Presence of BRAF V600E Mutation in Nevus Cases

Objective: V-raf murine sarcoma viral oncogene homolog B1 (BRAF), belongs to the family of V-RAF-1 murine leukemia viral oncogene homolog I (RAF) gene located in the long arm of chromosome 7 (7q34). The BRAF gene encodes a protein that has function in mitogen activated protein kinase (MAPK) signaling pathway with serin/threonin kinase activity. It has been suggested that presence of diverse mutations in BRAF gene may activate MAPK signaling pathway and nuclear transcription factors and then may cause cellular proliferation. T1796A transversion has been defined in melanomas in 15(th) exon BRAF gene sequence. This transversion results in missense coding of glutamic acid rather than valin at aminoacid at position 600. The incidence of the V600E mutation in the melanoma samples has been suggested as approximately 90% in the literature. The aim of this study is to analyze incidence of BRAF V600E mutation in the Turkish nevus cases. Material and Methods: Thirty nevus cases, diagnosed in the department of Pathology Pamukkale University School of Medicine, were included in this study. After DNA isolation from the paraffin embedded tissue sections, presence of BRAF V600E mutation was investigated by the amplification of DNA segment including 1796 nucleotide region with polymerase chain reaction and direct DNA sequencing. In addition, putative effects of BRAF V600E gene mutation on MAPK signaling pathway activation was investigated by immunohistochemistry using Anti Active pAb ERK 1/2 antibody in these cases. Results: The presence of T1796A transversion that results in V600E mutation is determined in five of thirty cases (16.6%). Immunohistochemistry results, using Active pAb ERK 1/2 antibody, suggested that the presence of V600E mutation did not activate MAPK signaling pathway in these cases. Conclusion: Results of this study suggest that the incidence of BRAF V600E mutation in our nevus cases is not as high as the ones described in the literature. However, to have a more reliable result for Turkish patients, the number of patients included in this study should be increased