Immunohistochemical changes in the epidermal growth factor receptor during carcinogenesis induced by 4-nitroquinoline 1-oxide in the rat tongue

Abstract

In order to understand the process of carcinogenesis in rat tongue carcinomas induced by 4-nitroquinoline 1-oxide (4NQO), I compared keratin expression with localization of the epidermal growth factor (EGFR) and its ligands. The tumor growth site was detected with anti-PCNA antibody. EGFR was expressed in the prickle cell layer of normal, hyperplastic, and dysplastic epithelium. This pattern was also observed in malignant epithelium. Highly differentiated areas in the central region of the tumor nest were intensively stained. EGF/TGFα and keratin expression was observed together with that of EGFR. I concluded that EGFR carried out an autocrine reaction with EGF/TGFα, that it was most likely involved in cellular keratin production, and that it closely correlated with squamous cell differentiation rather than tumor growth.