Sarah AdlerDavid BasketterStuart CretonOlavi PelkonenJan van BenthemValerie Zuang • Klaus Ejner AndersenAlexandre Angers-LoustauAynur AptulaAnna Bal-PriceEmilio Benfenati • Ulrike BernauerJos BessemsFrederic Y. BoisAlan BoobisEsther BrandonSusanne Bremer • Thomas BroschardSilvia CasatiSandra CoeckeRaffaella CorviMark CroninGeorge Daston • Wolfgang DekantSusan FelterElise GrignardUrsula Gundert-RemyTuula HeinonenIan Kimber • Jos KleinjansHannu KomulainenReinhard KreilingJoachim KreysaSofia Batista LeiteGeorge Loizou • Gavin MaxwellPaolo MazzatortaSharon MunnStefan PfuhlerPascal PhrakonkhamAldert Piersma • Albrecht PothPilar PrietoGuillermo RepettoVera RogiersGreet SchoetersMichael Schwarz • Rositsa SerafimovaHanna TahtiEmanuela TestaiJoost van DelftHenk van LoverenMathieu Vinken • Andrew WorthJose ´-Manuel Zaldivar

/pdf/alternative-non-animal-methods-for-cosmetics-testing-current-u3dtxjb56j.pdf

Alternative (non-animal) methods for cosmetics testing: current status and future prospects—2010

It is well established that cancer is a multi-step process which involves initiation, promotion and progression. Chemical carcinogens can alter any of these processes to induce their carcinogenic effects. The presence of multiple mutations in critical genes is a distinctive feature of cancer cells and supports the contention that cancer arises through the accumulation of irreversible DNA damage. In the majority of instances, chemical carcinogens, directly or after xenobiotic metabolism, induce DNA damage and act in a ‘genotoxic’ manner. There is, however, a group of carcinogens that induce cancer via non-genotoxic mechanisms. Non-genotoxic carcinogens have been shown to act as tumor promoters (1,4-dichlorobenzene), endocrine-modifiers (17β-estradiol), receptor-mediators (2,3,7,8-tetrachlorodibenzo- p -dioxin), immunosuppressants (cyclosporine) or inducers of tissue-specific toxicity and inflammatory responses (metals such as arsenic and beryllium). The diversity of modes of action of non-genotoxic carcinogens, the tissue and species specificity, and the absence of genotoxicity makes predicting their carcinogenic potential extremely challenging. In order to better understand the mechanisms of known human non-genotoxic carcinogens and to illustrate the importance of a weight of evidence approach when evaluating their carcinogenic potential, we will (1) evaluate the proportion of non-genotoxic carcinogens among known, probable and possible human carcinogens classified by the International Agency for Research on Cancer (IARC), (2) estimate the risk of exposure of human non-genotoxic carcinogens through margin of exposure (MOE) evaluation, and (3) discuss potential alternative methods for their detection. Our analysis demonstrated that human non-genotoxic carcinogens were present in 12% (45/371) of IARC's Groups 1, 2A and 2B carcinogens and that a potential hazard was associated with 27% (12/45) of them. Consequently, it is suggested that for all genotoxic chemicals, the mode of action is investigated for hazard and risk evaluation. Further, if negative genotoxic compounds have putative non-genotoxic modes of action, appropriate risk measures should be implemented.

Mechanisms of non-genotoxic carcinogens and importance of a weight of evidence approach.

Systemic toxicity testing forms the cornerstone for the safety evaluation of substances. Pressures to move from traditional animal models to novel technologies arise from various concerns, including: the need to evaluate large numbers of previously untested chemicals and new products (such as nanoparticles or cell therapies), the limited predictivity of traditional tests for human health effects, duration and costs of current approaches, and animal welfare considerations. The latter holds especially true in the context of the scheduled 2013 marketing ban on cosmetic ingredients tested for systemic toxicity. Based on a major analysis of the status of alternative methods (Adler et al., 2011) and its independent review (Hartung et al., 2011), the present report proposes a roadmap for how to overcome the acknowledged scientific gaps for the full replacement of systemic toxicity testing using animals. Five whitepapers were commissioned addressing toxicokinetics, skin sensitization, repeated-dose toxicity, carcinogenicity, and reproductive toxicity testing. An expert workshop of 35 participants from Europe and the US discussed and refined these whitepapers, which were subsequently compiled to form the present report. By prioritizing the many options to move the field forward, the expert group hopes to advance regulatory science.

