Cell lines and clinical isolates derived from Ph1-positive chronic myelogenous leukemia patients express c-abl proteins with a common structural alteration.
The Philadelphia chromosome (Ph1), observed in greater than 90% of chronic myelogenous leukemia (CML) patients, results from a specific chromosomal translocation involving the c-abl gene. The translocation breakpoint occurs near c-abl and correlates with the production of an altered c-abl mRNA. In the CML-derived cell line K562, Ph1 is accompanied by a structurally altered c-abl protein (P210c-abl) with in vitro tyrosine kinase activity not detected with the normal c-abl protein (P145c-abl). We have examined c-abl proteins in other Ph1-positive CML cell lines and found that they all express P210c-abl. P210c-abl was also detected in bone marrow cells from CML patients with Ph1 in the accelerated and blast crisis phases of the disease. Comparison of the [35S]methionine-labeled tryptic peptides generated from the normal P145c-abl and P210c-abl showed that they have closely related structures, but additional polypeptide sequences are present in P210c-abl. Based on these results we propose that translocation of c-abl in Ph1-positive CML results in the creation of a chimeric gene leading to the production of a structurally altered c-abl protein with activated tyrosine kinase activity. The altered P210 c-abl protein is strongly implicated in the pathogenesis of CML.
D002460:Cell Line; D002678:Chimera; D002904:Chromosomes, Human, 21-22 and Y; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics*; D009857:Oncogenes; D011494:Protein Kinases / Q000235:genetics; D011505:Protein-Tyrosine Kinases; D014178:Translocation, Genetic
D009363:Neoplasm Proteins; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases