Mechanism of LIGHT/interferon-gamma-induced cell death in HT-29 cells.
LIGHT is a member of tumor necrosis factor (TNF) superfamily, and previous studies have indicated that in the presence of interferon-gamma (IFN-gamma), LIGHT through LTbetaR signaling can induce cell death with features unlike classic apoptosis. In present study, we investigated the mechanism of LIGHT/IFN-gamma-induced cell death in HT-29 cells, where the cell death was profoundly induced when sub-toxic concentrations of LIGHT and IFN-gamma were co-treated. LIGHT/IFN-gamma-induced cell death was accompanied by DNA fragmentation and slight LDH release. This effect was not affected by caspase, JNK nor cathepsin B inhibitors, but was partially prevented by p38 mitogen-activated protein kinase (MAPK) and poly (ADP-ribose) polymerase (PARP) inhibitors, and abolished by aurintricarboxylic acid (ATA), which is an inhibitor of endonuclease and STATs signaling of IFN-gamma. Immunobloting reveals that LIGHT/IFN-gamma could induce p38 MAPK activity, Bak and Fas expression, but down-regulate Mcl-1. Besides, LIGHT/IFN-gamma could not activate caspase-3 and -9, but decreased mitochondrial membrane potential. Although LIGHT could not affect IFN-gamma-induced STAT1 phosphorylation and transactivation activity, which was required for the sensitization of cell death, survival NF-kappaB signaling of LIGHT was inhibited by IFN-gamma. These data suggest that co-presence of LIGHT and IFN-gamma can induce an integrated interaction in signaling pathways, which lead to mitochondrial dysfunction and mix-type cell death, not involving caspase activation.
Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Ying-Hsin
YH
Chang
Yee
Y
Chao
Shie-Liang
SL
Hsieh
Wan-Wan
WW
Lin
D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D007371:Interferon-gamma / Q000633:toxicity*; D053259:Lymphotoxin beta Receptor; D008562:Membrane Glycoproteins / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000633:toxicity*; D008928:Mitochondria / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D053323:Receptors, Tumor Necrosis Factor, Member 6b; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects*; D015534:Trans-Activators / Q000378:metabolism; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000633:toxicity*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D004268:DNA-Binding Proteins; C505697:LTBR protein, human; D053259:Lymphotoxin beta Receptor; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D011956:Receptors, Cell Surface; D018124:Receptors, Tumor Necrosis Factor; D053323:Receptors, Tumor Necrosis Factor, Member 6b; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; C505911:TNFRSF6B protein, human; C505914:TNFSF14 protein, human; D015534:Trans-Activators; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D048051:p38 Mitogen-Activated Protein Kinases