Dioxin and estrogen signaling in lung adenocarcinoma cells with different aryl hydrocarbon receptor/estrogen receptor ? phenotypes.
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ABSTRACT: Evidence suggests that estrogen affects the pulmonary response to carcinogenic pollutants, such as dioxins. In this study, we examined dioxin and estrogen signaling cross-talk in lung adenocarcinoma cell lines that were engineered to exhibit different aryl hydrocarbon receptor (AhR)/estrogen receptor (ER) ? phenotypes. Data showed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) weakly antagonized estrogen-activated ER? activity in cells expressing abundant ER?, but little AhR. Increase of AhR expression or presence of a dioxin-responsive element in proximity silenced the antiestrogenic effect of TCDD. AhR was bound to dioxin-responsive element and transcriptionally active in both TCDD-untreated and -treated lung adenocarcinoma cells. 17?-estradiol (E2) reduced basal and TCDD-induced AhR activity only in ER?-positive cells. AhR and ER? exhibited a protein-protein interaction in the presence of E2. Cotreatment with TCDD moderated this protein interaction. Colocalization of ER? and AhR at the estrogen-responsive site under E2 and TCDD/E2 treatments implied that E2???ER? might hijack AhR away from the dioxin-responsive site. Increasing the relative expression of AhR to ER? counteracted inhibition of AhR activity by E2???ER?. When AhR and ER? were both highly expressed, TCDD and E2 up-regulated expression of dual-responsive genes cytochrome P450 (CYP) 1A1 and CYP1B1 in a cumulative manner, increasing the danger of metabolic activation of carcinogens. Whereas TCDD???AhR and E2???ER? appeared to regulate CYP1B1 separately through their binding sites, E2???ER? increased the TCDD responsiveness and mRNA expression of CYP1A1 in a noncanonical way. In conclusion, AhR/ER? expression pattern, estrogen level, and promoter context determine the genomic action of dioxin in lung adenocarcinoma cells.
SUBMITTER: Kuo LC
PROVIDER: S-EPMC5459550 | biostudies-literature | 2013 Dec
REPOSITORIES: biostudies-literature
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