The idiosyncratic drug-induced gene expression changes in HepG2 cells.

The inflammatory stress has been associated with an increase in susceptibility to idiosyncratic drug-induced liver injury (DILI). However, the molecular mechanisms of this inflammation-associated idiosyncratic drug hepatotoxicity remain unknown. We exposed HepG2 cells with high and low doses of three idiosyncratic (I) and three non-idiosyncratic (N) compounds, in the presence (I+ and N+) or absence (I- and N-) of a cytokine mix for 6, 12 and 24 h.

Omics-based identification of the combined effects of idiosyncratic drugs and inflammatory cytokines on the development of drug-induced liver injury.

The mechanisms of idiosyncratic drug-induced hepatotoxicity remain largely unclear. It has demonstrated that the drug idiosyncrasy is potentiated in the context of inflammation and intracellular ceramides may play a role in this process. To study the mechanisms, HepG2 cells were co-treated with high and low doses of three idiosyncratic (I) and three non-idiosyncratic (N) compounds, with (I+ and N+) or without (I- and N-) a cytokine mix.

Bayesian Network Inference Enables Unbiased Phenotypic Anchoring of Transcriptomic Responses to Cigarette Smoke in Humans.

Microarray-based transcriptomic analysis has been demonstrated to hold the opportunity to study the effects of human exposure to, e.g., chemical carcinogens at the whole genome level, thus yielding broad-ranging molecular information on possible carcinogenic effects.

Learning to (dis)like: The effect of evaluative conditioning with tastes and faces on odor valence assessed by implicit and explicit measurements.

Evaluative conditioning may be an important mechanism for learning food preferences and aversions; however, in both real life and experimental settings it has not been consistently successful. The current study aimed to gain more insight into which underlying factors may contribute to a successful outcome of olfactory evaluative conditioning. Two groups of 18 participants came in on three consecutive days, and were repeatedly exposed to four novel, neutral odors (CS) coupled to varying disliked, neutral, liked, or no stimuli (taste and/or pictures, US), following a 50% reinforcement schedule, leading to 40 odor presentations per session.

New insights into BaP-induced toxicity: role of major metabolites in transcriptomics and contribution to hepatocarcinogenesis.

Benzo(a)pyrene (BaP) is a ubiquitous carcinogen resulting from incomplete combustion of organic compounds and also present at high levels in cigarette smoke. A wide range of biological effects has been attributed to BaP and its genotoxic metabolite BPDE, but the contribution to BaP toxicity of intermediary metabolites generated along the detoxification path remains unknown. Here, we report for the first time how 3-OH-BaP, 9,10-diol and BPDE, three major BaP metabolites, temporally relate to BaP-induced transcriptomic alterations in HepG2 cells.

Interindividual variation in gene expression responses and metabolite formation in acetaminophen-exposed primary human hepatocytes.

Acetaminophen (APAP) is a readily available over-the-counter drug and is one of the most commonly used analgesics/antipyretics worldwide. Large interindividual variation in susceptibility toward APAP-induced liver failure has been reported. However, the exact underlying factors causing this variability in susceptibility are still largely unknown.

Integrating multiple omics to unravel mechanisms of Cyclosporin A induced hepatotoxicity in vitro.

In order to improve attrition rates of candidate-drugs there is a need for a better understanding of the mechanisms underlying drug-induced hepatotoxicity. We aim to further unravel the toxicological response of hepatocytes to a prototypical cholestatic compound by integrating transcriptomic and metabonomic profiling of HepG2 cells exposed to Cyclosporin A. Cyclosporin A exposure induced intracellular cholesterol accumulation and diminished intracellular bile acid levels.

Interindividual variation in response to xenobiotic exposure established in precision-cut human liver slices.

Large differences in toxicity responses occur within the human population. In this study we evaluate whether interindividual variation in baseline enzyme activity (EA)/gene expression (GE) levels in liver predispose for the variation in toxicity responses by assessing dose-response relationships for several prototypical hepatotoxicants. Baseline levels of cytochrome-P450 (CYP) GE/EA were measured in precision-cut human liver slices.

Evaluation of database-derived pathway development for enabling biomarker discovery for hepatotoxicity.

Current testing models for predicting drug-induced liver injury are inadequate, as they basically under-report human health risks. We present here an approach towards developing pathways based on hepatotoxicity-associated gene groups derived from two types of publicly accessible hepatotoxicity databases, in order to develop drug-induced liver injury biomarker profiles. One human liver 'omics-based and four text-mining-based databases were explored for hepatotoxicity-associated gene lists.

Free radical scavenging and formation by multi-walled carbon nanotubes in cell free conditions and in human bronchial epithelial cells.

Background: Certain multi-walled carbon nanotubes (MWCNTs) have been shown to elicit asbestos-like toxicological effects. To reduce needs for risk assessment it has been suggested that the physicochemical characteristics or reactivity of nanomaterials could be used to predict their hazard. Fibre-shape and ability to generate reactive oxygen species (ROS) are important indicators of high hazard materials.

Classification of hepatotoxicants using HepG2 cells: A proof of principle study.

With the number of new drug candidates increasing every year, there is a need for high-throughput human toxicity screenings. As the liver is the most important organ in drug metabolism and thus capable of generating relatively high levels of toxic metabolites, it is important to find a reliable strategy to screen for drug-induced hepatotoxicity. Microarray-based transcriptomics is a well-established technique in toxicogenomics research and is an ideal approach to screen for drug-induced injury at an early stage.

Testing chemical carcinogenicity by using a transcriptomics HepaRG-based model?

The EU FP6 project carcinoGENOMICS explored the combination of toxicogenomics and in vitro cell culture models for identifying organotypical genotoxic- and non-genotoxic carcinogen-specific gene signatures. Here the performance of its gene classifier, derived from exposure of metabolically competent human HepaRG cells to prototypical non-carcinogens (10 compounds) and hepatocarcinogens (20 compounds), is reported. Analysis of the data at the gene and the pathway level by using independent biostatistical approaches showed a distinct separation of genotoxic from non-genotoxic hepatocarcinogens and non-carcinogens (up to 88 % correct prediction).

Characterisation of cisplatin-induced transcriptomics responses in primary mouse hepatocytes, HepG2 cells and mouse embryonic stem cells shows conservation of regulating transcription factor networks.

The toxic mechanisms of cisplatin have been frequently studied in many species and in vitro cell models. The Netherlands Toxicogenomics Centre focuses on developing in vitro alternatives using genomics technologies for animal-based assays on, e.g.

Pathways for ligand activated nuclear receptors to unravel the genomic responses induced by hepatotoxicants.

The liver is a vital organ in vertebrates that can be subject to disease, among others due to exposure to toxic xenobiotic compounds. A group of transcription factors named ligand activated nuclear receptors (LANR) influence and regulate important liver functions, and can be activated by many xenobiotic compounds, which thereby can cause hepatotoxicity. Systematic analysis of the gene pathways regulated by LANR using modern 'omics technologies is important for investigating modes-of-action of hepatotoxicants.

Micronuclei in cord blood lymphocytes and associations with biomarkers of exposure to carcinogens and hormonally active factors, gene polymorphisms, and gene expression: the NewGeneris cohort.

Background: Leukemia incidence has increased in recent decades among European children, suggesting that early-life environmental exposures play an important role in disease development.

Objectives: We investigated the hypothesis that childhood susceptibility may increase as a result of in utero exposure to carcinogens and hormonally acting factors. Using cord blood samples from the NewGeneris cohort, we examined associations between a range of biomarkers of carcinogen exposure and hormonally acting factors with micronuclei (MN) frequency as a proxy measure of cancer risk.

Baseline and genotoxic compound induced gene expression profiles in HepG2 and HepaRG compared to primary human hepatocytes.

Efforts are put into developing toxicogenomics-based toxicity testing methods using in vitro human cell models for improving human risk assessment/replacing animal models. Human in vitro liver models include HepG2, HepaRG and primary human hepatocytes (PHH). Studies on comparability/applicability of these cell types mainly focus on assessing baseline biotransformation capacities/cytochrome P450-inducibility, but compound-induced gene expression profiles are at least as important.

