Role of TbRIII in Regulating Motility and Invasion

转化生长因子-<$（TGF-<$）在肿瘤发生中具有双重作用，最初作为肿瘤细胞， 抑制剂，随后作为肿瘤促进剂。在知识方面存在着根本的差距， TGF-β的二分功能机制。III型TGF-β受体（T-RIII）是一种新兴的 在调节TGF-β信号传导和致癌作用中的作用知之甚少。我们已经确定T RIII 特异性抑制癌细胞迁移和侵袭，部分通过经历胞外域脱落，释放 可溶性T <$RIII（sT <$RIII）。为了研究T <$RIII功能的机制，提出了以下假设： 细胞表面T <$RIII通过以下途径减少卵巢表面上皮细胞和卵巢癌细胞的迁移： 激活Cdc 42，破坏肌动蛋白细胞骨架，粘着斑形成，极性和抑制方向性 迁移，而通过MMP介导的胞外域脱落产生的sT <$RIII，功能是抑制TGF-β 1。 通过一种新的Smad 1通路和T <$RIII激活Cdc 42信号传导和MMP产生， 乳腺癌和卵巢癌细胞的侵袭性。这一假设将通过四个具体目标来解决。 具体目标1：T <$RIII经历胞外域脱落以产生sT <$RIII的机制将是 通过检查所涉及的蛋白酶，定义切割位点以及该过程如何 监管.具体目标2：T <$RIII抑制卵巢表面上皮细胞迁移的机制 卵巢癌细胞将通过检查T？RIII功能所需的功能元件来建立， 以及T <$RIII介导的CDC 42通路激活对极性、定向迁移、肌动蛋白 细胞骨架和局灶性复合体形成。具体目标3：T <$RIII抑制肿瘤侵袭的机制 乳腺癌和卵巢癌细胞将通过检查T <$RIII所需的功能元件来建立 功能，sT <$RIII对TGF-<$细胞表面结合的影响，通过Smad 1和MMP的TGF-<$信号传导 生产和T <$RIII介导的活化CDC 42途径对入侵的影响。目标4： 阻断T <$RIII脱落和sT <$RIII产生的作用，直接减少细胞表面T <$RIII和sT <$RIII 表达或表达T <$RIII和/或sT <$RIII对乳腺癌和卵巢癌细胞功能的影响，包括 体外增殖、凋亡、侵袭和血管生成以及体内肿瘤的形成和转移， 探索以确定细胞表面T <$RIII和sT <$RIII是否协同作用以减少乳腺癌， 卵巢癌进展。这些研究将确定T？RIII抑制乳腺癌的机制， 卵巢癌细胞的迁移和侵袭，包括胞外域脱落的作用，定义了卵巢癌的生物学特性。 在人类乳腺癌和卵巢癌的背景下，T <$RIII的胞外结构域脱落的影响，并有助于 设计预防和治疗人类乳腺癌和卵巢癌的具体干预措施， 其他人类癌症，其中T？RIII具有确定的作用。

Transforming growth factor-¿ (TGF-¿ has a dual role in tumorigenesis, initially functioning as a tumor suppressor and subsequently as a tumor promoter. A fundamental gap in knowledge exists in terms of mechanisms for the dichotomous function of TGF-¿. The type III TGF-¿ receptor (T¿RIII) has an emerging yet poorly understood role in regulating TGF-¿ signaling and carcinogenesis. We have establishing that T¿RIII specifically inhibits cancer cell migration and invasion, in part by undergoing ectodomain shedding, releasing soluble T¿RIII (sT¿RIII). To investigate the mechanism of T¿RIII function, the following hypothesis is proposed: Cell surface T¿RIII decreases the migration of ovarian surface epithelial cells and ovarian cancer cells by activating Cdc42, disrupting the actin cytoskeleton, focal adhesion formation, polarity and inhibiting directional migration, while sT¿RIII, generated through MMP-mediated ectodomain shedding, functions to inhibit TGF-¿ signaling and MMP production through a novel Smad1 pathway and T¿RIII activates Cdc42 to inhibit the invasiveness of breast and ovarian cancer cells. This hypothesis will be addressed by four Specific Aims. Specific Aim 1: The mechanism by which T¿RIII undergoes ectodomain shedding to produce sT¿RIII will be established by examining the proteases involved, defining the site(s) of cleavage and how the process is regulated. Specific Aim 2: The mechanism by which T¿RIII inhibits migration of ovarian surface epithelial cells and ovarian cancer cells will be established by examining the functional elements required for T¿RIII function, and the effect of T¿RIII-mediated activation of CDC42 pathways on polarity, directed migration, the actin cytoskeleton and focal complex formation. Specific Aim 3: The mechanism by which T¿RIII inhibits invasion of breast and ovarian cancer cells will be established by examining the functional elements required for T¿RIII function, the effect of sT¿RIII on TGF-¿ cell surface binding, TGF-¿ signaling through Smad1 and MMP production and the effect of T¿RIII-mediated activation of CDC42 pathways on invasion. Specific Aim 4: The effect of blocking T¿RIII shedding and sT¿RIII production, directly decreasing cell surface T¿RIII and sT¿RIII expression or expressing T¿RIII and/or sT¿RIII on both breast and ovarian cancer cell functions including proliferation, apoptosis, invasion and angiogenesis in vitro and tumor formation and metastasis in vivo will be explored to determine whether cell surface T¿RIII and sT¿RIII function in concert to decrease breast and ovarian cancer progression. These studies will define the mechanism by which T¿RIII inhibits breast and ovarian cancer cell migration and invasion, including the role of ectodomain shedding, define the biological implications of ectodomain shedding of T¿RIII in the context of human breast and ovarian cancers, and aid in the design of specific interventions for the prevention and treatment of human breast and ovarian cancers and other human cancers in which T¿RIII has a defined role.