The expression of several types of mucin is related to the biological behavior of pancreatic neoplasms.

BACKGROUND/PURPOSE: Mucins are high molecular weight glycoproteins that have oligosaccharides attached to the apomucin protein backbone by O-glycosidic linkages. Here, we report the expression of MUC1 mucin (membrane-bound mucin), MUC2 mucin (intestinal-type secretory mucin), and MUC5AC mucin (gastric-type secretory mucin) in invasive ductal carcinomas (IDCs; n = 46) and intraductal papillary-mucinous neoplasms (IPMNs; n = 33) of the pancreas, and the relationship of this expression with malignant potential.

METHODS

To clarify the precise expression pattern of mucins in IPMNs, we classified IPMNs into three histologic subtypes; IPMN-dark cell type ( n = 19), IPMN-clear cell type ( n = 10), and IPMN-compact cell type ( n = 4).

RESULTS

IDC, with a poor outcome, showed a pattern of MUC1(+), MUC2(-), and MUC5AC(+ or -). In contrast, IPMN-dark cell type tumors, with a fairly favorable outcome, showed a pattern of MUC1(-), MUC2(+), and MUC5AC (+), and IPMN-clear cell type tumors, with a favorable outcome, showed a pattern of MUC1(-), MUC2(-), and MUC5AC(+). On the other hand, IPMN-compact cell type tumors showed a pattern of MUC1(+), MUC2 (-), and MUC5AC(+). In IPMN-dark cell type tumors with carcinomatous change showing invasive growth, the invasive areas acquired a characteristic of MUC1 expression that was usually seen in IDC, although their main noninvasive lesions showed no MUC1 expression. The IPMN-compact cell type tumors usually showed high cellular atypia and frequent MUC1 expression, even in the noninvasive areas.

CONCLUSIONS

Our study of the mucin expression pattern in IDC and IPMN shows that this pattern may be related to the biological behavior of pancreatic tumors and their malignant potential.