• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05b
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• pp.59-72
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• 2002

The anticarcinogenic effects of epicatechin(EC) and ginsenoside Rb2(Rb2), which are major components of green tea and Korea ginsen, respectively, were investigated using a model system of gap junctional intercellular communication (GJIC) in WB-F344 rat liver epithelial cells. 12-O-Tetradecanoylphorbol-13-accetate (TPA) and hydrogen preoxide, known as cancer promoters, inhibited GJIC in the epithelial cells as determined by the scrape loading/dye transfer assay, fluorescence redistribution assay after photobleaching, and immunofluorescent staining of connexin 43 using a laser confocal microscope. The inhibition of GJIC by TPA and H2O2 was prevented with treatment of Rb2 or Ec. The effect of EC on GJIC was stronger in TPA-treated cells than in H2O2-treated cells, while the effect of Rb2 was opoosite to that of EC. EC, at the concentration of 27.8$\mu$g/ml, prevented the TPA-induced GJIC inhibition by about 60%. Rb2, at the concentration of 277$\mu$g/ml, recovered the H2O2-induced GJIC inhibition by about 60%. These results suggest that Rb2 and EC may prevent human cancers by preventing the down-regulation of GJIC during the cancer promotion phase and that the anticancer effect of green tea and Korea ginseng may come from the major respective conponents, EC and Rb2.

• 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.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.3
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• pp.207-214
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• 1997

We collected airborne complex mixtures in a industrial area of Yeochun, and examined whether these complex mixtures could affect gap junctional intercellular communication (GJIC) in a cultured WBF-344 rat liver epithelial cells (LEC). Since the reduction of GJIC plays an important role in chemical carcinogenesis, measurement of changes of GJIC is a meaningful method to screen carcinogenicity of these mixtures. High and low volume samples were dissolved in dimethyl sulfoxide (DMSO) and tested. Blank filter extractions were also examined for exclud-ing possible toxicity of filter itself, and TPA (12-O-tetradecanoylphorbol-13-acetate) and DMSO were used as positive and negative control, respectively. When the cells were exposed to samples at concentration below that required to maintain rather than 85% cell viability based on the result of neutral red uptake assay, maximal inhibition of GJIC was observed at 1hr after treatment with both high and low volume samples by scrape-loading dye transfer assay. In fluorescence recovery after photobleaching assay, recovery rates via gap junctions were 33%/min in high volume sample and 62%/min in low volume sample. In together, airborne samples collected in Yeochun inhibited GJIC in a cultured WBF-344 rat LEC. These results suggest airborne samples tested in this experiment may attribute to cause a certain type and degree of cancers in in vivo when exposured for some periods.

• 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.

• Journal of Food Hygiene and Safety
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• v.21 no.4
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• pp.269-273
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• 2006

Potassium Sorbate (PS) is a potassium salt version of sorbic acid, which has antimicrobial and fungistatic features in foods. Therefore, PS is used as a food preservative against fungi and mold. PS has been found to be non-toxic even when taken in large quantities given its trait to be broken down in the body into water and carbon dioxide. Gap Junctional Intercellular Communication (GJIC) is essential in the maintenance of tissue homeostasis during development and differentiation. This study was made of the effects of PS on GJIC in WB-F344 rat liver epithelial (WB) cells. We found dramatic decrease of cell viability in time- and dose-dependent manners when WB cells were treated with PS. The effect of PS on GJIC is strong inhibition, and it took place in parallel with a hyperphosphorylation of connexin 43 expression. The finding that PS interferes with gap junction functionality should be considered with respect to the mechanism of PS-induced hepatotoxicity.

