Polyclonality of BRAF mutations in acquired melanocytic nevi.
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.
Lin
Jingrong
J
Department of Dermatology, Shinshu University School of Medicine, Matsumoto, Japan.
Takata
Minoru
M
Murata
Hiroshi
H
Goto
Yasufumi
Y
Kido
Kenji
K
Ferrone
Soldano
S
Saida
Toshiaki
T
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
D018698:Glutamic Acid; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D014633:Valine