Variations of BRAF mutant allele percentage in melanomas

Abstract : BACKGROUND: BRAF mutations are present in 40% of human skin melanomas. Mutated tumors with an increased percentage of BRAF mutant alleles (BRAF-M%) may have a better response to RAF/MEK inhibitors. We evaluated the BRAF-M% in melanomas, and the genetic causes of its variation. METHODS: BRAF-M% was quantified by pyrosequencing, real-time PCR (rtPCR) and/or picoliter-droplet PCR (dPCR). BRAF mutant expression was detected by immunohistochemistry. Chromosomal alterations were analyzed with fluorescence in situ hybridization (FISH), and single nucleotide polymorphism (SNP) arrays. RESULTS: BRAF-M% quantification obtained with pyrosequencing was highly correlated (R = 0.94) with rtPCR, and with dPCR. BRAF-M% quantified from DNA and RNA were also highly correlated (R = 0.98). Among 368 samples with >80% tumor cells, 38.6% had a BRAF (V600E) mutation. Only 66.2% cases were heterozygous (BRAF-M% 30 to 60%). Increased BRAF-M% (>60%) was observed in 19% of cases. FISH showed a polysomy of chromosome 7 in 13.6%, 35.3% and 54.5% of BRAF wild-type, heterozygous and non-heterozygous BRAF-mutated samples, respectively (P < 0.005). Amplification (5.6%) and loss (3.2%) of BRAF locus were rare. By contrast, chromosome 7 was disomic in 27/27 BRAF-mutated nevi. CONCLUSIONS: BRAF-M% is heterogeneous and frequently increased in BRAF-mutant melanomas. Aneuploidy of chromosome 7 is more frequent in BRAF mutant melanomas, specifically in those with high BRAF-M%.
Document type :
Journal articles
Complete list of metadatas

Cited literature [38 references]  Display  Hide  Download

https://www.hal.inserm.fr/inserm-02299570
Contributor : Valerie Taly <>
Submitted on : Friday, September 27, 2019 - 6:22:06 PM
Last modification on : Wednesday, October 2, 2019 - 1:16:01 AM

File

s12885-015-1515-3.pdf
Publisher files allowed on an open archive

Identifiers

Citation

Zofia Hélias-Rodzewicz, Elisa Funck-Brentano, Laure Baudoux, Chan Kwon Jung, Ute Zimmermann, et al.. Variations of BRAF mutant allele percentage in melanomas. BMC Cancer, BioMed Central, 2015, 15 (1), pp.497. ⟨10.1186/s12885-015-1515-3⟩. ⟨inserm-02299570⟩

Share

Metrics

Record views

39

Files downloads

71