• Environmental Mutagens and Carcinogens
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• v.23 no.2
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• pp.56-62
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• 2003

The liver progenitor cells could form a potential target cell population fore both tumor-initiating and -promoting chemicals. Induction of drug-metabolizing and antioxidant enzymes, including AhR-dependent CYP1A1, NQO-1 and AKR1C9, was detected in the rat liver epithelial WB-F344 "stem-like" cells. Additionally, WB-F344 cells express a functional, wild-type form of p53 protein, a biomarker of genotoxic events, and connexin 43, a basic structural unit of gap junctions forming an important type of intercellular communication. In this cellular model, two complementary assays have been established for detection of the modes of action associated with tumor promotion: inhibition of gap junctional intercellular communication (GJIC) and proliferative activity in confluent cells. We found that the PAHs and PCBs, which are AhR agonists, released WB-F344 cells from contact inhibition, increasing both DNA synthesis and cell numbers. Genotoxic effects of some PAHs that lead to apoptosis and cell cycle delay might interfere with the proliferative activity of PAHs. Contrary to that, the nongenotoxic low-molecular-weight PAHs and non-dioxin-like PCB congeners, abundant in the environment, did not significantly affect cell cycle and cell proliferation; however both groups of compounds inhibited GJIC in WB-F344 cells. The release from contact inhibiton by a mechanism that possibly involves the AhR activation, inhibition of GJIC and genotoxic events induced by environmental contaminants are three important modes of action that could play an important role in carcinogenic effects of toxic compounds. The relative potencies to inhibit GJIC, to induce AhR-mediated activity, and to release cells from contact inhibition were determined for a large series of PAHs and PCBs and their metabolites. In vitro bioassays based on detection of events on cellular level (deregulation of GJIC and/or proliferation) or determination of receptor-mediated activities in both ?$stem-like^{\circ}{\times}$ and hepatocyte-like liver cellular models are valuable tools for detection of modes of action of polyaromatic hydrocarbons. They may serve, together with concentration data, as a first step in their risk assessment.

• Korean Journal of Veterinary Research
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• v.38 no.3
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• pp.606-613
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• 1998

Cadmium is one of the well-known environmental toxicants and induces cancer in rodents and human, but its carcinogenic mechanism has not been well demonstrated until now. Genotoxic effects of cadmium in Salmonella typhimurium TA98, TA100 and TA1535/pSK1002 or in WB-F344 rat liver epithelial cells were investigated to elucidate the tumor initiating effects of cadmium. TA98, TA100 and TA1535/pSK1002 tester strains were used to detect frameshift mutation, base-pair mutation and SOS repair response, respectively, in Salmonella mutation test. Reverse mutations from histidine to $histidin^+$ of Salmonella typhimurium TA98 and TA100 by $CdCl_2$ were not significantly different from control up to the maximum doses ($100{\mu}M$ and $200{\mu}M$ in TA98 and TA100, respectively) at which non-cytotoxicity was observed. DNA SOS repair responses(${\beta}$-galactosidase activity) generally did not show significant increases compared to control in both of the conditions with or without metabolic activation in Salmonella typhimurium TA1535/pSK1002 by $CdCl_2$. But the activities of ${\beta}$-galactosidase by $400{\mu}M$ of $CdCl_2$ in metabolic activation condition and by 130 and $400{\mu}M$ of $CdCl_2$ in non-metabolic activation condition were more decreased than those of control. DNA single strand breaks for 4hrs were observed only in WB-F344 rat liver epithelial cells treated with $200{\mu}M$ of $CdCl_2$. As a conclusion, $CdCl_2$ did not induce gene mutation in microbials but induce DNA single strand breaks in rat liver epithelial cells.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.558-563
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• 2007

This study was conducted to analyze the cytotoxic effects of butylated hydroxytoluene (BHT) and propyl gallate (PG) in WB-F344 rat liver epithelial cells. Here we measured the inhibition level of gap junctional intercellular communication (GJIC) and elucidated the relationships between GJIC and mitogen-activated protein kinases (MAPKs) such as ERK, JNK, and p38. The cytotoxicities of BHT and PG appeared at concentrations of 1.0mM and 0.25mM, respectively, in the WB-F344 cells; and GJIC inhibition, which was analyzed by a scrape-loading/dye transfer assay and Western blotting analysis, appeared at 0.6mM for BHT and 0.1mM for PG, respectively. Also, the phosphorylations of Cx43, ERK, JNK, and p38 increased in dose-dependent manners. This suggests that BHT and PG treatments inhibited GJIC by the phosphorylation of MAPKs prior to cell damage.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.203-208
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• 2005

