Collective cell migration in morphogenesis, regeneration and cancer

Spatiotemporal dissection of collective cell migration and tissue morphogenesis during development by optogenetics

Collective cell migration and tissue morphogenesis play a variety of important roles in the development of many species. Tissue morphogenesis often generates mechanical forces that alter cell shapes and arrangements, resembling collective cell migration-like behaviors. Genetic methods have been widely used to study collective cell migration and its like behavior, advancing our understanding of these processes during development. However, a growing body of research shows that collective cell migration during development is not a simple behavior but is often combined with other cellular and tissue processes. In addition, different surrounding environments can also influence migrating cells, further complicating collective cell migration during development. Due to the complexity of developmental processes and tissues, traditional genetic approaches often encounter challenges and limitations. Thus, some methods with spatiotemporal control become urgent in dissecting collective cell migration and tissue morphogenesis during development. Optogenetics is a method that combines optics and genetics, providing a perfect strategy for spatiotemporally controlling corresponding protein activity in subcellular, cellular or tissue levels. In this review, we introduce the basic mechanisms underlying different optogenetic tools. Then, we demonstrate how optogenetic methods have been applied in vivo to dissect collective cell migration and tissue morphogenesis during development. Additionally, we describe some promising optogenetic approaches for advancing this field. Together, this review will guide and facilitate future studies of collective cell migration in vivo and tissue morphogenesis by optogenetics.

Active Nematics Reinforce the Ratchet Flow in Dense Environments Without Jamming

The past decade witnessed a surge in discoveries where biological systems, such as bacteria or living cells, inherently portray active polar or nematic behavior: they prefer to align with each other and form local order during migration. Although the underlying mechanisms remain unclear, utilizing their physical properties to achieve controllable cell-layer transport will be of fundamental importance. In this study, the ratchet effect is harnessed to control the collective motion of neural progenitor cells (NPCs) in vitro. NPCs travel back-and-forth and do not specify head or tail, and therefore regarded as nematics alike liquid crystals. Ratchet and splay-shaped confinements are crafted to modulate collective cell dynamics in dense environments, while jamming is not explicitly spotted. The adaptation of an agent-based simulation further revealed how the ratchet's asymmetry and active forces from nematic order synergistically reinforce the directional cell flow. These findings provide insights into topotaxis in cell populations when restricted to crowded 2D ratchets and the mechanisms that regulate collective behavior of the cells.

Gradients in cell density and shape transitions drive collective cell migration into confining environments

Epithelial cell collectives migrate through tissue interfaces and crevices to orchestrate development processes, tumor invasion, and wound healing. Naturally, the traversal of cell collective through confining environments involves crowding due to narrowing spaces, which seems tenuous given the conventional inverse relationship between cell density and migration. However, the physical transitions required to overcome such epithelial densification for migration across confinements remain unclear. Here, in a system of contiguous microchannels of varying confinements, we show that epithelial (MCF10A) monolayers accumulate higher cell density and undergo fluid-like shape transitions before entering narrower channels. However, overexpression of breast cancer oncogene ErbB2 did not require such accumulation of cell density to migrate across matrix confinement. While wild-type MCF10A cells migrated faster in narrow channels, this confinement sensitivity was reduced after +ErbB2 mutation or with constitutively active RhoA. This physical interpretation of collective cell migration as density and shape transitions in granular matter could advance our understanding of complex living systems.

Stretch-induced endogenous electric fields drive directed collective cell migration in vivo

Directed collective cell migration is essential for morphogenesis, and chemical, electrical, mechanical and topological features have been shown to guide cell migration in vitro. Here we provide in vivo evidence showing that endogenous electric fields drive the directed collective cell migration of an embryonic stem cell population-the cephalic neural crest of Xenopus laevis. We demonstrate that the voltage-sensitive phosphatase 1 is a key component of the molecular mechanism, enabling neural crest cells to specifically transduce electric fields into a directional cue in vivo. Finally, we propose that endogenous electric fields are mechanically established by the convergent extension movements of the ectoderm, which generate a membrane tension gradient that opens stretch-activated ion channels. Overall, these findings establish a role for electrotaxis in tissue morphogenesis, highlighting the functions of endogenous bioelectrical stimuli in non-neural contexts.

Vertex model with internal dissipation enables sustained flows

Complex tissue flows in epithelia are driven by intra- and inter-cellular processes that generate, maintain, and coordinate mechanical forces. There has been growing evidence that cell shape anisotropy, manifested as nematic order, plays an important role in this process. Here we extend an active nematic vertex model by replacing substrate friction with internal viscous dissipation, dominant in epithelia not supported by a substrate or the extracellular matrix, which are found in many early-stage embryos. When coupled to cell shape anisotropy, the internal viscous dissipation allows for long-range velocity correlations and thus enables the spontaneous emergence of flows with a large degree of spatiotemporal organisation. We demonstrate sustained flow in epithelial sheets confined to a channel, providing a link between the cell-level vertex model of tissue dynamics and continuum active nematics, whose behaviour in a channel is theoretically understood and experimentally realisable. Our findings also show a simple mechanism that could account for collective cell migration correlated over distances large compared to the cell size, as observed during morphogenesis.

Angiomotin cleavage promotes leader formation and collective cell migration

Collective cell migration (CCM) is involved in multiple biological processes, including embryonic morphogenesis, angiogenesis, and cancer invasion. However, the molecular mechanisms underlying CCM, especially leader cell formation, are poorly understood. Here, we show that a signaling pathway regulating angiomotin (AMOT) cleavage plays a role in CCM, using mammalian epithelial cells and mouse models. In a confluent epithelial monolayer, full-length AMOT localizes at cell-cell junctions and limits cell motility. After cleavage, the C-terminal fragment of AMOT (AMOT-CT) translocates to the cell-matrix interface to promote the maturation of focal adhesions (FAs), generate traction force, and induce leader cell formation. Meanwhile, decreased full-length AMOT at cell-cell junctions leads to tissue fluidization and coherent migration of cell collectives. Hence, the cleavage of AMOT serves as a molecular switch to generate polarized contraction, promoting leader cell formation and CCM.

Tao and Rap2l ensure proper Misshapen activation and levels during Drosophila border cell migration

Collective cell migration is fundamental in development, wound healing, and metastasis. During Drosophila oogenesis, border cells (BCs) migrate collectively inside the egg chamber, controlled by the Ste20-like kinase Misshapen (Msn). Msn coordinates the restriction of protrusion formation and contractile forces within the cluster. Here, we demonstrate that Tao acts as an upstream activator of Msn in BCs. Depleting Tao significantly impedes BC migration, producing a phenotype similar to Msn loss of function. Furthermore, we show that the localization of Msn relies on its citron homology (CNH) domain, which interacts with the small GTPase Rap2l. Rap2l promotes the trafficking of Msn to the endolysosomal pathway. Depleting Rap2l elevates Msn levels by reducing its trafficking into late endosomes and increases overall contractility. These data suggest that Tao promotes Msn activation, while global Msn protein levels are controlled via Rap2l and the endolysosomal degradation pathway. Thus, two mechanisms ensure appropriate Msn levels and activation in BCs.

