title: The impact of nitric oxide on calcium homeostasis in PE/CA-PJ15 cells.
abstract: OBJECTIVE
  Nitric oxide (NO) production and Ca(2+) homeostasis are key determinants for the control of many cell functions. NO is known to be a mediator of Ca(2+) homeostasis in a highly complex and cell-specific manner and although Ca(2+) homeostasis has been explored in human oral cancer cells, the exact mechanisms are not completely understood. In this study we investigated the impact of exogenous NO on [Ca(2+)]c homeostasis in PE/CA-PJ15 cells.
  
  
  METHODS
  Cells were treated with S-nitrosocysteine as NO-donor and the determinations of cytosolic Ca(2+) concentrations were performed using FURA-2 AM. Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) and oligomycin were used to challenge mitochondrial functionality, whereas thapsigargin (TG) and La(3+) were employed to perturb intracellular calcium levels.
  
  
  RESULTS
  NO derived from S-nitrosocysteine (CySNO) induced a dose-dependent reduction of cytosolic calcium [Ca(2+)]c whereas oxy-haemoglobin (oxyHb) completely counteracted this effect. Subsequently, we assessed possible relationships between NO and cellular structures responsible for Ca(2+) homeostasis. We found that uncoupling of mitochondrial respiration with carbonyl-cyanide-4-(trifluoromethoxy)-phenylhydrazone (FCCP) and oligomycin strongly reduced the effect of NO on [Ca(2+)]c. Moreover, we found that during this mitochondrial energetic deficit, the effect of NO on [Ca(2+)]c was also reduced in the presence of La(3+) or thapsigargin.
  
  
  CONCLUSIONS
  NO induces a concentration-dependent [Ca(2+)]c reduction in PE/CA-PJ15 human oral cancer cells and potentiates mitochondrial Ca(2+) buffering in the presence of TG or La(3+). Further, we show that exogenous NO deregulates Ca(2+) homeostasis in PE/CA-PJ15 cells with fully energized mitochondria.
authors.affiliation: Dipartimento di Medicina Sperimentale e Scienze Biochimiche, University of Perugia, Italy. Electronic address: carlo.palmerini@unipg.it.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tiribuzi
authors.affiliation: Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Research Unit of Biochemistry and Molecular Biology, University of Perugia, Perugia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Tartacca
authors.affiliation: Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Research Unit of Biochemistry and Molecular Biology, University of Perugia, Perugia, Italy.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Aisa
authors.affiliation: Dipartimento di Specialità Medico Chirurgiche e Sanità pubblica, University of Perugia, Perugia, Italy.
authors.forename: Giuliano Giorgio
authors.initials: GG
authors.lastname: Cerulli
authors.affiliation: Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Research Unit of Biochemistry and Molecular Biology, University of Perugia, Perugia, Italy.
authors.forename: Carlo Alberto
authors.initials: CA
authors.lastname: Palmerini
mesh_terms: D020013:Calcium Signaling / Q000187:drug effects*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D003600:Cytosol / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D016257:Fura-2 / Q000494:pharmacology; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D008928:Mitochondria; D009569:Nitric Oxide / Q000494:pharmacology*; D009840:Oligomycins / Q000494:pharmacology; D010108:Oxyhemoglobins / Q000494:pharmacology; D026403:S-Nitrosothiols / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D009840:Oligomycins; D010108:Oxyhemoglobins; D026403:S-Nitrosothiols; D009569:Nitric Oxide; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D019284:Thapsigargin; C021315:S-nitrosocysteine; D003545:Cysteine; D016257:Fura-2
keywords: Cytosolic calcium; Endoplasmic reticulum; Mitochondrion; Nitric oxide