Immunohistochemical profiling of mucins in sinonasal adenocarcinomas

In this study we investigated the expression of mucins (MUC1, MUC2, MUC4, MUC5AC and MUC6) in a series of 66 sinonasal adenocarcinomas, in order to establish their distribution and the possible correlation with clinicopathological and prognostic parameters. The series included 51 intestinal type adenocarcinomas, 4 non-intestinal type adenocarcinomas, and 11 salivary gland type carcinomas. The immunohistochemical analysis was conducted on a tissue microarray obtained from formalin fixed-paraffin embedded tumor tissue samples. Thirty-nine adenocarcinomas (59.1%) resulted positive for MUC1, 21 (41.2%) for MUC2, 47 (71.2%) for MUC4, and 16 (24.2%) for MUC5AC, while MUC6 was negative in all cases tested. MUC1 was significantly more expressed in ITACs than in non-ITACs (70% vs 20%, p = 0.0007) while MUC2 was expressed only in ITACs (p = 0.0015) with a clear prevalence in the mucinous subtype (p < 0.0001). Conversely, MUC4 and MUC5AC were similarly expressed in the sinonasal adenocarcinoma subtypes tested. High expression of MUC 1 was related to a significantly shorter overall survival, both in the whole series (p = 0.04), while adenocarcinomas positive for MUC 2 tended to have a worse overall survival (p = 0.07). In addition, MUC2 expression was higher in ITACs with distant metastasis, being expressed in 4 out of 5 cases (p = 0.015). We conclude that sinonasal adenocarcinomas have a characteristic expression of different mucin types, with significant clinicopathologic correlations. In view of the extensive involvement of mucins in different aspects of tumor growth and their emerging role as possible therapeutic targets, our study suggests that these factors could be considered clinically relevant biomarkers and attractive targets for new treatments in sinonasal adenocarcinomas.