• Molecular & Cellular Toxicology
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• v.2 no.1
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• pp.7-10
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• 2006

We performed comprehensive SNP validation and linkage disequilibrium (LD) analysis of the c-fos induced growth factor (Figf) gene in Korean population. Out of 32 SNPs, only 9 SNPs were polymorphic in Korean population. Validated SNPs formed a single extended haplotype block with strong LD through the entire length of the gene. Tagging SNP analysis picked only 2 SNPs to represent most of the genetic variation information of the Figf gene. Our results demonstrate the utility of LD block and tagging SNP analysis for an efficient way of performing a candidate gene based association study.

• Molecular & Cellular Toxicology
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• v.2 no.1
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• pp.54-59
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• 2006

The toxicity of cadmium on Caenorhabditis elegans was investigated to identify sensitive biomarkers for environmental monitoring and risk assessment. Stress-related gene expression were estimated as toxic endpoints Cadmium exposure led to an increase in the expression of most of the genes tested. The degree of increase was more significant in heat shock protein-16.1, metallothionein-2, cytochrome p450 family protein 35A2, glutathione S-transferase-4, superoxide dismutase-1, catalase-2, C. elegans p53-like protein-1, and apoptosis enhancer-1 than in other genes. The overall results indicate that the stress-related gene expressions of C. elegans have considerable potential as sensitive biomarkers for cadmium toxicity monitoring and risk assessment.

• Molecular & Cellular Toxicology
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• v.2 no.4
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• pp.236-243
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• 2006

Microarray analysis of gene expression has become a powerful approach for exploring the biological effects of drugs, particularly at the stage of toxicology and safety assessment. Acetaminophen (APAP) has been known to induce necrosis in liver, but the molecular mechanism involved has not been fully understood. In this study, we investigated gene expression changes of APAP using microarray technology. APAP was orally administered with a single dose of 50 mg/kg or 500 mg/kg into ICR mice and the animals were sacrificed at 6, 24 and 72 h of APAP administration. Serum biochemical markers for liver toxicity were measured to estimate the maximal toxic time and hepatic gene expression was assessed using high-density oligonucleotide microarrays capable of determining the expression profile of >30,000 well-substantiated mouse genes. Significant alterations in gene expression were noted in the liver of APAP-administered mice. The most notable changes in APAP-administered mice were the expression of genes involved in apoptosis, cell cycle, and calcium signaling pathway, cystein metabolism, glutatione metabolism, and MAPK pathway. The majority of the genes upregulated included insulin-like growth factor binding protein 1, heme oxygenase 1, metallothionein 1, S100 calcium binding protein, caspase 4, and P21. The upregulation of apoptosis and cell cycle-related genes were paralleled to response to APAP. Most of the affected gene expressions were returned to control levels after 72 hr. In conclusion, we identified potential hepatotoxicity makers, and these expressions profiling lead to a better understanding of the molecular basis of APAP-induced hapatotoxicity.

• Biomolecules & Therapeutics
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• v.15 no.4
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• pp.252-260
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• 2007

As it is needed to assay possible feasibility of extrapolation between in vivo and in vitro systems and to develop a new in vitro method for toxicity testing, we investigated global gene expression from both animal and cell line treated with thioacetamide (TAA) and compared between in vivo and in vitro genomic profiles. For in vivo study, mice were orally treated with TAA and sacrificed at 6 and 24 h. For in vitro study, TAA was administered to a mouse hepatic cell line, BNL CL.2 and sampling was carried out at 6 and 24 h. Hepatotoxicity was assessed by analyzing hepatic enzymes and histopathological examination (in vivo) or lactate dehydrogenase (LDH) assay and morphological examination (in vitro). Global gene expression was assessed using microarray. In high dose TAA-treated group, there was centrilobular necrosis (in vivo) and cellular toxicity with an elevation of LDH (in vitro) at 24 h. Statistical analysis of global gene expression identified that there were similar numbers of altered genes found between in vivo and in vitro at each time points. Pathway analysis identified several common pathways existed between in vivo and in vitro system such as glutathione metabolism, bile acid biosynthesis, nitrogen metabolism, butanoate metabolism for hepatotoxicty caused by TAA. Our results suggest it may be feasible to develop toxicogenomics biomarkers by comparing in vivo and in vitro genomic profiles specific to TAA for application to prediction of liver toxicity.

• Molecular & Cellular Toxicology
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• v.3 no.2
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• pp.98-106
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• 2007

Genotoxic stress triggers a variety of biological responses including the transcriptional activation of genes regulating DNA repair, cell survival and cell death. In this study, we investigated to examine gene expression profiles and genotoxic response in TK6 cells treated with DNA damaging agents MNNG (N-methyl-N'-nitrosoguanidine) and hydrogen peroxide $(H_2O_2)$. We extracted total RNA in three independent experiments and hybridized cRNA probes with oligo DNA chip (Applied Biosystems Human Genome Survey Microarray). We analyzed raw signal data with R program and AVADIS software and identified a number of deregulated genes with more than 1.5 log-scale fold change and statistical significancy. We indentified 14 genes including G protein alpha 12 showing deregulation by MNNG. The deregulated genes by MNNG represent the biological pathway regarding MAP kinase signaling pathway. Hydrogen peroxide altered 188 genes including sulfiredoxins. These results show that MNNG and $H_2O_2$ have both uniquely regulated genes that provide the potential to serve as biomarkers of exposure to DNA damaging agents.

