Role of eIF3f in Pancreatic Cancer

描述(由申请人提供)：蛋白质合成的调节对于控制细胞的生长和增殖至关重要。真核细胞起始因子3(EIF3)是一种在翻译过程中起重要作用的多蛋白质复合体。某些eIF3亚单位的缺失对小鼠是胚胎致死的。EIF3f是eIF3复合体的P47亚基，在果蝇、线虫和拟南芥中高度保守。这个试点项目调查了eIF3f表达减少通过放松对翻译和细胞凋亡的调控而导致胰腺癌发生的假说。胰腺癌组织中eIF3f的表达明显降低。胰腺癌组织中存在eIF3f等位基因缺失。EIF3f也被证明是翻译的负调控因子。异位表达eIF3f可抑制胰腺癌细胞的翻译、细胞增殖和诱导细胞凋亡。然而，还没有人研究eIF3f在胰腺肿瘤中的直接作用。由于发现较晚，胰腺癌的五年存活率低于5%。我们的长期目标是开发用于早期诊断的新生物标记物，并确定治疗胰腺癌的新分子靶点。为了解决我们的假设，我们将追求以下特定的目标：(1)确定eIF3f降低是否在体外和体内有助于胰腺肿瘤的转化。利用eIF3f shRNA慢病毒构建法在永生的正常人胰腺导管上皮细胞中下调eIF3f的表达，以评估eIF3f在体外和在异种移植的SCID小鼠模型中转化这些细胞的能力。将在组织微阵列上使用新的量子点技术对eIF3f蛋白进行定量免疫标记分析，以确定eIF3f在胰腺癌不同阶段的表达。(2)研究eIF3f抑制翻译和诱导细胞凋亡的分子机制。EIF3f作为eIF3的调控非核心亚单位的功能尚不清楚。我们的初步数据表明，eIF3f是翻译的负调控因子。EIF3f的过表达导致核糖体减少和rRNA降解。为此，我们将研究eIF3f调控rRNA降解、翻译和细胞凋亡的分子机制。这一建议将有助于探索新的分子途径，更好地了解胰腺癌的病因。对这一重要的新信号通路的表征将导致识别新的胰腺癌生物标志物和治疗靶点。公共卫生相关性：eIF3f在胰腺癌中的作用。胰腺癌是导致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，更好地了解胰腺癌的病因。对这一重要的新信号通路的表征将导致识别新的胰腺癌诊断生物标志物和治疗靶点。

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.