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，是癌症的一个标志。 癌细胞经常以粘附性细胞群的形式侵袭，这一过程称为集体侵袭。上一首 研究主要集中在单个细胞或半集体(多细胞流)细胞的侵袭。单人 转移的细胞模型对细胞作为个体进行结构性迁移的肿瘤有直接的影响 细胞，如白血病和淋巴瘤，或在细胞通过上皮到细胞从原发肿瘤分离后 间充质转化(EMT)。然而，EMT长期以来在病理学家中一直备受争议，就像乳腺一样 转移部位的肿瘤通常表现为上皮特征。虽然可以观察到类似EMT的基因签名 在特定的小鼠模型和乳腺癌亚型中，大多数乳腺肿瘤表现不明显 EMT的分子特征。活体显微镜研究表明，肿瘤细胞优先迁移 共同沿着由体内各种解剖结构定义的预先存在的通道。然而，它是 目前尚不清楚微环境的物理属性，如限制和顺应性， 调控集体细胞入侵的分子机制。耐人寻味的初步数据显示癌症 细胞作为一个集体单元在宽(≥50微米)轨道上迁移。然而，随着监禁的增加，癌症 细胞自发扩散，首先以2-5个细胞簇的形式传播，最终以非常窄的轨道(≤10微米)传播 单细胞。我们假设，物理微环境诱导了一系列信号级联事件， 将经典的集体入侵转变为单细胞入侵。为了检验这一假设，我们将使用一个 结合新的生物工程工具和复杂的数学建模的多学科方法 分子细胞生物学和成像技术以及活体模型。在目标1中，我们将开发一个集成的 受限几何模型中集体细胞运动的实验和计算模型 肿瘤侵袭，并剖析在机械诱导过程中细胞-细胞接触被释放的机制 过渡到单细胞运动，重点是E-钙粘蛋白裂解的作用和可能的EMT诱导。在……里面 目的2，我们将描述肌动球蛋白收缩、小GTP酶和渗透压的相对贡献 发动机模型在刚性与顺应性受限微环境中的运动。在目标3中，我们将验证 我们对癌细胞在体外的扩散和运动的了解更复杂 有机3D培养系统体内乳腺肿瘤的微环境特征 转基因小鼠模型。集体癌细胞潜在机制的阐明 侵袭将为我们理解癌细胞如何在体内传播提供洞察力，而且它可能 改变目前在癌症中流行的单细胞模式，将机械信号传递的概念纳入其中， 细胞间的黏附，细胞间的协作。

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.