Charles G D, Bartels M J, Zacharewski T R, Gollapudi B B, Freshour N L, Carney E W
Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan 48674, USA.
Toxicol Sci. 2000 Jun;55(2):320-6. doi: 10.1093/toxsci/55.2.320.
A human breast cancer cell line, MCF-7, transiently transfected with a chimeric estrogen receptor (Gal4-HEG0) and a luciferase reporter plasmid (17m5-G-Luc), was used to investigate the estrogenic activity of benzo[a]pyrene (B[a]P), a prototypical polyaromatic hydrocarbon (PAH). B[a]P at concentrations > or = 1 microM produced responses comparable to that of 0.1 nM 17beta-estradiol (E2). The ER antagonist ICI 182,780 (ICI) completely inhibited the response to both E2 and B[a]P, indicating that the responses were ER-mediated. However, 2 microM alpha-napthoflavone (alpha-NF), an Ah receptor antagonist and P450 inhibitor, also decreased the response to B[a]P but not to E2. Analysis of the profile of B[a]P metabolites in the transfected MCF-7 cultures indicated that alpha-NF inhibited the production of the 3- and 9-hydroxy (3-OH and 9-OH), as well as the 7, 8- and 9,10-dihydroxy (7,8-OH and 9,10-OH) B[a]P species. In the ER-alpha reporter assay, the 3-OH and 9-OH metabolites produced maximal responses comparable to E2, with EC50 values of 1.2 microM and 0.7 microM, respectively. The 9,10-OH metabolite exhibited minimal activity in the assay. These responses were inhibited by ICI for both the 3-OH and the 9-OH species; however, alpha-NF inhibited only the response to the 9-OH metabolite. The 7,8-OH metabolite did not exhibit significant estrogenic activity. Furthermore, 7,8-OH B[a]P displayed observable cytotoxicity at concentrations > or = 10(-7) M. This cytotoxic response was completely inhibited by alpha-NF, suggesting that 7,8-OH B[a]P was being further metabolized to one or more cytotoxic metabolites.
使用一种人乳腺癌细胞系MCF - 7，其瞬时转染了嵌合雌激素受体（Gal4 - HEG0）和荧光素酶报告质粒（17m5 - G - Luc），来研究典型的多环芳烃苯并[a]芘（B[a]P）的雌激素活性。浓度≥1微摩尔的B[a]P产生的反应与0.1纳摩尔17β - 雌二醇（E2）相当。雌激素受体拮抗剂ICI 182,780（ICI）完全抑制了对E2和B[a]P的反应，表明这些反应是由雌激素受体介导的。然而，2微摩尔的α - 萘黄酮（α - NF），一种芳烃受体拮抗剂和细胞色素P450抑制剂，也降低了对B[a]P的反应，但对E2没有影响。对转染的MCF - 7培养物中B[a]P代谢产物谱的分析表明，α - NF抑制了3 - 羟基和9 - 羟基（3 - OH和9 - OH）以及7,8 - 二羟基和9,10 - 二羟基（7,8 - OH和9,10 - OH）B[a]P代谢产物的产生。在雌激素受体α报告基因检测中，3 - OH和9 - OH代谢产物产生的最大反应与E2相当，其半数有效浓度（EC50）值分别为1.2微摩尔和0.7微摩尔。9,10 - OH代谢产物在该检测中表现出最小的活性。ICI对3 - OH和9 - OH代谢产物的反应均有抑制作用；然而，α - NF仅抑制对9 - OH代谢产物的反应。7,8 - OH代谢产物未表现出显著的雌激素活性。此外，7,8 - OH B[a]P在浓度≥10^(-7) M时表现出明显的细胞毒性。这种细胞毒性反应被α - NF完全抑制，表明7,8 - OH B[a]P正在进一步代谢为一种或多种细胞毒性代谢产物。
