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At least 1,315 records · Page 73
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DOE OSTI2017

Phase 1 Trial of Everolimus and Radiation Therapy for Salvage Treatment of Biochemical Recurrence in Prostate Cancer Patients Following Prostatectomy

Purpose: In up to half of patients treated with salvage radiation therapy (SRT) for rising prostate-specific antigen levels, a second biochemical recurrence ultimately develops. Phosphatase and tensin homolog inactivation is implicated in prostate cancer progression, and upregulation of the mammalian target of rapamycin pathway can lead to tumor hypoxia and radioresistance. Everolimus is a mammalian target of rapamycin inhibitor with both antitumor and radiosensitizing effects. Methods and Materials: We performed a phase 1 study using a modified 3 + 3 dose-escalation design to evaluate the safety and tolerability of everolimus in combination with standard SRT for the treatment of biochemical recurrence following prostatectomy. After a 2-week run-in period of everolimus daily therapy, patients received prostate bed irradiation with daily cone beam computed tomography localization in 37 fractions of 1.8 Gy each (total dose, 66.6 Gy). Patients were monitored for both acute (≤90 days) and chronic (>90 days) treatment-related toxicities. Results: Eighteen patients received everolimus at dose levels of 5 mg (n=6), 7.5 mg (n=6), or 10 mg (n=6) daily in conjunction with SRT. No dose-limiting toxicities were observed. Common acute treatment-related toxicities included grade 1 or 2 mucositis (55.6%), grade 1 or 2 fatigue (38.9%), grade 1 or 2 rash (61.1%), and grade 1 urinary symptoms (61.1%). A grade 3 acute toxicity occurred in 4 patients (22.2%) (n=1 for rash, anemia, lymphopenia, and neutropenia), and no patients had a chronic toxicity of grade 3 or greater. After a median follow-up time of 17.8 months (range, 1.2-46.0 months), an undetectable prostate-specific antigen nadir was achieved in 9 patients (56.3%) and a second biochemical recurrence developed in 5 patients (31.3%). Conclusions: Everolimus at a dose of ≤10 mg daily appears to be safe and tolerable in combination with fractionated post-prostatectomy radiation therapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

A Phase 1/2 Trial of a Combination of Paclitaxel and Trastuzumab With Daily Irradiation or Paclitaxel Alone With Daily Irradiation After Transurethral Surgery for Noncystectomy Candidates With Muscle-Invasive Bladder Cancer (Trial NRG Oncology RTOG 0524)

Purpose: Bladder preservation therapy is an effective treatment for muscle-invasive urothelial carcinoma (UC). In this study we treated noncystectomy candidates with daily radiation and weekly paclitaxel for 7 weeks. Patients whose tumors showed her2/neu overexpression were additionally treated with weekly trastuzumab. Methods and Materials: Sixty-eight evaluable patients were treated with radiation therapy and either paclitaxel + trastuzumab (group 1) or paclitaxel alone (group 2). Groups were assigned on the basis of her2/neu immunohistochemistry results. Patients received 1.8-Gy fractions to a total dose of 64.8 Gy. The primary endpoint of the study was treatment-related toxicity, and secondary endpoints included complete response (CR) rate, protocol completion rate, and survival. Results: A total of 20 evaluable patients were treated in group 1 and 46 patients in group 2. Acute treatment-related adverse events (AEs) were observed in 7 of 20 patients in group 1 (35%) and 14 of 46 patients in group 2 (30.4%). Protocol therapy was completed by 60% (group 1) and 74% (group 2) of patients. Most incompletions were due to toxicity, and the majority of AEs were gastrointestinal, including 1 grade 5 AE (group 1). Two other deaths (both in group 2) were unrelated to protocol therapy. No unexpected cardiac, hematologic, or other toxicities were observed. The CR rate at 1 year was 72% for group 1 and 68% for group 2. Conclusions: In patients with muscle-invasive UC who are not candidates for cystectomy, daily radiation combined with paclitaxel is an effective treatment strategy with a high completion rate and moderate toxicity. In patients with her2/neu-positive tumors, a group generally considered to have worse outcomes, the addition of trastuzumab appears to result in comparable efficacy and toxicity. Further biomarker-driven trials should be undertaken in advancing treatment of this challenging disease.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Comparative effects of chlorpyrifos in wild type and cannabinoid Cb1 receptor knockout mice

