title: Isoproterenol Enhances Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand-Induced Apoptosis in Human Embryonic Kidney Cells through Death Receptor 5 up-Regulation.
abstract: OBJECTIVE
  Chronic impairment of β-adrenergic receptor signaling increases cardiac apoptosis, hypertrophy and fibrosis. The aim of this study was to investigate whether isoproterenol (ISO), an agonist of the adrenergic receptor, can enhance tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in human embryonic kidney (HEK) 293 cells.
  
  
  METHODS
  HEK 293 cells were treated with ISO and/or TRAIL for 24 hours. Cell viability was evaluated by microscopy and an established viability assay, and apoptotic cell death was analyzed by staining with fluorescein isothiocynate-annexin-V/propidium iodide (PI) and caspase activation. To confirm the mechanism of cell death induced by co-treatment with ISO and TRAIL, expression of TRAIL receptor 2 (death receptor 5, DR5) was evaluated by immunoblotting.
  
  
  RESULTS
  Although ISO or TRAIL treatment decreased HEK 293 cell viability by 13% and 17%, respectively, co-treatment with ISO and TRAIL resulted in a markedly higher death rate of 35% after 24 hours. Increases were evident in early apoptotic cells (i.e., annexin-V positive/PI negative; 19.4%), late apoptotic cells (i.e., annexin-V positive/PI positive; 6.3%) and dead cells (i.e., annexin-V negative/PI positive; 1.1%) when cells were co-treated with ISO and TRAIL, compared to cells treated with either ISO or TRAIL. In addition, marked increases of cleaved cas-3, cleaved poly (adenosine diphosphate-ribose) polymerase and DR5 were observed in HEK 293 cells co-treated with ISO and TRAIL.
  
  
  CONCLUSIONS
  Treatments combining ISO with TRAIL may be responsible for death of HEK 293 cells through DR5 up-regulation. Activation of adrenergic receptors is responsible for the synergistic cell death observed with TRAIL.
authors.affiliation: Cell Therapy and Tissue Engineering Center, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Young Woo
authors.initials: YW
authors.lastname: Eom
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Ha Yun
authors.initials: HY
authors.lastname: Jung
authors.affiliation: Cell Therapy and Tissue Engineering Center, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Oh
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Jun-Won
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Min-Soo
authors.initials: MS
authors.lastname: Ahn
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Youn
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Sung Gyun
authors.initials: SG
authors.lastname: Ahn
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Jang Young
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Seung-Hwan
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Junghan
authors.initials: J
authors.lastname: Yoon
authors.affiliation: Cardiology Division, Department of Internal Medicine, Wonju College of Medicine, Yonsei University, Wonju, Korea.
authors.forename: Byung-Su
authors.initials: BS
authors.lastname: Yoo
keywords: Apoptosis; Death receptor 5; Isoproterenol; TNF-related apoptosis-inducing ligand