In vitro transformation of Li-Fraumeni syndrome fibroblasts by SV40 large T antigen mutants

Transfection of SV40 early region DNA into normal human diploid fibroblasts (NHDFs) increases their proliferative potential to a limited extent. We have investigated the roles of the SV40 large T antigen (LTAg) regions responsible for binding to the protein products of the retinoblastoma (Rb) and p5...

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Bibliographic Details
Published inOncogene Vol. 9; no. 3; p. 719
Main Authors Maclean, K, Rogan, E M, Whitaker, N J, Chang, A C, Rowe, P B, Dalla-Pozza, L, Symonds, G, Reddel, R R
Format Journal Article
LanguageEnglish
Published England 01.03.1994
Subjects
Antigens, Polyomavirus Transforming - genetics
Base Sequence
Cell Transformation, Viral
Cellular Senescence
DNA Primers
Fibroblasts
Genes, p53
Humans
Li-Fraumeni Syndrome - pathology
Molecular Sequence Data
Mutation
Sequence Deletion
Transfection
Tumor Cells, Cultured
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Summary:Transfection of SV40 early region DNA into normal human diploid fibroblasts (NHDFs) increases their proliferative potential to a limited extent. We have investigated the roles of the SV40 large T antigen (LTAg) regions responsible for binding to the protein products of the retinoblastoma (Rb) and p53 genes in this temporary escape from senescence. Patients encoding LTAg mutants were transfected into NHDFs and into Li-Fraumeni syndrome (LFS) fibroblasts which are heterozygous wild-type (wt)/null-mutant for p53. A LTAg mutated in the p53-binding region (T402DE) had greatly reduced efficiency of focus formation, and a p110Rb-binding mutant was unable to induce any foci. T402DE-induced NHDF foci senesced at the same time as untransfected cells, but the equivalent LFS foci all had increased proliferative potentials, with the greatest increase being seen in clones that lost the wt p53 allele. One LFS clone expressed the T402DE mutant during focus formation, but later lost both the T402DE DNA and the wt p53 allele. We conclude that SV40-induced focus formation in NHDFs requires the LTAg p110Rb-binding region, and is enhanced by loss of normal p53 function. In contrast, increased proliferative potential is primarily due to loss of p53 function.
ISSN:0950-9232