title: beta-Ionone enhances TRAIL-induced apoptosis in hepatocellular carcinoma cells through Sp1-dependent upregulation of DR5 and downregulation of NF-kappaB activity.
abstract: beta-Ionone (ION), an end-ring analogue of beta-carotenoid, has been known to inhibit tumor cell growth and induce apoptosis in various types of cancer cells. Nevertheless, its apoptosis-related molecular mechanisms remain unclear. Here, we first investigated the molecular mechanisms by which ION sensitizes cancer cells to the therapeutic potential of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Notably, treatment with subtoxic concentrations of ION and TRAIL effectively inhibited cell viability in the hepatocellular carcinoma cell line Hep3B and other cancer cell lines such as colon carcinoma cell line HCT116 and leukemia cell line U937. Combined treatment with ION and TRAIL was also more effective in inducing DR5 expression, caspase activities, and apoptosis than treatment with either agent alone. ION-mediated sensitization to TRAIL was efficiently reduced by treatment with a chimeric blocking antibody or small interfering RNA specific for DR5. Electrophoretic mobility shift assay and a chromatin immunoprecipitation assay confirmed that ION treatment upregulates the binding of transcription factor Sp1 to its putative site within the DR5 promoter region, suggesting that Sp1 is an ION-responsive transcription factor. In addition, ION significantly increased hepatocellular carcinoma cell sensitivity to TRAIL by abrogating TRAIL-induced NF-kappaB activation and decreasing the expression of antiapoptotic proteins such as XIAP and IAP-1/2. Taken together, these data suggest that ION is a useful agent for TRAIL-based cancer treatments. Mol Cancer Ther; 9(4); 833-43. (c)2010 AACR.
authors.affiliation: Department of Marine Life Sciences, Jeju National University, Jeju 690-756, Republic of Korea.
authors.forename: Mun-Ock
authors.initials: MO
authors.lastname: Kim
authors.forename: Dong-Oh
authors.initials: DO
authors.lastname: Moon
authors.forename: Chang-Hee
authors.initials: CH
authors.lastname: Kang
authors.forename: Taeg Kyu
authors.initials: TK
authors.lastname: Kwon
authors.forename: Yung Hyun
authors.initials: YH
authors.lastname: Choi
authors.forename: Gi-Young
authors.initials: GY
authors.lastname: Kim
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000473:pathology*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D008113:Liver Neoplasms / Q000201:enzymology / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D045792:Norisoprenoids / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D053218:Receptors, Death Domain / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D016328:NF-kappa B; D045792:Norisoprenoids; D053218:Receptors, Death Domain; D016329:Sp1 Transcription Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C008157:beta-ionone; D020169:Caspases