Up Regulation Of Peroxiredoxin 2 Which Is Correlated With Disappearance Of Philadelphia Chromosome In CML Cells Might Have Therapeutic Applications During Imatinib Therapy

BCR/ABL oncogenic tyrosine kinase is known to induce high levels of intracellular ROS which may further induce genomic instability with malignant transformation and even imatinib (IM) resistance. There are several lines of evidence that the production of reactive oxygen species (ROS) and the expression and activity of antioxidant enzymes make up the primary redox control of leukemia cells and cell survival. Therapies targeting the redox environment such as over-expression of antioxidants or antioxidant treatment, could inhibit tumor cell growth even resistant cells. In this study, we investigated the change of peroxiredoxin (Prx), which have a function of protection against oxidative stress, and survival of BCR-ABL positive cells during IM therapy.

BCR-ABL1 positive cell lines were cultured using 20% IMDM medium. We evaluated cell growth by MTT assay, and also evaluated BCR/ABL expression by western blot analysis. We also evaluated changes of intracellular ROS level and antioxidant enzymes, by immunoblot assay. siRNAs against Prx2 (100-200nM) were transfected into K562 cells using HiPerFect transfection Reagent (Qiagen) according to manufacturers’ protocol. During siRNA transfection, 1uM of imatinib was treated for 48hours. 72 hours after siRNA transfection, expression of BCR/ABL and Prx2 were detected by western blot assay and proliferation was determined by MTT assay method. Intracellular ROS was measured by flow cytometry after 10uM DCF-DA staining for 20mins.

During IM treatment, we observed the significant decrease of cell viability and decrease of intracellular ROS level in BCR-ABL1 positive cell lines. These finding were well correlated with eradication of BCR/ABL oncogene by western blot results. The expression levels of Prx2 was restored with IM treatment and restoration of redox enzymes is correlated with reduction of BCR-ABL protein in Philadelphia positive cells. siRNAs transfected cells were not decreased cell survival even though eradication of BCR/ABL oncogene during IM treatment.

Significant change of ROS and Prx2 levels according to IM treatment are closely correlated with bcr/abl kinase level in both BCR-ABL1 positive cell lines. This finding was correlated with restoration of the level of PRX2. Those results has been implicated the possibility of therapeutic application by modulation redox system. Strategy of over-expression of Prx2 might be able to control sensitivity of the BCR-ABL1 positive cells to drug-induced apoptosis. Understanding the molecular mechanisms of changes on ROS and redox enzymes may be potential tools to develop more potent new drugs in Ph+ CML or Ph+ ALL patients especially for IM resistant.

No relevant conflicts of interest to declare.