BRAF gene is somatically mutated but does not make a major contribution to malignant melanoma susceptibility: the Italian Melanoma Intergroup Study.
OBJECTIVE
Ocogenic activation of the BRAF gene has been demonstrated to be involved in the pathogenesis of malignant melanoma (MM). In this study, we investigated the contribution of BRAF to melanoma susceptibility, also making a comparison with frequency of CDKN2A germline mutations in MM patients from different areas in Italy.


METHODS
sing a combination of denaturing high-performance liquid chromatography analysis and automated sequencing on genomic DNA from peripheral blood or tumor tissue samples, 569 MM patients (211 from northern Italy and 358 from southern Italy) were screened for BRAF mutations.


RESULTS
Three BRAF germline sequence variants (M116R, V599E, and G608H) were identified in four (0.7%) of 569 MM patients. The most common BRAF mutation, V599E, was detected in one germline DNA sample only; M116R and G608H were newly described mutations. A high frequency (59%) of BRAF mutations was instead observed in tumor samples from patients also undergoing germline DNA analysis; at the somatic level, substitution of valine 599 was found to account for the majority (88%) of BRAF mutations. We then estimated the germline mutation rates in BRAF and CDKN2A among 358 consecutively collected patient samples originating in southern Italy; a low (2.5%) or very low (0.29%) prevalence of CDKN2A and BRAF mutations, respectively, was detected.


CONCLUSIONS
utation analysis of either blood DNA from a large collection of MM patients or matched MM tissues from a subset of such patients revealed that BRAF is somatically mutated and does not play a major role in melanoma susceptibility. The present study further suggests that patient origin may account for different mutation rates in candidate genes.
Casula
Milena
M
Istituto di Chimica Biomolecolare-Sezione di Sassari, CNR, Località Tramariglio-Alghero, 07040 Santa Maria La Palma (Sassari), Italy.
Colombino
Maria
M
Satta
Maria P
MP
Cossu
Antonio
A
Ascierto
Paolo A
PA
Bianchi-Scarrà
Giovanna
G
Castiglia
Daniele
D
Budroni
Mario
M
Rozzo
Carla
C
Manca
Antonella
A
Lissia
Amelia
A
Carboni
Annangela
A
Petretto
Elisabetta
E
Satriano
Sabrina M R
SM
Botti
Gerardo
G
Mantelli
Michela
M
Ghiorzo
Paola
P
Stratton
Michael R
MR
Tanda
Francesco
F
Palmieri
Giuseppe
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D020022:Genetic Predisposition to Disease; D018095:Germ-Line Mutation; D006801:Humans; D007558:Italy; D008297:Male; D008545:Melanoma / Q000209:etiology / Q000235:genetics*; D008875:Middle Aged; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics*; D012307:Risk Factors; D012878:Skin Neoplasms / Q000209:etiology / Q000235:genetics*
D004273:DNA, Neoplasm; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf