title: Down-regulation of cFLIP following reovirus infection sensitizes human ovarian cancer cells to TRAIL-induced apoptosis.
abstract: Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) shows promise as a chemotherapeutic agent. However, many human cancer cells are resistant to killing by TRAIL. We have previously demonstrated that reovirus infection increases the susceptibility of human lung (H157) and breast (ZR75-1) cancer cell lines to TRAIL-induced apoptosis. We now show that reovirus also increases the susceptibility of human ovarian cancer cell lines (OVCAR3, PA-1 and SKOV-3) to TRAIL-induced apoptosis. Reovirus-induced increases in susceptibility of OVCAR3 cells to TRAIL require virus uncoating and involve increased activation of caspases 3 and 8. Reovirus infection results in the down-regulation of cFLIP (cellular FLICE inhibitory protein) in OVCAR3 cells. Down-regulation of cFLIP following treatment of OVCAR3 cells with antisense cFLIP oligonucleotides or PI3 kinase inhibition also increases the susceptibility of OVCAR3 cells to TRAIL-induced apoptosis. Finally, over-expression of cFLIP blocks reovirus-induced sensitization of OVCAR3 cells to TRAIL-induced apoptosis. The combination of reovirus and TRAIL thus represents a promising new therapeutic approach for the treatment of ovarian cancer.
authors.affiliation: Department of Neurology, University of Colorado Health Sciences Center, 4200 East 9th Avenue, Box B182, Denver, Colorado 80262, USA. penny.clarke@uchsc.edu
authors.forename: Penny
authors.initials: P
authors.lastname: Clarke
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Tyler
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism*; D053181:Caspase 8 / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005260:Female; D006801:Humans; D012089:Mammalian orthoreovirus 3 / Q000472:pathogenicity*; D008928:Mitochondria / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology* / Q000821:virology; D011994:Recombinant Proteins / Q000494:pharmacology; D012088:Reoviridae Infections / Q000378:metabolism* / Q000473:pathology*; D015398:Signal Transduction / Q000187:drug effects; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*
chemical_list: D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; C505530:CASP8 protein, human; D053181:Caspase 8