Parotid acinar cells transiently change to duct-like cells during epithelial-mesenchymal transition

Hyposecretion of saliva and consequent dry mouth lead to severe caries and periodontal disease. Therapeutic radiation for head and neck cancer and sialadenitis result in atrophy and fibrosis of salivary glands, but the mechanism is not clear. As a model for dysfunction of salivary glands, we examined the change of gene expression patterns in primary cultured parotid acinar cells. The expression levels of acinar markers such as amylase and aquaporin-5 rapidly decreased during culture. At the same time, ductal markers began to be expressed although their expression was transient. In the late phase of culture, markers of epithelial-mesenchymal transition began to be expressed and increased. Inhibitor for Src or p38 MAP kinase suppressed these changes. These results suggest that parotid acinar cells transiently change to duct-like cells during epithelial-mesenchymal transition and that these changes are induced by signal transduction via Src-p38 MAP kinase pathway. There is a possibility that parotid acinar cells retain a plasticity of differentiation.