Steroid hormone modulation of RET through two estrogen responsive enhancers in breast cancer
Steroid hormone modulation of RET through two estrogen responsive enhancers in breast cancer
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DOI：
10.1093/hmg/ddr291
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发表时间：
2011-10-01
影响因子：
3.5
通讯作者：
McCallion, Andrew S.
中科院分区：
文献类型：
--
作者：
Stine, Zachary E.;McGaughey, David M.;McCallion, Andrew S.
RET是先天性巨结肠和癌症中的一个致病突变基因，最近被认为与乳腺癌雌激素（E2）不依赖性和他莫昔芬耐药有关。RET显示E2和视黄酸（RA）依赖性转录调节E2反应性乳腺癌。然而，调控元件通过类固醇激素转录调控RET介导的是不明确的。最近基于全基因组染色质免疫沉淀的研究已经确定了RET基因座上10个推定的E2受体α（ESR 1）和RA受体α结合位点，我们证明其中只有两个（RET -49.8和RET +32.8）在MCF-7乳腺癌细胞中独立测定时显示出显著的E2调节反应。我们证明，内源性RET表达和RET -49.8调节活性的协同调节E2和RA在乳腺癌细胞。我们确定了RET -49.8和RET +32.8 E2反应所需的关键序列，包括已知与ESR 1、FOXA 1和TFAP 2C结合的基序。我们还报告了RET -49.8调节活性和内源性RET表达完全依赖于ESR 1的（E2）诱导，ESR 1足以介导E2诱导的RET -49.8和RET +32.8增强子活性。最后，使用斑马鱼转基因，我们还证明RET-49.8指导中枢神经系统和外周神经系统中的报告基因表达，与内源性ret表达一致。总的来说，这些数据表明，乳腺癌细胞中的RET转录是由E2通过ESR 1共同作用于多个元件来调节的。
RET, a gene causatively mutated in Hirschsprung disease and cancer, has recently been implicated in breast cancer estrogen (E2) independence and tamoxifen resistance. RET displays both E2 and retinoic acid (RA)-dependent transcriptional modulation in E2-responsive breast cancers. However, the regulatory elements through which the steroid hormone transcriptional regulation of RET is mediated are poorly defined. Recent genome-wide chromatin immunoprecipitation-based studies have identified 10 putative E2 receptor-alpha (ESR1) and RA receptor alpha-binding sites at the RET locus, of which we demonstrate only two (RET -49.8 and RET +32.8) display significant E2 regulatory response when assayed independently in MCF-7 breast cancer cells. We demonstrate that endogenous RET expression and RET -49.8 regulatory activity are cooperatively regulated by E2 and RA in breast cancer cells. We identify key sequences that are required for RET -49.8 and RET +32.8 E2 responsiveness, including motifs known to be bound by ESR1, FOXA1 and TFAP2C. We also report that both RET -49.8 regulatory activity and endogenous RET expression are completely dependent on ESR1 for their (E2)-induction and that ESR1 is sufficient to mediate the E2-induced enhancer activity of RET -49.8 and RET +32.8. Finally, using zebrafish transgenesis, we also demonstrate that RET -49.8 directs reporter expression in the central nervous system and peripheral nervous system consistent with the endogenous ret expression. Taken collectively, these data suggest that RET transcription in breast cancer cells is modulated by E2 via ESR1 acting on multiple elements collectively.