title: Prolonged activation of the mitogen-activated protein kinase pathway is required for macrophage-like differentiation of a human myeloid leukemic cell line.
abstract: The role of the mitogen-activated protein kinase (MAPK) signal transduction pathway in the proliferation of mammalian cells has been well established. However, there are relatively few reports concerning cell differentiation being mediated by MAPK. The effect of phorbol 12-myristate 13-acetate (PMA) on cell differentiation and signal transduction in a human myeloid leukemia cell line, TF-1a, was investigated. When TF-1a cells were treated with 10(-6), 10(-7), 10(-8), and 10(-9) M PMA for 24 h, they underwent 98, 93, 91, and 51% macrophage-like differentiation, respectively. PMA treatment rapidly (10 min) induced phosphorylation of MAPK kinase (MEK and p44/42 MAPK), which persisted for at least 24 h. p44/42 MAPK immunoprecipitates from lysates of PMA-treated cells had increased ability to phosphorylate the transcription factor Elk-1. This is important because phosphorylated Elk-1 can be considered an "end-product" of the MAPK pathway. In contrast, treatment of TF-1a cells with granulocyte/macrophage-colony stimulating factor induced only transient activation of MEK and p44/42 MAPK (10-20 min) and an increase (approximately 50%) in cell proliferation, without any change in cellular differentiation. These results suggest that macrophage-like differentiation may be dependent on prolonged activation of the MAPK pathway. Additional support for this conclusion was obtained from experiments showing that treatment of TF-1a cells with antisense oligonucleotides for MEK1 coding sequences prior to adding PMA inhibited macrophage-like differentiation. Furthermore, transient transfection with an inactive, dominant-negative MEK mutant also inhibited PMA-induced differentiation, whereas transient transfection with a plasmid coding for constitutively activated MEK led to macrophage-like differentiation in the absence of PMA.
authors.affiliation: Department of Internal Medicine, University of South Florida and H. Lee Moffitt Cancer Center and Research Institute, Tampa 33612, USA. hu@moffitt.usf.edu
authors.forename: X
authors.initials: X
authors.lastname: Hu
authors.forename: L C
authors.initials: LC
authors.lastname: Moscinski
authors.forename: N I
authors.initials: NI
authors.lastname: Valkov
authors.forename: A B
authors.initials: AB
authors.lastname: Fisher
authors.forename: B J
authors.initials: BJ
authors.lastname: Hill
authors.forename: K S
authors.initials: KS
authors.lastname: Zuckerman
mesh_terms: D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D016373:DNA, Antisense / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D007951:Leukemia, Myeloid / Q000473:pathology / Q000503:physiopathology*; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014157:Transcription Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D050807:ets-Domain Protein Elk-1
chemical_list: D016373:DNA, Antisense; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C494112:ELK1 protein, human; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D013755:Tetradecanoylphorbol Acetate