Assessment of the Performance of the TGx-DDI Biomarker to Detect DNA Damage-Inducing Agents Using Quantitative RT- PCR in TK6 Cells
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PROVIDER: PRJNA497584 | ENA |
REPOSITORIES: ENA
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Project description:Gene expression biomarkers are now available for application in the identification of genotoxic hazards. The TGx-DDI transcriptomic biomarker can accurately distinguish DDI from non-DDI exposures based on changes in the expression of 64 biomarker genes. The bioamarker was originally derived from DNA microarray gene expression profiles of TK6 human lymphoblastoid cells post 4-hour exposure to 28 reference DDI and non-DDI agents [Li et al. 2015]. To broaden the applicability of TGx-DDI, the biomarker was tested using quantitative RT-PCR (qPCR), which is accessible to most molecular biology laboratories. To assess the classification capability of the biomarker using qPCR, a custom 96-well TaqMan qPCR array (TGx-DDI qPCR array) was constructed using the 64 biomarker genes. TK6 cells were exposed to each of the 28 reference agents and their vehicle controls for 4 hours and the expression level of the TGx-DDI genes were profiled using the TaqMan arrays. This study provides reference qPCR expression profiles of the TGx-DDI biomarker for DDI chemical classification using qPCR.
2018-12-21 | GSE121532 | GEO
Project description:Transcriptomic signatures, or biomarkers, of toxicity can facilitate rapid mechanistic analysis of chemicals using high-content transcriptomic data and identification of potential hazards to human health. We developed an 81-gene transcriptomic biomarker, named TGx-HDACi, to detect histone deacetylase inhibitors (HDACi) in TK6 human lymphoblastoid cells after 4 hours of chemical exposure. This work leveraged an established transcriptomic biomarker of DNA damage, TGx-DDI, which was developed by Heng Hong Li et al. (2015); TGx-DDI contains 63 genes and can distinguish between DNA damage-inducing (DDI) and non-DDI agents after 4 hours of exposure in TK6 cells. TGx-HDACi was derived from Templated Oligo-Sequencing (TempO-Seq) whole transcriptome gene expression profiles of 20 reference compounds, consisting of 10 HDACi and 10 non-HDACi compounds. Fourteen of the TGx-HDACi reference compounds are also part of the 28-compound reference set for TGx-DDI. The nearest shrunken centroid (NSC) method was applied to the gene expression profiles and 81 genes were identified that accurately identified HDACi compounds in the NSC probability analysis. The classification performance of TGx-HDACi was validated using an additional set of 11 test compounds (4 HDACi and 7 non-HDACi). Thus far, TGx-HDACi has demonstrated 100% accuracy. The availability of TGx-HDACi increases the diversity of tools that can facilitate mode of action analysis of toxicants using gene expression profiling.
2021-04-14 | GSE164478 | GEO
Project description:The TGx-DDI is a transcriptomic biomarker used to predict the DNA damage-inducing (DDI) capability of chemicals by providing mechanistic information to aid in the interpretation of positive genotoxicity data. The biomarker was developed within the Health and Environmental Sciences Institute (HESI) and measures transcriptional changes in a set of primarily p53-responsive genes. We investigated three antibiotic drugs, nitrofurantoin (NIT), novobiocin sodium salt (NOV) and metronidazole (MTZ), with a long history of clinical use in human and/or veterinary applications. While all three drugs are considered safe, there is some evidence of chromosome damage with NIT and NOV. We conducted high-throughput CometChip and TGx-DDI assays to evaluate the drugs in a parallel test strategy to explore their toxicity using these newer mechanism-based tests. An extended concentration-response analysis was conducted in human TK6 cells (from 0 to 1 mM). The alkaline CometChip assay was used to measure DNA damage, while TGx-DDI was applied using TempO-Seq and NanoString technologies (in two different laboratories) to confirm reproducibility of the results. The CometChip was negative for all three drugs except at overtly cytotoxic concentrations, which were eliminated from the gene expression analysis. NIT and MTZ were classified as non-DDI by TGx-DDI at all concentrations tested. NOV classified as DDI at the highest concentrations tested. NOV is bacterial DNA-gyrase inhibitor that also acts as a topoisomerase II inhibitor at high concentrations. The TGx-DDI classification results were identical across laboratories/technologies. This case study demonstrates the utility of TGx-DDI to de-risk NIT and NOV, and the reproducibility of the biomarker.
2022-08-02 | GSE196369 | GEO
Project description:The TGx-DDI is a transcriptomic biomarker used to predict the DNA damage-inducing (DDI) capability of chemicals by providing mechanistic information to aid in the interpretation of positive genotoxicity data. The biomarker was developed within the Health and Environmental Sciences Institute (HESI) and measures transcriptional changes in a set of primarily p53-responsive genes. We investigated three antibiotic drugs, nitrofurantoin (NIT), novobiocin sodium salt (NOV) and metronidazole (MTZ), with a long history of clinical use in human and/or veterinary applications. While all three drugs are considered safe, there is some evidence of chromosome damage with NIT and NOV. We conducted high-throughput CometChip and TGx-DDI assays to evaluate the drugs in a parallel test strategy to explore their toxicity using these newer mechanism-based tests. An extended concentration-response analysis was conducted in human TK6 cells (from 0 to 1 mM). The alkaline CometChip assay was used to measure DNA damage, while TGx-DDI was applied using TempO-Seq and NanoString technologies (in two different laboratories) to confirm reproducibility of the results. The CometChip was negative for all three drugs except at overtly cytotoxic concentrations, which were eliminated from the gene expression analysis. NIT and MTZ were classified as non-DDI by TGx-DDI at all concentrations tested. NOV classified as DDI at the highest concentrations tested. NOV is bacterial DNA-gyrase inhibitor that also acts as a topoisomerase II inhibitor at high concentrations. The TGx-DDI classification results were identical across laboratories/technologies. This case study demonstrates the utility of TGx-DDI to de-risk NIT and NOV, and the reproducibility of the biomarker.
2022-08-02 | GSE196372 | GEO
Project description:Gene expression biomarkers are now available for application in the identification of genotoxic hazards. The TGx-DDI transcriptomic biomarker can accurately distinguish DNA damage-inducing (DDI) from non-DDI exposures based on changes in the expression of 64 biomarker genes. The 64 genes were previously derived from whole transcriptome DNA microarray profiles of 28 reference agents (14 DDI and 14 non-DDI) after 4 h treatments of TK6 human lymphoblastoid cells. To broaden the applicability of TGx-DDI, we tested the biomarker using quantitative RT-PCR (qPCR), which is accessible to most molecular biology laboratories. First, we selectively profiled the expression of the 64 biomarker genes using TaqMan qPCR assays in 96-well arrays after exposing TK6 cells to the 28 reference agents for 4 h. To evaluate the classification capability of the qPCR profiles, we used the reference qPCR signature to classify 24 external validation chemicals using two different methods-a combination of three statistical analyses and an alternative, the Running Fisher test. The qPCR results for the reference set were comparable to the original microarray biomarker; 27 of the 28 reference agents (96%) were accurately classified. Moreover, the two classification approaches supported the conservation of TGx-DDI classification capability using qPCR; the combination of the two approaches accurately classified 21 of the 24 external validation chemicals, demonstrating 100% sensitivity, 81% specificity, and 91% balanced accuracy. This study demonstrates that qPCR can be used when applying the TGx-DDI biomarker and will improve the accessibility of TGx-DDI for genotoxicity screening. Environ. Mol. Mutagen. 60: 122-133, 2019. © 2018 Her Majesty the Queen in Right of Canada Environmental and Molecular Mutagenesis.
| S-EPMC6588084 | biostudies-literature
Project description:Cell-based application of a transcriptomic biomarker, TGx-DDI, in addressing potentially irrelevant positive findings in chromosome damage assays
2017-11-21 | GSE107162 | GEO
Project description:Background: Modern testing paradigms seek to apply human-relevant cell culture models and integrate data from multiple test systems to accurately inform potential hazards and modes of action for chemical toxicology. In genetic toxicology, the use of metabolically competent human hepatocyte cell culture models provides clear advantages over other more commonly used cell lines that require the use of external metabolic activation systems, such as rat liver S9. HepaRG™ cells are metabolically competent cells that express Phase I and II metabolic enzymes and differentiate into mature hepatocyte-like cells, making them ideal for toxicity testing. We assessed the performance of the flow cytometry in vitro micronucleus (MN) test and the TGx-DDI transcriptomic biomarker to detect DNA damage-inducing (DDI) chemicals in human HepaRG™ cells after a 3-day repeat exposure. The biomarker, developed for use in human TK6 cells, is a panel of 64 genes that accurately classifies chemicals as DDI or non-DDI. Herein, the TGx-DDI biomarker was analyzed by Ion AmpliSeq whole transcriptome sequencing to assess its classification accuracy using this more modern gene expression technology as a secondary objective. Methods: HepaRG™ cells were exposed to increasing concentrations of 10 test chemicals (six genotoxic chemicals, including one aneugen, and four non-genotoxic chemicals). Cytotoxicity and genotoxicity were measured using the In Vitro MicroFlow® kit, which was run in parallel with the TGx-DDI biomarker. Results: A concentration-related decrease in relative survival and a concomitant increase in MN frequency were observed for genotoxic chemicals in HepaRG™ cells. All five DDI and five non-DDI agents were correctly classified (as genotoxic/non-genotoxic and DDI/non-DDI) by pairing the test methods. The aneugenic agent (colchicine) yielded the expected positive result in the MN test and negative (non-DDI) result by TGx-DDI. Conclusions: This next generation genotoxicity testing strategy is aligned with the paradigm shift occurring in the field of genetic toxicology. It provides mechanistic insight in a human-relevant cell-model, paired with measurement of a conventional endpoint, to inform the potential for adverse health effects. This work provides support for combining these assays in an integrated test strategy for accurate, higher throughput genetic toxicology testing in this metabolically competent human progenitor cell line.
2020-02-18 | GSE136009 | GEO
Project description:In vitro toxicogenomics signatures to predict mode of action can facilitate chemical screening. We recently demonstrated the use of the TGx-28.65 genomic biomarker (representing: toxicogenomics (TGx), developed using a 28 chemical training set, and comprising 65 genes) in classifying agents as genotoxic (DNA damaging) and non-genotoxic in human lymphoblastoid TK6 cells. Because TK6 cells do not possess cytochrome P450 activity, we confirmed accurate classification in cells co-exposed to 1% 5,6 benzoflavone/phenobarbital-induced rat liver S9 for metabolic activation. However, chemicals may require different types of S9 for activation. Here we conducted experiments in TK6 cells exposed to chemicals in the presence of 2% or 10% Aroclor-induced, or 5% ethanol-induced rat liver S9 to expand TGx-28.65 biomarker application. Gene expression profiles were produced 3-4 hr following a 4 hr co-exposure of TK cells to test chemicals (seven genotoxic and two non-genotoxic, three concentrations, and concurrent solvent controls) and S9. Relative survival and micronucleus frequency was assessed by flow cytometry in cells 20 hr after the exposure. We found that genotoxicity/non-genotoxicity could be accurately predicted for the test compounds using the different S9s. One technical replicate of cells co-treated with dexamethasone and 10% Aroclor-induced S9 was falsely predicted as genotoxic, suggesting caution in using high concentrations of S9. TGx-28.65 correctly classified low concentrations of genotoxic chemicals (those not causing cytotoxicity or micronuclei) as genotoxic, demonstrating that it is a sensitive biomarker of genotoxicity. Overall, the work confirms that different S9s can be used in TK6 cells without impairing predictivity using the TGx-28.65 biomarker.
2016-08-25 | GSE74216 | GEO
Project description:Application of the transcriptomic biomarker, TGx-DDI, in genotoxicity screening
| PRJNA419190 | ENA
Project description:Introduction: Higher-throughput mode-of-action-based assays provide a valuable approach to expedite chemical evaluation for human health risk assessment. In this study, we combined the high-throughput alkaline CometChip® assay with the TGx-DDI transcriptomic biomarker (DDI = DNA damage-inducing) using high-throughput TempO-Seq® as an integrated genotoxicity testing approach. Objective: To determine if the high-throughput CometChip® assay and TGx-DDI biomarker analysis can be combined using human HepaRG™ cells to provide an efficient next-generation genotoxicity screening approach to identify DNA damage-inducing (DDI) chemicals. Methods: Metabolically competent human HepaRG™ cell cultures were exposed to increasing concentrations of 12 chemicals (9 DDI and 3 non-DDI) using a repeat exposure design (0 hr, 24 hr, 48 hr) in 96-well plates to measure and classify chemicals based on their ability to damage DNA. After a 4 hr recovery period, exposed cells were used to perform the Trevigen CometChip assay to assess DNA damage or used for TempO-Seq® S1500+ Targeted Transcriptome Sequencing for TGx-DDI classification purposes. Bioinformatics and statistical tools were used to classify chemicals as DDI or non-DDI using three separate analyses. Benchmark concentration analysis was also conducted for both assays for the purposes of potency ranking. Results: In combination, the CometChip® assay and the TGx-DDI were 100% accurate in identifying chemicals that induce DNA damage. Quantitative benchmark concentration (BMC) modeling was applied to evaluate chemical potencies for both assays. The BMCs for the CometChip® assay and the TGx-DDI for all 12 chemicals were highly concordant (within four-fold) and resulted in identical potency rankings. Conclusions: These results suggest that these two assays can be integrated for efficient, high-throughput identification of DNA damage in HepaRG™ cells. This study provides evidence for the complementarity of the high-throughput CometChip® assay with TGx-DDI biomarker analysis. Integration of these two tests provides an effective and high-throughput approach to identify DDI agents. This work is a first step in accomplishing a more integrated genotoxicity testing strategy to derive mechanistic information to better inform human health risk assessment in a high-throughput manner.
2021-07-21 | GSE171360 | GEO