Mechanisms of Tumorigenesis in Pancreatic Epithelial Cells

胰腺上皮细胞肿瘤发生机制

• 批准号: 7116294
• 负责人: PAUL J CHIAO
• 金额: $ 18.9万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7116294
• 关键词: RNA interference; adenocarcinoma; athymic mouse; cell adhesion; cell line; epithelium; gene induction /repression; metastasis; molecular oncology; neoplasm /cancer genetics; neoplastic transformation; nuclear factor kappa beta; oncoproteins; pancreas neoplasms; phenotype; posttranslational modifications; protein structure function

DESCRIPTION (provided by applicant): Pancreatic adenocarcinoma is the fourth leading cause of adult cancer mortality in the United States. The five-year survival rate continues at 1-3%. At the time of diagnosis, most pancreatic cancer patients present with advanced and metastatic disease. Although a genetic profile for pancreatic caner is emerging, it is still unknown how these genetic alterations elicit the unique phenotypes and clinical course of pancreatic cancer. The underlying mechanisms, by which pancreatic epithelial cells become tumorigenic, invasive and metastatic, remain to be elucidated. The advance in understanding of the molecular basis of pancreatic cancer is hindered in part due to the lack of normal human pancreatic ductal epithelial cells for analyzing the role of genetic alterations in tumorigenesis and metastasis, and experimental animal models that recapitulate the molecular pathogenesis and tumor biology of this disease. Therefore, the long-term objective of the proposed research is study the molecular basis of pancreatic tumorigenesis and metastasis using an E6E7-immortalized human pancreatic ductal epithelial (HPDE/E6E7) cells that carry the signature genetic alterations in this disease, and determine the phenotypes induced by these genetic alterations using an orthotopic mouse model. The recent findings show that: (1) mutated K-ras4B (G12V) transformed HPDE/E6E7 and induced weak tumorigenicity in orthotopic mouse model; (2) the K-ras downstream target genes were identified; (3) the mutant IkappaBalpha (S32, 36A) mediated inhibition of constitutive NF-kappaB activation suppressed liver metastasis of pancreas cancer cells in an orthotopic nude mouse model; (4) overexpression of Smad4 inhibits tumorigenesis of pancreatic cancer cell lines. The hypothesis, activation of K-ras and NF-kappaB, or inactivation of Smad4 induces tumorigenic or metastatic phenotype by altering the expression of their downstream target genes in immortalized human pancreatic ductal epithelial cells, will be tested. The specific aims are: (1) Study the mechanism of K-ras induced oncogenic transformation of HPDE/E6E7 cells (2) Determine the function of constitutively activated NF-kappaB in induction of metastasis. (3) Determine the role of Smad4 in initiating tumorigenic and metastatic phenotypes in HPDE/E6E7 cells. Generation of various cell lines that carry the signature mutation of pancreatic cancer should permit the identification of the genetic alterations required in concert to induce tumorigenic and metastatic phenotype of this disease. Furthermore, mechanisms underlying tumor progression, including genomic instability and alterations in signal cascades associated with these pancreatic cancer signature mutations can be analyzed in a relevant in vivo and in vitro context using molecular and biochemical methods. A better understanding of the mechanisms of genetic alterations in induction of tumorigenic and metastatic phenotypes will provide a basis for developing early detection and effective treatment strategies for pancreatic cancer.

描述（由申请人提供）：胰腺腺癌是美国成人癌症死亡率的第四大原因。五年生存率持续在 1-3%。在诊断时，大多数胰腺癌患者已处于晚期和转移性疾病。尽管胰腺癌的基因谱正在出现，但仍不清楚这些基因改变如何引发胰腺癌的独特表型和临床病程。胰腺上皮细胞致瘤、侵袭和转移的潜在机制仍有待阐明。对胰腺癌分子基础的理解进展受到阻碍，部分原因是缺乏正常人胰腺导管上皮细胞来分析遗传改变在肿瘤发生和转移中的作用，以及概括分子发病机制和肿瘤生物学的实验动物模型这种疾病。因此，本研究的长期目标是使用 E6E7 永生化人胰腺导管上皮 (HPDE/E6E7) 细胞研究胰腺肿瘤发生和转移的分子基础，该细胞携带该疾病的标志性遗传改变，并确定表型使用原位小鼠模型通过这些基因改变诱导。最近的研究结果表明：（1）突变的K-ras4B（G12V）转化HPDE/E6E7并在原位小鼠模型中诱导弱致瘤性； (2)K-ras下游靶基因的鉴定； (3)在原位裸鼠模型中，突变型IkappaBalpha (S32, 36A)介导的对NF-kappaB组成型激活的抑制抑制了胰腺癌细胞的肝转移； (4)Smad4的过表达抑制胰腺癌细胞系的肿瘤发生。 K-ras 和 NF-kappaB 的激活或 Smad4 的失活通过改变其下游靶基因在永生化人胰腺导管上皮细胞中的表达来诱导致瘤或转移表型的假设将得到测试。具体目的是：（1）研究K-ras诱导HPDE/E6E7细胞致癌转化的机制。（2）确定组成型激活的NF-kappaB在诱导转移中的功能。 (3)确定Smad4在HPDE/E6E7细胞中启动致瘤和转移表型中的作用。携带胰腺癌特征突变的各种细胞系的产生应该能够鉴定出诱导该疾病的致瘤和转移表型所需的基因改变。此外，可以使用分子和生化方法在相关的体内和体外环境中分析肿瘤进展的机制，包括基因组不稳定性和与这些胰腺癌特征突变相关的信号级联的改变。更好地了解遗传改变诱导致瘤和转移表型的机制将为开发胰腺癌的早期检测和有效治疗策略提供基础。