EPITHELIAL-MESENCHYMAL TRANSDIFFERENTIATION AND EXTRACELLULAR-MATRIX GENE-EXPRESSION IN PLEOMORPHIC ADENOMAS OF THE PAROTID SALIVARY-GLAND

Mesenchymal and epithelial cell differentiation are assumed to be dich otomic primary events in embryonic development; in this study, pleomor phic adenomas of the parotid gland were analysed as a model which show s morphological features of both epithelial and mesenchymal tissue typ es. Using matrix; gene expression profiles as a supplementary criterio n for the identification of cellular phenotypes, areas with unequivoca l epithelial and mesenchymal differentiation could be demonstrated. Ma ny areas displayed a transitional phenotype with cells shelving both e pithelial and mesenchymal features. The data provide evidence that epi thial-mesenchymal transitions represent the basic principle of the tis use heterogeneity in pleomorphic adenomas, Thus, pleomorphic adenomas demonstrate the potential of adult (neoplastic) epithelial cells to tr ansdifferentiate into mesenchymal cells ill vivo. (C) 1998 John Wiley. & Sons, Ltd.