MUC4 (sialomucin complex) expression in salivary gland tumors and squamouscell carcinoma of the upper aerodigestive tract

OBJECTIVES: This study investigates MUC4 expression in normal squamous epit helia and squamous cell carcinoma (SCC) of the upper aerodigestive tract (U ADT), and in salivary gland neoplasms. STUDY DESIGN: MUC4 antigens in tumor and adjacent normal tissue are localiz ed by immunocytochemical studies. Fresh frozen tissues from surgical resect ion specimens are further analyzed by Western blot. RESULTS: MUC4 is identified by immunocytochemical staining throughout the n ormal UADT mucosa, in 34 of 40 primary UADT SCC, and in 11 of 12 metastatic cervical lymph nodes. A trend toward decreased MUC4 staining in moderately and poorly differentiated tumors is noted. Immunoblots show MUC4 in 4 of 5 SCC analyzed. Immunocytochemical staining of MUC4 in 13 major and minor sa livary gland neoplasms reveal variable staining of normal and neoplastic ti ssue. MUC4 is demonstrated in immunoblots of normal parotid tissue and in t he single parotid malignancy analyzed, but is not demonstrated in one minor salivary gland malignancy. These findings characterize normal UADT mucosal and salivary MUC4 expression, and MUC4 expression in SCC of the UADT and i n salivary gland tumors. SIGNIFICANCE Correlation of MUC4 expression with clinical outcomes may esta blish MUC4 as a potential molecular prognostic marker for these tumors.