Translational Control by eIF3f in Pancreatic Cancer

描述（由申请人提供）：翻译失调是人类癌症发展中最重要的因素之一。因此，更好地理解翻译调控对于破译癌症发展的分子基础至关重要，并为开发新的抗癌策略提供基础。翻译起始因子eIF3在翻译过程中起着重要作用。然而，其单个亚基的功能在哺乳动物中尚未完全确定。eIF3f是eIF3复合体的一个亚基，在物种间高度保守。我们是第一个报告eIF3f在人类胰腺癌中的表达显著降低的研究小组。eIF3f蛋白表达升高可抑制肿瘤细胞生长并诱导凋亡，而eIF3f蛋白表达下调则相反。因此，eIF3f是翻译控制的关键因素，在胰腺癌的发展中起着重要作用。然而，人们对eIF3f调控翻译的潜在机制知之甚少。我们已经证明eIF3f是一种翻译抑制剂。恢复肿瘤细胞中eIF3f的表达可诱导核糖体RNA降解。因此，我们假设eIF3f通过调节rRNA降解来控制翻译。为了验证我们的假设，将追求以下具体目标：(1)表征eIF3f对核糖体RNA稳态的调节。我们将检验eIF3f结合并调节核糖体RNA降解的假设。我们将利用遗传和分子生物学技术研究eIF3f调控的28S和18S rRNA降解。(2)明确eIF3f与hnRNP K的相互作用及其在rRNA降解中的作用。我们将验证eIF3f与hnRNP K协同调节rRNA稳定性的假设。我们的初步数据显示hnRNP K与rnas结合并稳定，eIF3f直接与hnRNP K相互作用，我们将使用免疫荧光、RIP和RT-PCR研究。这两个具体目标得到了我们新颖的初步数据的支持，可以使用我们独特的研究资源独立测试，但它们是高度相关的，相互支持。从这些研究中获得的知识将在理解翻译控制的分子机制和eIF3f在翻译中的重要功能方面取得重大突破。这些将为进一步确定新的分子信号通路和胰腺癌的诊断和治疗靶点奠定基础。

DESCRIPTION (provided by applicant): Misregulated translation is one of the most important factors in cancer development in humans. Thus, a better understanding of translational regulation is essential in deciphering the molecular basis underlying cancer development, as well as providing a foundation for developing new anti- cancer strategies. Translation initiation factor eIF3 plays an important role in translation. However, the functions of its individual subunits have not yet been fully defined in mammals. eIF3f is a subunit of eIF3 complex and is highly conserved among species. We were the first group to report that the expression of eIF3f is significantly decreased in human pancreatic cancer. Increased eIF3f protein expression suppressed tumor cell growth and induced apoptosis, whereas knockdown of eIF3f expression did the opposite. Therefore, eIF3f is a critical element in translational control and it plays an important role in the development of pancreatic cancer. However, the underlying mechanisms by which eIF3f regulates translation are poorly understood. We have demonstrated that eIF3f is a translation inhibitor. Restoration of eIF3f expression in tumor cells induced ribosomal RNA degradation. Therefore, we hypothesize that eIF3f controls translation by regulating rRNA degradation. To test our hypothesis, the following specific aims will be pursued: (1) To characterize the regulation of ribosomal RNA homeostasis by eIF3f. We will test the hypothesis that eIF3f binds to and regulates ribosomal RNA degradation. We will investigate both 28S and 18S rRNA degradation regulated by eIF3f using genetic and molecular biology technologies. (2) To define the interaction between eIF3f and hnRNP K and their role in rRNA degradation. We will test the hypothesis that eIF3f coordinates with hnRNP K to regulate rRNA stability. Our preliminary data showed that hnRNP K binds to and stabilizes rRNAs, and eIF3f directly interacts with hnRNP K. Immunofluorescence, RIP and RT-PCR studies will be used. These two specific aims are supported by our novel preliminary data and can be tested independently using our unique research resources, yet they are highly interrelated and support one another. The knowledge derived from these studies will make a major breakthrough in the understanding of the molecular mechanisms implicated in translational control and the important function of eIF3f in translation. These will serve as a foundation for the further identification of novel molecular signaling pathways and targets for the diagnosis and treatment of pancreatic cancer. PUBLIC HEALTH RELEVANCE: Translational Control by eIF3f in Pancreatic Cancer Project Narrative In this proposal we will investigate the molecular mechanisms by which eIF3f regulates translation. Misregulated translation is one of the most important factors in cancer development in humans. Thus, a better understanding of translational regulation is essential in deciphering the molecular basis underlying pancreatic cancer development, as well as providing a foundation for developing new anti-cancer strategies.