p120 and Kaiso dysregulation in intestinal tumorigenesis

简介(申请人提供)：结直肠癌是美国最常见的癌症之一，也是导致癌症相关死亡的第三大原因。抑癌基因APC的缺失是80%以上的肿瘤发生的始动突变，也是家族性腺瘤性息肉病(FAP)的诱因突变。APC基因产物(APC)的缺失激活了Canonical Wnt信号通路，最终导致细胞增殖、转化和肿瘤形成。使用各种不同的 在APC突变小鼠模型中，我发现APC消融与粘着连接蛋白p120-catenin(P120)的核结合伙伴Kaiso的急剧上调在时间和空间上是一致的。我们之前的数据进一步表明，在所有Wnt激活的情况下，Kaiso都有很强的核表达，因为Kaiso在肠隐窝的干细胞室自然上调，并在APC丢失或-catenin激活后异常上调。我们团队和其他人的工作进一步表明，Kaiso的这种上调可能在APC丢失引发的促肿瘤事件中发挥关键作用。基于这些观察，我的工作假设是Kaiso的表达直接或间接受到典型的Wnt途径的调控。此外，我认为Kaiso的结构性上调可能是APC缺失致癌后果的关键影响因素。以下目的试图定义Kaiso上调的机制(S)和Kaiso消融的分子后果。在目标1中，我将优化我专门设计的一种测试，以询问体内APC消融的直接物理和分子后果。这种“快速上位性分析”(以下简称REA)将在肿瘤形成的精确微环境背景下对APC消融术的效果进行有效分析。在目标2中，我将确定APC消融后Kaiso上调的机制(S)。将确定Kaiso转录、翻译和蛋白质稳定性的变化，以确定阻断Kaiso上调的方法。最后，由于Kaiso消融在ApcMin/+模型中显著延缓了肿瘤的形成，Aim 3将利用REA结合分子和形态读数来阐明导致肿瘤减弱表型(例如，细胞增殖减少，挽救细胞沿绒毛迁移，逆转去分化等)的机制(S)。Kaiso消融表型的分子效应器最终可能为药物干预提供新的靶点。

DESCRIPTION (provided by applicant): Colorectal cancer is the one of the most commonly diagnosed forms of cancer and the third leading cause of cancer-related deaths in the United States. Loss of the tumor suppressor adenomatous polyposis coli (APC) gene is the initiating mutation in ~80% of these cancers and the driving mutation behind familial adenomatous polyposis coli (FAP). Loss of the APC gene product (Apc) activates the Canonical Wnt signaling pathway, culminating in cell proliferation, transformation, and tumor formation. Using a variety of APC mutant mouse models, I have found that APC ablation coincides temporally and spatially with drastic upregulation of Kaiso, a nuclear binding partner of the adherens junction protein, p120-catenin (p120). Our previous data further show strong nuclear expression of Kaiso in all instances of Wnt activation, as Kaiso is naturally upregulated in the stem cell compartment of the intestinal crypt and aberrantly upregulated following either APC loss or -catenin activation. Work from our group and others further suggest that this upregulation of Kaiso may play a critical role in the tumor promoting events triggered by APC loss. Based on these observations, my working hypothesis is that Kaiso expression is directly or indirectly regulated by the canonical Wnt pathway. Additionally, I propose that constitutive upregulation of Kaiso may be a critical effector of the tumorigenic consequences of APC loss. The following aims seek to define the mechanism(s) of Kaiso upregulation and the molecular consequences of Kaiso ablation. In Aim 1, I will optimize an assay I have designed expressly to interrogate immediate physical and molecular consequences of APC ablation in vivo. This "Rapid Epistasis Assay" (hereafter, REA) will permit efficient analysis of the effects of APC ablation in the precise microenvironmental context of tumor formation. In Aim 2, I will identify the mechanism(s) of Kaiso upregulation following APC ablation. Alterations in Kaiso transcription, translation, and protein stability willbe determined with the goal of identifying means of blocking Kaiso upregulation. Finally, as Kaiso ablation in the ApcMin/+ model markedly delays tumor formation, Aim 3 will utilize the REA in combination with molecular and morphological readouts to clarify the mechanism(s) responsible for the tumor attenuating phenotype (e.g., reduced cell proliferation, rescued cell migration along the villus, reversal of dedifferentiation, etc.). Molecular effectors of the Kaiso ablation phenotype may ultimately provide novel targets for pharmaceutical intervention.