Chang Edmund C, Charn Tze Howe, Park Sung-Hee, Helferich William G, Komm Barry, Katzenellenbogen John A, Katzenellenbogen Benita S
Department of Molecular, University of Illinois, Urbana, Illinois 61801-3704, USA.
Mol Endocrinol. 2008 May;22(5):1032-43. doi: 10.1210/me.2007-0356. Epub 2008 Feb 7.
Estrogen receptors alpha and beta (ERalpha and ERbeta) mediate the actions of estrogens in a variety of normal and cancer target cells. Estrogens differ in their preference for these ERs, and many phytoestrogens bind preferentially to ERbeta. To investigate how phytoestrogens such as genistein impact ER-regulated gene expression, we used adenoviral gene delivery of ERbeta coupled with ERalpha depletion with small interfering RNA to generate human breast cancer (MCF-7) cells expressing four complements of ERalpha and ERbeta. We examined the dose-dependent effects of genistein on genome-wide gene expression by DNA microarrays and monitored the recruitment of ERs and coregulators to responsive regions of estrogen-regulated genes. At a low (6 nm) concentration, genistein regulated gene expression much more effectively in cells coexpressing ERalpha and ERbeta than in cells expressing ERalpha alone, whereas at high concentration (300 nm), genistein induced transcriptome changes very similar to that of 17beta-estradiol. We demonstrate that ERbeta is preferentially activated by genistein and is recruited to estrogen-responsive genomic sites and that differential occupancy of ERalpha and ERbeta by genistein and 17beta-estradiol in turn influences the recruitment patterns of coregulators such as steroid receptor coactivator 3 (SRC3) and receptor-interacting protein 140 (RIP140). Our observations indicate that genistein is a potency-selective ligand for gene expression regulation by ERalpha and ERbeta and that the ability of ERalpha and ERbeta to serve as determinants of gene expression is greatly influenced by the nature of the ligand, by ligand dose, and by the differential abilities of ligand-ER complexes to recruit different coregulators at ER binding sites of hormone-regulated genes.
雌激素受体α和β（ERα和ERβ）介导雌激素在多种正常和癌细胞靶细胞中的作用。雌激素对这些雌激素受体的偏好不同，许多植物雌激素优先与ERβ结合。为了研究染料木黄酮等植物雌激素如何影响雌激素受体调节的基因表达，我们使用腺病毒基因递送ERβ并结合小干扰RNA耗尽ERα，以生成表达四种ERα和ERβ互补体的人乳腺癌（MCF-7）细胞。我们通过DNA微阵列检查了染料木黄酮对全基因组基因表达的剂量依赖性影响，并监测了雌激素受体和共调节因子募集到雌激素调节基因的反应区域的情况。在低浓度（6 nM）下，染料木黄酮在共表达ERα和ERβ的细胞中比在仅表达ERα的细胞中更有效地调节基因表达，而在高浓度（300 nM）下，染料木黄酮诱导的转录组变化与17β-雌二醇非常相似。我们证明染料木黄酮优先激活ERβ并募集到雌激素反应性基因组位点，并且染料木黄酮和17β-雌二醇对ERα和ERβ的不同占据反过来影响共调节因子如类固醇受体共激活因子3（SRC3）和受体相互作用蛋白140（RIP140）的募集模式。我们的观察结果表明，染料木黄酮是一种通过ERα和ERβ进行基因表达调节的效价选择性配体，并且ERα和ERβ作为基因表达决定因素的能力受到配体性质、配体剂量以及配体-雌激素受体复合物在激素调节基因的雌激素结合位点募集不同共调节因子的不同能力的极大影响。
