DNA damaging properties of single walled carbon nanotubes in human colon carcinoma cells

Abstract

Single walled carbon nanotubes were studied with respect to cytotoxic and genotoxic properties in cells of the gastrointestinal tract as exemplified for the human colon carcinoma cell line HT29. No effect on cell growth in the sulphorhodamine B assay was observed after 24 h of incubation, whereas growth inhibitory properties were found after 48 and 72 h. After 24 h incubation a decrease of mitochondrial activity (WST-1) was measured (≥0.1 μg/ml), whereas membrane integrity (lactate dehydrogenase) was not affected. In cytotoxic concentrations, the formation of reactive oxygen species and a slight increase of total glutathione and nuclear Nrf2 were observed. However, already in subcytotoxic concentrations substantial DNA damaging effects were found in the alkaline comet assay, which were not associated with enhanced formation of formamidopyrimidine-DNA-glycosylase-sensitive sites. In addition, an increase of kinetochore-negative micronuclei (V79) and phosphorylation of the tumour suppressor protein p53 (HT29) underlined the genotoxic potential of these nanostructures.

Keywords::

• DNA integrity
• comet assay
• oxidative stress
• micronuclei
• glutathione

Acknowledgements

This work was partly funded by the DFG (Center for Functional Nanostructures (CFN), E1.1 and C3.2). The authors also gratefully acknowledge support by the Helmholtz Association under POF NanoMikro and Anna Bytzek and Norbert Kandler (University of Vienna, Institute of Inorganic Chemistry) for their help in collecting the ICP-MS data.