Hotspot mutations of BRAF gene are not associated with pediatric solid neoplasms

BRAF (v-raf murine sarcoma viral oncogene homolog B1) activating mutations in a high proportion of melanomas and in a small fraction of other cancers have been recently reported. All the presented mutations of BRAF are located in exons 11 and 15, and the hotspot mutation at codon 599 accounts for 87% of BRAF mutations. Because the mutational status is unclear in pediatric solid neoplasms, we screened BRAF mutations comprehensively in our tumor series presented in childhood. Two pairs of primers were designed to amplify exons 11 and exon 15, respectively, and 181 tumor samples (65 neuroblastomas, 23 Wilms tumors, 19 hepatoblastomas, 16 teratomas, 17 rhabdomyosarcomas, 13 ganglioneuromas, etc.) were investigated by PCR-SSCP method. On agarose gel electrophoresis, amplified PCR fragments showed no size-altered changes in exons 11 and 15, and SSCP analysis revealed uniform band patterns in both exons. Subsequent direct sequencing of selected 10 samples confirmed only normal sequences without any nucleotide substitutions. The current study represents the first genetic analysis of the BRAF gene in pediatric solid tumors. Our data suggest that mutations of BRAF gene as a mechanism of tumorigenesis is unlikely to be associated with most childhood neoplasms.