Effects of fluid shear stress on circulating tumor cells

 描述（由申请人提供）：癌症患者的远处转移是由于癌细胞从原发性肿瘤中逃逸并通过血流到达继发性器官部位。关于这一过程如何影响这些循环肿瘤细胞（CTC）的生物学，人们知之甚少。在血流内，CTC暴露于血液动力学力，其对于源自上皮器官的癌细胞是外来的。最近已经表明，与正常或良性上皮细胞相比，来自许多上皮组织的癌细胞系表现出对高水平流体剪切应力（FSS）的短暂脉冲的获得性抗性。这种表型反映了通过至少几种常见致癌途径的信号传导。本提案的目的是阐明癌细胞中FSS抗性的潜在机制，并使用人类心脏模型和测量来自前列腺癌转移小鼠模型的CTC中的FSS抗性来更好地理解CTC如何在循环中经历FSS。该建议的中心假设是，循环中的癌细胞暴露于高水平FSS的短暂脉冲，其触发赋予对FSS的抗性的膜细胞骨架变化。这项研究的基本原理是，它将首次阐明癌细胞如何对FSS作出反应，以及这与CTC在血流动力学力量下生存的能力如何相关。该提案的具体目标是：1）确定癌细胞中FSS抗性的潜在机制。基于我们的初步数据，我们的工作假设是，暴露于FSS诱导钙通过受损的质膜进入。这触发质膜修复以及肌动蛋白细胞骨架的Rho依赖性调节，这使得细胞对随后暴露于FSS具有抗性;和2）测量生理性FSS对癌细胞的影响。基于我们对高水平FSS的短脉冲对癌细胞的影响的观察，我们的工作假设是CTC在生理环境中也经历这些力并表现出FSS抗性。我们将采用一种精确模拟人类心脏的设备，以确定暴露于高水平剪切应力的短暂脉冲是否会触发癌细胞的FSS抗性，我们将测量小鼠血液样本中CTC的FSS抗性。该提议的贡献将是显著的，因为它将开始阐明癌细胞如何响应流体剪切应力的机制，并确定CTC是否在生理环境下表现出FSS抗性。阐明FSS耐药性的机制可能对诊断方法有影响，例如，通过使用FSS作为区分良性和恶性细胞的手段。同样，这些研究可能会为通过干扰FSS耐药性来降低转移潜力的治疗方法提供信息。拟议的研究在概念上是创新的，因为它挑战了普遍持有的观点，即CTC本质上是脆弱的，并且极易受到血流动力学剪切力的破坏，并且在技术上是创新的，因为我们将使用一种能够重现人类心脏中生理剪切力的设备来探索FSS在癌细胞中的作用。

 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.