Novel Mechanisms of Carcinoma Cell Migration

描述(申请人提供)：肿瘤侵袭和转移仍然夺走了大多数癌症患者的生命。尽管在癌症检测和预防方面取得了长足的进步，但对癌症转移的更有效治疗的需要仍然是一个中心问题。值得注意的是，控制细胞极化和定向迁移的空间信号的分子通过提高转移第一步的效率而导致癌症的致命性。RhoA在定向细胞运动过程中促进细胞极化，但 RhoA是如何在空间上受到控制的仍不清楚。我们认为整合素信号通过cAMP/PKA参与RhoA的空间信号传递和细胞极化。重要的是，我们之前的工作表明，整合素控制着在癌细胞前沿的PKA活性梯度的产生，在那里它控制着RhoA的功能。我们提供了令人信服的证据，证明这些PKA活性梯度存在于乳腺癌患者样本和三维乳腺癌培养中，这证明了这些梯度在人类乳腺癌中的重要性。整合素β6？4在晚期乳腺癌中表达上调，与基底细胞样乳腺癌关系最为密切。重要的是，整合素？6？4通过一种我们提出的逆转PKA作用的机制来促进RhoA的激活。因此，我们认为，这些整合素对RhoA的反向调节模式允许RhoA的有效区隔，从而促进乳腺癌的运动、侵袭和转移。因此，这一应用的中心假设是1整合素和整合素6 4之间的协同信号促进了RhoA活性的空间分布，从而促进了片层的形成和定向迁移。我们小组的长期目标是确定整合素如何促进肿瘤的侵袭，以便它们最终可能被适当地作为治疗干预的靶点，特别强调整合素？6？4。我们将测试我们的中心假设，并通过完成以下目标来实现我们的长期目标：1)定义将整合素偶联到PKA激活的大分子复合体，从而限制前沿的RhoA活性，2)确定整合素？6？4如何导致RhoA的激活，以及3)阐明RhoA功能如何改变以促进片层形成。我们非常适合进行这些研究，因为我们有强大的合作关系；我们依赖整合素和RhoA的侵袭和迁移的模型具有良好的特性；我们在整合素生物学和Rho信号方面的专业知识，以及我们支持该项目的坚实的初步数据。这项研究的结果将是重要的，因为他们将深入到关于整合素如何协调空间信号以实现极化、板层形成、定向细胞迁移以及最终侵袭的机械性深度。最终，我们的研究将具有重要意义，因为它将产生对控制前沿动力学的信号通路的更坚定的理解，这些前沿动力学将产生成功的方法来针对转移的早期步骤进行治疗。

DESCRIPTION (provided by applicant): Tumor invasion and metastasis still claim the majority of cancer patients' lives. Although great strides have been made in cancer detection and prevention, the need for a more effective treatment for cancer metastasis remains a central problem. Notably, molecules that control spatial signaling for cell polarization and directed migration contribute to the lethality of cancer through their ability to improve the efficiency of he first steps of metastasis. RhoA contributes to cell polarization during directed cell motility, yet how RhoA is spatially controlled remains unclear. We propose that integrin signaling through cAMP/PKA is instrumental for spatial signaling of RhoA and cell polarization. Importantly, our previous work has shown that ?1 integrins control the generation of PKA activity gradients at the leading edge of migrating carcinoma cells where it controls RhoA function. We provide compelling evidence that these PKA activity gradients exist in breast carcinoma patient samples and in three-dimensional breast carcinoma cultures, which attest to the significance of these gradients in human breast cancer. Integrin??6?4 is upregulated in advanced breast cancers where it is most closely associated with basal-like breast cancers. Importantly, integrin ??6?4 promotes the activation of RhoA by a mechanism that we propose reverses the effect of PKA. Therefore, we suggest that the counter-opposing modes of regulation these integrins have on RhoA permit efficient compartmentalization of RhoA that facilitates breast carcinoma motility, invasion and metastasis. Accordingly, the central hypothesis of this application is that cooperative signaling between ?1 integrins and integrin ?6?4 facilitates the spatial distribution of RhoA activity to promote lamellae formation and directed migration. The long-term goal of our group is to determine how integrins contribute to tumor invasion so that they may be eventually targeted appropriately for therapeutic intervention, with special emphasis on integrin ?6?4. We will test our central hypothesis and achieve our long- term goal through the completion of the following aims: 1) Define the macromolecular complex that couples ?1 integrins to PKA activation thereby limiting RhoA activity at the leading edge, 2) Determine how integrin ?6?4 leads to the activation of RhoA, and 3) Elucidate how RhoA function is altered to promote lamellae formation. We are uniquely suited to perform these studies due to our strong collaborations; our well-characterized models of ?6?4 integrin- and RhoA-dependent invasion and migration; our expertise in integrin biology and Rho signaling, and our solid preliminary data supporting this project. The results obtained from this study will be important as they will go int mechanistic depth regarding how integrins coordinate spatial signaling to achieve polarization, lamellae formation, directed cell migration and, finally, invasion. Ultimately, our study will be significant as it will generate a firmer understanding of signaling pathways that govern leading edge dynamics that will produce successful methods to therapeutically target the early steps in metastasis.