title: Phorbol ester-induced mononuclear cell differentiation is blocked by the mitogen-activated protein kinase kinase (MEK) inhibitor PD98059.
abstract: The purpose of this study was to evaluate whether the mitogen-activated protein kinase (MAPK) signaling pathway contributes to 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mononuclear differentiation in the human myeloblastic leukemia ML-1 cells. Upon TPA treatment, the activity of ERK1 and ERK2 rapidly increased, with maximal induction between 1 and 3 h, while ERK2 protein levels remained constant. The activity of JNK1 was also significantly induced, with JNK1 protein levels increasing moderately during exposure to TPA. Treatment of cells with PD98059, a specific inhibitor of mitogen-activated protein kinase kinase (MEK), inhibited TPA-induced ERK2 activity. Furthermore, PD98059 completely blocked the TPA-induced differentiation of ML-1 cells, as assessed by a number of features associated with mononuclear differentiation including changes in morphology, nonspecific esterase activity, phagocytic ability, NADPH oxidase activity, mitochondrial respiration, and c-jun mRNA inducibility. We conclude that activation of the MEK/ERK signaling pathway is necessary for TPA-induced mononuclear cell differentiation.
authors.affiliation: Department of Environmental Health Sciences, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland 21205, USA.
authors.forename: H
authors.initials: H
authors.lastname: He
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Gorospe
authors.forename: N J
authors.initials: NJ
authors.lastname: Holbrook
authors.forename: M A
authors.initials: MA
authors.lastname: Trush
mesh_terms: D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D007963:Leukocytes, Mononuclear / Q000166:cytology* / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D008934:Mitogens / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D012333:RNA, Messenger; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D008934:Mitogens; D047428:Protein Kinase Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D013755:Tetradecanoylphorbol Acetate; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one