Integrin α5β1 facilitates cancer cell invasion through enhanced contractile forces

Softness or Stiffness What Contributes to Cancer and Cancer Metastasis?

Beyond the genomic and proteomic analysis of bulk and single cancer cells, a new focus of cancer research is emerging that is based on the mechanical analysis of cancer cells. Therefore, several biophysical techniques have been developed and adapted. The characterization of cancer cells, like human cancer cell lines, started with their mechanical characterization at mostly a single timepoint. A universal hypothesis has been proposed that cancer cells need to be softer to migrate and invade tissues and subsequently metastasize in targeted organs. Thus, the softness of cancer cells has been suggested to serve as a universal physical marker for the malignancy of cancer types. However, it has turned out that there exists the opposite phenomenon, namely that stiffer cancer cells are more migratory and invasive and therefore lead to more metastases. These contradictory results question the universality of the role of softness of cancer cells in the malignant progression of cancers. Another problem is that the various biophysical techniques used can affect the mechanical properties of cancer cells, making it even more difficult to compare the results of different studies. Apart from the instrumentation, the culture and measurement conditions of the cancer cells can influence the mechanical measurements. The review highlights the main advances of the mechanical characterization of cancer cells, discusses the strength and weaknesses of the approaches, and questions whether the passive mechanical characterization of cancer cells is still state-of-the art. Besides the cell models, conditions and biophysical setups, the role of the microenvironment on the mechanical characteristics of cancer cells is presented and debated. Finally, combinatorial approaches to determine the malignant potential of tumors, such as the involvement of the ECM, the cells in a homogeneous or heterogeneous association, or biological multi-omics analyses, together with the dynamic-mechanical analysis of cancer cells, are highlighted as new frontiers of research.

Effect of precursors on carbon dot functionalization and applications: a review

Carbon dots (CDs) are a type of carbon-based nanoparticle (NP) that have risen in popularity due to their unique tuneable physicochemical and optical properties. CDs have received a significant amount of attention in biological based applications due to their low cytotoxicity, stable photoluminescence, and small size. They have demonstrated the ability to retain certain properties from their carbon precursors, enabling NP design via precursor selection. Thus, direct functionalization of a CD can be achieved without the need for post synthesis modification. However, CDs derived from the same class of carbon precursor can also have profoundly variable applications. Indicating that, in conjunction with precursor properties, other functional attributes can be imposed on the CD during the synthesis process to enable cross-cutting applications from a single carbon precursor. Here, we will highlight various CD precursors and the resulting multifunctional CDs, as well as rational design of CDs for specific biological and materials science applications via precursor selection.

Blockade of ITGA2/3/5 Promotes Adipogenic Differentiation of Human Adipose-derived Mesenchymal Stem Cells

The integrin α (ITGA) subfamily genes play a fundamental role in various cancers. However, the potential mechanism and application values of ITGA genes in adipogenic differentiation of human adipose-derived stem cells (hADSCs) remain elusive. This study confirmed that ITGA2/3/5 mRNA expressions were repressed during adipogenesis. Blockade of ITGA2/3/5 enhanced adipogenic differentiation of hADSCs. Oil red O staining found that more lipid droplets were apparent in the ITGA2/3/5 inhibition group following 14 d adipogenic induction than in the control group. In addition, inhibition of ITGA2/3/5 promoted the expression of adipogenesis-related genes (PPAR-γ, C/EBPα, FABP4). Mechanistically, ITGA2/3/5 functioned by regulating the Rac1 signaling pathway, which reasonably explains ITGA2/3/5's role in adipogenic differentiation of hADSCs. Our studies suggest that blockades of ITGA2/3/5 promote the adipogenic differentiation of hADSCs.

Integrin-α5 expression and its role in non-small cell lung cancer progression

Integrins are transmembrane receptors that facilitate cell adhesion to the extracellular matrix and neighboring cells. Aberrant expression of integrins has been associated with tumor progression and metastasis in various cancer types. Integrin alpha-5 (ITGA5) is an integrin subtype that serves as a receptor for fibronectin, fibrinogen, and fibrillin-1. The purpose of this study was to elucidate how ITGA5 expression plays a role in human non-small cell lung cancer (NSCLC). Our clinical data, along with data retrieved from The Cancer Genome Database (TCGA), revealed that high ITGA5 expression in NSCLC patients was associated with a lower recurrence-free survival and overall survival. In our in vitro functional assays, ITGA5 overexpression in human NSCLC cell lines resulted in increased cell size, adhesion, and migration properties, while knockdown of ITGA5 restored the phenotypes. Correspondingly, knockdown and inhibition of ITGA5 in endogenously high-expressing NSCLC cell lines resulted in decreased cell size, adhesion, migration, and proliferation. The antiproliferative effect was also confirmed by a reduction in Ki-67 without discernible changes in apoptosis. Collectively, these findings reveal the significant role of ITGA5 in various functional behaviors in NSCLC, providing a potential therapeutic target for NSCLC patients with high ITGA5 expression.

Role of RGD-binding Integrins in ovarian cancer progression, metastasis and response to therapy

Integrins are transmembrane receptors that play a crucial role in cell adhesion and signaling by connecting the extracellular environment to the intracellular cytoskeleton. After binding with specific ligands in the extracellular matrix (ECM), integrins undergo conformational changes that transmit signals across the cell membrane. The integrin-mediated bidirectional signaling triggers various cellular responses, such as changes in cell shape, migration and proliferation. Irregular integrin expression and activity are closely linked to tumor initiation, angiogenesis, cell motility, invasion, and metastasis. Thus, understanding the intricate regulatory mechanism is essential for slowing cancer progression and preventing carcinogenesis. Among the four classes of integrins, the arginine-glycine-aspartic acid (RGD)-binding integrins stand out as the most crucial integrin receptor subfamily in cancer and its metastasis. Dysregulation of almost all RGD-binding integrins promotes ECM degradation in ovarian cancer, resulting in ovarian carcinoma progression and resistance to therapy. Preclinical studies have demonstrated that targeting these integrins with therapeutic antibodies and ligands, such as RGD-containing peptides and their derivatives, can enhance the precision of these therapeutic agents in treating ovarian cancer. Therefore, the development of novel therapeutic agents is essential for treating ovarian cancer. This review mainly discusses genes and their importance across different ovarian cancer subtypes, the involvement of RGD motif-containing ECM proteins in integrin-mediated signaling in ovarian carcinoma, ongoing, completed, partially completed, and unsuccessful clinical trials of therapeutic agents, as well as existing limitations and challenges, advancements made so far, potential strategies, and directions for future research in the field. Insight Box Integrin-mediated signaling regulates cell migration, proliferation and differentiation. Dysregulated integrin expression and activity promote tumor growth and dissemination. Thus, a proper understanding of this complex regulatory mechanism is essential to delay cancer progression and prevent carcinogenesis. Notably, integrins binding to RGD motifs play an important role in tumor initiation, evolution, and metastasis. Preclinical studies have demonstrated that therapeutic agents, such as antibodies and small molecules with RGD motifs, target RGD-binding integrins and disrupt their interactions with the ECM, thereby inhibiting ovarian cancer proliferation and migration. Altogether, this review highlights the potential of RGD-binding integrins in providing new insights into the progression and metastasis of ovarian cancer and how these integrins have been utilized to develop effective treatment plans.

