title: H2O2 oxidative damage in cultured oral epithelial cells: the effect of short-term vitamin C exposure.
abstract: Smoking is the main etiology of oral cancer and generates oxygen free radicals in the oral cavity. Free radicals have been implicated in apoptosis and in DNA damage inducing alteration of the cell cycle. The antioxidant vitamin C (VC) is reported to inhibit damage induced by free radicals. We exposed cultures of normal human oral epithelial cells to hydrogen peroxide (H2O2) in the presence and absence of VC. Generation of hydroxyl radicals was measured by electron paramagnetic resonance (EPR), cell cycle alterations by flow cytometry, cell death by SYTO 11 and morphology by organotypic culture. Human primary cell culture was given four treatments - control, VC alone, H2O2 alone and VC followed by H2O2. Cell cycle analysis indicated cultures treated with H2O2 had fewer cells in G1 phase (26%) and higher number of cells in S phase (44%) compared to the control (G1 70% & S 14%). Cell cycle of 48 hour VC treatment followed by H2O2 was similar to H2O2 alone. SYTO 11 showed 22% cell death when treated with H2O2 alone compared to 9% of normal control. By organotypic culture H2O2 alone induced a two-fold cell proliferation, loss of maturation, nuclear hyperchromatism and nuclear crowding. Our results suggest that H2O2 is capable of altering the cell cycle and morphology of cultured normal human oral epithelial cells. Forty-eight hour exposure to Vitamin C does not prevent the cell cycle changes caused by hydroxyl radicals.
authors.affiliation: Division of Oral and Maxillofacial Surgery, School of Dentistry, University of Washington, Seattle 98195, USA. doda@u.washington.edu
authors.forename: D
authors.initials: D
authors.lastname: Oda
authors.forename: M P
authors.initials: MP
authors.lastname: Nguyen
authors.forename: G A
authors.initials: GA
authors.lastname: Royack
authors.forename: D C
authors.initials: DC
authors.lastname: Tong
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D016923:Cell Death / Q000187:drug effects; D004249:DNA Damage; D004578:Electron Spin Resonance Spectroscopy; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000633:toxicity*; D017665:Hydroxyl Radical / Q000633:toxicity; D009061:Mouth Mucosa / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress
chemical_list: D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid