High-throughput transcriptomic (HTTr) technologies are increasingly being used to screen environmental chemicals in vitro to identify molecular targets and provide mechanistic context for regulatory testing. The androgen receptor (AR, NR3C4) regulates male sexual development, is involved in the pathogenesis of a number of cancers, and is often the target of endocrine disruptors. Here, we describe the development and validation of a novel gene expression biomarker to identify AR-modulating chemicals using a pattern matching method. AR biomarker genes were identified by their consistent expression after exposure to 4 AR agonists and opposite expression after exposure to 4 AR antagonists. A genetic filter was used to include only those genes that were regulated by AR. Most of the resulting 51 biomarker genes were shown to be directly regulated by AR as determined by ChIP-Seq analysis of AR-DNA interactions. The biomarker was evaluated as a predictive tool using the fold-change rank-based Running Fisher algorithm which compares the expression of AR biomarker genes under various treatment conditions. Using 163 comparisons from cells treated with 98 chemicals, the biomarker gave balanced accuracies for prediction of AR activation or AR suppression of 97% or 98%, respectively. The biomarker was able to correctly classify 16 out of 17 AR reference antagonists including those that are weak and very weak. Predictions based on comparisons from AR-positive LAPC-4 cells treated with 28 chemicals in antagonist mode were compared to those from an AR pathway model based on 11 in vitro high-throughput screening assays that queried different steps in AR signaling. The balanced accuracy was 93% for suppression. Using our approach, we identified conditions in which AR was modulated in a large collection of microarray profiles from prostate cancer cell lines including 1) AR constitutively active mutants or knockdown of AR, 2) depletion of androgens by castration or removal from media, and 3) modulators that work through indirect mechanisms including suppression of AR expression. These results demonstrate that the AR gene expression biomarker could be a useful tool in HTTr to identify AR modulators in large collections of microarray data derived from AR-positive prostate cancer cell lines.
Identification of Androgen Receptor Modulators in a Prostate Cancer Cell Line Microarray Compendium.
Specimen part, Cell line
View SamplesDetermining mechanism-based biomarkers that distinguish adaptive and adverse cellular processes is critical to understanding the health effects of environmental exposures. Shifting from in vivo, low-throughput toxicity studies to high-throughput screening (HTS) paradigms and risk assessment based on in vitro and in silico testing requires utilizing toxicity pathway information to distinguish adverse outcomes from recoverable adaptive events. Little work has focused on oxidative stresses in human airway for the purposes of predicting adverse responses. We hypothesize that early gene expression-mediated molecular changes could be used to delineate adaptive and adverse responses to environmentally-based perturbations. Here, we examined cellular responses of the tracheobronchial airway to zinc (Zn) exposure, a model oxidant. Airway derived BEAS-2B cells exposed to 210 M Zn2+ elicited concentration- and time-dependent cytotoxicity. Normal, adaptive, and cytotoxic Zn2+ exposure conditions were determined with traditional apical endpoints, and differences in global gene expression around the tipping point of the responses were used to delineate underlying molecular mechanisms. Bioinformatic analyses of differentially expressed genes indicate early enrichment of stress signaling pathways, including those mediated by the transcription factors p53 and NRF2. After 4 h, 154 genes were differentially expressed (p <0.01) between the adaptive and cytotoxic Zn2+ concentrations. Nearly 40% of the biomarker genes were related to the p53 signaling pathway with 30 genes identified as likely direct targets using a database of p53 ChIP-seq studies. Despite similar p53 activation profiles, these data revealed widespread dampening of p53 and NRF2-related genes as early as 4 h after exposure at higher, unrecoverable Zn2+ exposures. Thus, in our model early increased activation of stress response pathways indicated a recoverable adaptive event. Overall, this study highlights the importance of characterizing molecular mechanisms around the tipping point of adverse responses to better inform HTS paradigms.
Developing a Gene Biomarker at the Tipping Point of Adaptive and Adverse Responses in Human Bronchial Epithelial Cells.
Cell line, Time
View SamplesUse of archival resources has been limited to date by inconsistent methods for genomic profiling of degraded RNA from formalin-fixed paraffin-embedded (FFPE) samples. RNA-seq offers a novel way to address this problem. In this study we evaluated transcriptomic dose responses using RNA-seq in paired FFPE and frozen (FROZ) samples from two archival studies in mice, one recent (<2 years old) and the other older (>20 years old). Experimental treatments included di(2-ethylhexyl)phthalate (DEHP) and dichloroacetic acid (DCA) for the <2 and >20 year-old studies, respectively. Total RNA was ribodepleted and sequenced using the Illumina HiSeq platform. In the recent study, FFPE samples showed high concordance in total reads (98% vs FROZ), fold-change values of differentially expressed genes (DEGs) (R2 = 0.99), highly enriched target pathways (90% overlap with FROZ), and benchmark dose estimates for preselected target genes (-2% overall vs FROZ). In contrast, RNA-seq data from older FFPE samples had lower total reads (70% vs FROZ) and poor concordance in global DEGs and pathways. Despite a 99% loss of counts, dose responses were still evident for target genes in FFPE samples and positively correlated with paired FROZ samples. These findings highlight potential variability in the quality of RNA-seq data from FFPE samples. More recent FFPE samples were highly similar to FROZ samples in sequencing quality metrics, DEG profiles, and dose-response parameters, while further methods development is needed for older or lower-quality FFPE samples. This work should help broaden the use of archival resources in both chemical safety and translational science. Overall design: Trancriptomic profiles obtained using from paired frozen (FROZ) and formalin-fixed paraffin-embedded (FFPE) liver samples collected in 2013 for the DEHP study (n=16 FROZ, n=16 FFPE, with four dose groups at 0, 1500, 3000, and 6000 ppm DEHP, n=4 per dose group) and 1994 for the DCA study (n=24 FROZ, n=24 FFPE, with four dose groups at 0, 1.0, 2.0, and 3.5 g/L DCA, n=6 per dose group) using Illumina HiSeq platform.
Editor's Highlight: Dose-Response Analysis of RNA-Seq Profiles in Archival Formalin-Fixed Paraffin-Embedded Samples.
Sex, Age, Specimen part, Cell line, Treatment, Subject
View SamplesPrior microarray studies of smokers at high risk for lung cancer have demonstrated that heterogeneity in bronchial airway epithelial cell gene expression response to smoking can serve as an early diagnostic biomarker for lung cancer. This study examines the relationship between gene expression variation and genetic variation in a central molecular pathway (NRF2-mediated antioxidant response) associated with smoking exposure and lung cancer. We assessed global gene expression in histologically normal airway epithelial cells obtained at bronchoscopy from smokers who developed lung cancer (SC, n=20), smokers without lung cancer (SNC, n=24), and never smokers (NS, n=8). Functional enrichment showed that the NRF2-mediated antioxidant response pathway differed significantly among these groups.
Genetic variation and antioxidant response gene expression in the bronchial airway epithelium of smokers at risk for lung cancer.
Sex, Age, Specimen part, Race, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Protein disulfide isomerase inhibition synergistically enhances the efficacy of sorafenib for hepatocellular carcinoma.
Specimen part, Cell line
View SamplesSorafenib is the only approved targeted drug for hepatocellular carcinoma (HCC), but its effect on patients survival gain is limited and varies over a wide range depending on patho-genetic conditions. Thus, enhancing the efficacy of sorafenib and finding a reliable predictive biomarker are crucuial to achieve efficient control of HCCs. In this study, we employed a systems approach by combining transcriptome analysis of the mRNA changes in HCC cell lines in response to sorafenib with network analysis to investigate the action and resistance mechanism of sorafenib. Gene ontology and gene set analysis revealed that proteotoxic stress and apoptosis modules are activated in the presence of sorafenib. Further analysis of the endoplasmic reticulum (ER) stress network model combined with in vitro experiments showed that introducing an additional stress by treating the orally active protein disulfide isomerase (PDI) inhibitor (PACMA 31) can synergistically increase the efficacy of sorafenib in vitro and in vivo, which was confirmed using a mouse xenograft model. We also found that HCC patients with high PDI expression show resistance to sorafenib and poor clinical outcomes, compared to the low PDI expression group. These results suggest that PDI is a promising therapeutic target for enhancing the efficacy of sorafenib and can also be a biomarker for predicting sorafenib responsiveness.
Protein disulfide isomerase inhibition synergistically enhances the efficacy of sorafenib for hepatocellular carcinoma.
Specimen part, Cell line
View SamplesSorafenib is the only approved targeted drug for hepatocellular carcinoma (HCC), but its effect on patients survival gain is limited and varies over a wide range depending on patho-genetic conditions. Thus, enhancing the efficacy of sorafenib and finding a reliable predictive biomarker are crucuial to achieve efficient control of HCCs. In this study, we employed a systems approach by combining transcriptome analysis of the mRNA changes in HCC cell lines in response to sorafenib with network analysis to investigate the action and resistance mechanism of sorafenib. Gene ontology and gene set analysis revealed that proteotoxic stress and apoptosis modules are activated in the presence of sorafenib. Further analysis of the endoplasmic reticulum (ER) stress network model combined with in vitro experiments showed that introducing an additional stress by treating the orally active protein disulfide isomerase (PDI) inhibitor (PACMA 31) can synergistically increase the efficacy of sorafenib in vitro and in vivo, which was confirmed using a mouse xenograft model. We also found that HCC patients with high PDI expression show resistance to sorafenib and poor clinical outcomes, compared to the low PDI expression group. These results suggest that PDI is a promising therapeutic target for enhancing the efficacy of sorafenib and can also be a biomarker for predicting sorafenib responsiveness.
Protein disulfide isomerase inhibition synergistically enhances the efficacy of sorafenib for hepatocellular carcinoma.
Specimen part, Cell line
View SamplesSorafenib is the only approved targeted drug for hepatocellular carcinoma (HCC), but its effect on patients survival gain is limited and varies over a wide range depending on patho-genetic conditions. Thus, enhancing the efficacy of sorafenib and finding a reliable predictive biomarker are crucuial to achieve efficient control of HCCs. In this study, we employed a systems approach by combining transcriptome analysis of the mRNA changes in HCC cell lines in response to sorafenib with network analysis to investigate the action and resistance mechanism of sorafenib. Gene ontology and gene set analysis revealed that proteotoxic stress and apoptosis modules are activated in the presence of sorafenib. Further analysis of the endoplasmic reticulum (ER) stress network model combined with in vitro experiments showed that introducing an additional stress by treating the orally active protein disulfide isomerase (PDI) inhibitor (PACMA 31) can synergistically increase the efficacy of sorafenib in vitro and in vivo, which was confirmed using a mouse xenograft model. We also found that HCC patients with high PDI expression show resistance to sorafenib and poor clinical outcomes, compared to the low PDI expression group. These results suggest that PDI is a promising therapeutic target for enhancing the efficacy of sorafenib and can also be a biomarker for predicting sorafenib responsiveness.
Protein disulfide isomerase inhibition synergistically enhances the efficacy of sorafenib for hepatocellular carcinoma.
Specimen part, Cell line
View Samples1. To identify potential effectors responsible for anti-tumorigenesis by targeting PLD1, we performed microarray in two Wnt-relevant colon cancer cells and analyzed transcriptional profile of genes that were differently expressed by inhibition and knockdown of PLD1
Targeting phospholipase D1 attenuates intestinal tumorigenesis by controlling β-catenin signaling in cancer-initiating cells.
Specimen part, Cell line
View SamplesMemory stabilization after learning requires transcriptional and translational regulations in the brain, yet the temporal molecular changes following learning have not been explored at the genomic scale. We here employed ribosome profiling and RNA sequencing to quantify the translational status and transcript levels in mouse hippocampus following contextual fear conditioning. We identified 104 genes that are dynamically regulated. Intriguingly, our analysis revealed novel repressive regulations in the hippocampus: translational suppression of ribosomal protein-coding genes at basal state; learning-induced early translational repression of specific genes; and late persistent suppression of a subset of genes via inhibition of ESR1/ERa signaling. Further behavioral analyses revealed that Nrsn1, one of the newly identified genes undergoing rapid translational repression, can act as a memory suppressor gene. This study unveils the yet unappreciated importance of gene repression mechanisms in memory formation. Overall design: The application of ribosome profiling and RNA-seq techniques to mouse hippocampi tissues after contextual fear conditioning and to mouse hippocampal primary cultures. Mouse ESCs were also examined.
Multiple repressive mechanisms in the hippocampus during memory formation.
No sample metadata fields
View Samples