title: Selective cytotoxic effects of low-power laser irradiation on human oral cancer cells.
abstract: OBJECTIVE
  Low-power laser irradiation (LPLI) is known to regulate cell proliferation and migration in clinical use. Recent studies have shown that LPLI induces cell death in some certain types of cancer cell lines. However, the cytotoxic selectivity of LPLI for cancer cells is not fully understood. The aim of this study was to compare the cytotoxic effects of LPLI in both human oral cancer OC2 cells and normal human gingival fibroblast (HGF) cells.
  
  
  METHODS
  LPLI at 810 nm with an energy density from 10 to 60 J/cm(2) was used to irradiate human oral cancer OC2 cells and normal HGF cells.
  
  
  RESULTS
  We found that LPLI significantly diminished cell viability of human oral cancer OC2 cells due to cell cycle arrest at the G1 phase and the induction of cell death but that it had no or little effects on cell cycle progression and death in normal HGF cells. Moreover, the production of reactive oxygen species (ROS) and the loss of mitochondrial membrane potential (MMP) were elevated in human oral cancer OC2 cells compared with the un-irradiated cells. In contrast, these effects remained unchanged in normal HGF cells after exposure to LPLI. LPLI also induced apoptosis in caspase-3 dependent manner in human oral cancer OC2 cells, a mode of action that could be mediated by ROS and mitochondrial damage.
  
  
  CONCLUSIONS
  Our findings imply LPLI might be a potential therapy for oral cancers.
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, 813, Taiwan.
authors.forename: Wei-Zhe
authors.initials: WZ
authors.lastname: Liang
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, 813, Taiwan.|Department of Biotechnology, Fooyin University, Kaohsiung, 831, Taiwan.
authors.forename: Pei-Feng
authors.initials: PF
authors.lastname: Liu
authors.affiliation: Department of Periodontology, School of Dentistry, National Defense Medical Center and Tri-Service General Hospital, Taipei, 114, Taiwan.
authors.forename: Earl
authors.initials: E
authors.lastname: Fu
authors.affiliation: Department of Stomatology, Kaohsiung Veteran General Hospital, Kaohsiung, 813, Taiwan.
authors.forename: Hao-Sheng
authors.initials: HS
authors.lastname: Chung
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, 813, Taiwan.
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, 813, Taiwan.
authors.forename: Chih-Hsuan
authors.initials: CH
authors.lastname: Wu
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, 813, Taiwan.
authors.forename: Chih-Wen
authors.initials: CW
authors.lastname: Shu
authors.affiliation: Department of Periodontology, School of Dentistry, National Defense Medical Center and Tri-Service General Hospital, Taipei, 114, Taiwan.|Department of Stomatology, Kaohsiung Veteran General Hospital, Kaohsiung, 813, Taiwan.|Department of Dentistry, Kaohsiung Veterans General Hospital, Pingtung, 912, Taiwan.
authors.forename: Yao-Dung
authors.initials: YD
authors.lastname: Hsieh
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D005347:Fibroblasts / Q000528:radiation effects; D005881:Gingiva / Q000528:radiation effects; D006801:Humans; D028022:Low-Level Light Therapy; D009062:Mouth Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D014407:Tumor Cells, Cultured
keywords: apoptosis; low-power laser irradiation; mitochondria membrane potential; oral cancer; reactive oxygen species