Thioacetamide (TA) is potent haptotoxincant that requires metabolic activation by mixed-function oxidases. Micrcarray technology, which is massive parallel gene expression profiling in a single hybridization experiment, has provided as a powerful molecular genetic tool for biological system related toxicant. In this study we focus on the use of toxicogenomics for the determination of gene expression analysis associated with hepatotoxicity in rat liver epithelial cell line WB-F344 (WB). The WB cells was used to assess the toxic effects of TA. WB cells were exposed to two concentrations of TA-doses which caused 20% and 50% cell death were chosen and the cells exposed for periods of 2 and 24 h. Our data revealed that following the 2-h exposure at the both of doses and 24-h exposure at the low doses, few changes in gene expression were detected. However, after 24-h exposure of the cells to the high concentration, multiple changes in gene expression were observed. TA treatment gave rise predominantly to up-regulation of genes involved in cell cycle and cell death, but down-regulation of genes involves in cell adhesion and calcium ion binding. Exposure of WB cells to higher doses of the TA gave rise to more changes in gene expression at lower exposure times. These results show that TA regulates expression of numerous genes via direct molecular signaling mechanisms in liver cells.

• Toxicological Research
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• v.14 no.4
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• pp.577-585
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• 1998

Cadmium is an important industrial and environmental pollutant and has adverse effects on cell growth and metabolism, although the mechanisms of its cellular toxicity are still unclear. This study was performed to elucidate the cytotoxic mechanism of cadmium in the viewpoint of oxidative stress and cytoskeleton alterations in WB-F344 rat liver epithelial cells. 200 $\mu\textrm{M}$ $CdCl_2$ caused a severe disassembling of microtubule and micro filament and an apparent cell retraction under an observation with fluorescence micoscope. (equation omitted)-tubulin and F-actin protein were highly thiolated at 20 min and then disappeared from 1 hour after the treatment of 200 $\mu$M CdCl$_2$in the immunoblot analysis. Intracellular GSH was decreased from 1hr to 24 hrs by 66.6 or 200 $\mu\textrm{M}$ of $CdCl_2$. Intracellular protein thiol was also decreased by 22.2, 66.6 and 200 $\mu\textrm{M}$ of $CdCl_2$ at 1 hour after its treatment. The product of lipid peroxidation (malondialdehyde) was increased from 4 hrs by 66.6 and 200$\mu\textrm{M}$ of $CdCl_2$. These data indicate that cadmium induces oxidative stress involving disassembling of microtubule and micro filament, thiolation of (equation omitted)-tubulin and actin protein, depletion of GSH and protein thiol, and increase of lipid peroxidation.

• Molecular & Cellular Toxicology
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• v.2 no.2
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• pp.120-125
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• 2006

Phenytoin is an anti-epileptic. It works by slowing down impulses in the brain that cause seizures. The recent microarray technology enables us to understand possible mechanisms of genes related to compounds which have toxicity in biological system. We have studied that the effect of a compound related to hepatotoxin in vitro system using a rat whole genome microarray. In this study, we have used a rat liver epithelial cell line WB-F344 and phenytoin as a hepatotoxin. WB-F344 was treated with phenytoin for 1 to 24 hours. Total RNA was isolated at times 1, 6 and 24h following treatment of phenytoin, and hybridized to the microarray containing about 22,000 rat genes. After analysis with clustering methods, we have identified a total of 1,455 differentially expressed genes during the time course. Interestingly, about 1,049 genes exhibited differential expression pattern in response to phenytoin in early time. Therefore, the identification of genes associated with phenytoin in early response may give important insights into various toxicogenomic studies in vitro system.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2004.05a
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• pp.35-42
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• 2004

• Proceedings of the Korean Society of Toxicology Conference
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• 2004.05a
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• pp.35-42
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• 2004

• Food Science and Biotechnology
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• v.16 no.5
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• pp.747-752
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• 2007

This study was carried out to identify and quantify the flavonoids from 6 different plant parts of Allium victorialis var. platyphyllum (AVP), including the flower, leaf, root, stem, flower stalk, and flower seed, using liquid chromatography/ mass spectrometry. Two major flavonoids were structurally identified as quercetin (3,5,7,3'4,'-pentahydroxyflavone) and kaempferol (3,5,7,4'-tetrahydroxyflavone) at contents of 11.8-25.8 and $6.0-64.4\;{\mu}g/mL$, respectively. In particular, the flower and root plant parts contained the highest amounts of quercetin and kaempferol compared to the other parts. We also assessed the recovery effects of each plant-part extract of AVP on gap junctional intercellular communication (GJIC) in WB-F344 cells by the scrape-loading and dye transfer (SL/DT) method. According to the results, GJIC was reduced by approximately 70.2% ($62.3{\pm}12.5$ cells) compared to the control ($209{\pm}9.5$ cells, 100%) when 12-O-tetradecanoylphorbol-13-acetate (TPA) was treated alone in the WB-F344 rat liver epithelial cells. However, the stem extract (0.2 mg/mL) restored GJIC to basal levels (92%, $204{\pm}2.3$ cells, p<0.01) and the flower extract (0.2 mg/mL) stimulated GJIC to 82.5% ($172.6{\pm}8.3$ cells, p<0.05), when applied together with the TPA.

• Proceedings of the Korean Society of Toxicology Conference
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• 2005.05a
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• pp.187-187
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• 2005