• Genomics & Informatics
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• v.4 no.1
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• pp.16-22
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• 2006

The KFDA (Korea Food & Drug Administration) has performed a collaborative toxicogenomics project since 2003. Its aim is to construct a toxicology database of 12 compounds administered to mice at initial phase. We chose 6-MP (6-mercaptopurine) which has been used in the treatment of childhood leukemia. It was administered at low (0.224 mg/kg) and at high (2.24 mg/kg) dose (5 mice per group) intraperitonealy to the postnatal 6 weeks mice, then the serum and liver were collected at the indicated time (6, 24 and 72 h) after scarification. Serum biochemical markers for liver toxicity were measured and histopathologic studies also were carried out. The gene expression profiling was carried out by using Applied Biosystems 1700 Full Genome Expression Mouse. By self-organization maps (SOM), we identified groups with unique gene expression patterns, some of them are supposed to be related to 6-MP induced toxicity, including lipid metabolism abnormality, inflammatory response, oxidative stress, ATP depletion and cell death. The potential toxic effects appearing as gene expression changes are dependent of the time of 6-MP but independent of the dosage of it. This study would contribute to establishment of international database as well as national one about hepatotoxicity.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.157-163
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• 2005

Because of their widespread occurrence and substantial biological activity, halogenated aromatic hydrocarbons are one of the important classes of contaminants in the environment. We have performed comparative molecular field analysis (CoMFA) on structurally diverse ligands of Ah (dioxin) receptor to explore the physico-chemical requirements for binding. All CoMFA models have given $q^{2}$ value of more than 0.5 and $r^{2}$ value of more than 0.83. The predictive ability of the models was validated by an external test set, which gave satisfactory predictive $r^{2}$ values. Best predictions were obtained with CoMFA model of combined modified training set ($q^{2}=0.631,\;r^{2}=0.900$), giving predictive residual value = 0.002 log unit for the test compound. We have suggested a model comprises of four structurally different compounds, which offers a good predictability for various ligands. Our QSAR model is consistent with all previously established QSAR models with less structurally diverse ligands. The implications of the CoMFA/QSAR model presented herein are explored with respect to quantitative hazard identification of potential toxicants.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.189-195
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• 2005

Industrial development has increase consumption of crude oil and environmental pollution. A large number of microbial lipolytic enzymes have been identified and characterized to date. To development for a new lipase with catalytic activity in degradation of crude oil as a microbial enzyme, Acinetobactor sp. B2 was isolated from soil samples that were contaminated with oil in Daejon area. Acinetobactor sp. B2 showed high resistance up to 10 mg/mL unit to heavy metals such as Ba, Li, Al, Cr, Pb and Mn. Optimal growth condition of Acinetobactor sp. B2 was confirmed $30^{\circ}C$. Lipase was purified from the supernatant by Acinetobactor sp. B2. Its molecular mass was determined to the 60 kDa and the optimal activity was shown at $40^{\circ}C$ and pH 10. The activation energies for the hydrolysis of p-nitrophenyl palmitate were determined to be 2.7 kcal/mol in the temperature range 4 to $37^{\circ}C$. The enzyme was unstable at temperatures higher than $60^{\circ}C$. The Michaelis constant $(K_{m})\;and\;V_{max}$ for p-nitrophenyl palmitate were $21.8{\mu}M\;and\;270.3{\mu}M\;min^{-1}mg\;of\;protein^{-1}$, respectively. The enzyme was strongly inhibited by $Cd{2+},\;Co^{2+},\;Fe^{2+},\;Hg^{2+},\;EDTA$, 2-Mercaptoethalol. From these results, we suggested that lipase purified from Acinetobactor sp. B2 should be able to be used as a new enzyme for degradation of crude oil, one of the environmental contaminants.

• Molecular & Cellular Toxicology
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• v.3 no.4
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• pp.299-305
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• 2007

The endocrine disrupting chemical, di (2-ethylhexyl) phthalate (DEHP) is a plasticizer used in polyvinyl chloride products ubiquitous in our daily lives. DEHP has potentially adverse effects on the liver, kidney, lung, heart, reproductive organs and endocrine systems. Many toxicological data on the DEHP toxicity have been stated, but complete protein profiles have not yet been reported. In this study, DEHP-induced oxidative DNA damage in rat lymphocyte was evaluated by Comet assay (single-cell gel electrophoresis) for the first time. Moreover, DEHP-induced protein profile alterations were examined in rat liver by using toxicoproteomic tools. 34 protein spots in the liver were identified to be significantly deregulated by DEHP on the 2-dimensional gel. Among them, 20 spots were up-regulated and 14 spots down-regulated by DEHP.

• Molecular & Cellular Toxicology
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• v.3 no.4
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• pp.246-253
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• 2007

Doxorubicin and daunorubicin are excellent chemotherapeutic agents utilized for several types of cancer but the irreversible cardiac damage is the major limitation for its use. The biochemical mechanisms of doxorubicin- and daunorubicin- induced cardiotoxicity remain unclear. There are many reports on toxicity of doxorubicin and doxorubicin in cardiomyocytes, but effects in cardiovascular system by these drugs are almost not reported. In this study, we investigated gene expression profiles in human umbilical vein endothelial cells (HUVECs) to better understand the causes of doxorubicin and doxorubicininduced cardiovascular toxicity and to identify differentially expressed genes (DEGs). Through the clustering analysis of gene expression profiles, we identified 124 up-regulated common genes and 298 down-regulated common genes changed by more than 1.5-fold by all two cardiac toxicants. HUVECs responded to doxorubicin and doxorubicin damage by increasing levels of apoptosis, oxidative stress, EGF and lipid metabolism related genes. By clustering analysis, we identified some genes as potential markers on apoptosis effects of doxorubicin and doxorubicin. Six genes of these, BBC3, APLP1, FAS, TP53INP, BIRC5 and DAPK were the most significantly affected by doxorubicin and doxorubicin. Thus, this study suggests that these differentially expressed genes may play an important role in the cardiovascular toxic effects and have significant potential as novel biomarkers to doxorubicin and doxorubicin exposure.