Crosstalk between estrogen receptor and NFkB in target gene regulation

描述（由申请人提供）：最近的证据表明，NF？B与更具侵袭性的雌激素受体（ER）阳性肿瘤、他莫昔芬耐药性的发展以及向雌激素非依赖性生长的进展相关。迄今为止，ER和NF之间的串扰的主要模式？B，已被描述为相互反式阻遏，ER拮抗NF？B活性和NF？B拮抗ER活性，但反式抑制是否有助于乳腺肿瘤进展尚不清楚。我们的初步数据表明，这是快速，强大的和协同上调多个基因的ER和NF？B以协同而非拮抗的方式起作用，这可能是乳腺癌细胞中这两种因子之间串扰的主要机制。此外，我们的研究结果表明，ER和NF？B相互作用可能在乳腺癌细胞存活中起重要作用。我们的总体目标是了解ER和NF协同基因调控的功能和机制意义？乳腺癌中的B。我们的假设是，激活NF？ER+乳腺肿瘤中的B导致促生存基因和耐药基因协同上调，这有助于乳腺肿瘤进展。为了探讨这一假设，我们建议检查NF？B激活和抑制ER+乳腺癌细胞存活和肿瘤生长以响应治疗药物（目的1）。在这些研究中，我们将把我们的注意力集中在一个协同调节，细胞存活基因在癌细胞药物反应和其表达在人类ER阳性乳腺肿瘤中的作用。探讨ER和NF？B协同调节基因转录，我们将首先检查是否在协同调节基因的5'侧翼区的反应元件的独特组合有助于通过合作ER和NF的协同作用？B DNA结合和增强的RNA Pol II募集和活化（目的2）。此外，我们将重点关注SRC/p160共激活因子和其他已知的组蛋白乙酰转移酶的基因特异性募集如何通过增强组蛋白乙酰化（Aim 3）促进协同基因转录。我们的转录研究将与生存测定相结合，以确定是否相同的潜在机制是必不可少的。两者合计，这些研究旨在提供深入了解ER和NF之间的协同串扰的分子机制？B和这种串扰在乳腺癌依赖性进展中的重要性。公共卫生相关性：我们已经确定了一些基因协同上调雌激素和促炎细胞因子在乳腺癌细胞中的ER和NF？B依赖方式。这些基因中的许多基因具有通过多种机制促进肿瘤进展的潜力，包括增加细胞存活和产生耐药性。我们的目标，这构成了这个建议的基础，是了解ER和NF的协同基因调控的功能和机制的意义？B在乳腺癌中的作用，希望这种新型的基因调节机制可以用于改善乳腺肿瘤对当前内分泌和化疗药物的反应性。

DESCRIPTION (provided by applicant): Recent evidence suggests that constitutive activation of NF?B is associated with more aggressive estrogen receptor (ER) positive tumors, the development of tamoxifen resistance, and progression to estrogen-independent growth. To date, the major mode of crosstalk between ER and NF?B that has been described is mutual transrepression, where ER antagonizes NF?B activity and NF?B antagonizes ER activity, but whether transrepression contributes to breast tumor progression is not known. Our preliminary data suggest that it is the rapid, robust and synergistic up-regulation of multiple genes by ER and NF?B acting in a synergistic rather than an antagonistic manner that may be the major mechanism of crosstalk between these two factors in breast cancer cells. Furthermore, our findings suggest that ER and NF?B interaction may play an essential role in breast cancer cell survival. Our overall objective is to understand the functional and mechanistic significance of synergistic gene regulation by ER and NF?B in breast cancer. Our hypothesis is that activation of NF?B in ER+ breast tumors leads to synergistic up-regulation of pro-survival and drug resistance genes, which contribute to breast tumor progression. To explore this hypothesis, we propose to examine the effect of NF?B activation and inhibition on ER+ breast cancer cell survival and tumor growth in response to therapeutic drugs (Aim 1). In these studies, we will focus our attention on the role of one synergistically regulated, cell survival gene in cancer cell drug response and its expression in human ER positive breast tumors. To investigate the mechanism by which ER and NF?B synergistically regulate gene transcription, we will first examine whether a unique combination of response elements in the 5' flanking region of synergistically regulated genes contributes to synergy through cooperative ER and NF?B DNA binding and enhanced RNA Pol II recruitment and activation (Aim 2). In addition, we will focus on how the gene specific recruitment of SRC/p160 coactivators, and other known histone acetyltransferases, contributes to synergistic gene transcription through enhanced histone acetylation (Aim 3). Our transcriptional studies will be coupled with survival assays to determine if the same underlying mechanisms are essential for both. Taken together these studies are designed to provide insight into the molecular mechanisms of synergistic crosstalk between ER and NF?B and the importance of this crosstalk in the progression of hormone-dependent breast cancer. PUBLIC HEALTH RELEVANCE: We have identified a number of genes synergistically up-regulated by estrogen and proinflammatory cytokines in breast cancer cells in an ER and NF?B dependent manner. Many of these genes have the potential to enhance tumor progression, through a variety of mechanisms including increased cell survival and the development of resistance to drugs. Our objective, which forms the basis of this proposal, is to understand the functional and mechanistic significance of synergistic gene regulation by ER and NF?B in breast cancer, with the hope that this novel mechanism of gene regulation may be exploited to improve breast tumor responsiveness to current endocrine and chemotherapeutic drugs.