title: Adenovirus E1A reverses the resistance of normal primary human lung fibroblast cells to TRAIL through DR5 upregulation and caspase 8-dependent pathway.
abstract: Expression of the adenovirus serotype 5 (Ad5) E1A enhances tumor cells to apoptosis by TNF-alpha, Fas-ligand and TNF-related apoptosis-inducing ligand (TRAIL). In this study, we found that E1A expression reversed the resistance of normal primary human lung fibroblast cells (P-HLF) to TRAIL-induced apoptosis. Furthermore, TRAIL dramatically induced apoptosis of P-HLF cells that expressed E1A following either infection with Ad-E1A or transfection with pcDNA3-E1A. Further results demonstrated that E1A specifically upregulated DR5 levels but had nearly no effect on the levels of DR4. E1A dramatically upregulated the exogenous TRAIL, and then increased a substantial amount of TRAIL on the surface of P-HLF cells treated with the expression vectors, both Ad-TRAIL and pIRES-EGFP-TRAIL. The dominant negative FADD mutation (FADD-DN) results revealed that the apoptosis in Ad-E1A and Ad-TRAIL coinfected P-HLF cells was completely blocked following inhibition of the death receptors-associated apoptosis-inducing molecules FADD. Moreover, the caspase 8 inhibitor (Z-IETD-FMK) could efficiently block caspase 8 activation and resulted in inhibition of caspase 3 activation and cleavage. However, The caspase 9 specific inhibitor (Z-LEHD-FMK) could not counteract the synergistic effect of TRAIL-induced apoptosis in combination with E1A, and caspase 3 activation and cleavage were not inhibited by Z-LEHD-FMK. Thus, our results suggest that adenovirus E1A sensitizes P-HLF cells to TRAIL-induced apoptosis involving DR5 upregulation and the caspase 8-dependent pathway. These findings provide the first direct evidence for molecular mechanisms of adenovirus E1A gene products to sensitize normal cells to TRAIL-mediated apoptosis.
authors.affiliation: Laboratory of Molecular Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei Province, P. R. China.
authors.forename: Huabin
authors.initials: H
authors.lastname: Zhu
authors.forename: Weifang
authors.initials: W
authors.lastname: Ling
authors.forename: Baoli
authors.initials: B
authors.lastname: Hu
authors.forename: Yue
authors.initials: Y
authors.lastname: Su
authors.forename: Songbo
authors.initials: S
authors.lastname: Qiu
authors.forename: Wei
authors.initials: W
authors.lastname: Xiao
authors.forename: Yipeng
authors.initials: Y
authors.lastname: Qi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D053181:Caspase 8; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053200:Fas-Associated Death Domain Protein; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000166:cytology* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D008562:Membrane Glycoproteins; D009842:Oligopeptides; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; C403753:benzyloxycarbonyl-isoleucyl-glutamyl-threonyl-aspartic acid fluoromethyl ketone; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases