title: Apoptotic efficacy of etomoxir in human acute myeloid leukemia cells. Cooperation with arsenic trioxide and glycolytic inhibitors, and regulation by oxidative stress and protein kinase activities.
abstract: Fatty acid synthesis and oxidation are frequently exacerbated in leukemia cells, and may therefore represent a target for therapeutic intervention. In this work we analyzed the apoptotic and chemo-sensitizing action of the fatty acid oxidation inhibitor etomoxir in human acute myeloid leukemia cells. Etomoxir caused negligible lethality at concentrations up to 100 µM, but efficaciously cooperated to cause apoptosis with the anti-leukemic agent arsenic trioxide (ATO, Trisenox), and with lower efficacy with other anti-tumour drugs (etoposide, cisplatin), in HL60 cells. Etomoxir-ATO cooperation was also observed in NB4 human acute promyelocytic cells, but not in normal (non-tumour) mitogen-stimulated human peripheral blood lymphocytes. Biochemical determinations in HL60 cells indicated that etomoxir (25-200 µM) dose-dependently inhibited mitochondrial respiration while slightly stimulating glycolysis, and only caused marginal alterations in total ATP content and adenine nucleotide pool distribution. In addition, etomoxir caused oxidative stress (increase in intracellular reactive oxygen species accumulation, decrease in reduced glutathione content), as well as pro-apoptotic LKB-1/AMPK pathway activation, all of which may in part explain the chemo-sensitizing capacity of the drug. Etomoxir also cooperated with glycolytic inhibitors (2-deoxy-D-glucose, lonidamine) to induce apoptosis in HL60 cells, but not in NB4 cells. The combined etomoxir plus 2-deoxy-D-glucose treatment did not increase oxidative stress, caused moderate decrease in net ATP content, increased the AMP/ATP ratio with concomitant drop in energy charge, and caused defensive Akt and ERK kinase activation. Apoptosis generation by etomoxir plus 2-deoxy-D-glucose was further increased by co-incubation with ATO, which is apparently explained by the capacity of ATO to attenuate Akt and ERK activation. In summary, co-treatment with etomoxir may represent an interesting strategy to increase the apoptotic efficacy of ATO and (with some limitations) 2-deoxy-D-glucose which, although clinically important anti-tumour agents, exhibit low efficacy in monotherapy.
authors.affiliation: Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain.
authors.forename: María Cristina
authors.initials: MC
authors.lastname: Estañ
authors.affiliation: Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Calviño
authors.affiliation: Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain; Departamento de Biología de Sistemas, Unidad de Bioquímica y Biología Molecular, Facultad de Medicina y Ciencias de la Salud, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.
authors.forename: Susana
authors.initials: S
authors.lastname: Calvo
authors.affiliation: Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Guillén-Guío
authors.affiliation: Departamento de Biología de Sistemas, Unidad de Bioquímica y Biología Molecular, Facultad de Medicina y Ciencias de la Salud, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.
authors.forename: María Del Carmen
authors.initials: Mdel C
authors.lastname: Boyano-Adánez
authors.affiliation: Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: de Blas
authors.affiliation: Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Rial
authors.affiliation: Centro de Investigaciones Biológicas (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, Madrid, Spain.
authors.forename: Patricio
authors.initials: P
authors.lastname: Aller
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D003847:Deoxyglucose / Q000627:therapeutic use*; D004852:Epoxy Compounds / Q000627:therapeutic use*; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D007191:Indazoles / Q000627:therapeutic use; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy*; D018384:Oxidative Stress / Q000187:drug effects; D010087:Oxides / Q000627:therapeutic use*; D011494:Protein Kinases / Q000187:drug effects
chemical_list: D001152:Arsenicals; D004852:Epoxy Compounds; D007191:Indazoles; D010087:Oxides; D003847:Deoxyglucose; D011494:Protein Kinases; C054207:etomoxir; D000077237:Arsenic Trioxide; C016371:lonidamine