title: Effect of thymol on Ca2+ homeostasis and viability in MG63 human osteosarcoma cells.
abstract: OBJECTIVE
  The effect of the natural product thymol on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and viability in MG63 human osteosarcoma cells was examined.
  
  
  METHODS
  The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)](i).
  
  
  RESULTS
  Thymol at concentrations of 200-1,000 μmol/l induced a [Ca(2+)](i) rise in a concentration-dependent fashion. The response was decreased partially by removal of extracellular Ca(2+). Thymol-induced Ca(2+) entry was inhibited by nifedipine, econazole, SK&F96365 and protein kinase C modulators. When extracellular Ca(2+) was removed, incubation with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) inhibited the thymol-induced [Ca(2+)](i) rise. Incubation with thymol also inhibited the thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C with U73122 abolished the thymol-induced [Ca(2+)](i) rise. At concentrations of 100-600 μmol/l, thymol killed cells in a concentration-dependent manner. This cytotoxic effect was not changed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid/AM. Annexin V/propidium iodide staining data suggest that thymol (200 and 400 μmol/l) induced apoptosis in a concentration-dependent manner. Thymol (200 and 400 μmol/l) also increased levels of reactive oxygen species.
  
  
  CONCLUSIONS
  In MG63 cells, thymol induced a [Ca(2+)](i) rise by inducing phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via protein kinase C-sensitive store-operated Ca(2+) channels. Thymol induced cell death that may involve apoptosis via mitochondrial pathways.
authors: Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, ROC.
authors: Hong-Tai
authors: HT
authors: Chang
authors: Shu-Shong
authors: SS
authors: Hsu
authors: Chiang-Ting
authors: CT
authors: Chou
authors: Jin-Shiung
authors: JS
authors: Cheng
authors: Jue-Long
authors: JL
authors: Wang
authors: Ko-Long
authors: KL
authors: Lin
authors: Yi-Chien
authors: YC
authors: Fang
authors: Wei-Chuan
authors: WC
authors: Chen
authors: Jau-Min
authors: JM
authors: Chien
authors: Ti
authors: T
authors: Lu
authors: Chih-Chuan
authors: CC
authors: Pan
authors: He-Hsiung
authors: HH
authors: Cheng
authors: Jong-Khing
authors: JK
authors: Huang
authors: Chun-Chi
authors: CC
authors: Kuo
authors: Kuo-Liang
authors: KL
authors: Chai
authors: Chung-Ren
authors: CR
authors: Jan
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D001859:Bone Neoplasms; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D012516:Osteosarcoma; D013943:Thymol / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D002121:Calcium Channel Blockers; D013943:Thymol; D006861:Hydrogen Peroxide; D010738:Type C Phospholipases; D002118:Calcium