Mucin gene expression in gallbladder epithelium

Background and Purpose. The interaction of mucus, calcium and lipid is important in gallstone formation. The epithelium in stone-containing gallbladders has more mucin than in gallbladders without stones. There is altered mucin gene expression in black pigment stone-bearing gallbladders. In this study, we evaluated mucin gene expression in gallbladders containing cholesterol stones or calcium bilirubinate stones, and gallbladders without stones. Methods. In situ hybridization with digoxigenin-tailed oligonucleotides was performed on sections of paraffin-embedded epithelial tissue from gallbladders with cholesterol stones (n = 14) or calcium bilirubinate stones (n = 12), and those without stones ( n = 10) to identify expression of MUC1, MUC2, MUC3, MUC4, MUC5B, and MUC6. Results: The findings showed mRNA expression of MUC3, MUC5B and MUC6 in most gallbladders in all three groups, but stronger and extensive expression of these mRNAs in gallbladders with stones. MUC2 and MUC4 labeling was absent in gallbladders without stones, but MUC2 labeling was found in 14% and MUC4 in 50% of gallbladders with cholesterol stones. MUC2 expression was found in 25% and MUC4 in 58% of gallbladders with bilirubinate stones. Increased expression of MUC1 was found in gallbladders with cholesterol stones (79%) and calcium bilirubinate stones (83%) compared to those without stones (30%). Conclusion. Altered mucin gene expression was found in gallbladders with cholesterol stones and calcium bilirubinate stones, as evidenced by the presence of MUC2 and MUC4 and the increased expression of MUC1, MUC3, MUC5B and MUC6.