Mutational status of BRAF, NRAS genes in tumor material of patients diagnosed with cutaneous melanoma

Abstract

Melanoma is a complex disease influenced by changes in multiple genes and metabolic pathways that continue to evolve throughout the disease. Research into the genetic and molecular characteristics of melanoma is important for the development of new treatment strategies. The purpose of our study was to evaluate the survival rate and mutational status of the BRAF and NRAS genes in tumor material from patients diagnosed with cutaneous melanoma. A total of 54 patients with a confirmed diagnosis of cutaneous melanoma were included in the study: 36% were men (n=15), and women were 64% (n=39). The average age at diagnosis was 56 years. DNA was isolated from sections of paraffin blocks (FFPE) using a commercial kit QIAamp DNA FFPE Tissue Kit (QIAGENE, Germany). Analysis of the V600E mutation of the BRAF gene was carried out by allele-specific real-time PCR.  Exons 2 and 3 in the NRAS gene were analyzed by classical PCR (C1000 Touch BioRad, USA) followed by direct Sanger sequencing (ABI Prism 3500, Applied Biosystems, USA). Statistical analysis of the data was carried out using the Statistica 7.0 program. BRAF mutations were detected in 42.6% (V600E mutation 37.1%, V600K 5.4%), and NRAS mutations in 14.8% (Q61K 7%). In the remaining cases (42.6%), no changes were detected in any of the genes analyzed. The mutation status was closely related to the anatomical location of the tumor, so in the group with mutations in the BRAF and NRAS genes (65.3% and 37.0%, respectively; p = 0.002) patients with cutaneous primary lesions of the head and neck were noted. Mitotic activity was more frequently detected in primary tumors from patients with NRAS mutations than in patients with BRAF mutations (p = 0.002).