Endocannabinoids (eCBs) modulate neurotransmission by inhibiting the release of a variety of neurotransmitters. The cannabinoid receptor agonist WIN 55.212-2 (WIN) can modulate organophosphorus (OP) anticholinesterase toxicity in rats, presumably by inhibiting acetylcholine (ACh) release. Some OP anticholinesterases also inhibit eCB-degrading enzymes. We studied the effects of the OP insecticide chlorpyrifos (CPF) on cholinergic signs of toxicity, cholinesterase activity and ACh release in tissues from wild type (+/+) and cannabinoid CB1 receptor knockout (-/-) mice. Mice of both genotypes (n = 5-6/treatment group) were challenged with CPF (300 mg/kg, 2 ml/kg in peanut oil, sc) and evaluated for functional and neurochemical changes. Both genotypes exhibited similar cholinergic signs and cholinesterase inhibition (82-95% at 48 h after dosing) in cortex, cerebellum and heart. WIN reduced depolarization-induced ACh release in vitro in hippocampal slices from wild type mice, but had no effect in hippocampal slices from knockouts or in striatal slices from either genotype. Chlorpyrifos oxon (CPO, 100 {mu}M) reduced release in hippocampal slices from both genotypes in vitro, but with a greater reduction in tissues from wild types (21% vs 12%). CPO had no significant in vitro effect on ACh release in striatum. CPF reduced ACh release in hippocampus from both genotypes ex vivo, but reduction was again significantly greater in tissues from wild types (52% vs 36%). In striatum, CPF led to a similar reduction (20-23%) in tissues from both genotypes. Thus, while CB1 deletion in mice had little influence on the expression of acute toxicity following CPF, CPF- or CPO-induced changes in ACh release appeared sensitive to modulation by CB1-mediated eCB signaling in a brain-regional manner. -- Highlights: Black-Right-Pointing-Pointer C57Bl/6 mice showed dose-related cholinergic toxicity following subcutaneous chlorpyrifos exposure. Black-Right-Pointing-Pointer Wild type and cannabinoid CB1 receptor knockout littermates responded similarly to the toxic effects of chlorpyrifos. Black-Right-Pointing-Pointer OP-induced changes in acetylcholine release appeared sensitive to modulation by CB1-mediated endocannabinoid signaling.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Co-exposure to nickel and cobalt chloride enhances cytotoxicity and oxidative stress in human lung epithelial cells

Nickel and cobalt are heavy metals found in land, water, and air that can enter the body primarily through the respiratory tract and accumulate to toxic levels. Nickel compounds are known to be carcinogenic to humans and animals, while cobalt compounds produce tumors in animals and are probably carcinogenic to humans. People working in industrial and manufacturing settings have an increased risk of exposure to these metals. The cytotoxicity of nickel and cobalt has individually been demonstrated; however, the underlying mechanisms of co-exposure to these heavy metals have not been explored. In this study, we investigated the effect of exposure of H460 human lung epithelial cells to nickel and cobalt, both alone and in combination, on cell survival, apoptotic mechanisms, and the generation of reactive oxygen species and double strand breaks. For simultaneous exposure, cells were exposed to a constant dose of 150 μM cobalt or nickel, which was found to be relatively nontoxic in single exposure experiments. We demonstrated that cells exposed simultaneously to cobalt and nickel exhibit a dose-dependent decrease in survival compared to the cells exposed to a single metal. The decrease in survival was the result of enhanced caspase 3 and 7 activation and cleavage of poly (ADP-ribose) polymerase. Co-exposure increased the production of ROS and the formation of double strand breaks. Pretreatment with N-acetyl cysteine alleviated the toxic responses. Collectively, this study demonstrates that co-exposure to cobalt and nickel is significantly more toxic than single exposure and that toxicity is related to the formation of ROS and DSB. -- Highlights: ► Decreased survival following simultaneous exposure to NiCl{sub 2} and CoCl{sub 2}. ► Enhanced caspase and PARP cleavage following co-exposure. ► Increased formation of ROS in dual exposed cells. ► N-acetyl cysteine pretreatment decreases Co and Ni toxicity. ► Co-exposure to Ni and Co enhances the formation of double strand breaks.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Inter-strain heterogeneity in rat hepatic transcriptomic responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

The biochemical and toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have been the subject of intense study for decades. It is now clear that essentially all TCDD-induced toxicities are mediated by DNA–protein interactions involving the Aryl Hydrocarbon Receptor (AHR). Nevertheless, it remains unknown which AHR target genes cause TCDD toxicities. Several groups, including our own, have developed rodent model systems to probe these questions. mRNA expression profiling of these model systems has revealed significant inter-species heterogeneity in rodent hepatic responses to TCDD. It has remained unclear if this variability also exists within a species, amongst rodent strains. To resolve this question, we profiled the hepatic transcriptomic response to TCDD of diverse rat strains (L-E, H/W, F344 and Wistar rats) and two lines derived from L-E × H/W crosses, at consistent age, sex, and dosing (100 μg/kg TCDD for 19 h). Using this uniquely consistent dataset, we show that the majority of TCDD-induced alterations in mRNA abundance are strain/line-specific: only 11 genes were affected by TCDD across all strains, including well-known dioxin-responsive genes such as Cyp1a1 and Nqo1. Our analysis identified two novel universally dioxin-responsive genes as well as 4 genes induced by TCDD in dioxin-sensitive rats only. These 6 genes are strong candidates to explain TCDD-related toxicities, so we validated them using 152 animals in time-course (0 to 384 h) and dose–response (0 to 3000 μg/kg) experiments. This study reveals that different rat strains exhibit dramatic transcriptional heterogeneity in their hepatic responses to TCDD and that inter-strain comparisons can help identify candidate toxicity-related genes.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Biotransformation of 2,3,3,3-tetrafluoropropene (HFO-1234yf) in male, pregnant and non-pregnant female rabbits after single high dose inhalation exposure

2,3,3,3-Tetrafluoropropene (HFO-1234yf) is a novel refrigerant intended for use in mobile air conditioning. It showed a low potential for toxicity in rodents studies with most NOAELs well above 10,000 ppm in guideline compliant toxicity studies. However, a developmental toxicity study in rabbits showed mortality at exposure levels of 5,500 ppm and above. No lethality was observed at exposure levels of 2,500 and 4,000 ppm. Nevertheless, increased subacute inflammatory heart lesions were observed in rabbits at all exposure levels. Since the lethality in pregnant animals may be due to altered biotransformation of HFO-1234yf and to evaluate the potential risk to pregnant women facing a car crash, this study compared the acute toxicity and biotransformation of HFO-1234yf in male, female and pregnant female rabbits. Animals were exposed to 50,000 ppm and 100,000 ppm for 1 h. For metabolite identification by {sup 19}F NMR and LC/MS-MS, urine was collected for 48 h after inhalation exposure. In all samples, the predominant metabolites were S-(3,3,3-trifluoro-2-hydroxypropanyl)-mercaptolactic acid and N-acetyl-S-(3,3,3-trifluoro-2-hydroxypropanyl)-L-cysteine. Since no major differences in urinary metabolite pattern were observed between the groups, only N-acetyl-S-(3,3,3-trifluoro-2-hydroxypropanyl)-L-cysteine excretion was quantified. No significant differences in recovery between non-pregnant (43.10 ± 22.35 μmol) and pregnant female (50.47 ± 19.72 μmol) rabbits were observed, male rabbits exposed to 100,000 ppm for one hour excreted 86.40 ± 38.87 μmol. Lethality and clinical signs of toxicity were not observed in any group. The results suggest that the lethality of HFO-1234yf in pregnant rabbits unlikely is due to changes in biotransformation patterns or capacity in pregnant rabbits. -- Highlights: ► No lethality and clinical signs were observed. ► No differences in metabolic pattern between pregnant and non-pregnant rabbits. ► Rapid and similar metabolite excretion in all groups. ► Very low amount of biotransformation in all groups (< 0.1%).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Dose–response analysis of phthalate effects on gene expression in rat whole embryo culture

The rat postimplantation whole embryo culture (WEC) model serves as a potential screening tool for developmental toxicity. In this model, cultured rat embryos are exposed during early embryogenesis and evaluated for morphological effects. The integration of molecular-based markers may lead to improved objectivity, sensitivity and predictability of WEC in assessing developmental toxic properties of compounds. In this study, we investigated the concentration-dependent effects of two phthalates differing in potency, mono(2-ethylhexyl) phthalate (MEHP) and monomethyl phthalate (MMP, less toxic), on the transcriptome in WEC to examine gene expression in relation with dysmorphogenesis. MEHP was more potent than MMP in inducing gene expression changes as well as changes on morphology. MEHP induced significant enrichment of cholesterol/lipid/steroid (CLS) metabolism and apoptosis pathways which was associated with developmental toxicity. Regulation of genes within CLS metabolism pathways represented the most sensitive markers of MEHP exposure, more sensitive than classical morphological endpoints. As shown in direct comparisons with toxicogenomic in vivo studies, alterations in the regulation of CLS metabolism pathways has been previously identified to be associated with developmental toxicity due to phthalate exposure in utero. Our results support the application of WEC as a model to examine relative phthalate potency through gene expression and morphological responses. Additionally, our results further define the applicability domain of the WEC model for developmental toxicological investigations. -- Highlights: ► We examine the effect of two phthalates on gene expression and morphology in WEC. ► MEHP is more potent than MMP in inducing gene expression changes and dysmorphogenesis. ► MEHP significantly disrupts cholesterol metabolism pathways in a dose-dependent manner. ► Specific phthalate-related mechanisms in WEC are relevant to mechanisms in vivo.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

A polymorphism in metallothionein 1A (MT1A) is associated with cadmium-related excretion of urinary beta 2‐microglobulin

Objectives: Cadmium (Cd) toxicity of the kidney varies between individuals despite similar exposure levels. In humans Cd is mainly bound to metallothioneins (MT), which scavenge its toxic effects. Here we analyzed whether polymorphisms in MT genes MT1A and MT2A influence Cd-related kidney damage. Methods: In a cross-sectional study N = 512 volunteers were selected from three areas in South-Eastern China, which to varying degree were Cd-polluted from a smelter (control area [median Cd in urine U-Cd = 2.67 μg/L], moderately [U-Cd = 4.23 μg/L] and highly [U-Cd = 9.13 μg/L] polluted areas). U-Cd and blood Cd (B-Cd) concentrations were measured by graphite-furnace atomic absorption spectrometry. MT1A rs11076161 (G/A), MT2A rs10636 (G/C) and MT2A rs28366003 (A/G) were determined by Taqman assays; urinary N-Acetyl-beta-(D)-Glucosaminidase (UNAG) by spectrometry, and urinary β2-microglobulin (UB2M) by ELISA. Results: Higher B-Cd (natural log-transformed) with increasing number of MT1A rs11076161 A-alleles was found in the highly polluted group (p-value trend = 0.033; all p-values adjusted for age, sex, and smoking). In a linear model a significant interaction between rs11076161 genotype and B-Cd was found for UNAG (p = 0.001) and UB2M concentrations (p = 0.001). Carriers of the rs11076161 AA genotype showed steeper slopes for the associations between Cd in blood and natural log-transformed UB2M (β = 1.2, 95% CI 0.72–1.6) compared to GG carriers (β = 0.30, 95% CI 0.15–0.45). Also for UNAG (natural log-transformed) carriers of the AA genotype had steeper slopes (β = 0.55, 95% CI 0.27–0.84) compared to GG carriers (β = 0.018, 95% CI − 0.79–0.11). Conclusions: MT1A rs11076161 was associated with B-Cd concentrations and Cd-induced kidney toxicity at high exposure levels. -- Highlights: ► Cadmium is toxic to the kidney but the susceptibility differs between individuals. ► The toxic effect of cadmium is scavenged by metallothioneins. ► A common variant of metallothionein 1A was genotyped in 512 cadmium exposed humans. ► Variant carriers of this polymorphism showed more kidney damage from cadmium. ► The frequency of these variants needs to be taken into account in risk assessment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

A long-term three dimensional liver co-culture system for improved prediction of clinically relevant drug-induced hepatotoxicity

Drug-induced liver injury (DILI) is the major cause for liver failure and post-marketing drug withdrawals. Due to species-specific differences in hepatocellular function, animal experiments to assess potential liabilities of drug candidates can predict hepatotoxicity in humans only to a certain extent. In addition to animal experimentation, primary hepatocytes from rat or human are widely used for pre-clinical safety assessment. However, as many toxic responses in vivo are mediated by a complex interplay among different cell types and often require chronic drug exposures, the predictive performance of hepatocytes is very limited. Here, we established and characterized human and rat in vitro three-dimensional (3D) liver co-culture systems containing primary parenchymal and non-parenchymal hepatic cells. Our data demonstrate that cells cultured on a 3D scaffold have a preserved composition of hepatocytes, stellate, Kupffer and endothelial cells and maintain liver function for up to 3 months, as measured by the production of albumin, fibrinogen, transferrin and urea. Additionally, 3D liver co-cultures maintain cytochrome P450 inducibility, form bile canaliculi-like structures and respond to inflammatory stimuli. Upon incubation with selected hepatotoxicants including drugs which have been shown to induce idiosyncratic toxicity, we demonstrated that this model better detected in vivo drug-induced toxicity, including species-specific drug effects, when compared to monolayer hepatocyte cultures. In conclusion, our results underline the importance of more complex and long lasting in vitro cell culture models that contain all liver cell types and allow repeated drug-treatments for detection of in vivo-relevant adverse drug effects. - Highlights: ► 3D liver co-cultures maintain liver specific functions for up to three months. ► Activities of Cytochrome P450s remain drug- inducible accross three months. ► 3D liver co-cultures recapitulate drug-induced liver toxicity observed in vivo. ► 3D liver co-cultures can detect species-specific drug toxicity observed in vivo. ► This in vitro model may improve assessment of human relevance of preclinical findings.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Mitochondrial dysfunction and organophosphorus compounds

Organophosphorous (OPs) pesticides are the most widely used pesticides in the agriculture and home. However, many acute or chronic poisoning reports about OPs have been published in the recent years. Mitochondria as a site of cellular oxygen consumption and energy production can be a target for OPs poisoning as a non-cholinergic mechanism of toxicity of OPs. In the present review, we have reviewed and criticized all the evidences about the mitochondrial dysfunctions as a mechanism of toxicity of OPs. For this purpose, all biochemical, molecular, and morphological data were retrieved from various studies. Some toxicities of OPs are arisen from dysfunction of mitochondrial oxidative phosphorylation through alteration of complexes I, II, III, IV and V activities and disruption of mitochondrial membrane. Reductions of adenosine triphosphate (ATP) synthesis or induction of its hydrolysis can impair the cellular energy. The OPs disrupt cellular and mitochondrial antioxidant defense, reactive oxygen species generation, and calcium uptake and promote oxidative and genotoxic damage triggering cell death via cytochrome C released from mitochondria and consequent activation of caspases. The mitochondrial dysfunction induced by OPs can be restored by use of antioxidants such as vitamin E and C, alpha-tocopherol, electron donors, and through increasing the cytosolic ATP level. However, to elucidate many aspect of mitochondrial toxicity of Ops, further studies should be performed. - Highlights: • As a non-cholinergic mechanism of toxicity, mitochondria is a target for OPs. • OPs affect action of complexes I, II, III, IV and V in the mitochondria. • OPs reduce mitochondrial ATP. • OPs promote oxidative and genotoxic damage via release of cytochrome C from mitochondria. • OP-induced mitochondrial dysfunction can be restored by increasing the cytosolic ATP.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Manipulation of the HIF–Vegf pathway rescues methyl tert-butyl ether (MTBE)-induced vascular lesions

Methyl tert-butyl ether (MTBE) has been shown to be specifically anti-angiogenic in piscine and mammalian model systems at concentrations that appear non-toxic in other organ systems. The mechanism by which MTBE targets developing vascular structures is unknown. A global transcriptome analysis of zebrafish embryos developmentally exposed to 0.00625–5 mM MTBE suggested that hypoxia inducible factor (HIF)-regulated pathways were affected. HIF-driven angiogenesis via vascular endothelial growth factor (vegf) is essential to the developing vasculature of an embryo. Three rescue studies were designed to rescue MTBE-induced vascular lesions: pooled blood in the common cardinal vein (CCV), cranial hemorrhages (CH), and abnormal intersegmental vessels (ISV), and test the hypothesis that MTBE toxicity was HIF–Vegf dependent. First, zebrafish vegf-a over-expression via plasmid injection, resulted in significantly fewer CH and ISV lesions, 46 and 35% respectively, in embryos exposed to 10 mM MTBE. Then HIF degradation was inhibited in two ways. Chemical rescue by N-oxaloylglycine significantly reduced CCV and CH lesions by 30 and 32% in 10 mM exposed embryos, and ISV lesions were reduced 24% in 5 mM exposed zebrafish. Finally, a morpholino designed to knock-down ubiquitin associated von Hippel–Lindau protein, significantly reduced CCV lesions by 35% in 10 mM exposed embryos. In addition, expression of some angiogenesis related genes altered by MTBE exposure were rescued. These studies demonstrated that MTBE vascular toxicity is mediated by a down regulation of HIF–Vegf driven angiogenesis. The selective toxicity of MTBE toward developing vasculature makes it a potentially useful chemical in the designing of new drugs or in elucidating roles for specific angiogenic proteins in future studies of vascular development. - Highlights: • Global gene expression of MTBE exposed zebrafish suggested altered HIF1 signaling. • Over expression of zebrafish vegf-a rescues MTBE-induced vascular lesions. • Inhibiting PHD or knocking down VHL rescues MTBE-induced vascular lesions. • HIF1-Vegf driven angiogenesis is a target for MTBE vascular toxicity.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Protection against acetaminophen-induced liver injury by allopurinol is dependent on aldehyde oxidase-mediated liver preconditioning

Acetaminophen (APAP) overdose causes severe and occasionally fatal liver injury. Numerous drugs that attenuate APAP toxicity have been described. However these compounds frequently protect by cytochrome P450 inhibition, thereby preventing the initiating step of toxicity. We have previously shown that pretreatment with allopurinol can effectively protect against APAP toxicity, but the mechanism remains unclear. In the current study, C3HeB/FeJ mice were administered allopurinol 18 h or 1 h prior to an APAP overdose. Administration of allopurinol 18 h prior to APAP overdose resulted in an 88% reduction in liver injury (serum ALT) 6 h after APAP; however, 1 h pretreatment offered no protection. APAP-cysteine adducts and glutathione depletion kinetics were similar with or without allopurinol pretreatment. The phosphorylation and mitochondrial translocation of c-jun-N-terminal-kinase (JNK) have been implicated in the progression of APAP toxicity. In our study we showed equivalent early JNK activation (2 h) however late JNK activation (6 h) was attenuated in allopurinol treated mice, which suggests that later JNK activation is more critical for the toxicity. Additional mice were administered oxypurinol (primary metabolite of allopurinol) 18 h or 1 h pre-APAP, but neither treatment protected. This finding implicated an aldehyde oxidase (AO)-mediated metabolism of allopurinol, so mice were treated with hydralazine to inhibit AO prior to allopurinol/APAP administration, which eliminated the protective effects of allopurinol. We evaluated potential targets of AO-mediated preconditioning and found increased hepatic metallothionein 18 h post-allopurinol. These data show metabolism of allopurinol occurring independent of P450 isoenzymes preconditions the liver and renders the animal less susceptible to an APAP overdose. - Highlights: • 18 h allopurinol pretreatment protects against acetaminophen-induced liver injury. • 1 h allopurinol pretreatment does not protect from APAP-induced injury. • 18 h or 1 h oxypurinol pretreatment does not alter APAP-induced injury. • Inhibiting aldehyde oxidase eliminates protection from 18 h allopurinol pretreatment. • 18 h allopurinol induces metallothionein which protects the liver against APAP injury.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

TCDD dysregulation of 13 AHR-target genes in rat liver

Despite several decades of research, the complete mechanism by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other xenobiotic agonists of the aryl hydrocarbon receptor (AHR) cause toxicity remains unclear. While it has been shown that the AHR is required for all major manifestations of toxicity, the specific downstream changes involved in the development of toxic phenotypes remain unknown. Here we examine a panel of 13 genes that are AHR-regulated in many species and tissues. We profiled their hepatic mRNA abundances in two rat strains with very different sensitivities to TCDD: the TCDD-sensitive Long–Evans (Turku/AB; L–E) and the TCDD-resistant Han/Wistar (Kuopio; H/W). We evaluated doses ranging from 0 to 3000 μg/kg at 19 h after TCDD exposure and time points ranging from 1.5 to 384 h after exposure to 100 μg/kg TCDD. Twelve of 13 genes responded to TCDD in at least one strain, and seven of these showed statistically significant inter-strain differences in the time course analysis (Aldh3a1, Cyp1a2, Cyp1b1, Cyp2a1, Fmo1, Nfe2l2 and Nqo1). Cyp2s1 did not respond to TCDD in either rat strain. Five genes exhibited biphasic responses to TCDD insult (Ahrr, Aldh3a1, Cyp1b1, Nfe2l2 and Nqo1), suggesting a secondary event, such as association with additional transcriptional modulators. Of the 12 genes that responded to TCDD during the dose–response analysis, none had an ED{sub 50} equivalent to that of Cyp1a1, the most sensitive gene in this study, while nine genes responded to doses at least 10–100 fold higher, in at least one strain (Ahrr (L–E), Aldh3a1 (both), Cyp1a2 (both), Cyp1b1 (both), Cyp2a1 (L–E), Inmt (both), Nfe2l2 (L–E), Nqo1 (L–E) and Tiparp (both)). These data shed new light on the association of the AHR target genes with TCDD toxicity, and in particular the seven genes exhibiting strain-specific differences represent strong candidate mediators of Type-II toxicities. - Highlights: • NanoString measured hepatic mRNA molecules following TCDD treatment. • TCDD-sensitive Long–Evans and TCDD-resistant Han/Wistar rats were compared. • Time courses and dose responses were analyzed for AHR-core gene changes. • 7 genes displayed inter-strain mRNA differences at times after TCDD exposure. • 2 of the AHR-core genes had significant inter-strain differences in their TCDD ED{sub 50}.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Kurarinol induces hepatocellular carcinoma cell apoptosis through suppressing cellular signal transducer and activator of transcription 3 signaling

