Peter Friedl

The glycocalyx consists of glycoproteins, glycolipids and extracellular polysaccharides at the cell surface which mediate viscoelastic and electrostatic barrier function. In molecular interactions, the glycocalyx is thought to segregate locally to facilitate receptor-ligand binding, yet high-resolution maps of glycocalyx domains in cell-cell and cell-matrix interactions are lacking. We here apply TMTH-sulfoximine (THS)-based biorthogonal chemistry in live-cell culture and demonstrate enhanced glycocalyx detection, compared to established dibenzocyclooctyne-based labeling. Using superresolution microscopy in cancer cells, we identify micron-scale diminished glycocalyx in cell-cell contacts and depletion in protrusions at the leading and trailing edges and membrane blebs when cells invade 3D fibrillar matrix. At contacts to collagen fibrils, focal integrin clusters segregate ~350 nm outward from the glycocalyx level, forming adhesion sites of low glycocalyx content. Thus, we identify micro- and nanodomains with altered glycocalyx density using THS-based bioorthogonal labeling of live cells, implicating local glycocalyx downregulation in functional cell-cell and cell-matrix interactions.

Porous collagen hydrogels are widely used to model dynamic cell‐extracellular matrix (ECM) interactions relevant to inflammation, wound healing, and cancer invasion. To improve the physiological relevance of such assays, it is essential to incorporate architectural ECM characteristics identified in vivo that may affect the mechanical and molecular mechanisms of cell migration, including ECM geometry, alignment, and dimensionality. We present detailed, step‐by‐step protocols for generating three collagen‐hydrogel‐based migration assays that integrate structural guidance cues, either as cleft‐like deformable gaps or tunnel‐like tracks, including track generation by multiphoton (MP) laser ablation. For this application, practical guidance on laser setup and integration in commonly used MP microscopes is provided. We include example applications to compare the migratory behavior of HT1080 fibrosarcoma cells, applied both as single‐cell suspensions and as pre‐formed spheroids, in these spatially controlled models. The data indicate that migration efficiency increases with the presence of guidance cues, highlighting the importance of such cues for modeling invasive cell behavior in 3D. These protocols provide a standardized yet adaptable framework for researchers studying ECM‐guided cell migration and evaluating therapeutic strategies that target cell motility. © 2026 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1 : Under‐collagen assay Basic Protocol 2 : 3D interface assay Basic Protocol 3 : 3D tissue track assay Support Protocol 1 : Imaging of guidance models by confocal microscopy Support Protocol 2 : Excitation beam adjustment Support Protocol 3 : Generation of stacks of long tracks by three common microscope types

Plasticity of cell migration is a hallmark of cell movement during morphogenesis, tissue repair, and cancer metastasis. Interconversions of migration modes are tissue context–dependent and range from (1) collective migration of cohesive cells, migrating as epithelial sheets and strands; (2) multicellular networks of individualized cells moving while maintaining short-lived interactions; and (3) fully individualized cells moving by mesenchymal or amoeboid migration. Modes of cell migration, which are controlled by cell–cell adhesion, cell density, and active forces, can also be represented by physics-derived parameters, including temperature, applied stress, and volume fraction in classical passive jamming phase diagrams. Cell-packing density, cell–cell adhesion strength, and intrinsic migratory capacity have been defined as the key parameters driving jamming transitions in 2D sheet models, where extracellular matrix (ECM) is typically not considered. Here, we review how plasticity of cell migration programs intersects with jamming/unjamming principles and specifically focus on the impact of ECM architectures. In three-dimensional (3D) tissues, additional spatial parameters determine cell density and cell–cell interactions, including the degree of confinement forcing cells together versus the availability of free space. Integrating mechanisms of jamming/unjamming with actin-based active movement of cells in a 3D environment, similar to the motion of active nematic droplets in a passive nematic matrix, will enable building realistic models to predict cell behaviors in physiological and pathological contexts, including cancer metastasis.

Cell migration in mechanically confined environments is a crucial step of metastatic cancer progression. Nonetheless, the molecular components and processes mediating such behaviour are still not fully understood. Here we demonstrate that a pool of the scaffolding protein anillin and its cofactor Ect2, which are both predominantly nuclear proteins and critical mediators of cytokinesis, is present in the cytoplasm of multiple interphase cell types that promote confined cell migration. Confined migration in biomimetic microfluidic models triggers the actomyosin-binding-dependent recruitment of anillin to the plasma membrane at the poles of migrating cells in a manner that scales with microenvironmental stiffness and confinement. The guanine nucleotide exchange activity of Ect2 is required for its RhoA-GTPase-mediated activation of myosin II at the cell poles, enhancing invasion, bleb-based migration and extravasation. Confinement-induced nuclear envelope rupture further amplifies this process due to the release of further anillin and Ect2 into the cytoplasm. Overall, these results show how Ect2 and anillin cooperate to mediate RhoA/ROCK/myosin II-dependent mechanoadaptation and invasive cancer progression.

In breast cancer (BC), radial alignment of collagen fibers at the tumor-matrix interface facilitates collective invasion of cancer cells into the surrounding stromal matrix, a critical step toward metastasis. Collagen remodeling is driven by proteases and cellular forces, mediated by matrix mechanical plasticity, or irreversible matrix deformation in response to force. However, the specific mechanisms causing collagen radial alignment remain unclear. Here, we study collective invasion of BC tumor spheroids in collagen-rich matrices. Increasing plasticity to BC-relevant ranges facilitates invasion, with increasing stiffness potentiating a transition from single cell to collective invasion. At enhanced plasticity, cells radially align collagen at the tumor-matrix interface prior to invasion. Surprisingly, cells migrate tangentially to the tumor-matrix interface in a swirling-like motion, perpendicular to the direction of alignment. Mechanistically, swirling generates local shear stresses, leading to distally propagating contractile radial stresses due to negative normal stress, an underappreciated property of collagen-rich matrices. These contractile stresses align collagen fibers radially, facilitating collective invasion. The basement membrane (BM), which separates epithelia from stroma in healthy tissues, acts as a mechanical insulator by preventing swirling cells from aligning collagen. Thus, after breaching the BM, swirling of BC cells at the tumor-stroma interface radially aligns collagen to facilitate invasion.

Collective migration of cancer cells is often interpreted using concepts derived from the physics of active matter, but the experimental evidence is mostly restricted to observations made in vitro. Here, we study collective invasion of metastatic cancer cells injected into the mouse deep dermis using intravital multiphoton microscopy combined with a skin window technique and three-dimensional quantitative image analysis. We observe a multicellular but low-cohesive migration mode characterized by rotational patterns which self-organize into antiparallel persistent tracks with orientational nematic order. We analyze the deformations induced by the cells in the extracellular matrix and find broadly distributed strain bands with a prevalence of compression. A model of active nematic hydrodynamics is able to describe several statistical features of the experimentally observed flow, suggesting that collective cancer cell invasion can be interpreted as a nematic active fluid in the turbulent regime. Our results help elucidate the migration patterns of cancer cells in vivo and provide quantitative guidance for the development of realistic in vitro and in silico models for collective cell migration.

Peter Friedl (left) and Bettina Weigelin (right)Peter Friedl has uncovered intricate dynamics in immune cell interactions that have had immense impact on

The transition from collective to single-cell invasion in metastatic tumors has been regarded as the consequence of oncogenic drivers in concert with extracellular triggers received from the tumor microenvironment. In this issue, Yoon and colleagues (https://doi.org/10.1083/jcb.202308080) have identified an epigenetic program by which collective niches release laminin-332 and thereby cause the detachment and invasion of fully individualized tumor cells.

Cells migrating in confinement experience mechanical challenges whose consequences on cell migration machinery remain only partially understood. Here, we demonstrate that a pool of the cytokinesis regulatory protein anillin is retained during interphase in the cytoplasm of different cell types. Confinement induces recruitment of cytoplasmic anillin to plasma membrane at the poles of migrating cells, which is further enhanced upon nuclear envelope (NE) rupture(s). Rupture events also enable the cytoplasmic egress of predominantly nuclear RhoGEF Ect2. Anillin and Ect2 redistributions scale with microenvironmental stiffness and confinement, and are observed in confined cells in vitro and in invading tumor cells in vivo. Anillin, which binds actomyosin at the cell poles, and Ect2, which activates RhoA, cooperate additively to promote myosin II contractility, and promote efficient invasion and extravasation. Overall, our work provides a mechanistic understanding of how cytokinesis regulators mediate RhoA/ROCK/myosin II-dependent mechanoadaptation during confined migration and invasive cancer progression.