Immunihistochemical detection of galNAc-T6 to predict survival in patients with colon cancer.

Abstract

e14682 Background: Alterations in the O-glycosylation is one of the most common changes during colon carcinogenesis, which leads to the expression of short O-glycan antigens (Tn, sialyl-Tn, Tk, and core 6). These structures are associated with malignant behavior being actively investigated as targets for immunotherapy. The enzymes of GalNAc-T family regulate the initial step in mucins O-glycosylation and could be responsible for the altered glycosylation observed in cancer. The aim of this work was to evaluate the expression of GalNAc-T6 in colon cancer, and to determine its role as prognostic marker. Methods: We evaluated GalNAc-T6 expression in colon cell lines by immunocytochemistry, and in colon cancer tissue samples by immunohistochemistry using the monoclonal antibody T6.3 developed by us (Berois et al. J Histochem Cytochem. 2006). We analyzed 103 colon cancer samples and 10 normal colon tissues. Results: We found that GalNAc-T6 (usually expressed in normal placenta, trachea, pancreas and brain) is detected in colon cancer cell lines. GalNAc-T6 was also detected by immunohistochemistry in 50.5% of samples with cancer and no expression was found in normal colon tissue. The staining pattern was predominantly cytoplasmic. Multivariate analysis showed that GalNAc-T6 expression is an independent prognostic marker predicting improved survival in patients with positive tumors (p 0.014). Conclusions: GalNAc-T6 could be a new independent prognostic marker to predict better outcome in colon cancer patients.