• Toxicological Research
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• 제23권2호
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• pp.135-142
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• 2007

Formononetin is an isoflavonoid phytoestrogen found in certain foodstuffs such as soy and red clover. In this study, we examined the action of formononetin with the carcinogen activation pathway mediated through the aryl hydrocarbon receptor (AhR) in MCF-7 breast carcinoma cells. Treating the cells with formononetin alone caused the accumulation of CYP1A1 mRNA as well as elevation in CYP1A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity in a dose dependent manner. However, a concomitant treatment with 7,12-dimethylbenz[a]anthracene (DMBA) and formononetin markedly reduced both the DMBA-inducible EROD activity and CYP1A1 mRNA level. Under the same conditions, formononetin inhibited the DMBA-induced AhR transactivation, as shown by reporter gene analysis using a xenobiotic responsive element (XRE). Additionally, formononetin inhibited both DMBA-inducible nuclear localization of the aryl hydrocarbon receptor (AhR) and metabolic activation of DMBA, as measured by the formation of the DMBA-DNA adducts. Furthermore, formononetin competed with the prototypical AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), for binding to the AhR in an isolated rat cytosol. These results suggest that formononetin might be considered as a natural ligand to bind on AhR and consequently produces a potent protective effect against DMBA-induced genotoxicity. Therefore, that's the potential to act as a chemopreventive agent that is related to its effect on AhR pathway as antagonist/agonist.

• Environmental Analysis Health and Toxicology
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• 제21권1호
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• pp.13-19
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• 2006

화학적 예방효과가 있는 식물성 에스트로젠은 다양한 환성을 나타내며 여러 세포 수용체와 상호작용한다. Genistein은 isoflavone의 주요물질 중의 하나로 콩류에 존재하며 대표적인 식물성 에스트로젠이다. 본 논문에서는 유방암 세포주인 MCF-7에서 aryl hydrocarbon receptor(AhR)에 의해 매개되는 발암물질 활성화 경로에 대한 genistein의 영향을 살펴보았다. 세포에 genistein을 처리할 경우 cytochrome P450 1A1(CYP1A1) 약물대사효소의 특이적인 효소반응인 7-ethoxyresorufin O-deethylase (EROD) 활성도와 CYP1A1의 유전자 발현이 genistein의 농도 의존적으로 증가하였다. Genistein과 발암물질인 방향족탄화 수소 7, 12-dimethylbenz[a]anthracene(DMBA)를 동시 처리하였을 경우 DMBA에 의해 유도되어 증가된 EROD활성도와 CYP1A1의 유전자 발현이 genistein에 의해 감소하였다. 랫트의 간에서 분리한 세포질을 이용하여 genistein과 AhR의 대표적인 ligand인 2,3,7,8-tetrachlorodibenzo-p-dioxin과 경쟁적 결합에 대한 영향을 조사한 결과 genistein이 AhR에 경쟁적으로 결합함을 알 수 있었다. 이러한 결과들은 genistein이 천연 AhR ligand임을 암시한다. 따라서, 식물성 에스트로젠인 genistein은 AhR경로의 길항제/항진제로 작용할 수 있을 것으로 사료된다.

• Archives of Pharmacal Research
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• 제29권7호
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• pp.570-576
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• 2006

Phytoestrogen biochanin A is an isoflavone derivative isolated from red clover Trifolium pratense with anticarcinogenic properties. This study examined the action of biochanin A with the carcinogen activation pathway that is mediated by the aryl hydrocarbon receptor (AhR) in MCF-7 breast carcinoma cells. Treating the cells with biochanin A alone caused the accumulation of CYP1A1 mRNA and an increase in CYP1A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity in a dose dependent manner. A concomitant treatment with 7,12-dimethylbenz[a]anthracene (DMBA) and biochanin A markedly reduced the DMBA-inducible EROD activity and CYP1A1 mRNA level. In addition, the biochanin A treatment alone activated the DNA-binding capacity of the AhR for the dioxin-response element (DRE) of CYP1A1, as measured by the electrophoretic-mobility shift assay (EMSA). EMSA revealed that biochanin A reduced the level of the DMBA-inducible AhR-DRE binding complex. Furthermore, biochanin A competed with the prototypical AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), for binding to the AhR in an isolated rat cytosol. The biochanin A competitively inhibited the metabolic activation of DMBA, as measured by the formation of the DMBA-DNA adducts. These results suggest that biochanin A may thus be a natural ligand to bind on AhR. Therefore, biochanin A may be due to act an antagonist/agonist of the AhR pathway.