Unraveling the molecular basis for effective regulation of integrin α5β1 for enhanced therapeutic interventions

Cell attachment to the extracellular matrix significantly impacts the integrity of tissues and human health. The integrin α5β1 is a heterodimer of α5 and β1 subunits and has been identified as a crucial modulator in several human carcinomas. Integrin α5β1 significantly regulates cell proliferation, angiogenesis, inflammation, tumor metastasis, and invasion. This regulatory role of integrin α5β1 in tumor metastasis makes it an appealing target for cancer therapy. The majority of the drugs targeting integrin α5β1 are limited only to clinical trials. In our study, we have performed 94287 compounds screening to determine potential drugs against α5β1 integrin. We have used ATN-161 as a reference and employed combined bioinformatic methodologies, including molecular modelling, virtual screening, MM-GBSA, cell-line cytotoxicity prediction, ADMET, Density Functional Theory (DFT), Non-covalent Interactions (NCI) and molecular simulation, to identify putative integrin α5β1 inhibitors. We found Taxifolin, PD133053, and Acebutolol that possess inhibitory activity against α5β1 integrin and could act as effective drug for the cancer treatment. Taxifolin, PD133053, and Acebutolol exhibited excellent binding to the druggable pocket of integrin α5β1, and also maintained a unique binding mechanism with extra hydrophobic contacts at molecular level. Overall, our study gives new pharmacological candidates that may act as a potential drug against integrin α5β1.

Tumor-induced endothelial RhoA activation mediates tumor cell transendothelial migration and metastasis

The endothelial barrier plays an active role in transendothelial tumor cell migration during metastasis, however, the endothelial regulatory elements of this step remain obscure. Here we show that endothelial RhoA activation is a determining factor during this process. Breast tumor cell-induced endothelial RhoA activation is the combined outcome of paracrine IL-8-dependent and cell-to-cell contact β 1 integrin-mediated mechanisms, with elements of this pathway correlating with clinical data. Endothelial-specific RhoA blockade or in vivo deficiency inhibited the transendothelial migration and metastatic potential of human breast tumor and three murine syngeneic tumor cell lines, similar to the pharmacological blockade of the downstream RhoA pathway. These findings highlight endothelial RhoA as a potent, universal target in the tumor microenvironment for anti-metastatic treatment of solid tumors.

Measuring Integrin Force Loading Rates Using a Two-Step DNA Tension Sensor

Cells apply forces to extracellular matrix (ECM) ligands through transmembrane integrin receptors: an interaction which is intimately involved in cell motility, wound healing, cancer invasion and metastasis. These small (piconewton) integrin-ECM forces have been studied by molecular tension fluorescence microscopy (MTFM), which utilizes a force-induced conformational change of a probe to detect mechanical events. MTFM has revealed the force magnitude for integrin receptors in a variety of cell models including primary cells. However, force dynamics and specifically the force loading rate (LR) have important implications in receptor signaling and adhesion formation and remain poorly characterized. Here, we develop an LR probe composed of an engineered DNA structure that undergoes two mechanical transitions at distinct force thresholds: a low force threshold at 4.7 pN (hairpin unfolding) and a high force threshold at 47 pN (duplex shearing). These transitions yield distinct fluorescence signatures observed through single-molecule fluorescence microscopy in live cells. Automated analysis of tens of thousands of events from eight cells showed that the bond lifetime of integrins that engage their ligands and transmit a force >4.7 pN decays exponentially with a τ of 45.6 s. A subset of these events mature in magnitude to >47 pN with a median loading rate of 1.1 pN s-1 and primarily localize at the periphery of the cell-substrate junction. The LR probe design is modular and can be adapted to measure force ramp rates for a broad range of mechanoreceptors and cell models, thus aiding in the study of molecular mechanotransduction in living systems.

Disintegrin Accutin inhibits A549 cell migration though suppression of EMT and FAK/AKT signaling pathway

Integrins are heterodimers composed of two subunits, α(120-185kD) and β (90-110kD), which mediate the connection between cells and their external environment, such as extracellular matrix (ECM), and play an important role in the regulation of cell shape, proliferation and migration. Herein, we identified a potent anti-tumor migration peptide Accutin from crude venom of Agkistrodon acutus using an A549 3D tumor sphere model, and simulation tools and RNA sequencing were performed to reveal the mechanism of Accutin. Accutin is a disintegrin and docking, molecular dynamics simulations and ITC assay indicate that the RGD motif in the Accutin sequence can stably bind to integrins α5β1. 9.22 nM Accutin can significantly inhibit the migration and invasion of lung cancer cell lines. Transcriptome analysis indicated that many genes are involved in tumor cell adhesion-related biological processes. Several pathways, like the "mTOR signaling pathway", "TGF-β signaling pathway", and "Focal adhesion" were enriched. Interestingly, pathways involved in "N-Glycan biosynthesis" etc. were significantly inhibited. These transcriptomics data suggested that the molecular basis of Accutin-mediated inhibition of cancer cell migration may be by inhibiting N-glycosylation of integrin, then inhibiting signaling pathways such as PI3K/AKT/mTOR and TGFβ/smad. Western blotting analysis further confirmed that Accutin could suppress migration via down-regulating the phosphorylation of FAK and AKT and inhibiting EMT (epithelial-mesenchymal transition). Taken together, as a disintegrin with high efficiency, Accutin may be a potential precursor of a therapeutic agent for the treatment of lung cancer migration.

Development of a Bladder Cancer-on-a-Chip Model to Assess Bladder Cancer Cell Invasiveness

We have developed a bladder cancer-on-a-chip model which supports the 3D growth of cells and can be used to assess and quantify bladder cancer cell invasiveness in a physiologically appropriate environment. Three bladder cancer cell lines (T24, J82, and RT4) were resuspended in 50% Matrigel® and grown within a multi-channel organ-on-a-chip system. The ability of live cells to invade across into an adjacent 50% Matrigel®-only channel was assessed over a 2-day period. Cell lines isolated from patients with high-grade bladder cancer (T24 and J82) invaded across into the Matrigel®-only channel at a much higher frequency compared to cells isolated from a patient with low-grade cancer (RT4) (p < 0.001). The T24 and J82 cells also invaded further distances into the Matrigel®-only channel compared to the RT4 cells (p < 0.001). The cell phenotype within the model was maintained as assessed by cell morphology and immunohistochemical analysis of E-cadherin. Treatment with ATN-161, an α5β1 integrin inhibitor and well-known migrastatic drug, caused a dose-dependent decrease in the invasiveness of the J82 cells (p < 0.01). The combined data demonstrate that our bladder cancer-on-a-chip model supports the retention of the bladder cancer cell phenotype and can be used to reproducibly assess and quantify the invasiveness of live bladder cancer cells.

Cellular elasticity in cancer: a review of altered biomechanical features

A large number of studies have shown that changes in biomechanical characteristics are an important indicator of tumor transformation in normal cells. Elastic deformation is one of the more studied biomechanical features of tumor cells, which plays an important role in tumourigenesis and development. Altered cell elasticity often brings many indications. This manuscript reviews the effects of altered cellular elasticity on cell characteristics, including adhesion viscosity, migration, proliferation, and differentiation elasticity and stiffness. Also, the physical factors that may affect cell elasticity, such as temperature, cell height, cell-viscosity, and aging, are summarized. Then, the effects of cell-matrix, cytoskeleton, in vitro culture medium, and cell-substrate with different three-dimensional structures on cell elasticity during cell tumorigenesis are outlined. Importantly, we summarize the current signaling pathways that may affect cellular elasticity, as well as tests for cellular elastic deformation. Finally, we summarize current hybrid materials: polymer-polymer, protein-protein, and protein-polymer hybrids, also, nano-delivery strategies that target cellular resilience and cases that are at least in clinical phase 1 trials. Overall, the behavior of cancer cell elasticity is modulated by biological, chemical, and physical changes, which in turn have the potential to alter cellular elasticity, and this may be an encouraging prediction for the future discovery of cancer therapies.

