title: 8-Chloro-adenosine sensitizes a human hepatoma cell line to TRAIL-induced apoptosis by caspase-dependent and -independent pathways.
abstract: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor (TNF) super-family, induces apoptosis in various cancer cells with little or no effect on normal cells. 8-Chloro-adenosine (8-Cl-Ado) is a potential anti-cancer chemical agent now in clinical trail phase II, though its molecular mechanism remains poorly understood. In the present study, we report that 8-Cl-Ado can promote TRAIL killing activity in the hepatoma cell line BEL-7402 in dose- and time-dependent manner when jointly used in vitro. We showed that the expression of death receptor DR5, but not DR4 was up-regulated and the decoy receptor DcR1 was down-regulated in the cells treated with 8-Cl-Ado and the recombinant soluble TRAIL (rsTRAIL, 95-281 a.a.). Further experiments demonstrated that caspase-family inhibitor z-VAD-fmk prevented the cells from apoptosis induced by co-treatment with 8-Cl-Ado and rsTRAIL for 6 h, however, apoptosis occurred in the cells cultured for 24 h, suggesting that co-treatment induce a caspase-dependent and -independent signaling pathway in the BEL-7402 cells. This phenomenon was confirmed by cleavage analysis of caspase-3 and poly(ADP-ribose) polymerase (PARP), and ROS (reactive oxygen species) assay, respectively. Moreover, transcriptional activity test showed that NF-kappaB was inhibited in the BEL-7402 cells during co-treatment. Our results provided evidence for the first time that 8-Cl-Ado sensitizes the human hepatoma cells BEL-7402 to rsTRAIL-induced apoptosis by up-regulating DR5 expression, inactivating the NF-kappaB activity, and signaling by the caspase-dependent and -independent pathway.
authors.affiliation: National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, PR China.
authors.forename: Mingjie
authors.initials: M
authors.lastname: Wang
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Liu
authors.forename: Shilian
authors.initials: S
authors.lastname: Liu
authors.forename: Dexian
authors.initials: D
authors.lastname: Zheng
mesh_terms: D015762:2-Chloroadenosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D001483:Base Sequence; D006528:Carcinoma, Hepatocellular; D020169:Caspases / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D017931:DNA Primers; D006801:Humans; D008562:Membrane Glycoproteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D017931:DNA Primers; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D015762:2-Chloroadenosine; D020169:Caspases; C075440:8-chloroadenosine