Novel Mechanisms of Carcinoma Cell Migration

描述（申请人提供）：肿瘤侵袭和转移仍然夺去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巨大进步，但对癌症转移更有效的治疗的需求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传导的分子通过提高转移第一步的效率而有助于癌症的致死率。 RhoA 在定向细胞运动过程中有助于细胞极化，但 RhoA 是如何在空间上受控的仍不清楚。我们认为通过 cAMP/PKA 的整合素信号传导有助于 RhoA 的空间信号传导和细胞极化。重要的是，我们之前的工作表明，α1 整合素控制迁移癌细胞前缘 PKA 活性梯度的产生，并控制 RhoA 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物中，这证明了这些梯度在人类乳腺癌中的重要性。整合素??6?4 在晚期乳腺癌中表达上调，与基底样乳腺癌关系最为密切。重要的是，整合素??6?4 通过我们提出的逆转 PKA 作用的机制促进 RhoA 的激活。因此，我们认为这些整合素对 RhoA 的相反调节模式允许 RhoA 的有效区室化，从而促进乳腺癌的运动、侵袭和转移。因此，本申请的中心假设是α1整联蛋白和整联蛋白α6β4之间的协同信号传导促进RhoA活性的空间分布，从而促进片层形成和定向迁移。我们小组的长期目标是确定整合素如何促进肿瘤侵袭，以便最终可以适当地针对它们进行治疗干预，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α1整合素与PKA激活偶联的大分子复合物，从而限制前沿的RhoA活性，2）确定整合素α6α4如何导致RhoA激活，以及3）阐明如何改变RhoA功能以促进薄片形成。由于我们强有力的合作，我们非常适合开展这些研究；我们充分表征的 6?4 整合素和 RhoA 依赖性入侵和迁移模型；我们在整合素生物学和 Rho 信号传导方面的专业知识，以及支持该项目的可靠初步数据。这项研究获得的结果非常重要，因为它们将深入探讨整合素如何协调空间信号传导以实现极化、片层形成、定向细胞迁移以及最终入侵的机制。最终，我们的研究将具有重要意义，因为它将对控制前沿动态的信号通路产生更坚定的理解，从而产生成功的方法来治疗转移的早期步骤。

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.