Regulatory roles of N-glycosylation of immunoglobulin M in CD40-CD40L-mediated cell survival of human diffuse large B cell lymphoma.
L-PHA reactive oligosaccharides are found on the surface of HBL-2 cells, a lymphoma cell line, established from a human diffuse large B cell lymphoma (DLBCL). Swainsonine (SW) is a potent inhibitor of alpha-mannosidase II which catalyzes the biosynthesis of complex type N-linked oligosaccharides in human cells. CD40L stimulation of HBL-2 cells leads to their prolonged survival. Reduction in the expression of N-linked oligosaccharides, including L-PHA reactive oligosaccharides, on the cell surface by SW treatment resulted in enhancement of HBL-2 cell survival by CD40L stimulation. From an Annexin V assay the enhancement of CD40L-mediated HBL-2 cell survival by SW treatment may have resulted from anti-necrotic effects after 48 h of incubation. Bcl-2 enzyme linked immuno sorbent assay (ELISA) data showed that the expression of bcl-2 protein was enhanced by CD40L stimulation alone and also by CD40L stimulation along with SW treatment. However, there were no significant differences in the amount of bcl-2 protein with these treatments. Therefore, the enhancement of CD40L-mediated cell survival by SW treatment did not depend on the enhancement of bcl-2 protein expression. Furthermore, SW treatment of HBL-2 cells led to degradation of the heavy chain of IgM and rescued HBL-2 cells from anti-IgM-induced growth inhibition. Anti-IgM induced growth inhibition of HBL-2 cells prevented the inhibition of cell death by CD40L. From the present results it is possible that reduction of N-glycosylation of the heavy chain of IgM by SW treatment may reduce anti-IgM-induced growth inhibition, and reduction in anti-IgM-induced growth inhibition due to altered N-glycosylation may enhance CD40-CD40L-mediated cell survival through TRAF2 which interacts with both IgM and CD40 in HBL-2 cells.
Suzuki
Osamu
O
Fukushima Medical University, School of Medicine, Department of Pathology, Fukushima 960-1295, Japan. osuzuki@cc.fmu.ac.jp
Nozawa
Yoshihiro
Y
Abe
Masafumi
M
D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D019013:CD40 Antigens / Q000378:metabolism*; D023201:CD40 Ligand / Q000378:metabolism / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology / Q000378:metabolism*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017026:Swainsonine / Q000494:pharmacology; D047992:TNF Receptor-Associated Factor 2 / Q000378:metabolism
D000911:Antibodies, Monoclonal; D019013:CD40 Antigens; D007075:Immunoglobulin M; D019253:Proto-Oncogene Proteins c-bcl-2; D047992:TNF Receptor-Associated Factor 2; D023201:CD40 Ligand; D017026:Swainsonine