaltered after p53 induction. We also examined the expression of MnSOD, GPx, and CAT in a panel of normal or LFS fibroblasts, containing either WT or mutant p53. We found increased MnSOD enzymatic activity, MnSOD mRNA expression, and MnSOD and GPx protein in LFS fibroblasts carrying a WT p53 allele when compared with homozygous mutant p53 isogenic cells. The CAT protein level was unchanged in these cells. We observed both the release of cytochrome C and Ca(2+) from the mitochondria into the cytoplasm and an increased frequency of apoptotic cells after p53 induction in the TR9-7 cells that coincided with an increased expression of MnSOD and GPx, and the level of reactive oxygen species. The increase in apoptosis was reduced by the antioxidant N-acetylcysteine. These results identify a novel mechanism of p53-dependent apoptosis in which p53-mediated up-regulation of MnSOD and GPx, but not CAT, produces an imbalance in antioxidant enzymes and oxidative stress.

MeSH terms

  • Apoptosis / physiology*
  • Calcium / metabolism
  • Catalase / biosynthesis
  • Cell Line
  • Cytochromes c / metabolism
  • Doxorubicin / pharmacology
  • Enzyme Induction
  • Fibroblasts / enzymology
  • Gene Expression Regulation, Enzymologic / physiology
  • Glutathione Peroxidase / biosynthesis*
  • Glutathione Peroxidase / genetics
  • Glutathione Peroxidase / metabolism
  • Humans
  • Mitochondria / metabolism
  • Oxidative Stress / physiology
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Reactive Oxygen Species / metabolism
  • Superoxide Dismutase / biosynthesis*
  • Superoxide Dismutase / genetics
  • Superoxide Dismutase / metabolism
  • Tumor Suppressor Protein p53 / antagonists & inhibitors
  • Tumor Suppressor Protein p53 / biosynthesis
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / physiology*
  • Up-Regulation / physiology

Substances

  • RNA, Messenger
  • Reactive Oxygen Species
  • Tumor Suppressor Protein p53
  • Doxorubicin
  • Cytochromes c
  • Catalase
  • Glutathione Peroxidase
  • Superoxide Dismutase
  • Calcium