Purpose: One of the typical modifications on the surface of cancer cells is sialylation of terminal carbohydrates. The expression of several types of sialylation of glycoconjugates was investigated in colorectal cancer.
Methods: The cancer tissue specimens obtained from 65 colorectal cancer patients were stained with sialic acid-binding lectins from Maackia amurensis (MAM), Sambucus sieboldiana (SSA), Maackia amurensis agglutinin (MAA) and monoclonal antibodies, and compared with their clinicopathological features.
Results: Cancer tissue specimens from 44.6% of patients had positive staining with MAM, which recognized α2,3sialylated type 2 chain (NeuAcα2,3Galβ1,4GlcNAcβR) structures, but normal colorectal mucosa showed only weak staining with MAM was observed. More lymph node metastases and lymphatic invasion were seen in patients with positive staining with MAM (P < 0.01), while not with other lectins or antibodies that recognized sialylated glycoconjugates or sialyl Lewis-related antigens. The five-year survival rate of patients with MAM-positive staining was significantly lower than that with MAM-negative staining when including T0-1 cases, but there was no difference in cases with T2-4. There was no difference in the patients' survival rates when the tissues were stained with MAA, SSA or PNA lectins.
Conclusion: α2,3Sialylated type 2 chain structures were predominantly expressed in colorectal tissues associated with the malignant transformation, in particular, with lymphatic spread of distal colorectal adenocarcinomas.