title: The tricyclodecan-9-yl-xanthogenate D609 triggers ceramide increase and enhances FasL-induced caspase-dependent and -independent cell death in T lymphocytes.
abstract: D609 is known to modulate death receptor-induced ceramide generation and cell death. We show that in Jurkat cells, non-toxic D609 concentrations inhibit sphingomyelin synthase and, to a lesser extent, glucosylceramide synthase, and transiently increase the intracellular ceramide level. D609 significantly enhanced FasL-induced caspase activation and apoptosis. D609 stimulated FasL-induced cell death in caspase-8-deficient Jurkat cells, indicating that D609 acts downstream of caspase-8. At high FasL concentration (500 ng/mL), cell death was significantly, but not completely, inhibited by zVAD-fmk, a broad-spectrum caspase inhibitor, indicating that FasL can activate both caspase-dependent and -independent cell death signaling pathways. FasL-induced caspase activation was abolished by zVAD-fmk, whereas ceramide production was only partially impaired. D609 enhanced caspase-independent ceramide increase and cell death in response to FasL. Also, D609 overcame zVAD-fmk-conferred resistance to a FasL concentration as low as 50 ng/mL and bypassed RIP deficiency. It is likely that mitochondrial events were involved, since Bcl-xL over-expression impaired D609 effects. In PHA-activated human T lymphocytes, D609 enhanced FasL-induced cell death in the presence or absence of zVAD-fmk. Altogether, our data strongly indicate that the inhibition of ceramide conversion to complex sphingolipids by D609 is accompanied by an enhancement of FasL-induced caspase-dependent and -independent cell death in T lymphocytes.
authors.affiliation: Team 4, Cancer Research Center of Toulouse, INSERM UMR1037, BP84225, 31432 Toulouse Cedex 4, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Milhas
authors.affiliation: Team 4, Cancer Research Center of Toulouse, INSERM UMR1037, BP84225, 31432 Toulouse Cedex 4, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Andrieu-Abadie
authors.affiliation: Team 4, Cancer Research Center of Toulouse, INSERM UMR1037, BP84225, 31432 Toulouse Cedex 4, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Levade
authors.affiliation: Team 4, Cancer Research Center of Toulouse, INSERM UMR1037, BP84225, 31432 Toulouse Cedex 4, France.|Department of Cell Biology, Hematology and Immunology, Faculty of Pharmaceutical Sciences, Paul Sabatier University (Toulouse III), 31062 Toulouse, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Benoist
authors.affiliation: Team 4, Cancer Research Center of Toulouse, INSERM UMR1037, BP84225, 31432 Toulouse Cedex 4, France.|Department of Cell Biology, Hematology and Immunology, Faculty of Pharmaceutical Sciences, Paul Sabatier University (Toulouse III), 31062 Toulouse, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Ségui
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001952:Bridged-Ring Compounds / Q000494:pharmacology*; D053181:Caspase 8 / Q000378:metabolism*; D061945:Caspase Inhibitors / Q000378:metabolism / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002518:Ceramides / Q000378:metabolism*; D053222:Fas Ligand Protein / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D019169:Jurkat Cells; D008928:Mitochondria / Q000378:metabolism; D009636:Norbornanes; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D013859:Thiocarbamates; D013871:Thiones / Q000494:pharmacology*; D051020:bcl-X Protein
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000970:Antineoplastic Agents; C494811:BCL2L1 protein, human; D001952:Bridged-Ring Compounds; D061945:Caspase Inhibitors; D002518:Ceramides; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D009636:Norbornanes; D013859:Thiocarbamates; D013871:Thiones; D051020:bcl-X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C046498:tricyclodecane-9-yl-xanthogenate; C505530:CASP8 protein, human; D053181:Caspase 8