Kurarinol is a flavonoid isolated from roots of the medical plant Sophora flavescens. However, its cytotoxic activity against hepatocellular carcinoma (HCC) cells and toxic effects on mammalians remain largely unexplored. Here, the pro-apoptotic activities of kurarinol on HCC cells and its toxic impacts on tumor-bearing mice were evaluated. The molecular mechanisms underlying kurarinol-induced HCC cell apoptosis were also investigated. We found that kurarinol dose-dependently provoked HepG2, Huh-7 and H22 HCC cell apoptosis. In addition, kurarinol gave rise to a considerable decrease in the transcriptional activity of signal transducer and activator of transcription 3 (STAT3) in HCC cells. Suppression of STAT3 signaling is involved in kurarinol-induced HCC cell apoptosis. In vivo studies showed that kurarinol injection substantially induced transplanted H22 cell apoptosis with low toxic impacts on tumor-bearing mice. Similarly, the transcriptional activity of STAT3 in transplanted tumor tissues was significantly suppressed after kurarinol treatment. Collectively, our current research demonstrated that kurarinol has the capacity of inducing HCC cell apoptosis both in vitro and in vivo with undetectable toxic impacts on the host. Suppressing STAT3 signaling is implicated in kurarinol-mediated HCC cell apoptosis. - Highlights: • Kurarinol induces hepatocellular carcinoma (HCC) cell apoptosis. • Kurarinol induces HCC cell apoptosis via inhibiting STAT3. • Kurarinol exhibits low toxic effects on tumor-bearing animals.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Characterization of acute biliary hyperplasia in Fisher 344 Rats administered the Indole-3-Carbinol Analog, NSC-743380

NSC-743380 (1-[(3-chlorophenyl)-methyl]-1H-indole-3-carbinol) is in early stages of development as an anticancer agent. Two metabolites reflect sequential conversion of the carbinol functionality to a carboxaldehyde and the major metabolite, 1-[(3-chlorophenyl)-methyl]-1H-indole-3-carboxylic acid. In an exploratory toxicity study in rats, NSC-743380 induced elevations in liver-associated serum enzymes and biliary hyperplasia. Biliary hyperplasia was observed 2 days after dosing orally for 2 consecutive days at 100 mg/kg/day. Notably, hepatotoxicity and biliary hyperplasia were observed after oral administration of the parent compound, but not when major metabolites were administered. The toxicities of a structurally similar but pharmacologically inactive molecule and a structurally diverse molecule with a similar efficacy profile in killing cancer cells in vitro were compared to NSC-743380 to explore scaffold versus target-mediated toxicity. Following two oral doses of 100 mg/kg/day given once daily on two consecutive days, the structurally unrelated active compound produced hepatic toxicity similar to NSC-743380. The structurally similar inactive compound did not, but, lower exposures were achieved. The weight of evidence implies that the hepatotoxicity associated with NSC-743380 is related to the anticancer activity of the parent molecule. Furthermore, because biliary hyperplasia represents an unmanageable and non-monitorable adverse effect in clinical settings, this model may provide an opportunity for investigators to use a short-duration study design to explore biomarkers of biliary hyperplasia. - Highlights: • NSC-743380 induced biliary hyperplasia in rats. • Toxicity of NSC-743380 appears to be related to its anticancer activity. • The model provides an opportunity to explore biomarkers of biliary hyperplasia.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Metabolic activation of hepatotoxic drug (benzbromarone) induced mitochondrial membrane permeability transition

The risk of drug-induced liver injury (DILI) is of great concern to the pharmaceutical industry. It is well-known that metabolic activation of drugs to form toxic metabolites (TMs) is strongly associated with DILI onset. Drug-induced mitochondrial dysfunction is also strongly associated with increased risk of DILI. However, it is difficult to determine the target of TMs associated with exacerbation of DILI because of difficulties in identifying and purifying TMs. In this study, we propose a sequential in vitro assay system to assess TM formation and their ability to induce mitochondrial permeability transition (MPT) in a one-pot process. In this assay system, freshly-isolated rat liver mitochondria were incubated with reaction solutions of 44 test drugs preincubated with liver microsomes in the presence or absence of NADPH; then, NADPH-dependent MPT pore opening was assessed as mitochondrial swelling. In this assay system, several hepatotoxic drugs, including benzbromarone (BBR), significantly induced MPT in a NADPH-dependent manner. We investigated the rationality of using BBR as a model drug, since it showed the most prominent MPT in our assay system. Both the production of a candidate toxic metabolite of BBR (1′,6-(OH){sub 2} BBR) and NADPH-dependent MPT were inhibited by several cytochrome P450 (CYP) inhibitors (clotrimazole and SKF-525A, 100 μM). In summary, this assay system can be used to evaluate comprehensive metabolite-dependent MPT without identification or purification of metabolites. - Highlights: • We constructed a sequential assay system for toxic metabolite induced MPT in one pot. • 14 drugs (e.g. benzbromarone (BBR)) induced toxic metabolite dependent MPT. • Both the production of toxic metabolite and MPT could be inhibited by CYP inhibitors. • This system could evaluate the comprehensive MPT without purification of metabolites.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Natural products induce a G protein-mediated calcium pathway activating p53 in cancer cells

