title: Caspase 8-dependent sensitization of cancer cells to TRAIL-induced apoptosis following reovirus-infection.
abstract: TRAIL (TNF-related apoptosis-inducing ligand) induces apoptosis in susceptible cells by binding to death receptors 4 (DR4) and 5 (DR5). TRAIL preferentially induces apoptosis in transformed cells and the identification of mechanisms by which TRAIL-induced apoptosis can be enhanced may lead to novel cancer chemotherapeutic strategies. Here we show that reovirus infection induces apoptosis in cancer cell lines derived from human breast, lung and cervical cancers. Reovirus-induced apoptosis is mediated by TRAIL and is associated with the release of TRAIL from infected cells. Reovirus infection synergistically and specifically sensitizes cancer cell lines to killing by exogenous TRAIL. This sensitization both enhances the susceptibility of previously resistant cell lines to TRAIL-induced apoptosis and reduces the amount of TRAIL needed to kill already sensitive lines. Sensitization is not associated with a detectable change in the expression of TRAIL receptors in reovirus-infected cells. Sensitization is associated with an increase in the activity of the death receptor-associated initiator caspase, caspase 8, and is inhibited by the peptide IETD-fmk, suggesting that reovirus sensitizes cancer cells to TRAIL-induced apoptosis in a caspase 8-dependent manner. Reovirus-induced sensitization of cells to TRAIL is also associated with increased cleavage of PARP, a substrate of the effector caspases 3 and 7.
authors.affiliation: Department of Neurology, University of Colorado Health Sciences, Denver, Colorado, CO 80262, USA.
authors.forename: P
authors.initials: P
authors.lastname: Clarke
authors.forename: S M
authors.initials: SM
authors.lastname: Meintzer
authors.forename: A C
authors.initials: AC
authors.lastname: Spalding
authors.forename: G L
authors.initials: GL
authors.lastname: Johnson
authors.forename: K L
authors.initials: KL
authors.lastname: Tyler
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000502:physiology*; D004317:Doxorubicin / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000494:pharmacology* / Q000502:physiology; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000821:virology*; D030102:Orthoreovirus, Mammalian / Q000502:physiology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D012334:RNA, Neoplasm / Q000096:biosynthesis; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000235:genetics; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology* / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D012334:RNA, Neoplasm; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D004317:Doxorubicin; D011065:Poly(ADP-ribose) Polymerases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases