Expression of Mutated BRAFV595E Kinase in Canine Carcinomas - An Immunohistochemical Study

Abstract

Molecular profiling of cancer is used to examine for specific mutations or proteins and is becoming increasingly important in oncology. An example of such a mutation is the altered BRAF gene and the resulting changed BRAF protein, which is already known to play a role in urinary bladder and prostatic carcinomas in dogs. We assumed that the mutant BRAFV595E protein should be considered in other canine carcinomas and tested 227 samples of 11 different carcinoma origins (anal sac (n = 23), intestine (n = 21), liver (n = 21), lungs (n = 19), mammary gland (n = 20), nasal cavity (n = 21), oral epithelium (n = 18), ovary (n = 20), prostate (n = 21), thyroid gland (n = 21), urinary bladder (n = 22)). We used immunohistochemistry with two different primary antibodies, each binding to the altered BRAF protein, and confirmed our results with droplet digital PCR (ddPCR). Among all the tested canine carcinomas, we found BRAF-mutated tumours in the prostate (16/21), the urinary bladder (17/22), and the oral cavity epithelium (4/18), while other carcinomas tested negative. Our findings showed that both antibodies are dependable tools for detecting the BRAFV595E mutation in canine carcinomas. Detecting BRAF mutations is important for applying future therapeutic approaches, including BRAF inhibitors.