Metabolic characteristics of imatinib resistance in chronic myeloid leukaemia cells.

BACKGROUND AND
PURPOSE: Early detection of resistance development is crucial for imatinib-based treatment in chronic myeloid leukaemia (CML) patients. We aimed to distinguish metabolic markers of cell resistance to imatinib. EXPERIMENTAL APPROACH: Two human imatinib-sensitive CML cell lines: LAMA84-s and K562-s, and their resistant counterparts: LAMA84-r and K562-r (both resistant to 1 microM imatinib), and K562-R (5 microM) were analysed by nuclear magnetic resonance spectroscopy to assess global metabolic profiling, including energy state, glucose and phospholipid metabolism. KEY
RESULTS: We found, by Western blotting and flow cytometry, that the levels of Bcr-Abl tyrosine kinase and multi-drug resistance p-glycoprotein were inconsistent among resistant clones. On the other hand, phospholipid metabolism and lactate production were highly predictive for cell response to imatinib. As previously reported, sensitive cells showed significantly decreased glycolytic activity (lactate) and phospholipid synthesis (phosphocholine) as well as increased phospholipid catabolism (glycerophosphocholine) after 24 h of 1 microM imatinib treatment, which correlated with inhibition of cell proliferation and induction of apoptosis. In contrast to their sensitive counterparts, the K562-r, K562-R and LAMA84-r maintained increased phospholipid synthesis and glycolytic lactate production in the presence of 1 microM (K562-r and LAMA84-r) and 5 microM (K562-R) imatinib. CONCLUSIONS AND IMPLICATIONS: Specific metabolic markers for early detection of imatinib resistance, including increased glycolytic activity and phospholipid turnover, can be identified in resistant clones. Once validated in human isolated leukocytes, they may be used to monitor the responsiveness of CML patients to treatment.