Paclitaxel, etoposide, vincristine and doxorubicin are examples of natural products being used as chemotherapeutics but with adverse side effects that limit their therapeutic window. Natural products derived from plants and having low toxicity, such as quercetin, resveratrol, epigallocatechin gallate and piceatannol, have been shown to inhibit tumor cell growth both in vitro and in pre-clinical models of cancer, but their mechanisms of action have not been fully elucidated, thus restricting their use as prototypes for developing synthetic analogs with improved anti-cancer properties. We and others have demonstrated that one of the earliest and consistent events upon exposure of tumor cells to these less toxic natural products is a rise in cytoplasmic calcium, activating several pro-apoptotic pathways. We describe here a G protein/inositol 1,4,5-trisphosphate pathway (InsP3) in MDA-MB-231 human breast cancer cells that mediates between these less toxic natural products and the release of calcium from the endoplasmic reticulum. Further, we demonstrate that this elevation of intracellular calcium modulates p53 activity and the subsequent transcription of several pro-apoptotic genes encoding PIG8, CD95, PIDD, TP53INP, RRM2B, Noxa, p21 and PUMA. We conclude from our findings that less toxic natural products likely bind to a G protein coupled receptor that activates a G protein-mediated and calcium-dependent pathway resulting selectively in tumor cell death. - Highlights: • Natural products having low toxicity increase cytoplasmic calcium in cancer cells. • A G-protein/IP{sub 3} pathway mediates the release of calcium from the ER. • The elevation of intracellular calcium modulates p53 activity. • p53 and other Ca{sup 2+}-dependent pro-apoptotic pathways inhibit cancer cell growth.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Assessing interactions of binary mixtures of Penicillium mycotoxins (PMs) by using a bovine macrophage cell line (BoMacs)

Penicillium mycotoxins (PMs) are toxic contaminants commonly found as mixtures in animal feed. Therefore, it is important to investigate potential joint toxicity of PM mixtures. In the present study, we assessed the joint effect of binary combinations of the following PMs: citrinin (CIT), ochratoxin A (OTA), patulin (PAT), mycophenolic acid (MPA) and penicillic acid (PA) using independent action (IA) and concentration addition (CA) concepts. Previously published toxicity data (i.e. IC25; PM concentration that inhibited bovine macrophage (BoMacs) proliferation by 25%) were initially analyzed, and both concepts agreed that OTA + PA demonstrated synergism (p < 0.05), while PAT + PA showed antagonism (p < 0.05). When a follow-up dilution study was carried out using binary combinations of PMs at three different dilution levels (i.e. IC25, 0.5 ∗ IC25, 0.25 ∗ IC25), only the mixture of CIT + OTA at 0.5 ∗ IC25 was determined to have synergism by both IA and CA concepts with Model Deviation Ratios (MDRs; the ratio of predicted versus observed effect concentrations) of 1.4 and 1.7, respectively. The joint effect of OTA + MPA, OTA + PA and CIT + PAT complied with the IA concept, while CIT + PA, PAT + MPA and PAT + PA were better predicted with the CA over the IA concept. The present study suggests to test both IA and CA concepts using multiple doses when assessing risk of mycotoxin mixtures if the mode of action is unknown. In addition, the study showed that the tested PMs could be predicted by IA or CA within an approximate two-fold certainty, raising the possibility for a joint risk assessment of mycotoxins in food and feed. - Highlights: • We investigated the potential joint toxicity of Penicillium mycotoxin (PM) mixtures. • Independent action (IA) and concentration addition (CA) concepts were used. • 7 out of 10 mixtures followed joint toxicity described by IA or CA concepts. • Both concepts agreed that CIT + OTA mixture had synergistic interaction.

60 APPLIED LIFE SCIENCES↗