Down-regulation of desmosomal molecules in oral and pharyngeal squamous cell carcinomas as a marker for tumour growth and distant metastasis.

Down-regulation of adhesion molecules has been observed in a number of squamous cell carcinomas (SCC) and is considered to be associated with tumour invasiveness and lymph node metastasis. The present prospective investigation aimed at analyzing the expression patterns of desmosomal markers in oral and pharyngeal SCC and correlations that may exist between these patterns and tumour behaviour. Two constitutive desmosomal molecules, desmoplakin (Dp) and plakoglobin (Pg), were examined in 26 samples of primary carcinoma of the head and neck. The correlation between Dp and Pg expression was only moderate, reflecting functional differences between the two proteins. Whereas decreased Dp and Pg expression was closely associated with distant metastasis formation, reduced Pg expression was correlated to the development of large tumours. There were also variable relationships between the expression of these markers and lymph node invasion, histological differentiation, or survival of the patients. Biochemical analysis of cytoskeletal fractions confirmed the decrease in desmosomal proteins, particularly in tumours which later developed metastases. Down-regulation of Dp and Pg in oral and pharyngeal SCC may represent a reliable marker for extensive tumour growth and the risk of distant metastasis formation, Dp and Pg apparently having metastasis- and tumour-suppressor properties, respectively.