BRAF-V600E Protein Expression in Canine Malignant Cutaneous Melanoma, in Accordance with the Introduction of Biomarkers in Comparative Oncology Studies

Background: Melanoma is the cause of death for 1.3% of all cancer patients in hu-mans. The key role of the BRAF protein in the progression of human melanoma has been confirmed, and its prognostic significance has been revealed. Because canine cancer resembles human cancer in biological behavior and molecular abnormalities, BRAF protein may be expressed in canine melanoma, the same as human melano-ma. Despite the investigation of the BRAF mutation in canine melanoma, the status of BRAF at the protein level in canine skin melanoma has not yet been examined. Methods: Thirty-two formalin-fixed, paraffin-embedded tissue samples of canine malignant cutaneous melanoma were randomly selected. After cutting into 3-μm-thick sections, the samples were evaluated for BRAF protein expression by immuno-histochemistry and using the anti-BRAF V600E (VE1) mouse monoclonal antibody Results: The BRAF status was assessed using the Allred scoring system. Among the 32 samples examined, 21 samples were negative, and 11 cases showed high BRAF protein expression. Conclusion: The detection of positive BRAF expression in 34.3% of canine cuta-neous melanoma samples could be a step forward to improving treatment options, using dogs as an animal model in human melanoma clinical trials, and possibly iden-tifying a new prognostic biomarker in canine melanoma.