Immunohistochemical study of MUC1 mucin in premalignant oral lesions and oral squamous cell carcinoma: association with disease progression, mode of invasion, and lymph node metastasis.

Abstract

MUC1 mucin is a transmembrane, mucin-like glycoprotein encoded by the MUC1 gene. Although MUC1 expression has been identified in a variety of neoplastic tissues, to the authors' knowledge, few studies have examined MUC1 expression in premalignant and malignant oral lesions. A total of 36 specimens of oral epithelial dysplasia, 12 carcinoma in situ (CIS) specimens and 77 specimens of oral squamous cell carcinoma (OSCC), were examined by both light and electron microscopy using immunohistochemical staining of MUC1 mucin. Relations between staining patterns and clinicopathologic findings also were examined. Distinct membrane MUC1 mucin staining patterns were identified in epithelial dysplasia (33.0%), CIS (50.0%), and OSCC (59.7%) cases. A predominantly cytoplasmic staining pattern was detected in epithelial dysplasia (5.6%), CIS (41.7%), and OSCC (32.5%) cases. Significant positive correlations were found between MUC1 mucin membranous immunoreactivity and disease progression from epithelial dysplasia to OSCC (P < 0.01), mode of tumor invasion (P < 0.02), and lymph node metastasis (P < 0.01). Furthermore, the malignant transformation of oral epithelium, tumor invasion, and tumor metastasis were associated with higher MUC1 mucin expression in the cytoplasm (P < 0.01). In addition to the usual cell surface expression, cytoplasmic expression of MUC1 mucin was confirmed by colloidal gold labeling with transmission electron microscopy. The results of the current study suggest that determination of MUC1 mucin expression may be a parameter in the diagnosis of premalignant and malignant lesions arising in the oral cavity and that this expression may affect the malignant behavior of OSCC. MUC1 mucin expression may be a useful diagnostic marker for prediction of the invasive/metastatic potential of OSCC.