Expression of Different Glycoforms of Membrane Mucin (MUC1) and Secretory Mucin (MUC2, MUC5AC and MUC6) in Pancreatic Neoplasms

Our previous studies of pancreatic tumors have demonstrated that invasive ductal carcinoma (IDC) usually showed expression of MUC1 (membrane bound type mucin) detected by monoclonal antibody DF3, whereas intraductal papillary-mucinous neoplasm (IPMN) showed no expression of MUC1. In the present study, we examined 50 IDCs, and 63 IPMNs which were morphologically classified into two histological subtypes, "dark cell type" (IPMN-D, 27 cases) and "clear cell type" (IPMN-C, 36 cases). Patients with either type of IPMN showed significantly better survival than those with IDC. To clarify the relationship of the expression patterns of mucins with their biological behavior, we examined the expression profiles of various glycoforms of membrane mucin (MUC1) and secretory mucin (MUC2, MUC5AC and MUC6) in the neoplasms using immunohistochemistry. IDCs showed high expression of all the glycoforms of MUC1 (66%-98%). In contrast, IPMNs-D showed no or low expression of all the glycoforms of MUC1 (0%-4%), while IPMNs-C showed low expression of poorly glycosylated MUC1 (3%-6%), but expression of sialylated MUC1 (41%) and fully glycosylated MUC1 (69%). Expression of MUC2 was negative (0%) in IDC, high (96%) in IPMN-D and low (3%) in IPMN-C. MUC5AC was highly expressed in all types. MUC6 expression was higher in IPMNs-C (92%) than in IDCs (56%) and IPMNs-D (37%). In conclusion, the present study demonstrated that IDCs showed high expression of all the glycoforms of MUC1, and also that two types of IPMNs showed different expression patterns of glycosylated MUC1 as well as MUC2 and MUC6. These different expression patterns of mucins may be related with the malignancy potential of pancreatic neoplasms.