Targeting Translation Dependence in Colorectal Cancer Progression

描述（由申请人提供）：RAS/RAF/MEK/ERK和PI3K/AKT通路的突变激活与结直肠癌（CRC）的进展和转移有关。几种小分子靶向PI3K、AKT、RAF和MEK抑制剂已在临床用于治疗结直肠癌，但作为单一药物仅显示出有限的活性。我们最近发现，通过有效抑制eif4e启动的帽依赖翻译，抑制ERK和AKT通路在体外和体内均表现出有效的协同抗crc作用。我们的总体假设是，通过ERK和AKT信号的协同激活cap依赖性翻译可以选择性地上调导致结直肠癌进展和转移的关键癌蛋白。通过表征ERK和AKT信号协同激活cap依赖性翻译的分子细节，我们旨在了解CRC转移进展中翻译激活的分子机制，并探索靶向翻译调控在CRC治疗中的治疗应用。我们的具体目标是：确定ERK和AKT信号在结直肠癌中协同翻译激活的生物学和治疗后果。我们将确定1)mTOR激酶在CRC细胞生长和运动的翻译调节中整合ERK和AKT信号功能的程度；2) mTOR抑制诱导的ERK和AKT的反馈激活如何解除帽依赖性翻译并导致mTOR不依赖性；3)利用我们已经建立的CRC原位转移模型，研究转移进展调节翻译活性的分子基础。目标2。研究ERK和AKT信号协同激活CRC进展和转移的分子机制。我们证明survivin是ERK和AKT通路的关键翻译靶点。我们将探讨翻译调节的survivin作为这些途径中重要的生长/转移促进因子的可能机制。我们将结合多体分析和蛋白质组学方法，系统地鉴定其他被多体选择性招募并通过ERK和AKT信号转译的mrna，并详细表征这些基因在结直肠癌进展和转移中的功能重要性。目标3。评估联合抑制MEK/ERK和AKT/mTOR通路并靶向其信号在翻译起始上的收敛以增强CRC治疗的体内效用。我们将使用小鼠原位CRC模型和患者肿瘤衍生异种移植模型来确定MEK、AKT和mTOR抑制剂单独或联合使用的有效性，并表征翻译起始抑制剂4EGI-1阻止肿瘤进展和转移的能力。eIF4E、4E-BP1和survivin的表达和调控，以及它们与ERK和AKT通路突变激活状态的相关性，也将在靶向治疗和临床标本中得到表征。

DESCRIPTION (provided by applicant): Mutational activation of the RAS/RAF/MEK/ERK and PI3K/AKT pathways is associated with colorectal cancer (CRC) progression and metastasis. Several small molecularly-targeted PI3K, AKT, RAF and MEK inhibitors have been tested in the clinic for the treatment of CRC but have shown only limited activity as a single agent. We have recently discovered that inhibition of both the ERK and AKT pathways exhibits potent, synergistic anti-CRC effects, both in vitro and in vivo, by effectively inhibiting eIF4E-initiated cap-dependent translation. Our overarching hypothesis is that the activation of cap-dependent translation by cooperative ERK and AKT signaling can selectively upregulate key oncoproteins that confer CRC progression and metastasis. By characterizing the molecular details of the activation of cap-dependent translation by cooperative ERK and AKT signaling, we aim to understand the molecular mechanisms underlying translational activation for CRC metastatic progression, and to explore the therapeutic applications of targeting translational regulation for CRC treatment. Our Specific Aims are: Aim 1. Determine the biologic and therapeutic consequences of translational activation by cooperative ERK and AKT signaling in CRC. We will determine 1) the extent to which the mTOR kinase integrates the function of ERK and AKT signaling in translational regulation of CRC cell growth and motility; 2) how mTOR inhibition-induced feedback activation of ERK and AKT deregulates cap-dependent translation and causes mTOR-independence; and 3) the molecular basis of metastatic progression-modulated translational activity using our well-established orthotopic metastastic model of CRC. Aim 2. Characterize the molecular mechanism of translational activation by cooperative ERK and AKT signaling for CRC progression and metastasis. We demonstrate that survivin is a key translational target of the ERK and AKT pathways. We will explore the possible mechanism by which the translationally-regulated survivin acts as an important growth/metastasis-promoting effector of these pathways. We will use combined polysome profiling and proteomic approaches to systematically identify other mRNAs that are selectively recruited to polysomes and translated by cooperative ERK and AKT signaling, and characterize in detail the functional importance of these genes in CRC progression and metastasis. Aim 3. Evaluate the in vivo utility of combined inhibition of the MEK/ERK and AKT/mTOR pathways and targeting the convergence of their signals on translation initiation for enhancing CRC therapy. We will use both the mouse orthotopic model of CRC and the patient tumor-derived xenograft model to determine the effectiveness of MEK, AKT and mTOR inhibitors alone and in combination, and to characterize the ability of the translation initiation inhibitor 4EGI-1 to prevent tumor progressio and metastasis. The expression and modulation of eIF4E, 4E-BP1 and survivin, and their correlation with the mutational activation status of ERK and AKT pathways will also be characterized in response to the targeted therapies and in clinical specimens.