title: p53-induced up-regulation of MnSOD and GPx but not catalase increases oxidative stress and apoptosis.
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.
authors.affiliation: Laboratory of Human Carcinogenesis, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland 20892-4255, USA.
authors.forename: S Perwez
authors.initials: SP
authors.lastname: Hussain
authors.forename: Paul
authors.initials: P
authors.lastname: Amstad
authors.forename: Peijun
authors.initials: P
authors.lastname: He
authors.forename: Ana
authors.initials: A
authors.lastname: Robles
authors.forename: Shawn
authors.initials: S
authors.lastname: Lupold
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kaneko
authors.forename: Masato
authors.initials: M
authors.lastname: Ichimiya
authors.forename: Sagar
authors.initials: S
authors.lastname: Sengupta
authors.forename: Leah
authors.initials: L
authors.lastname: Mechanic
authors.forename: Shu
authors.initials: S
authors.lastname: Okamura
authors.forename: Lorne J
authors.initials: LJ
authors.lastname: Hofseth
authors.forename: Matthew
authors.initials: M
authors.lastname: Moake
authors.forename: Makoto
authors.initials: M
authors.lastname: Nagashima
authors.forename: Kathleen S
authors.initials: KS
authors.lastname: Forrester
authors.forename: Curtis C
authors.initials: CC
authors.lastname: Harris
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002374:Catalase / Q000096:biosynthesis; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology; D004790:Enzyme Induction; D005347:Fibroblasts / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D005979:Glutathione Peroxidase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin; D045304:Cytochromes c; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D002118:Calcium