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.

Nyckelord

Alleles

Animals

Apoptosis

Cell Transformation, Viral

Gene Deletion

Gene Expression Regulation, Neoplastic

Genes, myc

Genes, p53

Lymphoma, T-Cell

Mice

Moloney murine leukemia virus

Mutagenesis, Insertional

Recombinant Fusion Proteins

Transfection

Tumor Cells, Cultured

Tumor Suppressor Protein p53

Virus Integration

Publikations- och innehållstyp

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ref (ämneskategori)