Adaptation of human leukemia HL-60 cells to hydrogen peroxide as oxidative stress

The growth inhibitory effect on human leukemia HL-60 cells of hydrogen peroxide as an oxidative stress and the possibility of adaptation of the cells to this stress were examined. When HL-60 cells were treated with various concentrations of hydrogen peroxide, concentrations of 5-200 microM were found to be sublethal. When HL-60 cells were repeatedly exposed to 50 and 100 microM hydrogen peroxide, they began to grow stably in the medium with the drug after a few months, indicating that they had become adapted to the drug. Sublines HP50-2 and HP100-1 cloned from these cultures were approximately 40-fold and 340-fold more resistant, respectively, than the parent cells. These resistant sublines tended to form cell aggregates in stationary culture, suggesting an alteration in their surface membrane. The HP50-2 and HP100-1 lines will be useful in the studies of many cellular mechanisms associated with reactive oxygens.