Inhibition of the mutant p53 gene in transformation assays.
Mutation of the p53 gene is a key element in the development of several human cancers. Intron 4, a noncoding region of the p53 gene, is required for optimal expression of that gene. We have previously shown that nuclear protein binds intron 4 and have defined the protein-binding site. In this paper we address the question, "Does the mutant p53 gene's ability to transform cells to the malignant phenotype depend on protein binding to intron 4?" Using an in vitro assay in which the mutant p53 gene and Ha-ras oncogene cooperate in transformation of cells to the malignant phenotype, we determined the ability of mutant mouse p53 gene constructs, with and without two base pair substitutions at the intron 4 protein-binding site, to participate in malignant transformation. On Day 1, 5 x 10(5) rat embryo fibroblasts were transfected by the calcium phosphate procedure with 10 micrograms of both a mutant p53 gene construct and Ha-ras oncogene. Malignant transformation was evidenced by the formation of discrete foci of heaped-up cells. After 14 days of incubation at 37 degrees C in DMEM and 10% fetal calf serum (8% CO2), the cells were stained with cresyl violet and the foci counted. In three separate experiments, the presence of two base pair substitutions at the intron 4 protein-binding site caused a significant decrease in the number of foci formed (P less than 0.05).
Beenken
S W
SW
Department of Surgery, University of Alabama, Birmingham 35294.
Raycroft
L
L
Lozano
G
G
D000818:Animals; D001482:Base Composition; D001665:Binding Sites; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D005347:Fibroblasts / Q000502:physiology; D005796:Genes; D007438:Introns; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats
D011506:Proteins