Induction of apoptosis in p53-deficient human hepatoma cell line by wild-type p53 gene transduction: inhibition by antioxidant.
We investigated the role of wild-type (wt)-p53 as an inducer of apoptotic cell death in human hepatoma cell lines. Following the retrovirus-mediated transduction of the wt-p53 gene, Hep3B cells lacking the endogenous p53 expression began to die through apoptosis in 4 h. They showed a maximal apoptotic death at 12 h, whereas HepG2 cells expressing endogenous p53 did not. However, the transduction of the wt-p53 gene elicited growth suppression of both Hep3B and HepG2 cells. P21(WAF1/CIP1), a p53-inducible cell cycle inhibitor, was induced, not only in Hep3B cells undergoing apoptosis, but also in HepG2 cells. The kinetics of the p21(WAF1/CIP1) induction, DNA fragmentation, and growth suppression of the Hep3B cells showed that DNA fragmentation and growth suppression progressed rapidly following p21(WAF1/CIP1) accumulation. N-acetyl-cysteine or glutathione, potent antioxidants, strongly inhibited the DNA fragmentation, but did not reduce the elevated level of p21(WAF1/CIP1). These findings suggested that p21(WAF1/CIP1) was not a critical mediator for the execution of p53-mediated apoptosis, although it contributed to the growth inhibition of cells undergoing apoptosis. Furthermore, p53-mediated apoptosis could be repressed by antioxidants.
Lee
K H
KH
Laboratory of Molecular Oncology, Korea Cancer Center Hospital, Seoul.
Kim
K C
KC
Jung
Y J
YJ
Ham
Y H
YH
Jang
J J
JJ
Kwon
H
H
Sung
Y C
YC
Kim
S H
SH
Han
S K
SK
Kim
C M
CM
D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular; D002470:Cell Survival; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D053938:DNA Fragmentation; D016166:Free Radical Scavengers / Q000494:pharmacology; D016158:Genes, p53; D005978:Glutathione / Q000494:pharmacology; D006801:Humans; D020287:In Situ Nick-End Labeling; D008113:Liver Neoplasms; D012190:Retroviridae / Q000235:genetics / Q000378:metabolism; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D000975:Antioxidants; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D016166:Free Radical Scavengers; D016159:Tumor Suppressor Protein p53; D018844:Cyclin-Dependent Kinases; D005978:Glutathione; D000111:Acetylcysteine