The presence of p53 transformation-related protein in Ab-MuLV transformed cells is required for their development into lethal tumors in mice.

p53, a cellular-encoded protein, is synthesized at elevated levels in a wide range of tumor cells. Ab-MuLV-transformed cells expressing both the viral-encoded p120 oncogene and the cellular-encoded p53 display a lethal tumor phenotype in syngeneic mice. L12 is an exceptional Ab-MuLV-transformed cell line that expresses the p120 oncogene and lacks the p53 cellular protein. Injection of L12 cells into syngeneic mice is followed by the development of local tumors that are subsequently rejected. Prolonged treatment of L12 cells with TPA, a tumor cell promoter, gave rise to L12T cells that synthesize the p53 protein and exhibit a lethal tumor phenotype. Comparison of one-dimensional proteolytic partial peptide map of p53 obtained from L12T to that obtained from other Ab-MuLV-transformed cell lines confirmed their identity. These results suggest a correlation between the cellular expression of p53 in Ab-MuLV-transformed cells and their capacity to develop into lethal tumors in syngeneic mice.