The role of Pdcd4 in colorectal tumor progression

Pdcd4在结直肠肿瘤进展中的作用

• 批准号: 8197127
• 负责人: Hsin-Sheng Yang
• 金额: $ 29.49万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2013-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8197127
• 关键词: 5' Untranslated Regions; Address; Apoptosis; Binding; Binding Sites; Biological Assay; Cancer Etiology; Cancerous; Cells; Cessation of life; Colon; Colon Carcinoma; Colonic Neoplasms; Colorectal Cancer; Colorectal Neoplasms; Complex; Cultured Cells; Dominant-Negative Mutation; Down-Regulation; E-Cadherin; Epithelial; Fibroblasts; Fractionation; Free Energy; Gene Expression; Gene Targeting; Genetic Transcription; HT29 Cells; Health; In Vitro; Injection of therapeutic agent; Intervention; Knowledge; Liver; MAPK8 gene; Malignant Neoplasms; Measures; Mesenchymal; Messenger RNA; Methods; Molecular; Mus; Mutate; Mutation; Neoplasm Metastasis; Normal tissue morphology; Nude Mice; Oncogene Activation; Polyribosomes; Prevention; Primary Neoplasm; Process; Proteins; Publications; Reagent; Reverse Transcription; Role; Site-Directed Mutagenesis; Slug protein; Staining method; Stains; Structure; Testing; Tissues; Transcription Factor AP-1; Transcription Repressor/Corepressor; Translational Repression; Translations; Tumor Cell Invasion; Tumor Suppressor Proteins; Tumor Tissue; Tumor-Suppressor Gene Inactivation; United States; Up-Regulation; Work; base; c-myc Genes; cancer cell; chromatin immunoprecipitation; design; epithelial to mesenchymal transition; implantation; in vivo; inhibitor/antagonist; insight; knock-down; lymph nodes; mutant; neoplastic cell; novel; novel therapeutics; prevent; promoter; slug; translation assay; tumor progression

DESCRIPTION (provided by applicant): Colorectal cancer is the second leading cause of cancer-related deaths in the United States, largely due to invasion and metastasis to the liver and lymph nodes. Thus, a thorough understanding of invasion/metastasis is necessary for prevention and treatment of colon cancer. Over- expression of programmed cell death 4 (Pdcd4), a novel tumor suppressor, inhibits invasion and AP-1 dependent transcription in colon tumor cells. Pdcd4 expression is frequently down-regulated in colon tumor tissues as compared to adjacent normal tissues. The objective of the proposed study is to define the function of Pdcd4 in tumor invasion/metastasis and elucidate the molecular mechanisms involved in these processes. We knocked down Pdcd4 expression in colon tumor GEO and HT29 cells and found that Pdcd4 knock-down triggers morphological changes, induces invasion, and activates 2-catenin/Tcf and AP-1 dependent transcription. Our preliminary results further demonstrated that a decrease in E-cadherin expression correlates with an increase in the protein level of Slug, a transcription repressor for E-cadherin expression. We, therefore, hypothesize that Pdcd4 knock-down promotes colon tumor cell invasion/metastasis through down-regulation of E-cadherin and activation of 2-catenin/Tcf and AP-1 dependent transcription. To test our hypothesis, four Specific Aims are proposed. Aim 1: determine whether Pdcd4 functions as a metastasis inhibitor in colon tumor cells. Epithelial-to-mesenchymal transition and metastasis in mice will be assayed using Pdcd4 knock- down and over-expressed cells. Aim 2: examine whether activation of 2-catenin/Tcf dependent transcription led by E-cadherin down-regulation in Pdcd4 knock-down cells promotes invasion/metastasis. We will test activation of 2-catenin/Tcf dependent transcription by knocking down E-cadherin, reversion of the invasive/metastatic ability by inhibiting 2-catenin/Tcf dependent transcription, verification of uPAR and c-Myc as the target genes of 2-catenin/Tcf dependent transcription, and inhibition of 2-catenin/Tcf4 dependent transcription and its target gene expression by over-expressing Pdcd4. Aim 3: determine whether activation of 2-catenin/Tcf4 dependent transcription in Pdcd4 knock-down cells up-regulates MAP4K1 expression and AP-1 activity through c-Myc. We will establish the c-Myc as a regulator of MAP4K1 expression, and activation of 2- catenin/Tcf dependent transcription causing up-regulation of MAP4K1 expression, JNK activation, and AP-1 dependent transcription. Aim 4: determine whether Pdcd4 translationally inhibits transcription repressor Slug expression resulting in up-regulation of E-cadherin and suppression of invasion/metastasis. Translation inhibition and the inhibitory mechanism will be analyzed using in vitro and in vivo translation assays followed by an examination of E-cadherin expression level and the ability of invasion/metastasis in Slug knock-down and Pdcd4 expressing cells. This work will provide a comprehensive understanding of how Pdcd4 modulates colon tumor progression and holds great promise for novel interventions for preventing and treating colon cancer. PUBLIC HEALTH RELEVANCE Colorectal cancer is the second most fatal cancer in the United States, largely due to invasion and metastasis to the liver and lymph nodes. In this proposal, we intend to understand the effects of a novel tumor suppressor, Pdcd4, on colon tumor metastasis and the molecular mechanism involved in this process. This work will provide a comprehensive understanding of how Pdcd4 modulates colon tumor progression and holds great promise for novel interventions for preventing and treating colon cancer.

