Mechanisms of chemotherapy failure in refractory/relapsed acute myeloid leukemia: the role of cytarabine resistance and mitochondrial metabolism.

Acute myeloid leukemia (AML) is an aggressive hematological malignancy. Patients with wild-type FLT3 relapsed or refractory (R/R) AML face significant therapeutic challenges due to the persistent lack of effective treatments. A comprehensive understanding of the mechanisms underlying chemotherapy resistance is needed to the development of effective treatment strategies. Therefore, we investigated the molecular mechanisms underlying cytarabine (Ara-C) resistance and daunorubicin (DNR) tolerance in Ara-C-resistant RHI-1 cells derived from the wild-type FLT3 AML cell line SHI-1. Quantitative analysis of intracellular drug concentrations, proteomics, and phosphoproteomics showed that DNR resistance in Ara-C-resistant RHI-1 cells is driven by metabolic remodeling toward mitochondrial metabolism, upregulation of DNA repair pathways, and enhanced reactive oxygen species (ROS) detoxification rather than reduced drug uptake. Moreover, targeting these compensatory mechanisms, particularly the OXPHOS complex I proteins, significantly improved the efficacy of both Ara-C and DNR. Conclusively, these findings highlight mitochondrial metabolism and DNA repair as critical factors in chemotherapy resistance and offer valuable insights into potential therapeutic targets for enhancing treatment outcomes in patients with wild-type FLT3 R/R AML.