Raf-1 protein is required for growth factor-induced proliferation of hematopoietic cells.
Raf-1 is a 74-kD serine/threonine kinase located in the cell cytoplasm that is activated by phosphorylation in cells stimulated with a variety of mitogens and growth factors, including hematopoietic growth factors. Using c-raf antisense oligonucleotides to block Raf-1 expression, we have established that Raf-1 is required for hematopoietic growth factor-induced proliferation of murine cell lines stimulated by growth factors whose receptors are members of several different structural classes: (a) the hematopoietin receptor family, including interleukin (IL)-2, IL-3, IL-4, granulocyte colony-stimulating factor, granulocyte/macrophage colony-stimulating factor (GM-CSF), and erythropoietin; (b) the tyrosine kinase receptor class, including Steel factor and CSF-1; and (c) IL-6, leukemia inhibitory factor, and oncostatin M, whose receptors include the gp130 receptor subunit. Although results of previous experiments had suggested that IL-4 does not phosphorylate or activate the Raf-1 kinase, c-raf antisense oligonucleotides inhibited IL-4-induced proliferation of both myeloid and T cell lines, and IL-4 activated Raf-1 kinase activity in an IL-4-dependent myeloid cell line. In colony assays, c-raf antisense oligonucleotides completely inhibited colony formation of unseparated normal murine bone marrow cells stimulated with either IL-3 or CSF-1 and partially inhibited cells stimulated with GM-CSF. In addition, c-raf antisense oligonucleotides completely inhibited both IL-3- and GM-CSF-induced colony formation of CD34+ purified human progenitors stimulated with these same growth factors. Thus, Raf-1 is required for growth factor-induced proliferation of leukemic murine progenitor cell lines and normal murine and human bone marrow-derived progenitor cells regardless of the growth factor used to stimulate cell growth.
Muszynski
K W
KW
Biological Carcinogenesis and Development Program, Program Resources Inc./DynCorp, Frederick, Maryland 21702-1201, USA.
Ruscetti
F W
FW
Heidecker
G
G
Rapp
U
U
Troppmair
J
J
Gooya
J M
JM
Keller
J R
JR
D000818:Animals; D001483:Base Sequence; D001854:Bone Marrow Cells; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D004921:Erythropoietin / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology*; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006131:Growth Inhibitors / Q000494:pharmacology*; D006133:Growth Substances / Q000494:pharmacology*; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D015850:Interleukin-6; D007378:Interleukins / Q000494:pharmacology; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000494:pharmacology; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D053683:Oncostatin M; D010455:Peptides / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf; D011519:Proto-Oncogenes; D019089:Stem Cell Factor
D006131:Growth Inhibitors; D006133:Growth Substances; D016298:Hematopoietic Cell Growth Factors; D015850:Interleukin-6; D007378:Interleukins; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D008222:Lymphokines; C508351:OSM protein, human; D016376:Oligonucleotides, Antisense; C508352:Osm protein, mouse; D010455:Peptides; D011518:Proto-Oncogene Proteins; D019089:Stem Cell Factor; D053683:Oncostatin M; D004921:Erythropoietin; D016179:Granulocyte Colony-Stimulating Factor; D016173:Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D004247:DNA; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf