Microsystems for targeting Levy walks in metastatic cancer cells

描述（由申请人提供）：细胞迁移是转移的标志，是癌症最常见的死亡原因。研究已经证实，转移性癌细胞与非转移性癌细胞在遗传、分子组成和运动性增加方面有所不同。尽管取得了这些进展，但目前还没有批准的针对转移性癌细胞运动的药物。这在很大程度上是由于我们对转移细胞运动增强背后的过程了解有限。我们最近表明，非转移性和转移性细胞以根本不同的方式迁移。当非转移细胞执行简单的扩散随机游动时，它们的转移变体不仅超扩散地移动，而且还执行所谓的L¿vy游动，其中步长是从具有重幂律尾部的概率分布中绘制的。L¿vy步行路径结构的特点是由偶尔但长时间的“飞行”分开的小台阶集群。这一发现的重要性在于，从随机过程理论可知，L¿vy行走代表了一种最优搜索策略——一种经常被动物捕食者用来寻找稀缺猎物的策略。在这种情况下，转移细胞可以被视为“细胞捕食者”，以最大限度地找到合适的转移位点的方式导航人体。正如我们所展示的那样，通过协同抑制Rho和Rac途径，这些L - vy行走可以恢复为纯粹的弥漫性行走——这一发现为合理控制并最终限制转移细胞的“掠夺性”行走铺平了道路。我们目前的申请旨在开发概念上新颖的技术平台，用于定量分析转移癌细胞的L - vy运动。具体来说，微纳米加工和表面功能化方案将结合起来开发高通量细胞迁移试验，其中线性1D微轨道将与96孔格式集成。软件模块将被开发用于自动化显微镜和图像采集/分析，并将与基于统计物理模型的数据分析和处理相连接。一组已知或预计参与细胞迁移的50个基因——通过调节丝状肌动蛋白（F-actin）聚合、F-actin收缩束的形成或微管- F-actin串扰——将成为聚焦短干扰（si） RNA筛选的目标。sirna影响L - vy行走的能力将使用全自动1D微迹分析在大量细胞中进行量化。这些研究将导致鉴定新的调节剂和/或调节剂组合，其抑制消除转移细胞的L - vy行走。在此应用背景下开发的材料系统将构成一个通用的技术平台，可扩展到大规模RNA干扰和化学文库筛选，用于发现新的药物靶点和抗运动/抗转移药物。

DESCRIPTION (provided by applicant): Cell migration is a hallmark of metastasis, a most common cause of death from cancer. Research has established that metastatic cancer cells differ from the non-metastatic ones in terms of their genetics, molecular composition, and increased motility. Despite these advances, there are currently no approved drugs available that target motility of metastatic cancer cells. This is in large part due to our limited understanding f what processes underlie the increased motility of the metastatic cells. We have recently shown that non- metastatic and metastatic cells migrate in fundamentally different ways. While non-metastatic cells execute simple, diffusive random walks, their metastatic variants move not only superdiffusively, but also perform so-called L¿vy walks in which step-times are drawn from probability distributions with heavy power-law tails. L¿vy walk path structure is characterized by clusters of small steps separated by occasional but long "flights". The importance of this finding is that it is known from the theory of stochastic processes that L¿vy walks represent an optimal search strategy - one that is often employed by animal predators looking for scarce prey. In this context, metastatic cells can be viewed as "cellular predators" navigating human body in a manner that maximizes their chances of finding suitable loci for seeding metastases. As we have showed, these L¿vy walks can be reverted to the purely diffusive walks by synergistic inhibition of Rho and Rac pathways - this finding paves the way to rationally controlling and ultimately limiting the "predatory" walks of metastatic cells. Our current application aims to develop conceptually novel technological platform for quantitative analysis of L¿vy walk motility of metastatic cancer cells. Specifically, micro- and nanofabrication and surface functionalization schemes will be combined to develop high-throughput cell migration assay in which linear 1D microtracks will be integrated with 96-well format. Software modules will be developed to automate the microscopy and image acquisition/analysis and will be interfaced with data analyses and processing based on statistical-physical models. A set of 50 genes known or predicted to be involved in cell migration - by regulating filamentous actin (F-actin) polymerization, formation of F-actin contractile bundles or microtubule-F- actin crosstalk - will b targeted in a focused short interfering (si) RNA screen. The ability of siRNAs to affect L¿vy walks will be quantified over large populations of cells using the fully automated 1D microtrack assay. These studies will result in the identification of novel regulators and/or regulator combinations whose inhibition abrogates metastatic cell L¿vy walks. The material systems developed in the context of this application will constitute a versatile technological platform extendable to large scale RNA interference and chemical library screens for the discovery of new drug targets and anti-motility/ anti-metastasis drugs. PUBLIC HEALTH RELEVANCE: We have recently discovered that as cancer cells metastasize, they develop the so-called L¿vy walking navigation strategy typically used by animal predators searching for scarce resources. This skillful mode of cell motility can help the metastatic cells to seed new tumors. The research we propose aims at the development of technology with which to (i) study this "predatory" mode of cell motility in analytical precision; and (ii) facilitate the discovery of proteins whose inhibition would revert the metastatic L¿vy walkers into "benign," diffusive cells.