title: Transfection of poly(I:C) can induce reactive oxygen species-triggered apoptosis and interferon-β-mediated growth arrest in human renal cell carcinoma cells via innate adjuvant receptors and the 2-5A system.
abstract: BACKGROUND
  Synthetic double-stranded RNA poly(I:C) is a useful immune adjuvant and exhibits direct antitumor effects against several types of cancers. In this study, we elucidated the mechanisms underlying the effects induced in poly(I:C)-transfected human renal cell carcinoma (RCC) cells.
  
  
  RESULTS
  In contrast to the lack of an effect of adding poly(I:C), poly(I:C) transfection drastically decreased RCC cell viability. Poly(I:C) transfection induced reactive oxygen species (ROS)-dependent apoptosis in RCC cells and decreased the mitochondrial membrane potential (ΔΨm). Treatment with N-acetyl-L-cysteine (NAC), a ROS scavenger, suppressed apoptosis and restored the ΔΨm. Although the levels of phosphorylated γH2A.X, an indicator of DNA damage, increased in poly(I:C)-transfected RCC cells, NAC treatment decreased their levels, suggesting ROS-mediated DNA damage. Furthermore, poly(I:C) transfection increased the levels of phosphorylated p53, NOXA, and tBid. Immunoblots and assays with a panel of caspase inhibitors revealed that poly(I:C) transfection-induced apoptosis was dependent on caspase-8 and -9, as well as caspase-2. Alternatively, poly(I:C) transfection increased mRNA expression of interferon (IFN)-β, and treatment with IFN-β suppressed growth of RCC cells without apoptosis. In addition, cyclinD1 and c-Myc expression decreased in poly(I:C)-transfected RCC cells. Moreover, RNA interference experiments revealed that poly(I:C) transfection exerted apoptotic effects on RCC cells through innate adjuvant receptors and the 2-5A system, the latter of which induces apoptosis in virus-infected cells.
  
  
  CONCLUSIONS
  These results suggest that poly(I:C) transfection induced two types of effects against RCC cells such as apoptosis, as a result of ROS-mediated DNA damage, and IFN-β-mediated growth arrest, both of which were exerted via innate adjuvant receptors and the 2-5A system.
authors.forename: Nanae
authors.initials: N
authors.lastname: Harashima
authors.forename: Takafumi
authors.initials: T
authors.lastname: Minami
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Uemura
authors.affiliation: Department of Immunology, Shimane University Faculty of Medicine, 89-1 Enya-cho, Izumo, Shimane 693-8501, Japan. haramamo@med.shimane-u.ac.jp.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Harada
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002292:Carcinoma, Renal Cell / Q000188:drug therapy* / Q000473:pathology*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D004722:Endoribonucleases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D016899:Interferon-beta / Q000378:metabolism; D007680:Kidney Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D011070:Poly I-C / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014162:Transfection
chemical_list: D000970:Antineoplastic Agents; D017382:Reactive Oxygen Species; D016899:Interferon-beta; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease; D011070:Poly I-C; D000111:Acetylcysteine