Abstract

Mucin 1 (MUC1) is a complex glycoprotein expressed on the apical surface of normal glandular epithelial cells. It plays a role in a number of biologic processes, and its overexpression is associated with various malignancies. A growing body of literature suggests that MUC1 is a potential diagnostic and therapeutic marker. Increasing numbers of variants are being identified for the MUC1 gene, but their role in carcinogenesis is unclear. Alternative splicing and a specific region on a variable number of tandem repeats are characteristic features of MUC1. However, the underlying mechanisms, overall prevalence, and the function of various MUC1 isoforms are not well characterized. In the present study, mRNA expression of nine variants of the MUC1 gene (A-D, X-Z, REP, SEC) was evaluated in normal and tumor tissues obtained from 50 patients with esophageal squamous cell carcinoma (ESCC). Associations between expression of various isoforms of MUC1 and important clinicopathologic factors were studied. Specific MUC1 splice variants (i.e., MUC1/C, D, and Z) are correlated with tumor progression in ESCC, whereas MUC1/B-previously suggested as a "normal" variant in some other cancers-has protective effects and is associated with more favorable tumor behavior and better prognosis. Specific isoforms of ESCC are associated with prognosis. Further characterization of different isoforms of MUC1 and their biologic effects is needed to explore their diagnostic and prognostic potential in clinical practice.