• 한국환경성돌연변이발암원학회지
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• 제24권4호
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• pp.180-188
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• 2004

CYP1A1 is known to be inducible by xenobiotic compouds such as polyciclic aromatic hydrocarbons(PAHs) and 2,3,7,8-tetrachloro-dibenzo-p-dioxin(TCDD). These chemicals have been identified worldwide and can have a significant impact on the human health and well being of human and wildlife. Given these issues, the detection and quantification of these chemicals in biological, environmental and food samples is important. We investigated the effect of dietaty flavonoid, such as CYP1A1 promoter activity, 7-ethoxyresorufin-O-deethylase(EROD) activity and CYP1A1 mRNA expression induced by benzo(k)fluoranthene(B(k)F) in MCF-7 cells. Based on the three criteria of frequency of occurrence in the environment, toxicity and potential exposure to humans, B(k)F is one of the top-listed PAHs. We found that B(k)F significantly up-regulates the level of CYP1A1 promoter activity, EROD and CYP1A1 mRNA. when cells were treated with daidzein inhibited the B(k)-induced CYP1A1 prompter activity and mRNA level at high concentration. But daidzein exhibited stimulatory effects B(k)F-induced CYP1A1 promoter activity and mRNA level at low concentration. Overall, results from these studies demonstrate flavonoids might interfere the action of B(k) with AhR system to stimulate CYP1A1 gene expression.

• 한국환경성돌연변이발암원학회지
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• 제24권3호
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• pp.128-136
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• 2004

CYP1A1 is known to be inducible by xenobiotic compouds such as polyciclic aromatic hydrocarbons(PAHs) and 2,3,7,8-tetrachloro-dibenzo-p-dioxin(TCDD). These chemicals have been identified worldwide and can have a significant impact on the human health and well being of human and wildlife. Given these issues, the detection and quantification of these chemicals in biological, environmental and food samples is important. First, we investigated the effect of on CYP1A1 promoter activity, 7-ethoxyresorufin-O-deethylase(EROD) activity and CYP1A1 mRNA expression induced by benzo(k)fluoranthene(B(k)F) in MCF-7 cells. We found that B(k)F significantly up-regulates the level of CYP1A1 prompter activity, EROD and CYP1A1 mRNA. When cells were treated with genistein, it was not changed that EROD and CYP1A1 mRNA, compared to that of control. However, genistein inhibited the B(k)F-induced CYP1A1 promoter activity and mRNA level at high concentration. Furthermore, in this study, effects of HDAC(histone deacetvlase) inhibitors on human prostate cancer cells proliferation were examined. HC-toxin, SAHA and TSA inhibited cell proliferation in PC3 cells. A novel HDAC inhibitor, IN2001 also suppressed the growth of PC3 cells. And IN2001 and SAHA increased S phase and G2/M phase at 12 hrs treatment but cells were arrested G0/G1 phase at 45 hrs treatment. The HC-toxin treatment for 24 hrs and 48 hrs increased G0/G1 at low concentration ($0.1\mu\textrm{m}$) but increased G2/M at more than concentration of $1\mu\textrm{m}$. TSA increased G2/M phase. These findings height the possbility of developing HDAC inhibitors as potential anticancer therapeutic agents for the treatment of prostate cancer.

• Archives of Pharmacal Research
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• 제27권8호
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• pp.857-862
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• 2004

Naringenin, dietary flavonoid, is antioxidant constituents of many citrus fruits. In the present study, we investigated the effect of naringenin on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible CYP1 A 1 gene expression in mouse hepatoma Hepa-1c1c7 cells. Naringenin alone did not affect CYP1A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity. In contrast, the TCDD-inducible EROD activities were markedly reduced upon concomitant treatment with TCDD and naringenin in a dose dependent manner. TCDD-induced CYP1A1 mRNA level was also markedly suppressed by naringenin. A transient transfection assay using dioxin-response element (DRE)-linked luciferase and electrophoretic mobility shift assay revealed that naringe-nin reduced transformation of the aryl hydrocarbons receptor(AhR) to a form capable of specif-ically binding to the DRE sequence in the promoter of the CYP1A1 gene. These results suggest the down regulation of the CYP1A1 gene expression by either naringenin in Hepa-1c1c7 cells might be antagonism of the DRE binding potential of nuclear AhR.

