Differential Expression of MUC16 in Human Oral Mucosal Epithelium and Cultivated Epithelial Sheet

Abstract

Purpose:: Cultivated oral epithelial cell sheet transplantations represent a newly developed surgical strategy for the treatment of severe ocular surface disorders. Membrane-associated mucin, MUC16, expressed in the human corneal and conjunctival epithelial cells, plays an important role in the maintenance of a healthy and wet epithelium on the ocular surface. In this study, we investigated the expression of membrane-associated mucins MUC16 in human oral mucosal epithelium and compared with that in cultivated epithelial sheets.

Methods:: Specimens (3x3mm) of oral mucosal tissue were harvested from three healthy volunteers. The oral mucosal epithelial cells obtained from the specimens and corneal epithelial cells from eye bank donors were cultured with mitomycin-C-treated 3T3 feeder cells on temperature-responsive culture surfaces for 2 weeks to generate stratified cell sheets. Real-time PCR was used to investigate the mRNA expression of MUC16 in oral mucosal epithelium and the cultivated oral mucosal and corneal epithelial sheets. Sections containing the oral mucosal cells were subjected to immunohistochemical examination using MUC16 antibody (OC125) to determine the distribution of MUC16 protein in the oral mucosal epithelium and sheets.

Results:: MUC16 transcripts were detected in the cultivated oral mucosal and corneal epithelial sheets, but not in oral mucosal epithelium. Real-time PCR demonstrated that the expression of MUC16 mRNA in the corneal epithelial sheet was five to ten times higher than that in the oral mucosal epithelial sheet. MUC16 protein was localized in the apical cell layers of the cultivated oral mucosal and corneal epithelial sheets, but the human oral mucosal epithelium did not express MUC16 proteins in any cell layers.

Conclusions:: The findings of our study demonstrate the expression of membrane-associated mucin MUC16 is different in human oral mucosal epithelia and cultivated epithelial sheets. The cultivated oral mucosal epithelial sheet expressed MUC16 mRNA and protein, which is the same expression pattern as seen in human corneal epithelia. MUC16 expressed in the oral mucosal epithelial sheet may thus contribute to ocular surface reconstruction after oral mucosal epithelial sheet transplantation for patients with severe ocular surface disorders.

Keywords: cornea: surface mucins • transplantation • cornea: epithelium