Although the value of the regulatory accepted batteries for in vitro genotoxicity testing is recognized, they result in a high
number of false positives. This has a major impact on society and industries developing novel compounds for pharmaceutical,
chemical, and consumer products, as afflicted compounds have to be (prematurely) abandoned or further tested on
animals. Using the metabolically competent human HepaRG
™ cell line and toxicogenomics approaches, we have developed
an upgraded, innovative, and proprietary gene classifier. This gene classifier is based on transcriptomic changes induced by
12 genotoxic and 12 non-genotoxic reference compounds tested at sub-cytotoxic concentrations, i.e., IC10 concentrations
as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The resulting gene classifier
was translated into an easy-to-handle qPCR array that, as shown by pathway analysis, covers several different cellular
processes related to genotoxicity. To further assess the predictivity of the tool, a set of 5 known positive and 5 known negative
test compounds for genotoxicity was evaluated. In addition, 2 compounds with debatable genotoxicity data were tested
to explore how the qPCR array would classify these. With an accuracy of 100%, when equivocal results were considered
positive, the results showed that combining HepaRG
™ cells with a genotoxin-specific qPCR array can improve (geno)toxicological
hazard assessment. In addition, the developed qPCR array was able to provide additional information on compounds
for which so far debatable genotoxicity data are available. The results indicate that the new in vitro tool can improve human
safety assessment of chemicals in general by basing predictions on mechanistic toxicogenomics information.
