Expression of MUC5AC in colorectal carcinoma and relationship with prognosis

Overexpression and alterations in the glycosylation of gastric mucins have been described in colorectal carcinoma. The purpose of our study was to confirm aberrant expression of MUC5AC in colorectal carcinoma, to investigate relationships between clinicopathological parameters and MUC5AC expression, and to determine if MUC5AC expression may be a prognostic factor for colorectal carcinoma. Immunohistochemical staining using an antibody against MUC5AC tandem repeat epitopes was performed on colorectal tumor specimens (n=41), their metastatic tumors in regional lymph nodes (n=21) and normal colonic mucosa (n=41). We also documented clinicopathological parameters such as the age and sex of the patient, location, size, Dukes stage, histological type and grade of the tumor, pre-sence and number of metastatic lymph nodes, lymphatic, venous and perineural invasion, presence of preoperative and postoperative metastatic tumors and tumor recurrence. MUC5AC was expressed in 34.1% of tumor samples, 24.4% of normal colonic mucosa samples and 19% of lymph node metastases. MUC5AC showed ectopic expression in colorectal carcinoma and was also expressed strongly in mucinous carcinoma (60%). The number of tumors that expressed MUC5AC was lower in patients older than 60 years, in rectum-localized tumors and in patients who had evidence of recurrence and/or metastasis in the postoperative period. The patients with MUC5AC-negative tumors had a lower incidence of being disease free and of overall survival. In conclusion, the patients with MUC5AC-negative tumors had poor clinicopathological parameters and showed worse survival than patients with MUC5AC-positive tumors. Absence of MUC5AC expression in tumors can be a prognostic factor for more aggressive colorectal carcinoma.