title: Differential involvement of Bax and Bak in TRAIL-mediated apoptosis of leukemic T cells.
abstract: TRAIL-induced apoptosis has been considered a promising therapeutic approach for tumors that are resistant to chemotherapy, which is usually mediated via mitochondrial apoptotic cascades. Recent studies have shown that in certain cancer cells, TRAIL-mediated apoptosis is also dependent on mitochondrial involvement, suggesting that similar mechanisms of resistance to chemotherapy might be implicated in the resistance of tumor cells to TRAIL. We have used TRAIL-resistant leukemic cells that are deficient in both Bax and Bak to determine the roles of these Bcl-2 members in TRAIL-mediated apoptosis. Exposure of these cells to TRAIL did not have an impact on cell viability, although it induced the processing of caspase-3 to its active p20 subunit. The activity of the p20 caspase-3 appeared to be inhibited as no autoprocessing of this p20 subunit or cleavage of known caspase-3 substrates were detected. Also, in the absence of Bax and Bak, no release of mitochondrial apoptogenic proteins was observed following TRAIL treatment. Adenoviral transduction of the Bax, but not the Bak gene, to the Bax/Bak-deficient leukemic cells rendered them TRAIL-sensitive as assessed by enhanced apoptotic death and caspase-3 processing. These findings demonstrate preferential utilization of Bax over Bak in leukemic cell response to specific apoptotic stimulation.
authors.affiliation: Department of Pathology, The University of Pittsburgh School of Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: J
authors.initials: J
authors.lastname: Han
authors.forename: L A
authors.initials: LA
authors.lastname: Goldstein
authors.forename: B R
authors.initials: BR
authors.lastname: Gastman
authors.forename: A
authors.initials: A
authors.lastname: Rabinovitz
authors.forename: G-Q
authors.initials: GQ
authors.lastname: Wang
authors.forename: B
authors.initials: B
authors.lastname: Fang
authors.forename: H
authors.initials: H
authors.lastname: Rabinowich
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007938:Leukemia / Q000378:metabolism* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein
chemical_list: D051017:Apoptosis Regulatory Proteins; C494772:BAK1 protein, human; C494826:BAX protein, human; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases