Project description:For evaluating genotoxic exposure in human populations a number of biomarkers has been successfully applied over the last 30 years to determine early biological effects due to exposure to carcinogens. Despite their success, these early biological effects markers provide limited mechanistic insight, and are unable to detect exposure to non-genotoxic carcinogens. Gene expression profiling forms a promising tool for the development of new biomarkers in blood cells to overcome these limitations. The aim of our research was to identify novel genomics-based candidate markers for genotoxic and non-genotoxic carcinogen exposure. Whole genome gene expression changes were investigated in human blood cells following ex vivo exposure to a range of genotoxic and non-genotoxic carcinogenic compounds using whole genome microarrays. Sets of genes, as well as biological pathways indicative of genotoxic exposure and of non-genotoxic carcinogenic exposure were identified. Furthermore, networks were built using the genotoxic and non-genotoxic genes sets, showing the majority of the genes to be interlinked and revealing distinctive transcription factors for both classes. The identification of these potential candidate marker genes might contribute to the development of genomic based biomakers of genotoxic exposure, and possibly even more importantly biomarkers of exposure to non-genotoxic carcinogens since presently no biomarkers are available. Keywords: Genome wide gene expression analysis, Transcriptomic profile indicative of immunotoxic exposure
Project description:For evaluating genotoxic exposure in human populations a number of biomarkers has been successfully applied over the last 30 years to determine early biological effects due to exposure to carcinogens. Despite their success, these early biological effects markers provide limited mechanistic insight, and are unable to detect exposure to non-genotoxic carcinogens. Gene expression profiling forms a promising tool for the development of new biomarkers in blood cells to overcome these limitations. The aim of our research was to identify novel genomics-based candidate markers for genotoxic and non-genotoxic carcinogen exposure. Whole genome gene expression changes were investigated in human blood cells following ex vivo exposure to a range of genotoxic and non-genotoxic carcinogenic compounds using whole genome microarrays. Sets of genes, as well as biological pathways indicative of genotoxic exposure and of non-genotoxic carcinogenic exposure were identified. Furthermore, networks were built using the genotoxic and non-genotoxic genes sets, showing the majority of the genes to be interlinked and revealing distinctive transcription factors for both classes. The identification of these potential candidate marker genes might contribute to the development of genomic based biomakers of genotoxic exposure, and possibly even more importantly biomarkers of exposure to non-genotoxic carcinogens since presently no biomarkers are available. Keywords: Genome wide gene expression analysis, Transcriptomic profile indicative of immunotoxic exposure For analysis of whole genome gene expression by microarray, PBMC from five independent donors per compound were exposed for 20 hours to three concentrations, i.e. the 100% and two serial ten-fold dilutions (10% and 1%), and a DMSO or PBS vehicle control. Exposed samples were always labelled with Cy5, whereas the vehicle control samples were labelled with Cy3, and were competetively hybridized on 4x44K Agilent microarrays.
Project description:Investigating the immunotoxic effects of exposure to chemicals usually comprises evaluation of weight and histopathology of lymphoid tissues, various lymphocyte parameters in the circulation and immune function. Immunotoxicity assessment is time consuming in humans or requires a high number of animals, making it expensive. Furthermore, reducing the use of animals in research is an important ethical and political issue. Immunotoxicogenomics represents a novel approach to investigate immunotoxicity able of overcoming these limitations. The current research, embedded in the EU project NewGeneris, aimed to retrieve gene expression profiles that are indicative of exposure to immunotoxicants. To this end, whole genome gene expression was investigated in human peripheral blood mononuclear cells (PBMC) in response to in vitro exposure to a range of immunotoxic chemicals (4-hydroxy-2-nonenal, aflatoxin B1, benzo[a]pyrene, deoxynivalenol, ethanol, malondialdehyde, polychlorinated biphenyl 153, 2,3,7,8-tetrachlorodibenzo-p-dioxin) and non-immunotoxic chemicals (acrylamide, dimethylnitrosamine, 2-amino-3-methyl-3H-imidazo[4,5-F]quinoline, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine). Using Agilent oligonucleotide microarrays, whole genome gene expression profiles were generated, which were analysed using Genedata’s Expressionist® software. Using Recursive Feature Elimination and Support Vector Machine, a set of 48 genes was identified that distinguishes the immunotoxic from the non-immunotoxic compounds. Analysis for enrichment of biological processes showed the gene set to be highly biologically and immunologically relevant. We conclude that we have identified a transcriptomic profile indicative of immunotoxic exposure. Keywords: Genome wide gene expression analysis, Transcriptomic profile indicative of immunotoxic exposure
