Expression of integrin α9 subunit and tenascin in oral leukoplakia, lichen planus, and squamous cell carcinoma

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Abstract
OBJECTIVES: Integrin α9 subunit is a member of β1 integrin family and binds tenascin (TN). It is expressed by stratified squamous epithelium and may be associated with cell differentiation and growth. We studied if the expression of α9 integrin and TN is altered in leukoplakia, lichen planus, and squamous cell carcinoma (SCC).METHODS: Frozen sections of tissue samples obtained from normal human keratinized (16 subjects) and non‐keratinized (three subjects) oral mucosa, oral leukopakias with dysplasia (19 subjects), reticular type lichen planus (nine subjects), or oral mucosal SCC (23 subjects) were stained immunohistochemically with antibodies against α9 integrin and TN.RESULTS: In contrast to its most prominent localization at the cell membranes of the basal epithelial cells in the normal mucosa, α9 integrin was localized in a more diffuse pattern with focal loss of expression at the epithelial cell membranes in leukoplakic dysplasia, lichen planus, and SCC. In some areas of SCC, α9 integrin localized throughout all cell layers of the tumor epithelium. In most areas, α9 integrin colocalized with TN but in heavily inflamed areas there was focal loss of TN and α9 integrin at the basement membrane zone.CONCLUSIONS: The findings show that α9 integrin expression is altered in leukoplakic dysplasia, lichen planus, and SCC.