Alterations in the expression of EMT-related proteins claudin-1, -4 and -7, E-cadherin, TWIST1 and ZEB1 in oral lichen planus

BACKGROUND: Oral lichen planus (OLP) is a chronic T-cell-mediated inflammatory disease, which is associated with increased risk of developing oral squamous cell carcinoma. Epithelial-to-mesenchymal transition is a physiological phenomenon occurring during growth and organogenesis, but it has also an important role in tumorigenesis. In the present work, we studied the expression of known epithelial-to-mesenchymal transition markers in oral lichen planus. METHODS: In total, 54 oral lichen planus and 22 control samples were analyzed for epithelial-to-mesenchymal transition markers. Samples were immunohistochemically stained for claudin-1, claudin-4 and claudin-7, cadherin-1 (E-cadherin), Twist-related protein 1 (TWIST1) and zinc finger E-box-binding homeobox 1 (ZEB1). RESULTS: The expression of claudin-1, claudin-4 and E-cadherin was significantly weaker in oral lichen planus epithelium compared to controls (P < 0.001). The quantity of claudin-7-expressing cells (P < 0.001) and claudin-7 staining intensity (P < 0.05) in the stroma was greater in lichen planus than in control samples. TWIST1 and ZEB1 stainings were negative in the epithelium in both lichen planus and controls. The number of TWIST1-expressing cells in the stroma was higher in lichen planus than in controls (P < 0.001). There was a statistically significant difference in ZEB1 staining intensity in the stroma between lichen planus and control samples (P < 0.05). CONCLUSIONS: The data indicate that the expression of claudin-1, claudin-4 and E-cadherin is decreased in oral lichen planus. This may lead to disturbance in epithelial tight junctions, cell-cell connections and epithelial permeability, contributing to oral lichen planus pathogenesis. Based on the present study, the role of TWIST1 and ZEB1 in oral lichen planus remains unclear.