title: High oxygen partial pressure increases photodynamic effect on HeLa cell lines in the presence of chloraluminium phthalocyanine.
abstract: BACKGROUND
  Photodynamic therapy (PDT) is linked with oxidative damage of biomolecules causing significant impairment of essential cellular functions that lead to cell death. It is the reason why photodynamic therapy has found application in treatment of different oncological, cardiovascular, skin and eye diseases. Efficacy of PDT depends on combined action of three components; sensitizer, light and oxygen. In the present study, we examined whether higher partial pressure of oxygen increases lethality in HeLa cell lines exposed to light in the presence of chloraluminium phthalocyanine disulfonate (ClAlPcS2).
  
  
  METHODS
  ClAlPcS2- sensitized HeLa cells incubated under different oxygen conditions were exposed to PDT. Production of singlet oxygen ((1)O2) and other forms of reactive oxygen species (ROS) as well as changes in mitochondrial membrane potential were determined by appropriately sensitive fluorescence probes. The effect of PDT on HeLa cell viability under different oxygen conditions was quantified using the standard methylthiazol tetrazolium (MTT) test.
  
  
  RESULTS
  At the highest oxygen concentration of 28 ± 2 mg/l HeLa cells were significantly more sensitive to light-activated ClAlPcS2 (EC50=0.29 ± 0.05 μM) in comparison to cells incubated at lower oxygen concentrations of 8 ± 0.5 and 0.5 ± 0.1 mg/l, where the half maximal effective concentration was 0.42 ± 0.06 μM and 0.94 ± 0.14 μM, respectively. Moreover, we found that the higher presence of oxygen is accompanied with higher production of singlet oxygen, a higher rate of type II photodynamic reactions, and a significant drop in the mitochondrial membrane potential.
  
  
  CONCLUSIONS
  These results demonstrate that the photodynamic effect in cervical cancer cells utilizing ClAlPcS2 significantly depends on oxygen level.
authors: Department of Medical Biophysics, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic bajgar@tunw.upol.cz.
authors: Robert
authors: R
authors: Bajgar
authors: Department of Medical Biophysics, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic.
authors: Hana
authors: H
authors: Kolarova
authors: Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic Institute of Biophysics, Faculty of Medicine in Pilsen, Charles University in Prague, Plzen, Czech Republic.
authors: Lukas
authors: L
authors: Bolek
authors: Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic.
authors: Svatopluk
authors: S
authors: Binder
authors: Department of Medical Biophysics, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic.
authors: Klara
authors: K
authors: Pizova
authors: Department of Medical Biophysics, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University in Olomouc, Olomouc, Czech Republic.
authors: Adela
authors: A
authors: Hanakova
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D054833:Isoindoles; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D010100:Oxygen / Q000032:analysis / Q000494:pharmacology*; D010313:Partial Pressure; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D007211:Indoles; D054833:Isoindoles; D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species; D010100:Oxygen; C013647:phthalocyanine
keywords: Photodynamic therapy; hyperoxia; reactive oxygen species