title: Monocytic differentiation of leukemic HL-60 cells induced by co-treatment with TNF-alpha and MK886 requires activation of pro-apoptotic machinery.
abstract: The block of hematopoietic differentiation program in acute myeloid leukemia cells can be overcome by differentiating agent like retinoic acid, but it has several side effects. A study of other differentiation signaling pathways is therefore useful to predict potential targets of anti-leukemic therapy. We demonstrated previously that the co-treatment of HL-60 cells with Tumor necrosis factor-alpha (TNF-alpha) (1 ng/mL) and inhibitor of 5-lipoxygenase MK886 (5 microm) potentiated both monocytic differentiation and apoptosis. In this study, we detected enhanced activation of three main types of mitogen-activated protein kinases (MAPKs) (p38, c-Jun amino-terminal kinase [JNK], extracellular signal-regulated kinase [ERK]), so we assessed their role in differentiation using appropriate pharmacologic inhibitors. The inhibition of pro-apoptotic MAPKs (p38 and JNK) suppressed the effect of MK886 + TNF-alpha co-treatment. On the other hand, down-regulation of pro-survival ERK pathway led to increased differentiation. Those effects were accompanied by increased activation of caspases in cells treated by MK886 + TNF-alpha. Pan-caspase inhibitor ZVAD-fmk significantly decreased both number of apoptotic and differentiated cells. The same effect was observed after inhibition of caspase 9, but not caspase 3 and 8. To conclude, we evidenced that the activation of apoptotic processes and pathways supporting apoptosis (p38 and JNK MAPKs) is required for the monocytic differentiation of HL-60 cells.
authors.affiliation: Department of Cytokinetics, Institute of Biophysics, Academy of Sciences of Czech Republic, vvi, Brno, Czech Republic.
authors.forename: Jirina
authors.initials: J
authors.lastname: Procházková
authors.forename: Lenka
authors.initials: L
authors.lastname: Stixová
authors.forename: Karel
authors.initials: K
authors.lastname: Soucek
authors.forename: Jirina
authors.initials: J
authors.lastname: Hofmanová
authors.forename: Alois
authors.initials: A
authors.lastname: Kozubík
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009000:Monocytes / Q000187:drug effects* / Q000473:pathology; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D002722:Chlorobenzenes
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D020169:Caspases; D015853:Cysteine Proteinase Inhibitors; D007211:Indoles; D016859:Lipoxygenase Inhibitors; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C060893:MK-886; D002722:Chlorobenzenes