• Journal of Ginseng Research
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• v.30 no.2
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• pp.64-69
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• 2006

Gap junctional channels, allowing rapid intercellular communication and synchronization of coupled cell activities, play crucial roles in many signaling processes, including a variety of cell activities. Consequently, a modulation of the gap junctional intercellular communication (GJIC) should be a potential pharmacological target. In the present, the GJIC of a epithelial-derived rat mammary cells (BICR-M1Rk) was assessed in the presence of ginseng saponin, by using an established method of scrape-loading dye transfer assay. The transfer of Lucifer yellow (diameter: 1.2 nm) among the neighboring BICR-M1Rk cells, in which connexin43 (Cx43) is a major gap junction channel-forming protein, was significantly retarded at a concentration of $10{\mu}g/ml$ ginseng saponin. By using both methods of RT-PCR and Western blotting, it was demonstrated that ginseng saponin modulated neither the mRNA synthesis of Cx43 nor the translational process of Cx43. This ginseng saponin-induced modification of GJIC was a similar phenomenon observed under the $\beta$-glycyrrhetinic acid treatment, a well-known gap junction channel blocker. Taken together, it is reasonable to conclude that the ginseng saponin inhibits GJIC only by modulating the gating property of gap junction channels.

• Natural Product Sciences
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• v.5 no.2
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• pp.88-92
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• 1999

Inhibition of gap junction-mediated intercellular communication (GJIC) has been considered as an important factor in the tumor promotion phase of carcinogenesis. Recovery effects of natural products on gap junctional intercellular communication are measured by scrape-loading and dye transfer method using Lucifer yellow after administration of phorbol-12-myristate-13-acetate (PMA) on WBF344 cells. Among tested natural products, the hexane fraction and subfractions (F-01 and F-04) of Setaria italica were relatively effective for recovery of GJIC. The hexane fraction of Setaria italica $(EC_{25},\;12.14\;{\mu}g/ml)$ and subfractions $(F-01:EC_{50},\;10.74\;{\mu}g/ml;EC_{25},\;1.58\;{\mu}g/ml,\;F-04:EC_{50},\;11.03\;{\mu}g/ml;\;EC_{25},\;3.12\;{\mu}g/ml)$ revealed dose-dependent recovery effects on GJIC. Our data show GJIC activity measurement by Lucifer yellow spread on cells can be an effective tool for the screening of natural products with possible cancer chemopreventive effects.

• 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.

• Journal of the East Asian Society of Dietary Life
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• v.24 no.3
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• pp.359-367
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• 2014

This study analyzed phytochemicals, including various carotenoids, tocopherol and L-ascorbic acid, in green, yellow and orange paprikas (GP, YP and OP) and measured the preventive effects of lipophilic extracts from different colored paprikas on the blockage of gap junctional intercellular communication (GJIC), which is known as a cellular event associated with tumor promotion. Main carotenoids were lutein and ${\beta}$-carotene in GP, lutein, ${\beta}$-carotene, capsanthin, violaxanthin, ${\beta}$-carotene and capsorubin in YP, and lutein, ${\beta}$-carotene, cryptoxanthin and zeaxanthin in OP. Total carotenoid contents were $65.54{\pm}15.87$ mg/100 g dw in OP, $11.98{\pm}0.69$ mg/100 g dw in YP and $10.30{\pm}1.43$ mg/100 g dw in GP. Tocopherol contents were highest in GP compared with in YP and OP, whereas L-ascorbic acid contents were very high in all paprikas. We determined the non-cytotoxic levels of paprika extracts by MTT assay, which showed less formation of reactive oxygen species (ROS) induced by $500{\mu}M$ $H_2O_2$ for 1h. Finally, we showed that pretreatment of paprika extracts prevented inhibition of GJIC induced by $500{\mu}M$ $H_2O_2$ by the scrape-loading/dye-transfer technique. In conclusion, each colored paprika has unique phytochemicals and showed a protective effect on inhibition of GJIC.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.123-123
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• 2003

Primary cultures of rat fetus brain exhibit phenotypes of neuron, oligodendrocyte, and astrocyte from "neurospheres". To understand the role of mitogen-activated protein kinase (MAPK) cascade and gap junctional intercellular communication (GJIC) in the differentiation of neurosphere-derived astrocyte, we investigated the effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the cultured astrocyte morphology.(omitted)