The expression of MUC4 and MUC5AC is related to the biologic malignancy of intraductal papillary mucinous neoplasms of the pancreas

Objective: Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas show heterogeneous proliferations with latent malignancy. Mucins (MUC) are high-molecular-weight glycoproteins, with an aberrant expression profile in various malignancies. Recently, MUC4 and MUC5AC expressions have been demonstrated to correlate with the unfavorable and the favorable prognosis of pancreatic duct cell carcinoma, respectively. However, little is known about these mucin expressions in IPMNs. Methods: To clarify the role of MUC4 and MUC5AC expressions in IPMNs, the expression profiles of MUC4 and MUC5AC were investigated in 50 lesions from 17 specimens with 16 IPMNs by immunohistochemistry, using each of their specific antibodies. Results: The expression of MUC4 was found in the lesions ranging from adenoma to cancer lesions of IPMNs, whereas it was undetectable in normal and hyperplastic lesions. Frequent expression of MUC4 is found in the higher grade of IPMNs (borderline and cancer lesions; 16/18 lesions, 94%). The differences were independently significant (P < 0.001) when the cutoff point was set between adenoma and borderline IPMNs. Similarly, frequent expression of MUC5AC was detected in the lesions from adenoma to cancer of IPMNs (32/34, 94%), whereas no intense expression was detected in normal or hyperplastic lesions. The significant difference was found when the cutoff point was set between hyperplasia and adenoma of IPMNs (P < 0.001). Conclusions: These results indicated that the expressions of MUC4 and MUC5AC are potential markers to distinguish adenoma or above malignant lesions of IPMNs from lesser malignant ones, respectively.