Yan-Jun Liu

Metastasis, responsible for > 90% of cancer-related mortality, represents the most lethal yet least mechanistically understood phase of cancer progression. A critical bottleneck is tumor cell migration through physically confined environments, including dense extracellular matrix, narrow capillaries and endothelial gaps. Although tumor cells reprogram their metabolism to facilitate cancer progression, it remains unclear how specific metabolic adaptations enable them to overcome the unique physical challenges posed by these confined spaces, thereby promoting distant metastasis. We conducted a CRISPR screen targeting 1685 metabolic enzymes and identified dihydrolipoamide dehydrogenase (DLD), a mitochondrial enzyme involved in energy metabolism, as essential for confined migration of tumor cells. Depletion or pharmacological inhibition of DLD suppressed CRC metastasis by impairing tumor cell migration through capillaries and endothelial gaps. Upon mechanical compression, heterogeneous nuclear ribonucleoprotein A0 (hnRNPA0) binds to the adenylate uridylate-rich element (ARE) in the 3′UTR of DLD, enhancing its mRNA stability and upregulating DLD expression in tumor cells during confined migration. Elevated DLD expression enhances tricarboxylic acid (TCA) cycle metabolism, increasing malate levels. Malate interacts with tubulin alpha-1B chain (TUBA1B) to promote microtubule assembly, facilitating confined migration and metastasis. Knock-in of an ARE-deleted DLD mutant (DLD ΔARE) or disruption of the malate–TUBA1B interaction significantly suppressed tumor metastasis. In CRC patients, DLD expression was upregulated in tumor cells within capillaries of primary tumors and correlated with metastatic recurrence. Our findings reveal that compressive forces drive metastatic dissemination by epigenetically reprogramming mitochondrial metabolism, which in turn fuels cytoskeletal remodeling.

Cells in vivo experience mechanically diverse microenvironments in which physical confinement is a pervasive but poorly understood regulator of their behavior and fate. Whether and how mechanical confinement governs immune cell differentiation remains unknown. Here, we reveal that a mechanical cue — long-term confinement is sufficient to drive monocyte-to-macrophage differentiation through a mechanoepigenetic pathway. In vivo, differentiating monocytes exhibited flattened nuclei in the liver capsule, indicative of confinement by surrounding stromal and parenchymal structures. Using a custom cell confiner to recapitulate this confined niche, we found that confinement induces macrophage-like protrusive architectures, enhances motility, and upregulates macrophage-associated genes in RAW264.7 and THP-1 monocyte-lineage cells. Notably, extending this paradigm to primary murine bone-marrow, human umbilical-cord, and tissue-derived hepatic-associated monocytes yielded similar outcomes, thus enhancing phagocytic capacity, directly demonstrating that mechanical confinement can program monocytes into macrophages. Mechanistically, we found that confinement activates KDM6B, leading to H3K27me3 demethylation, which derepresses macrophage-specific transcriptional programs. Pharmacological inhibition of KDM6B with GSK-J4 restored H3K27me3 and blocked macrophage differentiation both in vitro and in vivo. These findings define a KDM6B–H3K27me3 axis that links nuclear mechanics to transcriptional reprogramming, positioning mechanical confinement as a “super-enhancer–like” cue for engineer macrophage function in therapeutic and bioengineering contexts.

Nonviral intracellular delivery based on pulsed-electric-field-induced electroporation is one of the most effective and widely used platforms in basic biological and biomedical research. However, the conventional bulk electroporation technique has exhibited limited performance in improving delivery efficiency with a single type of pulse, especially for in vivo small interfering RNA (siRNA) delivery. Pulse modulation has been confirmed effective in facilitating intracellular delivery. Nonetheless, pore evolution and regulation during and after electric exposure plays an essential role in the effective intracellular delivery of molecules with variable sizes. Here, we propose a progressive electroporation (PEP) strategy on the basis of multiple-pulse combination, which decouples the perforation process and delivery process compared to conventional bulk electroporation, efficiently improving delivery efficiency with regulation of the perforated pores. We demonstrated an important correlation between delivery efficiency enhancement and delayed pore resealing by quantitative investigations. The performance of this disruption-and-field-enhancement method also showed delivery advantages over conventional chemical systems. Moreover, we validated the improvement for siRNA knockdown efficacy in vivo. Overall, PEP helps provide a unique insight into improving intracellular delivery, by regulating pore dynamics rather than just inducing perforation. This strategic advancement of PEP may pave the way for the development of advanced wearable delivery systems with reduced energy consumption.

