Sialylated MUC1 mucin expression in normal pancreas, benign pancreatic lesions, and pancreatic ductal adenocarcinoma.

BACKGROUND/AIMS: Pancreatic cancer has the poorest prognosis of all gastrointestinal cancers. Because sialylated mucin influences the biologic behavior of carcinoma cells, we investigated sialylated MUC1 mucin expression in patients with pancreatic ductal adenocarcinoma.

METHODOLOGY: The expression of sialylated MUC1 mucin was examined in 55 pancreatic ductal adenocarcinomas, 2 normal pancreas specimens, 3 chronic pancreatitis specimens, 1 ductal hyperplasia of the pancreas, 3 mucinous cystadenomas, and 2 liver metastases from pancreatic ductal adenocarcinoma. Expression was assessed by immunohistochemistry with a new monoclonal antibody (mAb) (MY.1E12).

RESULTS: Sialylated MUC1 mucin was expressed in the cancer cell membrane in all the ductal carcinomas. The reaction product was seen at the apical aspect of cells when these were in tubule formation. This pattern was also detected in mucinous cystadenomas. However, it was seen diffusely in the cell membrane in single cancer cells or small clusters of cells without tubule formation and in metastatic liver tumors. Namely, invading or metastatic cancer cells expressed this type of mucin throughout the entire cell membrane. The expression of sialylated MUC1 mucin was not observed in specimens from normal pancreas, chronic pancreatitis, or ductal hyperplasia of the pancreas. In normal pancreas and these lesions, expression of sialylated Mession of sialylated MUC1 was limited to acini and secreted mucin.

CONCLUSIONS: Sialylated MUC1 mucin, which is expressed throughout the cancer cell membrane, may be a factor in the metastatic potential of pancreatic ductal adenocarcinoma.