Abstract

Background: Local and metastatic recurrence are frequent events in colorectal cancer. Certain indicators such as glycoproteins and carbohydrate antigens in primary tumors may be useful for early detection of disease dissemination. The purpose of this study was to evaluate the expression of mucins and carbohydrates associated antigens in normal, benign and malignant colorectal tissue samples. Methods: Immunohistochemical analysis was performed on 114 colorectal carcinoma samples, 22 adenomas and 35 normal colorectal mucosa specimens. Different monoclonal antibodies (MAbs) were studied: anti-MUC2 mucin (PMH1), MUC1 (CT2 and HMFG2) and anti-alpha 1 glycoprotein (AGP). We also analyzed carbohydrate antigens such as Lewis x (KM380), sialyl Lewis x (KM93), Lewis y (C14) and sialyl Lewis a. Immunohistochemistry was performed following standard procedures with antigenic retrieval. A multivariate statistical analysis with Principal Component (PCA) and Kendall-tau correlation was applied. Results: Malignant samples expressed MUC2 in 84.4% of cases, MUC1 in 70%, AGP in 68%, Lewis x in 57%, sialyl Lewis x in 31%, Lewis y in 43% and sialyl Lewis a in 88.5%. All antigens were also present in benign and normal tissues although progression to malignancy showed an increased expression of Lewis y, sialyl Lewis x and AGP and a decreased expression of MUC2 and Lewis x. In malignant samples, MUC1 mucin expression was increased compared to benign and normal tissues (P<0.04). Also, a statistically significant correlation between sialyl Lewis x and Lewis y (tau=0.4606) was found in colorectal cancer. Conclusions: This study demonstrates that MUC1 mucin, AGP, Lewis y and sialyl Lewis x are over expressed in colorectal cancer, whereas a decrease mainly in Lewis x and MUC2 mucin is observed. Further studies are needed in order to correlate these findings with clinical outcomes.