title: The TRAIL apoptotic pathway mediates proteasome inhibitor induced apoptosis in primary chronic lymphocytic leukemia cells.
abstract: The proteasome inhibitors are a new class of antitumor agents. These inhibitors cause the accumulation of many proteins in the cell with the induction of apoptosis including TRAIL death receptors DR4 and DR5, but the role of the TRAIL apoptotic pathway in proteasome inhibitor cytotoxicity is unknown. Herein, we have demonstrated that the induction of apoptosis by the proteasome inhibitors, MG-132 and PS-341 (bortezomib, Velcade), in primary CLL cells and the Burkitt lymphoma cell line, BJAB, is associated with up-regulation of TRAIL and its death receptors, DR4 and DR5. In addition, FLICE-like inhibitory protein (c-FLIP) protein is decreased. MG-132 treatment increases binding of DR5 to the adaptor protein FADD, and causes caspase-8 activation and cleavage of pro-apoptotic BID. Moreover, DR4:Fc or blockage of DR4 and DR5 expression using RNA interference, which prevents TRAIL apoptotic signaling, blocks proteasome inhibitor induced apoptosis. MG-132 also increases apoptosis and DR5 expression in normal B-cells. However, when the proteasome inhibitors are combined with TRAIL or TRAIL receptor activating antibodies the amount of apoptosis is increased in CLL cells but not in normal B cells. Thus, activation of the TRAIL apoptotic pathway contributes to proteasome inhibitor induced apoptosis in CLL cells.
authors.affiliation: Manitoba Institute of Cell Biology, Cancer Care Manitoba, University of Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba.
authors.forename: Albert F
authors.initials: AF
authors.lastname: Kabore
authors.forename: Jinmie
authors.initials: J
authors.lastname: Sun
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Hu
authors.forename: Kristin
authors.initials: K
authors.lastname: McCrea
authors.forename: James B
authors.initials: JB
authors.lastname: Johnston
authors.forename: Spencer B
authors.initials: SB
authors.lastname: Gibson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004357:Drug Synergism; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000097:blood / Q000473:pathology; D007976:Leupeptins / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D008875:Middle Aged; D061988:Proteasome Inhibitors; D011719:Pyrazines / Q000494:pharmacology; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D001897:Boronic Acids; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D015853:Cysteine Proteinase Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D007976:Leupeptins; D008562:Membrane Glycoproteins; D061988:Proteasome Inhibitors; D011719:Pyrazines; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D000069286:Bortezomib; C510234:lexatumumab; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde