Cytokeratin expression in squamous cell carcinomas of the tongue and alveolar mucosa

Cytokeratins (CK), the intermediate filament markers for epithelial cells were analysed in 23 squamous cell carcinomas (SCC) of the tongue and 11 SCC of the alveolar mucosa (AM) by SDS-PAGE, immunoblotting and two dimensional gel electrophoresis. Normal human adult ventral tongue expresses CK nos 4, 5, 6, 13, 14, 16 (17) while the dorsal tongue expresses CK nos 1, 5, 6, 10, 14, 16 (17). CK 5 and CK 14 were not detected in a majority of samples and CK 18, a marker of simple epithelia, was aberrantly expressed in 18 samples. Normal human adult AM expresses CK nos 4, 5, 6, 13, 14, 16 (17). Among 11 SCC of AM, CK 4 and CK 5 were detected in only two samples each. CK 1 and CK 10 were aberrantly expressed in nine and one samples, respectively. The basic CKs such as CK 4, 5 and 14 were not expressed in SCC at both these sites while others like CK 1 and 18 were aberrantly expressed. Thus, non-expression of basic keratin, CK 5, of the oral lining epithelia and aberrant expression of simple epithelial keratins seem to be the major events in malignant transformation in the oral epithelia.