Investigation to Determine Whether Delayed Toxicity Can be used to Predict Genotoxicity <i>in vitro</i>

Abstract

Induction of chromosome damage in mammalian cells by chemicals generally requires DNA replication and toxicity is, therefore, delayed. We, therefore, investigated whether delayed cytotoxicity can be used to predict genotoxicity. Dividing Chinese Hamster Lung (CHL) cells cultured in 96 well microtitre plates, were exposed for 3 hours to Mitomycin C (MMC), Cyclophosphamide (CPH), Methylmethane sulfonate (MMS), 2-Nitrofluorene (2-NF), Dimethyl sulfoxide (DMSO), Sodium dodecyl sulfate (SDS), 9-Aminoacridine (9-AA) or 3-Methylcholanthrene (3-MC). Cytotoxicity was assessed indirectly at intervals from 0 to 72 hours after the end of exposure, using MTT uptake and reduction. The toxicity profiles of cells treated with the known genotoxins, MMC, CPA, MMS, or 9-AA, changed as time passed, while the toxicity profiles of cells treated with the nongenotoxins, DMSO or SDS remained similar throughout. However, 2-NF and 3-MC were relatively non-toxic and any effects were too subtle for the test system to detect. These results are preliminary yet this approach
appears to be suitable for detection of substances that damage chromosomes (mutagens) and are evidently toxic.

Keywords: Chromosome damage, delayed cytotoxicity, screen for genotoxins

Discovery and Innovation Vol. 19 (4) 2007: pp. 285-290