/pdf/a-roadmap-for-the-development-of-alternative-non-animal-35m1hr1jow.pdf

A roadmap for the development of alternative (non-animal) methods for systemic toxicity testing.

Hydrogen sulfide (H(2)S), a metabolic end product of sulfate-reducing bacteria, represents a genotoxic insult to the colonic epithelium, which may also be linked with chronic disorders such as ulcerative colitis and colorectal cancer. This study defined the early (30 min) and late (4 hr) response of nontransformed human intestinal epithelial cells (FHs 74 Int) to H(2)S. The genotoxicity of H(2)S was measured using the single-cell gel electrophoresis (comet) assay. Changes in gene expression were analyzed after exposure to a genotoxic, but not cytotoxic, concentration of H(2)S (500 muM H(2)S) using pathway-specific quantitative RT-PCR gene arrays. H(2)S was genotoxic in a concentration range from 250 to 2,000 microM, which is similar to concentrations found in the large intestine. Significant changes in gene expression were predominantly observed at 4 hr, with the greatest responses by PTGS2 (COX-2; 7.92-fold upregulated) and WNT2 (7.08-fold downregulated). COX-2 was the only gene upregulated at both 30 min and 4 hr. Overall, the study demonstrates that H(2)S modulates the expression of genes involved in cell-cycle progression and triggers both inflammatory and DNA repair responses. This study confirms the genotoxic properties of H(2)S in nontransformed human intestinal epithelial cells and identifies functional pathways by which this bacterial metabolite may perturb cellular homeostasis and contribute to the onset of chronic intestinal disorders.

DNA damage and toxicogenomic analyses of hydrogen sulfide in human intestinal epithelial FHs 74 Int cells

https://www.dora.lib4ri.ch/eawag/islandora/object/eawag%3A9131/datastream/PDF/Groh-2015-Development_and_application_of_the-%28published_version%29.pdf

Development and application of the adverse outcome pathway framework for understanding and predicting chronic toxicity: I. Challenges and research needs in ecotoxicology.

Development and evaluation of a genomic signature for the prediction and mechanistic assessment of nongenotoxic hepatocarcinogens in the rat.

Characterization and interlaboratory comparison of a gene expression signature for differentiating genotoxic mechanisms.

The multi-lab International Life Sciences Institute (ILSI) project on the application of genomics to risk assessment offered the unique opportunity to investigate the influence of variability within and between laboratories on identifying biologically relevant gene expression changes. We assessed the gene expression profiles of mouse lymphoma L5178Y cells treated with hydroxyurea (HU) in three independent studies from two different laboratories, sanofi aventis and Procter & Gamble. Cells were dosed for 4 hr and harvested immediately at the end of the treatment or after a 20-hr recovery period. Cytotoxicity and genotoxicity were evaluated by standard assays. Statistical analysis of these data revealed that, while gene expression responses to HU treatment were markedly different at 4 hr vs. 24 hr, there was otherwise a consistent pattern of dose–response across the three studies. Therefore, the studies were merged and each time point was evaluated separately. At 4 hr, we identified 173 (P < 0.0001) dose-responsive genes with a common trend in all three studies. These were mainly associated with the cell cycle, DNA repair and DNA metabolism, and in particular, the intra-S and G2/M phase checkpoints. At 24 hr, we identified 434 dose-responsive genes common across studies. These genes were involved in lymphocyte-specific activities and the activation of apoptosis via the caspase cascade. Our results show that despite inter-laboratory variability, combining the three studies in a single statistical analysis identifies more significantly-modulated genes than in any of the individual studies, due to improved statistical sensitivity. The genes identified in our study provide information that is relevant to HU biology. Environ. Mol. Mutagen., 2005. © 2005 Wiley-Liss, Inc.

Laboratory variability does not preclude identification of biological functions impacted by hydroxyurea.

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Development and evaluation of a genomic signature for the prediction and mechanistic assessment of nongenotoxic hepatocarcinogens in the rat.

Characterization and interlaboratory comparison of a gene expression signature for differentiating genotoxic mechanisms.

Laboratory variability does not preclude identification of biological functions impacted by hydroxyurea.