Regulatory roles of altered N- and O-glycosylation of CD45 in galectin-1-induced cell death in human diffuse large B cell lymphoma

To clarify the functions of CD45 N- and O-glycans in diffuse large B cell lymphoma (DLBCL), we analyzed the antiproliferative effects of bovine galectin-1 (beta-galactoside-binding lectin-1), which reacts with CD45 N-glycans and O-glycans, on human lymphoma cells. Bovine galectin-1 induced cell death of the DLBCL cell line HBL-2 in vitro. Swainsonine (SW) is a potent inhibitor of alpha-mannosidase II which catalyzes the synthesis of complex type N-linked oligosaccharides, and benzyl-GalNAc (BZGalNAc) is a potent inhibitor of O-glycosylation. Treatment with SW or BZGalNAc prevented cell death of HBL-2 cells by galectin-1. Western blot analysis revealed SW treatment reduced the molecular weight by about 5 kDa of one isoform at 190 kDa among three isoforms of CD45 which have N-linked oligosaccharide ligands for galectin-1. BZGalNAc treatment reduced the molecular weight of another isoform by about 15 kDa. These data suggest that the amount of CD45 N-glycans or O-glycans was reduced by SW and BZGalNAc treatment, respectively, and that reduction of CD45 N-glycans or O-glycans may prevent the interaction between CD45 and galectin-1. Alteration in CD45 N-glycans or O-glycans may regulate cell death of lymphoma cells through the interaction between CD45 N-glycans or O-glycans and galectin-1 in DLBCL.