The regulatory roles of cell surface sialylation and N-glycans in human B cell lymphoma cell adhesion to galectin-1

Surface sialylation and glycosylation of tumor cells is known to affect various biological phenomena. In the present study, we analyzed the regulatory roles of cell surface sialylation in cell adhesion to galectin-1 in the human diffuse large B cell lymphoma (DLBCL) cell line, HBL-2, and Burkitt's lymphoma cell line, HBL-8. Vibrio cholerae neuraminidase treatment enhanced HBL-2 cell adhesion to galectin-1, suggesting that sialic acid inhibits HBL-2 cell adhesion to galectin-1. The data from employing two different neuraminidases, Vibrio cholerae and Newcastle disease virus neuraminidase, showed that alpha2,6-linked sialic acid plays an important role in the inhibition of HBL-2 cell adhesion to galectin-1. In addition, neuraminidase treatment enhanced the cell adhesion to galectin-1 much more with the highly sialylated HBL-8 3G3 clone than with the hyposialylated HBL-8 3D2 clone. Flow cytometric analysis revealed the expression of partially sialylated L-PHA reactive oligosaccharides on the surfaces of HBL-2 cells. Swainsonine (SW) treatment also enhanced HBL-2 cell adhesion to galectin-1. These data indicate that SW treatment decreased sialylated L-PHA reactive oligosaccharides resulting in cell surface desialylation and leading to enhancement of cell adhesion to galectin-1. In conclusion, alteration of cell surface sialylation or N-glycan expression regulates cell adhesion to galectin-1 in human malignant lymphoma.