Project description:The number of legacy chemicals without toxicity reference values combined with the rate of new chemical development are overwhelming the capacity of the traditional risk assessment paradigm. More efficient approaches are needed to quantitatively estimate chemical risks. In this study, rats were dosed orally with multiple doses of six chemicals for 5 days, 2, 4, and 13 weeks. Target organs were analyzed for traditional histological and organ weight changes and transcriptional changes using microarrays. Histological and organ weight changes in this study and the tumor incidences in the original cancer bioassays were analyzed using benchmark dose (BMD) methods to identify noncancer and cancer points-of-departure. The dose-response changes in gene expression were also analyzed using BMD methods and the responses grouped based on signaling pathways. A comparison of transcriptional BMD values for the most sensitive pathway with BMD values for the noncancer and cancer apical endpoints showed a high degree of correlation at all time points. When the analysis included data from an earlier study with 8 additional chemicals, transcriptional BMD values for the most sensitive pathway were significantly correlated with noncancer (r = 0.827, p = 0.0031) and cancer-related (r = 0.940, p = 0.0002) BMD values at 13 weeks. The average ratio of apical-to-transcriptional BMD values was less than two suggesting that for the current chemicals, transcriptional perturbation did not occur at significantly lower doses than apical responses. Based on our results, we propose a practical framework for application of transcriptomic data to chemical risk assessment.
Project description:Mass spectrometry analysis was carried out to investigate the protein expression landscape of RNA-binding proteins (RBPs) during a time-course of spontaneously differentiating human embryonic stem cells (hESCs). Mass spectrometry was performed on whole-cell extracts of differentiating TE03 (I3) hESCs at four time-points (days 0, 23, 39, and 54), each with two biological replicates.
Project description:Environmental chemicals exposure are one of the primary factors for liver toxicity and hepatocarcinoma. Thioacetamide (TAA) is a well-known hepatotoxicant and could be a liver carcinogen in humans.The discovery of early and sensitive biomarkers in liver injury and tumor progression could improve cancer diagnosis, prognosis, and management. In the present study, we studied the dynamic changes in microRNAs (miRNAs) expression and explored the potential mechanistic role of miRNAs in rat liver treated with TAA at multiple doses and time points. Sprague-Dawley rats were administrated with TAA at three doses [low (4.5 mg/kg), middle (15mg/kg) and high (45mg/kg)] and four repeated treatment durations (3-, 7-, 14- and 28-days). Expressions of miRNAs in livers were profiled using next generation sequencing and analyzed. Overall, 330 unique differentially expressed miRNAs (DEMs) were identified in the entire TAA-treatment course. Of these, 129 DEMs were found significantly enriched for the “liver cancer” annotation. These results were further complemented by pathway analysis in which “Molecular Mechanisms of Cancer”, “p53-”, “TGF-β-”, “MAPK-” and “Wnt-signaling” were significantly enriched in most TAA-treatment conditions. Two miRNAs (rno-miR-34a-5p and rno-miR-455-3p) out of 48 DEMs (common across all the treatment conditions) were identified to be early and sensitive biomarkers for TAA-induced hepatocarcinogenicity. Upregulation of rno-miR-34a-5p was further confirmed by qPCR. These findings reveal the critical role of miRNAs in the mechanisms underlying hepatocarcinogenesis and potential application for human risk assessment. Most importantly, rno-miR-34a-5p is the most suitable early and sensitive biomarker for TAA-induced hepatocarcinogenesis due to its consistent elevation during the entire treatment course.
Project description:An increasing number of cancer-associated mutations have been identified. Unfortunately, little therapy today exploits these tumor-specific genetic lesions. Often, the resulting oncoproteins have been intractable to easy manipulation with current small molecule screening approaches. To overcome this impasse, we developed an expression-based approach to small molecule library screening. We applied this platform to the discovery of modulators of the activity of EWS/FLI, the Ewing sarcoma associated oncoprotein. Cytarabine (ARA-C) was identified as the top hit in a small molecule library screen. ARA-C modulates EWS/FLI by decreasing EWS/FLI protein level and has striking effects on cellular viability and transformation in in vitro and in vivo models of Ewing sarcoma. With poor outcomes for patients with relapsed Ewing sarcoma and the well established safety profile of ARA-C, clinical trials testing ARA-C in Ewing sarcoma are warranted. Expression data was created for A673 cells treated with ARA-C and two other compounds used to treat Ewing sarcoma (Puromycin and Doxorubicin) at two doses (EC50 and 2xEC50) and three time points (24 hours, 3 days, and 5 days). Keywords: time course and dose response
Project description:Genome-wide gene expression profiling of hESCs undergoing neuronal differentiation at four distinct time-points. hESCs are differentiated using a novel protocol, and day 0, 7, 13 and 20 were charachterized.
Project description:Genome-wide gene expression profiling of hESCs undergoing neuronal differentiation at four distinct time-points. hESCs are differentiated using a novel protocol, and day 0, 7, 13 and 20 were charachterized.
Project description:With the general adoption of new approach methodologies, the omic-based technologies are of particular importance for chemical hazard characterization owning to the premise that any apical endpoint change indicative of impaired health must be underpinned by some alterations at the omic level. In this work we studied cellular response to caffeine by measuring transcriptomics experiments. The HepG2 cells were treated with 6 doses of caffeine for 24 h. 1 control group was set (0 uM of coumarin). Each group has 3 biological replicates.
Project description:With the general adoption of new approach methodologies, the omic-based technologies are of particular importance for chemical hazard characterization owning to the premise that any apical endpoint change indicative of impaired health must be underpinned by some alterations at the omic level. In this work we studied cellular response to coumarin by measuring transcriptomics experiments. The HepG2 cells were treated with 6 doses of coumarin for 24 h. 1 control group was set (0 uM of coumarin). Each group has 3 biological replicates.
Project description:Genome-wide gene expression profiling of hESCs undergoing neuronal differentiation at four distinct time-points. hESCs are differentiated using a novel protocol, and day 0, 7, 13 and 20 were charachterized.