Publication Date:
2012-11-16
Description:
Abstract 3528 Background: Unsuccessful treatment of pediatric precursor B acute lymphoblastic leukemia (ALL) can be ascribed to cellular resistance to antileukemic drugs. In particular, resistance towards prednisolone is associated with poor prognosis in pediatric ALL. For three reasons, we hypothesized that anti-apoptosis sustained by the BCL2 family member MCL1 and glycolysis are linked processes and concomitantly induce resistance to prednisolone: 1) Glycolysis and apoptosis are closely related survival pathways both associated with prednisolone resistance, 2) Increased glucose metabolism has been directly linked to MCL1 stabilization and attenuation of apoptosis, and 3) BCL2 family members can adjust oxidative phosphorylation, a process that together with anaerobic glycolysis, is responsible for cellular respiration and ATP production. In this study, we functionally determined the synergistic contribution of MCL1 and glycolysis to prednisolone resistance in childhood ALL. Methods: Leukemic cells of pediatric ALL patients, 〉90% blasts, were treated in vitro with prednisolone for 48 hours. Changes in MCL1 protein levels were measured by reverse phase protein array. MCL1 knockdown was achieved by locked nucleic acid oligonucleotides (LNAs) and lentiviral silencing in two different prednisolone resistant leukemic cell lines, and the effect was assessed with RTQ-PCR and Western blot. Cell viability and cell count were analyzed by MACSQuant. Glucose consumption was measured using the GAGO20 glucose assay, in which glucose is oxidized to form the spectrophotometric end-product Oxidized o-Dianisidine. 2-deoxyglucose (2DG) was used to inhibit glycolysis. Cytotoxicity of prednisolone in leukemic cells was determined by the in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) drug-resistance assay. Sensitivity and resistance to prednisolone was assessed using previously established LC50 cut-off values, shown to be linked to the prognosis of patients. Results: MCL1 protein expression decreased by 2.9-fold after in vitro prednisolone treatment in prednisolone sensitive patients' leukemic cells (p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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