Immunohistochemical Analysis of Sialic Acid and Fucose Composition in Human Colorectal Adenocarcinoma

The expression of different sialoglycoconjugates and fucoglycoconjugates in normal mucosa and adenocarcinoma samples from 43 colorectal cancer patients was investigated by using specific lectins and applying a semiquantitative analysis. A pronounced decrease in the intracellular binding of the Maackia amurensis lectin, which recognizes α(2,3)-linked sialic acid residues, was found in the tumoral tissue. In contrast, a significant increase in the staining with the Sambucus nigra lectin (SNA I), which binds to α(2,6)-linked sialic acid residues, was detected in the epithelial cells as well as in the mucins from tumors. No significant differences in the reactivity with the Aleuria aurantia lectin, which recognizes the sequence Fuc(α1,6)GlcNAc, between normal and malignant colorectal tissues were detected. Furthermore, the correlation between lectin-binding profiles and the prognosis of colorectal cancer patients was examined. After an average postoperative follow-up period of 31 months, patients with tumors showing a strong SNA I staining presented a greater probability of disease recurrence. This result suggests that the intensity of staining with SNA I could be a valid parameter for predicting recurrence in colorectal cancer.