Wnt Signaling in Colon Cancer

结肠癌中的 Wnt 信号转导

• 批准号: 8248742
• 负责人: Marian L Waterman
• 金额: $ 28.72万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8248742
• 关键词: Affect; Binding; Binding Sites; Biochemical; Biological; Biological Assay; Cell Culture Techniques; Cell Cycle Progression; Cell Nucleus; Cell Proliferation; Cell membrane; Cells; ChIP-seq; Colon; Colon Carcinoma; Colorectal Cancer; Complex; Consensus Sequence; DNA Binding; DNA Binding Domain; DNA Sequence; Data; Databases; Dominant-Negative Mutation; Elements; Epithelial; Epithelium; Equilibrium; Family; Family member; Funding; Gene Expression; Gene Expression Regulation; Gene Mutation; Gene Targeting; Genes; Genetic; Genome; Goals; Human; In Vitro; Intestines; Lead; Left; Length; Ligands; Link; Machine Learning; Malignant Neoplasms; Mammalian Cell; Mediating; Microarray Analysis; Modeling; Mutation; Normal Cell; Nuclear; Nuclear Export; Pathway interactions; Pattern; Phenotype; Protein Binding; Protein Isoforms; Proteins; RNA Splicing; Recruitment Activity; Response Elements; Signal Transduction; Site; Specificity; System; TCF Transcription Factor; TCF7L2 gene; Testing; Therapeutic Intervention; Tissues; autocrine; cancer cell; cancer genome; carcinogenesis; cell type; colon cancer cell line; colon carcinogenesis; expectation; extracellular; genome-wide; human disease; matrigel; member; paracrine; promoter; public health relevance; receptor; research study; tool; transcription factor; tumor initiation; tumor progression

DESCRIPTION (provided by applicant): Wnt signaling is one of the most common pathways linked to carcinogenesis in the intestine. The transcription factors that mediate Wnt signals are members of the Lymphoid Enhancer Factor/T Cell Factor (LEF/TCF) family. This four-member family is complex in that there are full-length activating forms, truncated dominant negative forms, and alternatively spliced isoforms that modify Wnt target gene recognition. TCF-1 and TCF-4 are the two family members expressed in the epithelial crypt compartment of the intestine. Normally, TCF-1 is expressed as a dominant negative isoform and it counteracts the action of TCF-4 which is expressed as a Wnt-mediating, active isoform. This pattern changes in cancer because TCF-1 expression switches to a full-length, Wnt mediating form. We have discovered a second DNA binding domain in TCF-1 and TCF-4 isoforms called the C-clamp. We have shown that the C-clamp is important for regulating cell proliferation of colon cancer cells. We have also identified Wnts that trigger TCF-1 export in colon cancer cells. Export of TCF-1 leaves the C-clamp form of TCF-4 in the nucleus to mediate aberrant Wnt signaling. Three aims are proposed for this project. First, the extracellular Wnts and intracellular components that direct TCF-1 nuclear export will be defined (Aim1). Second, the biological impact of export will be defined in colon cancer cells and colon cancer initiating 3D cultures (Aim2). Third, the DNA binding specificities and target gene selection of C-clamp forms of TCF-1 and TCF-4 will be defined through genome-wide binding assays (ChIP-Seq), high-throughput protein binding microarrays, and in vitro biochemical analysis (Aim3). The overall goal is to define the mechanisms behind changes in TCF expression in colon carcinogenesis, and to define how extracellular Wnts and DNA binding specificities of TCFs influence aberrant signaling in colon cancer cells with stabilized ?-catenin. PUBLIC HEALTH RELEVANCE: In colon cancer, Wnt signaling is an overactive and strong signal for tumor initiation and progression. Wnt signaling is mediated by the TCF transcription factors and we have discovered their activities and expression to be different in colon cancer versus normal colon tissue. This project investigates basic mechanisms of TCF localization and gene targeting and asks how differences in these attributes contribute to the cancer cell phenotype.

描述（由申请人提供）：Wnt 信号传导是与肠道致癌相关的最常见途径之一。介导 Wnt 信号的转录因子是淋巴增强因子/T 细胞因子 (LEF/TCF) 家族的成员。这个四成员家族很复杂，因为存在全长激活形式、截短的显性失活形式以及修饰 Wnt 靶基因识别的选择性剪接异构体。 TCF-1 和 TCF-4 是在肠上皮隐窝室中表达的两个家族成员。通常，TCF-1 表达为显性负亚型，它抵消 TCF-4 的作用，TCF-4 表达为 Wnt 介导的活性亚型。这种模式在癌症中发生变化，因为 TCF-1 表达转变为全长 Wnt 介导形式。我们在 TCF-1 和 TCF-4 亚型中发现了第二个 DNA 结合域，称为 C 夹。我们已经证明，C 形夹对于调节结肠癌细胞的细胞增殖很重要。我们还发现了在结肠癌细胞中触发 TCF-1 输出的 Wnt。 TCF-1 的输出在细胞核中留下 TCF-4 的 C 夹形式，以介导异常的 Wnt 信号传导。该项目提出了三个目标。首先，将定义指导 TCF-1 核输出的细胞外 Wnt 和细胞内成分（目标 1）。其次，输出的生物学影响将在结肠癌细胞和结肠癌启动 3D 培养物中定义（目标 2）。第三，TCF-1和TCF-4的C形夹形式的DNA结合特异性和靶基因选择将通过全基因组结合测定(ChIP-Seq)、高通量蛋白质结合微阵列和体外生化分析(Aim3)来确定。总体目标是确定结肠癌发生过程中 TCF 表达变化背后的机制，并确定 TCF 的细胞外 Wnt 和 DNA 结合特异性如何影响具有稳定的 β-连环蛋白的结肠癌细胞中的异常信号传导。 公共健康相关性：在结肠癌中，Wnt 信号传导是肿瘤发生和进展的过度活跃且强烈的信号。 Wnt 信号传导由 TCF 转录因子介导，我们发现它们的活性和表达在结肠癌与正常结肠组织中不同。该项目研究 TCF 定位和基因靶向的基本机制，并探讨这些属性的差异如何影响癌细胞表型。