Gene expression of differentiation-specific keratins in oral epithelial dysplasia and squamous cell carcinoma

The aim of the study was to investigate the differentiation-specific keratins (K4, K13, K1 and K10) in oral epithelial dysplasia and squamous cell carcinoma (SCC). Alterations in keratin gene expression were determined by in situ hybridization using 35S-labeled riboprobes and immunohistochemistry with monoclonal antibodies. In mild dysplasia, both sets of differentiation keratins were expressed in the same group of cells but in moderate lesions, expression of K4 and K13 was reduced in the presence of enhanced K1 and K10 synthesis. In severe dysplasia, neither mRNAs nor proteins were detected. In tumor islands of well and moderately differentiated SCCs, the K4/K13 complex was co-expressed with K1/K10, but in poorly differentiated carcinomas, differentiation keratins were absent. Consequently, mild oral epithelial dysplasia and well differentiated SCC retain an essentially normal pattern of keratin gene expression and hence epithelial differentiation while in severe dysplasia and poorly differentiated SCC keratin gene expression reflects the gross changes in epithelial differentiation and maturation.