title: NEIL2 protects against oxidative DNA damage induced by sidestream smoke in human cells.
abstract: Secondhand smoke (SHS) is a confirmed lung carcinogen that introduces thousands of toxic chemicals into the lungs. SHS contains chemicals that have been implicated in causing oxidative DNA damage in the airway epithelium. Although DNA repair is considered a key defensive mechanism against various environmental attacks, such as cigarette smoking, the associations of individual repair enzymes with susceptibility to lung cancer are largely unknown. This study investigated the role of NEIL2, a DNA glycosylase excising oxidative base lesions, in human lung cells treated with sidestream smoke (SSS), the main component of SHS. To do so, we generated NEIL2 knockdown cells using siRNA-technology and exposed them to SSS-laden medium. Representative SSS chemical compounds in the medium were analyzed by mass spectrometry. An increased production of reactive oxygen species (ROS) in SSS-exposed cells was detected through the fluorescent detection and the induction of HIF-1α. The long amplicon-quantitative PCR (LA-QPCR) assay detected significant dose-dependent increases of oxidative DNA damage in the HPRT gene of cultured human pulmonary fibroblasts (hPF) and BEAS-2B epithelial cells exposed to SSS for 24 h. These data suggest that SSS exposure increased oxidative stress, which could contribute to SSS-mediated toxicity. siRNA knockdown of NEIL2 in hPF and HEK 293 cells exposed to SSS for 24 h resulted in significantly more oxidative DNA damage in HPRT and POLB than in cells with control siRNA. Taken together, our data strongly suggest that decreased repair of oxidative DNA base lesions due to an impaired NEIL2 expression in non-smokers exposed to SSS would lead to accumulation of mutations in genomic DNA of lung cells over time, thus contributing to the onset of SSS-induced lung cancer.
authors.affiliation: Department of Cancer & DNA Damage Responses, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Altaf H
authors.initials: AH
authors.lastname: Sarker
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America.
authors.forename: Arpita
authors.initials: A
authors.lastname: Chatterjee
authors.affiliation: Department of Cell Biology & Neuroscience, University of California Riverside, Riverside, California, United States of America.
authors.forename: Monique
authors.initials: M
authors.lastname: Williams
authors.affiliation: Department of Cell Biology & Neuroscience, University of California Riverside, Riverside, California, United States of America.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Lin
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco General Hospital Medical Center, San Francisco, California, United States of America.
authors.forename: Christopher
authors.initials: C
authors.lastname: Havel
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco General Hospital Medical Center, San Francisco, California, United States of America.
authors.forename: Peyton
authors.initials: P
authors.lastname: Jacob
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America.
authors.forename: Istvan
authors.initials: I
authors.lastname: Boldogh
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America.
authors.forename: Tapas K
authors.initials: TK
authors.lastname: Hazra
authors.affiliation: Department of Cell Biology & Neuroscience, University of California Riverside, Riverside, California, United States of America.
authors.forename: Prudence
authors.initials: P
authors.lastname: Talbot
authors.affiliation: Department of Cancer & DNA Damage Responses, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Bo
authors.initials: B
authors.lastname: Hang
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D003470:Culture Media; D004249:DNA Damage; D045647:DNA Glycosylases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism; D018384:Oxidative Stress; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism; D012906:Smoke / Q000009:adverse effects*
chemical_list: D003470:Culture Media; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D012906:Smoke; D007041:Hypoxanthine Phosphoribosyltransferase; D045647:DNA Glycosylases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; C473642:NEIL2 protein, human