title: Unconventional rapid Erk1,2 activation is indispensable for proliferation of the growth factor-independent myeloid leukemic cell line KG1.
abstract: While normal hematopoietic progenitor cells are dependent on colony-stimulating factors for in vitro proliferation, myeloid leukemic cells are frequently factor-independent. In this study we investigated several signalling intermediates of the Ras-Er1,2 pathway which may be involved in the development of growth factor independence. In the growth factor independent cell line KG1, an extremely short activation pattern of Erk1,2 with a maximum at 30 s was observed in response to FBS. In contrast, stimulation of the IL-3 receptor in AML193 cells resulted in a transient Erk activation peaking at 5 min and returning to base levels after 15 min. Although the Erk activation in KG1 cells is short-lived, using the MEK inhibitor PD98059, we demonstrated that Erk phosphorylation is essential for proliferation of these cell lines. We also detected major differences in Shc phosphorylation between factor-dependent and -independent cells. These data suggest that Erk activation is essential for proliferation of growth factor-dependent and -independent leukemic cells. The minimal Erk activation observed in KG1 cells in response to serum is sufficient for mitogenesis of these cells.
authors.affiliation: Department of Hematology, University Medical Centre, Leiden, The Netherlands.
authors.forename: R M
authors.initials: RM
authors.lastname: Barge
authors.forename: J
authors.initials: J
authors.lastname: Dorrestijn
authors.forename: J H
authors.initials: JH
authors.lastname: Falkenburg
authors.forename: R
authors.initials: R
authors.lastname: Willemze
authors.forename: J A
authors.initials: JA
authors.lastname: Maassen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology* / Q000502:physiology; D007951:Leukemia, Myeloid / Q000201:enzymology* / Q000473:pathology*; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D011493:Protein Kinase C / Q000172:deficiency / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000502:physiology; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000096:biosynthesis / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007377:Interleukin-3; D011506:Proteins; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one