The structure-dynamics feedback mechanism governs the glassy dynamics in epithelial monolayers

The glass-like slow dynamics in confluent epithelial monolayers is crucial for wound healing, embryogenesis, cancer progression, etc. Experiments have indicated several unusual properties in these systems. Unlike ordinary glasses, the glassiness in cellular systems strongly correlates with their static properties and is sub-Arrhenius. These results imply that the slow dynamics in epithelial monolayers is either not glassy or the underlying mechanism is different from ordinary glasses. Combining the analytical mode-coupling theory (MCT), vertex model simulations, and cellular experiments, we show that the slow dynamics is glassy, though the mechanism differs from ordinary glasses. The structure-dynamics feedback mechanism of MCT, and not the barrier-crossing mechanism, dominates the glassy dynamics, where the relaxation time diverges as a power law with a universal exponent 3/2 and naturally explains the sub-Arrhenius relaxation. Our results suggest the possibility of describing various complex biological processes like cell division and apoptosis via the static properties of the systems, such as average cell shape or shape variability.

Fast yet force-effective mode of supracellular collective cell migration due to extracellular force transmission

Cell collectives, like other motile entities, generate and use forces to move forward. Here, we ask whether environmental configurations alter this proportional force-speed relationship, since aligned extracellular matrix fibers are known to cause directed migration. We show that aligned fibers serve as active conduits for spatial propagation of cellular mechanotransduction through matrix exoskeleton, leading to efficient directed collective cell migration. Epithelial (MCF10A) cell clusters adhered to soft substrates with aligned collagen fibers (AF) migrate faster with much lesser traction forces, compared to random fibers (RF). Fiber alignment causes higher motility waves and transmission of normal stresses deeper into cell monolayer while minimizing shear stresses and increased cell-division based fluidization. By contrast, fiber randomization induces cellular jamming due to breakage in motility waves, disrupted transmission of normal stresses, and heightened shear driven flow. Using a novel motor-clutch model, we explain that such 'force-effective' fast migration phenotype occurs due to rapid stabilization of contractile forces at the migrating front, enabled by higher frictional forces arising from simultaneous compressive loading of parallel fiber-substrate connections. We also model 'haptotaxis' to show that increasing ligand connectivity (but not continuity) increases migration efficiency. According to our model, increased rate of front stabilization via higher resistance to substrate deformation is sufficient to capture 'durotaxis'. Thus, our findings reveal a new paradigm wherein the rate of leading-edge stabilization determines the efficiency of supracellular collective cell migration.

Topography-Mediated Induction of Epithelial Mesenchymal Transition via Alumina Textiles for Potential Wound Healing Applications

Substrate topography is vital in determining cell growth and fate of cellular behavior. Although current in vitro studies of the underlying cellular signaling pathways mostly rely on their induction by specific growth factors or chemicals, the influence of substrate topography on specific changes in cells has been explored less often. This study explores the impact of substrate topography, specifically the tricot knit microfibrous structure of alumina textiles, on cell behavior, focusing on fibroblasts and keratinocytes for potential wound healing applications. The textiles, studied for the first time as in vitro substrates, demonstrated support for keratinocyte adhesion, leading to alterations in cell morphology and the expression of E-cadherin and fibronectin. These topography-induced changes resembled the epithelial-to-mesenchymal transition (EMT), crucial for wound healing, and were specific to keratinocytes and absent in identically treated fibroblasts. Biochemically induced EMT in keratinocytes cultured on flat alumina substrates mirrored the changes seen with alumina textiles alone, suggesting the tricot knit microfibrous topography could serve as an in vitro model system to induce EMT-like mechanisms. These results enhance our understanding of how substrate topography influences EMT-related processes in wound healing, paving the way for further evaluation of microfibrous alumina textiles as innovative wound dressings.

Confinement-sensitive volume regulation dynamics via high-speed nuclear morphological measurements

Diverse tissues in vivo present varying degrees of confinement, constriction, and compression to migrating cells in both homeostasis and disease. The nucleus in particular is subjected to external forces by the physical environment during confined migration. While many systems have been developed to induce nuclear deformation and analyze resultant functional changes, much remains unclear about dynamic volume regulation in confinement due to limitations in time resolution and difficulty imaging in PDMS-based microfluidic chips. Standard volumetric measurement relies on confocal microscopy, which suffers from high phototoxicity, slow speed, limited throughput, and artifacts in fast-moving cells. To address this, we developed a form of double fluorescence exclusion microscopy, designed to function at the interface of microchannel-based PDMS sidewalls, that can track cellular and nuclear volume dynamics during confined migration. By verifying the vertical symmetry of nuclei in confinement, we obtained computational estimates of nuclear surface area. We then tracked nuclear volume and surface area under physiological confinement at a time resolution exceeding 30 frames per minute. We find that during self-induced entrance into confinement, the cell rapidly expands its surface area until a threshold is reached, followed by a rapid decrease in nuclear volume. We next used osmotic shock as a tool to alter nuclear volume in confinement, and found that the nuclear response to hypo-osmotic shock in confinement does not follow classical scaling laws, suggesting that the limited expansion potential of the nuclear envelope might be a constraining factor in nuclear volume regulation in confining environments in vivo.

Transitions between cooperative and crowding-dominated collective motion in non-jammed MDCK monolayers

Transitions between solid-like and fluid-like states in living tissues have been found in steps of embryonic development and in stages of disease progression. Our current understanding of these transitions has been guided by experimental and theoretical investigations focused on how motion becomes arrested with increased mechanical coupling between cells, typically as a function of packing density or cell cohesiveness. However, cells actively respond to externally applied forces by contracting after a time delay, so it is possible that at some packing densities or levels of cell cohesiveness, mechanical coupling stimulates cell motion instead of suppressing it. Here we report our findings that at low densities and within multiple ranges of cell cohesiveness, cell migration speeds increase with these measures of mechanical coupling. Our observations run counter to our intuition that cell motion will be suppressed by increasingly packing or sticking cells together and may provide new insight into biological processes involving motion in dense cell populations.

Subchronic Exposure to Low-Level Lanthanum, Cerium, and Yttrium Mixtures Altered Cell Cycle and Increased Oxidative Stress Pathways in Human LO-2 Hepatocytes but Did Not Cause Malignant Transformation

Human exposures to rare earth elements are increasing with expanded use in aerospace, precision instruments, and new energy batteries, materials, and fertilizers. Individually these elements have low toxicity, although few investigations have examined the health effects of longer-term mixture exposures. We used the LO-2 cell line to examine the effects of graded exposures to lanthanum, cerium, and yttrium (LCY) mixtures at 1-, 100-, and 1000-fold their human background levels (0.31 μg/L La, 0.25 μg/L Ce, and 0.12 μg/L Y) on cell cycle, oxidative stress, and nuclear factor erythroid-2-related factor (NRF2) pathway biomarkers, assessing responses every 10 passages up to 100 passages. Cell migration, concanavalin A, malignant transformation, and tumorigenesis in nude mice were also examined. Mixed LCY exposures activated oxidative stress and the NRF2 pathway by the 30th passage and increased the proportion of cells in the S phase and cell cycle-specific biomarkers by the 40th passage. LCY exposures did not cause malignant transformation of hepatocytes or induced tumorigenesis in nude mice but enhanced cell proliferation, migration, and agglutination. Importantly, LCY mixtures with longer-term exposure activated the NRF2 pathway and altered the hepatocyte cell cycle at doses far below those used in previous toxicological studies. The consequences of LCY mixtures for public health merit further study.

Competing elastic and viscous gradients determine directional cell migration

Cell migration regulates central life processes including embryonic development, tissue regeneration, and tumor invasion. To establish the direction of migration, cells follow exogenous cues. Durotaxis, the directed cell migration towards elastic stiffness gradients, is the classical example of mechanical taxis. However, whether gradients of the relaxation properties in the extracellular matrix may also induce tactic responses (viscotaxis) is not well understood. Moreover, whether and how durotaxis and viscotaxis interact with each other has never been investigated. Here, we integrate clutch models for cell adhesions with an active gel theory of cell migration to reveal the mechanisms that govern viscotaxis. We show that viscotaxis is enabled by an asymmetric expression of cell adhesions that further polarize the intracellular motility forces to establish the cell front, similar to durotaxis. More importantly, when both relaxation and elastic gradients coexist, durotaxis appears more efficient in controlling directed cell migration, which we confirm with experimental results. However, the presence of opposing relaxation gradients to an elastic one can arrest or shift the migration direction. Our model rationalizes for the first time the mechanisms that govern viscotaxis and its competition with durotaxis through a mathematical model.

Effects of cell shape and nucleus shape on epithelial-mesenchymal transition revealed using chimeric micropatterns

Epithelial-mesenchymal transition (EMT) is a key phenotypic switch in cancer metastasis, leading to fatal consequences for patients. Under geometric constraints, the morphology of cancer cells changes in both cellular and subcellular levels, whose effects on EMT are, however, not fully understood. Herein, we designed and fabricated chimeric micropatterns of polystyrene (PS) with adhesion contrast to reveal the impacts of cell shapes and nuclear shapes on EMT in a decoupled way. Cell elongation was modulated via microwell aspect ratios (ARs), and nuclear deformation was generated through a micropillar array in the microwell. Human non-small cell lung cancer cells (A549) were cultured on the quasi-three dimensional micropatterned surfaces, and transforming growth factor-β1 (TGF-β1) was added to induce EMT. We found that chimeric micropatterns upregulated EMT with an increase of cellular AR and nuclear indentation under given TGF-β1. The subsequent assessment of the contractility and oriented assembly of microfilaments elucidated the key role of mechanotransduction in cell elongation and EMT, as proved by myosin inhibition, while it was obstructed by micropillars in the chimeric micropattern. Hence, the micropillar array possessed a nonmonotonic influence, enhancing the EMT of cells with AR of 1, but hindering the EMT with an impact more significant on microwells with large ARs due to the impeded cytoskeleton assembly. This fundamental research has illustrated the complex of cellular and subcellular geometries on cell behaviors including phenotype transition in cancer metastasis.

Unjamming Transition as a Paradigm for Biomechanical Control of Cancer Metastasis

Tumor metastasis is a complex phenomenon that poses significant challenges to current cancer therapeutics. While the biochemical signaling involved in promoting motile phenotypes is well understood, the role of biomechanical interactions has recently begun to be incorporated into models of tumor cell migration. Specifically, we propose the unjamming transition, adapted from physical paradigms describing the behavior of granular materials, to better discern the transition toward an invasive phenotype. In this review, we introduce the jamming transition broadly and narrow our discussion to the different modes of 3D tumor cell migration that arise. Then we discuss the mechanical interactions between tumor cells and their neighbors, along with the interactions between tumor cells and the surrounding extracellular matrix. We center our discussion on the interactions that induce a motile state or unjamming transition in these contexts. By considering the interplay between biochemical and biomechanical signaling in tumor cell migration, we can advance our understanding of biomechanical control in cancer metastasis.

CYRI controls epidermal wound closure and cohesion of invasive border cell cluster in Drosophila

Cell motility is crucial for many biological processes including morphogenesis, wound healing, and cancer invasion. The WAVE regulatory complex (WRC) is a central Arp2/3 regulator driving cell motility downstream of activation by Rac GTPase. CYFIP-related Rac1 interactor (CYRI) proteins are thought to compete with WRC for interaction with Rac1 in a feedback loop regulating lamellipodia dynamics. However, the physiological role of CYRI proteins in vivo in healthy tissues is unclear. Here, we used Drosophila as a model system to study CYRI function at the cellular and organismal levels. We found that CYRI is not only a potent WRC regulator in single macrophages that controls lamellipodial spreading but also identified CYRI as a molecular brake on the Rac-WRC-Arp2/3 pathway to slow down epidermal wound healing. In addition, we found that CYRI limits invasive border cell migration by controlling cluster cohesion and migration. Thus, our data highlight CYRI as an important regulator of cellular and epithelial tissue dynamics conserved across species.

Modelling the effect of cell motility on mixing and invasion in epithelial monolayers

Collective cell invasion underlies several biological processes such as wound healing, embryonic development, and cancerous invasion. Here, we investigate the impact of cell motility on invasion in epithelial monolayers and its coupling to cellular mechanical properties, such as cell-cell adhesion and cortex contractility. We develop a two-dimensional computational model for cells with active motility based on the cellular Potts model, which predicts that the cellular invasion speed is mainly determined by active cell motility and is independent of the biological and mechanical properties of the cells. We also find that, in general, motile cells out-compete and invade non-motile cells, however, this can be reversed by differential cell proliferation. Stable coexistence of motile and static cell types is also possible for certain parameter regimes.

Isotoosendanin inhibits triple-negative breast cancer metastasis by reducing mitochondrial fission and lamellipodia formation regulated by the Smad2/3-GOT2-MYH9 signaling axis

Triple-negative breast cancer (TNBC) is incurable and prone to widespread metastasis. Therefore, identification of key targets for TNBC progression is urgently needed. Our previous study revealed that isotoosendanin (ITSN) reduced TNBC metastasis by targeting TGFβR1. ITSN is currently used as an effective chemical probe to further discover the key molecules involved in TNBC metastasis downstream of TGFβR1. The results showed that GOT2 was the gene downstream of Smad2/3 and that ITSN decreased GOT2 expression by abrogating the activation of the TGF-β-Smad2/3 signaling pathway through directly binding to TGFβR1. GOT2 was highly expressed in TNBC, and its knockdown decreased TNBC metastasis. However, GOT2 overexpression reversed the inhibitory effect of ITSN on TNBC metastasis both in vitro and in vivo. GOT2 interacted with MYH9 and hindered its binding to the E3 ubiquitin ligase STUB1, thereby reducing MYH9 ubiquitination and degradation. Moreover, GOT2 also enhanced the translocation of MYH9 to mitochondria and thus induced DRP1 phosphorylation, thereby promoting mitochondrial fission and lamellipodia formation in TNBC cells. ITSN-mediated inhibition of mitochondrial fission and lamellipodia formation was associated with reduced GOT2 expression. In conclusion, ITSN prevented MYH9-regulated mitochondrial fission and lamellipodia formation in TNBC cells by enhancing MYH9 protein degradation through a reduction in GOT2 expression, thus contributing to its inhibition of TNBC metastasis.

