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，也是最常见的癌症死亡原因。研究已经证实，转移性癌细胞与非转移性癌细胞在遗传学、分子组成和运动性增强方面有所不同。尽管有这些进展，但目前还没有批准的药物可用于靶向转移性癌细胞的运动。这在很大程度上是因为我们对转移细胞运动性增加背后的过程了解有限。我们最近发现，非转移细胞和转移细胞的迁移方式是完全不同的。虽然非转移细胞执行简单的扩散随机行走，但它们的转移变种不仅超扩散地移动，而且还执行所谓的L行走，其中的步长是从具有重幂定律尾部的概率分布得出的。L步道结构的特点是一簇簇的小台阶，中间偶尔有很长时间的“飞跃”。这一发现的重要性在于，从随机过程理论中可以知道，L行走代表了一种最优搜索策略--这是寻找稀有猎物的动物捕食者经常采用的一种策略。在这种背景下，转移细胞可以被视为“细胞捕食者”，以一种最大化的方式在人体内导航，以最大限度地找到合适的位置来播种转移。正如我们已经证明的，通过协同抑制Rho和Rac通路，这些L走可以恢复到纯粹的扩散走--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。我们目前的应用旨在开发概念上新的技术平台，用于定量分析转移性癌细胞的L行走运动。具体地说，微米和纳米制造以及表面功能化方案将结合起来，开发高通量细胞迁移分析，其中线性1D微轨将与96孔格式集成。将开发软件模块，使显微镜和图像采集/分析自动化，并将与基于统计物理模型的数据分析和处理相结合。一组已知或预测参与细胞迁移的50个基因-通过调节丝状肌动蛋白(F-肌动蛋白)聚合、F-肌动蛋白收缩束的形成或微管-F-肌动蛋白串扰-将被定位在聚焦的短干扰(Si)RNA屏幕上。小干扰RNA影响L步态的能力将使用全自动1DMicroTrack分析在大量细胞中进行量化。这些研究将导致发现新的调节剂和/或调节剂组合，其抑制作用可消除转移细胞L走。在这一应用背景下开发的材料系统将构成一个多功能的技术平台，可扩展到大规模RNA干扰和化学文库筛选，以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.