Prognostic significance of mucins in colorectal cancer with different DNA mismatch-repair status

Background: Expression of mucin antigen MUC1 and down regulation of MUC2 are associated with adverse prognosis in colorectal cancer (CRC), but their prognostic significance with respect to differing DNA mismatch repair (MMR) status is poorly understood. Objective: To determine the prognostic significance of MUC1 and MUC2 in CRC with different MMR statuses. Methods: Using the tissue microarray (TMA) technique, a series of 1420 unselected, non-consecutive CRC resections was subdivided into three groups: (1) MMR-proficient; (2) MLH1-negative; and (3) presumed hereditary non-polyposis colon cancer (HNPCC). Immunohistochemical analysis of MUC1 and MUC2 expression (> 0%) and loss (0%) was performed, and the results were correlated with clinicopathological parameters. Results: In MMR-proficient CRC, MUC1 expression was more frequently found in tumours with higher tumour stage (p = 0.004) and higher tumour grade (p = 0.041) and loss of MUC2 was associated with higher tumour stage (p = 0.028), node stage (p = 0.001), presence of vascular invasion (p = 0.028) and worse survival (p = 0.034). In MLH1-negative CRC, MUC2 loss was associated with the presence of lymph node metastasis (p = 0.028) and worse survival (p = 0.015), but there was no association between MUC1 expression and clinicopathological features. In presumed HNPCC, MUC1 expression and MUC2 loss were not associated with clinicopathological parameters. Conclusions: Mucins have a prognostic significance in sporadic CRC, but not in hereditary CRC. Loss of MUC2 is an adverse prognostic factor in MMR-proficient and MLH1-negative CRC, whereas MUC1 expression is associated with tumour progression in MMR-proficient CRC only.