title: Regulation of Apo2L/tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in thyroid carcinoma cells.
abstract: Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)/Apo2 ligand selectively kills neoplastic cells, including thyroid carcinoma cells (Mitsiades et al: Thyroid carcinoma cells are resistant to FAS-mediated apoptosis but sensitive to tumor necrosis factor-related apoptosis-inducing ligand. Cancer Res 2000, 60:4122-41299). We investigated the mechanisms regulating Apo2L/TRAIL-induced apoptosis in thyroid carcinoma cells, as well as the impact of insulin-like growth factor (IGF)-1, interferon-gamma, and TNF-alpha. We found that the emergence of resistance to Apo2L/TRAIL, after prolonged incubation with this cytokine, was associated with increased levels of FLICE inhibitory protein (FLIP), and was overcome by cycloheximide and bisindolylmaleimide, that specifically down-regulated FLIP expression, as well as by transfection of a FLIP anti-sense oligonucleotide. IGF-1 activated Akt; up-regulated the caspase inhibitors FLIP, cIAP-2, XIAP, and survivin; and attenuated Apo2L/TRAIL-induced apoptosis. This effect was inhibited by the IGF-1 receptor neutralizing antibody aIR3, the PI-3K inhibitor wortmannin, and the heat shock protein-90 chaperone inhibitor geldanamycin. Transfection of constitutively active Akt protected from TRAIL. Conversely, interferon-gamma and TNF-alpha had a sensitizing effect. We conclude that FLIP may negatively regulate Apo2L/TRAIL-induced apoptosis in thyroid carcinomas. Microenvironmental paracrine survival factors, such as IGF-1, up-regulate caspase inhibitors, including FLIP, and protect from Apo2L/TRAIL in a PI-3K/Akt-dependent manner. T helper-1 cytokines and compounds that selectively abrogate the IGF-1 signaling pathway may be helpful adjunct agents in Apo2L/TRAIL-based anti-cancer therapeutic regimens.
authors.affiliation: Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114, USA. poulakiv@hotmail.com
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Poulaki
authors.forename: Constantine S
authors.initials: CS
authors.lastname: Mitsiades
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Kotoula
authors.forename: Sophia
authors.initials: S
authors.lastname: Tseleni-Balafouta
authors.forename: Avi
authors.initials: A
authors.lastname: Ashkenazi
authors.forename: Demetrios A
authors.initials: DA
authors.lastname: Koutras
authors.forename: Nicholas
authors.initials: N
authors.lastname: Mitsiades
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D053221:TNF-Related Apoptosis-Inducing Ligand; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D007334:Insulin-Like Growth Factor I