Immortalization and characterization of pleomorphic adenoma cells by transfection with the hTERT gene.

Pleomorphic adenomas (PAs) of salivary glands are characterized by the mixed appearance of epithelial and mesenchymal-like components such as myxoid and chondroid tissues. Although various studies have examined PAs, thus far it is not clear how PAs make these multiple components. Thus, clarification of the histodifferentiation of this unique salivary gland tumor using not only tissues in vivo but also PA cells cultured in vitro is necessary. However, no in vitro model of PA has been reported, because normal and benign tumor cells tend to grow slowly and senesce quickly in culture. Therefore, we immortalized cells using transfection of the hTERT gene without otherwise altering the nature of those cells. The immortalized PA cells expressed mRNA of the pleomorphic adenoma gene 1 and showed epithelial and neoplastic myoepithelial characteristics by immunohistochemical immunofluorescence analyses and ultrastructural study. Our findings suggest that these cells will be a useful model to study the cellular differentiation of PA.