Relationship between oxidative stress and imatinib resistance in model chronic myeloid leukemia cells

Chronic myeloid leukemia (CML) develops due to the presence of the BCR‐ABL1 protein, a target of tyrosine kinase inhibitors (TKIs), such as imatinib (IM), used in a CML therapy. CML eradication is a challenge due to developing resistance to TKIs. BCR‐ABL1 induces endogenous oxidative stress leading to genomic instability and development of TKI resistance. Model CML cells susceptible or resistant to IM, as well as wild‐type, non‐cancer cells without the BCR‐ABL1 protein were treated with IM, hydrogen peroxide (H2O2) as a model trigger of external oxidative stress, or with IM+H2O2. Accumulation of reactive oxygen species (ROS), DNA damage, activity of selected antioxidant enzymes and glutathione (GSH), and mitochondrial potential (MMP) were assessed. We observed increase in ROS accumulation in BCR‐ABL1 positive cells and distinct levels of ROS accumulation in IM‐susceptible cells when compared to IM‐resistant ones, as well as increased DNA damage caused by IM action in sensitive cells. Depletion of GSH levels and a decreased activity of glutathione peroxidase (GPx) in the presence of IM was higher in the cells susceptible to IM. IMresistant cells showed an increase of catalase activity and a depletion of MMP. BCR‐ABL1 kinase alters ROS metabolism, and IM resistance is accompanied by the changes in activity of GPx, catalase, and alterations in MMP.