Assessment of BRAF V600E (VE1) protein expression and BRAF gene mutation status in codon 600 in benign and malignant salivary gland neoplasms.

Abstract

The role of BRAF mutations in cancerogenesis has been demonstrated in several solid tumor types. However, in salivary gland tumors, this genetic alteration is very uncommon, and its role still remains unclear. Thus, the aim of this study was to analyze BRAF V600E (VE1) protein expression with BRAF mutation status in codon 600, in malignant and benign salivary gland tumors. Studies were performed on archived formalin-fixed paraffin-embedded tissue sections derived from 95 patients who underwent surgery for tumors of the salivary gland. Immunohistochemical staining (IHC) on tissue microarray slides was performed for evaluation of BRAF V600E (VE1) protein expression, and the automatic molecular diagnostics platform was used for the evaluation of mutations in codon 600 of BRAF gene. IHC cytoplasmic expression of BRAF V600E (VE1) protein was found in two of 95 cases: one case of adenocarcinoma NOS (one of three; 33%) and one case of carcinoma ex pleomorphic adenoma (one of five; 20%). Although, in IHC studies, nuclear BRAF V600E (VE1) protein expression was found in 14 (15%) of the analyzed cases: nine of 28 (32%) cases of pleomorphic adenoma, three of five (60%) cases of ductal carcinoma, one of nine (11%) case of mucoepidermoid carcinoma, and in one of five (20%) case of carcinoma ex pleomorphic adenoma. All cases were negative for polymerase chain reaction PCR-based analyses of BRAF mutations in codon 600. In studied salivary gland cancers, no PCR-based prove mutations of BRAF V600 were detected. Further molecular analyses are necessary to rapid molecular arrays for the identification of specific mutations, optimal for individualized targeted therapies.