Publication Date:
2010-11-19
Description:
Abstract 4456 Background. The plant-derived agent α-bisabolol is a small oily sesquiterpene alcohol that has been demonstrated to be cytotoxic against human malignant non-hematological and leukemic cells (Bonifacio M et al, Blood, 2009 ASH annual meeting abstracts;114:4800). Here we tested its activity against BCR-ABL+ cell lines and primary cells from patients, alone or in combination with the Tyrosine-Kinase Inhibitors (TKIs) Imatinib and Nilotinib. Also, the mechanism of α-bisabolol cytotoxicity in BCR-ABL+ cells was assessed. Methods. We used the BCR-ABL+ K562, LAMA-84 and CML-T1 cell lines and primary leukemic cells from 14 patients with BCR-ABL+ Acute Lymphoblastic Leukemia at diagnosis. First, the citotoxicity of single-agent α-bisabolol was determined by MTT. Then, mitochondrial membrane potential of treated cells was evaluated by the JC-1 dye in flow cytometry and fluorescence microscopy. Permeabilized leukemic cells were assayed for oxygen consumption by measuring mitochondrial state 3 and uncoupled respiration. Reactive oxygen species (ROS) production in α-bisabolol treated cells were quantified in flow cytometry by oxidation of CM-H2DCFDA, measuring the fluorescence intensity of the DCF products. Apoptosis was studied by the poly(ADP-ribose) polymerase (PARP) cleavage and internucleosomal DNA laddering analysis. Finally, the combination effects between α-bisabolol and Imatinib or Nilotinib (kindly provided by Novartis) were analyzed according to the median-effect method of Chou and Talalay using the CalcuSyn software. Results. α-bisabolol reduced the viability of BCR-ABL+ cells in a dose-dependent manner. The mean IC50 values of α-bisabolol were 46±11 μ M for primary leukemic cells and ranged from 62 to 115 μ M in the cell lines. JC-1 staining of BCR-ABL+ primary leukemic cells treated with 40 μ M α-bisabolol for 3 to 5 hours demonstrated a dissipation of the mitochondrial transmembrane potential (ΔΨm), thus indicating the start of the apoptotic process. Moreover, NADH-supported state 3 respiration in α-bisabolol treated leukemic cells was significantly decreased in comparison with untreated leukemic controls (140.0±70.5 vs 280.7±11.9 pmol O2/min/106 cells; p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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