High-Throughput Transcriptomic Profiling for Bioactivity Screening: Mapping Molecular Targets and Potencies for PFAS chemicals in HepaRG Cells
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE296248 | GEO | 2025/11/21
REPOSITORIES: GEO
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Project description:Since initial regulatory action in 2010 in Canada, bisphenol A (BPA) has been progressively replaced by structurally related alternative chemicals. Unfortunately, many of these chemicals are data-poor, limiting toxicological risk assessment. We used high-throughput transcriptomics to evaluate potential hazards and compare potencies of BPA and 15 BPA alternative chemicals in cultured breast cancer cells. MCF-7 cells were exposed to BPA and 15 alternative chemicals (0.0005 – 100 µM) for 48 hrs. TempO-Seq sequencing (BioSpyder Inc.) was used to examine general toxicological effects and estrogen receptor alpha (ERα)-associated transcriptional changes. Benchmark concentration (BMC) analysis was conducted to identify two global transcriptomic points of departure (tPODs): (a) the lowest pathway median gene BMC and (b) the 25th lowest rank-ordered gene BMC. ERα activation was evaluated using a published transcriptomic biomarker and an ERα-specific tPOD was derived. Genes fitting BMC models were subjected to upstream regulator and canonical pathway analysis in Ingenuity Pathway Analysis. Biomarker analysis identified BPA and eight alternative chemicals as ERα active. Global and ERα tPODs produced highly similar potency rankings with BPAF as the most potent chemical tested, followed by BPA, BPC, 4,4’-BPF, BPAP, BPS, BADGE, 2,4’-BPF, Pergafast201®, D-8, 2,4’-BPS, TGSA, and BPS-MAE. Further, BPA and transcriptionally active alternative chemicals enriched similar gene sets associated with increased cell division and cancer-related processes. These data provide support for future read-across applications of transcriptomic profiling for risk assessment of data-poor chemicals and suggest that several BPA alternative chemicals may cause hazards at similar concentrations to BPA.
2022-08-18 | GSE211183 | GEO
Project description:Traditional toxicity testing has been unable to keep pace with the introduction of new chemicals into commerce. Consequently, there are limited or no toxicity data upon which to base a risk assessment for many chemicals to which fish and wildlife may be exposed. Per- and polyfluoroalkyl substances (PFAS) are emblematic of this issue in that most the ecological hazards of most PFAS remain uncharacterized. The present study employed a high throughput assay to identify the concentration at which 20 PFAS, with diverse properties, elicited a concerted gene expression response in larval fathead minnows (Pimephales promelas, 5-6 days post-fertilization) exposed for 24 h. Based on a reduced transcriptome approach that measured whole body expression of 1832 genes, the median transcriptomic point of departure (tPOD) for the 20 PFAS tested was 10 µM. Longer chain carboxylic acids (12-13 C-F) and an eight C-F di-alcohol, N-alkyl sulfonamide, and telomer sulfonic acid were among the most potent PFAS, eliciting gene expression responses at concentrations below 1 µM. With a few exceptions, larval fathead minnow tPODs were concordant with those based on whole transcriptome response in human cell lines. However, larval fathead minnow tPODs were often greater than those for Daphnia magna exposed to the same PFAS. The tPODs overlapped concentrations at which other sub-lethal effects have been reported in fish (available for 10 PFAS; including a range of species, life stages, and study designs). Nonetheless, fathead minnow tPODs were all orders of magnitude higher than aqueous PFAS concentrations detected in tributaries of the North American Great Lakes suggesting a substantial margin of safety in those systems, even for PFAS with significant potential for bioaccumulation. Overall, results broadly support the use of a fathead minnow larval transcriptomics assay to derive screening level potency estimates for use in ecological risk-based prioritization. Traditional toxicity testing has been unable to keep pace with the introduction of new chemicals into commerce. Consequently, there are limited or no toxicity data upon which to base a risk assessment for many chemicals to which fish and wildlife may be exposed. Per- and polyfluoroalkyl substances (PFAS) are emblematic of this issue in that most the ecological hazards of most PFAS remain uncharacterized. The present study employed a high throughput assay to identify the concentration at which 20 PFAS, with diverse properties, elicited a concerted gene expression response in larval fathead minnows (Pimephales promelas, 5-6 days post-fertilization) exposed for 24 h. Based on a reduced transcriptome approach that measured whole body expression of 1832 genes, the median transcriptomic point of departure (tPOD) for the 20 PFAS tested was 10 µM. Longer chain carboxylic acids (12-13 C-F) and an eight C-F di-alcohol, N-alkyl sulfonamide, and telomer sulfonic acid were among the most potent PFAS, eliciting gene expression responses at concentrations below 1 µM. With a few exceptions, larval fathead minnow tPODs were concordant with those based on whole transcriptome response in human cell lines. However, larval fathead minnow tPODs were often greater than those for Daphnia magna exposed to the same PFAS. The tPODs overlapped concentrations at which other sub-lethal effects have been reported in fish (available for 10 PFAS; including a range of species, life stages, and study designs). Nonetheless, fathead minnow tPODs were all orders of magnitude higher than aqueous PFAS concentrations detected in tributaries of the North American Great Lakes suggesting a substantial margin of safety in those systems, even for PFAS with significant potential for bioaccumulation. Overall, results broadly support the use of a fathead minnow larval transcriptomics assay to derive screening level potency estimates for use in ecological risk-based prioritization.
2024-10-23 | GSE246120 | GEO
Project description:Understanding the mechanisms by which environmental chemicals cause toxicity is necessary for effective human health risk assessment. High-Throughput Transcriptomics (HTTr) can be used to inform risk assessment on toxicological mechanisms, hazards, and potencies. We applied HTTr to elucidate the molecular mechanisms by which Per- and Polyfluoroalkyl Substances (PFAS) cause liver toxicity. We contrasted transcriptomic profiles of four prototype PFAS against transcriptomic profiles from liver-toxic and non-liver-toxic reference compounds, alongside chemicals that activate peroxisome proliferator-activated receptors (PPARs). Our analysis was conducted on metabolically competent 3-D human liver spheroids produced from primary cells of 10 donors. Pathway analysis showed that PFOS and PFDS perturb many of the same pathways as the liver-toxic compounds in the spheroids, and that the cholesterol biosynthesis pathways are significantly affected by exposure to these compounds. PFOA alters lipid metabolism-related pathways but its expression profile does not closely match reference compounds. PFBS upregulates many degradation-related pathways and targets many of the same pathways as the PPAR agonists and acetaminophen. Our transcriptional analysis does not support that these PFAS are DNA damaging in this model. A multidimensional scaling analysis revealed that PFOS, PFOA, and PFDS cluster together in the same 3-D space as liver-damaging compounds; whereas, PFBS clusters more closely with the non-liver-damaging compounds. Benchmark concentration-response modeling predicts that all the PFAS are sufficiently bioactive to be liver-toxic. Overall, our results show that these PFAS produce unique transcriptional changes as well as altering pathways associated with established liver-toxic chemicals in this liver spheroid model.
2025-02-17 | GSE272576 | GEO
Project description:High-throughput transcriptomics (HTTr) was undertaken to quantify and characterize the biological effects of chemicals observed in human-derived in vitro test systems. A set of 137 structurally diverse PFAS was tested using the HTTr assay in the human-derived cell type U-2 OS (osteosarcoma). The PFAS studies were carried out as a part of a larger screening study of a total of 1323 chemicals. Chemicals were randomized to treatment plates (cells plus media) in triplicate. Plates also contained reference treatments for quality control purposes. The TempO-Seq human whole transcriptome assay (Yeakley et al., 2017) was used to identify biological pathway altering concentrations (BPACs) and characterize the biological activity of test chemicals. For this analysis, a catalog of 11,037 gene expression signatures collated from multiple public sources were analyzed using concentration-response modeling of signature enrichment scores determined using single-sample gene set enrichment analysis (ssGSEA) (Barbie et al. 2009) with DESeq2-moderated fold change values as input (Love et al. 2014). A sample was considered active if 25 or more signatures were concentration-responsive and the BPAC was calculated as the 5th percentile of benchmark concentrations (BMCs) of active signatures.
2025-06-17 | GSE297135 | GEO
Project description:Multiple new approach methods (NAMs) are being developed to rapidly screen large numbers of chemicals to aid in hazard evaluation and risk assessments. High-throughput transcriptomics (HTTr) in human cell lines has been proposed as a first-tier screening approach for determining the types of bioactivity a chemical can cause (activation of specific targets vs. generalized cell stress) and for calculating transcriptional points of departure (tPODs) based on changes in gene expression. In the present study, we examine a range of computational methods to calculate tPODs from HTTr data, using six data sets in which MCF7 cells cultured in two different media formulations were treated with a panel of 44 chemicals for 3 different exposure durations (6, 12, 24 hr).
2023-12-05 | GSE249377 | GEO
Project description:With thousands of chemicals in commerce and the environment, rapid identification of potential hazards is a critical need. Combining broad molecular profiling with targeted in vitro assays, such as high-throughput transcriptomics (HTTr) and receptor screening assays, could improve identification of chemicals that perturb key molecular targets associated with adverse outcomes. We aimed to link transcriptomic readouts to individual molecular targets and integrate transcriptomic predictions with orthogonal receptor-level assays in a proof-of-concept framework for chemical hazard prioritization. Transcriptomic profiles generated via TempO-Seq in U-2 OS and HepaRG cell lines were used to develop signatures comprised of genes uniquely responsive to reference chemicals for distinct molecular targets. These signatures were applied to 75 reference and 1,126 non-reference chemicals screened via HTTr in both cell lines. Selective bioactivity towards each signature was determined by comparing potency estimates against the bulk of transcriptomic bioactivity for each chemical. Chemicals predicted by transcriptomics were confirmed for target bioactivity and selectivity using available orthogonal assay data from US EPA’s ToxCast program. A subset of 37 selectively acting chemicals from HTTr that did not have sufficient orthogonal data were prospectively tested using one of five receptor-level assays. Of the 1,126 non-reference chemicals screened, 201 demonstrated selective bioactivity in at least one transcriptomic signature, and 57 were confirmed as selective nuclear receptor agonists. Chemicals bioactive for each signature were significantly associated with orthogonal assay bioactivity, and signature-based points-of-departure were equally or more sensitive than biological pathway altering concentrations in 81.2% of signature-prioritized chemicals. Prospective profiling found that 18 of 37 (49%) chemicals without prior orthogonal assay data were bioactive against the predicted receptor. Our work demonstrates that integrating transcriptomics with targeted orthogonal assays in a tiered framework can support Next Generation Risk Assessment by informing putative molecular targets and prioritizing chemicals for further testing. NOTE: this GEO entry only includes the HepaRG cell line data; the U-2 OS cell line data can be located via GEO accession number GSE274318.
2025-03-25 | GSE284321 | GEO
Project description:Per- and polyfluoroalkyl substances (PFAS) represent a large group of contaminants of concern based on their widespread use, distribution and persistence in the environment, and potential toxicity. Many of the traditional models for estimating toxicity, bioaccumulation, and other relevant toxicological properties are not well suited for PFAS. Consequently, there is a need to generate hazard information for a large number of PFAS in an efficient and cost-effective manner. In the present study, Daphnia magna were exposed to multiple concentrations of 22 different PFAS for 24 h, in a 96-well plate format. Following exposure, whole body RNA was extracted and pooled extracts, each representing five exposed individuals, were subjected to RNA sequencing. Following analytical measurements to verify PFAS exposure concentrations in-well, and quality control on processed cDNA libraries for sequencing, concentration-response modeling was applied to the data sets for 18 of the tested compounds, and the concentration at which a concerted molecular response occurred (transcriptomic point of departure; tPOD) was calculated. The tPODs, based on average measured concentration of PFAS in the exposure wells, generally ranged from 0.03-0.58 µM (9.9-350 µg/L; interquartile range). In most cases, these concentrations were two orders of magnitude lower than similarly calculated tPODs for human cell lines exposed to PFAS. They were also lower than apical effect concentrations reported for seven PFAS for which some crustacean or invertebrate toxicity data were available, although there were a few exceptions. However, despite being lower than most other available hazard benchmarks, the Daphnia magna tPODs were, on average, four orders of magnitude greater than the maximum aqueous concentrations of PFAS measured in Great Lakes tributaries. Overall, this high throughput transcriptomics assay with Daphnia magna holds promise as a component of a tiered hazard evaluation strategy employing new approach methodologies.
2024-02-22 | GSE245268 | GEO
Project description:Bisphenol A (BPA), a widely used chemical in the production of plastics and epoxy resins, has garnered significant attention due to its association with adverse health effects, particularly its endocrine-disrupting properties. Regulatory measures aimed at reducing human exposure to BPA have led to a proliferation of alternative chemicals used in various consumer products. While these alternatives serve to reduce BPA exposure, concerns have arisen regarding their safety and potential toxicity as regrettable substitutes. Previous efforts have demonstrated that in vitro high-throughput transcriptomics (HTTr) studies can be used to assess the endocrine-disrupting potential of BPA alternatives, and this strategy produces transcriptomic points-of-departure (tPoDs) that are protective of human health when compared to the PODs from traditional rodent studies. In this study, we leveraged in vitro HTTr advancements to assess the toxicity of eleven data-poor legacy chemicals sharing structural similarities to BPA. Human breast cancer MCF-7 cells were exposed to BPA and 11 alternatives at concentrations ranging from (0.1 - 25 µM) to assess toxicity. Analysis of global transcriptomic changes and a previously characterized estrogen receptor alpha (ERα) biomarker signature revealed that 9/11 chemicals were bioactive. One of the chemicals (2,4’-Bisphenol A) activated the ERα biomarker at the same concentration as BPA (i.e., 4,4’-BPA) but was deemed to be more potent as it induced global transcriptomic changes at lower concentrations. These results are addressing data gaps in ongoing screening assessments to identify BPA alternatives with hazard potential and are helping to identify potential candidates to serve as safer alternatives.
2024-08-26 | GSE271332 | GEO
Project description:Due to their environmental prevalence, persistence, and potential toxicity, per- and polyfluoroalkyl substances (PFAS) are contaminants of concern. However, except for a few well studied PFAS, hazard data required to evaluate their risk to aquatic ecosystems are limited. The present study used a 24-hour, high throughput assay to screen 22 PFAS with varying chain lengths and functional groups for effects on the transcriptome of a green algal species, Raphidocelis subcapitata. The tested PFAS included perfluoroalkyl carboxylic acids, perfluoroalkyl carboxylic acid ethers, alcohols, sulfonic acids, and sulfonamides. Algae were exposed in a 96-well microplate format to 8 concentrations (nominally, 100 to 0.03 uM) of each PFAS, in a 1/2 log dilution series. Analytical measurements of PFAS concentration were made at the initiation of exposure and after 24 hours. In addition to traditional endpoints (i.e., biomass, viability, and chlorophyll), RNA was extracted for sequencing of the transcriptome. Concentration response curves were fit to the resulting transcriptomic data to calculate gene-specific benchmark concentrations. The distribution of benchmark concentrations was subsequently used to calculate a transcriptomic point of departure (tPOD) which represents a concentration below which no concerted molecular change is detected in response to PFAS exposure. The resulting tPODs were compared with traditional endpoints and environmentally detected concentrations of specific PFAS.
2025-06-06 | GSE269539 | GEO
Project description:Per- and polyfluoroalkyl substances (PFAS) are some of the most prominent organic contaminants in human blood that have the potential to disrupt biological processes and pathways in the liver. Although the toxicological implications from human exposure to perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are well established, data on other, lesser-understood PFAS are limited. A challenge for regulatory authorities is to determine acceptable levels of human exposure to large, diverse classes of environmental contaminants. New approach methodologies (NAMs) that apply bioinformatics tools to interpret biological data are being increasingly considered to inform risk assessment when traditional toxicology methodologies are not amenable. The aim of the current investigation was to identify the biological responses relevant to PFAS mode of action as the concentration (benchmark dose) that these effects take place in order to utililze this information to inform/facilitate read-across for risk assessment of data-poor PFAS. A TempO-Seq platform (BioSpyder) measured gene expression changes in human liver microtissues (i.e., spheroids) after 1-day and 10-day exposures to increasing concentrations of PFAS. A bioinformatics framework was applied to 23 PFAS sub-classed into carboxylates (PFCAs), sulfonates (PFSAs), or PFAS precursors that were analyzed for the total altered transcripts, the concentration where effects take place, and identifying target genes of interest. Both PFCAs and PFSAs exhibited a trend toward increased transcriptional changes with carbon chain-length. Specifically, longer-chain compounds (7 to 10 carbons) were more likely to surpass liver-toxic transcriptomic thresholds established from previous studies than shorter chain PFAS. Longer-chain PFAS were also more potent, inducing transcriptional effects at lower concentrations. However, PFOS was the most potent PFAS and of all precursors, only PFOSA (a PFOS precursor) induced a response. The combined high-throughput transcriptomic and bioinformatics analyses revealed the capability of NAMs to assess the effects of PFAS in liver microtissues; such data improves our understanding of PFAS-related effects in humans and facilitates the use of read-across in human health risk assessment for other data-poor chemicals.
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