The Effects of Alteration of Expression of Cell Adhesion Molecules on Various Morphogenesis amd Biological Behaviors in Salivary Gland Tumors

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1. Cell adhesion molecules including E-cadherin,α,β-catenin, CD44v6 and v9 were intensely expressed on cell membranes in normal salivary glands and salivary gland tumors without myoepithelial participation, whereas in pleomorphic adenoma (PA) their expression intensity was reduced even in solid proliferation areas. In Adenoid cystic carcinoma (ACC), E-cadherin and β-catenin were detected on cell membrane, but their distribution exhibited irregularity with tiny spot-like depositions. In a few cases of ACC, β-catenin was present in the nuclei, suggesting that it may play some role in the tumorigenesis of ACC. On the other hand, reduced expression of CD44 variants may be not related to metastatic potential in ACC2. In cases of ACC showing reduced expression of E-cadherin and nuclear expression of β-catenin, overexpression of epidermal growth factor receptor (EGFR) was detected, suggesting that EGF-EGFR pathway may promote various genes through Wint signal transduction3. Extracellular matrices of ACC contained matrix metalloproteinase (MMP) -2 and -9 which may play an important role of destruction of basement membrane, invasion and metastasis of tumor cells4. The immortalized cell lines of PA and acinic cell carcinoma (AC) were obtained by transfection with hTERT gene. The immortalized PA cells were positive for both secretory markers such as lactoferrin and lysozyme and myoepithelial markers such as S-100 protein and calponin. These cells also expressed PLAG1 gene. On the other hand, AC cells expressed only secretory markers. These cell lines may represent a novel in vitro cell model for studies the regulatory mechanism of cellular differentiation and morphogenesis of salivary gland tumors