title: 5-allyl-7-gen-difluoromethoxychrysin enhances TRAIL-induced apoptosis in human lung carcinoma A549 cells.
abstract: BACKGROUND
  5-allyl-7-gen-difluoromethoxychrysin (AFMC) is a novel synthetic analogue of chrysin that has been reported to inhibit proliferation in various cancer cell lines. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anti-cancer agent.
  
  
  METHODS
  The cytotoxicity of A549 and WI-38 cells were determined using colorimetry. Apoptosis was detected by flow cytometry (FCM) after propidium iodide (PI) fluorescence staining and agarose gel electrophoresis. Caspase activities were evaluated using enzyme-linked immunosorbent assay (ELISA).The expressions of DR4 and DR5 were analyzed using FCM and western blot.
  
  
  RESULTS
  Subtoxic concentrations of AFMC sensitize human non-small cell lung cancer (NSCLC) A549 cells to TRAIL-mediated apoptosis. Combined treatment of A549 cells with AFMC and TRAIL significantly activated caspase-3, -8 and -9. The caspase-3 inhibitor zDEVD-fmk and the caspase-8 inhibitor zIETD-fmk blocked the apoptosis of A549 cells induced by co-treatment with AFMC and TRAIL. In addition, we found that treatment of A549 cells with AFMC significantly induced the expression of death receptor 5 (DR5). AFMC-mediated sensitization of A549 cells to TRAIL was efficiently reduced by administration of a blocking antibody or small interfering RNAs against DR5. AFMC also caused increase of the Sub-G1 cells by TRAIL treatment and increased the expression levels of DR5 in other NSCLC H460 and H157 cell lines. In contrast, AFMC-mediated induction of DR5 expression was not observed in human embryo lung WI-38 cells, and AFMC did not sensitize WI-38 cells to TRAIL-induced apoptosis.
  
  
  CONCLUSIONS
  AFMC synergistically enhances TRAIL-mediated apoptosis in NSCLC cells through up-regulating DR5 expression.
authors.affiliation: Changsha Health Vocational College, Changsha 410010, Hunan Province, China.
authors.forename: Zhao-Hui
authors.initials: ZH
authors.lastname: Xie
authors.forename: Mei-Fang
authors.initials: MF
authors.lastname: Quan
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Cao
authors.forename: Jian-Song
authors.initials: JS
authors.lastname: Zhang
mesh_terms: D019138:Antibodies, Blocking / Q000276:immunology / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*
chemical_list: C530100:5-allyl-7-gen-difluoromethylenechrysin; D019138:Antibodies, Blocking; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D005419:Flavonoids; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; C043561:chrysin; D020169:Caspases