Reconstitution of wild-type p53 expression triggers apoptosis in a p53-negative v-myc retrovirus-induced T-cell lymphoma line.
Inactivation or mutation of the p53 tumor suppressor gene has been observed in a wide variety of human and murine tumors. We have found that a v-myc retrovirus (J3)-induced T-cell lymphoma line (J3D) has lost one of its p53 alleles, whereas the other has become inactivated due to the insertion of a Moloney murine leukemia provirus in intron 4 with an opposite transcriptional orientation. No p53 protein could be detected by immunoprecipitation with monoclonal anti-p53 antibodies. We have transfected this line with the temperature-sensitive murine Val135 construct that is expressed as mutant p53 at 37 degrees C and largely wild-type p53 at 32 degrees C. There was no difference in the number of viable cells among the p53 transfectants, the parental cells, and neomycin vector-transfected control cells at 37 degrees C. Following a temperature shift to 32 degrees C, the p53 transfectants rapidly lost viability, and 95-100% of the cells were dead by 3 days, whereas the control cells remained unaffected. Examination of DNA isolated from p53-transfected cells grown at 32 degrees C revealed nucleosomal fragmentation, indicating cell death by apoptosis. It is suggested that apoptosis is triggered by contradictory signaling. Constitutively expressed v-myc can stimulate cell proliferation, whereas expression of wild-type p53 in cells that have lost endogenous p53 expression in the course of their neoplastic development may suppress growth.
Wang
Y
Y
Department of Tumor Biology, Karolinska Institute, Stockholm, Sweden.
Ramqvist
T
T
Szekely
L
L
Axelson
H
H
Klein
G
G
Wiman
K G
KG
D000483:Alleles; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D002472:Cell Transformation, Viral; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D016259:Genes, myc; D016158:Genes, p53; D016399:Lymphoma, T-Cell / Q000473:pathology*; D051379:Mice; D008979:Moloney murine leukemia virus / Q000235:genetics; D016254:Mutagenesis, Insertional; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000502:physiology*; D016662:Virus Integration
D011993:Recombinant Fusion Proteins; D016159:Tumor Suppressor Protein p53