Dissecting the opposing roles of alpha-3 integrin in metastasis

项目摘要。<$3 <$1整合素在恶性肿瘤中的作用是复杂的：虽然一些研究表明， 肿瘤抑制作用，许多其他研究表明，<$3 <$1是一个有效的促进肿瘤细胞粘附，运动 和入侵。这一悖论可能是调和的事实，除了<$3 <$1的能力，调解快速MI- 它还可以抑制促进基于E-cadherin的细胞稳定组织的信号。 粘附连接这些对立的职能之间的平衡可由以下条文规管─ 相关的四跨膜蛋白。特别是，肿瘤细胞中四跨膜蛋白CD 9的丢失与增强的肿瘤细胞增殖有关。 转移的临床和实验研究。尽管这些数据，无论是<$3 <$1功能丧失表型， 在肿瘤生物学的背景下，已经探索了3 <$1的连接稳定活性的作用。我们 长期目标是了解如何操纵肿瘤-宿主相互作用以抑制肿瘤细胞转移， 姐本申请的目的是（i）确定3 <$1整联蛋白在调节集体肿瘤中的作用， 细胞迁移、局部侵袭和转移性定植，与其 促进粘附连接的稳定性，和（ii）定义机制，通过该机制，<$3 <$1信号促进稳定， 癌细胞-细胞连接的完整性。核心假设是，3 <$1促进肿瘤侵袭的能力， 转移性定植通过<$3 <$1促进粘附连接稳定性的能力来平衡， 这取决于与四跨膜蛋白CD 9的结合。这一假设将在三个具体目标中得到检验。 第一个具体的目的是确定<$3 <$1整合素，四跨膜蛋白CD 9和<$3 <$1-CD 9联合在 促进癌细胞连接稳定性。使用表皮样癌和乳腺癌细胞， 我们将评估操纵的（i）µ 3或CD 9表达，（ii）µ 3 µ 1-CD 9结合，以及（iii）µ 3 µ 1配体结合 粘附连接的组织和稳定性，集体细胞迁移，以及完整细胞内的细胞动力学 细胞片层第二个具体目标是确定3 <$1整合素表达的作用和与 CD 9在肿瘤侵袭和转移定植中的作用我们将使用一种新的原位侵袭检测表皮 癌细胞和建立的原位自发性乳腺癌转移模型来测试肿瘤 其中<$3整合素或CD 9表达、<$3-CD 9结合或<$3配体结合已分别被 被操纵了第三个具体目标是确定信号促进粘附的机制， ens结稳定性。我们将使用我们的肿瘤细胞变体与选择性抑制剂和激活剂一起， 在我们的初步实验中确定了特异性细胞质信号效应子，以确定 在<$3 <$1信号传导和由此产生的粘附连接的稳定之间。总的来说， 这项提议有望提供关于<$3 <$1在转移性定植中的功能以及它如何 与E-cadherin的调节剂作用有关。这样的结果可能会产生关于西装的重要信息- 1整合素及其相关蛋白和下游效应物作为恶性肿瘤治疗靶点的能力。

Project Summary. The role of ¿3¿1 integrin in malignancy is complex: while some studies have indicated a tumor suppressive role, many others have shown that ¿3¿1 is a potent promoter of tumor cell adhesion, motility and invasion. This paradox may be reconciled by the fact that, in addition to ¿3¿1's ability to mediate rapid mi- gration on laminin-5, it can also transduce signals that promote the stable organization of E-cadherin-based adherens junctions. The balance between these opposing ¿3¿1 functions may be regulated by ¿3¿1- associated tetraspanin proteins. In particular, the loss of tetraspanin CD9 in tumor cells is linked to enhanced metastasis in clinical and experimental studies. Despite these data, neither the ¿3¿1 loss-of-function pheno- type nor the role of ¿3¿1's junction-stabilizing activity has been explored in the context of tumor biology. Our long term goal is to understand how tumor-host interactions can be manipulated to inhibit tumor cell metasta- sis. The objectives of this application are to (i) determine the role of ¿3¿1 integrin in regulating collective tumor cell migration, local invasion, and metastatic colonization in conjunction with, and independently of, its ability to promote adherens junction stability, and (ii) define the mechanism by which ¿3¿1 signals to promote the stabil- ity of carcinoma cell-cell junctions. The central hypothesis is that ¿3¿1's ability to promote tumor invasion and metastatic colonization is balanced by ¿3¿1's ability to promote adherens junction stability by a mechanism that depends on ¿3¿1 association with tetraspanin CD9. This hypothesis will be tested in three specific aims. The first specific aim is to determine the roles of ¿3¿1 integrin, tetraspanin CD9, and ¿3¿1-CD9 association in promoting carcinoma cell junctional stability. Using epidermoid and breast carcinoma cells in which we have manipulated (i) ¿3 or CD9 expression, (ii) ¿3¿1-CD9 association, and (iii) ¿3¿1 ligand binding, we will assess adherens junction organization and stability, collective cell migration, and the cellular dynamics within intact cell sheets. The second specific aim is to define the role of ¿3¿1 integrin expression and association with CD9 in tumor invasion and metastatic colonization. We will use a novel orthotopic invasion assay for epidermal carcinoma cells and an established orthotopic model of spontaneous breast cancer metastasis to test tumor cells in which ¿3 integrin or CD9 expression, ¿3-CD9 association, or ¿3 ligand binding have been separately manipulated. The third specific aim is to determine the mechanism by which ¿3¿1 signals to promote adher- ens junction stability. We will use our tumor cell variants together with selective inhibitors and activators of specific cytoplasmic signaling effectors identified in our preliminary experiments to determine the connection between ¿3¿1 signaling and the resulting stabilization of adherens junctions. Collectively, the experiments in this proposal are expected to provide critical data on the function of ¿3¿1 in metastatic colonization, and how it relates to ¿3¿1's role as a regulator of E-cadherin. Such results may yield important information on the suit- ability of ¿3¿1 integrin, its associated proteins, and downstream effectors as therapeutic targets in malignancy.