title: BRAF mutations in hairy-cell leukemia.
abstract: BACKGROUND
  Hairy-cell leukemia (HCL) is a well-defined clinicopathological entity whose underlying genetic lesion is still obscure.
  
  
  METHODS
  We searched for HCL-associated mutations by performing massively parallel sequencing of the whole exome of leukemic and matched normal cells purified from the peripheral blood of an index patient with HCL. Findings were validated by Sanger sequencing in 47 additional patients with HCL.
  
  
  RESULTS
  Whole-exome sequencing identified five missense somatic clonal mutations that were confirmed on Sanger sequencing, including a heterozygous mutation in BRAF that results in the BRAF V600E variant protein. Since BRAF V600E is oncogenic in other tumors, further analyses were focused on this genetic lesion. The same BRAF mutation was noted in all the other 47 patients with HCL who were evaluated by means of Sanger sequencing. None of the 195 patients with other peripheral B-cell lymphomas or leukemias who were evaluated carried the BRAF V600E variant, including 38 patients with splenic marginal-zone lymphomas or unclassifiable splenic lymphomas or leukemias. In immunohistologic and Western blot studies, HCL cells expressed phosphorylated MEK and ERK (the downstream targets of the BRAF kinase), indicating a constitutive activation of the RAF-MEK-ERK mitogen-activated protein kinase pathway in HCL. In vitro incubation of BRAF-mutated primary leukemic hairy cells from 5 patients with PLX-4720, a specific inhibitor of active BRAF, led to a marked decrease in phosphorylated ERK and MEK. CONCLUSIONS; The BRAF V600E mutation was present in all patients with HCL who were evaluated. This finding may have implications for the pathogenesis, diagnosis, and targeted therapy of HCL. (Funded by Associazione Italiana per la Ricerca sul Cancro and others.).
authors.affiliation: Institute of Hematology, University of Perugia, Perugia, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Tiacci
authors.forename: Vladimir
authors.initials: V
authors.lastname: Trifonov
authors.forename: Gianluca
authors.initials: G
authors.lastname: Schiavoni
authors.forename: Antony
authors.initials: A
authors.lastname: Holmes
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kern
authors.forename: Maria Paola
authors.initials: MP
authors.lastname: Martelli
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pucciarini
authors.forename: Barbara
authors.initials: B
authors.lastname: Bigerna
authors.forename: Roberta
authors.initials: R
authors.lastname: Pacini
authors.forename: Victoria A
authors.initials: VA
authors.lastname: Wells
authors.forename: Paolo
authors.initials: P
authors.lastname: Sportoletti
authors.forename: Valentina
authors.initials: V
authors.lastname: Pettirossi
authors.forename: Roberta
authors.initials: R
authors.lastname: Mannucci
authors.forename: Oliver
authors.initials: O
authors.lastname: Elliott
authors.forename: Arcangelo
authors.initials: A
authors.lastname: Liso
authors.forename: Achille
authors.initials: A
authors.lastname: Ambrosetti
authors.forename: Alessandro
authors.initials: A
authors.lastname: Pulsoni
authors.forename: Francesco
authors.initials: F
authors.lastname: Forconi
authors.forename: Livio
authors.initials: L
authors.lastname: Trentin
authors.forename: Gianpietro
authors.initials: G
authors.lastname: Semenzato
authors.forename: Giorgio
authors.initials: G
authors.lastname: Inghirami
authors.forename: Monia
authors.initials: M
authors.lastname: Capponi
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Raimondo
authors.forename: Caterina
authors.initials: C
authors.lastname: Patti
authors.forename: Luca
authors.initials: L
authors.lastname: Arcaini
authors.forename: Pellegrino
authors.initials: P
authors.lastname: Musto
authors.forename: Stefano
authors.initials: S
authors.lastname: Pileri
authors.forename: Claudia
authors.initials: C
authors.lastname: Haferlach
authors.forename: Susanne
authors.initials: S
authors.lastname: Schnittger
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pizzolo
authors.forename: Robin
authors.initials: R
authors.lastname: Foà
authors.forename: Laurent
authors.initials: L
authors.lastname: Farinelli
authors.forename: Torsten
authors.initials: T
authors.lastname: Haferlach
authors.forename: Laura
authors.initials: L
authors.lastname: Pasqualucci
authors.forename: Raul
authors.initials: R
authors.lastname: Rabadan
authors.forename: Brunangelo
authors.initials: B
authors.lastname: Falini
mesh_terms: D000328:Adult; D000368:Aged; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006801:Humans; D007943:Leukemia, Hairy Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D016393:Lymphoma, B-Cell / Q000235:genetics / Q000473:pathology; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases