TXB-001, a newly-developed polymer-conjugated anthracycline: Significantly lower adverse effects in animal models of alopecia and hand-foot syndrome.

Anthracycline anti-cancer drugs have been widely used in the treatment of several cancers; however, their use is limited by adverse effects (AEs). Alopecia is a common AE that is minimally invasive, but adversely affects mental health and reduces quality of life (QoL). Hand-foot syndrome (HFS) is a dose-limiting AE of DOXIL, a liposomal formulation of doxorubicin (DOX). Although it is not a life-threatening condition, HFS affects function and reduces QoL. TXB-001 is a new candidate polymer-conjugated anthracycline anti-cancer drug, and modified and optimized polymerized pirarubicin (THP), known as P-THP, is expected to have low toxicity and high efficacy. The anti-cancer effects of TXB-001 were examined using the 4T1 mouse model. An alopecia mouse model and HFS rat model were used to evaluate the alopecia- and HFS-inducing effects of TXB-001 and compare their severity with existing anthracycline anti-cancer drugs. A pharmacokinetic analysis of plasma as well as chest, palmar, and plantar skin samples after the single intravenous administration of DOXIL and TXB-001 to rats was also performed. The results obtained revealed that TXB-001 exerted similar anti-cancer effects to those of DOXIL in mice, weaker alopecia-inducing effects than DOX, DOXIL, and THP in mice, and no or markedly weaker HFS-like changes than DOXIL, which induced significant histopathological changes. The results of the pharmacokinetic analysis showed the accumulation of DOXIL, but not TXB-001, in skin, particularly palmar and plantar skin samples, and these differences were considered to contribute to their HFS-inducing effects.

Lysosomal trapping of 4-dimethylamino-1-{3-(1-methyl-1H-imidazole-2-yl)propanoyl}piperidine, a hydrophilic and weakly basic amine, in human aortic vascular smooth muscle cells.

Some weakly basic compounds lead to cell death accompanied by cellular vacuolation. The novel analgesic agent, 4-dimethylamino-1-{3-(1-methyl-1H-imidazole-2-yl)propanoyl}piperidine (DMIP), is a hydrophilic and weakly basic compound that induces vacuolation in the vascular smooth muscle cells in dogs. Here, we investigated the vacuolation mechanism and the potential cytotoxicity of DMIP using human aortic vascular smooth muscle cells. When cells were treated with DMIP (0.1, 0.3, and 1 mM) for 6, 24, and 48 h, clear cytoplasmic vacuolation was observed at 1 mM after 24 and 48 h, along with an increase in the intracellular DMIP concentration. The vacuolation and intracellular DMIP were markedly reduced by bafilomycin A1, a vacuolar H+-ATPase inhibitor. The late endosome marker Rab7 and lysosome marker LAMP-2 were highly expressed but the early endosome marker Rab5 and autophagosome marker LC3 were not expressed specifically on the vacuolar membranes. These results suggested that the most vacuoles were enlarged late endosomes/lysosomes, resulting from the accumulation of DMIP by ion trapping. Moreover, DMIP did not affect lysosomal membrane integrity and was less cytotoxic than chloroquine, an inducer of phospholipidosis. The current study provides further insight into the mechanisms of vacuolation and lysosomal trapping induced by the hydrophilic and weakly basic amine DMIP.

Spontaneous hemangioendothelial cell hyperplasia of the heart in a young ICR mouse.

Spontaneous nonneoplastic proliferative lesions of the cardiac hemangioendothelium are extremely rare in humans and animals. Here, we describe a spontaneous hemangioendothelial cell hyperplasia in the heart of a 9-week-old male ICR mouse. The lesion was observed focally in the interventricular septum, with no compression of the surrounding tissues. In the lesion, a single layer of hemangioendothelial cells that had a polygonal shape with enlarged nuclei and plump cytoplasm closely lined surrounding widened capillary vascular spaces and cardiac muscles. There was little cellular atypia, and there were no multilayered endothelial cells. Immunohistochemical staining revealed that these cells were partly positive for factor VIII and CD31, hemangioendothelial cell markers, and negative for Ki-67. These features were consistent with those in aged female B6C3F1 mice in the only report in mice of spontaneous cardiac hemangioendothelial cell hyperplasia. Therefore, this is the first report of spontaneous hemangioendothelial cell hyperplasia in the heart of a young mouse.

Cytoplasmic Vacuolation and Tapetal Changes Induced by a Novel Analgesic Agent in Beagle Dogs.

Drug-induced unique cytoplasmic vacuolation was found in the subchronic oral toxicity study of 4-dimethylamino-1-{3-(1-methyl-1H-imidazole-2-yl)propanoyl}piperidine (DMIP), a potential therapeutic agent for neuropathic pain, in beagle dogs. In the first study, DMIP was administered at a dose of 250, 500, or 1,000 mg/kg/day once daily for 14 days. Discoloration of tapetum lucidum accompanied by tapetal swelling was observed at ≥250 mg/kg/day. The tapetal swelling was correlated to the light microscopic observation of cytoplasmic vacuolation in tapetal cells, and similar vacuolation was observed in several other tissues, including the coronary artery and aortal arch, in a dose-dependent manner. Immunohistochemistry for lysosomal-associated membrane protein 2 indicated that the vacuoles were enlarged lysosomes. However, the nature of these vacuoles was different from that of phospholipidosis because no lamellar bodies were observed. In the second study, DMIP was administered at a dose of 10, 50, or 250 mg/kg/day once daily for 14 days followed by a 14-day recovery period. Tapetal changes and systemic vacuolation were not observed at ≤50 mg/kg/day, and vacuolation observed at 250 mg/kg/day was reversible. A few reports have described the enlargement of lysosomes not attributable to phospholipid accumulation. Our findings provide further information about the toxicological implications of drug-induced lysosomal swelling.

Chemical Activation of the Constitutive Androstane Receptor Leads to Activation of Oxidant-Induced Nrf2.

Exposure to environmentally relevant chemicals that activate the xenobiotic receptors aryl hydrocarbon receptor (AhR), constitutive androstane receptor (CAR), and peroxisome proliferator-activated receptor alpha (PPARα) in rodent test systems often leads to increases in oxidative stress (OS) that contributes to liver cancer induction. We hypothesized that activation of the oxidant-induced transcription factor Nrf2 could be used as a surrogate endpoint for increases in OS. We examined the relationships between activation of xenobiotic receptors and Nrf2 using previously characterized gene expression biomarkers that accurately predict modulation. Using a correlation approach (Running Fisher Test), the biomarkers were compared with microarray profiles in a mouse liver gene expression compendium. Out of the 163 chemicals examined, 47% from 53 studies activated Nrf2. We found consistent coupling between CAR and Nrf2 activation. Out of the 41 chemicals from 32 studies that activated CAR, 90% also activated Nrf2. CAR was activated earlier and at lower doses than Nrf2, indicating CAR activation preceded Nrf2 activation. Nrf2 activation by 2 CAR activators was abolished in CAR-null mice. We hypothesized that Nrf2 is activated by reactive oxygen species from the increased activity of enzymes encoded by Cyp2b family members. However, Nrf2 was similarly activated in the livers of both TCPOBOP-treated wild-type and Cyp2b9/10/13-null mice. This study provides evidence that Nrf2 activation (1) often occurs after exposure to xenobiotic chemicals, (2) is tightly linked to activation of CAR, and (3) does not require induction of 3 Cyp2b genes secondary to CAR activation.

Activation of Nrf2 in the liver is associated with stress resistance mediated by suppression of the growth hormone-regulated STAT5b transcription factor.

The transcription factor Nrf2 (encoded by Nfe2l2) induces expression of numerous detoxifying and antioxidant genes in response to oxidative stress. The cytoplasmic protein Keap1 interacts with and represses Nrf2 function. Computational approaches were developed to identify factors that modulate Nrf2 in a mouse liver gene expression compendium. Forty-eight Nrf2 biomarker genes were identified using profiles from the livers of mice in which Nrf2 was activated genetically in Keap1-null mice or chemically by a potent activator of Nrf2 signaling. The rank-based Running Fisher statistical test was used to determine the correlation between the Nrf2 biomarker genes and a test set of 81 profiles with known Nrf2 activation status demonstrating a balanced accuracy of 96%. For a large number of factors examined in the compendium, we found consistent relationships between activation of Nrf2 and feminization of the liver transcriptome through suppression of the male-specific growth hormone (GH)-regulated transcription factor STAT5b. The livers of female mice exhibited higher Nrf2 activation than male mice in untreated or chemical-treated conditions. In male mice, Nrf2 was activated by treatment with ethinyl estradiol, whereas in female mice, Nrf2 was suppressed by treatment with testosterone. Nrf2 was activated in 5 models of disrupted GH signaling containing mutations in Pit1, Prop1, Ghrh, Ghrhr, and Ghr. Out of 59 chemical treatments that activated Nrf2, 36 exhibited STAT5b suppression in the male liver. The Nrf2-STAT5b coupling was absent in in vitro comparisons of chemical treatments. Treatment of male and female mice with 11 chemicals that induce oxidative stress led to activation of Nrf2 to greater extents in females than males. The enhanced basal and inducible levels of Nrf2 activation in females relative to males provides a molecular explanation for the greater resistance often seen in females vs. males to age-dependent diseases and chemical-induced toxicity.

Gene expression profiles in auricle skin as a possible additional endpoint for determination of sensitizers: A multi-endpoint evaluation of the local lymph node assay.

The murine local lymph node assay (LLNA) is widely used to test chemicals to induce skin sensitization. Exposure of mouse auricle skin to a sensitizer results in proliferation of local lymph node T cells, which has been measured by in vivo incorporation of H3-methyl thymidine or 5-bromo-2'-deoxyuridine (BrdU). The stimulation index (SI), the ratio of the mean proliferation in each treated group to that in the concurrent vehicle control group, is frequently used as a regulatory-authorized endpoint for LLNA. However, some non-sensitizing irritants, such as sodium dodecyl sulfate (SDS) or methyl salicylate (MS), have been reported as false-positives by this endpoint. In search of a potential endpoint to enhance the specificity of existing endpoints, we evaluated 3 contact sensitizers; (hexyl cinnamic aldehyde [HCA], oxazolone [OXA], and 2,4-dinitrochlorobenzene [DNCB]), 1 respiratory sensitizer (toluene 2,4-diisocyanate [TDI]), and 2 non-sensitizing irritants (MS and SDS) by several endpoints in LLNA. Each test substance was applied to both ears of female CBA/Ca mice daily for 3 consecutive days. The ears and auricle lymph node cells were analyzed on day 5 for endpoints including the SI value, lymph node cell count, cytokine release from lymph node cells, and histopathological changes and gene expression profiles in auricle skin. The SI values indicated that all the test substances induced significant proliferation of lymph node cells. The lymph node cell counts showed no significant changes by the non-sensitizers assessed. The inflammatory findings of histopathology were similar among the auricle skins treated by sensitizers and irritants. Gene expression profiles of cytokines IFN-γ, IL-4, and IL-17 in auricle skin were similar to the cytokine release profiles in draining lymph node cells. In addition, the gene expression of the chemokine CXCL1 and/or CXCL2 showed that it has the potential to discriminate sensitizers and non-sensitizing irritants. Our results suggest that multi-endpoint analysis in the LLNA leads to a better determination of the sensitizing potential of test substances. We also show that the gene expression of CXCL1 and/or CXCL2, which is involved in elicitation of contact hypersensitivity (CHS), can be a possible additional endpoint for discrimination of sensitizing compounds in LLNA.

Identification of Transporters Involved in Beraprost Sodium Transport In Vitro.

BACKGROUND AND OBJECTIVE: Beraprost sodium (BPS) is a chemically stable and orally active prostacyclin analog that is used in the treatment of chronic arterial occlusive disease since 1992 and primary pulmonary hypertension since 1999 in Japan. Multiple-drug therapy is common in clinical practice, and BPS is co-administered with other drugs. Membrane transporters are known to markedly affect pharmacokinetics, safety and efficacy, and many transporter-based drug-drug interactions have been recently reported. However, information on the transporters involved in the pharmacokinetics of BPS is limited. METHODS: First of all, we have examined 11 transporters, ABCB1 (P-glycoprotein: P-gp), ABCG2 (breast cancer resistance protein: BCRP), SLC22A6 (organic anion transporter 1: OAT1), SLC22A8 (organic anion transporter 3: OAT3), SLCO1B1 (organic anion transporting polypeptide 1B1: OATP1B1), SLCO1B3 (organic anion transporting polypeptide 1B3: OATP1B3), SLCO2B1 (organic anion transporting polypeptide 2B1: OATP2B1), SLC22A1 (organic cation transporter 1: OCT1), SLC22A2 (organic cation transporter 2: OCT2), ABCB11 (bile-salt export pump: BSEP), and ABCC2 (multidrug resistance associated protein 2: MRP2) to clarify which of them would be candidates that might recognize BPS as their substrate in transporter-expressing LLC-PK1, S2, and HEK293 cells as well as in membrane vesicles. Furthermore, we determined whether the transport of BPS was inhibited by the typical inhibitors of each transporter, i.e., verapamil for P-gp, Ko143 for BCRP, probenecid for OAT3, rifampicin for OATP1B1 and OATP1B3, cyclosporine for BSEP, and sulfobromophthalein (BSP) for MRP2. RESULTS: The results obtained showed that P-gp, BCRP, OAT3, OATP1B1, OATP1B3, BSEP and MRP2 might be candidates for BPS transporters. From the further evaluation with the typical inhibitors of each transporter, it was confirmed that BPS is a substrate for P-gp, BCRP, OAT3, OATP1B1, OATP1B3 and MRP2, because the typical inhibitor, cyclosporine, had no effects on BPS transport by BSEP. CONCLUSIONS: BPS is a substrate of 6 transporters: P-gp, BCRP, OAT3, OATP1B1, OATP1B3, and MRP2, because their expressing cells and vesicles transported BPS more than in the controls, and BPS transport activities were reduced by the typical inhibitors of tested transporters. Although there are no reports regarding drug-drug interactions between BPS and possible combination drugs expected due to transporters, it may be necessary to notice that that substrates or inhibitors for the 6 mentioned transporters may have effects on pharmacokinetics of BPS when co-administered.

The Pharmacokinetics of Beraprost Sodium Following Single Oral Administration to Subjects With Impaired Kidney Function.

The purpose of the present study was to evaluate the pharmacokinetics of beraprost sodium (BPS) and its active enantiomer, BPS-314d, in Japanese subjects with impaired kidney function. The plasma and urine concentrations of BPS and BPS-314d were measured following the single oral administration of 120 µg of BPS as the sustained-release tablet, TRK-100STP, under fasting conditions to 18 subjects with impaired kidney function (stage 2, 3, and 4 chronic kidney disease [CKD] as categorized by the estimated glomerular filtration rate) and to 6 age-, body weight-, and gender-matched subjects with normal kidney function (stage 1 CKD). The Cmax values (mean ± SD) of BPS in stage 1, 2, 3, and 4 CKD, respectively, were 84.9 ± 22.9, 119.8 ± 36.4, 190.6 ± 137.3, and 240.2 ± 110.5 pg/mL; its AUC0-48h were 978 ± 226, 1252 ± 427, 1862 ± 964, and 1766 ± 806 pg·h/mL, respectively, and its cumulative urinary excretion rates were 0.704 ± 0.351%, 0.638 ± 0.292%, 0.485 ± 0.294%, and 0.159 ± 0.136%. The Cmax values of BPS-314d were 22.4 ± 6.4, 30.8 ± 8.5, 46.7 ± 30.6, and 54.4 ± 25.2 pg/mL, its AUC0-48h were 155 ± 56, 226 ± 67, 341 ± 176, and 329 ± 143 pg·h/mL, and its cumulative urinary excretion rates were 0.428 ± 0.242%, 0.349 ± 0.179%, 0.356 ± 0.270%, and 0.096 ± 0.099%, respectively. Adverse events were reported in 2 subjects with stage 2 CKD and 1 subject with stage 4 CKD. The Cmax and AUC0-48h of BPS and BPS-314d were higher based on the severity of impaired kidney function. No relationship was observed between the incidence of adverse events and the severity, and tolerability was confirmed. We consider that dose adjustment is not necessary, but BPS is more carefully treated in patients with impaired kidney function.

Evaluation of red blood cell Pig-a assay and PIGRET assay in rats using chlorambucil.

The Pig-a assay is a novel method to assess the in vivo mutagenicity of compounds, and it is expected to be useful for the detection of genotoxicity. In this study, to assess the performance of the Pig-a assay targeting red blood cells (RBCs; RBC Pig-a assay) and reticulocytes (RETs; PIGRET assay), chlorambucil, which is a genotoxicant, was orally administered to male rats once at 10, 20 and 40mg/kg on Day 1, and the mutant frequencies (MFs) of RBCs and RETs were examined periodically. In the RBC Pig-a assay, significant increases in MFs were observed at 40mg/kg on Day 15 and at 20mg/kg or higher on Day 29. In the PIGRET assay, MFs increased significantly at all dose levels on Day 8 and only at 20mg/kg on Day 15, but there was no increase in MFs in the treatment groups on Day 29. In conclusion, the RBC Pig-a assay and PIGRET assay in rats have sufficient sensitivity to detect the mutagenicity of chlorambucil, and the PIGRET assay could detect its mutagenicity earlier and at a lower dose than the RBC Pig-a assay.

Correction: Chemical and Hormonal Effects on STAT5b- Dependent Sexual Dimorphism of the Liver Transcriptome.

[This corrects the article DOI: 10.1371/journal.pone.0150284.].

Chemical and Hormonal Effects on STAT5b-Dependent Sexual Dimorphism of the Liver Transcriptome.

The growth hormone (GH)-activated transcription factor signal transducer and activator of transcription 5b (STAT5b) is a key regulator of sexually dimorphic gene expression in the liver. Suppression of hepatic STAT5b signaling is associated with lipid metabolic dysfunction leading to steatosis and liver cancer. In the companion publication, a STAT5b biomarker gene set was identified and used in a rank-based test to predict both increases and decreases in liver STAT5b activation status/function with high (≥ 97%) accuracy. Here, this computational approach was used to identify chemicals and hormones that activate (masculinize) or suppress (feminize) STAT5b function in a large, annotated mouse liver and primary hepatocyte gene expression compendium. Exposure to dihydrotestosterone and thyroid hormone caused liver masculinization, whereas glucocorticoids, fibroblast growth factor 15, and angiotensin II caused liver feminization. In mouse models of diabetes and obesity, liver feminization was consistently observed and was at least partially reversed by leptin or resveratrol exposure. Chemical-induced feminization of male mouse liver gene expression profiles was a relatively frequent phenomenon: of 156 gene expression biosets from chemically-treated male mice, 29% showed feminization of liver STAT5b function, while <1% showed masculinization. Most (93%) of the biosets that exhibited feminization of male liver were also associated with activation of one or more xenobiotic-responsive receptors, most commonly constitutive activated receptor (CAR) or peroxisome proliferator-activated receptor alpha (PPARα). Feminization was consistently associated with increased expression of peroxisome proliferator-activated receptor gamma (Pparg) but not other lipogenic transcription factors linked to steatosis. GH-activated STAT5b signaling in mouse liver is thus commonly altered by diverse chemicals, and provides a linkage between chemical exposure and dysregulated gene expression associated with adverse effects on the liver.

Disruption of STAT5b-Regulated Sexual Dimorphism of the Liver Transcriptome by Diverse Factors Is a Common Event.

Signal transducer and activator of transcription 5b (STAT5b) is a growth hormone (GH)-activated transcription factor and a master regulator of sexually dimorphic gene expression in the liver. Disruption of the GH hypothalamo-pituitary-liver axis controlling STAT5b activation can lead to metabolic dysregulation, steatosis, and liver cancer. Computational approaches were developed to identify factors that disrupt STAT5b function in a mouse liver gene expression compendium. A biomarker comprised of 144 STAT5b-dependent genes was derived using comparisons between wild-type male and wild-type female mice and between STAT5b-null and wild-type mice. Correlations between the STAT5b biomarker gene set and a test set comprised of expression datasets (biosets) with known effects on STAT5b function were evaluated using a rank-based test (the Running Fisher algorithm). Using a similarity p-value ≤ 10(-4), the test achieved a balanced accuracy of 99% and 97% for detection of STAT5b activation or STAT5b suppression, respectively. The STAT5b biomarker gene set was then used to identify factors that activate (masculinize) or suppress (feminize) STAT5b function in an annotated mouse liver and primary hepatocyte gene expression compendium of ~1,850 datasets. Disruption of GH-regulated STAT5b is a common phenomenon in liver in vivo, with 5% and 29% of the male datasets, and 11% and 13% of the female datasets, associated with masculinization or feminization, respectively. As expected, liver STAT5b activation/masculinization occurred at puberty and suppression/feminization occurred during aging and in mutant mice with defects in GH signaling. A total of 70 genes were identified that have effects on STAT5b activation in genetic models in which the gene was inactivated or overexpressed. Other factors that affected liver STAT5b function were shown to include fasting, caloric restriction and infections. Together, these findings identify diverse factors that perturb the hypothalamo-pituitary-liver GH axis and disrupt GH-dependent STAT5b activation in mouse liver.

The Effects of a Selective CK2 Inhibitor on Anti-glomerular Basement Membrane Glomerulonephritis in Rats.

Protein kinase CK2 ("casein kinase II") is a protein serine/threonine kinase that plays critical roles in biological processes such as cell growth, cell cycle progression, and apoptosis. So far, we have identified that one catalytic isozyme of CK2, CK2α, is over-expressed in the kidney during the progression of glomerulonephritis (GN). Moreover, we have shown that in vivo inhibition of CK2 by administration of CK2 inhibitors was effective in the treatment of experimental GN. Hence the development of potent CK2 inhibitors should be considered in therapeutic strategies for GN. In the present study we identified compound 13, a pyrazine derivative, as a potent CK2 inhibitor. By performing enzyme kinetics analysis in vitro, we characterized the inhibition of compound 13 toward each CK2 catalytic isozyme. Furthermore, in vivo, we demonstrated that compound 13 is effective in attenuating proteinuria, decreasing the enhanced level of blood urea nitrogen and serum creatinine, and ameliorating glomerular crescent formation in an experimental GN rat model. On the other hand, cellular apoptosis was detected in the rat testis following administration of compound 13. This study provides clues for new strategies for developing applicable compounds into CK2-targeted GN treatments.

Screening a mouse liver gene expression compendium identifies modulators of the aryl hydrocarbon receptor (AhR).

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the biological and toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), dioxin-like compounds (DLC) as well as some drugs and endogenous tryptophan metabolites. Short-term activation of AhR can lead to hepatocellular steatosis, and chronic activation can lead to liver cancer in mice and rats. Analytical approaches were developed to identify biosets in a genomic database in which AhR activity was altered. A set of 63 genes was identified (the AhR gene expression biomarker) that was dependent on AhR for regulation after exposure to TCDD or benzo[a]pyrene and includes the known AhR targets Cyp1a1 and Cyp1b1. A fold-change rank-based test (Running Fisher's test; p-value ≤ 10(-4)) was used to evaluate the similarity between the AhR biomarker and a test set of 37 and 41 biosets positive or negative, respectively for AhR activation. The test resulted in a balanced accuracy of 95%. The rank-based test was used to identify factors that activate or suppress AhR in an annotated mouse liver/mouse primary hepatocyte gene expression database of ∼ 1850 comparisons. In addition to the expected activation of AhR by TCDD and DLC, AhR was activated by AP20189 and phenformin. AhR was suppressed by phenobarbital and 1,4-Bis[2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP) in a constitutive activated receptor (CAR)-dependent manner and pregnenolone-16α-carbonitrile in a pregnane X receptor (PXR)-dependent manner. Inactivation of individual genes in nullizygous models led to AhR activation (Pxr, Ghrhr, Taf10) or suppression (Ahr, Ilst6st, Hnf1a). This study describes a novel screening strategy for identifying factors in mouse liver that perturb AhR in a gene expression compendium.

Evaluation of the repeated-dose liver micronucleus assay using 2,4-dinitrotoluene: a report of a collaborative study by CSGMT/JEMS.MMS.

The liver micronucleus assay using young adult rats has the potential to detect liver carcinogens by repeated dosing, and could be expected to be integrated into repeated-dose toxicity studies using a hepatocyte isolation method without the traditional in situ collagenase perfusion. In this study, to assess the performance of the repeated-dose liver micronucleus assay, 2,4-dinitrotoluene (DNT), which is a rodent liver carcinogen, was administered orally to male rats at doses of 50, 100 and 200 mg/kg/day once daily for 14 or 28 consecutive days, and the frequencies of micronucleated hepatocytes (MNHEPs) and micronucleated immature erythrocytes (MNIMEs) were examined. Significant increases in the MNHEPs were observed at 50 mg/kg/day or more in the 14-day treatment, and 50 and 100 mg/kg/day in the 28-day treatment. These increases were dependent on both the dose and the number of administrations, which indicates the possibility that the MNHEPs accumulate as a result of repeated dosing. In contrast, no increase in the MNIMEs was observed. In conclusion, the repeated-dose liver micronucleus assay using young adult rats is sufficiently sensitive to detect the genotoxicity of 2,4-DNT at a low dose.

Identification of chemical modulators of the constitutive activated receptor (CAR) in a gene expression compendium.

The nuclear receptor family member constitutive activated receptor (CAR) is activated by structurally diverse drugs and environmentally-relevant chemicals leading to transcriptional regulation of genes involved in xenobiotic metabolism and transport. Chronic activation of CAR increases liver cancer incidence in rodents, whereas suppression of CAR can lead to steatosis and insulin insensitivity. Here, analytical methods were developed to screen for chemical treatments in a gene expression compendium that lead to alteration of CAR activity. A gene expression biomarker signature of 83 CAR-dependent genes was identified using microarray profiles from the livers of wild-type and CAR-null mice after exposure to three structurally-diverse CAR activators (CITCO, phenobarbital, TCPOBOP). A rank-based algorithm (Running Fisher's algorithm (p-value ≤ 10(-4))) was used to evaluate the similarity between the CAR biomarker signature and a test set of 28 and 32 comparisons positive or negative, respectively, for CAR activation; the test resulted in a balanced accuracy of 97%. The biomarker signature was used to identify chemicals that activate or suppress CAR in an annotated mouse liver/primary hepatocyte gene expression database of ~1850 comparisons. CAR was activated by 1) activators of the aryl hydrocarbon receptor (AhR) in wild-type but not AhR-null mice, 2) pregnane X receptor (PXR) activators in wild-type and to lesser extents in PXR-null mice, and 3) activators of PPARα in wild-type and PPARα-null mice. CAR was consistently activated by five conazole fungicides and four perfluorinated compounds. Comparison of effects in wild-type and CAR-null mice showed that the fungicide propiconazole increased liver weight and hepatocyte proliferation in a CAR-dependent manner, whereas the perfluorinated compound perfluorooctanoic acid (PFOA) increased these endpoints in a CAR-independent manner. A number of compounds suppressed CAR coincident with increases in markers of inflammation including acetaminophen, concanavalin A, lipopolysaccharide, and 300 nm silica particles. In conclusion, we have shown that a CAR biomarker signature coupled with a rank-based similarity method accurately predicts CAR activation. This analytical approach, when applied to a gene expression compendium, increased the universe of known chemicals that directly or indirectly activate CAR, highlighting the promiscuous nature of CAR activation and signaling through activation of other xenobiotic-activated receptors.

Identification of modulators of the nuclear receptor peroxisome proliferator-activated receptor α (PPARα) in a mouse liver gene expression compendium.

The nuclear receptor family member peroxisome proliferator-activated receptor α (PPARα) is activated by therapeutic hypolipidemic drugs and environmentally-relevant chemicals to regulate genes involved in lipid transport and catabolism. Chronic activation of PPARα in rodents increases liver cancer incidence, whereas suppression of PPARα activity leads to hepatocellular steatosis. Analytical approaches were developed to identify biosets (i.e., gene expression differences between two conditions) in a genomic database in which PPARα activity was altered. A gene expression signature of 131 PPARα-dependent genes was built using microarray profiles from the livers of wild-type and PPARα-null mice after exposure to three structurally diverse PPARα activators (WY-14,643, fenofibrate and perfluorohexane sulfonate). A fold-change rank-based test (Running Fisher's test (p-value ≤ 10(-4))) was used to evaluate the similarity between the PPARα signature and a test set of 48 and 31 biosets positive or negative, respectively for PPARα activation; the test resulted in a balanced accuracy of 98%. The signature was then used to identify factors that activate or suppress PPARα in an annotated mouse liver/primary hepatocyte gene expression compendium of ~1850 biosets. In addition to the expected activation of PPARα by fibrate drugs, di(2-ethylhexyl) phthalate, and perfluorinated compounds, PPARα was activated by benzofuran, galactosamine, and TCDD and suppressed by hepatotoxins acetaminophen, lipopolysaccharide, silicon dioxide nanoparticles, and trovafloxacin. Additional factors that activate (fasting, caloric restriction) or suppress (infections) PPARα were also identified. This study 1) developed methods useful for future screening of environmental chemicals, 2) identified chemicals that activate or suppress PPARα, and 3) identified factors including diets and infections that modulate PPARα activity and would be hypothesized to affect chemical-induced PPARα activity.

Immunosuppressive potential of bardoxolone methyl using a modified murine local lymph node assay (LLNA).

2-Cyano-3, 12-dioxooleana-1, 9-dien-28-oic acid methyl ester (CDDO-Me; bardoxolone methyl) is one of the synthetic oleanane triterpenoids (SOs). It is known that it is the strongest Nrf2/ARE signaling inducer of SOs and slightly inhibits immune response. Little was known about the immunomodulatory action of CDDO-Me in vivo. We assessed its immunosuppressive potential by using the modified mouse lymph node assay (LLNA) including immunosuppression-related gene expression analysis. In the modified LLNA, CDDO-Me showed a significant decrease in lymph node weight and changes in expressions of the immunosuppression-related genes, Zfp459 and Fmo2. It has been already reported that a decrease in lymph node weight was induced by several types of immunosuppressive chemicals such as calcineurin inhibitors, antimetabolites, steroids, and alkylators. In addition, changes in Zfp459 and Fmo2 expression was reported in response after only treatment of antimetabolites. From these results, CDDO-Me is considered to have an immunosuppressive action and similar mechanism to antimetabolites.

Design and synthesis of novel p38α MAP kinase inhibitors: discovery of pyrazole-benzyl ureas bearing 2-molpholinopyrimidine moiety.

The discovery that pyrazole-benzyl urea derivatives bearing a 2-molpholinopyrimidine moiety are novel p38α inhibitors is described. A comparative view of the binding modes of SB-203580 and BIRB-796 by structural alignment of two X-ray co-crystal structures was utilized to identify this novel series. Modification of the benzyl group led to compound 2b, a highly potent p38α inhibitor. In in vivo studies, 2b inhibited the production of tumor necrosis factor-alpha in lipopolysaccharide-treated mouse in a dose-dependent manner. Furthermore, the results of a 5-day repeated oral dose toxicity study suggest that 2b has low hepatotoxicity.