title: Mechanism of induction of binucleated cells by multiwalled carbon nanotubes as revealed by live-cell imaging analysis.
abstract: BACKGROUND
  Asbestos-induced formation of mesothelioma has been attributed to phenotypic and morphological changes in cells caused by polyploidization and aneuploidization, and multiwalled carbon nanotubes (MWCNTs) are suspected to have similar adverse effects due to the similarity in their physical form. MWCNTs and crocidolite, a kind of asbestos, show similar genotoxicity characteristics in vitro, including induction of binucleated cells. We here focused on the mechanisms underlying polyploidization during cell division on exposure to MWCNTs and conducted confocal live-cell imaging analysis using MDA-435 human breast cancer cells in which chromosomes and centromeres were visualized using fluorescent proteins.
  
  
  RESULTS
  During anaphase, relatively short MWCNT fibers (approximately 5 μm) migrated rapidly to either of the daughter cells, whereas some long MWCNT fibers (approximately 20 μm) remained inside the contractile ring and induced the formation of binucleated cells through impairment of cytokinesis. This toxicity mechanism has also been observed with crocidolite.
  
  
  CONCLUSIONS
  Our findings indicate that the mechanism of polyploidization by MWCNTs is very similar to that observed with crocidolite.
authors.affiliation: Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501 Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Yasui
authors.affiliation: Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501 Japan.
authors.forename: Nagisa
authors.initials: N
authors.lastname: Kamoshita
authors.affiliation: Faculty of Pharmaceutical Sciences, Teikyo Heisei University, 4-21-2 Nakano, Nakano-ku, Tokyo 164-8530 Japan.
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Nishimura
authors.affiliation: Division of Genetics and Mutagenesis, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya-ku, Tokyo 158-8501 Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Honma
keywords: Crocidolite; Cytokinesis; Polyploidization