Role of eIF3f in Pancreatic Cancer

描述（由申请人提供）：调节蛋白质合成对控制细胞生长和增殖至关重要。真核起始因子3 （eIF3）是一种多蛋白复合物，在翻译过程中起重要作用。某些eIF3亚基的缺失在小鼠胚胎中具有致死性。eIF3f是eIF3复合物的p47亚基，在黑腹果蝇、秀丽隐杆线虫和拟南芥中高度保守。该试点项目研究了eIF3f表达降低通过解除翻译和细胞凋亡调控来促进胰腺癌发展的假设。eIF3f在胰腺癌中的表达明显降低。胰腺癌标本中eIF3f基因等位基因缺失。eIF3f也被证明是翻译的负调节因子。eIF3f异位表达抑制胰腺癌细胞翻译、细胞增殖和诱导凋亡。然而，没有人研究过eIF3f在胰腺肿瘤中的直接作用。由于发现较晚，胰腺癌的5年生存率低于5%。我们的长期目标是开发用于早期诊断的新型生物标志物，并确定治疗胰腺癌的新分子靶点。为了解决我们的假设，我们将追求以下具体目标：(1)确定体外和体内eIF3f的减少是否有助于胰腺肿瘤转化。利用eIF3f shRNA慢病毒构建体在永生的正常人胰腺导管上皮细胞中敲除eIF3f的表达，以评估eIF3f在体外和异种移植SCID小鼠模型中转化这些细胞的能力。eIF3f蛋白的定量免疫标记分析将使用组织微阵列上的新型量子点技术来确定eIF3f在不同阶段胰腺癌中的表达。(2)研究eIF3f抑制翻译并诱导细胞凋亡的分子机制。eIF3f作为eIF3的调控非核心亚基的功能尚不清楚。我们的初步数据表明eIF3f是翻译的负调控因子。过表达eIF3f导致核糖体减少和rRNA降解。为此，我们将研究eIF3f调控rRNA降解、翻译和凋亡的分子机制。这一建议将有助于探索新的分子途径和更好地了解胰腺癌的病因。表征这一重要的新信号通路将导致胰腺癌新的生物标志物和治疗靶点的鉴定。公共卫生相关性：eIF3f在胰腺癌中的作用胰腺癌是癌症死亡的第四大原因。这一建议将有助于探索新的分子途径和更好地了解胰腺癌的病因。表征这一重要的新信号通路将导致胰腺癌新的诊断生物标志物和治疗靶点的鉴定。

DESCRIPTION (provided by applicant): Regulation of protein synthesis is fundamentally important for the control of cell growth and proliferation. The eukaryotic initiation factor 3 (eIF3) is a multi-protein complex that plays an important role in translation. Deletion of certain eIF3 subunit is embryonic lethal in mouse. eIF3f is the p47 subunit of eIF3 complex and is highly conserved in Drosophila melanogaster, C. elegans, and Arabidopsis thaliana. This pilot project investigates the hypothesis that decreased eIF3f expression contributes to pancreatic cancer development by deregulating translation and apoptosis. The expression of eIF3f is significantly decreased in pancreatic cancer. Loss of eIF3f gene allele was observed in pancreatic cancer specimens. eIF3f was also shown to be a negative regulator of translation. Ectopic expression of eIF3f inhibits translation, cell proliferation and induces apoptosis in pancreatic cancer cells. However, no one has studied the direct role of eIF3f in pancreatic neoplasm. Pancreatic cancer has a five year survival rate under 5% because of late detection. Our long term goal is to develop novel biomarkers for early diagnosis and to identify new molecular targets for treatment of pancreatic cancer. To address our hypothesis, the following specific aims will be pursued: (1) To determine if decreased eIF3f contributes to pancreatic neoplastic transformation in vitro and in vivo. eIF3f expression will be knocked down using eIF3f shRNA lentiviral construct in immortal normal human pancreatic ductal epithelial cells to assess the ability of eIF3f to transform these cells in vitro and in the xenograft SCID mouse model. Quantitative immunolabeling analysis of eIF3f protein will be performed using novel Quantum Dot technology on tissue microarrays to define the expression of eIF3f in different stages of pancreatic cancer. (2) To characterize the molecular mechanism by which eIF3f inhibits translation and induces apoptosis. The function of eIF3f as a regulatory non-core subunit of eIF3 is not known. Our preliminary data suggest that eIF3f is a negative regulator of translation. Overexpression of eIF3f leads to reduced ribosomes and rRNA degradation. In this aim, we will investigate the molecular mechanism by which eIF3f regulates rRNA degradation, translation and apoptosis. This proposal will contribute to the exploration of novel molecular pathways and better understanding of the etiology of pancreatic cancer. Characterization of this important new signaling pathway will lead to identification of new biomarkers and therapeutic targets for pancreatic cancer. PUBLIC HEALTH RELEVANCE: Role of eIF3f in Pancreatic Cancer. Pancreatic cancer is the fourth leading cause of cancer death. This proposal will contribute to the exploration of novel molecular pathways and better understanding of the etiology of pancreatic cancer. Characterization of this important new signaling pathway will lead to identification of new diagnostic biomarkers and therapeutic targets for pancreatic cancer.