Dihydroartemisinin Increases the Sensitivity of Acute Myeloid Leukemia Cells to Cytarabine via the Nrf2/HO-1 Anti-Oxidant Signaling Pathway

Background and Objective: In most cases of acute myeloid leukemia (AML), relapse frequently occurs due to chemoresistance. Modulating intracellular reactive oxygen species (ROS) levels may be a promising strategy to address the chemoresistance in AML. This study aimed to evaluate the potential of dihydroartemisinin (DHA) and its mechanism in improving the efficiency of cytarabine (Ara-C) in AML cells. Materials and Methods: After exposing HL-60 cells to Ara-C, DHA or their combination, the following analyses were carried out: CCK-8 assay for cell viability, the SynergyFinder tool for analyzing synergistic effect based CCK8 assay result, fluorometric assay with 2,7 -dichlorodihydrofluorescein for intracellular ROS levels, the flow cytometry for FITC/propidium iodide double staining and CD11b staining to investigate cell apoptosis and differentiation, western blot for the expression of Bax, Bcl-2, nuclear Nrf2 and HO-1 and Autodock tool assay for predicting the binding site of DHA. Results: The combination of Ara-C and DHA synergistically promoted the apoptosis and differentiation of HL-60 cells. Mechanistically, synergistic cytotoxic effects of Ara-C/DHA on HL-60 cells may be mediated by decreasing intracellular ROS levels. Combined with DHA blocked the activation of Nrf2/HO-1 anti-oxidant signaling caused by Ara-C. However, DHA only caused the down-regulation of HO-1, whereas the expression level of nuclear Nrf2 was unaffected. Molecular docking and Nrf2 transcriptional activity analysis revealed the effect of DHA is mediated by its suppression of Nrf2 transcriptional activity. Conclusion: The DHA can serve as an effective alternative in AML treatment, especially for patients exhibiting Ara-C resistance.