Role of Slit in CXCR4-Mediated Breast Cancer Metastasis

描述（由申请人提供）：趋化因子受体CXCR 4及其配体CXCL 12在乳腺癌转移中起关键作用。 我们的初步工作表明，CXCR 4介导的新的信号通路，调节CXCL 12诱导的趋化性，化学侵袭，乳腺癌细胞的粘附。 鉴于转移作为乳腺癌患者发病率和最终死亡率增加的主要原因的重要性，了解信号分子如何控制导致转移的事件具有根本重要性。 我们已经表明，一个关键的调节信号分子CXCR 4介导的乳腺癌细胞的趋化性和化学侵袭是Cbl。 该提议的第一个具体目的是表征Cbl和CXCR 4受体之间的相互作用。 我们还将描述Cbl在调节CXCR 4介导的趋化信号通路中的作用。 此外，我们正在开发创新策略来阻断CXCR 4介导的乳腺癌细胞转移。 在这方面，我们已经证明，一种与Robo受体结合的新型生物分子，称为Slit，可以阻断CXCL 12诱导的趋化性，化学侵袭和粘附，这些是促进乳腺癌细胞转移的基本成分。 该项目的主要目的是分析Slit作为乳腺癌细胞中抗转移因子的作用。 我们假设：1）Slit治疗将抑制乳腺癌细胞转移到肺和淋巴结; 2）Slit诱导Robo和CXCR 4受体之间的串扰;和3）Slit通过阻断RAFTK/Pyk 2和β-连环蛋白的功能来抑制金属蛋白酶分泌。 为了验证这些假设，我们将分析介导抗转移功能的Slit和Robo分子内的调控区域。 在目标2中，我们将研究不同截短的Slit分子在各种乳腺癌细胞的趋化性、化学侵袭性和粘附性中的作用。 在体外表征后，我们将在体内模型系统中研究Slit及其截短形式对乳腺癌转移发病机制的体内作用。 在目标3中，我们将定义与CXCR 4受体相互作用的Robo受体胞质尾区的结构域。 我们还将研究截短形式的Robo受体对乳腺癌转移的影响。 在这个目标中，我们还将确定RAFTK/Pyk 2和β-连环蛋白在Slit介导的基质金属蛋白酶2和9分泌下调以及其他抗趋化和化学侵袭机制中的作用。 这些研究将帮助我们确定CXCL 12诱导的和Slit介导的趋化/化学侵袭途径，这些途径可能成为治疗乳腺癌转移的新靶点。 此外，基于Slit/Robo功能的这些研究，可以预期预防乳腺癌转移的创新治疗策略。

DESCRIPTION (provided by applicant): The chemokine receptor CXCR4 and its ligand CXCL12 play a critical role in breast cancer metastasis. Our preliminary work indicates that CXCR4 mediates novel signaling pathways that regulate the CXCL12-induced chemotaxis, chemoinvasion, and adhesion of breast cancer cells. Given the importance of metastasis as the major cause of increased morbidity and eventual mortality in breast cancer patients, understanding of how signaling molecules control the events that lead to metastasis is of fundamental importance. We have shown that a key regulatory signaling molecule linked to CXCR4-mediated breast cancer cell chemotaxis and chemoinvasion is Cbl. The first specific aim of this proposal is to characterize the interaction between Cbl and the CXCR4 receptor. We will also characterize the role of Cbl in modulating CXCR4-mediated chemotactic signaling pathways. Moreover, we are developing innovative strategies to block the CXCR4-mediated metastasis of breast cancer cells. In this regard, we have shown that a novel biological molecule that binds to the Robo receptor, called Slit, blocks CXCL12-induced chemotaxis, chemoinvasion and adhesion, the fundamental components that promote the metastasis of breast cancer cells. The main objective of this project is to analyze the role of Slit as an anti-metastatic factor in breast cancer cells. We hypothesize that: 1) Slit treatment will inhibit breast cancer cell metastasis to the lungs and lymph nodes; 2) Slit induces cross-talk between Robo and the CXCR4 receptor; and 3) Slit inhibits metalloproteinase secretion by blocking the functions of RAFTK/Pyk2 and beta-catenin. To test these hypotheses, we will analyze the regulatory region within the Slit and Robo molecules that mediate anti-metastatic functions. In Aim 2, we will study the effects of different truncated Slit molecules in the chemotaxis, chemoinvasion, and adhesive properties of various breast cancer cells. After in vitro characterization, we will study the in vivo effects of Slit and its truncated form on the pathogenesis of breast cancer metastasis in an in vivo model system. In Aim 3, we will define the domain on the cytoplasmic tail of this Robo receptor that interacts with the CXCR4 receptor. We will also study the effect of the truncated form of the Robo receptor on breast cancer metastasis. In this aim, we will also define the role of RAFTK/Pyk2 and beta-catenin on the Slit-mediated downregulation of matrix-metalloproteinase 2 and 9 secretion and other anti-chemotactic and chemoinvasive mechanisms. These studies will help us to identify CXCL12-induced and Slit-mediated chemotactic/chemoinvasive pathways that may become novel targets for the treatment of breast cancer metastasis. Furthermore, innovative therapeutic strategies to prevent breast cancer metastasis can be anticipated based on these studies of Slit/Robo function.