Modulation of energy metabolism to overcome drug resistance in chronic myeloid leukemia cells through induction of autophagy

Abstract

Tyrosine kinase inhibitors (TKIs) such as imatinib (IM) are key drugs for treatment of chronic myeloid leukemia (CML). Development of drug resistance to TKIs due to BCR-ABL mutation, especially T315I mutation, poses a major challenge in the clinical treatment of CML. The purpose of this study was to test metabolic modulation as a potential strategy to overcome imatinib resistance based on the possible crosstalk between BCR-ABL signaling and metabolic changes in CML. 2-deoxy-d-glucose (2-DG) was used to modulate the glucose metabolism in CML cells sensitive to IM (KBM5 cell line) and resistant to imatinib with BCR-ABL T315I mutation (KBM5-T315I cell line). Seahorse XFe24 extracellular flux analyzer to quantify oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) was used to measure cellular energy metabolism. Cell proliferation was analyzed by CCK-8 assay and MTS assay. Annexin V/PI staining was used to evaluate cell apoptosis. Autophagy-related proteins and enzyme/proteins were detected by Western blotting. Cellular ATP concentration was detected using an ATP-based Cell Titer Kit. The combined action of 2-DG and IM was evaluated by calculating the drug combination index. Our results found that inhibition of glucose metabolism by 2-DG significantly impaired the viability of CML cells and co-treatment with 2-DG and imatinib induced a synergistic inhibition of KBM5 and KBM5-T315I cells. 2-DG induced cell death by autophagy, not by apoptosis, as evidenced by increased expression of Beclin1 and LC3AII and lack of annexin V/PI-positive cells. At the biochemical level, 2-DG inhibited glycolysis and mitochondrial oxygen consumption manifested by a significant decrease in ECAR and OCR, and a depletion of ATP. The severe metabolic stress induced by 2-DG in CML cells led to autophagic cell death. Our results suggested a metabolic vulnerability of CML cells that could be targeted by a combination of 2-DG and imatinib as an alternative treatment for imatinib-resistant CML.