Epidermal growth factor receptor (EGFR) is overexpressed in many human colorectal cancers and anti-EGFR agents are employed as immunotherapies. However, KRAS, EGFR, and BRAF gene mutations can influence the activity of the anti-EGFR agents. We evaluated EGFR expression at protein and mRNA levels in canine intestinal adenocarcinomas using immunohistochemistry (IHC) and RNA in situ hybridization (RNA-ISH). We also investigated the mutation status of EGFR, KRAS, and BRAF to aid the development of anti-EGFR agents for canine intestinal adenocarcinoma. EGFR expression was highest in adenocarcinoma, followed by intramucosal neoplasia (adenoma and in situ carcinoma), and nonneoplastic canine intestinal tissue, at both protein (P = .000) and mRNA (P = .005) levels. The EGFR, KRAS, and BRAF genes showed wild-type sequences at the mutation hot spots in all 13 specimens. Thus, EGFR might serve as a promising diagnostic marker in canine intestinal adenocarcinoma, and further studies would be needed to develop EGFR-targeted anticancer therapies.
Keywords: BRAF; EGFR; KRAS; canine intestinal adenocarcinoma; mutation.