p53-induced up-regulation of MnSOD and GPx but not catalase increases oxidative stress and apoptosis.
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.
Hussain
S Perwez
SP
Laboratory of Human Carcinogenesis, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland 20892-4255, USA.
Amstad
Paul
P
He
Peijun
P
Robles
Ana
A
Lupold
Shawn
S
Kaneko
Ichiro
I
Ichimiya
Masato
M
Sengupta
Sagar
S
Mechanic
Leah
L
Okamura
Shu
S
Hofseth
Lorne J
LJ
Moake
Matthew
M
Nagashima
Makoto
M
Forrester
Kathleen S
KS
Harris
Curtis C
CC
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
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