Transfection of a vector expressing wild-type p53 into cells of two human glioma cell lines enhances radiation toxicity.
Replication-deficient adenovirus (Adv5)-based vectors containing either wild-type p53 or the beta-gal marker gene were introduced into cells of the T98G (p53 mutant) and U87MG (p53 wild-type) human glioma cell lines. The wild-type p53 gene was successfully expressed in each cell line as shown by flow cytometry and Western blotting. The presence of the p53-expressing vector was toxic in both cell lines compared to control cells or to those containing the beta-gal vector. At levels of Adv5p53 vector that produced detectable toxicity, the effect of irradiation was enhanced, producing a twofold increase in cell killing. In the T98G cells, the presence of the p53 vector resulted in an increase in the number of cells undergoing apoptosis after irradiation, whereas a smaller and only additive response was observed in the U87MG cells. Conversely, an increase in micronucleus formation, indicating corrupt mitotic activity, was observed in irradiated Adv5p53-positive U87MG cells but not in T98G cells. These data suggest that p53-expressing vectors effectively enhance radiation lethality in these human glioma cell lines, but that the mechanism of action cannot be simply related to activation of the p53-dependent pathway to apoptosis.
Geng
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Loyola-Hines Department of Radiotherapy, Cancer Center #338, Maywood, Illinois 60153, USA.
Walter
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Melian
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Vaughan
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AT
D017209:Apoptosis / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004249:DNA Damage; D004273:DNA, Neoplasm / Q000378:metabolism / Q000528:radiation effects; D005822:Genetic Vectors; D005910:Glioma / Q000235:genetics / Q000378:metabolism / Q000532:radiotherapy*; D006801:Humans; D048629:Micronuclei, Chromosome-Defective / Q000528:radiation effects; D011836:Radiation Tolerance / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000528:radiation effects; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*
D004273:DNA, Neoplasm; D016159:Tumor Suppressor Protein p53