ERa is a novel RNA-binding protein controlling breast cancer

ERα是一种新的控制乳腺癌的RNA结合蛋白 乳腺癌是世界上最常见的癌症之一，其中超过70%的乳腺癌具有以下特征： 雌激素受体α（ERα）的激活，一种关键的致癌转录因子。几乎所有关于 ERα在乳腺癌中的作用主要集中在ERα作为转录因子的作用上。 相反，我们有了一个惊人的发现，ERα是一种RNA结合蛋白（RBP），具有一个假定的RNA- 结合域（RBD）。我们对通过交联分离的RNA进行了高通量测序， 免疫沉淀（HITS-CLIP）和CRISPR分析，以解开一个独特的mRNA网络，这对 癌症进展值得注意的是，我们进一步发现，在不影响其DNA结合的情况下， 活性，在体外和体内均显著阻碍乳腺癌细胞生长。重要的是， ERα与mRNA的结合在对三苯氧胺耐药的细胞中显著增加， ERα的转录活性。ERα中RBD的突变或ERα靶点的抑制，如抗凋亡蛋白 蛋白MCL 1使耐药乳腺癌细胞对他莫昔芬诱导的细胞周期停滞和细胞死亡重新敏感。 基于这些结果，我们假设ERα是一种以前未被表征的RBP，它调节后 转录基因的表达来维持乳腺癌的进展和治疗抗性。这些发现 改变我们对ERα和乳腺癌分子基础的理解。在这项资助中，我们利用 我们令人信服的初步结果，以确定机制，ERα重编程基因表达在 转录后水平作为促进肿瘤进展和耐药性的手段。具体而言，在Aim 1，我们将利用两种最先进技术的力量来定义ERα 在mRNA稳定性和翻译水平上调节乳腺癌转录后基因表达 控制在目的2中，我们将描述ERα介导的RNA代谢刺激细胞凋亡的机制。 整合应激反应（ISR）和未折叠蛋白反应（UPR），这是适应性途径的关键 for cancer癌症development发展.我们还将描述eIF 2-eIF 2B在ERα介导的转录后调节中的作用。 调节体内癌症的发展和进展。在目标3中，我们将描述ERα作为一种 RBP在乳腺癌及其治疗意义。我们将采用优雅的遗传小鼠模型， 异种移植物和原位模型，以剖析ERα RNA结合活性在体内的作用。因此，我们将 在揭示ERα RNA结合活性在肿瘤发生、发展、转移中的作用方面处于有利地位。 形成和治疗反应。

ERα is a novel RNA-binding protein controlling breast cancer Breast cancer is one of the most common cancers in the world, with over 70% of breast cancers harboring the activation of the estrogen receptor α (ERα), a key oncogenic transcription factor. Almost all research on the function of ERα in breast cancer has been predominantly centered on the role of ERα as a transcription factor. We have instead made a striking discovery that ERα is an RNA-binding protein (RBP) with an ascribed RNA- binding domain (RBD). We performed high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP) and CRISPR analyses to unravel a unique network of mRNAs, crucial for cancer progression. Notably, we further discovered that mutating the ERα RBD, without affecting its DNA-binding activity, significantly impedes breast cancer cell growth both in vitro and in vivo. Importantly, the percentage of ERα binding to mRNA is significantly increased in cells resistant to tamoxifen, an antagonist targeting the transcriptional activity of ERα. Mutation of the RBD in ERα or inhibition of targets of ERα such as the antiapoptotic protein MCL1 re-sensitize resistant breast cancer cells to tamoxifen-induced cell cycle arrest and cell death. Based on these results, we hypothesize that ERα is a previously uncharacterized RBP that modulates post- transcriptional gene expression to sustain breast cancer progression and therapy resistance. These findings transform our understanding of ERα and the molecular underpinnings of breast cancer. In this grant, we leverage our compelling preliminary results to define the mechanisms by which ERα reprograms gene expression at the post-transcription level as a means to contribute to tumor progression and drug resistance. Specifically, in Aim 1, we will harness the power of two state-of-the-art technologies to define the mechanisms by which ERα regulates post-transcriptional gene expression in breast cancer at the level of mRNA stability and translation control. In Aim 2, we will delineate the mechanisms by which ERα-mediated RNA metabolism stimulates the Integrated stress response (ISR) and Unfolded Protein Response (UPR), which are adaptive pathways critical for cancer development. We will also characterize the role of eIF2-eIF2B in ERα-mediated post-transcriptional regulation in cancer development and progression in vivo. In Aim 3, we will characterize the role of ERα as an RBP in breast cancer and its therapeutic implications. We will employ elegant genetic mouse models as well as xenografts and orthotopic models to dissect the role of ERα RNA-binding activity in-vivo. Therefore, we will be in a strong position to unveil the function of ERα RNA-binding activity on tumor initiation, progression, metastasis formation, and therapeutic response.