Intercellular junction-driven stromal cell stacking in a confined 3D microcavity

Understanding the detailed mechanisms driving fibroblast migration within native tissue settings during pathophysiological events presents a critical research challenge. In this study, we elucidate how stromal cells migrate and contribute to the development of three-dimensional (3D) cellular aggregates within confined microcavities. Integrin α5β1 and β-catenin (β-cat) are central in guiding this collective migration and achieving optimal filling of the microcavity. When β-cat is suppressed, cells tend to migrate more sporadically, leading to less efficient cellular organization. Furthermore, we also detail the pivotal roles of Cx43 and N-cadherin (N-cad) in orchestrating collective migration and in shaping efficient cellular stacking. Suppressing gap junctions, especially Cx43, significantly impacts the extracellular matrix expression, integrin α5 and β1, and other elements in the 3D construct, emphasizing the importance of physicochemical cell-cell interactions. The distribution patterns of N-cad and focal adhesion kinase (FAK) further corroborate the essential roles in forming cell-cell junctions and FAK in establishing the foundational layer that underpins the cell stacking within the microcavity. Interestingly, neither Rho-associated protein kinase (ROCK) nor RhoA significantly alter the cell migration pattern toward microcavity. These findings provide fresh perspectives on fibroblast activities in 3D space, enriching our understanding and offering implications for advancements in wound healing and tissue engineering.

Interferon Induced Upregulation of Tripartite Motif 34 (TRIM34) Leads Apoptotic Cell Death in Lung Adenocarcinoma

Despite breakthroughs in our understanding of lung cancer risk, development, immunologic control, and therapy choices, it remains one of the leading causes of cancer mortality. This study aimed to investigate the role of TRIM34 upon treatment of Interferon Gamma (IFN-γ) in Non-Small Cell Lung Cancer (NSCLC). NCI-H23 cells were exposed to IFN-γ in a dose- and time-dependent manner to understand TRIM34 expression and its role as a co-regulator of treatment. The regulatory role of TRIM34 on IFN-γ exposure was studied by qRT-PCR, Western blot analysis, immunocytochemistry, apoptosis assay and scratch assay. On exposure to IFN-γ, TRIM34 expression at transcript and protein level was significantly upregulated. With its upregulation, NCI-H23 underwent apoptosis and its rate of proliferation was impeded. Our results suggest that induction of TRIM34 by IFN-γ treatment may lead to an anti-tumor inflammatory response, resulting in NSCLC regression via apoptosis.

In vitro regulation of collective cell migration: Understanding the role of physical and chemical microenvironments

Collective cell migration is the primary mode of cellular movement during embryonic morphogenesis, tissue repair and regeneration, and cancer invasion. Distinct from single-cell migration, collective cell migration involves complex intercellular signaling cascades and force transmission. Consequently, cell collectives exhibit intricate and diverse migration patterns under the influence of the microenvironment in vivo. Investigating the patterns and mechanisms of collective cell migration within complex environmental factors in vitro is essential for elucidating collective cell migration in vivo. This review elucidates the influence of physical and chemical factors in vitro microenvironment on the migration patterns and efficiency of cell collectives, thereby enhancing our comprehension of the phenomenon. Furthermore, we concisely present the effects of characteristic properties of common biomaterials on collective cell migration during tissue repair and regeneration, as well as the features and applications of tumor models of different dimensions (2D substrate or 3D substrate) in vitro. Finally, we highlight the challenges facing the research of collective cell migration behaviors in vitro microenvironment and propose that modulating collective cell migration may represent a potential strategy to promote tissue repair and regeneration and to control tumor invasion and metastasis.

Leader cells promote immunosuppression to drive ovarian cancer progression in vivo

Over 75% of patients with ovarian cancer present with late-stage disease, often accompanied by extensive metastasis. The metastatic cascade is driven by a sub-population of transcriptionally plastic cells known as "leader cells" (LCs), which play a critical role in collective invasion yet remain poorly understood. LCs are marked by the expression of keratin-14 (KRT14), which determines their migratory and invasive capacity in ovarian cancer. This study demonstrates that KRT14+ LCs promote tumor progression through immunosuppression and immune privilege in vivo. In the ID8 syngeneic epithelial ovarian cancer mouse model, tumor-specific loss of KRT14+ LCs impairs tumor progression and metastatic spread without affecting cellular proliferation. Immune profiling shows reduced immunosuppressive regulatory T cells (Tregs) and M2 macrophages and improved CD8+ T cell/Treg ratios in LC knockout (LCKO) mice. Conversely, forced LC overexpression accelerates metastasis and increases the secretion of immunosuppressive chemokines, such as CCL22 and CCL5, highlighting the role of KRT14+ LCs in immune suppression and metastatic progression.

Spontaneous flows and quantum analogies in heterogeneous active nematic films

Incorporating the inherent heterogeneity of living systems into models of active nematics is essential to provide a more realistic description of biological processes such as bacterial growth, cell dynamics and tissue development. Spontaneous flow of a confined active nematic is a fundamental feature of these systems, in which the role of heterogeneity has not yet been considered. We therefore determine the form of spontaneous flow transition for an active nematic film with heterogeneous activity, identifying a correspondence between the unstable director modes and solutions to Schrödinger's equation. We consider both activity gradients and steps between regions of distinct activity, finding that such variations can change the signature properties of the flow. The threshold activity required for the transition can be raised or lowered, the fluid flux can be reduced or reversed and interfaces in activity induce shear flows. In a biological context fluid flux influences the spread of nutrients while shear flows affect the behaviour of rheotactic microswimmers and can cause the deformation of biofilms. All the effects we identify are found to be strongly dependent on not simply the types of activity present in the film but also on how they are distributed.

An allosteric inhibitor of RhoGAP class-IX myosins suppresses the metastatic features of cancer cells

Aberrant Ras homologous (Rho) GTPase signalling is a major driver of cancer metastasis, and GTPase-activating proteins (GAPs), the negative regulators of RhoGTPases, are considered promising targets for suppressing metastasis, yet drug discovery efforts have remained elusive. Here, we report the identification and characterization of adhibin, a synthetic allosteric inhibitor of RhoGAP class-IX myosins that abrogates ATPase and motor function, suppressing RhoGTPase-mediated modes of cancer cell metastasis. In human and murine adenocarcinoma and melanoma cell models, including three-dimensional spheroid cultures, we reveal anti-migratory and anti-adhesive properties of adhibin that originate from local disturbances in RhoA/ROCK-regulated signalling, affecting actin-dynamics and actomyosin-based cell-contractility. Adhibin blocks membrane protrusion formation, disturbs remodelling of cell-matrix adhesions, affects contractile ring formation, and disrupts epithelial junction stability; processes severely impairing single/collective cell migration and cytokinesis. Combined with the non-toxic, non-pathological signatures of adhibin validated in organoids, mouse and Drosophila models, this mechanism of action provides the basis for developing anti-metastatic cancer therapies.

Enhancing cell motility via non-contact capacitively coupled electrostatic field

Cellular motility is essential for making and maintaining multicellular organisms throughout their lifespan. Migrating cells can move either individually or collectively by a crawling movement that links the cytoskeletal activity to the adhesion surface. In vitro stimulation by electric fields can be achieved by direct, capacitive or inductive coupled setups. We tested the effects of electrical stimulation provided by capacitive coupling on glioma cells, using a capacitive-coupled system powered by a potential difference of 35 V between two electrodes placed outside the culture dish. Numerical dosimetry identified two different fields: (i) in the order of 103 V/m at the level of the dielectric substrates, with almost uniform distribution; (ii) in the order of 10-1 V/m at the level of the culture medium, with spatial and material-dependent distribution. The scratch assay and the tracking of single-cell movement showed a boosted motility when crawling occurs on polystyrene surfaces, demonstrating the feasibility of this peculiar exposure system to generate forces capable of influencing cell behavior.

Intra-tumoral YAP and TAZ heterogeneity drives collective NSCLC invasion that is targeted by SUMOylation inhibitor TAK-981

Non-small cell lung cancer (NSCLC) collective invasion is supported by cooperativity of proliferative (follower) and invasive (leader) cells. H1299-isolated follower cells exhibit higher Yes-associated protein (YAP) expression, while leader cells were found to express elevated transcriptional coactivator with PDZ-binding motif (TAZ/WWTR1) expression. Suppressing TAZ (not YAP) in leader cells reduced invasion. TAZ-regulated leader cell invasion is associated with activation of the EGFR-PI3K-AKT axis. NSCLC patient samples also demonstrated heterogeneity in YAP and TAZ expression. YAP and TAZ regulate proliferation of follower and leader cells. Our results highlight the need to inhibit both YAP and TAZ to effectively target their regulation of collective invasion. We identify that the SUMOylation inhibitor TAK-981 reduces YAP and TAZ expression, decreasing tumor burden and metastasis in a murine NSCLC model. Our study reveals an intra-tumoral division of labor, driven by differential YAP and TAZ expression, which can be effectively targeted with TAK-981 for NSCLC therapy.

Microfluidic Platform for Generating and Releasing Patient-Derived Cancer Organoids with Diverse Shapes: Insight into Shape-Dependent Tumor Growth

Multicellular spheroids and patient-derived organoids find many applications in fundamental research, drug discovery, and regenerative medicine. Advances in the understanding and recapitulation of organ functionality and disease development require the generation of complex organoid models, including organoids with diverse morphologies. Microfluidics-based cell culture platforms enable time-efficient confined organoid generation. However, the ability to form organoids with different shapes with a subsequent transfer from microfluidic devices to unconstrained environments for studies of morphology-dependent organoid growth is yet to be demonstrated. Here, a microfluidic platform is introduced that enables high-fidelity formation and addressable release of breast cancer organoids with diverse shapes. Using this platform, the impact of organoid morphology on their growth in unconstrained biomimetic hydrogel is explored. It is shown that proliferative cancer cells tend to localize in high positive curvature organoid regions, causing their faster growth, while the overall growth pattern of organoids with diverse shapes tends to reduce interfacial tension at the organoid-hydrogel interface. In addition to the formation of organoids with diverse morphologies, this platform can be integrated into multi-tissue micro-physiological systems.

Practical immunomodulatory landscape of glioblastoma multiforme (GBM) therapy

Glioblastoma multiforme (GBM) is the most common harmful high-grade brain tumor with high mortality and low survival rate. Importantly, besides routine diagnostic and therapeutic methods, modern and useful practical techniques are urgently needed for this serious malignancy. Correspondingly, the translational medicine focusing on genetic and epigenetic profiles of glioblastoma, as well as the immune framework and brain microenvironment, based on these challenging findings, indicates that key clinical interventions include immunotherapy, such as immunoassay, oncolytic viral therapy, and chimeric antigen receptor T (CAR T) cell therapy, which are of great importance in both diagnosis and therapy. Relatively, vaccine therapy reflects the untapped confidence to enhance GBM outcomes. Ongoing advances in immunotherapy, which utilizes different methods to regenerate or modify the resistant body for cancer therapy, have revealed serious results with many different problems and difficulties for patients. Safe checkpoint inhibitors, adoptive cellular treatment, cellular and peptide antibodies, and other innovations give researchers an endless cluster of instruments to plan profoundly in personalized medicine and the potential for combination techniques. In this way, antibodies that block immune checkpoints, particularly those that target the program death 1 (PD-1)/PD-1 (PD-L1) ligand pathway, have improved prognosis in a wide range of diseases. However, its use in combination with chemotherapy, radiation therapy, or monotherapy is ineffective in treating GBM. The purpose of this review is to provide an up-to-date overview of the translational elements concentrating on the immunotherapeutic field of GBM alongside describing the molecular mechanism involved in GBM and related signaling pathways, presenting both historical perspectives and future directions underlying basic and clinical practice.

Long range juxtacrine signalling through cadherin for collective cell orientation

Many life phenomena, such as development, morphogenesis, tissue remodelling, and wound healing, are often driven by orderly and directional migration of collective cells. However, when cells are randomly oriented or localized disorder exists in orderly oriented collective cells, cell migration cannot occur in an orderly manner although various motion modes such as global rotation and local swirling and/or various motion patterns such as radial pattern and chiral pattern often occur. Therefore, it is important to control cell orientation to ensure the orderly migration of collective cells. Here, we show that it is not force transmission, but juxtacrine signalling through cadherin that plays a critical role in the orientation of collective cells. Surprisingly, juxtacrine signalling for cell orientation reached cells on a plastic dish that were not directly subjected to mechanical stimulation, up to 7 mm away from the actuator. The present study suggests that even weak mechanical stimulation is transmitted in a long range without force transmission through juxtacrine signalling. The long range juxtacrine signalling might play an important role in various life phenomena. STATEMENT OF SIGNIFICANCE: Juxtacrine signalling is direct cell-cell contact-dependent signalling, which plays a crucial role in cell behaviors such as mechanosensing, mechanotransduction and collective cell behaviors, however, there is not enough understanding about juxtacrine signalling. The present study has demonstrated that juxtacrine signalling for collective cell orientation is transmitted over a long range through cadherin. To the best of our knowledge, this is the first report of long range juxtacrine signalling. This finding may lead to the elucidation of various life phenomena such as development, morphogenesis, tissue remodelling, and wound healing.

Variations in cell plasticity and proliferation underlie distinct modes of regeneration along the antero-posterior axis in the annelid Platynereis

The capacity to regenerate lost tissues varies significantly among animals. Some phyla, such as the annelids, display substantial regenerating abilities, although little is known about the cellular mechanisms underlying the process. To precisely determine the origin, plasticity and fate of the cells participating in blastema formation and posterior end regeneration after amputation in the annelid Platynereis dumerilii, we developed specific tools to track different cell populations. Using these tools, we find that regeneration is partly promoted by a population of proliferative gut cells whose regenerative potential varies as a function of their position along the antero-posterior axis of the worm. Gut progenitors from anterior differentiated tissues are lineage restricted, whereas gut progenitors from the less differentiated and more proliferative posterior tissues are much more plastic. However, they are unable to regenerate the stem cells responsible for the growth of the worms. Those stem cells are of local origin, deriving from the cells present in the segment abutting the amputation plane, as are most of the blastema cells. Our results favour a hybrid and flexible cellular model for posterior regeneration in Platynereis relying on different degrees of cell plasticity.

Plexin/Semaphorin Antagonism Orchestrates Collective Cell Migration, Gap Closure and Organ sculpting by Contact-Mesenchymalization

Cell behavior emerges from the intracellular distribution of properties like protrusion, contractility and adhesion. Thus, characteristic emergent rules of collective migration can arise from cell-cell contacts locally tweaking architecture - orchestrating self-regulation during development, wound healing, and cancer progression. The new Drosophila testis-nascent-myotube-system allows dissection of contact-dependent migration in vivo at high resolution. Here, we describe a process driving gap-closure during migration: Contact-mesenchymalization via the axon guidance factor Plexin A. This is crucial for testis myotubes to migrate as a continuous sheet, allowing normal sculpting-morphogenesis. Cells must stay filopodial and dynamically ECM-tethered near cell-cell contacts to spread while collectively moving. Our data suggest Semaphorin 1B acts as a Plexin A antagonist, fine-tuning activation. Our data reveal a contact-dependent mechanism to maintain sheet-integrity during migration, driving organ-morphogenesis using a highly conserved pathway. This is relevant for understanding mesenchymal organ-sculpting and gap-closure in migratory contexts like angiogenesis.

Preparing a Phytosome for Promoting Delivery Efficiency and Biological Activities of Methyl Jasmonate-Treated Dendropanax morbifera Adventitious Root Extract (DMARE)

(1) Background: Methyl jasmonate-treated D. morbifera adventitious root extract (MeJA-DMARE), enriched with phenolics, has enhanced bioactivities. However, phenolics possess low stability and bioavailability. Substantial evidence indicates that plant extract-phospholipid complex assemblies, known as phytosomes, represent an innovative drug delivery system. (2) Methods: The phytosome complex was created by combining MeJA-DMARE with Soy-L-α-phosphatidylcholine (PC) using three different ratios through two distinct methods (co-solvency method: A1, A2, and A3; thin-layer film method: B1, B2, and B3). (3) Results: Initial evaluation based on UV-Vis, entrapment efficiency (EE%), and loading content (LC%) indicated that B2 exhibited the highest EE% (79.98 ± 1.45) and LC% (69.17 ± 0.14). The phytosome displayed a spherical morphology with a particle size of 210 nm, a notably low polydispersity index of 0.16, and a superior zeta potential value at -25.19 mV. The synthesized phytosome exhibited superior anti-inflammatory activities by inhibiting NO and ROS production (reduced to 8.9% and 55.1% at 250 μg/mL) in RAW cells and adjusting the expression of related inflammatory cytokines; they also slowed lung tumor cell migration (only 2.3% of A549 cells migrated after treatment with phytosomes at 250 μg/mL), promoting ROS generation in A549 cell lines (123.7% compared to control) and stimulating apoptosis of lung cancer-related genes. (4) Conclusions: In conclusion, the MeJA-DMARE phytosome offers stable, economically efficient, and environmentally friendly nanoparticles with superior inflammation and lung tumor inhibition properties. Thus, the MeJA-DMARE phytosome holds promise as an applicable and favorable creation for drug delivery and lung cancer treatment.

Miniature Modular Reconfigurable Underwater Robot Based on Synthetic Jet

Modular reconfigurable robots exhibit prominent advantages in the reconnaissance and exploration tasks within unstructured environments for their characteristics of high adaptability and high robustness. However, due to the limitations in locomotion mechanism and integration requirements, the modular design of miniature robots in the aquatic environment encounters significant challenges. Here, a modular strategy based on the synthetic jet principle is proposed, and a modular reconfigurable robot system is developed. Specialized bottom and side jet actuators are designed with vibration motors as excitation sources, and a motion module is developed incorporating the jet actuators to realize three-dimensional agile motion. Its linear, rotational, and ascending motion speeds reach 70.7 mm s-1, 3.3 rad s-1, and 28.7 mm s-1, respectively. The module integrates the power supply, communication, and control system with a small size of 48 mm × 38 mm × 38 mm, which ensures a wireless controllable motion. Then, various configurations of the multi-module robot system are established with corresponding motion schemes, and the experiments with replaceable intermediate modules are further conducted to verify the transportation and image-capturing functions. This work demonstrates the effectiveness of synthetic jet propulsion for aquatic modular reconfigurable robot systems, and it exhibits profound potential in future underwater applications.

Divergent iron regulatory states contribute to heterogeneity in breast cancer aggressiveness

Contact with dense collagen I (Col1) can induce collective invasion of triple negative breast cancer (TNBC) cells and transcriptional signatures linked to poor patient prognosis. However, this response is heterogeneous and not well understood. Using phenotype-guided sequencing analysis of invasive vs. noninvasive subpopulations, we show that these two phenotypes represent opposite sides of the iron response protein 1 (IRP1)-mediated response to cytoplasmic labile iron pool (cLIP) levels. Invasive cells upregulate iron uptake and utilization machinery characteristic of a low cLIP response, which includes contractility regulating genes that drive migration. Non-invasive cells upregulate iron sequestration machinery characteristic of a high cLIP response, which is accompanied by upregulation of actin sequestration genes. These divergent IRP1 responses result from Col1-induced transient expression of heme oxygenase I (HO-1), which cleaves heme and releases iron. These findings lend insight into the emerging theory that heme and iron fluxes regulate TNBC aggressiveness.

Circulating Tumor Cells: Origin, Role, Current Applications, and Future Perspectives for Personalized Medicine

Circulating tumor cells (CTCs) currently represent a revolutionary tool offering unique insights for the evaluation of cancer progression, metastasis, and response to therapies. Indeed, CTCs, upon detachment from primary tumors, enter the bloodstream and acquire a great potential for their use for personalized cancer management. In this review, we describe the current understanding of and advances in the clinical employment of CTCs. Although considered rare and fleeting, CTCs are now recognized as key players favoring the development of cancer metastasis and disease recurrence, particularly in malignant melanoma, lung, breast, and colorectal cancer patients. To date, the advancements in technology and the development of several successful approaches, also including immunomagnetic enrichment allow for a reliable and reproducible detection and characterization of CTCs. Those innovative methodologies improved the isolation, quantification, and characterization of CTCs from the blood of cancer patients, providing extremely useful evidence and new insights into the nature of the tumor, its epithelial/mesenchymal profile, and its potential resistance to therapy. In fact, in addition to their prognostic and predictive value, CTCs could serve as a valuable instrument for real-time monitoring of treatment response and disease recurrence, facilitating timely interventions and thus improving patient outcomes. However, despite their potential, several challenges hinder the widespread clinical utility of CTCs: (i) CTCs' rarity and heterogeneity pose technical limitations in isolation and characterization, as well as significant hurdles in their clinical implementation; (ii) it is mandatory to standardize CTC detection methods, optimize the sample processing techniques, and integrate them with existing diagnostic modalities; and (iii) the need for the development of new techniques, such as single-cell analysis platforms, to enhance the sensitivity and specificity of CTC detection, thereby facilitating their integration into routine clinical practice. In conclusion, CTCs represent a potential extraordinary tool in cancer diagnostics and therapeutics, offering unprecedented opportunities for personalized medicine and precision oncology. Moreover, their ability to provide real-time insights into tumor biology, treatment response, and disease progression underlines a great potential for their clinical application to improve patients' outcomes and advance our understanding of cancer biology.

Versatile system cores as a conceptual basis for generality in cell and developmental biology

The discovery of general principles underlying the complexity and diversity of cellular and developmental systems is a central and long-standing aim of biology. While new technologies collect data at an ever-accelerating rate, there is growing concern that conceptual progress is not keeping pace. We contend that this is due to a paucity of conceptual frameworks that support meaningful generalizations. This led us to develop the core and periphery (C&P) hypothesis, which posits that many biological systems can be decomposed into a highly versatile core with a large behavioral repertoire and a specific periphery that configures said core to perform one particular function. Versatile cores tend to be widely reused across biology, which confers generality to theories describing them. Here, we introduce this concept and describe examples at multiple scales, including Turing patterning, actomyosin dynamics, multi-cellular morphogenesis, and vertebrate gastrulation. We also sketch its evolutionary basis and discuss key implications and open questions. We propose that the C&P hypothesis could unlock new avenues of conceptual progress in mesoscale biology.

Regulation of intercellular viscosity by E-cadherin-dependent phosphorylation of EGFR in collective cell migration

Collective cell migration is crucial in various physiological processes, including wound healing, morphogenesis, and cancer metastasis. Adherens Junctions (AJs) play a pivotal role in regulating cell cohesion and migration dynamics during tissue remodeling. While the role and origin of the junctional mechanical tension at AJs have been extensively studied, the influence of the actin cortex structure and dynamics on junction plasticity remains incompletely understood. Moreover, the mechanisms underlying stress dissipation at junctions are not well elucidated. Here, we found that the ligand-independent phosphorylation of epithelial growth factor receptor (EGFR) downstream of de novo E-cadherin adhesion orchestrates a feedback loop, governing intercellular viscosity via the Rac pathway regulating actin dynamics. Our findings highlight how the E-cadherin-dependent EGFR activity controls the migration mode of collective cell movements independently of intercellular tension. This modulation of effective viscosity coordinates cellular movements within the expanding monolayer, inducing a transition from swirling to laminar flow patterns while maintaining a constant migration front speed. Additionally, we propose a vertex model with adjustable junctional viscosity, capable of replicating all observed cellular flow phenotypes experimentally.

CO2-Free On-Stage Incubator for Live Cell Imaging of Cholangiocarcinoma Cell Migration on Microfluidic Device

Long-term live cell imaging requires sophisticated and fully automated commercial-stage incubators equipped with specified inverted microscopes to regulate temperature, CO2 content, and humidity. In this study, we present a CO2-free on-stage incubator specifically designed for use across various cell culture platforms, enabling live cell imaging applications. A simple and transparent incubator was fabricated from acrylic sheets to be easily placed on the stages of most inverted microscopes. We successfully performed live-cell imaging of cholangiocarcinoma (CCA) cells and HeLa cell dynamics in both 2D and 3D microenvironments over three days. We also analyzed directed cell migration under high serum induction within a microfluidic device. Interesting phenomena such as "whole-colony migration", "novel type of collective cell migration" and "colony formation during cell and colony migration" are reported here for the first time, to the best of our knowledge. These phenomena may improve our understanding of the nature of cell migration and cancer metastasis.

Lost in Rotation: How TiO2 and ZnO Nanoparticles Disrupt Coordinated Epithelial Cell Rotation

Coordinated cell movement is a cardinal feature in tissue organization that highlights the importance of cells working together as a collective unit. Disruptions to this synchronization can have far-reaching pathological consequences, ranging from developmental disorders to tissue repair impairment. Herein, it is shown that metal oxide nanoparticles (NPs), even at low and non-toxic doses (1 and 10 µg mL-1), can perturb the coordinated epithelial cell rotation (CECR) in micropatterned human epithelial cell clusters via distinct nanoparticle-specific mechanisms. Zinc oxide (ZnO) NPs are found to induce significant levels of intracellular reactive oxygen species (ROS) to promote mitogenic activity. Generation of a new localized force field through changes in the cytoskeleton organization and an increase in cell density leads to the arrest of CECR. Conversely, epithelial cell clusters exposed to titanium dioxide (TiO2) NPs maintain their CECR directionality but display suppressed rotational speed in an autophagy-dependent manner. Thus, these findings reveal that nanoparticles can actively hijack the nano-adaptive responses of epithelial cells to disrupt the fundamental mechanics of cooperation and communication in a collective setting.

Innovating Cancer Treatment Through Cell Cycle, Telomerase, Angiogenesis, and Metastasis

Cancer remains a formidable challenge in the field of medicine, necessitating innovative therapeutic strategies to combat its relentless progression. The cell cycle, a tightly regulated process governing cell growth and division, plays a pivotal role in cancer development. Dysregulation of the cell cycle allows cancer cells to proliferate uncontrollably. Therapeutic interventions designed to disrupt the cell cycle offer promise in restraining tumor growth and progression. Telomerase, an enzyme responsible for maintaining telomere length, is often overactive in cancer cells, conferring them with immortality. Targeting telomerase presents an opportunity to limit the replicative potential of cancer cells and hinder tumor growth. Angiogenesis, the formation of new blood vessels, is essential for tumor growth and metastasis. Strategies aimed at inhibiting angiogenesis seek to deprive tumors of their vital blood supply, thereby impeding their progression. Metastasis, the spread of cancer cells from the primary tumor to distant sites, is a major challenge in cancer therapy. Research efforts are focused on understanding the underlying mechanisms of metastasis and developing interventions to disrupt this deadly process. This review provides a glimpse into the multifaceted approach to cancer therapy, addressing critical aspects of cancer biology-cell cycle regulation, telomerase activity, angiogenesis, and metastasis. Through ongoing research and innovative strategies, the field of oncology continues to advance, offering new hope for improved treatment outcomes and enhanced quality of life for cancer patients.

Loading of bacterial cellulose dressing with frutalin, a lectin from Artocarpus incisa L

Bacterial cellulose (BC), produced by bacterial fermentation, is a high-purity material. BC can be oxidized (BCOXI), providing aldehyde groups for covalent bonds with drugs. Frutalin (FTL) is a lectin capable of modulating cell proliferation and remodeling, which accelerates wound healing. This study aimed to develop an FTL-incorporated dressing based on BC, and to evaluate its physicochemical properties and biological activity in vitro. An experimental design was employed to maximize FTL loading yield onto the BC and BCOXI, where independent variables were FTL concentration, temperature and immobilization time. BCOXI-FTL 1 (44.96 % ± 1.34) had the highest incorporation yield (IY) at the experimental conditions: 6 h, 5 °C, 20 μg mL-1. The second highest yield was BCOXI-FTL 6 (23.28 % ± 1.43) using 24 h, 5 °C, 100 μg mL-1. Similarly, the same reaction parameters provided higher immobilization yields for native bacterial cellulose: BC-FTL 6 (16.91 % ± 1.05) and BC-FTL 1 (21.71 % ± 1.57). Purified FTL displayed no cytotoxicity to fibroblast cells (<50 μg mL-1 concentration) during 24 h. Furthermore, BCOXI-FTL and BC-FTL were non-cytotoxic during 24 h and stimulated fibroblast migration. BCOXI-FTL demonstrated neutrophil activation in vitro similar to FTL. These promising results indicate that the bacterial cellulose matrices containing FTL at low concentrations, could be used as an innovative biomaterial for developing wound dressings.

Mechanisms of metastatic colorectal cancer

Despite extensive research and improvements in understanding colorectal cancer (CRC), its metastatic form continues to pose a substantial challenge, primarily owing to limited therapeutic options and a poor prognosis. This Review addresses the emerging focus on metastatic CRC (mCRC), which has historically been under-studied compared with primary CRC despite its lethality. We delve into two crucial aspects: the molecular and cellular determinants facilitating CRC metastasis and the principles guiding the evolution of metastatic disease. Initially, we examine the genetic alterations integral to CRC metastasis, connecting them to clinically marked characteristics of advanced CRC. Subsequently, we scrutinize the role of cellular heterogeneity and plasticity in metastatic spread and therapy resistance. Finally, we explore how the tumour microenvironment influences metastatic disease, emphasizing the effect of stromal gene programmes and the immune context. The ongoing research in these fields holds immense importance, as its future implications are projected to revolutionize the treatment of patients with mCRC, hopefully offering a promising outlook for their survival.

Sensory nerves drive migration of dental pulp stem cells via the CGRP-Ramp1 axis in pulp repair

Dental pulp stem cells (DPSCs) are responsible for maintaining pulp structure and function after pulp injury. DPSCs migrate directionally to the injury site before differentiating into odontoblast-like cells, which is a prerequisite and a determinant in pulp repair. Increasing evidence suggests that sensory neuron-stem cell crosstalk is critical for maintaining normal physiological functions, and sensory nerves influence stem cells mainly by neuropeptides. However, the role of sensory nerves on DPSC behaviors after pulp injury is largely unexplored. Here, we find that sensory nerves released significant amounts of calcitonin gene-related peptide (CGRP) near the injury site, acting directly on DPSCs via receptor activity modifying protein 1 (RAMP1) to promote collective migration of DPSCs to the injury site, and ultimately promoting pulp repair. Specifically, sensory denervation leads to poor pulp repair and ectopic mineralization, in parallel with that DPSCs failed to be recruited to the injury site. Furthermore, in vitro evidence shows that sensory nerve-deficient microenvironment suppressed DPSC migration prominently among all related behaviors. Mechanistically, the CGRP-Ramp1 axis between sensory neurons and DPSCs was screened by single-cell RNA-seq analysis and immunohistochemical studies confirmed that the expression of CGRP rather than Ramp1 increases substantially near the damaged site. We further demonstrated that CGRP released by sensory nerves binds the receptor Ramp1 on DPSCs to facilitate cell collective migration by an indirect co-culture system using conditioned medium from trigeminal neurons, CGRP recombinant protein and antagonists BIBN4096. The treatment with exogenous CGRP promoted the recruitment of DPSCs, and ultimately enhanced the quality of pulp repair. Targeting the sensory nerve could therefore provide a new strategy for stem cell-based pulp repair and regeneration.

Cell-substrate distance fluctuations of confluent cells enable fast and coherent collective migration

Collective cell migration is an emergent phenomenon, with long-range cell-cell communication influenced by various factors, including transmission of forces, viscoelasticity of individual cells, substrate interactions, and mechanotransduction. We investigate how alterations in cell-substrate distance fluctuations, cell-substrate adhesion, and traction forces impact the average velocity and temporal-spatial correlation of confluent monolayers formed by either wild-type (WT) MDCKII cells or zonula occludens (ZO)-1/2-depleted MDCKII cells (double knockdown [dKD]) representing highly contractile cells. The data indicate that confluent dKD monolayers exhibit decreased average velocity compared to less contractile WT cells concomitant with increased substrate adhesion, reduced traction forces, a more compact shape, diminished cell-cell interactions, and reduced cell-substrate distance fluctuations. Depletion of basal actin and myosin further supports the notion that short-range cell-substrate interactions, particularly fluctuations driven by basal actomyosin, significantly influence the migration speed of the monolayer on a larger length scale.

Galvanotactic directionality of cell groups depends on group size

Motile cells migrate directionally in the electric field in a process known as galvanotaxis, important and under-investigated phenomenon in wound healing and development. We previously reported that individual fish keratocyte cells migrate to the cathode in electric fields, that inhibition of PI3 kinase reverses single cells to the anode, and that large cohesive groups of either unperturbed or PI3K-inhibited cells migrate to the cathode. Here we find that small uninhibited cell groups move to the cathode, while small groups of PI3K-inhibited cells move to the anode. Small groups move faster than large groups, and groups of unperturbed cells move faster than PI3K-inhibited cell groups of comparable sizes. Shapes and sizes of large groups change little when they start migrating, while size and shapes of small groups change significantly, lamellipodia disappear from the rear edges of these groups, and their shapes start to resemble giant single cells. Our results are consistent with the computational model, according to which cells inside and at the edge of the groups pool their propulsive forces to move but interpret directional signals differently. Namely, cells in the group interior are directed to the cathode independently of their chemical state. Meanwhile, the edge cells behave like individual cells: they are directed to the cathode/anode in uninhibited/PI3K-inhibited groups, respectively. As a result, all cells drive uninhibited groups to the cathode, while larger PI3K-inhibited groups are directed by cell majority in the group interior to the cathode, while majority of the edge cells in small groups win the tug-of-war driving these groups to the anode.

An RNAi screen for ribosome biogenesis genes required for Drosophila border cell collective migration

Ribosome biogenesis is critical for the proper production of proteins in cells and has emerged as a regulator of cell invasion and migration in development and in cancer. The Drosophila border cells form a collective that invades and migrates through the surrounding tissue during oogenesis. We previously found that a significant number of ribosome biogenesis genes are differentially expressed from early to late migration stages. Here, we performed a small-scale RNAi screen of a subset of these ribosome genes. Knockdown of seven genes disrupted border cell migration, thus revealing a role for ribosome biogenesis genes in regulating collective cell migration.

Motility driven glassy dynamics in confluent epithelial monolayers

As wounds heal, embryos develop, cancer spreads, or asthma progresses, the cellular monolayer undergoes a glass transition between solid-like jammed and fluid-like flowing states. During some of these processes, the cells undergo an epithelial-to-mesenchymal transition (EMT): they acquire in-plane polarity and become motile. Thus, how motility drives the glassy dynamics in epithelial systems is critical for the EMT process. However, no analytical framework that is indispensable for deeper insights exists. Here, we develop such a theory inspired by a well-known glass theory. One crucial result of this work is that the confluency affects the effective persistence time-scale of active force, described by its rotational diffusivity, Deffr. Deffr differs from the bare rotational diffusivity, Dr, of the motile force due to cell shape dynamics, which acts to rectify the force dynamics: Deffr is equal to Dr when Dr is small and saturates when Dr is large. We test the theoretical prediction of Deffr and how it affects the relaxation dynamics in our simulations of the active Vertex model. This novel effect of Deffr is crucial to understanding the new and previously published simulation data of active glassy dynamics in epithelial monolayers.

Differential transcriptional invasion signatures from patient derived organoid models define a functional prognostic tool for head and neck cancer

Clinical outcome for patients suffering from HPV-negative head and neck squamous cell carcinoma (HNSCC) remains poor. This is mostly due to highly invasive tumors that cause loco-regional relapses after initial therapeutic intervention and metastatic outgrowth. The molecular pathways governing the detrimental invasive growth modes in HNSCC remain however understudied. Here, we have established HNSCC patient derived organoid (PDO) models that recapitulate 3-dimensional invasion in vitro. Single cell mRNA sequencing was applied to study the differences between non-invasive and invasive conditions, and in a collective versus single cell invading PDO model. Differential expression analysis under invasive conditions in Collagen gels reveals an overall upregulation of a YAP-centered transcriptional program, irrespective of the invasion mode. However, we find that collectively invading HNSCC PDO cells show elevated levels of YAP transcription targets when compared to single cell invasion. Also, collectively invading cells are characterized by increased nuclear translocation of YAP within the invasive strands, which coincides with Collagen-I matrix alignment at the invasive front. Using gene set enrichment analysis, we identify immune cell-like migratory pathways in the single cell invading HNSCC PDO, while collective invasion is characterized by overt upregulation of adhesion and migratory pathways. Lastly, based on clinical head and neck cancer cohorts, we demonstrate that the identified collective invasion signature provides a candidate prognostic platform for survival in HNSCC. By uncoupling collective and single cell invasive programs, we have established invasion signatures that may guide new therapeutic options.