Effects of fluid shear stress on circulating tumor cells

 描述(申请人提供)：癌症患者的远处转移是由于癌细胞逃离原发肿瘤并通过血流转移到次要器官部位。关于这一旅程如何影响这些循环中的肿瘤细胞(CTCs)的生物学，人们知之甚少。在血液中，CTCs暴露在来自上皮器官的癌细胞所不具备的血液动力中。最近有研究表明，与正常或良性上皮细胞相比，来自多种上皮组织的癌细胞株对高水平流体切应力(FSS)的短暂脉冲具有获得性抵抗力。这种表型至少通过几条常见的致癌途径反映了信号传递。这项建议的目的是阐明癌细胞中FSS耐药的机制(S)，并利用人体心脏模型和前列腺癌转移小鼠模型测量CTC中FSS耐药的情况，以更好地了解CTCs在循环中经历FSS的方式。这一提议的中心假设是，循环中的癌细胞暴露在高水平FSS的短暂脉冲中，触发膜-细胞骨架变化，从而对FSS产生抵抗。这项拟议研究的基本原理是，它将首次阐明癌细胞对FSS的反应，以及这与CTCs在血流动力学力量中生存的能力有何关系。这项建议的具体目的是：1)确定癌细胞中FSS耐药的机制。根据我们的初步数据，我们的工作假设是，暴露于FSS可通过受损的质膜诱导钙内流。这触发质膜修复以及依赖于Rho的肌动蛋白细胞骨架的调制，使细胞对随后暴露于FSS具有抵抗力；以及2)测量生理性FSS对癌细胞的影响。根据我们对短脉冲高水平FSS对癌细胞影响的观察，我们的工作假设是，CTCs在生理环境中也经历这些力，并表现出FSS抗性。我们将使用一种精确模拟人类心脏的设备来确定暴露在高水平剪应力的短暂脉冲中是否会触发癌细胞的FSS耐药性，我们将测量小鼠血液样本中CTCs的FSS耐药性。这一建议的贡献将是重大的，因为它将开始阐明癌细胞如何对流体剪应力做出反应的机制，并确定CTCs在生理环境下是否表现出FSS耐药。阐明FSS耐药的机制可能对诊断方法有意义，例如，将FSS作为区分良恶性细胞的一种手段。同样，这些研究可能为通过干扰FSS耐药来降低转移潜能的治疗方法提供参考。这项拟议的研究在概念上是创新的，因为它挑战了通常持有的观点，即CTCs本质上是脆弱的，非常容易受到血流动力学剪切力的破坏，技术上也是创新的，因为我们将使用一种装置来概括人类心脏中的生理性剪应力，以探索FSS对癌细胞的影响。

 DESCRIPTION (provided by applicant): Distant metastasis in cancer patients results from cancer cells escape from a primary tumor and travel through the bloodstream to secondary organ sites. Little is known about how this journey affects the biology of these circulating tumor cells (CTCs). Within the bloodstream, CTCs are exposed to hemodynamic forces which are foreign to cancer cells derived from epithelial organs. It has recently been shown that cancer cell lines from numerous epithelial tissues exhibit an acquired resistance to brief pulses of high level fluid shear stress (FSS) compared to normal or benign epithelial cells. This phenotype reflects signaling through at least several common oncogenic pathways. The objective of this proposal is to elucidate the mechanism(s) underlying FSS-resistance in cancer cells and to gain a greater understanding of how CTCs experience FSS in circulation using a model of the human heart and measuring FSS-resistance in CTCs from a mouse model of prostate cancer metastasis. The central hypothesis of this proposal is that cancer cells in the circulation are exposed to brief pulses of high-level FSS that trigger membrane-cytoskeletal changes which confer resistance to FSS. The rationale for the proposed research is that it will for the first tim elucidate how cancer cells respond to FSS, and how this relates to the ability of CTCs to survive hemodynamic forces. The specific aims of this proposal are: 1) Determine the mechanisms underlying FSS resistance in cancer cells. Based on our preliminary data, our working hypothesis is that exposure to FSS induces calcium entry through damaged plasma membrane. This triggers plasma membrane repair as well as Rho-dependent modulation of the actin cytoskeleton which renders cells resistant to subsequent exposure to FSS; and 2) Measure the effects of physiologic FSS on cancer cells. Based on our observations on the effects of brief pulses of high level FSS on cancer cells, our working hypothesis is that CTCs also experience these forces in physiologic settings and exhibit FSS resistance. We will employ a device that accurately models the human heart to determine if exposure to brief pulses of high-level shear stress triggers FSS resistance in cancer cells and we will measure FSS resistance in CTCs in blood samples from mice. The contribution of this proposal will be significant because it will begin to elucidate the mechanisms for how cancer cells respond to fluid shear stress and to determine if CTCs exhibit FSS resistance under physiological settings. Elucidating the mechanisms underlying FSS-resistance may have implications for diagnostic approaches, for instance, by using FSS as a means to distinguish benign from malignant cells. Likewise, these studies may inform therapeutic approaches to reduce metastatic potential by interfering with FSS-resistance. The proposed research is conceptually innovative because it challenges the commonly held idea that CTCs are intrinsically fragile and highly subject to destruction from hemodynamic shear forces and technically innovative because we will use a device that recapitulates physiologic shear stress in the human heart to explore the effects of FSS in cancer cells.