Gozgit Joseph M, Nestor Kathleen M, Fasco Michael J, Pentecost Brian T, Arcaro Kathleen F
Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA 01003-9298, USA.
Toxicol Appl Pharmacol. 2004 Apr 1;196(1):58-67. doi: 10.1016/j.taap.2003.12.003.
Polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants that have been extensively studied for multiple toxicological endpoints in both laboratory animals and humans. The purpose of this study was to investigate the estrogenicity of PAHs in the human breast cancer cell line MCF-7. We investigated 14 PAHs for their ability to bind either the estrogen receptor (ER) or the aryl hydrocarbon receptor (AhR) and to activate target gene expression. PAHs were tested in a human recombinant estrogen receptor (hrER) competitive binding assay, and in both an estrogen response element (ERE)- and xenobiotic response element (XRE)-mediated reporter gene assay. We used quantitative RT-PCR to examine selected PAHs that showed activity in the ERE reporter gene assay for their ability to upregulate estrogen-responsive genes HEM45, progesterone receptor, and pS2, and the aryl hydrocarbon-responsive CYP1A1 gene. None of the 14 PAHs bound the hrER, but five of the PAHs (anthracene, B[a]A, chrysene, B[b]F, and B[a]P) induced ER-reporter activity. This activity was dependent on the metabolism of PAHs in MCF-7 cells via the AhR pathway, which resulted in the formation of metabolites that bound the ER. None of the five PAHs that induced the ER-reporter were found to upregulate estrogen-responsive genes, yet four of the five PAHs induced AhR-dependent CYP1A1 gene expression. In contrast, a metabolite of B[a]P, 3'OH-B[a]P, and a PCB metabolite, 4'OH-2,4,6-BP, did weakly upregulate all three estrogen-responsive genes. Data from these studies indicate that induction of ER-reporter activity alone does not necessarily parallel endogenous gene transcription, and that the reporter gene assay may detect interactions that are not functional in vivo.
多环芳烃（PAHs）是常见的环境污染物，已在实验动物和人类中针对多种毒理学终点进行了广泛研究。本研究的目的是调查PAHs在人乳腺癌细胞系MCF-7中的雌激素活性。我们研究了14种PAHs结合雌激素受体（ER）或芳烃受体（AhR）以及激活靶基因表达的能力。PAHs在人重组雌激素受体（hrER）竞争性结合试验以及雌激素反应元件（ERE）和异生物素反应元件（XRE）介导的报告基因试验中进行了测试。我们使用定量RT-PCR检测在ERE报告基因试验中表现出活性的选定PAHs上调雌激素反应基因HEM45、孕激素受体和pS2以及芳烃反应性CYP1A1基因的能力。14种PAHs均未结合hrER，但其中5种PAHs（蒽、苯并[a]蒽、 Chrysene、苯并[b]荧蒽和苯并[a]芘）诱导了ER报告活性。这种活性依赖于MCF-7细胞中PAHs通过AhR途径的代谢，这导致了与ER结合的代谢产物的形成。诱导ER报告的5种PAHs均未上调雌激素反应基因，但其中4种PAHs诱导了AhR依赖性CYP1A1基因表达。相比之下，苯并[a]芘的一种代谢产物3'OH-苯并[a]芘和一种多氯联苯代谢产物4'OH-2,4,6-BP确实微弱地上调了所有三种雌激素反应基因。这些研究的数据表明，仅诱导ER报告活性不一定与内源性基因转录平行，并且报告基因试验可能检测到在体内无功能的相互作用。
