Translational control of EMT by the CELF1 RNA Binding Protein

根据一些估计，肿瘤转移是超过90%的癌症死亡率的原因。在细胞 上皮细胞向间质细胞转化（EMT）是肿瘤转移的起始事件。我们有 一直在研究翻译控制对乳腺上皮中TGF-β诱导的EMT的贡献 模型我们的初步数据明确表明，CELF 1 RNA结合蛋白，大多数 众所周知，它在1型强直性肌营养不良症中的作用，对于EMT来说是必要的，也是足够的。 系统在上皮细胞中，CELF 1蛋白通过蛋白酶体主动降解。可是 加入TGF-β和EMT后，这种蛋白质稳定，似乎增加了几种蛋白质的翻译。 靶基因，其中一些已经被定义为EMT的正调控因子。对我们 这是第一个直接证明该基因产物在EMT中作用的数据。 我们的总体目标是进一步阐明TGF-β通过以下途径诱导EMT的机制： CELF 1 protein.我们预测，对细胞机制的更深入理解， 该途径将揭示酶活性在EMT中起关键作用， 这些活性的靶向可能是预防早期转移的可行的治疗靶点， 癌症分期我们希望通过测试我们的核心假设来实现我们的目标， CELF 1蛋白通过不同下游效应蛋白的翻译激活驱动EMT。我们 我们通过三个具体目标来实现这一目标。首先，我们将确定下游效应物， CELF 1通过候选方法促进实验模型中的EMT和肿瘤转移。使用 经典的生物化学方法，我们接下来将建立TGF-β治疗的机制， 导致CELF 1蛋白水平升高。最后，我们将确定在何种程度上的错误表达 CELF 1在体内模型中影响肿瘤定植和转移，并调查了广泛的肿瘤细胞因子。 人乳腺癌，以确定CELF 1是否在这些肿瘤中错误表达， 正常组织 这项工作与癌症直接相关，因为EMT是肿瘤的核心机制 转移鉴定CELF 1稳定性和功能的酶活性， 在EMT的背景下进行控制将揭示预防EMT的候选治疗靶点。 早期癌症的转移。CELF 1蛋白的下游效应物也可能被证明是 潜在的治疗靶点，但肯定会提供深入了解细胞机制的基础 EMT可能转化为广泛的实体瘤。

By some estimates, tumor metastasis is responsible for over 90% of cancer mortality. At the cellular level, epithelial to mesenchymal transition (EMT) is the initiating event in tumor metastasis. We have been investigating the contribution of translational control to TGF-β-induced EMT in a breast epithelial model. Our preliminary data unambiguously demonstrate that the CELF1 RNA binding protein, most well known for its role in Type 1 Myotonic Dystrophy, is both necessary and sufficient for EMT in this system. In epithelial cells, the CELF1 protein is actively degraded via the proteasome. However, upon TGF-β addition and EMT, this protein is stabilized and appears to increase the translation of several target genes, some of which have already been defined as positive regulators of EMT. To our knowledge this is the first data directly demonstrating the role of this gene product in EMT. Our overall objective is to further elucidate the mechanism by which TGF-β induces EMT via the CELF1 protein. We predict that a more developed understanding of the cellular mechanisms at play in this pathway will reveal enzymatic activities playing critical roles in EMT, and that eventual therapeutic targeting of these activities may be viable therapeutic targets for the prevention of metastasis in early stage cancers. We hope to achieve our objective by testing our core hypothesis that induced stability of CELF1 protein drives EMT via translational activation of distinct downstream effector proteins. We propose doing this via three Specific Aims. First, we will identify the downstream effectors by which CELF1 promotes EMT and tumor metastasis in experimental models via a candidate approach. Using classical biochemical approaches, we will next establish the mechanism by which TGF-β treatment leads to an increase in CELF1 protein levels. Finally, we will determine to what extent misexpression of CELF1 impacts tumor colonization and metastasis in in vivo models, and survey a broad range of human breast cancers to determine whether CELF1 is misexpressed in these tumors as compared to normal tissue. The proposed work is directly relevant to cancer because EMT is a core mechanism underlying tumor metastasis. Identification of the enzymatic activities by which CELF1 stability and function are controlled in the context of EMT will reveal candidate therapeutic targets for the prevention of metastasis of early-stage cancers. Downstream effectors of the CELF1 protein may also prove to be potential therapeutic targets, but are certain to provide insight into the cellular mechanisms underlying EMT that may be translatable to a broad range of solid tumors.