Determinación de la mutación BRAF V600E en melanomas de pacientes uruguayos

María Eugenia Mazzei; Jimena Hochmann; Gonzalo Manrique; Ana Luisa Mariño; Lucía Delgado; Miguel Martínez Asuaga

Authors

María Eugenia Mazzei Universidad de la República, Facultad de Medicina, Hospital de Clínicas, Cátedra de Dermatología. Profesora Adjunta
Jimena Hochmann Universidad de la República, Facultad de Medicina, Cátedra de Genética
Gonzalo Manrique Universidad de la República, Facultad de Medicina, Cátedra de Medicina Nuclear
Ana Luisa Mariño Universidad de la República, Facultad de Medicina, Hospital de Clínicas, Cátedra de Anatomía Patológica. Profesora Agregada
Lucía Delgado Universidad de la República, Facultad de Medicina, Hospital de Clínicas, Cátedra de Oncología Clínica. Profesora
Miguel Martínez Asuaga Universidad de la República, Facultad de Medicina, Hospital de Clínicas, Cátedra de Dermatología. Profesor

Keywords:

PROTO-ONCOGENE PROTEINS B-RAF, MUTATION, MELANOMA

Abstract

Introduction: identifying genetic changes that occur in melanoma genesis has enabled the development of therapies that are specifically geared against such changes, what resulted in an increase of patients' survival for the first time in the history of systemic treatment of melanoma, in patients with advanced disease. The best results have been obtained with vemurafenib, a therapy that targets the BRAF protein and is only effective in the presence of the V600E mutation. Thus, its frequency in a certain population measures its potential impact in health figures.
Objective: to evaluate the frequency of the V600E mutation in BRAF in melanomas of Uruguayan patients.
Method: 28 samples of microdissected melanoma were studied and V600E mutation was tested through ASO-PCR (allele specific oligonucleotide - polymerase chain reaction).
Results: we managed to amplify DNA in 27 out of the 28 samples and the mutation was identified in 21 of them (FR: 0.78).
Discussion: previous works demonstrated a lower presence of melanomas that are carriers of the V600E mutation of BRAF (40%-60% in the Caucasian population and 25% in the Asian population) than what our study revealed. Our results, in spite of the need to include a larger number of patients, could partially be due to differences in the technique used and maybe as a consequence of a different proportion of patients with melanomas associated to the intermittent sun exposure.

References

(1) Barrios E, Vassallo J, Alonso R, Garay M, Musetti C. III Atlas de incidencia del cáncer en Uruguay 2002-2006. Montevideo: Comisión Honoraria de Lucha contra el Cáncer, 2010.
(2) Ko JM, Fisher DE. A new era: melanoma genetics and therapeutics. J Pathol 2011; 223(2):241-50.
(3) Serrone L, Zeuli M, Sega FM, Cognetti F. Dacarbazine-based chemotherapy for metastatic melanoma: thirty-year experience overview. J Exp Clin Cancer Res 2000; 19(1):21-34.
(4) Chapman PB, Hauschild A, Robert C, Haanen JB, Ascierto P, Larkin J, et al. Improved survival with vemurafenib in melanoma with BRAF V600E mutation. N Engl J Med 2011; 364(26):2507-16.
(5) Poulikakos PI, Zhang C, Bollag G, Shokat KM, Rosen N. RAF inhibitors transactivate RAF dimers and ERK signalling in cells with wild-type BRAF. Nature 2010; 464(7287): 427-30.
(6) Rubinstein JC, Sznol M, Pavlick AC, Ariyan S, Cheng E, Bacchiocchi A, et al. Incidence of the V600K mutation among melanoma patients with BRAF mutations, and potential therapeutic response to the specific BRAF inhibitor PLX4032. J Transl Med 2010; 8:67-9.
(7) Davies H, Bignell GR, Cox C, Stephens P, Edkins S, Clegg S, et al. Mutations of the BRAF gene in human cancer. Nature 2002; 417(6892):949-54.
(8) Curtin JA, Fridlyand J, Kageshita T, Patel HN, Busam KJ, Kutzner H, et al. Distinct sets of genetic alterations in melanoma. N Engl J Med 2005; 353(20):2135-47.
(9) Avruch J, Khokhlatchev A, Kyriakis JM, Luo Z, Tzivion G, Vavvas D, et al. Ras activation of the Raf kinase: tyrosine kinase recruitment of the MAP kinase cascade. Recent Prog Horm Res 2001; 56:127-55.
(10) Si L, Kong Y, Xu X, Flaherty KT, Sheng X, Cui C, et al. Prevalence of BRAF V600E mutation in Chinese melanoma patients: large scale analysis of BRAF and NRAS mutations in a 432-case cohort. Eur J Cancer 2012; 48(1):94-100.
(11) Going JJ, Lamb RF. Practical histological microdissection for PCR analysis. J Pathol 1996; 179(1):121-4.
(12) Sapio MR, Posca D, Troncone G, Pettinato G, Palombini L, Rossi G, et al. Detection of BRAF mutation in thyroid papillary carcinomas by mutant allele-specific PCR amplification (MASA). Eur J Endocrinol 2006; 154(2):341-8.
(13) Ascierto PA, Kirkwood JM, Grob JJ, Simeone E, Grimaldi AM, Maio M, et al. The role of BRAF V600 mutation in melanoma. J Transl Med 2012; 10:85.
(14) Sans M, Salzano FM, Chakraborty R. Historical genetics in Uruguay: estimates of biological origins and their problems. Hum Biol 1997; 69(2):161-70.
(15) Cheng S, Koch WH, Wu L. Co-development of a companion diagnostic for targeted cancer therapy. N Biotechnol 2012; 29(6):682-8.