Role of Slit in CXCR4-Mediated Breast Cancer Metastasis

描述(申请人提供)：趋化因子受体CXCR4及其配体CXCL12在乳腺癌转移中起关键作用。我们的初步工作表明，CXCR4介导了新的信号通路，调节CXCL12诱导的乳腺癌细胞的趋化、化学侵袭和黏附。鉴于转移是乳腺癌患者发病率和最终死亡率增加的主要原因，了解信号分子如何控制导致转移的事件具有重要意义。我们已经证明，CXCR4介导的乳腺癌细胞趋化和化学侵袭的关键调控信号分子是Cb1。这项建议的第一个具体目标是表征Cb1和CXCR4受体之间的相互作用。我们还将描述Cbl在调节CXCR4介导的趋化信号通路中的作用。此外，我们正在开发创新的策略来阻断CXCR4介导的乳腺癌细胞的转移。在这方面，我们已经证明了一种新的生物分子，称为Sit，它与Robo受体结合，阻止CXCL12诱导的趋化、化学侵袭和黏附，这些都是促进乳腺癌细胞转移的基本成分。本项目的主要目的是分析Sit作为一种抗转移因子在乳腺癌细胞中的作用。我们假设：1)Sit治疗将抑制乳腺癌细胞向肺部和淋巴结的转移；2)Sit诱导Robo和CXCR4受体之间的串扰；3)Sit通过阻断RAFTK/Pyk2和β-catenin的功能来抑制金属蛋白酶的分泌。为了验证这些假说，我们将分析Sit和Robo分子中介导抗转移功能的调节区。在目标2中，我们将研究不同截短的狭缝分子对不同乳腺癌细胞的趋化、化学侵袭和黏附特性的影响。在体外鉴定后，我们将在体内模型系统中研究Sit及其截断形式在乳腺癌转移发病机制中的体内作用。在目标3中，我们将定义与CXCR4受体相互作用的Robo受体细胞质尾部的结构域。我们还将研究截短形式的Robo受体在乳腺癌转移中的作用。在这一目标中，我们还将确定RAFTK/Pyk2和β-catenin在Sit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CXCL12诱导的和缝隙介导的趋化/化学侵袭通路，这些通路可能成为治疗乳腺癌转移的新靶点。此外，基于对Sit/Robo功能的研究，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.