Alterations of Rb, p16INK4A and cyclin D1 in the tumorigenesis of oral squamous cell carcinomas

Immunohistochemical analysis of Rb, p16INK4A and cyclin D1 expression was performed on 78 oral squamous cell carcinoma (SCC), 46 leukoplakia, and 20 normal mucosa. Rb and p16INK4A expression were observed in all normal mucosa and most of leukoplakia. Lack of Rb and p16INK4A was observed in 56.4 and 67.9% of SCC, respectively. The overexpression of cyclin D1 was not observed in normal mucosa and was observed in 35.9% of SCC. A strong reciprocal relationship between Rb and p16INK4A expression was observed in oral SCC, and all these SCC cases have at least one of the alterations in the Rb pathway.