title: LIGHT sensitizes IFN-gamma-mediated apoptosis of HT-29 human carcinoma cells through both death receptor and mitochondria pathways.
abstract: LIGHT [homologous to lymphotoxins, shows inducible expression, and competes with herpes simplex virus glycoprotein D for herpes virus entry mediator (HVEM/TR2)] is a new member of TNF superfamily. The HT-29 colon cancer cell line is the most sensitive to LIGHT-induced, IFNg-mediated apoptosis among the cell lines we have examined so far. Besides downregulation of Bcl-XL, upregulation of Bak, and activation of both PARP [poly (ADP-ribose) polymerase] and DFF45 (DNA fragmentation factor), LIGHT-induced, IFNg-mediated apoptosis of HT-29 cells involves extensive caspase activation. Caspase-8 and caspase-9 activation, as shown by their cleavages appeared as early as 24 h after treatment, whereas caspase-3 and caspase-7 activation, as shown by their cleavages occurred after 72 h of LIGHT treatment. Caspase-3 inhibitor Z-DEVD-FMK (benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone) and a broad range caspase inhibitor Z-VAD-FMK (benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone) were able to block LIGHT-induced, IFNg-mediated apoptosis of HT-29 cells. The activity of caspase-3, which is one of the major executioner caspases, was found to be inhibited by both Z-DEVD-MFK and Z-VAD-FMK. These results suggest that LIGHT-induced, IFNg-mediated apoptosis of HT-29 cells is caspase-dependent, and LIGHT signaling is mediated through both death receptor and mitochondria pathways.
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, the University of Michigan, Ann Arbor, MI 48109-0934, USA. manchaoz@umich.edu
authors.forename: Man Chao
authors.initials: MC
authors.lastname: Zhang
authors.forename: Hong Peng
authors.initials: HP
authors.lastname: Liu
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Demchik
authors.forename: Yi Fan
authors.initials: YF
authors.lastname: Zhai
authors.forename: Da Jun
authors.initials: DJ
authors.lastname: Yang
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism* / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism* / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein
chemical_list: D000590:Amino Acid Chloromethyl Ketones; C494772:BAK1 protein, human; C494811:BCL2L1 protein, human; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D008565:Membrane Proteins; D009842:Oligopeptides; D019253:Proto-Oncogene Proteins c-bcl-2; D018124:Receptors, Tumor Necrosis Factor; C505914:TNFSF14 protein, human; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14; D014409:Tumor Necrosis Factor-alpha; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D007371:Interferon-gamma; D020169:Caspases