The p21WAF1/CIP1 promoter is methylated in rat-1 cells:: Stable restoration of p53-dependent p21WAF1/CIP1 expression after transfection of a genomic clone containing the p21WAF1/CIP1 gene
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Allan, LA
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Imperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, EnglandImperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, England
Allan, LA
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Duhig, T
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Imperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, EnglandImperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, England
Duhig, T
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Read, M
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Imperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, EnglandImperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, England
Read, M
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Fried, M
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Imperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, EnglandImperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, England
Fried, M
[1
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[1] Imperial Canc Res Fund, Eukaryot Gene Org & Express Lab, London WC2A 3PX, England
Rat-1 cells are used in many studies on transformation, cell cycle, and apoptosis. whereas UV treatment of Rat-1 cells results in apoptosis. X-ray treatment does not induce either apoptosis or a cell cycle block. X-ray treatment of Rat-1 cells results in both an increase of p53 protein and expression of the p53-inducible gene MDM2 but not the protein or mRNA of the p53-inducible p21(WAF1/CIP1) gene, which in other cells plays an important role in p53-mediated cell cycle block. The lack of p21(WAF1/CIP1) expression appears to be the result of hypermethylation of the p21(WAF1/CIP1) promoter region, as p21(WAF1/CIP1) protein expression could be induced by growth of Rat-1 cells in the presence of 5-aza-2-deoxycytidine. Furthermore, sequence analysis of bisulfite-treated DNA demonstrated extensive methylation of cytosine residues in CpG dinucleotides in a CpG-rich island in the promoter region of the p21(WAF1/CIP1) gene. Stable X-ray-induced p53-dependent p21(WAF1/CIP1) expression and cell cycle block were restored to a Rat-1 clone after transfection with a P1 artificial chromosome (PAC) DNA clone containing a rat genomic copy of the p21(WAF1/CIP1) gene. The absence of expression of the p21(WAF1/CIP1) gene may contribute to the suitability of Rat-1 cells for transformation, cell cycle, and apoptosis studies.