title: Polyclonality of BRAF mutations in acquired melanocytic nevi.
abstract: Melanocytic nevi are thought to be senescent clones of melanocytes that have acquired an oncogenic BRAF mutation. BRAF mutation is considered to be a crucial step in the initiation of melanocyte transformation. However, using immunomagnetic separation or laser-capture microdissection, we examined BRAF mutations in sets of approximately 50 single cells isolated from acquired melanocytic nevi from 13 patients and found a substantial number of nevus cells that contained wild-type BRAF mixed with nevus cells that contained BRAF(V600E). Furthermore, we simultaneously amplified BRAF exon 15 and a neighboring single nucleotide polymorphism (SNP), rs7801086, from nevus cell samples obtained from four patients who were heterozygous for this SNP. Subcloning and sequencing of the polymerase chain reaction products showed that both SNP alleles harbored the BRAF(V600E) mutation, indicating that the same BRAF(V600E) mutation originated from different cells. The polyclonality of BRAF mutations in acquired melanocytic nevi suggests that mutation of BRAF may not be an initial event in melanocyte transformation.
authors.affiliation: Department of Dermatology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Jingrong
authors.initials: J
authors.lastname: Lin
authors.forename: Minoru
authors.initials: M
authors.lastname: Takata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Murata
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Goto
authors.forename: Kenji
authors.initials: K
authors.lastname: Kido
authors.forename: Soldano
authors.initials: S
authors.lastname: Ferrone
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Saida
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D018698:Glutamic Acid; D006801:Humans; D007564:Japan; D008297:Male; D008544:Melanocytes / Q000378:metabolism*; D008875:Middle Aged; D009154:Mutation; D009508:Nevus, Pigmented / Q000235:genetics*; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014633:Valine
chemical_list: D018698:Glutamic Acid; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D014633:Valine