title: Apoptosis induced by hepatitis B virus X protein in a CCL13-HBx stable             cell line.
abstract: The hepatitis B virus X protein (HBx) critically modulates cell growth by             inducing apoptosis or proliferation. We sought to clarify whether HBx-mediated             apoptosis in a CCL13 stable cell line (Chang-HBx) with inducible HBx expression             proceeds through the extrinsic (death receptor-mediated) and/or intrinsic (mitochondrial-mediated)             pathways of apoptosis. We used western blotting, cell viability assays, terminal             deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, caspase             activity assays, JC-1 staining and DNA fragmentation analysis to study the role             of HBx in apoptosis. The expression of the pro-apoptotic proteins Bax and Bad             and the release of cytochrome c also increased slightly upon HBx induction. JC-1             staining showed a loss of mitochondrial membrane potential upon HBx induction.             Additionally, induction of HBx increased the levels of cleaved caspase-9 (intrinsic             pathway), caspase-8 (extrinsic pathway) and the common effector caspase-3 as measured             by western blotting. This elevation of cleaved caspase-8 or caspase-3 and caspase-9             or caspase-3 decreased in the presence of caspase-8 inhibitor Z-IETD-FMK or caspase-9             inhibitor Z-LEHD-FMK, respectively. Both inhibitors also rescued cell growth,             and the caspase-8 inhibitor Z-IETD-FMK prevented apoptotic phenomena including             the TUNEL signal. DNA fragmentation analysis showed that these phenomena were             not detected in the presence of higher concentration of inhibitors. Our data suggest             that HBx induces apoptosis through both extrinsic and intrinsic pathways.
authors.affiliation: Department of Life Science, Tunghai University, Taichung, Taiwan, ROC.
authors.forename: Chan-Yen
authors.initials: CY
authors.lastname: Kuo
authors.forename: Ju-I
authors.initials: JI
authors.lastname: Tsai
authors.forename: Tzu-Yu
authors.initials: TY
authors.lastname: Chou
authors.forename: Man-Jung
authors.initials: MJ
authors.lastname: Hung
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Wu
authors.forename: Shih-Lan
authors.initials: SL
authors.lastname: Hsu
authors.forename: Guang-Yuh
authors.initials: GY
authors.lastname: Hwang
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D004789:Enzyme Activation; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D018945:Monocyte Chemoattractant Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D015534:Trans-Activators / Q000096:biosynthesis* / Q000235:genetics; D015533:Transcriptional Activation; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D051017:Apoptosis Regulatory Proteins; C099677:CCL13 protein, human; D018945:Monocyte Chemoattractant Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9