Cyclosporine A treated in vitro models induce cholestasis response through comparison of phenotype-directed gene expression analysis of in vivo Cyclosporine A-induced cholestasis.

In vitro models for hepatotoxicity testing are a necessity for advancement of toxicological research. Assessing the in vitro response requires in vivo validated gene sets reflective of the hepatotoxic phenotype. Cholestasis, the impairment of bile flow, is induced in C57BL/6J mice treated with cyclosporine A (CsA) to identify phenotype reflective gene sets.

A review on ochratoxin A transcriptomic studies.

The mycotoxin Ochratoxin A (OTA) is a potent renal carcinogen in male rats. Transcriptomic studies on OTA (4 in vitro, 6 in vivo, 2 in vitro/in vivo) have been reviewed. The aim of 6 of them was mainly mechanistic whereas the rest had mostly predictive (1) or evaluation (5) purposes.

Gender-specific transcriptomic response to environmental exposure in Flemish adults.

Flanders, Belgium, is one of the most densely populated areas in Europe. The Flemish Environment and Health Survey (2002-2006) aimed at determining exposure to pollutants of neonates, adolescents, and older adults and to assess associated biological and health effects. This study investigated genome wide gene expression changes associated with a range of environmental pollutants, including cadmium, lead, PCBs, dioxin, hexachlorobenzene, p,p'-DDE, benzene, and PAHs.

Transcriptomic responses generated by hepatocarcinogens in a battery of liver-based in vitro models.

As the conventional approach to assess the potential of a chemical to cause cancer in humans still includes the 2-year rodent carcinogenicity bioassay, development of alternative methodologies is needed. In the present study, the transcriptomics responses following exposure to genotoxic (GTX) and non-genotoxic (NGTX) hepatocarcinogens and non-carcinogens (NC) in five liver-based in vitro models, namely conventional and epigenetically stabilized cultures of primary rat hepatocytes, the human hepatoma-derived cell lines HepaRG and HepG2 and human embryonic stem cell-derived hepatocyte-like cells, are examined. For full characterization of the systems, several bioinformatics approaches are employed including gene-based, ConsensusPathDB-based and classification analysis.

Screening for drug-induced hepatotoxicity in primary mouse hepatocytes using acetaminophen, amiodarone, and cyclosporin a as model compounds: an omics-guided approach.

Drug-induced hepatotoxicity is a leading cause of attrition for candidate pharmaceuticals in development. New preclinical screening methods are crucial to predict drug toxicity prior to human studies. Of all in vitro hepatotoxicity models, primary human hepatocytes are considered as 'the gold standard.

Comparison of genotoxicant-modified transcriptomic responses in conventional and epigenetically stabilized primary rat hepatocytes with in vivo rat liver data.

The concept of mechanistic toxicogenomics implies that compound-induced changes in gene expression profiles provide valuable information about their mode of action. A growing number of research groups have presented evidence that whole-genome gene expression profiling techniques might be used as tools for in vivo and in vitro generation of gene signatures and elucidation of molecular mechanisms after exposure to toxic compounds. An important issue to be investigated is the in vivo relevance of in vitro-obtained data.

Performance of in vitro γH2AX assay in HepG2 cells to predict in vivo genotoxicity.

The γH2AX assay has recently been suggested as a new in vitro assay for detecting genotoxic (GTX) properties of chemicals. This assay is based on the phosphorylation of H2AX histone in response to DNA damage [i.e.

RNA-Seq provides new insights in the transcriptome responses induced by the carcinogen benzo[a]pyrene.

Whole-genome transcriptome measurements are pivotal for characterizing molecular mechanisms of chemicals and predicting toxic classes, such as genotoxicity and carcinogenicity, from in vitro and in vivo assays. In recent years, deep sequencing technologies have been developed that hold the promise of measuring the transcriptome in a more complete and unbiased manner than DNA microarrays. Here, we applied this RNA-seq technology for the characterization of the transcriptomic responses in HepG2 cells upon exposure to benzo[a]pyrene (BaP), a well-known DNA damaging human carcinogen.