The BCR/ABL tyrosine kinase induces production of reactive oxygen species in hematopoietic cells

The BCR/ABL oncogene causes chronic myelogenous leukemia, a myeloproliferat ive disorder characterized by clonal expansion of hematopoietic progenitor cells and myeloid cells, It is shown here that transformation of the hemato poietic cell lines Ba/F3, 32Dcl3, and M07e with BCR/ABL results in an incre ase in reactive oxygen species (ROS) compared with quiescent, untransformed cells. The increase in ROS was directly due to BCR/ABL because it was bloc ked by the ABL-specific tyrosine kinase inhibitor STI571, Oxidative stress through ROS is believed to have many biochemical effects, including the pot ential ability to inhibit protein-tyrosine phosphatases (PTPases), To under stand the significance of increased production of ROS, a model system was e stablished in which hydrogen peroxide (H2O2) was added to untransformed cel ls to mimic the increase in ROS induced constitutively by BCR/ABL. H2O2 sub stantially reduced total cellular PTPase activity to a degree approximately equivalent to that of pervanadate, a well known PTPase inhibitor. Further, stimulation of untransformed cells with H2O2 or pervanadate increased tyro sine phosphorylation of each of the most prominent known substrates of BCR/ ABL, including c-ABL, c-CBL, SHC, and SHP-2. Treatment of the BCR/ABL-expre ssing cell line MO7/p210 with the reducing agents pyrrolidine dithiocarbama te or N-acetylcysteine reduced the accumulation of ROS and also decreased t yrosine phosphorylation of cellular proteins. Further, treatment of M07e ce lls with H2O2 or pervanadate increased the tyrosine kinase activity of c-AB L, Drugs that alter ROS metabolism or reactivate PTPases may antagonize BCR /ABL transformation.