hygromycin-a and Osteosarcoma

Topics: Animals; Base Composition; Base Sequence; Cinnamates; Dogs; Drug Resistance; Gene Expression; Genes, Viral; Genetic Vectors; Gentamicins; Hygromycin B; Molecular Sequence Data; Mutation; Osteosarcoma; Polymerase Chain Reaction; Proviruses; Restriction Mapping; Retroviridae; Transfection; Tumor Cells, Cultured; Virus Replication

Mutations of the gene encoding p53, a 53-kilodalton cellular protein, are found frequently in human tumor cells, suggesting a crucial role for this gene in human oncogenesis. To model the stepwise mutation or loss of both p53 alleles during tumorigenesis, a human osteosarcoma cell line, Saos-2, was used that completely lacked endogenous p53. Single copies of exogenous p53 genes were then introduced by infecting cells with recombinant retroviruses containing either point-mutated or wild-type versions of the p53 cDNA sequence. Expression of wild-type p53 suppressed the neoplastic phenotype of Saos-2 cells, whereas expression of mutated p53 conferred a limited growth advantage to cells in the absence of wild-type p53. Wild-type p53 was phenotypically dominant to mutated p53 in a two-allele configuration. These results suggest that, as with the retinoblastoma gene, mutation of both alleles of the p53 gene is essential for its role in oncogenesis.

Topics: Alleles; Base Sequence; Cinnamates; Cloning, Molecular; DNA; Drug Resistance; Genes, p53; Genetic Vectors; Humans; Hygromycin B; Molecular Sequence Data; Moloney murine leukemia virus; Mutation; Neomycin; Osteosarcoma; Plasmids; Transfection; Tumor Cells, Cultured