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Single-walled carbon nanotube-induced mitotic disruption.

Authors
Sargent-L; Hubbs-AF; Young-S-H; Kashon-ML; Dinu-CZ; Salisbury-JL; Benkovic-SA; Lowry-DT; Murray-AR; Kisin-ER; Siegrist-KJ; Battelli-L; Mastovich-J; Sturgeon-JL; Bunker-KL; Shvedova-AA; Reynolds-SH
Source
Mutat Res Genet Toxicol Environ Mutagen 2012 Jun; 745(1-2):28-37
NIOSHTIC No.
20040054
Abstract
Carbon nanotubes were among the earliest products of nanotechnology and have many potential applications in medicine, electronics, and manufacturing. The low density, small size, and biological persistence of carbon nanotubes create challenges for exposure control and monitoring and make respiratory exposures to workers likely. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to 24, 48 and 96 g/cm2 single-walled carbon nanotubes (SWCNT). To investigate mitotic spindle aberrations at concentrations anticipated in exposed workers, primary and immortalized human airway epithelial cells were exposed to SWCNT for 24-72 h at doses equivalent to 20 weeks of exposure at the Permissible Exposure Limit for particulates not otherwise regulated. We have now demonstrated fragmented centrosomes, disrupted mitotic spindles and aneuploid chromosome number at those doses. The data further demonstrated multipolar mitotic spindles comprised 95 percent of the disrupted mitoses. The increased multipolar mitotic spindles were associated with an increased number of cells in the G2 phase of mitosis, indicating a mitotic checkpoint response. Nanotubes were observed in association with mitotic spindle microtubules, the centrosomes and condensed chromatin in cells exposed to 0.024, 0.24, 2.4 and 24 g/cm2 SWCNT. Three-dimensional reconstructions showed carbon nanotubes within the centrosome structure. The lower doses did not cause cytotoxicity or reduction in colony formation after 24 h; however, after three days, significant cytotoxicity was observed in the SWCNT-exposed cells. Colony formation assays showed an increased proliferation seven days after exposure. Our results show significant disruption of the mitotic spindle by SWCNT at occupationally relevant doses. The increased proliferation that was observed in carbon nanotube-exposed cells indicates a greater potential to pass the genetic damage to daughter cells. Disruption of the centrosome is common in many solid tumors including lung cancer. The resulting aneuploidy is an early event in the progression of many cancers, suggesting that it may play a role in both tumorigenesis and tumor progression. These results suggest caution should be used in the handling and processing of carbon nanotubes.
Keywords
Nanotechnology; Lung-cells; Lung-fibrosis; Gene-mutation; Genotoxicity; Dose-response; Exposure-assessment; Exposure-levels; Cell-function; Cellular-reactions; Chromosome-damage; Chromosome-disorders; Mitosis; Cytotoxic-effects; Author Keywords: Genotoxic effects; Cell division; Cellular uptake; Lung cancer; Lung cells
Contact
L. M. Sargent, Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Mailstop L-3014, Morgantown, WV 26505, USA
CODEN
MRGMFI
CAS No.
7440-44-0
Publication Date
20120614
Document Type
Journal Article
Fiscal Year
2012
NTIS Accession No.
NTIS Price
Identifying No.
B12212011
Issue of Publication
1-2
ISSN
1383-5718
NIOSH Division
HELD
Priority Area
Manufacturing
Source Name
Mutation Research - Genetic Toxicology and Environmental Mutagenesis
State
WV; MN; TN; PA
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