Nitrative DNA damage in cultured macrophages exposed to indium oxide

• Afroz Tahmina

  Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine

• Hiraku Yusuke

  Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine

• Ma Ning

  Faculty of Nursing, Suzuka University of Medical Science

• Ahmed Sharif

  Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine

• Oikawa Shinji

  Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine

• Kawanishi Shosuke

  Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science

• Murata Mariko

  Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine

Abstract

Objectives: Indium compounds are used in manufacturing displays of mobile phones and televisions. However, these materials cause interstitial pneumonia in exposed workers. Animal experiments demonstrated that indium compounds caused lung cancer. Chronic inflammation is considered to play a role in lung carcinogenesis and fibrosis induced by particulate matters. 8-Nitroguanine (8-nitroG) is a mutagenic DNA lesion formed during inflammation and may participate in carcinogenesis. To clarify the mechanism of carcinogenesis, we examined 8-nitroG formation in indium-exposed cultured cells. Methods: We treated RAW 264.7 mouse macrophages with indium oxide (In₂O₃) nanoparticles (primary diameter: 30-50 nm), and performed fluorescent immunocytochemistry to detect 8-nitroG. The extent of 8-nitroG formation was evaluated by quantitative image analysis. We measured the amount of nitric oxide (NO) in the culture supernatant of In₂O₃-treated cells by the Griess method. We also examined the effects of inhibitors of inducible NO synthase (iNOS) and endocytosis on In₂O₃-induced 8-nitroG formation. Results: In₂O₃ significantly increased the intensity of 8-nitroG formation in RAW 264.7 cells in a dose-dependent manner. In₂O₃-induced 8-nitroG formation was observed at 2 h and further increased at 4 h, and the amount of NO released from In₂O₃-exposed cells was significantly increased at 2-4 h compared with the control. 8-NitroG formation was suppressed by 1400W (an iNOS inhibitor), methyl-β-cyclodextrin and monodansylcadaverine (inhibitors of caveolae- and clathrin-mediated endocytosis, respectively). Conclusions: These results suggest that endocytosis and NO generation participate in indium-induced 8-nitroG formation. NO released from indium-exposed inflammatory cells may induce DNA damage in adjacent lung epithelial cells and contribute to carcinogenesis.

Journal

• Journal of Occupational Health

  Journal of Occupational Health 60 (2), 148-155, 2018

  Japan Society for Occupational Health

Keywords

• 8-Nitroguanine
• DNA damage
• Endocytosis
• Indium
• Inflammation
• Nitric oxide

Details

• CRID: 1390001204456276864
• NII Article ID: 130006565471
• NII Book ID: AA11090645
• DOI: 10.1539/joh.17-0146-oa
• ISSN: 13489585
• ISSN: 13419145
• NDL BIB ID: 028896377
• PubMed: 29187674
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I028896377
• Web Site: https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1539%2Fjoh.17-0146-OA
• Web Site: https://onlinelibrary.wiley.com/doi/pdf/10.1539/joh.17-0146-OA
• Web Site: https://search.jamas.or.jp/link/ui/2018323589
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • PubMed
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed