title: Novel, activating KIT-N822I mutation in familial cutaneous mastocytosis.
abstract: OBJECTIVE
  We report the rare family in which cutaneous mastocytosis was diagnosed in the father and two children, with urticaria pigmentosa as the only manifestation of the disease. The diagnosis of mastocytosis in the father included bone marrow histopathological and cytological examinations and flow cytometry, and histopathological examination of the skin. In the children, tryptase measurement and skin histopathological examination were performed.
  
  
  METHODS
  Blood, urine, and buccal swab specimens were collected from the family members. HEK293T cells were transiently transfected with plasmids expressing KIT-WT and KIT-N882I. In addition, Ba/F3 cell lines expressing KIT-N822I, KIT-D816V, and KIT-V559D mutants were treated with imatinib and dasatinib. The effect of treatment on proliferation, survival, and signaling was determined.
  
  
  RESULTS
  Germ-line KIT-N822I missense mutation was detected in the affected members of the family. Western blot analysis using HEK293T and Ba/F3 cells expressing KIT-N822I isoform showed that KIT-N822I constitutively activated KIT tyrosine phosphorylation. In vitro assays on KIT-N822I-expressing Ba/F3 cells confirmed that the N822I mutant is resistant to imatinib mesylate. In contrast, a high efficacy of dasatinib toward the KIT-N822I-expressing Ba/F3 cells was observed.
  
  
  CONCLUSIONS
  We provided evidence that KIT p.N822I mutation has transforming potential and can cause a constitutive activation of KIT. In addition, we demonstrated that KIT-N822I is resistant to imatinib and sensitive to dasatinib. Finally, our findings support the hypothesis that not only KIT mutations but other additional genetic abnormalities are contributing to more advanced forms of the disease.
authors.affiliation: Department of Biology and Genetics, Medical University of Gdansk, Gdansk, Poland. bwasag@gumed.edu.pl
authors.forename: Bartosz
authors.initials: B
authors.lastname: Wasag
authors.forename: Marek
authors.initials: M
authors.lastname: Niedoszytko
authors.forename: Anna
authors.initials: A
authors.lastname: Piskorz
authors.forename: Magdalena
authors.initials: M
authors.lastname: Lange
authors.forename: Joanna
authors.initials: J
authors.lastname: Renke
authors.forename: Ewa
authors.initials: E
authors.lastname: Jassem
authors.forename: Wojciech
authors.initials: W
authors.lastname: Biernat
authors.forename: Maria
authors.initials: M
authors.lastname: Debiec-Rychter
authors.forename: Janusz
authors.initials: J
authors.lastname: Limon
mesh_terms: D000328:Adult; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D005192:Family Health; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D034701:Mastocytosis, Cutaneous / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D020125:Mutation, Missense; D010766:Phosphorylation; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism; D012867:Skin / Q000378:metabolism* / Q000473:pathology; D014162:Transfection
chemical_list: D019009:Proto-Oncogene Proteins c-kit