Transcriptional Regulation of Breast Cancer Metastasis within the Tumor Microenvi

描述（由申请人提供）：乳腺癌从原发部位逃逸导致死亡。最近，已经发现扩散所需的侵袭性肿瘤特性可以在转移性微环境内恢复以能够播种，部分地通过逆转E-钙粘蛋白的甲基化。允许乳腺癌细胞从原发性肿瘤扩散的初始间充质转化是通过EGFR家族信号传导（HER 1和HER 2）驱动的。然而，在转移播种期间，EGFR家族信号转导下调，E-钙粘蛋白重新表达。我们目前的初步数据显示，下调Kaiso，或限制Kaiso从细胞核，驱动乳腺癌细胞向分化的上皮样表型。因此，我们的转移性播种的新基础模型假定了一个关键的分子联系，使乳腺癌细胞能够纳入异位环境，甚至成为休眠状态，即保持Kaiso出核，使E-钙粘蛋白可以重新表达。在这个建议中，我们将建立转移性播种和肿瘤休眠可以最小化，如果不通过调节这个分子级联消除。要测试的目标是具体目标1。确定EGF受体信号传导如何导致Kaiso重新定位到细胞核中，以及这是否改变DNA甲基化和癌细胞表型。为此，我们将1）确定自分泌EGFR信号传导对乳腺癌中Kaiso定位/表达和E-钙粘蛋白甲基化状态的影响，和2）使用药理学和分子构建体，确定Kaiso在细胞核外隔离后的乳腺癌表型，和3）确定EGF受体信号传导/级联如何协调地改变乳腺癌细胞系中Kaiso亚细胞定位和DNA甲基化。具体目标2。1)确定Kaiso重新定位到细胞核中的破坏是否改变了进入转移性小生境和/或肿瘤休眠的发展。我们将癌细胞引入生物反应器中，并在初始转移接种期间确定Kaiso沿着E-cadherin表达的定位。（二） 确定将Kaiso定位在细胞核外对器官型肝脏微环境内肿瘤休眠的影响。3)确定核Kaiso在动物中逃离原发性肿瘤和种植转移性微环境的两个步骤中的作用。总之，通过使用原代人类外植体、已建立的细胞系和创新的人类器官型肝脏生物反应器以及动物模型，我们将确定Kaiso定位和表达水平，以及与细胞表型和细胞行为与肿瘤微环境的相关性。这些研究的成功完成将对肿瘤生物学的基础科学产生直接影响，并为乳腺癌转移和进入休眠的分子机制提供范式转变的见解，这是进展中最令人不寒而栗的方面之一。

DESCRIPTION (provided by applicant): Breast carcinoma escape from the primary site leads to mortality. Recently, it has been found that tumor properties of aggressiveness required for dissemination may revert within metastatic microenvironment to enable seeding, in part through reversal of methylation of E-cadherin. The initial mesenchymal transition that allows breast cancer cells to disseminate from the primary tumor is driven via EGFR family signaling (HER1 and HER2). However, during metastatic seeding, EGFR family signaling is downregulated and E-cadherin is re-expressed. We present preliminary data showing that downregulation of Kaiso, or restricting Kaiso from the nucleus, drives breast cancer cells towards a differentiated epithelial-like phenotype. Thus, our novel foundational model of metastatic seeding posits a key molecular link that enables the breast carcinoma cells to incorporate into the ectopic environment and even become dormant, that of retaining Kaiso out of the nucleus so that E-cadherin can be re-expressed. In this proposal we will establish that both metastatic seeding and tumor dormancy can be minimized if not eliminated by modulating this molecular cascade. The aims to be tested are Specific Aim 1. Determine how EGF receptor signaling causes relocalization of Kaiso into the nucleus and whether this alters DNA methylation and the carcinoma cell phenotype. In this aim, we will 1) Determine the influence of autocrine EGFR signaling on Kaiso localization/expression and methylation status of E-cadherin in breast cancer, and 2) Determine breast cancer phenotype upon sequestration of Kaiso outside of the nucleus, using pharmacological and molecular constructs, and 3) Determine how EGF receptor signaling/cascade coordinately alters Kaiso subcellular localization and DNA methylation in breast cancer cell lines. Specific Aim 2. 1) Determine whether disruption of Kaiso relocalization into the nucleus alters entry into the metastatic niche and/or the development of tumor dormancy. We will introduce the carcinoma cells into the bioreactor and determine the localization of Kaiso along with the expression of E-cadherin during initial metastatic seeding. 2) Determine the influence of sequestering Kaiso localization outside of the nucleus on tumor dormancy within the organotypic liver microenvironment. 3) Determine the role of nuclear Kaiso on the two steps of escape from the primary tumor and seeding of the metastatic microenvironment in animals. In summary, through the use of primary human explants, established lines, and an innovative human organotypic liver bioreactor as well as animal models, we will determine Kaiso localization and expression levels and that correlate with cell phenotype and cellular behaviors with the tumor microenvironment. Successful completion of these studies would could have immediate impact be on the basic science of tumor biology, and provide paradigm shifting insights into the molecular mechanisms by which breast carcinomas metastasize and enter dormancy, one of the most chilling aspects of progression.