title: Relocalization of KIT D816V to cell surface after dasatinib treatment: potential clinical implications.
abstract: BACKGROUND
  Systemic mastocytosis (SM) is a heterogeneous disease that displays variable aggressivity. Adults with SM frequently have a D816V mutation in the tyrosine kinase (TK) receptor gene KIT. We previously reported that, in a Chinese hamster ovarian cell model expressing exogenous KIT variants, constitutive activating KIT mutations induced intracellular mislocalization of KIT reversed by inhibition of KIT TK activity. Hence, we hypothesized that inhibition of KIT kinase activity by the TK inhibitor dasatinib could be useful to increase KIT detection sensitivity in samples from patients with SM.
  
  
  METHODS
  We tested this hypothesis on a BaF/3 cell line modified to express either KIT wild-type (WT) or KIT D816V, on the human mastocytoma cell line HMC1.2, and among 28 patients with proven SM who did (n = 24) or did not (n = 4) carry the D816V KIT mutation and displayed various SM subtypes by using a simple flow cytometry assay to quantify KIT relocalization upon dasatinib treatment.
  
  
  RESULTS
  We confirm KIT cell surface increase upon dasatinib treatment on BaF/3 KIT D816V and HMC1.2 cell lines but not on BaF/3 KIT WT cell line. The analysis of bone marrow and peripheral blood samples of patients with SM showed KIT surface level increase for patients with the KIT D816V mutation but not for patients who had no KIT mutation. Interestingly, the extent of KIT level relocalization correlates with SM severity, with a higher relocalization for patients with aggressive forms compared with indolent forms.
  
  
  CONCLUSIONS
  Overall, results of this study suggests that treating the peripheral blood sample with dasatinib of a patient with SM before analysis by flow cytometry could contribute to narrowing the SM diagnosis.
authors.affiliation: CNRS UMR 8113, Laboratoire de Biologie et Pharmacologie Appliquée, École Normale Supérieure de Cachan, Cachan, France. houcine.bougherara@inserm.fr
authors.forename: Houcine
authors.initials: H
authors.lastname: Bougherara
authors.forename: Sophie
authors.initials: S
authors.lastname: Georgin-Lavialle
authors.forename: Gandhi
authors.initials: G
authors.lastname: Damaj
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Launay
authors.forename: Ludovic
authors.initials: L
authors.lastname: Lhermitte
authors.forename: Christian
authors.initials: C
authors.lastname: Auclair
authors.forename: Michel
authors.initials: M
authors.lastname: Arock
authors.forename: Patrice
authors.initials: P
authors.lastname: Dubreuil
authors.forename: Olivier
authors.initials: O
authors.lastname: Hermine
authors.forename: Marie-Alix
authors.initials: MA
authors.lastname: Poul
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D000069439:Dasatinib; D005260:Female; D006801:Humans; D008297:Male; D034721:Mastocytosis, Systemic / Q000097:blood / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use*; D019009:Proto-Oncogene Proteins c-kit / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011743:Pyrimidines / Q000627:therapeutic use*; D013844:Thiazoles / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D013844:Thiazoles; D019009:Proto-Oncogene Proteins c-kit; D000069439:Dasatinib