title: Synergic carcinostatic effects of ascorbic acid and hyperthermia on Ehrlich ascites tumor cell.
abstract: OBJECTIVE
  In this study, we evaluated the carcinostatic effects of combined ascorbic acid (AsA) and a capacitive-resistive electric transfer (CRet) hyperthermic apparatus-induced hyperthermic treatment on Ehrlich ascites tumor (EAT) cells.
  
  
  METHODS
  EAT cells were exposed to various AsA (0-10 mM) concentrations for 1 h; they subsequently underwent CRet treatment for 15 min at 42 °C. Cell viability was assessed by the WST-8 assay 24 h after the combined treatment. Reactive oxygen species involvement was evaluated using catalase and tempol; caspase-3/7 activation was determined by their fluorescent substrates; cell proliferation were estimated by time-lapse observation. The effect on the cell cycle was analyzed by flow cytometry.
  
  
  RESULTS
  Combined AsA and CRet treatment synergistically suppressed cell viability compared with either treatment alone, and these synergistically carcinostatic effects were evident even at noncytotoxic concentrations of AsA alone (≤ 2 mM). The carcinostatic effects of combined AsA and CRet treatment were attenuated in a dose-dependent manner by catalase addition, but not by the superoxide anion radical scavenger tempol. Time-lapse observation revealed that combined AsA and CRet treatment activated caspase-3/7 at 10-24 h after treatment, accompanied by significant cell growth suppression. Cell cycle analysis revealed that the rate of sub-G1-phase (apoptotic) cells was drastically increased at 12 h and 24 h, and that the G2/M-phase cells gradually increased at 6-24 h after treatment.
  
  
  CONCLUSIONS
  These results indicate that combined AsA and CRet treatment synergistically inhibits EAT cell growth through G2/M arrest and apoptosis induction via H2O2 generation at lower AsA concentrations; this carcinostatic effect cannot be exerted by AsA alone.
authors.affiliation: Laboratory of Bioscience & Biotechnology for Cell Function Control, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, 562 Nanatsuka, Shobara, Hiroshima 727-0023, Jap.
authors.forename: Y
authors.initials: Y
authors.lastname: Saitoh
authors.affiliation: Laboratory of Bioscience & Biotechnology for Cell Function Control, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, 562 Nanatsuka, Shobara, Hiroshima 727-0023, Jap.
authors.forename: T
authors.initials: T
authors.lastname: Yoshimoto
authors.affiliation: Radioisotope Facilities for Medical Science, Life Science Research Center, Mie University, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kato
authors.affiliation: Department of Radiological Technology, Faculty of Health Sciences, Butsuryo College of Osaka, 3-33 Ohtorikita-machi, Sakai, Osaka 593-8324, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Miwa
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001205:Ascorbic Acid / Q000494:pharmacology*; D002286:Carcinoma, Ehrlich Tumor / Q000628:therapy*; D059447:Cell Cycle Checkpoints; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D003131:Combined Modality Therapy; D004354:Drug Screening Assays, Antitumor; D006979:Hyperthermia, Induced; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D017382:Reactive Oxygen Species; D001205:Ascorbic Acid