• 한국환경성돌연변이발암원학회지
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• 제24권4호
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• pp.189-197
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• 2004

We investigated the effect of dietaty flavonoid, such as CYP1A1 promoter activity, 7-ethoxyresorufin-O-deethylase(EROD) activity and CYP1A1 mRNA expression induced by benzo(k)fluoranthene(B(k)F) in MCF-7 cells. Based on the three criteria of frequency of occurrence in the environment, toxicity and potential exposure to humans, B(k)F is one of the top-listed PAHs. We found that B(k)F significantly up-regulates the level of CYP1A1 promoter activity, EROD and CYP1A1 mRNA. When cells were treated with morin alonem, it was not changed that EROD and CYP1A1 mRNA, compared to that of control. However, morin inhibited the B(k)-induced CYP1A1 prompter activity and mRNA level at high concentration. But morin exhibited stimulatory effects B(k)F-induced CYP1A1 promoter activity and mRNA level at low concentration. Overall, results from these studies demonstrate morin might interfere the action of B(k) with AhR system to stimulate CYP1A1 gene expression. CYP1A1 is known to be inducible by xenobiotic compouds such as polyciclic aromatic hydrocarbons(PAHs) and 2,3,7,8-tetrachloro-dibenzo-p-dioxin(TCDD). These chemicals have been identified worldwide and can have a significant impact on the human health and well being of human and wildlife. Given these issues, the detection and quantification of these chemicals in biological, environmental and food samples is important.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2003년도 춘계학술대회
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• pp.193-193
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• 2003

Recent industrial society has human widely exposed to PAHs that are coming from the incomplete combustion of organic material as widespread environmental contaminants. Biological activities of PAHs are not known although PAHs are considered as carcinogens. The mechanism of action of PAHs has been studied extensively, however it is not clear how PAHs turn on CYPlAl in human breast cancer, Our laboratory have been studied the effect of PAHs in the human breast cancer cells, MCF-7. In this study, we examined the ZR-75-1, human breast cancer cells, as a new system to evaluate bioactivity of PAHs and to compare the PAHs action with that of MCF-7 cells. ZR-75-1 human breast cancer cell line is responsible to estrogen and progesterone. We have been able to establish long term culture system of this cells then used for the study to the effect of 13 different PAHs and environmental samples. We demonstrate that PAHs induced the CYP1A1 promoter and 7-ethoxyresorufin O-deethylase (EROD) activity in a concentration-dependent manner. RT-PCR analysis indicated that PAHs significantly up-regulate the level of CYP1A1 mRNA. Some of PAHs showed stronger stimulatory effect on CYP1 gene expression than TCDD Apparently, ZR-75-1 cells have Aryl hydrocarbon receptors (AhR), therefore it would be a good experimental tool to study the cross-talk between PAHs and steroid actions.

• 생태와환경
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• 제41권4호
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• pp.541-546
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• 2008

The purpose of this study was to evaluate ecosystem health effect in the physiological levels, based on ethoxyresorufin-O-deethylase (EROD) and total oxyradical scavenging capacity (TOSC) assays using sentinel fish species. We collected fish samples of Zacco platypus in May 2008 from 3 sampling sites including upstream, midstream, and downstream of the Gap Stream. EROD activity was averaged 4.54 in the downstream, 2.7 fold higher than upstream and indicated that stream condition was degraded along with longitudinal gradient from up to downstream. Downstream, especially was significantly increased (p < 0.01) so that indicated various pollutants including nutrient enrichment and toxicant exposure from the point sources, wastewater treatment plant and industrial complex may impact to the stream condition. In the mean time, TOSC assays showed higher in the midstream than other sites, but the values were not significant, compared to the previous report on oxidative stress. Overall results indicated that our approaches applying two biomarkers can be effectively used for diagnosis of the physiological levels in an integrative stream health assessments and can be applied as useful pre-warning techniques as a biochemical alarm system of organic pollutions.

• 생태와환경
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• 제41권3호
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• pp.331-337
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• 2008

Polycyclic aromatic hydrocarbons (PAHs) derived from leakage of fossil fuels and incomplete combustion of organic materials have been considered as harmful contaminants in environments. This study evaluated the effect of benzo[k]fluoranthene (BkF), one of the PAHs, using the multiple biomarkers and applied the integration model with those biomarker responses. After 10 days of the exposure at the measured concentrations of BkF (6, 25, and 45 ${\mu}g\;L^{-1}$), the changes of the four biomarkers, that is, 7-ethoxyresorufin-O-deethylase (EROD), DNA single-strand breaks (Comet), acetylcholinesterase (AChE) and vitellogenin (VTG) in the common carp (Cyprinus carpio) were observed. The standardized values of four biomarker responses were computed and integrated as star plots, representing Integrated Biomarker Respnse (IBR) values. DNA damage was induced in a dose-dependent manner, and increased significantly compared with that in the control. EROD and VTG levels were significantly elevated at low concentrations of BkF. On the other hand, AChE activities were not altered by BkF. IBR values increased as the exposure concentrations increased. Thus, the metabolic, endocrine and genetic changes of the biomarker responses in the common carp exposed to BkF should be considered in the case of the ecological risk assessment of the BkF in fish and it can be used as a biomonitoring tool in aquatic ecosystems. In addition, star plots can be used as a useful analysis tool in multibiomarker integration approach.