Myoglobin Inhibits Breast Cancer Cell Fatty Acid Oxidation and Migration via Heme-dependent Oxidant Production and Not Fatty Acid Binding

The monomeric heme protein myoglobin (Mb), traditionally thought to be expressed exclusively in cardiac and skeletal muscle, is now known to be expressed in approximately 40% of breast tumors. While Mb expression is associated with better patient prognosis, the molecular mechanisms by which Mb limits cancer progression are unclear. In muscle, Mb's predominant function is oxygen storage and delivery, which is dependent on the protein's heme moiety. However, prior studies demonstrate that the low levels of Mb expressed in cancer cells preclude this function. Recent studies propose a novel fatty acid binding function for Mb via a lysine residue (K46) in the heme pocket. Given that cancer cells can upregulate fatty acid oxidation (FAO) to maintain energy production for cytoskeletal remodeling during cell migration, we tested whether Mb-mediated fatty acid binding modulates FAO to decrease breast cancer cell migration. We demonstrate that the stable expression of human Mb in MDA-MB-231 breast cancer cells decreases cell migration and FAO. Site-directed mutagenesis of Mb to disrupt Mb fatty acid binding did not reverse Mb-mediated attenuation of FAO or cell migration in these cells. In contrast, cells expressing Apo-Mb, in which heme incorporation was disrupted, showed a reversal of Mb-mediated attenuation of FAO and cell migration, suggesting that Mb attenuates FAO and migration via a heme-dependent mechanism rather than through fatty acid binding. To this end, we show that Mb's heme-dependent oxidant generation propagates dysregulated gene expression of migratory genes, and this is reversed by catalase treatment. Collectively, these data demonstrate that Mb decreases breast cancer cell migration, and this effect is due to heme-mediated oxidant production rather than fatty acid binding. The implication of these results will be discussed in the context of therapeutic strategies to modulate oxidant production and Mb in tumors.

Highlights

Myoglobin (Mb) expression in MDA-MB-231 breast cancer cells slows migration.Mb expression decreases mitochondrial respiration and fatty acid oxidation.Mb-dependent fatty acid binding does not regulate cell migration or respiration.Mb-dependent oxidant generation decreases mitochondrial metabolism and migration.Mb-derived oxidants dysregulate migratory gene expression.

Natural Killer Cell Mechanosensing in Solid Tumors

Natural killer (NK) cells, which are an exciting alternative cell source for cancer immunotherapies, must sense and respond to their physical environment to traffic to and eliminate cancer cells. Herein, we review the mechanisms by which NK cells receive mechanical signals and explore recent key findings regarding the impact of the physical characteristics of solid tumors on NK cell functions. Data suggest that different mechanical stresses present in solid tumors facilitate NK cell functions, especially infiltration and degranulation. Moreover, we review recent engineering advances that can be used to systemically study the role of mechanical forces on NK cell activity. Understanding the mechanisms by which NK cells interpret their environment presents potential targets to enhance NK cell immunotherapies for the treatment of solid tumors.

Measuring integrin force loading rates using a two-step DNA tension sensor

Cells apply forces to extracellular matrix (ECM) ligands through transmembrane integrin receptors: an interaction which is intimately involved in cell motility, wound healing, cancer invasion and metastasis. These small (pN) forces exerted by cells have been studied by molecular tension fluorescence microscopy (MTFM), which utilizes a force-induced conformational change of a probe to detect mechanical events. MTFM has revealed the force magnitude for integrins receptors in a variety of cell models including primary cells. However, force dynamics and specifically the force loading rate (LR) have important implications in receptor signaling and adhesion formation and remain poorly characterized. Here, we develop a LR probe which is comprised of an engineered DNA structures that undergoes two mechanical transitions at distinct force thresholds: a low force threshold at 4.7 pN corresponding to hairpin unfolding and a high force threshold at 56 pN triggered through duplex shearing. These transitions yield distinct fluorescence signatures observed through single-molecule fluorescence microscopy in live-cells. Automated analysis of tens of thousands of events from 8 cells showed that the bond lifetime of integrins that engage their ligands and transmit a force >4.7 pN decays exponentially with a τ of 45.6 sec. A small subset of these events (<10%) mature in magnitude to >56pN with a median loading rate of 1.3 pNs-1 with these mechanical ramp events localizing at the periphery of the cell-substrate junction. Importantly, the LR probe design is modular and can be adapted to measure force ramp rates for a broad range of mechanoreceptors and cell models, thus aiding in the study of mechanotransduction.

Phenotypic Heterogeneity, Bidirectionality, Universal Cues, Plasticity, Mechanics, and the Tumor Microenvironment Drive Cancer Metastasis

Tumor diseases become a huge problem when they embark on a path that advances to malignancy, such as the process of metastasis. Cancer metastasis has been thoroughly investigated from a biological perspective in the past, whereas it has still been less explored from a physical perspective. Until now, the intraluminal pathway of cancer metastasis has received the most attention, while the interaction of cancer cells with macrophages has received little attention. Apart from the biochemical characteristics, tumor treatments also rely on the tumor microenvironment, which is recognized to be immunosuppressive and, as has recently been found, mechanically stimulates cancer cells and thus alters their functions. The review article highlights the interaction of cancer cells with other cells in the vascular metastatic route and discusses the impact of this intercellular interplay on the mechanical characteristics and subsequently on the functionality of cancer cells. For instance, macrophages can guide cancer cells on their intravascular route of cancer metastasis, whereby they can help to circumvent the adverse conditions within blood or lymphatic vessels. Macrophages induce microchannel tunneling that can possibly avoid mechanical forces during extra- and intravasation and reduce the forces within the vascular lumen due to vascular flow. The review article highlights the vascular route of cancer metastasis and discusses the key players in this traditional route. Moreover, the effects of flows during the process of metastasis are presented, and the effects of the microenvironment, such as mechanical influences, are characterized. Finally, the increased knowledge of cancer metastasis opens up new perspectives for cancer treatment.

Overexpression of the adhesion signaling pathway is linked to short-term survival in pancreatic ductal adenocarcinoma

BACKGROUND AND OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is known for its unfavorable prognosis. Gaining insights into the molecular mechanisms that contribute to its progression is crucial for developing effective therapies. In this study, our objective was to investigate the molecular pathways associated with short-term survival in patients with PDAC.

METHODS

Immune profiles were analyzed from both long-term survivors (n = 10) and short-term survivors (n = 10) after surgical resection. Pathway scores were calculated to compare the two groups.

RESULTS

The "Adhesion" pathway emerged as the most significant pathway, exhibiting a notably higher score in the samples of short-term survivors (P < 0.009). Within this pathway, significant findings were observed in genes related to integrins and CEACAM.

CONCLUSION

The role of integrins in the tumor microenvironment of pancreatic cancer is of utmost importance, as they are found to be overexpressed in short-term survivors. These findings provide valuable insights into the underlying biology of PDAC and have potential implications for the development of therapeutic strategies.

Adhesion, metastasis, and inhibition of cancer cells: a comprehensive review

This comprehensive review delves into cancer's complexity, focusing on adhesion, metastasis, and inhibition. It explores the pivotal role of these factors in disease progression and therapeutic strategies. This review covers cancer cell migration, invasion, and colonization of distant organs, emphasizing the significance of cell adhesion and the intricate metastasis process. Inhibition approaches targeting adhesion molecules, such as integrins and cadherins, are discussed. Overall, this review contributes significantly to advancing cancer research and developing targeted therapies, holding promise for improving patient outcomes worldwide. Exploring different inhibition strategies revealed promising therapeutic targets to alleviate adhesion and metastasis of cancer cells. The effectiveness of integrin-blocking antibodies, small molecule inhibitors targeting Focal adhesion kinase (FAK) and the Transforming Growth Factor β (TGF-β) pathway, and combination therapies underscores their potential to disrupt focal adhesions and control epithelial-mesenchymal transition processes. The identification of as FAK, Src, β-catenin and SMAD4 offers valuable starting points for further research and the development of targeted therapies. The complex interrelationships between adhesion and metastatic signaling networks will be relevant to the development of new treatment approaches.

ITGB1 and DDR activation as novel mediators in acquired resistance to osimertinib and MEK inhibitors in EGFR-mutant NSCLC

Osimertinib is a third-generation tyrosine kinase inhibitor clinically approved for first-line treatment of EGFR-mutant non-small cell lung cancer (NSCLC) patients. Although an impressive drug response is initially observed, in most of tumors, resistance occurs after different time and an alternative therapeutic strategy to induce regression disease is currently lacking. The hyperactivation of MEK/MAPKs, is one the most common event identified in osimertinib-resistant (OR) NSCLC cells. However, in response to selective drug pressure, the occurrence of multiple mechanisms of resistance may contribute to treatment failure. In particular, the epithelial-to-mesenchymal transition (EMT) and the impaired DNA damage repair (DDR) pathways are recognized as additional cause of resistance in NSCLC thus promoting tumor progression. Here we showed that concurrent upregulation of ITGB1 and DDR family proteins may be associated with an increase of EMT pathways and linked to both osimertinib and MEK inhibitor resistance to cell death. Furthermore, this study demonstrated the existence of an interplay between ITGB1 and DDR and highlighted, for the first time, that combined treatment of MEK inhibitor with DDRi may be relevant to downregulate ITGB1 levels and increase cell death in OR NSCLC cells.

Extracellular Matrix Cues Regulate Mechanosensing and Mechanotransduction of Cancer Cells

Extracellular biophysical properties have particular implications for a wide spectrum of cellular behaviors and functions, including growth, motility, differentiation, apoptosis, gene expression, cell-matrix and cell-cell adhesion, and signal transduction including mechanotransduction. Cells not only react to unambiguously mechanical cues from the extracellular matrix (ECM), but can occasionally manipulate the mechanical features of the matrix in parallel with biological characteristics, thus interfering with downstream matrix-based cues in both physiological and pathological processes. Bidirectional interactions between cells and (bio)materials in vitro can alter cell phenotype and mechanotransduction, as well as ECM structure, intentionally or unintentionally. Interactions between cell and matrix mechanics in vivo are of particular importance in a variety of diseases, including primarily cancer. Stiffness values between normal and cancerous tissue can range between 500 Pa (soft) and 48 kPa (stiff), respectively. Even the shear flow can increase from 0.1-1 dyn/cm2 (normal tissue) to 1-10 dyn/cm2 (cancerous tissue). There are currently many new areas of activity in tumor research on various biological length scales, which are highlighted in this review. Moreover, the complexity of interactions between ECM and cancer cells is reduced to common features of different tumors and the characteristics are highlighted to identify the main pathways of interaction. This all contributes to the standardization of mechanotransduction models and approaches, which, ultimately, increases the understanding of the complex interaction. Finally, both the in vitro and in vivo effects of this mechanics-biology pairing have key insights and implications for clinical practice in tumor treatment and, consequently, clinical translation.

RGD peptide in cancer targeting: Benefits, challenges, solutions, and possible integrin-RGD interactions

RGD peptide can be found in cell adhesion and signaling proteins, such as fibronectin, vitronectin, and fibrinogen. RGD peptides' principal function is to facilitate cell adhesion by interacting with integrin receptors on the cell surface. They have been intensively researched for use in biotechnology and medicine, including incorporation into biomaterials, conjugation to medicinal molecules or nanoparticles, and labeling with imaging agents. RGD peptides can be utilized to specifically target cancer cells and the tumor vasculature by engaging with these integrins, improving drug delivery efficiency and minimizing adverse effects on healthy tissues. RGD-functionalized drug carriers are a viable option for cancer therapy as this focused approach has demonstrated promise in the future. Writing a review on the RGD peptide can significantly influence how drugs are developed in the future by improving our understanding of the peptide, finding knowledge gaps, fostering innovation, and making drug design easier.

Biophysics in tumor growth and progression: from single mechano-sensitive molecules to mechanomedicine

Evidence from physical sciences in oncology increasingly suggests that the interplay between the biophysical tumor microenvironment and genetic regulation has significant impact on tumor progression. Especially, tumor cells and the associated stromal cells not only alter their own cytoskeleton and physical properties but also remodel the microenvironment with anomalous physical properties. Together, these altered mechano-omics of tumor tissues and their constituents fundamentally shift the mechanotransduction paradigms in tumorous and stromal cells and activate oncogenic signaling within the neoplastic niche to facilitate tumor progression. However, current findings on tumor biophysics are limited, scattered, and often contradictory in multiple contexts. Systematic understanding of how biophysical cues influence tumor pathophysiology is still lacking. This review discusses recent different schools of findings in tumor biophysics that have arisen from multi-scale mechanobiology and the cutting-edge technologies. These findings range from the molecular and cellular to the whole tissue level and feature functional crosstalk between mechanotransduction and oncogenic signaling. We highlight the potential of these anomalous physical alterations as new therapeutic targets for cancer mechanomedicine. This framework reconciles opposing opinions in the field, proposes new directions for future cancer research, and conceptualizes novel mechanomedicine landscape to overcome the inherent shortcomings of conventional cancer diagnosis and therapies.

Migration speed of captured breast cancer subpopulations correlates with metastatic fitness

The genetic alterations contributing to migration proficiency, a phenotypic hallmark of metastatic cells required for colonizing distant organs, remain poorly defined. Here, we used single-cell magneto-optical capture (scMOCa) to isolate fast cells from heterogeneous human breast cancer cell populations, based on their migratory ability alone. We show that captured fast cell subpopulations retain higher migration speed and focal adhesion dynamics over many generations as a result of a motility-related transcriptomic profile. Upregulated genes in isolated fast cells encoded integrin subunits, proto-cadherins and numerous other genes associated with cell migration. Dysregulation of several of these genes correlates with poor survival outcomes in people with breast cancer, and primary tumors established from fast cells generated a higher number of circulating tumor cells and soft tissue metastases in pre-clinical mouse models. Subpopulations of cells selected for a highly migratory phenotype demonstrated an increased fitness for metastasis.

Integrins in cancer: Emerging mechanisms and therapeutic opportunities

Integrins are vital surface adhesion receptors that mediate the interactions between the extracellular matrix (ECM) and cells and are essential for cell migration and the maintenance of tissue homeostasis. Aberrant integrin activation promotes initial tumor formation, growth, and metastasis. Recently, many lines of evidence have indicated that integrins are highly expressed in numerous cancer types and have documented many functions of integrins in tumorigenesis. Thus, integrins have emerged as attractive targets for the development of cancer therapeutics. In this review, we discuss the underlying molecular mechanisms by which integrins contribute to most of the hallmarks of cancer. We focus on recent progress on integrin regulators, binding proteins, and downstream effectors. We highlight the role of integrins in the regulation of tumor metastasis, immune evasion, metabolic reprogramming, and other hallmarks of cancer. In addition, integrin-targeted immunotherapy and other integrin inhibitors that have been used in preclinical and clinical studies are summarized.

Mechanistic insights into the development of severe fetal growth restriction

Fetal growth restriction (FGR), which most commonly results from suboptimal placental function, substantially increases risks for adverse perinatal and long-term outcomes. The only "treatment" that exists is delivery, which averts stillbirth but does not improve outcomes in survivors. Furthermore, the potential long-term consequences of FGR to the fetus, including cardiometabolic disorders, predispose these individuals to developing FGR in their future pregnancies. This creates a multi-generational cascade of adverse effects stemming from a single dysfunctional placenta, and understanding the mechanisms underlying placental-mediated FGR is critically important if we are to improve outcomes and overall health. The mechanisms behind FGR remain unknown. However, placental insufficiency derived from maldevelopment of the placental vascular systems is the most common etiology. To highlight important mechanistic interactions within the placenta, we focus on placental vascular development in the setting of FGR. We delve into fetoplacental angiogenesis, a robust and ongoing process in normal pregnancies that is impaired in severe FGR. We review cellular models of FGR, with special attention to fetoplacental angiogenesis, and we highlight novel integrin-extracellular matrix interactions that regulate placental angiogenesis in severe FGR. In total, this review focuses on key developmental processes, with specific focus on the human placenta, an underexplored area of research.

Strain-dependent elastography of cancer cells reveals heterogeneity and stiffening due to attachment

Because cells vary in thickness and in biomechanical properties, the use of a constant force trigger during atomic force microscopy (AFM) stiffness mapping produces a varied nominal strain that can obfuscate the comparison of local material properties. In this study, we measured the biomechanical spatial heterogeneity of ovarian and breast cancer cells by using an indentation-dependent pointwise Hertzian method. Force curves and surface topography were used together to determine cell stiffness as a function of nominal strain. By recording stiffness at a particular strain, it may be possible to improve comparison of the material properties of cells and produce higher contrast representations of cell mechanical properties. Defining a linear region of elasticity that corresponds to a modest nominal strain, we were able to clearly distinguish the mechanics of the perinuclear region of cells. We observed that, relative to the lamelopodial stiffness, the perinuclear region was softer for metastatic cancer cells than their nonmetastatic counterparts. Moreover, contrast in the strain-dependent elastography in comparison to conventional force mapping with Hertzian model analysis revealed a significant stiffening phenomenon in the thin lamellipodial region in which the modulus scales inversely and exponentially with cell thickness. The observed exponential stiffening is not affected by relaxation of cytoskeletal tension, but finite element modeling indicates it is affected by substrate adhesion. The novel cell mapping technique explores cancer cell mechanical nonlinearity that results from regional heterogeneity, which could help explain how metastatic cancer cells can show soft phenotypes while simultaneously increasing force generation and invasiveness.

Physical and biological advances in endothelial cell-based engineered co-culture model systems

Scientific knowledge in the field of cell biology and mechanobiology heavily leans on cell-based in vitro experiments and models that favor the examination and comprehension of certain biological processes and occurrences across a variety of environments. Cell culture assays are an invaluable instrument for a vast spectrum of biomedical and biophysical investigations. The quality of experimental models in terms of simplicity, reproducibility, and combinability with other methods, and in particular the scale at which they depict cell fate in native tissues, is critical to advancing the knowledge of the comprehension of cell-cell and cell-matrix interactions in tissues and organs. Typically, in vitro models are centered on the experimental tinkering of mammalian cells, most often cultured as monolayers on planar, two-dimensional (2D) materials. Notwithstanding the significant advances and numerous findings that have been accomplished with flat biology models, their usefulness for generating further new biological understanding is constrained because the simple 2D setting does not reproduce the physiological response of cells in natural living tissues. In addition, the co-culture systems in a 2D stetting weakly mirror their natural environment of tissues and organs. Significant advances in 3D cell biology and matrix engineering have resulted in the creation and establishment of a new type of cell culture shapes that more accurately represents the in vivo microenvironment and allows cells and their interactions to be analyzed in a biomimetic approach. Contemporary biomedical and biophysical science has novel advances in technology that permit the design of more challenging and resilient in vitro models for tissue engineering, with a particular focus on scaffold- or hydrogel-based formats, organotypic cultures, and organs-on-chips, which cover the purposes of co-cultures. Even these complex systems must be kept as simplified as possible in order to grasp a particular section of physiology too very precisely. In particular, it is highly appreciated that they bridge the space between conventional animal research and human (patho)physiology. In this review, the recent progress in 3D biomimetic culturation is presented with a special focus on co-cultures, with an emphasis on the technological building blocks and endothelium-based co-culture models in cancer research that are available for the development of more physiologically relevant in vitro models of human tissues under normal and diseased conditions. Through applications and samples of various physiological and disease models, it is possible to identify the frontiers and future engagement issues that will have to be tackled to integrate synthetic biomimetic culture systems far more successfully into biomedical and biophysical investigations.

The interaction of β-arrestin1 with talin1 driven by endothelin A receptor as a feature of α5β1 integrin activation in high-grade serous ovarian cancer

Dissemination of high-grade serous ovarian cancer (HG-SOC) in the omentum and intercalation into a mesothelial cell (MC) monolayer depends on functional α5β1 integrin (Intα5β1) activity. Although the binding of Intα5β1 to fibronectin drives these processes, other molecular mechanisms linked to integrin inside-out signaling might support metastatic dissemination. Here, we report a novel interactive signaling that contributes to Intα5β1 activation and accelerates tumor cells toward invasive disease, involving the protein β-arrestin1 (β-arr1) and the activation of the endothelin A receptor (ETAR) by endothelin-1 (ET-1). As demonstrated in primary HG-SOC cells and SOC cell lines, ET-1 increased Intβ1 and downstream FAK/paxillin activation. Mechanistically, β-arr1 directly interacts with talin1 and Intβ1, promoting talin1 phosphorylation and its recruitment to Intβ1, thus fueling integrin inside-out activation. In 3D spheroids and organotypic models mimicking the omentum, ETAR/β-arr1-driven Intα5β1 signaling promotes the survival of cell clusters, with mesothelium-intercalation capacity and invasive behavior. The treatment with the antagonist of ETAR, Ambrisentan (AMB), and of Intα5β1, ATN161, inhibits ET-1-driven Intα5β1 activity in vitro, and tumor cell adhesion and spreading to intraperitoneal organs and Intβ1 activity in vivo. As a prognostic factor, high EDNRA/ITGB1 expression correlates with poor HG-SOC clinical outcomes. These findings highlight a new role of ETAR/β-arr1 operating an inside-out integrin activation to modulate the metastatic process and suggest that in the new integrin-targeting programs might be considered that ETAR/β-arr1 regulates Intα5β1 functional pathway.

Cell-adhesion Molecules as Key Mechanisms of Tumor Invasion: The Case of Breast Cancer

Cancer is a major health problem worldwide and the second leading cause of death following cardiovascular diseases. Breast cancer is the leading cause of mortality and morbidity among women and one of the most common malignant neoplasms prompt to metastatic disease. In the present review, the mechanisms of the major cell adhesion molecules involved in tumor invasion are discussed, focusing on the case of breast cancer. A non-systematic updated revision of the literature was performed in order to assemble information regarding the expression of the adhesion cell molecules associated with metastasis.

Inhibition of Metastasis by Polypyridyl Ru(II) Complexes through Modification of Cancer Cell Adhesion - In Vitro Functional and Molecular Studies

The effect of polypyridyl Ru(II) complexes on the ability of cancer cells to migrate and invade, two features important in the formation of metastases, is evaluated. In vitro studies are carried out on breast cancer cell lines, MDA-MB-231 and MCF-7, as well as melanoma cell lines A2058 and A375. Three Ru(II) complexes comprising two 4,7-diphenyl-1,10-phenanthroline (dip) ligands and as a third ligand 2,2′-bipyridine (bpy), or its derivative with either 4-[3-(2-nitro-1H-imidazol-1-yl)propyl] (bpy-NitroIm), or 5-(4-{4′-methyl-[2,2′-bipyridine]-4-yl}but-1-yn-1-yl)pyridine-2-carbaldehyde semicarbazone (bpy-SC) moiety attached are examined. The low sub-toxic doses of the studied compounds greatly affected the cancer cells by inhibiting cell detachment, migration, invasion, transmigration, and re-adhesion, as well as increasing cell elasticity. The molecular studies revealed that the Ru(II) polypyridyl complexes impact the activity of the selected integrins and upregulate the expression of focal adhesion components such as vinculin and paxillin, leading to an increased number of focal adhesion contacts.

PINCH1 Promotes Fibroblast Migration in Extracellular Matrices and Influences Their Mechanophenotype

Cell migration performs a critical function in numerous physiological processes, including tissue homeostasis or wound healing after tissue injury, as well as pathological processes that include malignant progression of cancer. The efficiency of cell migration and invasion appears to be based on the mechano-phenotype of the cytoskeleton. The properties of the cytoskeleton depend on internal cytoskeletal and external environmental factors. A reason for this are connections between the cell and its local matrix microenvironment, which are established by cell-matrix adhesion receptors. Upon activation, focal adhesion proteins such as PINCH1 are recruited to sites where focal adhesions form. PINCH1 specifically couples through interactions with ILK, which binds to cell matrix receptors and the actomyosin cytoskeleton. However, the role of PINCH1 in cell mechanics regulating cellular motility in 3D collagen matrices is still unclear. PINCH1 is thought to facilitate 3D motility by regulating cellular mechanical properties, such as stiffness. In this study, PINCH1 wild-type and knock-out cells were examined for their ability to migrate in dense extracellular 3D matrices. Indeed, PINCH1 wild-type cells migrated more numerously and deeper in 3D matrices, compared to knock-out cells. Moreover, cellular deformability was determined, e.g., elastic modulus (stiffness). PINCH1 knock-out cells are more deformable (compliable) than PINCH1 wild-type cells. Migration of both PINCH1−/− cells and PINCH1fl/fl cells was decreased by Latrunculin A inhibition of actin polymerization, suggesting that actin cytoskeletal differences are not responsible for the discrepancy in invasiveness of the two cell types. However, the mechanical phenotype of PINCH1−/− cells may be reflected by Latrunculin A treatment of PINCH1fl/fl cells, as they exhibit resembling deformability to untreated PINCH1−/− cells. Moreover, an apparent mismatch exists between the elongation of the long axis and the contraction of the short axis between PINCH1fl/fl cells and PINCH1−/− cells following Latrunculin A treatment. There is evidence of this indicating a shift in the proxy values for Poisson’s ratio in PINCH1−/− cells compared with PINCH1fl/fl cells. This is probably attributable to modifications in cytoskeletal architecture. The non-muscle myosin II inhibitor Blebbistatin also reduced the cell invasiveness in 3D extracellular matrices but instead caused a stiffening of the cells. Finally, PINCH1 is apparently essential for providing cellular mechanical stiffness through the actin cytoskeleton, which regulates 3D motility.

Sticking around: Cell adhesion patterning for energy minimization and substrate mechanosensing

Tissue stiffness (Young's modulus) is a key control parameter in cell behavior and bioengineered gels where defined mechanical properties have become an essential part of the toolkit for interrogating mechanotransduction. Here, we show using a mechanical cell model that the effective substrate stiffness experienced by a cell depends, not just on the engineered mechanical properties of the substrate but critically also on the particular arrangement of adhesions between cell and substrate. In particular, we find that cells with different adhesion patterns can experience two different gel stiffnesses as equivalent and will generate the same mean cell deformations. In considering small patches of adhesion, which mimic focal adhesion complexes, we show how the experimentally observed focal adhesion growth and elongation on stiff substrates can be explained by energy considerations. Relatedly, energy arguments also provide a reason why nascent adhesions do not establish into focal adhesions on soft substrates, as has been commonly observed. Fewer and larger adhesions are predicted to be preferred over more and smaller, an effect enhanced by random spot placing with the simulations predicting qualitatively realistic cell shapes in this case.

Morphological Phenotyping of Organotropic Brain- and Bone-Seeking Triple Negative Metastatic Breast Tumor Cells

Triple negative breast cancer (TNBC) follows a non-random pattern of metastasis to the bone and brain tissue. Prior work has found that brain-seeking breast tumor cells display altered proteomic profiles, leading to alterations in pathways related to cell signaling, cell cycle, metabolism, and extracellular matrix remodeling. Given the unique microenvironmental characteristics of brain and bone tissue, we hypothesized that brain- or bone-seeking TNBC cells may have altered morphologic or migratory phenotypes from each other, or from the parental TNBC cells, as a function of the biochemical or mechanical microenvironment. In this study, we utilized TNBC cells (MDA-MB-231) that were conditioned to metastasize solely to brain (MDA-BR) or bone (MDA-BO) tissue. We quantified characteristics such as cell morphology, migration, and stiffness in response to cues that partially mimic their final metastatic niche. We have shown that MDA-BO cells have a distinct protrusive morphology not found in MDA-P or MDA-BR. Further, MDA-BO cells migrate over a larger area when on a collagen I (abundant in bone tissue) substrate when compared to fibronectin (abundant in brain tissue). However, migration in highly confined environments was similar across the cell types. Modest differences were found in the stiffness of MDA-BR and MDA-BO cells plated on collagen I vs. fibronectin-coated surfaces. Lastly, MDA-BO cells were found to have larger focal adhesion area and density in comparison with the other two cell types. These results initiate a quantitative profile of mechanobiological phenotypes in TNBC, with future impacts aiming to help predict metastatic propensities to organ-specific sites in a clinical setting.

Viscoelasticity, Like Forces, Plays a Role in Mechanotransduction

Viscoelasticity and its alteration in time and space has turned out to act as a key element in fundamental biological processes in living systems, such as morphogenesis and motility. Based on experimental and theoretical findings it can be proposed that viscoelasticity of cells, spheroids and tissues seems to be a collective characteristic that demands macromolecular, intracellular component and intercellular interactions. A major challenge is to couple the alterations in the macroscopic structural or material characteristics of cells, spheroids and tissues, such as cell and tissue phase transitions, to the microscopic interferences of their elements. Therefore, the biophysical technologies need to be improved, advanced and connected to classical biological assays. In this review, the viscoelastic nature of cytoskeletal, extracellular and cellular networks is presented and discussed. Viscoelasticity is conceptualized as a major contributor to cell migration and invasion and it is discussed whether it can serve as a biomarker for the cells' migratory capacity in several biological contexts. It can be hypothesized that the statistical mechanics of intra- and extracellular networks may be applied in the future as a powerful tool to explore quantitatively the biomechanical foundation of viscoelasticity over a broad range of time and length scales. Finally, the importance of the cellular viscoelasticity is illustrated in identifying and characterizing multiple disorders, such as cancer, tissue injuries, acute or chronic inflammations or fibrotic diseases.

The role of the tendon ECM in mechanotransduction: disruption and repair following overuse

Purpose: Tendon overuse injuries are prevalent conditions with limited therapeutic options to halt disease progression. The specialized extracellular matrix (ECM) both enables joint function and mediates mechanical signals to tendon cells, driving biological responses to exercise or injury. With overuse, tendon ECM composition and structure changes at multiple scales, disrupting mechanotransduction and resulting in inadequate repair and disease progression. This review highlights the multiscale ECM changes that occur with tendon overuse and corresponding effects on cell-matrix interactions and cellular response to load.Results: Different functional joint requirements and tendon types experience a wide range of loading profiles, creating varied downstream mechanical stimuli. Distinct ECM structure and mechanical properties within the fascicle matrix, interfascicle matrix, and enthesis and their varied disruption with overuse are considered. The pericellular matrix (PCM) comprising the microscale tendon cell environment has a unique composition that changes with overuse injury and exercise, suggesting an important role in mechanotransduction and promoting repair. Cell-matrix interactions are mediated by structures including cilia, integrins, connexins and cytoskeleton that signal downstream homeostasis, adaptation, or repair. ECM disruption with tendon overuse may cause altered mechanical loading and cell-matrix interactions, resulting in mechanobiological understimulation, apoptosis, and ineffective repair. Current interventions to promote repair of tendon overuse injuries including exercise, targeting cell signaling, and modulating inflammation are considered.Conclusion: Future therapeutics should be assessed with regard of their effects on multiscale mechanotransduction in addition to joint function, with consideration of the central role of ECM.

Tumor Microenvironment in Pancreatic Intraepithelial Neoplasia

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive neoplasm with a poor survival rate. This is mainly due to late detection, which substantially limits therapy options. A better understanding of the early phases of pancreatic carcinogenesis is fundamental for improving patient prognosis in the future. In this article, we focused on the tumor microenvironment (TME), which provides the biological niche for the development of PDAC from its most common precursor lesions, PanIN (pancreatic intraepithelial neoplasias).

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive tumors with a poor prognosis. A characteristic of PDAC is the formation of an immunosuppressive tumor microenvironment (TME) that facilitates bypassing of the immune surveillance. The TME consists of a desmoplastic stroma, largely composed of cancer-associated fibroblasts (CAFs), immunosuppressive immune cells, immunoregulatory soluble factors, neural network cells, and endothelial cells with complex interactions. PDAC develops from various precursor lesions such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasms (IPMN), mucinous cystic neoplasms (MCN), and possibly, atypical flat lesions (AFL). In this review, we focus on the composition of the TME in PanINs to reveal detailed insights into the complex restructuring of the TME at early time points in PDAC progression and to explore ways of modifying the TME to slow or even halt tumor progression.

Advanced quantification for single-cell adhesion by variable-angle TIRF nanoscopy

Over the last decades, several techniques have been developed to study cell adhesion; however, they present significant shortcomings. Such techniques mostly focus on strong adhesion related to specific protein-protein associations, such as ligand-receptor binding in focal adhesions. Therefore, weak adhesion, related to less specific or nonspecific cell-substrate interactions, are rarely addressed. Hence, we propose in this work a complete investigation of cell adhesion, from highly specific to nonspecific adhesiveness, using variable-angle total internal reflection fluorescence (vaTIRF) nanoscopy. This technique allows us to map in real time cell topography with a nanometric axial resolution, along with cell cortex refractive index. These two key parameters allow us to distinguish high and low adhesive cell-substrate contacts. Furthermore, vaTIRF provides cell-substrate binding energy, thus revealing a correlation between cell contractility and cell-substrate binding energy. Here, we highlight the quantitative measurements achieved by vaTIRF on U87MG glioma cells expressing different amounts of α ₅ integrins and distinct motility on fibronectin. Regarding integrin expression level, data extracted from vaTIRF measurements, such as the number and size of high adhesive contacts per cell, corroborate the adhesiveness of U87MG cells as intended. Interestingly enough, we found that cells overexpressing α ₅ integrins present a higher contractility and lower adhesion energy.

Viscoelasticity Acts as a Marker for Tumor Extracellular Matrix Characteristics

Biological materials such as extracellular matrix scaffolds, cancer cells, and tissues are often assumed to respond elastically for simplicity; the viscoelastic response is quite commonly ignored. Extracellular matrix mechanics including the viscoelasticity has turned out to be a key feature of cellular behavior and the entire shape and function of healthy and diseased tissues, such as cancer. The interference of cells with their local microenvironment and the interaction among different cell types relies both on the mechanical phenotype of each involved element. However, there is still not yet clearly understood how viscoelasticity alters the functional phenotype of the tumor extracellular matrix environment. Especially the biophysical technologies are still under ongoing improvement and further development. In addition, the effect of matrix mechanics in the progression of cancer is the subject of discussion. Hence, the topic of this review is especially attractive to collect the existing endeavors to characterize the viscoelastic features of tumor extracellular matrices and to briefly highlight the present frontiers in cancer progression and escape of cancers from therapy. Finally, this review article illustrates the importance of the tumor extracellular matrix mechano-phenotype, including the phenomenon viscoelasticity in identifying, characterizing, and treating specific cancer types.

Denis N, Gingras AC, Lukacs GL, Pause A. Endofin is required for HD-PTP and ESCRT-0 interdependent endosomal sorting of ubiquitinated transmembrane cargoes

Internalized and ubiquitinated signaling receptors are silenced by their intraluminal budding into multivesicular bodies aided by the endosomal sorting complexes required for transport (ESCRT) machinery. HD-PTP, an ESCRT protein, forms complexes with ESCRT-0, -I and -III proteins, and binds to Endofin, a FYVE-domain protein confined to endosomes with poorly understood roles. Using proximity biotinylation, we showed that Endofin forms a complex with ESCRT constituents and Endofin depletion increased integrin α5-and EGF-receptor plasma membrane density and stability by hampering their lysosomal delivery. This coincided with sustained receptor signaling and increased cell migration. Complementation of Endofin- or HD-PTP-depleted cells with wild-type Endofin or HD-PTP, but not with mutants harboring impaired Endofin/HD-PTP association or cytosolic Endofin, restored EGFR lysosomal delivery. Endofin also promoted Hrs indirect interaction with HD-PTP. Jointly, our results indicate that Endofin is required for HD-PTP and ESCRT-0 interdependent sorting of ubiquitinated transmembrane cargoes to ensure efficient receptor desensitization and lysosomal delivery.

B19-VLPs as an effective delivery system for tumour antigens to induce humoral and cellular immune responses against triple negative breast cancer

Cancer immunotherapy is emerging as a viable treatment option for several types of cancer. Active immunotherapy aims for the induction of specific antitumor immune responses; this goal requires strategies capable of increasing the immunogenicity of tumour antigens. Parvovirus B19 virus-like particles (B19-VLPs) formed of VP2 protein had been shown to be an effective multi-neoepitope delivery system capable of inducing specific cellular responses towards coupled antigens and reducing tumour growth and lung metastases in triple negative breast cancer mouse model. These findings encouraged us to further characterise these VP2 B19-VLPs by testing their capacity to simultaneously induce cellular and humoral responses towards other tumour-associated antigens, as this had not yet been evaluated. Here, we designed and evaluated in the 4T1 breast cancer model the prophylactic and therapeutic effect of VP2 B19-VLPs decorated with cellular (P53) and humoral (MUC1) epitopes. Balb/c mice were immunised with chimaeric VLPs, vehicle, or VLPs plus adjuvant. Tumour establishment and growth, lung metastasis, and cellular and humoral immune responses were evaluated. The prophylactic administration of chimaeric VLPs without adjuvant prevented the establishment of the tumour, while by therapeutic administration, chimaeric VLPs induced smaller tumour growth and decreased the number of metastases in the lung compared to wild-type VLPs. chimaeric VLPs induced high antibody titres towards the MUC1 epitope, as well as specific cellular responses towards P53 epitopes in lymph nodes local to the tumour. Our results reinforce and extend the utility of VP2 B19-VLPs as an encouraging tumour antigen delivery system in cancer immunotherapy able to improve tumour immunity in TNBC by inducing cellular and humoral immune responses.

CYRI-A limits invasive migration through macropinosome formation and integrin uptake regulation

The Scar/WAVE complex drives actin nucleation during cell migration. Interestingly, the same complex is important in forming membrane ruffles during macropinocytosis, a process mediating nutrient uptake and membrane receptor trafficking. Mammalian CYRI-B is a recently described negative regulator of the Scar/WAVE complex by RAC1 sequestration, but its other paralogue, CYRI-A, has not been characterized. Here, we implicate CYRI-A as a key regulator of macropinosome formation and integrin internalization. We find that CYRI-A is transiently recruited to nascent macropinosomes, dependent on PI3K and RAC1 activity. CYRI-A recruitment precedes RAB5A recruitment but follows sharply after RAC1 and actin signaling, consistent with it being a local inhibitor of actin polymerization. Depletion of both CYRI-A and -B results in enhanced surface expression of the α5β1 integrin via reduced internalization. CYRI depletion enhanced migration, invasion, and anchorage-independent growth in 3D. Thus, CYRI-A is a dynamic regulator of macropinocytosis, functioning together with CYRI-B to regulate integrin trafficking.

Bladder Cancer-related microRNAs With In Vivo Efficacy in Preclinical Models

Progressive and metastatic bladder cancer remain difficult to treat. In this review, we critique seven up-regulated and 25 down-regulated microRNAs in order to identify new therapeutic entities and corresponding targets. These microRNAs were selected with respect to their efficacy in bladder cancer-related preclinical in vivo models. MicroRNAs and related targets interfering with chemoresistance, cell-cycle, signaling, apoptosis, autophagy, transcription factor modulation, epigenetic modification and metabolism are described. In addition, we highlight microRNAs targeting transmembrane receptors and secreted factors. We discuss druggability issues for the identified targets.

The fibrillin-1 RGD motif posttranscriptionally regulates ERK1/2 signaling and fibroblast proliferation via miR-1208

Fibrillin-1 is an extracellular matrix protein which contains one conserved RGD integrin-binding motif. It constitutes the backbone of microfibrils in many tissues, and mutations in fibrillin-1 cause various connective tissue disorders. Although it is well established that fibrillin-1 interacts with several RGD-dependent integrins, very little is known about the associated intracellular signaling pathways. Recent published evidence identified a subset of miRNAs regulated by fibrillin-1 RGD-cell adhesion, with miR-1208 among the most downregulated. The present study shows that the downregulated miR-1208 controls fibroblast proliferation. Inhibitor experiments revealed that fibrillin-1 RGD suppressed miR-1208 expression via c-Src kinase and the downstream JNK signaling. Bioinformatic prediction and experimental target sequence validation demonstrated four miR-1208 binding sites on the ERK2 mRNA and one on the MEK1 mRNA. ERK2 and MEK1 are critical proliferation-promoting kinases. Decreased miR-1208 levels elevated the total and phosphorylated ERK1/2 and MEK1/2 protein levels and the phosphorylated to total ERK1/2 ratio. Together, the data demonstrate a novel outside-in signaling mechanism explaining how fibrillin-1 RGD-cell binding regulates fibroblast proliferation.

Probing mechanobiological role of filamin A in migration and invasion of human U87 glioblastoma cells using submicron soft pillars

Filamin A (FLNa) belongs to an actin-binding protein family in binding and cross-linking actin filaments into a three-dimensional structure. However, little attention has been given to its mechanobiological role in cancer cells. Here, we quantitatively investigated the role of FLNa by analyzing the following parameters in negative control (NC) and FLNa-knockdown (KD) U87 glioma cells using submicron pillars (900 nm diameter and 2 μm height): traction force (TF), rigidity sensing ability, cell aspect ratio, migration speed, and invasiveness. During the initial phase of cell adhesion (< 1 h), FLNa-KD cells polarized more slowly than did NC cells, which can be explained by the loss of rigidity sensing in FLNa-KD cells. The higher motility of FLNa-KD cells relative to NC cells can be explained by the high TF exerted by FLNa-KD cells when compared to NC cells, while the higher invasiveness of FLNa-KD cells relative to NC cells can be explained by a greater number of filopodia in FLNa-KD cells than in NC cells. Our results suggest that FLNa plays important roles in suppressing motility and invasiveness of U87 cells.

Effect arylamine N-acetyltransferase 1 on morphology, adhesion, migration, and invasion of MDA-MB-231 cells: role of matrix metalloproteinases and integrin αV

Reducted arylamine N-acetyltransferase (NAT1) in breast cancers is associated with poor patient survival. NAT1 has also been associated with changes in cancer cell survival and invasion both invitro and invivo. Here, we report the effects of NAT1 in cancer cell invasion by addressing its role in adherence, migration, and invasion in vitro. The NAT1 gene was deleted in MDA-MB-231, HT-29 and HeLa cells using CRISPR/Cas9 gene editing. Loss of NAT1 increased adherence to collagen in all three cell-lines but migration was unaffected. NAT1 deletion decreased invasion and induced changes to cell morphology. These effects were independent of matrix metalloproteinases but were related to integrin ITGαV expression. The data suggest NAT1 is important in adhesion and invasion through integrin expression.

Cell mechanical properties of human breast carcinoma cells depend on temperature

The knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in cancer therapy. Cell mechanical properties depend on a variety of factors, such as cellular environments, and may also rely on external factors, such as the ambient temperature. The impact of temperature on cell mechanics is not clearly understood. To explore the effect of temperature on cell mechanics, we employed magnetic tweezers to apply a force of 1 nN to 4.5 µm superparamagnetic beads. The beads were coated with fibronectin and coupled to human epithelial breast cancer cells, in particular MCF-7 and MDA-MB-231 cells. Cells were measured in a temperature range between 25 and 45 °C. The creep response of both cell types followed a weak power law. At all temperatures, the MDA-MB-231 cells were pronouncedly softer compared to the MCF-7 cells, whereas their fluidity was increased. However, with increasing temperature, the cells became significantly softer and more fluid. Since mechanical properties are manifested in the cell's cytoskeletal structure and the paramagnetic beads are coupled through cell surface receptors linked to cytoskeletal structures, such as actin and myosin filaments as well as microtubules, the cells were probed with pharmacological drugs impacting the actin filament polymerization, such as Latrunculin A, the myosin filaments, such as Blebbistatin, and the microtubules, such as Demecolcine, during the magnetic tweezer measurements in the specific temperature range. Irrespective of pharmacological interventions, the creep response of cells followed a weak power law at all temperatures. Inhibition of the actin polymerization resulted in increased softness in both cell types and decreased fluidity exclusively in MDA-MB-231 cells. Blebbistatin had an effect on the compliance of MDA-MB-231 cells at lower temperatures, which was minor on the compliance MCF-7 cells. Microtubule inhibition affected the fluidity of MCF-7 cells but did not have a significant effect on the compliance of MCF-7 and MDA-MB-231 cells. In summary, with increasing temperature, the cells became significant softer with specific differences between the investigated drugs and cell lines.

Induction of dormancy by confinement: An agarose-silica biomaterial for isolating and analyzing dormant cancer cells

The principal cause of cancer deaths is the residual disease, which eventually results in metastases. Certain metastases are induced by disseminated dormancy-capable single cancer cells that can reside within the body undetected for months to years. Awakening of the dormant cells starts a cascade resulting in the patient's demise. Despite its established clinical significance, dormancy research and its clinical translation have been hindered by lack of in vitro models that can identify, isolate, and analyze dormancy-capable cells. We have previously shown that immobilization of cells in a stiff microenvironment induces dormancy in dormancy-capable cell lines. In this communication, we present a novel biomaterial and an in vitro immobilization method to isolate, analyze, and efficiently recover dormancy-capable cancer cells. MCF-7, MDA-MB-231, and MDA-MB-468 cells were individually coated with agarose using a microfluidic flow-focusing device. Coated cells were then immobilized in a rigid and porous silica gel. Dormancy induction by this process was validated by decreased Ki-67 expression, increased p38/ERK activity ratio, and reduced expression of CDK-2, cyclins D1, and E1. We showed that we can reliably and repeatedly induce dormancy in dormancy-capable MCF-7 cells and enhance the dormancy-capable sub-population in MDA-MB-231 cells. As expected, dormancy-resistant MDA-MB-468 cells did not survive immobilization. The dormant cells could be awakened on demand, by digesting the agarose gel in situ, and efficiently recovered by magnetically separating the silica gel, making the cells available for downstream analysis and testing. The awakened cells were shown to regain motility immediately, proliferating, and migrating normally.