MUTATIONAL INACTIVATION OF THE P53 GENE IN THE HUMAN ERYTHROID LEUKEMIC K562 CELL-LINE

The K562 human chronic myelogenous leukemia (CML) cell line has attain ed widespread use as a model for studying hematologic malignancy and e rythroid differentiation. Sequencing of the p53 gene in the K562 cell line demonstrated a mutation in exon 5 characterized by a single base insertion (cytosine) between codons 135 and 136. This frameshift mutat ion leads to an N-terminal truncated protein of 147 amino acids. Only the mutated sequence was present suggesting that the normal allele has been lost. Reverse transcription PCR (RT-PCR) detected a p53 transcri pt but Western blotting and immunohistochemical staining of cells fail ed to detect p53 protein. The identification of an inactivation mutati on of p53 in the K562 cell line further supports the argument that p53 mutations play a role in myeloid blast transformation of CML.