Gene Expression Analysis of the Hepatotoxicant Methapyrilene in Primary Rat Hepatocytes: An Interlaboratory Study Johanna M. Beekman,1 Franziska Boess,2 Heinrich Hildebrand,3 Arno Kalkuhl,4 and Laura Suter2 1Schering AG, Berlin, Germany; 2F. Hoffmann-La Roche Ltd., Basel, Switzerland; 3Bayer HealthCare AG, Wuppertal, Germany; 4Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany Abstract Genomics technologies are used in several disciplines, including toxicology. However, these technologies are relatively new, and their applications require further investigations. When investigators apply these technologies to in vitro experiments, two major issues need to be clarified: a) can in vitro toxicity studies, in combination with genomics analyses, be used to predict the toxicity of a compound ; and b) are the generated toxicogenomics data reproducible between laboratories? These questions were addressed by an interlaboratory study with laboratories of four pharmaceutical companies. We evaluated gene expression patterns from cultured rat primary hepatocytes after a 24-hr incubation with methapyrilene (MP) . Extensive data analysis showed that comparison of genomics data from different sources is complex because both experimental and statistical variability are important confounding factors. However, appropriate statistical tools allowed us to use gene expression profiles to distinguish high-dose-treated cells from vehicle-treated cells. Moreover, we correctly identified MP in an independently generated in vitro database, underlining that in vitro toxicogenomics could be a predictive tool for toxicity. From a mechanistic point of view, despite the observed site-to-site variability, there was good concordance regarding the affected biologic processes. Several subsets of regulated genes were obtained by analyzing the data sets with one method or using different statistical analysis methods. The identified genes are involved in cellular processes that are associated to the exposure of primary hepatocytes to MP. Whether they are specific for MP and are cause or consequence of the toxicity requires further investigations. Key words: hepatotoxicity, interlaboratory study, methapyrilene, microarray, rat hepatocytes, toxicogenomics. Environ Health Perspect 114: 92-99 (2006) . doi:10.1289/ehp.7915 available via http://dx.doi.org/ [Online 12 August 2005] Address correspondence to J.M. Beekman, Schering AG, Global Pharmacogenomics, Muellerstrasse 170-178, 13342 Berlin, Germany. Telephone: 49-30-468-12554. Fax: 49-30-468-11323. E-mail: johanna.beekman@schering.de We thank S. Koehl (Boehringer Ingelheim) , C. Kneilmann (Boehringer Ingelheim) , G. Wasinska-Kempka (Bayer) , G. Gehrmann (Schering) , M. Jarzombek (Schering) , N. Schaub (Hoffmann-La Roche) , and E. Durr (Hoffmann-La Roche) for performing the rat hepatocyte experiments. Our special thanks go to M. Thiel (Bayer) and S. Patkovic (Schering) for their skillful assistance with the microarray analyses. The authors declare they have no competing financial interests. Received 11 January 2005 ; accepted 11 August 2005. The full version of this article is available for free in HTML or PDF formats. |