title: Activating mutations of the c-kit proto-oncogene in a human mast cell leukemia cell line.
abstract: The c-kit proto-oncogene encodes a receptor tyrosine kinase that is known to play a crucial role in mast cell growth and differentiation. In a human mast cell leukemia cell line (HMC-1), KitR was found to be constitutively phosphorylated on tyrosine, activated and associated with phosphatidylinositol 3-kinase (P13K) in the absence of autocrine production of SCF. Sequencing of c-kit cDNA revealed that c-kit genes of HMC-1 cells were composed of a normal, wild-type allele and a mutant allele with two point mutations in codon 560 and codon 816, resulting in intracellular amino acid substitutions of Gly-560 for Val and Val-816 for Asp, respectively. Murine c-kit mutants encoding Gly-559 and/or Val-814, corresponding to human Gly-560 and/or Val-816, were constructed by site-directed mutagenesis and expressed in cells of a human embryonic kidney cell line (293T). In the transfected cells, KitR (Gly-559 + Val-814) and KitR (Val-814) were strikingly phosphorylated on tyrosine and activated in the absence of SCF, whereas tyrosine phosphorylation and activation of KitR (Gly-559) or wild-type KitR was modest or little, respectively. These results suggest that constitutive activation of KitR in HMC-1 results from the activating mutations of c-kit gene, and raise the possibility that the activating mutations, particularly at codon 814 of murine c-kit or at codon 816 of human c-kit, may participate in oncogenesis of mast cells.
authors.affiliation: Department of Internal Medicine II, Osaka University Medical School, Suita, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kanakura
authors.forename: T
authors.initials: T
authors.lastname: Furitsu
authors.forename: T
authors.initials: T
authors.lastname: Tsujimura
authors.forename: J H
authors.initials: JH
authors.lastname: Butterfield
authors.forename: L K
authors.initials: LK
authors.lastname: Ashman
authors.forename: H
authors.initials: H
authors.lastname: Ikeda
authors.forename: H
authors.initials: H
authors.lastname: Kitayama
authors.forename: Y
authors.initials: Y
authors.lastname: Kanayama
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuzawa
authors.forename: Y
authors.initials: Y
authors.lastname: Kitamura
mesh_terms: D006801:Humans; D007946:Leukemia, Mast-Cell / Q000235:genetics*; D009154:Mutation; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019009:Proto-Oncogene Proteins c-kit; D011519:Proto-Oncogenes; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D016184:Receptors, Colony-Stimulating Factor / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D016184:Receptors, Colony-Stimulating Factor; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases