The myoepithelial cell differentiation of mucoepidermoid carcinoma in a collagen gel-based coculture model

BACKGROUND: Mucoepidermoid carcinomas (MECs) are the most common malignant tumor of the salivary glands; however, the histogenesis of MECs has been still controversial. This study was undertaken to investigate the histogenesis of MECs by the examination of their collagen gel-based coculture tissue and transplanted tumors. METHODS: Two cell lines from a primary and a metastatic MECs were established and characterized by the mutational analysis of the p53 gene and in vivo tumorigenicity in athymic nude mice. Collagen gel-based organotypic cocultures were performed, and the ultrastructural and immuncohistochemical findings were examined. RESULTS: Two cell lines demonstrated p53 point mutation at the same codon. A metastatic cell line of MEC showed in vivo tumorigenicity. Transplanted tumors and the collagen gel-based culture tissues showed poorly differentiated squamous cell carcinomas devoid of mucous cell differentiation; however, they disclosed the differentiation of myoepithelial cells. CONCLUSIONS: MECs appear to be centered on the squamous cell differentiation, and the specific differentiation of myoepithelial or mucous cells seems to be modulated by the property of microenvironment.