title: Potentiality of syringetin for preferential radiosensitization to cancer cells.
abstract: To examine the enhancing effects of syringetin on the radiosensitivity of normal and cancer cells, and the related mechanism.
  
  
  
  We used normal human lung and mouse fibroblasts as well as human lung and mouse cancer cells derived from the above normal fibroblasts. Cell radiosensitivity was measured using a colony formation assay. Apoptosis was analyzed with DAPI staining and Western blots. DNA lesions were analyzed with γH2AX immunofluorescent staining.
  
  
  
  The colony formation assay showed that syringetin enhanced radiosensitivity more effectively in cancer cells (H1299 and C3H/MCA clone 15) compared with normal cells (HFL-III and C3H/10T1/2). The radiosensitizing effect of syringetin was observed in mutated p53 and wild-type p53-transfected H1299 cells regardless of p53 status. Apoptosis was more frequently observed in X-ray-irradiated H1299 cells combined with syringetin compared with X-ray-only-treated cells. Enhanced apoptosis by syringetin was not observed in HFL-III cells. Western blot analysis showed that X-ray-induced Caspase-3 activation was enhanced by syringetin in H1299 cells. The number of X-ray-induced DNA double-strand breaks (DSB) measured by quantitative analysis of γH2AX foci was the same for H1299 cells treated with X-rays with or without syringetin.
  
  
  
  This study supports the hypothesis that syringetin enhances radiosensitivity more effectively in cancer cells than in normal cells through enhancement of the Caspase-3-mediated apoptosis pathway. Syringetin could be useful in the development of novel efficacious radiosensitizers.
authors.affiliation: a Department of Biology , Center for Humanities and Sciences, Ibaraki Prefectural University of Health Sciences , Ibaraki , Japan.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Bando
authors.affiliation: b Department of Community Health and Epidemiology , Nara Medical University School of Medicine , Kashihara , Nara , Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Hatano
authors.affiliation: c Laboratory of Cell Signaling and Metabolic Disease , National Institutes of Biomedical Innovation , Ibaragi , Osaka , Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takemori
authors.affiliation: d Department of Radiological Sciences , Ibaraki Prefectural University of Health Sciences , Ibaraki , Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kubota
authors.affiliation: a Department of Biology , Center for Humanities and Sciences, Ibaraki Prefectural University of Health Sciences , Ibaraki , Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Ohnishi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005240:Feasibility Studies; D005419:Flavonoids / Q000008:administration & dosage*; D051379:Mice; D009374:Neoplasms, Experimental / Q000235:genetics / Q000473:pathology* / Q000532:radiotherapy*; D011836:Radiation Tolerance / Q000187:drug effects*; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage*; D011879:Radiotherapy Dosage
chemical_list: D005419:Flavonoids; D011838:Radiation-Sensitizing Agents; C546494:syringetin
keywords: Flavonoid; phytochemical; radiosensitizer; syringetin