Immunohistochemical study of MUC1 mucin in premalignant oral lesions and oral squamous cell carcinoma - Association with disease progression, mode ofinvasion, and lymph node metastasis

BACKGROUND. 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 examine d MUC1 expression in premalignant and malignant oral lesions. METHODS. 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 immunohist ochemical staining of MUC1 mucin. Relations between staining patterns and c linicopathologic findings also were examined. RESULTS. Distinct membrane MUC1 mucin staining patterns were identified in epithelial dysplasia (33.0%), CIS (50.0%), and OSCC (59.7%) cases. A predom inantly cytoplasmic staining pattern was detected in epithelial dysplasia ( 5.6%), CIS (41.7%), and OSCC (32.5%) cases. Significant positive correlatio ns were found between MUC1 mucin membranous immunoreactivity and disease pr ogression from epithelial dysplasia to OSCC (P < 0.01), mode of tumor invas ion (P < 0.02), and lymph node metastasis (P < 0.01). Furthermore, the mali gnant transformation of oral epithelium, tumor invasion, and tumor metastas is were associated with higher MUC1 mucin expression in the cytoplasm (P < 0.01). In addition to the usual cell surface expression, cytoplasmic expres sion of MUC1 mucin was confirmed by colloidal gold labeling with transmissi on electron microscopy. CONCLUSIONS. 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 m ay affect the malignant behavior of OSCC. MUC1 mucin expression may be a us eful diagnostic marker for prediction of the invasive/metastatic potential of OSCC. (C) 2000 American Cancer Society.