Transmembrane MUC1 assists oral microbial colonization in oral mucosa of potentially malignant disorders and oral squamous carcinoma

Transmembrane mucin 1 (tMUC1) provides oral mucosal barrier against pathogens. The invasion of oncopathogenic microbes can promote cancerous proliferation of cells via inflammatory responses, abnormal cellular signaling, angiogenesis, anti-adhesion, and tumorigenesis. Oral potentially malignant disorders (OPMDs), such as oral lichen planus (OLP) and oral leukoplakia (OLK), include lesions with often dysplastic features and a risk of malignant transformation to oral squamous cell carcinoma (OSCC). This study examined the expression of tMUC1 and oral microbial colonization in these conditions using scanning electron microscopy (SEM). Forty-one formalin-fixed, paraffin-embedded biopsies were distinguished into controls, OLP, OLK, and OSCC groups. They were immunohistochemically stained for tMUC1 and were evaluated on light microscopy and SEM. Immunohistochemical expression of tMUC1 was limited to superficial layers in controls. OSCC presented considerable staining in all epithelial layers, whereas OLP and OLK samples showed no to minimal staining in the intermediate and superficial layers of epithelium. SEM displayed increased oral microbial colonization on the superficial surface of OLP and OLK when compared to controls. The altered expression of tMUC1 in OLP, OLK, and OSCC may enhance oral microbial colonization. OPMDs' transformation to OSCC could be due to influence of inflammatory response to microbial colonization.