Primary human hepatocytes (PHH) are a main instrument in drug metabolism research and in the prediction of drug-induced phase I/II enzyme induction in humans. The HepG2 liver-derived cell line is commonly used as a surrogate for human hepatocytes, but their use in ADME and toxicity studies can be limited because of lowered basal levels of metabolizing enzymes. Despite their widespread use, the transcriptome of HepG2 cells compared to PHH is not well characterized. In this study, microarray analysis was conducted to ascertain the differences and similarities in mRNA expression between HepG2 cells and human hepatocytes before and after exposure to a panel of fluoroquinolone compounds. Comparison of the nave HepG2 cell and PHH transcriptomes revealed a substantial number of basal gene expression differences. When HepG2 cells were dosed with a series of fluoroquinolones, trovafloxacin, which has been associated with human idiosyncratic hepatotoxicity, induced substantially more gene expression changes than the other quinolones, similar to previous observations with PHH. While TVX-treatment resulted in many gene expression differences between HepG2 cells and PHH, there were also a number of TVX-induced commonalities, including genes involved in RNA processing and mitochondrial function. Taken together, these results provide insight for interpretation of results from drug metabolism and toxicity studies conducted with HepG2 cells in lieu of PHH, and could provide further insight into the mechanistic evaluation of TVX-induced hepatotoxicity.
Trovafloxacin-induced gene expression changes in liver-derived in vitro systems: comparison of primary human hepatocytes to HepG2 cells.
Sex, Specimen part
View SamplesIdentifying the early gene program induced by GnRH would help understand how GnRH-activated signaling pathways modulate gonadotrope secretory response. We previously analyzed GnRH-induced early genes in LbT2 cells, however these lack GnRH self-potentiation, a physiological attribute of gonadotropes. To minimize cellular heterogeneity, rat primary pituitary cultures were enriched for gonadotropes by 40-60% using a sedimentation gradient. Given the limited number of gonadotropes, RNA was amplified prior to microarray analysis. Thirty-three genes were up-regulated 40 minutes after GnRH stimulation. Real-time PCR confirmed regulation of several transcripts including fosB, c-fos, egr-2 and rap1b, a small GTPase and member of the Ras family. GnRH stimulated rap1b gene expression in gonadotropes, measured by a sensitive single cell assay. Immunocytochemistry revealed increased Rap1 protein in GnRH-stimulated gonadotropes. These data establish rap1b as a novel gene rapidly induced by GnRH and a candidate to modulate gonadotropin secretion in rat gonadotropes.
Optimized amplification and single-cell analysis identify GnRH-mediated activation of Rap1b in primary rat gonadotropes.
Sex, Specimen part
View SamplesE. coli MG155 cells were grown at different grwoth rates in mixed substrate culture. To facilitate different metaoblic status, cells adjust substrate consumption behavior which must be reflected in the gene expression profiles of metablism network. The metabolism network including the substrate transporter systems is our study focus.
Carbon catabolite repression correlates with the maintenance of near invariant molecular crowding in proliferating E. coli cells.
Treatment
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AhR activation underlies the CYP1A autoinduction by A-998679 in rats.
Sex, Specimen part, Treatment
View SamplesMale Sprague-Dawley rats [Crl:CD(SD)IGS BR], weighing ~250 g at study initiation were obtained from Charles River Laboratories, Inc. (Wilmington, MA). Rats were housed singly in ventilated, stainless steel, wire-bottom hanging cages and fed non-certified Rodent Chow (Harlan Labs, Madison, WI) and water ad libitum and acclimated for at least 5 days after arrival. Rats were randomly assigned to various treatment groups (3 rats/group) and were dosed once daily by oral gavage with vehicle (0.2% hydroxypropylmethylcellulose at a dose volume of 10 ml/kg) or with 30, 100, or 200 mg/kg of A-998679. All rats were fasted overnight after their last dose, weighed and sacrificed under isoflurane anesthesia. Liver and small intestine (jejunum) were flash frozen in liquid nitrogen and stored at 80C until processing for gene expression profiling on the Affymetrix platform.
AhR activation underlies the CYP1A autoinduction by A-998679 in rats.
Sex, Specimen part
View SamplesMale Sprague-Dawley rats [Crl:CD(SD)IGS BR], weighing ~250 g at study initiation were obtained from Charles River Laboratories, Inc. (Wilmington, MA). Rats were housed singly in ventilated, stainless steel, wire-bottom hanging cages and fed non-certified Rodent Chow (Harlan Labs, Madison, WI) and water ad libitum and acclimated for at least 5 days after arrival. Rats were randomly assigned to various treatment groups (3 rats/group) and were dosed once daily by oral gavage with vehicle (0.2% hydroxypropylmethylcellulose at a dose volume of 10 ml/kg) or with 30, 100, or 200 mg/kg of A-998679. All rats were fasted overnight after their last dose, weighed and sacrificed under isoflurane anesthesia. Liver and small intestine (jejunum) were flash frozen in liquid nitrogen and stored at 80C until processing for gene expression profiling on the Affymetrix platform.
AhR activation underlies the CYP1A autoinduction by A-998679 in rats.
Sex, Specimen part, Treatment
View SamplesInnate immunity is fundamental to recognition and clearance of bacterial infection. The relevant cells and molecules that orchestrate an effective response, however, remain incompletely understood. Here we describe a previously unknown population of B cells, which we have named innate response activator (IRA) B cells that recognize bacteria directly through TLR-4-MyD88 and protect against polymicrobial sepsis.
Innate response activator B cells protect against microbial sepsis.
Sex, Specimen part, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Resistance to CDK2 inhibitors is associated with selection of polyploid cells in CCNE1-amplified ovarian cancer.
Specimen part
View SamplesCyclin E1 (CCNE1) is amplified in various tumor types including high-grade serous ovarian cancer where it is associated with poor clinical outcome. We have demonstrate that suppression of the Cyclin E1 partner kinase, CDK2, induces apoptosis in a CCNE1 amplicon-dependent manner. Little is known of mechanisms of resistance to CDK inhibitors. We therefore generated OVCAR-3 sublines with reduced sensitivity to CDK2 inhibitors and profiled by gene expression microarrays.
Resistance to CDK2 inhibitors is associated with selection of polyploid cells in CCNE1-amplified ovarian cancer.
Specimen part
View SamplesInduced pluripotent stem cell-derived human hepatocyte-like cells (iHeps) could provide a powerful tool for studying the mechanisms underlying human liver development and disease, testing the efficacy and safety of pharmaceuticals across different patients (i.e. personalized medicine), and enabling cell-based therapies in the clinic. However, current in vitro protocols that rely upon growth factors and extracellular matrices (ECM) alone yield iHeps with low levels of liver functions relative to adult primary human hepatocytes (PHHs). Moreover, these low hepatic functions in iHeps are difficult to maintain for prolonged times (weeks to months) in culture. Here, we engineered a micropatterned co-culture (iMPCC) platform in a multi-well format that, in contrast to conventional confluent cultures, significantly enhanced the functional maturation and longevity of iHeps in culture for 4 weeks in vitro when benchmarked against multiple donors of PHHs. In particular, iHeps were micropatterned onto collagen-coated domains of empirically optimized dimensions, surrounded by 3T3-J2 murine embryonic fibroblasts, and then sandwiched with a thin layer of ECM gel (Matrigel). We assessed iHep maturity via global gene expression profiles, hepatic polarity, secretion of albumin and urea, basal CYP450 activities, phase-II conjugation, drug-mediated CYP450 induction, and drug-induced hepatotoxicity. Conclusion: Controlling both homotypic interactions between iHeps and heterotypic interactions with stromal fibroblasts significantly matures iHep functions and maintains them for several weeks in culture. In the future, iMPCCs could prove useful for drug screening, studying molecular mechanisms underlying iHep differentiation, modeling liver diseases, and integration into human-on-a-chip systems being designed to assess multi-organ responses to compounds.
Enhancing the functional maturity of induced pluripotent stem cell-derived human hepatocytes by controlled presentation of cell-cell interactions in vitro.
Specimen part, Subject
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