title: DNA damage and apoptosis induced by Pteridium aquilinum aqueous extract in the oral cell lines HSG and OSCC-3.
abstract: BACKGROUND
  Bracken fern (Pteridium aquilinum) has been consumed by humans and animals for centuries. However, its consumption is associated with a high incidence of cancer in the upper digestory tract of different species. Although the oral cavity is the first site of contact with ingested toxic substances, the interaction of bracken fern composites with oral cell lines has not yet been studied.
  
  
  METHODS
  In order to study the biological responses of oral cells exposed to bracken fern, we evaluated the genotoxic and cytotoxic effects of a bracken fern aqueous extract in oral cell lines. Human submandibular gland (HSG) and human oral epithelium cells (OSCC-3) cells were treated with three different concentrations of the extract. DNA damage was determined by the comet assay, and cellular morphology was examined by light microscopy. Apoptotic changes were evaluated by transmission electron microscopy and TUNEL assay.
  
  
  RESULTS
  The comet assay revealed that the extract was genotoxic for both cell lines but the results were not dose-dependent. The morphological and ultrastructural analyses showed that the extract caused conspicuous alterations in both cell types: uncommon chromatin condensation, nuclear picnosis, cellular volume decrease, nuclear envelope disruption, formation of numerous vacuoles of different sizes and apoptotic bodies. The TUNEL assay confirmed apoptosis induction.
  
  
  CONCLUSIONS
  These results demonstrate that the extract was cytotoxic to HSG and OSCC-3 cells, and that cellular degeneration occurred mainly by apoptosis. We believe that oral cells could trigger apoptosis after bracken fern induced DNA damage, in order to avoid the malignant transformation.
authors.affiliation: Department of Cellular Biology, Institute of Biological Sciences, University of Brasília, Brasília, Brazil.
authors.forename: Luciana Oliveira
authors.initials: LO
authors.lastname: Pereira
authors.forename: Leandro Santos
authors.initials: LS
authors.lastname: Bicalho
authors.forename: Mariana
authors.initials: M
authors.lastname: Campos-da-Paz Lopes
authors.forename: Thiago Machado Mello
authors.initials: TM
authors.lastname: de Sousa
authors.forename: Sônia Nair
authors.initials: SN
authors.lastname: Báo
authors.forename: Maria
authors.initials: M
authors.lastname: de Fátima Menezes Almeida Santos
authors.forename: Marcio José Poças
authors.initials: MJ
authors.lastname: Fonseca
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D015197:Carcinogenicity Tests; D002274:Carcinogens, Environmental / Q000633:toxicity*; D002460:Cell Line; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects*; D006801:Humans; D009061:Mouth Mucosa / Q000166:cytology; D010936:Plant Extracts / Q000633:toxicity; D032498:Pteridium / Q000633:toxicity*; D013363:Submandibular Gland / Q000166:cytology / Q000187:drug effects*; D014407:Tumor Cells, Cultured
chemical_list: D002274:Carcinogens, Environmental; D010936:Plant Extracts