Expression of MUC1 and its significance in hepatocellular and cholangiocarcinoma tissue.

Aim: To investigate the relation between MUC1 expression, distribution, and prognosis in hepatocellular and cholangiocarcinoma (HCC and CC) and cirrhotic liver tissues, and their significance in HCC and CC diagnosis.

Methods: Expression and distribution of MUC1 were examined by immunohistochemical assay with anti-MUC1 mAb in 59 samples of HCC and 37 samples of CC, 20 samples of cirrhotic liver tissues, and 10 samples of normal liver tissues, seeking possible associations between MUC1 positive expression, distribution in HCC and CC (primary liver cancer, PLC) cases and the studied clinical data.

Results: Immunohistochemical analysis of MUC1 expression showed that in the 96 PLC samples, 68 (70.8%) were strong positive, and 6 (6.2%) were weak positive. Only 4 in the 20 cirrhotic liver tissues were found to be weak positive, while no expression of MUC1 was detected in normal liver tissues. Apparently, the high expression rate of MUC1 in PLC tissues was statistically significant in comparison to that in cirrhotic and normal liver tissues. The expressed MUC1 protein, stained in dark brownish or brownish-yellow particles, chiefly localized on the cancer cell membranes or in cytoplasm. In the 68 strong positive samples, 40 were detected on cell membrane and the other 28 were in cytoplasm. In addition, follow-up studies of those PLC cases demonstrated that MUC1 expression on cell membrane or in cytoplasm was closely associated with PLC prognosis. The expression of MUC1 in PLC had little statistical significance in respect of the pathological types and sizes of the tumors, but a strong relationship regarding histological differentiation, metastasis of lymph nodes, portal canal emboli, and post-operational recurrence of the carcinomas. After 3 years of tumor excision, the metastasis rate in MUC1 positive expression group (67.6%) was much higher than that in MUC1 weak expression group (33.3%) and negative expression group (31.8%), and thus the survival rate in MUC1-positive expression group was significantly different from that in weak and negative expression groups.

Conclusion: Expression and localization of MUC1 proteins in primary liver carcinomas (PLCs) may act as prognostic markers, and MUC1 molecules might be helpful in differential diagnosis.