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Foci formation of MCF7 cells as an in vitro screening method for estrogenic chemicals
Enmin Zou1, Mariko Hatakeyama, Fumio Matsumura
1Department of Environmental Toxicology, Institute of Toxicology and Environmental Health, ITEH, The University of California, Davis, CA 95616, USA.
Abstract:
Previously we reported a novel phenomenon that some organochlorine compounds mainly act through activation of c-Neu tyrosine kinase without being strong agonists for the estrogen receptor. In this study we tested the possibility of developing an assay system to identify estrogenic compounds acting through this c-Neu-mediated mechanism. We describe herein an assay that utilizes foci formation of MCF7 cells as an endpoint, antibody 9G6 to neutralize the c-Neu-mediated pathway and 4-hydroxytamoxifen to block the ER. Aroclors 1242 and 1248, 2,2',3,5',6-pentachlorobiphenyl (PCB 95), 2,2'-dichlorobiphenyl (PCB), cis- and trans- permethrins, and chlorothalonil were found to render estrogenic effects through this c-Neu-mediated mechanism, while α and β- endosulfans appeared to act through a pathway independent of the c-Neu-mediated one. Pentachloronitrobenzene was found to be capable of antagonizing the 17β-estradiol effect, which has never been reported previously.
Insights
This study developed a new assay to detect estrogenic compounds acting via the c-Neu tyrosine kinase pathway. Several organochlorine compounds were identified as estrogenic through this novel mechanism.
Area of Science:
- Environmental Toxicology
- Molecular Endocrinology
- Biochemistry
Background:
- Some organochlorine compounds exhibit estrogenic activity independent of estrogen receptor (ER) agonism.
- This activity is mediated through the c-Neu tyrosine kinase pathway.
Purpose of the Study:
- To develop a novel assay system for identifying estrogenic compounds acting via the c-Neu-mediated mechanism.
- To characterize the mechanisms of action for various environmental contaminants.
Main Methods:
- Utilized MCF7 cell foci formation as an endpoint.
- Employed antibody 9G6 to neutralize the c-Neu pathway.
- Used 4-hydroxytamoxifen to block the estrogen receptor.
Main Results:
- Aroclors 1242 and 1248, PCB 95, 2,2'-dichlorobiphenyl, cis- and trans- permethrins, and chlorothalonil demonstrated estrogenic effects via the c-Neu pathway.
- α and β- endosulfans acted through a c-Neu-independent pathway.
- Pentachloronitrobenzene antagonized 17β-estradiol effects, a novel finding.
Conclusions:
- The developed assay effectively identifies compounds acting through the c-Neu-mediated estrogenic pathway.
- This research expands the understanding of non-estrogenic receptor-mediated endocrine disruption.
- Identified specific organochlorines and other compounds with novel mechanisms of estrogenic action.
