Blebbing Driven or Actin Protrusive-Force Driven Cancer Cell Migration

三维细胞外基质中的细胞迁移是组织组装和再生、免疫细胞运输和癌症等疾病的先决条件。此外，转移过程依赖于单个癌细胞的迁移。间质迁移是一个由多个步骤组成的循环过程，如肌动蛋白聚合依赖的前沿假足突起，整合素介导的细胞外基质粘附，接触依赖的细胞外基质通过细胞表面蛋白酶引起的裂解降解，肌动球蛋白促进了细胞体的收缩，增加了纵向张力和细胞后部的收缩，随后是细胞体的移位。这只描述了转移细胞的一种特定的迁移模式：突出模式，而还有其他模式，特别是起泡模式。在特定的环境条件下，特定的癌细胞倾向于哪种侵袭模式正在讨论中。然而，癌症转移的能力取决于细胞迁移到结缔组织、粘附以及可能通过内皮迁移的能力。是什么决定了入侵的模式，以及不同模式之间的出现或切换是如何被调节的，这仍然是难以捉摸的。侵袭方式的选择对肿瘤细胞基底膜或内皮屏障电位的调节及侵袭速度有重要影响。迁移细胞如何成功地克服在密集基质中发现的各种障碍，在很大程度上取决于它的机械特性以及它如何产生突出力。因此，力和材料特性决定了癌细胞有利的侵入性迁移模式。我们已经确定，与收缩性较差的癌细胞相比，具有某些机械特性（如收缩力传递和产生）的癌细胞更有效地侵入三维细胞外基质。我们的项目将阐明癌细胞调节其入侵模式的主要机制，以及细胞外基质的力学和结构等微环境特性在其中所起的作用。为了研究这一点，我们将通过确定细胞骨架和质膜刚度的影响，剖析侵袭模式和环境约束（如网状或孔隙大小、整个细胞的刚度、质膜和细胞外基质）之间的串扰，以及细胞粘附机制的蛋白质组学以及细胞外蛋白质组成。细胞粘附性和细胞收缩性对侵袭性细胞运动的影响，以及这些因素在多大程度上有利于突出或以气泡为基础的运动。最后，我们的数据将扩展我们对癌细胞及其微环境的机械特性对上皮源性癌症的侵袭和转移行为的各自贡献的理解。

Cell migration in 3D extracellular matrices is a prerequisite for tissue assembly and regeneration, immune cell trafficking, and diseases such as cancer. Moreover, the process of metastasis depends on the migration of single cancer cells. The interstitial migration is a cyclic process consisting of multiple steps such as the actin polymerization-dependent pseudopod protrusion at the leading edge, the integrin-mediated adhesion to the extracellular matrix, the contact-dependent extracellular matrix degradation through the cleavage evoked by cell surface proteases, the actomyosin-facilitated contraction of the cell body increasing longitudinal tension and the retraction of the cell rear followed by the translocation of the cell body. This describes only one particular migration mode of metastatic cells: the protrusive mode, whereas there are still other modes, in particular the blebbing mode. Which invasion mode is favored by certain cancer cells and under specific environmental conditions is under discussion. However, the capability of cancers to metastasize depends on the cells ability to migrate into connective tissue, adhere, and possibly transmigrate through the endothelium. It is still elusive what determines the mode of invasion and how the appearance or the switch between the different modes is regulated. The choice of the invasion mode is supposed to have an important impact on the regulation of the basement membrane or endothelial barrier-crossing potential of cancer cells and their invasion speed. How successful a migrating cell overcomes different obstacles found in dense matrices depends highly on its mechanical properties and how it generates its protrusive forces. Thus forces and material properties determine the favorable invasive migration mode for cancer cells. We have established that cancer cells with certain mechanical properties such as contractile force transmission and generation invade more efficiently into 3D extracellular matrices compared to less contractile cancer cells. Our project will elucidate major mechanisms by which cancer cells regulate their invasion mode and what role the microenvironmental properties such as mechanics and structure of the extracellular matrix play. To investigate this, we will dissect the crosstalk between invasion modes and environmental constraints such as mesh or pore size, stiffness of the entire cell, the plasma membrane and the extracellular matrix, and the proteomics of the cellular adhesion machinery as well as extracellular protein composition by determining the influence of cytoskeletal and plasma membrane stiffness, cell adhesion and cell contractility on invasive cell motility and to what extent this factors favor protrusive or blebbing-based motion. Finally, our data will expand our understanding of the respective contribution of mechanical properties of cancer cells and their microenvironment to the invasive and metastatic behavior of epithelial-derived cancers.