Project description:The increasing number of man-made chemicals in the environment that may pose a carcinogenic risk emphasizes the need for the development of reliable time- and cost-effective approaches for carcinogen detection. To address this issue, we have investigated the utility of human hepatocytes for the in vitro identification of genotoxic and non-genotoxic carcinogens. Induced pluripotent stem cell (iPSC)-derived human hepatocytes were treated with the genotoxic carcinogens aflatoxin B1 (AFB1) and benzo[a]pyrene (B[a]P) and with the non-genotoxic liver carcinogen methapyrilene at non-cytotoxic concentrations for 7 days, and transcriptomic profile was examined. 1569 (892 protein-coding and 677 non-coding), 1693 (922 protein-coding and 771 non-coding), and 2061 (1462 protein-coding and 599 non-coding) differentially expressed genes were detected in cells treated with AFB1, B[a]P, and methapyrilene, respectively. Additionally, we examined the toxicogenomics response to AFB1, B[a]P, and methapyrilene exposure in human HepaRG cells and demonstrated that carcinogens had a less prominent effect on the cellular transcriptome as compared to that in human iPSC-derived hepatocytes. Overall, the results demonstrate that the prime non-genotoxic effect of exposure to carcinogens, regardless of their mode of action, in short-term in vitro testing is a profound global transcriptome response, indicating a greater value of toxicogenomics for rapid carcinogen screening in vitro.
Project description:We performed whole-genome transcriptomic profiling of RNA from mononuclear cells from bone marrow aspirates taken from healthy individuals. This study complements GSE58335: transcriptomic profiling of peripheral blood mononuclear cells from healthy individuals.
Project description:N-nitroso compounds (NOCs) can be formed through endogenous nitrosation in the human body and are known to induce micronuclei (MN) formation in vitro. Since lymphocytic MN represent a well-validated biomarker of effect with regard to carcinogenic risk in multiple target organs, establishing a link between NOCs and MN in humans could provide evidence for a carcinogenic risk. Investigating gene expression modulations in relation to NOC exposure could provide further crucial information on underlying molecular mechanisms-of-action. The purpose of this study is therefore to establish the relationship between human NOC exposure under daily life conditions and MN formation in relation to associated transcriptomic changes, using lymphocytes as a surrogate tissue for analyzing carcinogenic events in target organs. We analyzed gene expression levels and MN frequency in lymphocytes from adults participating in a European cohort from the multidisciplinary research project NewGeneris. For assessing exposure to NOCs, urinary samples were analyzed for marker nitrosamines by GC-MS. NOC exposure was subsequently linked to peripheral blood transcriptomics. We found an association between MN frequency and urinary NOCs, indicating that NOC exposure under daily life circumstances may play an important role in human cancer development. Furthermore, we have identified modifications in pathways which indicate a molecular response to NOC-induced genotoxicity. From this, we derived a small group of genes which could be suitable as mechanistic-based transcriptomic biomarkers of NOC exposure-related cancer risk. The modified genetic processes and genes found in this study may be of interest for future investigations into NOC-associated carcinogenicity in humans. The study investigated transcription levels in human whole blood from 30 pregnant mothers in a Danish NewGeneris cohort. For each subject, cRNA copies of isolated mRNA were labeled with one dye (Cy3) and each sample was hybridized on separate arrays. One replicate per subject (so 30 arrays in total).
Project description:The human body is continuously exposed to various compounds that could initiate or accelerate cancer development. Such carcinogenic compounds can be classified into a genotoxic and non-genotoxic group. Especially carcinogenicity of non-genotoxic compounds is difficult to determine with current in vitro assessments and therefore has to be improved urgently. Here, we used a toxicogenomics-based approach by genome-wide microRNA expression profiling of mouse embryonic stem (mES) cells to identify microRNA classifiers for genotoxic carcinogens (GTXC), non-genotoxic carcinogens (NGTXC) and oxidative (Ox) compounds. We exposed mES cells to four different NGTXC, four GTXC and four Ox compounds. Differential microRNA expression was determined 4, 8 and 12 hours after exposure and was used to assess its discriminative power for NGTXC and GTXC. We generated an accurate classifier set, which was discriminative for NGTXC using a tiered approach. In conclusion, our study indicates that microRNA expression profiles can discriminate between NGTXC, GTXC and Ox compounds with high accuracy.