Anti-CD20-and B-cell receptor-mediated apoptosis: Evidence for shared intracellular signaling pathways

Item Type:	Article
Title:	Anti-CD20-and B-cell receptor-mediated apoptosis: Evidence for shared intracellular signaling pathways
Creators Name:	Mathas, S. and Rickers, A. and Bommert, K. and Doerken, B. and Mapara, M.Y.
Abstract:	Clinical administration of the anti-CD20 antibody IDEC-C2B8 can induce remission of low-grade B-cell lymphoma. Whereas it has been suggested that the main mechanisms of action are complement-mediated and antibody-dependent cell-mediated cytotoxicity, we demonstrate that monoclonal antibody IDEC-C2B8 is a strong inducer of apoptosis in CD20-positive B-cell lymphoma cell lines reflecting different stages of lymphomagenesis. Thus, CD20-dependent apoptosis was inducible in human surface IgM-positive Burkitt's lymphoma cell lines as well as in more mature surface IgM-negative B-cell lymphoma cell lines carrying the t(14;18) translocation. Furthermore, in Burkitt's lymphoma cell lines, we observed a striking correlation between anti-CD20- and B-cell receptor-mediated apoptosis with regard to sensitivity toward the apoptotic stimuli and the execution of the apoptotic pathway. Thus, induction of anti-CD20- or B-cell receptor-mediated apoptosis involved rapid up-regulation of the proapoptotic protein Bax. In addition, we show similar changes in the mRNA expression level of two early response genes, c-myc and Berg36, as well as activation of the mitogen-activated protein kinase family members p44 (extracellular signal-regulated kinase 1) and p42 (extracellular signal-regulated kinase 2) and activation of activator protein 1 (AP-1) DNA binding activity. These data support our hypothesis that both pathways are mediated in part by the same signal-transducing molecules. These results might help explain the resistance and regression of lymphomas to IDEC-C2B8 and give new insights in the signaling cascade after CD20 ligation.
Keywords:	Apoptosis, B-Cell Antigen Receptors, bcl-2-Associated X Protein, B-Lymphocytes, Burkitt Lymphoma, Butyrate Response Factor 1, Caspases, Cell Division, Cell Nucleus, CD20 Antigens, Cultured Tumor Cells, DNA, DNA-Binding Proteins, Flow Cytometry, Fluorescent Antibody Technique, Genetic Translocation, Immediate-Early Proteins, Immunoblotting, Immunoglobulin M, Messenger RNA, Mitogen-Activated Protein Kinase 1, Mitogen-Activated Protein Kinase 3, Mitogen-Activated Protein Kinases, Northern Blotting, Poly(ADP-ribose) Polymerases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-bcl-2, Proto-Oncogene Proteins c-myc, RNA, Signal Transduction, Sp1 Transcription Factor, Time Factors, Transcription Factor AP-1, Up-Regulation
Source:	Cancer Research
ISSN:	0008-5472
Publisher:	American Association for Cancer Research
Volume:	60
Number:	24
Page Range:	7170-7176
Date:	1 January 2000
Official Publication:	http://cancerres.aacrjournals.org/cgi/content/abstract/60/24/7170
PubMed:	View item in PubMed

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