The expression of MUC mucin in cholangiocarcinoma.

Cholangiocarcinoma (CC) is a highly malignant epithelial cancer of the biliary tract, the cellular and molecular pathogenesis of which remains unclear. Malignant transformation of glandular epithelial cells is associated with the altered expression of mucin. We investigated the type of mucins expressed in CC. Twenty-six patients with histologically confirmed CC were included in this study. The expression of mucin was studied by immunohistochemistry using antibodies to MUC1, MUC1 core, MUC2, MUC3, MUC4, MUC5AC, and MUC6. There was extensive (>50%) expression of mucin, mainly MUC1 in 11/25 and MUC5AC in 12/26 cases. In the case of MUC3, 6/26 cases expressed mucin extensively, whilst only 1/26 had MUC2, MUC4, and MUC6 expression. Well-differentiated tumors significantly expressed MUC3 extensively compared to poor or moderately differentiated tumors (p=0.003). Fifteen of 25 cases had metastatic disease. MUC1 was extensively expressed in 9/15 cases with metastatic disease. In contrast, MUC1 expression was present in 2/10 cases where metastases were absent. Hilar lesions were less likely to express MUC1, but this was not statistically significant. Fifteen of 25 cases had metastatic disease. Extensive MUC3 expression was significantly associated with well-differentiated tumors, whilst there was an approaching significance between the extensive expression of MUC1 and metastasis in cholangiocarcinoma.