title: In vitro cytotoxicity of zoledronate (nitrogen-containing bisphosphonate: NBP) and/or etidronate (non-NBP) in tumour cells and periodontal cells.
abstract: OBJECTIVE
  Nitrogen-containing bisphosphonates (NBPs), the first-choice drugs for diseases that cause enhanced bone resorption, may injure jawbones and gastrointestinal tissues. In rodents, NBPs cause necrosis at injection sites. Bisphosphonates accumulate within bones, especially where there is inflammation. We hypothesized that if jawbone-accumulated NBPs are released, they may directly injure cells around the jawbones. To examine this hypothesis, we compared the direct effects of zoledronate (NBP) and/or etidronate (non-NBP) on various cells, including periodontal cells.
  
  
  METHODS
  Various human tumour cells (such as squamous carcinoma cells and prostate adenocarcinoma cells) and periodontal cells (such as gingival fibroblasts and periodontal ligament cells) were incubated with or without zoledronate and/or etidronate. Cell viability and cytotoxicity were determined by tetrazolium dye assay and by FITC-Annexin V/propidium iodide assay, respectively.
  
  
  RESULTS
  Zoledronate, at 100μM, was toxic to all types of cells tested, while its toxicity varied among cells at both 1 and 10μM. There was no clear difference between tumour cells and non-tumour cells in sensitivity to the cytotoxicity of zoledronate. In contrast, etidronate was not toxic at 1-100μM in any of the cells tested. Interestingly, etidronate reduced the cytotoxicity of zoledronate in many cell-types, including gingival fibroblasts.
  
  
  CONCLUSIONS
  These results, together with those reported by others and those from our previous in vivo experiments, suggest that NBPs, upon release from jawbones (e.g., during dental surgery or bone infection), may directly injure various cells located around the jawbones, and that etidronate may be protective against the cytotoxicity of NBPs in periodontal tissues.
authors.affiliation: Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, 4-1 Seiryo-machi, Sendai 980-8575, Japan. yukinori-tanaka@dent.tohoku.ac.jp
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nagai
authors.forename: Mina
authors.initials: M
authors.lastname: Dohdoh
authors.forename: Takefumi
authors.initials: T
authors.lastname: Oizumi
authors.forename: Akiko
authors.initials: A
authors.lastname: Ohki
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Kuroishi
authors.forename: Shunji
authors.initials: S
authors.lastname: Sugawara
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Endo
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology; D017304:Annexin A5; D017209:Apoptosis / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000633:toxicity*; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004396:Coloring Agents; D003739:Dental Cementum / Q000187:drug effects; D004164:Diphosphonates / Q000037:antagonists & inhibitors / Q000633:toxicity*; D042783:Endothelial Cells / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D012968:Etidronic Acid / Q000494:pharmacology / Q000633:toxicity*; D005347:Fibroblasts / Q000187:drug effects; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D005456:Fluorescent Dyes; D005881:Gingiva / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000037:antagonists & inhibitors / Q000633:toxicity*; D007948:Leukemia, Monocytic, Acute / Q000473:pathology; D059630:Mesenchymal Stem Cells / Q000187:drug effects; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects; D011419:Propidium; D013778:Tetrazolium Salts; D014471:Umbilical Veins / Q000166:cytology; D000077211:Zoledronic Acid
chemical_list: C476329:2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H tetrazolium monosodium salt; D017304:Annexin A5; D050071:Bone Density Conservation Agents; D004396:Coloring Agents; D004164:Diphosphonates; C492760:FITC-annexin A5; D005456:Fluorescent Dyes; D007093:Imidazoles; D013778:Tetrazolium Salts; D011419:Propidium; D000077211:Zoledronic Acid; D016650:Fluorescein-5-isothiocyanate; D012968:Etidronic Acid