The Role of Physical Cues in Collective Cell Invasion

项目1：物理线索在集体细胞入侵中的作用 肿瘤侵袭邻近组织的能力，导致局部或远处转移，是癌症的标志。 癌细胞经常作为粘附细胞群在称为集体侵袭的过程中侵袭。先前 研究主要集中在单细胞或半集体（多细胞流）细胞侵袭上。单个 用于转移的细胞模型对于细胞作为个体组成性迁移的肿瘤具有直接意义 细胞，如白血病和淋巴瘤，或在细胞通过上皮细胞- 间充质转化（EMT）。然而，EMT长期以来在病理学家中一直存在争议， 转移部位的肿瘤通常显示上皮特征。虽然可以观察到EMT样基因特征， 在特定的小鼠模型和乳腺癌亚型中，大多数乳腺肿瘤没有表现出明显的 EMT的分子特征活体显微镜研究显示肿瘤细胞优先迁移 共同地沿着由体内各种解剖结构限定的预先存在的通道。但据 目前还不知道微环境的物理性质，例如限制和顺应性， 调节集体细胞入侵的分子机制。有趣的初步数据显示， 细胞作为一个集体单位通过宽的（≥50 µm）轨迹迁移。然而，随着限制的增加，癌症 细胞自发扩散，首先为2-5个细胞的簇，最终以非常窄的轨道（≤10 µm）， 单细胞我们假设物理微环境诱导了一系列事件的信号级联， 将经典的集体侵袭转化为单细胞侵袭。为了验证这一假设，我们将使用 多学科方法结合了新颖的生物工程工具和数学建模， 分子细胞生物学和成像技术以及体内模型。在目标1中，我们将制定一个综合的 有限几何形状中细胞集体运动的实验和计算模型 肿瘤的侵袭，并剖析机制，其中细胞与细胞接触是在机械诱导释放 过渡到单细胞运动，重点是E-钙粘蛋白裂解和可能的EMT诱导的作用。在 目标2，我们将描述肌动球蛋白收缩性、小GTPases和渗透压的相对贡献 引擎模型在刚性与柔性受限微环境中的运动。在目标3中，我们将验证 我们在体外对癌细胞的传播和运动的理解， 使用器官型3D培养系统的体内乳腺肿瘤的微环境特征， 基因工程小鼠模型。阐明集体癌细胞的潜在机制 入侵将为我们了解癌细胞如何在体内扩散提供见解， 改变目前在癌症中流行的单细胞范例以纳入机械信号传导的概念， 细胞-细胞粘附和细胞-细胞协作。

Summary of Project 1: The Role of Physical Cues in Collective Cell Invasion The ability of tumors to invade adjacent tissues, leading to local or distant metastasis, is a hallmark of cancer. Cancer cells frequently invade as groups of adherent cells in a process termed collective invasion. Previous studies have primarily focused on single cell or semi-collective (multicellular streaming) cell invasion. Single cell models for metastasis have direct implications for tumors whose cells migrate constitutively as individual cells, such as leukemias and lymphomas, or after cell detachment from a primary tumor via epithelial-to- mesenchymal transition (EMT). However, EMT has long been controversial among pathologists as breast tumors at metastatic sites typically display epithelial features. While EMT-like gene signatures can be observed in specific mouse models and breast cancer subtypes, the majority of breast tumors do not exhibit clear molecular features of EMT. Intravital microscopy studies reveal that tumor cells preferentially migrate collectively along pre-existing channels that are defined by various anatomical structures in vivo. However, it is currently unknown how the physical properties of the microenvironment, such as confinement and compliance, regulate the molecular mechanisms of collective cell invasion. Intriguing preliminary data reveal that cancer cells migrate through wide (≥50 µm) tracks as a collective unit. However, as confinement increases, the cancer cells spontaneously disseminate, first as clusters of 2-5 cells and eventually, in very narrow tracks (≤10 µm), as single cells. We hypothesize that the physical microenvironment induces a signaling cascade of events that transforms the classical collective to single cell invasion. To test this hypothesis, we will employ a multidisciplinary approach combining novel bioengineering tools and mathematical modeling with sophisticated molecular cell biology and imaging techniques and in vivo models. In Aim 1, we will develop an integrated experimental and computational model of collective cell movement in confined geometries modeling primary tumor invasion, and dissect the mechanisms by which cell-cell contact is released during mechanically-induced transitions to single cell movement, focusing on the role of E-cadherin cleavage and possible EMT induction. In Aim 2, we will delineate the relative contributions of actomyosin contractility, small GTPases and osmotic engine model to locomotion in rigid versus compliant confined microenvironments. In Aim 3, we will validate our in vitro understanding of the dissemination and locomotion of cancer cells in more complex microenvironments characteristic of in vivo breast tumors using an organotypic 3D culture system and genetically engineered mouse models. Elucidation of the underlying mechanisms of collective cancer cell invasion will offer insights into our understanding of how cancer cells spread through the body, and it could shift the currently prevailing single cell paradigm in cancer to incorporate concepts of mechanical signaling, cell-cell adhesion, and cell-cell cooperation.