Cells navigate within diverse curved microenvironments derived from extracellular matrix (ECM) and neighboring cells in vivo. While current studies primarily focus on cell migration on curved surfaces, cellular adaptive responses to confinement-coupled geometric curvature remain largely unexplored. Herein, we design a confined curvature-based microfluidic chip (CCM-Chip) that mimics the physiologically relevant physical cues encountered during cell migration and investigate how cells dynamically answer to local geometric features. In the CCM-Chip, cells exhibit shape bending, nuclear deformation, and cytoskeletal remodeling that correlate with local geometric curvature. We then engineer a microgrooved uniaxial stretching microdevice to manipulate cell shape and find that curvature-induced cell shape results in nuclear envelope stretching, thus initiating downstream nuclear responses. Significantly, the stretched nuclear envelope effectively triggers the recruitment of cPLA2 to the nucleus, with nesprin and SUN1 serving as critical mediators in the process of nuclear mechanotransduction. The cPLA2 activation promotes stress fiber polarization at the cell front and enhances cellular contractility, facilitating curvature-induced cell migration. This work provides a versatile biomimetic microdevice for cell migration studies and highlights the key role of nuclear deformation-induced cPLA2 signaling in adaptive cell migration, advancing the development of therapeutic strategies against cancer metastasis.

Deep-learning-based structured illumination microscopy (SIM) has demonstrated substantial potential in long-term super-resolution imaging of biostructures, enabling the study of subcellular dynamics and interactions in live cells. However, the acquisition of ground-truth (GT) data for training poses inherent challenges, limiting its universal applicability. Current approaches without using GT training data compromise reconstruction fidelity and resolution, and the lack of physical priors in end-to-end networks further limits these qualities. Here we developed self-supervised reconstruction (SSR)-SIM by combining statistical analysis of reconstruction artifacts with structured light modulation priors to eliminate the need for GT and improve reconstruction precision. We validated SSR-SIM on common biological datasets and demonstrated that SSR-SIM enabled long-term recording of dynamic events, including cytoskeletal remodeling in cell adhesion, mitochondrial cristae remodeling, interactions between viral glycoprotein and endoplasmic reticulum, endocytic recycling of transferrin receptors, vaccinia-virus-induced actin comet remodeling, and mitochondrial intercellular transfer through tunneling nanotubes.

Genes regulating the finger-like cellular protrusions—filopodia have long been implicated in cancer metastasis. However, depleting the flat lamellipodia but retaining filopodia drastically hampers cell migration on spread surface, obscuring the role of filopodia in cell motility. It has been noticed recently that cells under confinement may employ distinct migratory machineries. However, the regulating factors have mainly been focused on cell blebbing, nuclear deformation and cell rear contractility, without much emphasis on cell protrusions and even less on filopodia. Here, by micropore-based screening, we identified espin as an active regulator for confined migration and that its overexpression was associated with metastasis. In comparison to fascin, espin showed stronger actin bundling in vitro and induced shorter and thicker filopodia in cells. Combining the imaging-compatible microchannels and DNA-based tension probes, we uncovered that espin overexpression induced excessive filopodia at the leading edge and along the sides, exerting force for confined migration. Our results demonstrate an important role for filopodia and the regulating protein—espin in confined cell migration and shed new light on cytoskeletal mechanisms underlying metastasis.

生物体通过感知环境并做出适应性反应来维持其生命活动，细胞在此过程中展现出感知与响应微环境信号的能力。除生物化学信号外，生物力学信号作为微环境的重要组成部分，近年来受到广泛关注，对细胞功能及生物体稳态至关重要。本文总结了微环境中的力学信号及其体外模拟重构方法，文章详细讨论了生物力学感受器的分类，包括酶介导型、转录因子响应型、离子通道型以及其他类型，并探讨了它们在感知力学刺激和信号转导中的作用。特别强调了细胞核在力学信号感受和传递中的重要作用，以及新型研究工具和技术在模拟体内力学环境中的应用前景。最后，文章展望了生物力学感受器研究的发展趋势，指出了深入理解生物力学感知机制对于疾病治疗和组织工程的重要意义。

Flagellar-driven locomotion plays a critical role in the bacterial attachment and colonization of surfaces, contributing to the risks of contamination and infection. Extensive efforts to uncover the underlying principles governing bacterial motility near surfaces have relied on idealized assumptions about surrounding artificial surfaces. However, in the context of living systems, the role of cells from tissues and organs becomes increasingly critical, particularly in bacterial swimming and adhesion, yet it remains poorly understood. Here, we propose using biological surfaces composed of vascular endothelial cells to experimentally investigate bacterial motion and interaction behaviors. Our results reveal that bacterial trapping observed on inorganic surfaces is counteractively manifested with reduced radii of circular motion on cellular surfaces. Additionally, two distinct modes of bacterial adhesion were identified: tight and loose adhesion. Interestingly, the presence of living cells enhances bacterial surface enrichment, and imposed flow intensifies this accumulation via a bias-swimming effect. These results surprisingly indicate that physical effects remain the dominant factor regulating bacterial motility and accumulation at the single-cell-layer level in vitro, bridging the gap between simplified hydrodynamic mechanisms and complex biological surfaces with relevance to biofilm formation and bacterial contamination.

Flagellar-driven locomotion plays a critical role in bacterial attachment and colonization of surfaces, contributing to the risks of contamination and infection. Tremendous attempts to uncover the underlying principles governing bacterial motility near surfaces have relied on idealized assumptions of surrounding inorganic boundaries. However, in the context of living systems, the role of cells from tissues and organs becomes increasingly critical, particularly in bacterial swimming and adhesion, yet it remains poorly understood. Here, we propose using biological surfaces composed of vascular endothelial cells to experimentally investigate bacterial motion and interaction behaviors. Our results reveal that bacterial trapping observed on inorganic surfaces is counteractively manifested with reduced radii of circular motion on cellular surfaces, while with two distinct modes of bacterial adhesion: tight adhesion and loose adhesion. Interestingly, the presence of living cells enhances bacterial surface enrichment, and imposed flow intensifies this accumulation via bias-swimming effect. These results surprisingly indicate that physical effects remain the dominant factor regulating bacterial motility and accumulation at the single-cell layer level in vitro, bridging the gap between simplified hydrodynamic mechanisms and complex biological surfaces, with relevance to biofilm formation and bacterial contamination.

While tumor organoids have revolutionized cancer research by recapitulating the cellular architecture and behaviors of real tumors in vitro, their lack of functional vasculature hinders their attainment of full physiological capabilities. Current efforts to vascularize organoids are struggling to achieve well‐defined vascular networks, mimicking the intricate hierarchy observed in vivo, which restricts the physiological relevance particularly for studying tumor progression and response to therapies targeting the tumor vasculature. An innovative vascularized patient‐derived tumor organoids (PDTOs)‐on‐a‐chip with hierarchical, tumor‐specific microvasculature is presented, providing a versatile platform to explore tumor‐vascular dynamics and antivascular drug efficacy. It is found that highly metastatic tumor cells induced vessel angiogenesis and simultaneously migrated toward blood vessels via the Notch pathway. The evident association between the angiogenic and migratory capacities of PDTOs and their clinical metastatic outcomes underscores the potential of the innovative platform for evaluating tumor metastasis, thus offering valuable insights for clinical decision‐making. Ultimately, the system represents a promising avenue for advancing the understanding of tumor metastasis and developing personalized treatment strategies based on patient‐specific tumor characteristics.