描述(申请人提供)：结直肠癌是美国癌症相关死亡的第二大原因，主要是由于肝脏和淋巴结的侵袭和转移。因此，对结肠癌的侵袭/转移有深入的了解对于预防和治疗结肠癌是必要的。程序性细胞死亡4(Pdcd4)是一种新的肿瘤抑制因子，过表达可抑制结肠癌细胞侵袭和AP-1依赖的转录。与癌旁正常组织相比，结肠癌组织中Pdcd4的表达经常下调。本研究的目的是明确Pdcd4在肿瘤侵袭/转移中的作用，并阐明参与这些过程的分子机制。我们下调了Pdcd4在结肠癌GEO和HT29细胞中的表达，发现Pdcd4下调可触发细胞形态变化，诱导侵袭，并激活依赖于2-catenin/Tcf和AP-1的转录。我们的初步结果进一步表明，E-钙粘蛋白表达的减少与E-钙粘蛋白表达的转录抑制因子slug的蛋白水平增加有关。因此，我们推测，Pdcd4基因敲除通过下调E-钙粘蛋白、激活2-catenin/Tcf和AP-1依赖的转录来促进结肠癌细胞的侵袭/转移。为了验证我们的假设，我们提出了四个具体目标。目的1：确定Pdcd4在结肠癌细胞中是否具有转移抑制作用。小鼠上皮到间充质的转变和转移将使用Pdcd4基因敲除和过表达的细胞进行分析。目的：研究E-钙粘素下调诱导的Pdcd4细胞2-catenin/Tcf依赖转录的激活是否促进肿瘤的侵袭和转移。我们将通过敲除E-钙粘素来检测2-连环蛋白/Tcf依赖转录的激活，通过抑制2-连环蛋白/Tcf依赖转录逆转侵袭/转移能力，验证uPAR和c-Myc作为2-连环蛋白/Tcf依赖转录的靶基因，并通过过表达Pdcd4来抑制2-连环蛋白/TCF4依赖的转录及其靶基因的表达。目的：研究Pdcd4基因敲除细胞中依赖2-catenin/TCF4的转录激活是否通过c-Myc上调MAP4K1的表达和AP-1的活性。我们将建立c-Myc作为MAP4K1表达的调节因子，并激活依赖于2-catenin/Tcf的转录，导致MAP4K1表达上调、JNK激活和AP-1依赖的转录。目的：确定Pdcd4是否在翻译上抑制转录抑制因子slug的表达，从而上调E-钙粘蛋白，抑制肿瘤的侵袭/转移。翻译抑制和抑制机制将通过体外和体内翻译试验进行分析，然后检测E-钙粘蛋白在Slug基因敲除和Pdcd4表达细胞中的表达水平和侵袭/转移能力。这项工作将提供对Pdcd4如何调控结肠癌进展的全面了解，并为预防和治疗结肠癌的新干预措施带来巨大希望。公共卫生相关性结直肠癌是美国第二大致命性癌症，主要原因是肝脏和淋巴结的侵袭和转移。在这个方案中，我们打算了解一种新的肿瘤抑制因子Pdcd4在结肠癌转移中的作用及其参与这一过程的分子机制。这项工作将提供对Pdcd4如何调控结肠癌进展的全面了解，并为预防和治疗结肠癌的新干预措施带来巨大希望。