title: O2 and Ca(2+) fluxes as indicators of apoptosis induced by rose bengal-mediated photodynamic therapy in human oral squamous carcinoma cells.
abstract: OBJECTIVE
  Photodynamic therapy (PDT) triggers various cellular responses and induces cell death via necrosis and/or apoptosis. This study evaluated the feasibility of using O2 and Ca(2+) fluxes as indicators of apoptosis induced by rose bengal (RB)-mediated PDT in human oral squamous carcinoma cells (Cal27 cells).
  
  
  METHODS
  Intracellular reactive oxygen species (ROS) generation was assessed by the dichloro-dihydro-fluorescein diacetate (DCFH-DA) method. Real-time O2 and Ca(2+) flux measurements were performed using the noninvasive micro-test technique (NMT). Apoptosis of the PDT-treated cells was confirmed by 4'6-diamidino-2-phenylindole-dilactate staining. The activation of apoptosis-related molecules was examined using Western blot. We assayed the effects of the fluctuation of O2 and Ca(2+) flux in response to PDT and the apoptotic mechanism, by which ROS, O2, and Ca(2+) synergistically may trigger apoptosis in PDT-treated cells.
  
  
  RESULTS
  Real-time O2 and Ca(2+) flux measurements revealed that these indicators were involved in the timely regulation of apoptosis in the PDT-treated cells and were activated 2 h after PDT treatment. RB-mediated PDT significantly elicited the generation of ROS by approximately threefold, which was critical for PDT-induced apoptosis. Cytochrome c and cleaved caspase-3, caspase-9 and poly ADP ribose polymerase (PARP) were overexpressed, and the data provided evidence that 2 h was considered to be the key observation time in RB-mediated PDT-induced apoptosis in Cal27 cells.
  
  
  CONCLUSIONS
  Our collective results indicated that the effects of O2 and Ca(2+) fluxes may act as a real-time biomonitoring system of apoptosis in the RB-PDT-treated cells. Also, RB-mediated PDT can be a potential and effective therapeutic modality in oral squamous cell carcinoma.
authors.affiliation: 1 Department of Periodontics, School and Hospital of Stomatology, Wuhan University , Wuhan, China .
authors.forename: Li
authors.initials: L
authors.lastname: Song
authors.forename: Chengzhang
authors.initials: C
authors.lastname: Li
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zou
authors.forename: Fang
authors.initials: F
authors.lastname: Dai
authors.forename: Xueqing
authors.initials: X
authors.lastname: Luo
authors.forename: Beike
authors.initials: B
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Ni
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
mesh_terms: D017209:Apoptosis / Q000528:radiation effects*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D005456:Fluorescent Dyes / Q000494:pharmacology*; D006801:Humans; D009062:Mouth Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012395:Rose Bengal / Q000494:pharmacology*
chemical_list: D005456:Fluorescent Dyes; D017382:Reactive Oxygen Species; D012395:Rose Bengal