title: Analysis of synergism between stem cell factor and granulocyte-macrophage colony-stimulating factor on human megakaryoblastic cells: an increase in tyrosine phosphorylation of 145 kDa subunit of c-kit in two-factor combination.
abstract: In normal hematopoiesis, stem cell factor (SCF) stimulates survival, proliferation and differentiation of hematopoietic progenitors. Although SCF acts synergistically with a variety of cytokines, the mechanism of growth factor-cooperation remains to be determined. To analyze the synergism between SCF and granulocyte-macrophage colony-stimulating factor (GM-CSF), we established a new megakaryoblastic cell line, HML-2, by culture in the presence of both SCF and GM-CSF. While SCF alone or GM-CSF alone supported modest cell growth, SCF and GM-CSF together induced substantial growth of this cell line. SCF alone tyrosine-phosphorylated several bands including the 145 kDa subunit of c-kit. GM-CSF alone did not cause the tyrosine phosphorylation of the 145 kDa subunit, but markedly up-regulated the expression of the 145 kDa subunit of c-kit. The combination of SCF and GM-CSF resulted in a synergistic increase in tyrosine phosphorylation of the 145 kDa subunit of c-kit. Several proliferation inhibitors which removed the two-factor interaction on the growth of the HML-2 cells down-regulated the 145 kDa subunit of c-kit. Thus, a synergistic increase in tyrosine phosphorylation of the 145 kDa subunit of c-kit may be one possible mechanism underlying the cooperation of SCF and GM-CSF on the HML-2 cell growth.
authors.affiliation: Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kamijo
authors.forename: K
authors.initials: K
authors.lastname: Koike
authors.forename: K
authors.initials: K
authors.lastname: Takeuchi
authors.forename: T
authors.initials: T
authors.lastname: Higuchi
authors.forename: N
authors.initials: N
authors.lastname: Sawai
authors.forename: T
authors.initials: T
authors.lastname: Kikuchi
authors.forename: H
authors.initials: H
authors.lastname: Tsumura
authors.forename: H
authors.initials: H
authors.lastname: Akiyama
authors.forename: T
authors.initials: T
authors.lastname: Koike
authors.forename: E
authors.initials: E
authors.lastname: Ishii
authors.forename: A
authors.initials: A
authors.lastname: Komiyama
mesh_terms: D015153:Blotting, Western; D004357:Drug Synergism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D007947:Leukemia, Megakaryoblastic, Acute / Q000378:metabolism*; D046911:Macromolecular Substances; D009363:Neoplasm Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D019089:Stem Cell Factor / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D009363:Neoplasm Proteins; D019089:Stem Cell Factor; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019009:Proto-Oncogene Proteins c-kit