High expression of α 2, 3-linked sialic acid residues is associated with the metastatic potential of human gastric cancer

Background: Sialic acid, as a terminal saccharide residue on cell surface glycoconjugates, plays an important role in a variety of biological processes. However, the precise nature of the molecules in gastric cancers has not been unveiled nor documented to be of clinical relevance. Herein, we measured the expression of α 2, 3-linked sialic acid residues by using a specific lectin as well as the potential of invasion and metastasis of gastric cancer was analyzed. Methods: The expression of α 2, 3-linked sialic acid residues in 100 cases of gastric cancer samples was evaluated using Maackia amurensis leukoagglutinin (MAL) histochemical staining analysis. The assays of cytochemical staining and flow cytometry were employed to determine the MAL positive cells in the gastric cancer cell lines. The activities of invasion and migration were evaluated using the assays of cell adhesion and transwell chamber. Results: The staining of MAL in gastric cancer tissues showed that high levels of α 2, 3-linked sialic acid residues were closely associated with the invasive depth (P = 0.0003) and lymph node metastasis (P = 0.0441). In gastric adenocarcinoma cell lines, SGC-7901, the highly metastatic cell line, displayed the most positive reaction with MAL among the selected cell lines. The potential of invasion and migration was confirmed using the assays of adhesion and transwell chamber that SGC-7901 exhibited the high activity of adhesion to extracellular matrix (ECM) and penetration to Matrigel. Conclusion: These results suggested that high level of α 2, 3-linked sialic acid residues was associated with metastatic potential of gastric cancer cells.