title: Requirement for aspartate-cleaved bid in apoptosis signaling by DNA-damaging anti-cancer regimens.
abstract: Lymphoid malignancies can escape from DNA-damaging anti-cancer drugs and gamma-radiation by blocking apoptosis-signaling pathways. How these regimens induce apoptosis is incompletely defined, especially in cells with nonfunctional p53. We report here that the BH3-only Bcl-2 family member Bid is required for mitochondrial permeabilization and apoptosis induction by etoposide and gamma-radiation in p53 mutant T leukemic cells. Bid is not transcriptionally up-regulated in response to these stimuli but is activated by cleavage on aspartate residues 60 and/or 75, which are the targets of caspase-8 and granzyme B. Bid activity is not inhibitable by c-Flip(L), CrmA, or dominant negative caspase-9 and therefore is independent of inducer caspase activation by death receptors or the mitochondria. Caspase-2, which has been implicated as inducer caspase in DNA damage pathways, appeared to be processed in response to etoposide and gamma-radiation but downstream of caspase-9. Knock down of caspase-2 by short interfering RNA further excluded its role in Bid activation by DNA damage. Caspase-2 was implicated in the death receptor pathway however, where it contributed to effector caspase processing downstream of inducer caspases. Granzyme B-specific serpins could not block DNA damage-induced apoptosis, excluding a role for granzyme B in the generation of active Bid. We conclude that Bid, cleaved by an undefined aspartate-specific protease, can be a key mediator of the apoptotic response to DNA-damaging anticancer regimens.
authors.affiliation: Division of Immunology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
authors.forename: Arlette B
authors.initials: AB
authors.lastname: Werner
authors.forename: Stephen W G
authors.initials: SW
authors.lastname: Tait
authors.forename: Evert
authors.initials: E
authors.lastname: de Vries
authors.forename: Eric
authors.initials: E
authors.lastname: Eldering
authors.forename: Jannie
authors.initials: J
authors.lastname: Borst
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001224:Aspartic Acid / Q000378:metabolism*; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000378:metabolism*; D053143:Caspase 2; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005047:Etoposide / Q000494:pharmacology; D005434:Flow Cytometry; D005720:Gamma Rays; D005799:Genes, Dominant; D053804:Granzymes; D006801:Humans; D015151:Immunoblotting; D019169:Jurkat Cells; D015458:Leukemia, T-Cell / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D034741:RNA, Small Interfering / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D012697:Serine Endopeptidases / Q000378:metabolism; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; C494815:Bid protein, mouse; D002352:Carrier Proteins; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D001224:Aspartic Acid; D005047:Etoposide; D045304:Cytochromes c; C509213:GZMB protein, human; D053804:Granzymes; C509214:Gzmb protein, mouse; D012697:Serine Endopeptidases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053143:Caspase 2; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases