Focal adhesion kinase: the first ten years

Electroporation-derived melanoma extracellular particles activate fibroblasts

Although the pulse electric field (PEF) has been used in electrochemotherapy (ECT) for many years, the kinetics and profile of extracellular particles (EPs) released as a result of reversible electroporation have yet to be studied. It also needs to be clarified whether and how the profile of released EPs depends on the parameters of the applied PEF. The presented studies investigated the effect of EPs released from human melanoma cells after various parameters of reversible electroporation on markers indicating EP-mediated transformation of normal fibroblasts into tumor-associated fibroblasts. The expression levels of the vascular cell adhesion molecule-1 (VCAM-1) and changes in the expression of phosphor-histone H3 (pHH3), a biomarker specific for cells in mitosis, cell viability, and the migration capacity of the studied fibroblast cells, were analyzed. EPs were isolated from two commercial malignant melanoma cell lines previously subjected to reversible electroporation. Human primary fibroblasts (HPFs) were selected for EPs exposure. It was observed that after incubation with melanoma-derived EPs, HPFs showed differences in cell viability, migration capacity, VCAM-1, pHH3, and N-cadherin expression, depending on PEF parameters and the grade of melanoma cells. This study highlights that small extracellular particles (sEPs) from cancer cells can promote metastasis by carrying specific signals that lead to the upregulation of molecules like FAK, MMP-9, and N-cadherin in recipient cells.

Inhibition of hERG by ESEE suppresses the progression of colorectal cancer

Colorectal cancer (CRC) is one of the most common malignant cancers. Emodin is a lipophilic anthraquinone commonly found in medicinal herbs and known for its antitumor properties. However, its clinical utility has been hampered by low druggability. We designed and synthesized a new compound named Emodin succinimidyl ethyl ester (ESEE), which improves the bioavailability and preserves the original pharmacological effects of Emodin. In vitro, we have confirmed that ESEE induces apoptosis in colon cancer cells, suppresses cell proliferation, migration, and invasion, and inhibits the growth of subcutaneous transplantation tumors associated with colon cancer. And, in vivo, ESEE robustly inhibited tumor growth. Human Ether-a-go-go Related Gene (hERG) is aberrantly expressed in various cancer cells, where they play an important role in cancer progression. Focal adhesion kinase (FAK) is a tyrosine kinase overexpressed in cancer cells and plays an important role in the progression of tumors to a malignant phenotype. Mechanistically, the anti-CRC properties of ESEE are exerted through direct binding with hERG, which impedes the FAK/PI3K/AKT signaling axis-dependent apoptotic cascade.

Pyroligneous extract, a biomaterial derived from pyrolytic palm kernel shell wood vinegar, as a novel diabetic wound healing aid: an animal study

OBJECTIVE

Wound in diabetes is difficult to heal since it possesses excessive inflammation. The aim of the study was to evaluate wound healing activity of chitosan-based hydrogel containing pyroligneous acid in diabetic animals.

SIGNIFICANCE

Pyroligneous acid, a byproduct of biochar production from palm kernel shell biomass, contained oxygenated compounds which, with extracting enrichment, could promote wound healing.

METHODS

Streptozotocin-induced diabetic male jcl: ICR mice were subjected to create wounds and treat with hydrogel containing pyroligneous extract at dose strengths of 0 (placebo), 100 and 150 µg/g-gel. Commercial gel (Intrasite®) was used as an active comparator. On 3-, 7-, 10- and 14-day post-wounding, wound contraction was rated and wound site tissues were collected. The specimens were H&E stained and microscopically examined to evaluate histological responses. The underline wound healing related cytokine and polypeptide expressions were determined using real-time PCR and western blot.

RESULTS

It was found that the extract accelerated the healing process in a dose-dependent manner where at dose strength of 150 µg/g-gel was as effective as active comparator. It increased gene expression of the cytokine and related proteins in TGF-β/SMAD signaling pathway and may further activate diabetic induced TGF-β downregulation to restore up to the level that healthy skin tissues express. It also enhanced the expressions of Akt, FAK, RhoA and Rac-1 and evidently activated phosphorylation of Akt and FAK.

CONCLUSION

The study demonstrated the extract could be a novel biomaterial for healing of such a chronic inflammatory wound as the wound in diabetes.

A novel role of IGFBP5 in the migration, invasion and spheroids formation induced by IGF-I and insulin in MCF-7 breast cancer cells

PURPOSE

The insulin-like growth factor (IGF) system includes IGF-I, IGF-II insulin and their membrane receptors. IGF system also includes a family of proteins namely insulin-like growth factor-binding proteins (IGFBPs) composed for six major members (IGFBP-1 to IGFBP6), which capture, transport and prolonging half-life of IGFs. However, it has been described that IGFBPs can also have other functions.

METHODS

IGFBP5 expression was inhibited by shRNAs, migration was analyzed by scratch-wound assays, invasion assays were performed by the Boyden chamber method, spheroids formation assays were performed on ultra-low attachment surfaces, expression and phosphorylation of proteins were analyzed by Western blot.

RESULTS

IGFBP5 is a repressor of IGF-IR expression, but it is not a repressor of IR in MCF-7 breast cancer cells. In addition, IGFBP5 is a suppressor of migration and MMP-9 secretion induced by IGF-I and insulin, but it does not regulate invasion in MCF-7 cells. IGFBP5 also is a repressor of MCF-7 spheroids formation. However treatment with 340 nM rescues the inhibitory effect of IGFBP in the MCF-7 spheroids formation.

CONCLUSION

IGFBP5 regulates IGF-IR expression, migration and MMP-9 secretion induced by IGF-I and/or insulin, and the spheroids formation in MCF-7 breast cancer cells.

Exercise-specific adaptations in human skeletal muscle: Molecular mechanisms of making muscles fit and mighty

The mechanisms leading to a predominantly hypertrophied phenotype versus a predominantly oxidative phenotype, the hallmarks of resistance training (RT) or aerobic training (AT), respectively, are being unraveled. In humans, exposure of naïve persons to either AT or RT results in their skeletal muscle exhibiting generic 'exercise stress-related' signaling, transcription, and translation responses. However, with increasing engagement in AT or RT, the responses become refined, and the phenotype typically associated with each form of exercise emerges. Here, we review some of the mechanisms underpinning the adaptations of how muscles become, through AT, 'fit' and RT, 'mighty.' Much of our understanding of molecular exercise physiology has arisen from targeted analysis of post-translational modifications and measures of protein synthesis. Phosphorylation of specific residue sites has been a dominant focus, with canonical signaling pathways (AMPK and mTOR) studied extensively in the context of AT and RT, respectively. These alone, along with protein synthesis, have only begun to elucidate key differences in AT and RT signaling. Still, key yet uncharacterized differences exist in signaling and regulation of protein synthesis that drive unique adaptation to AT and RT. Omic studies are required to better understand the divergent relationship between exercise and phenotypic outcomes of training.

Focal adhesion kinase regulates tendon cell mechanoresponse and physiological tendon development

Tendons enable locomotion by transmitting high tensile mechanical forces between muscle and bone via their dense extracellular matrix (ECM). The application of extrinsic mechanical stimuli via muscle contraction is necessary to regulate healthy tendon function. Specifically, applied physiological levels of mechanical loading elicit an anabolic tendon cell response, while decreased mechanical loading evokes a degradative tendon state. Although the tendon response to mechanical stimuli has implications in disease pathogenesis and clinical treatment strategies, the cell signaling mechanisms by which tendon cells sense and respond to mechanical stimuli within the native tendon ECM remain largely unknown. Therefore, we explored the role of cell-ECM adhesions in regulating tendon cell mechanotransduction by perturbing the genetic expression and signaling activity of focal adhesion kinase (FAK) through both in vitro and in vivo approaches. We determined that FAK regulates tendon cell spreading behavior and focal adhesion morphology, nuclear deformation in response to applied mechanical strain, and mechanosensitive gene expression. In addition, our data reveal that FAK signaling plays an essential role in in vivo tendon development and postnatal growth, as FAK-knockout mouse tendons demonstrated reduced tendon size, altered mechanical properties, differences in cellular composition, and reduced maturity of the deposited ECM. These data provide a foundational understanding of the role of FAK signaling as a critical regulator of in situ tendon cell mechanotransduction. Importantly, an increased understanding of tendon cell mechanotransductive mechanisms may inform clinical practice as well as lead to the discovery of diagnostic and/or therapeutic molecular targets.

FAK Family Kinases: A Potential Therapeutic Target for Atherosclerosis

Atherosclerosis (AS) is a chronic progressive inflammatory disease of the vascular wall and the primary pathological basis of cardiovascular and cerebrovascular disease. Focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (Pyk2), two highly homologous members of the FAK family kinases, play critical roles in integrin signaling. They also serve as scaffolding proteins that contribute to the assembly of cellular signaling complexes that regulate cell survival, cell cycle progression, and cell motility. Research indicates that the FAK family kinases is involved in the gene regulation of vascular cells and that aberrant expression of this family is associated with pathological changes in vascular disease. These findings establish the FAK family kinases as a critical signaling mediator in atherosclerotic lesions and inhibition of its activity has the potential to attenuate the pathological progression of AS. This review highlights the indispensable role of the FAK family kinases in abnormal vascular smooth muscle cell proliferation, endothelial cell dysfunction, inflammation, and lipid metabolism associated with AS. We also summarize therapeutic targets against the FAK family kinases, providing valuable insights into therapeutic strategies for AS.

Sustained intestinal epithelial monolayer wound closure after transient application of a FAK-activating small molecule

M64HCl, which has drug-like properties, is a water-soluble Focal Adhesion Kinase (FAK) activator that promotes murine mucosal healing after ischemic or NSAID-induced injury. Since M64HCl has a short plasma half-life in vivo (less than two hours), it has been administered as a continuous infusion with osmotic minipumps in previous animal studies. However, the effects of more transient exposure to M64HCl on monolayer wound closure remained unclear. Herein, we compared the effects of shorter M64HCl treatment in vitro to continuous treatment for 24 hours on monolayer wound closure. We then investigated how long FAK activation and downstream ERK1/2 activation persist after two hours of M64HCl treatment in Caco-2 cells. M64HCl concentrations immediately after washing measured by mass spectrometry confirmed that M64HCl had been completely removed from the medium while intracellular concentrations had been reduced by 95%. Three-hour and four-hour M64HCl (100 nM) treatment promoted epithelial sheet migration over 24 hours similar to continuous 24-hour exposure. 100nM M64HCl did not increase cell number. Exposing cells twice with 2-hr exposures of M64HCl during a 24-hour period had a similar effect. Both FAK inhibitor PF-573228 (10 μM) and ERK kinase (MEK) inhibitor PD98059 (20 μM) reduced basal wound closure in the absence of M64HCl, and each completely prevented any stimulation of wound closure by M64HCl. Rho kinase inhibitor Y-27632 (20 μM) stimulated Caco-2 monolayer wound closure but no further increase was seen with M64HCl in the presence of Y-27632. M64HCl (100 nM) treatment for 3 hours stimulated Rho kinase activity. M64HCl decreased F-actin in Caco-2 cells. Furthermore, a two-hour treatment with M64HCl (100 nM) stimulated sustained FAK activation and ERK1/2 activation for up to 16 and hours 24 hours, respectively. These results suggest that transient M64HCl treatment promotes prolonged intestinal epithelial monolayer wound closure by stimulating sustained activation of the FAK/ERK1/2 pathway. Such molecules may be useful to promote gastrointestinal mucosal repair even with a relatively short half-life.

Acidic preconditioning induced intracellular acid adaptation to protect renal injury via dynamic phosphorylation of focal adhesion kinase-dependent activation of sodium hydrogen exchanger 1

BACKGROUND

Disruptions in intracellular pH (pHi) homeostasis, causing deviations from the physiological range, can damage renal epithelial cells. However, the existence of an adaptive mechanism to restore pHi to normalcy remains unclear. Early research identified H+ as a critical mediator of ischemic preconditioning (IPC), leading to the concept of acidic preconditioning (AP). This concept proposes that short-term, repetitive acidic stimulation can enhance a cell's capacity to withstand subsequent adverse stress. While AP has demonstrated protective effects in various ischemia-reperfusion (I/R) injury models, its application in kidney injury remains largely unexplored.

METHODS

An AP model was established in human kidney (HK2) cells by treating them with an acidic medium for 12 h, followed by a recovery period with a normal medium for 6 h. To induce hypoxia/reoxygenation (H/R) injury, HK2 cells were subjected to hypoxia for 24 h and reoxygenation for 1 h. In vivo, a mouse model of IPC was established by clamping the bilateral renal pedicles for 15 min, followed by reperfusion for 4 days. Conversely, the I/R model involved clamping the bilateral renal pedicles for 35 min and reperfusion for 24 h. Western blotting was employed to evaluate the expression levels of cleaved caspase 3, cleaved caspase 9, NHE1, KIM1, FAK, and NOX4. A pH-sensitive fluorescent probe was used to measure pHi, while a Hemin/CNF microelectrode monitored kidney tissue pH. Immunofluorescence staining was performed to visualize the localization of NHE1, NOX4, and FAK, along with the actin cytoskeleton structure in HK2 cells. Cell adhesion and scratch assays were conducted to assess cell motility.

RESULTS

Our findings demonstrated that AP could effectively mitigate H/R injury in HK2 cells. This protective effect and the maintenance of pHi homeostasis by AP involved the upregulation of Na+/H+ exchanger 1 (NHE1) expression and activity. The activity of NHE1 was regulated by dynamic changes in pHi-dependent phosphorylation of Focal Adhesion Kinase (FAK) at Y397. This process was associated with NOX4-mediated reactive oxygen species (ROS) production. Furthermore, AP induced the co-localization of FAK, NOX4, and NHE1 in focal adhesions, promoting cytoskeletal remodeling and enhancing cell adhesion and migration capabilities.

CONCLUSIONS

This study provides compelling evidence that AP maintains pHi homeostasis and promotes cytoskeletal remodeling through FAK/NOX4/NHE1 signaling. This signaling pathway ultimately contributes to alleviated H/R injury in HK2 cells.

Focal adhesion kinase signaling - tumor vulnerabilities and clinical opportunities

Focal adhesion kinase (FAK; encoded by PTK2) was discovered over 30 years ago as a cytoplasmic protein tyrosine kinase that is localized to cell adhesion sites, where it is activated by integrin receptor binding to extracellular matrix proteins. FAK is ubiquitously expressed and functions as a signaling scaffold for a variety of proteins at adhesions and in the cell cytoplasm, and with transcription factors in the nucleus. FAK expression and intrinsic activity are essential for mouse development, with molecular connections to cell motility, cell survival and gene expression. Notably, elevated FAK tyrosine phosphorylation is common in tumors, including pancreatic and ovarian cancers, where it is associated with decreased survival. Small molecule and orally available FAK inhibitors show on-target inhibition in tumor and stromal cells with effects on chemotherapy resistance, stromal fibrosis and tumor microenvironment immune function. Herein, we discuss recent insights regarding mechanisms of FAK activation and signaling, its roles as a cytoplasmic and nuclear scaffold, and the tumor-intrinsic and -extrinsic effects of FAK inhibitors. We also discuss results from ongoing and advanced clinical trials targeting FAK in low- and high-grade serous ovarian cancers, where FAK acts as a master regulator of drug resistance. Although FAK is not known to be mutationally activated, preventing FAK activity has revealed multiple tumor vulnerabilities that support expanding clinical combinatorial targeting possibilities.

Kaempferol-Enhanced Migration and Differentiation of C2C12 Myoblasts via ITG1B/FAK/Paxillin and IGF1R/AKT/mTOR Signaling Pathways

SCOPE

Kaempferol (KMP), a bioactive flavonoid compound found in fruits and vegetables, contributes to human health in many ways but little is known about its relationship with muscle mass. The effect of KMP on C2C12 myoblast differentiation and the mechanisms that might underlie that effect are studied.

METHODS AND RESULTS

This study finds that KMP (1, 10 µM) increases the migration and differentiation of C2C12 myoblasts in vitro. Studying the possible mechanism underlying its effect on migration, the study finds that KMP activates Integrin Subunit Beta 1 (ITGB1) in C2C12 myoblasts, increasing p-FAK (Tyr398) and its downstream cell division cycle 42 (CDC42), a protein previously associated with cell migration. Regarding differentiation, KMP upregulates the expression of myosin heavy chain (MHC) and activates IGF1/AKT/mTOR/P70S6K. Interestingly, pretreatment with an AKT inhibitor (LY294002) and siRNA knockdown of IGF1R leads to a decrease in cell differentiation, suggesting that IGF1/AKT activation is required for KMP to induce C2C12 myoblast differentiation.

CONCLUSION

Together, the findings suggest that KMP enhances the migration and differentiation of C2C12 myoblasts through the ITG1B/FAK/paxillin and IGF1R/AKT/mTOR pathways. Thus, KMP supplementation might potentially be used to prevent or delay age-related loss of muscle mass and help maintain muscle health.

FAK regulates tension transmission to the nucleus and endothelial transcriptome independent of kinase activity

The mechanical environment generated through the adhesive interaction of endothelial cells (ECs) with the matrix controls nuclear tension, preventing aberrant gene synthesis and the transition from restrictive to leaky endothelium, a hallmark of acute lung injury (ALI). However, the mechanisms controlling tension transmission to the nucleus and EC-restrictive fate remain elusive. Here, we demonstrate that, in a kinase-independent manner, focal adhesion kinase (FAK) safeguards tension transmission to the nucleus to maintain EC-restrictive fate. In FAK-depleted ECs, robust activation of the RhoA-Rho-kinase pathway increased EC tension and phosphorylation of the nuclear envelope protein, emerin, activating DNMT3a. Activated DNMT3a methylates the KLF2 promoter, impairing the synthesis of KLF2 and its target S1PR1 to induce the leaky EC transcriptome. Repleting FAK (wild type or kinase dead) or inhibiting RhoA-emerin-DNMT3a activities in damaged lung ECs restored KLF2 transcription of the restrictive EC transcriptome. Thus, FAK sensing and control of tension transmission to the nucleus govern restrictive endothelium to maintain lung homeostasis.

Metabolic disorders induced the changes in the expressions of TNFα, E-cadherin and ultrastructural alteration of liver cells in a typical animal model of type 2 diabetes: Psammomys obesus

By using a unique animal model of type 2 diabetes mellitus, Psammomys obesus induced by a high-calorie diet (HCD) for nine months, we showed for the first time, in the liver, the impact of inflammation on the remodeling of intercellular junction molecules E-cadherins during the progression of steatohepatitis. Under the effect of HCD, the expressions of immunohistochemical markers, Tumor Necrosis Factor alpha (TNFα) and E-cadherins were inversely correlated. Ultrastructural examination revealed the involvement of destabilization and loss of E-cadherins in the process of hepatic pathogenesis. This mechanical maintenance stress was favored by the recruitment of immune cells which contributed to the triggering and progression of fibrosis by the enlargement of the intercellular space and the invasion of collagen fibers. Furthermore to escape cell death, loss of E-cadherins played a major role in mediating fibrosis. Psammomys obesus is a promising model for experimental research, enabling the extrapolation of observed structural and functional alterations in humans, the objective to find new therapeutic targets. The physiological resemblance between Psammomys obesus and humans enhances the precision and relevance of biomedical research efforts.

The suppression of cell motility through the reduction of FAK activity and expression of cell adhesion proteins by hAMSCs secretome in MDA-MB-231 breast cancer cells

Breast cancer is a leading cause of death in women worldwide. Cancer therapy based on stem cells is considered as a novel and promising platform. In the present study, we explore the therapeutic effects of human amniotic mesenchymal stromal cells (hAMSCs) through the reduction of focal adhesion kinase (FAK) activity, SHP-2, and cell adhesion proteins such as Paxillin, Vinculin, Fibronectin, Talin, and integrin αvβ3 expression in MDA-MB-231 breast cancer cells. For this purpose, we employed a co-culture system using 6-well plate transwell. After 72 h, hAMSCs-treated MDA-MB-231 breast cancer cells, the activity of focal adhesion kinase (FAK) and the expression of SHP-2 and cell adhesion proteins such as Paxillin, Vinculin, Fibronectin, Talin, and integrin αvβ3 expression were analyzed using western blot. The shape and migration of cells were also analyzed. Based on our results, a significant reduction in tumor cell motility through downregulation of the tyrosine phosphorylation level of FAK (at Y397 and Y576/577 sites) and cell adhesion expression in MDA-MB-231 breast cancer cells was demonstrated. Our findings indicate that hAMSCS secretome has therapeutic effects on cancer cell migration through downregulation of FAK activity and expression of cell adhesion proteins.

Prospects of focal adhesion kinase inhibitors as a cancer therapy in preclinical and early phase study

INTRODUCTION

FAK, a nonreceptor cytoplasmic tyrosine kinase, plays a crucial role in tumor metastasis, drug resistance, tumor stem cell maintenance, and regulation of the tumor microenvironment. FAK has emerged as a promising target for tumor therapy based on both preclinical and clinical data.

AREAS COVERED

This paper aims to summarize the molecular mechanisms underlying FAK's involvement in tumorigenesis and progression. Encouraging results have emerged from ongoing clinical trials of FAK inhibitors. Additionally, we present an overview of clinical trials for FAK inhibitors, examining their potential as promising treatments. The pertinent studies gathered from databases including PubMed, ClinicalTrials.gov.

EXPERT OPINION

Since the first finding in 1990s, targeting FAK has became the focus of interests in many pharmaceutical companies. Through 30 years' discovery, the industry and academy gradually realized the features of FAK target which may not be a driver gene but a solid defense system for the cancer initiation and development. Currently, the ongoing clinical regimens involving FAK inhibition are all the combination strategies in which FAK inhibitors can further strengthen the cancer cell killing effects of other testing agents. The emerging positive signal in clinical trials foresee targeting FAK as class will be an effective mean to fight against cancers.

Construction of Vero cell-adapted rabies vaccine strain by five amino acid substitutions in HEP-Flury strain

Rabies virus (RABV) causes fatal neurological disease. Pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) using inactivated-virus vaccines are the most effective measures to prevent rabies. In Japan, HEP-Flury, the viral strain, used as a human rabies vaccine, has historically been propagated in primary fibroblast cells derived from chicken embryos. In the present study, to reduce the cost and labor of vaccine production, we sought to adapt the original HEP-Flury (HEP) to Vero cells. HEP was repeatedly passaged in Vero cells to generate ten- (HEP-10V) and thirty-passaged (HEP-30V) strains. Both HEP-10V and HEP-30V grew significantly better than HEP in Vero cells, with virulence and antigenicity similar to HEP. Comparison of the complete genomes with HEP revealed three non-synonymous mutations in HEP-10V and four additional non-synonymous mutations in HEP-30V. Comparison among 18 recombinant HEP strains constructed by reverse genetics and vesicular stomatitis viruses pseudotyped with RABV glycoproteins indicated that the substitution P(L115H) in the phosphoprotein and G(S15R) in the glycoprotein improved viral propagation in HEP-10V, while in HEP-30V, G(V164E), G(L183P), and G(A286V) in the glycoprotein enhanced entry into Vero cells. The obtained recombinant RABV strain, rHEP-PG4 strain, with these five substitutions, is a strong candidate for production of human rabies vaccine.

Blood-testis barrier: a review on regulators in maintaining cell junction integrity between Sertoli cells

The blood-testis barrier (BTB) is formed adjacent to the seminiferous basement membrane. It is a distinct ultrastructure, partitioning testicular seminiferous epithelium into apical (adluminal) and basal compartments. It plays a vital role in developing and maturing spermatocytes into spermatozoa via reorganizing its structure. This enables the transportation of preleptotene spermatocytes across the BTB, from basal to adluminal compartments in the seminiferous tubules. Several bioactive peptides and biomolecules secreted by testicular cells regulate the BTB function and support spermatogenesis. These peptides activate various downstream signaling proteins and can also be the target themself, which could improve the diffusion of drugs across the BTB. The gap junction (GJ) and its coexisting junctions at the BTB maintain the immunological barrier integrity and can be the "gateway" during spermatocyte transition. These junctions are the possible route for toxicant entry, causing male reproductive dysfunction. Herein, we summarize the detailed mechanism of all the regulators playing an essential role in the maintenance of the BTB, which will help researchers to understand and find targets for drug delivery inside the testis.

Global research trends and emerging opportunities for integrin adhesion complexes in cardiac repair: a scientometric analysis

Objective

Cardiac regenerative medicine has gained significant attention in recent years, and integrins are known to play a critical role in mediating cardiac development and repair, especially after an injury from the myocardial infarction (MI). Given the extensive research history and interdisciplinary nature of this field, a quantitative retrospective analysis and visualization of related topics is necessary.

Materials and methods

We performed a scientometric analysis of published papers on cardiac integrin adhesion complexes (IACs), including analysis of annual publications, disciplinary evolution, keyword co-occurrence, and literature co-citation.

Results

A total of 2,664 publications were finally included in the past 20 years. The United States is the largest contributor to the study and is leading this area of research globally. The journal Circulation Research attracts the largest number of high-quality publications. The study of IACs in cardiac repair/regenerative therapies involves multiple disciplines, particularly in materials science and developmental biology. Keywords of research frontiers were represented by Tenasin-C (2019-2023) and inflammation (2020-2023).

Conclusion

Integrins are topics with ongoing enthusiasm in biological development and tissue regeneration. The rapidly emerging role of matricellular proteins and non-protein components of the extracellular matrix (ECM) in regulating matrix structure and function may be a further breakthrough point in the future; the emerging role of IACs and their downstream molecular signaling in cardiac repair are also of great interest, such as induction of cardiac proliferation, differentiation, maturation, and metabolism, fibroblast activation, and inflammatory modulation.

Hepatic Sinusoid Capillarizate via IGTAV/FAK Pathway Under High Glucose

The incidence of diabetic patients with non-alcoholic fatty liver disease (NAFLD) is continuously increasing worldwide. However, the specific mechanisms of NAFLD patients with diabetes are still not clear. Recent studies have indicated that integrins play an important role in NAFLD. In this study, we considered the relationship between integrin αv (IGTAV)/FAK pathway and sinusoidal capillarization. We investigated the difference between the expression of IGTAV, laminin (LN), focal adhesion kinase (FAK), and phosphor-FAK protein in human liver sinusoidal endothelial cells (HLSECs) to explore the specific mechanisms of the diseases of NAFLD with diabetes under high glucose. We cultured and identified the HLSECs and constructed the recombinant lentivirus vector with IGTAV shRNA by quantitative real-time PCR (qRT-PCR) to silence the IGTAV gene. Cells were divided into groups of 25 mmol/L glucose and 25 mmol/L mannitol. We measured the protein levels of IGTAV, LN, FAK, and phosphor-FAK by western blot at 2 h, 6 h, and 12 h before and after IGTAV gene silencing. The lentivirus vector was successfully constructed with IGTAV shRNA. The HLSECs under high glucose were observed by scanning electron microscope. SPSS19.0 was used for statistical analysis. High glucose significantly increased the expression of IGTAV, LN, and phosphor-FAK protein in HLSECs; the shRNA IGTAV could effectively inhibit the expression of phosphor-FAK and LN at 2 h and 6 h. Inhibition of the phosphor-FAK could effectively decrease the expression of LN in HLSECs at 2 h and 6 h under high glucose. Inhibition of IGTAV gene of HLSECs under high glucose could improve hepatic sinus capillarization. Inhibition of IGTAV and phosphor-FAK decreased the expression of LN. High glucose led to hepatic sinus capillarization via IGTAV/ FAK pathway.

Extracellular matrix biomechanical roles and adaptation in health and disease

Extracellular matrices (ECMs) are dynamic 3D macromolecular networks that exhibit structural characteristics and composition specific to different tissues, serving various biomechanical and regulatory functions. The interactions between ECM macromolecules such as collagen, elastin, glycosaminoglycans (GAGs), proteoglycans (PGs), fibronectin, and laminin, along with matrix effectors and water, contribute to the unique cellular and tissue functional properties during organ development, tissue homoeostasis, remodeling, disease development, and progression. Cells adapt to environmental changes by adjusting the composition and array of ECM components. ECMs, forming the 3D bioscaffolds of our body, provide mechanical support for tissues and organs and respond to the environmental variables influencing growth and final adult body shape in mammals. Different cell types display distinct adaptations to the respective ECM environments. ECMs regulate biological processes by controlling the diffusion of infections and inflammations, sensing and adapting to external stimuli and gravity from the surrounding habitat, and, in the context of cancer, interplaying with and regulating cancer cell invasion and drug resistance. Alterations in the ECM composition in pathological conditions drive adaptive responses of cells and could therefore result in abnormal cell behavior and tissue dysfunction. Understanding the biomechanical functionality, adaptation, and roles of distinct ECMs is essential for research on various pathologies, including cancer progression and multidrug resistance, which is of crucial importance for developing targeted therapies. In this Viewpoint article, we critically present and discuss specific biomechanical functions of ECMs and regulatory adaptation mechanisms in both health and disease, with a particular focus on cancer progression.

Durotaxis and negative durotaxis: where should cells go?

Durotaxis and negative durotaxis are processes in which cell migration is directed by extracellular stiffness. Durotaxis is the tendency of cells to migrate toward stiffer areas, while negative durotaxis occurs when cells migrate toward regions with lower stiffness. The mechanisms of both processes are not yet fully understood. Additionally, the connection between durotaxis and negative durotaxis remains unclear. In this review, we compare the mechanisms underlying durotaxis and negative durotaxis, summarize the basic principles of both, discuss the possible reasons why some cell types exhibit durotaxis while others exhibit negative durotaxis, propose mechanisms of switching between these processes, and emphasize the challenges in the investigation of durotaxis and negative durotaxis.

HSP47 levels determine the degree of body adiposity

Adiposity varies among individuals with the influence of diverse physiological, pathological, environmental, hormonal, and genetic factors, but a unified molecular basis remains elusive. Here, we identify HSP47, a collagen-specific chaperone, as a key determinant of body adiposity. HSP47 expression is abundant in adipose tissue; increased with feeding, overeating, and obesity; decreased with fasting, exercise, calorie restriction, bariatric surgery, and cachexia; and correlated with fat mass, BMI, waist, and hip circumferences. Insulin and glucocorticoids, respectively, up- and down-regulate HSP47 expression. In humans, the increase of HSP47 gene expression by its intron or synonymous variants is associated with higher body adiposity traits. In mice, the adipose-specific knockout or pharmacological inhibition of HSP47 leads to lower body adiposity compared to the control. Mechanistically, HSP47 promotes collagen dynamics in the folding, secretion, and interaction with integrin, which activates FAK signaling and preserves PPARγ protein from proteasomal degradation, partly related to MDM2. The study highlights the significance of HSP47 in determining the amount of body fat individually and under various circumstances.

Human amniotic membrane inhibits migration and invasion of muscle-invasive bladder cancer urothelial cells by downregulating the FAK/PI3K/Akt/mTOR signalling pathway

Bladder cancer is the 10th most commonly diagnosed cancer with the highest lifetime treatment costs. The human amniotic membrane (hAM) is the innermost foetal membrane that possesses a wide range of biological properties, including anti-inflammatory, antimicrobial and anticancer properties. Despite the growing number of studies, the mechanisms associated with the anticancer effects of human amniotic membrane (hAM) are poorly understood. Here, we reported that hAM preparations (homogenate and extract) inhibited the expression of the epithelial-mesenchymal transition markers N-cadherin and MMP-2 in bladder cancer urothelial cells in a dose-dependent manner, while increasing the secretion of TIMP-2. Moreover, hAM homogenate exerted its antimigratory effect by downregulating the expression of FAK and proteins involved in actin cytoskeleton reorganisation, such as cortactin and small RhoGTPases. In muscle-invasive cancer urothelial cells, hAM homogenate downregulated the PI3K/Akt/mTOR signalling pathway, the key cascade involved in promoting bladder cancer. By using normal, non-invasive papilloma and muscle-invasive cancer urothelial models, new perspectives on the anticancer effects of hAM have emerged. The results identify new sites for therapeutic intervention and are prompt encouragement for ongoing anticancer drug development studies.

Yersinia deploys type III-secreted effectors to evade caspase-4 inflammasome activation in human cells

IMPORTANCE

Yersinia are responsible for significant disease burden in humans, ranging from recurrent disease outbreaks (yersiniosis) to pandemics (Yersinia pestis plague). Together with rising antibiotic resistance rates, there is a critical need to better understand Yersinia pathogenesis and host immune mechanisms, as this information will aid in developing improved immunomodulatory therapeutics. Inflammasome responses in human cells are less studied relative to murine models of infection, though recent studies have uncovered key differences in inflammasome responses between mice and humans. Here, we dissect human intestinal epithelial cell and macrophage inflammasome responses to Yersinia pseudotuberculosis. Our findings provide insight into species- and cell type-specific differences in inflammasome responses to Yersinia.

Unusual effects of a nanoporous gold substrate on cell adhesion and differentiation because of independent multi-branch signaling of focal adhesions

A variety of cell behaviors, such as cell adhesion, motility, and fate, can be controlled by substrate characteristics such as surface topology and chemistry. In particular, the surface topology of substrates strongly affects cell behaviors, and the topological spacing is a critical factor in inducing cell responses. Various works have demonstrated that cell adhesion was enhanced with decreasing topological spacing although differentiation progressed slowly. However, there are exceptions, and thus, correlations between topological spacing and cell responses are still debated. We show that a nanoporous gold substrate affected cell adhesion while it neither affected osteogenic nor adipogenic differentiation. In addition, the cell adhesion was reduced with decreasing pore size. These do not agree with previous findings. A focal adhesion (FA) is an aggregate of modules comprising specific proteins such as FA kinase, talin, and vinculin. Therefore, it is suggested that because various extracellular signals can be independently branched off from the FA modules, the unusual effects of nanoporous gold substrates are related to the multi-branching of FAs.

Hyaluronic acid: More than a carrier, having an overpowering extracellular and intracellular impact on cancer

Hyaluronic acid (HA), also named hyaluronan, is an omnipresent component of the tissue microenvironment. It is extensively used to formulate targeted drug delivery systems for cancer. Although HA itself has pivotal influences in various cancers, its calibers are somewhat neglected when using it as delivering platform to treat cancer. In the last decade, multiple studies revealed roles of HA in cancer cell proliferation, invasion, apoptosis, and dormancy through pathways like mitogen-activated protein kinase-extracellular signal-regulated kinase (MAPK/ERK), P³⁸, and nuclear factor kappa-light chain-enhancer of activated B cells (NFκB). A more fascinating fact is that the distinct molecular weight (MW) of HA exerts disparate effects on the same type of cancer. Its overwhelming use in cancer therapy and other therapeutic products make collective research on the sundry impact of it on various types of cancer, an essential aspect to be considered in all of these domains. Even the development of new therapies against cancer needed meticulous studies on HA because of its divergence of activity based on MW. This review will provide painstaking insight into the extracellular and intracellular bioactivity of HA, its modified forms, and its MW in cancers, which may improve the management of cancer.

Mechanisms of mechanical overload-induced skeletal muscle hypertrophy: current understanding and future directions

Mechanisms underlying mechanical overload-induced skeletal muscle hypertrophy have been extensively researched since the landmark report by Morpurgo (1897) of "work-induced hypertrophy" in dogs that were treadmill trained. Much of the preclinical rodent and human resistance training research to date supports that involved mechanisms include enhanced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, an expansion in translational capacity through ribosome biogenesis, increased satellite cell abundance and myonuclear accretion, and postexercise elevations in muscle protein synthesis rates. However, several lines of past and emerging evidence suggest that additional mechanisms that feed into or are independent of these processes are also involved. This review first provides a historical account of how mechanistic research into skeletal muscle hypertrophy has progressed. A comprehensive list of mechanisms associated with skeletal muscle hypertrophy is then outlined, and areas of disagreement involving these mechanisms are presented. Finally, future research directions involving many of the discussed mechanisms are proposed.

Prolonged mechanical muscle loading increases mechanosensor gene and protein levels and causes a moderate fast-to-slow fiber type switch in mice

Mechanosensing and subsequent mechanotransduction are indispensable for muscle plasticity. Nevertheless, a scarcity of literature exists regarding an all-encompassing understanding of the muscle mechanosensing machinery's response to prolonged loading, especially in conditions that resemble a natural physiological state of skeletal muscle. This study aimed to comprehensively explore the effects of prolonged mechanical loading on mechanosensitive components, skeletal muscle characteristics, and metabolism-related gene clusters. Twenty male C57BL/6J mice were randomly divided into two groups: control and prolonged mechanical loading. To induce prolonged mechanical loading on the triceps brachii (TRI) and biceps brachii (BIC) muscles, a 14-day period of tail suspension was implemented. In TRI only, prolonged mechanical loading caused a mild fast-to-slow fiber type shift together with increased mechanosensor gene and protein levels. It also increased transcription factors associated with slow muscle fibers while decreasing those related to fast-type muscle gene expression. Succinate dehydrogenase activity, a marker of muscle oxidative capacity, and genes involved in oxidative and mitochondrial turnover increased, whereas glycolytic-related genes decreased. Moreover, prolonged mechanical loading stimulated markers of muscle protein synthesis. Taken together, our data show a collective muscle-specific increase in mechanosensor gene and protein levels upon a period of prolonged mechanical loading in conditions that reflect a more natural physiological state of skeletal muscle in mice. We provide additional proof-of-concept that prolonged tail suspension-induced loading of the forelimbs triggers a muscle-specific fast-to-slow fiber type switch, and this coincides with increased protein synthesis-related signaling.NEW & NOTEWORTHY This study provides a comprehensive overview of the effects of prolonged loading on mechanosensitive components in conditions that better reflect the natural physiological state of skeletal muscle. Although the muscle mechanosensing machinery has been widely acknowledged for its responsiveness to altered loading, an inclusive understanding of its response to prolonged loading remains scarce. Our results show a fast-to-slow fiber type shift and an upregulation of mechanosensor gene and protein levels following prolonged loading.

Focal adhesion kinase: from biological functions to therapeutic strategies

Focal adhesion kinase (FAK), a nonreceptor cytoplasmic tyrosine kinase, is a vital participant in primary cellular functions, such as proliferation, survival, migration, and invasion. In addition, FAK regulates cancer stem cell activities and contributes to the formation of the tumor microenvironment (TME). Importantly, increased FAK expression and activity are strongly associated with unfavorable clinical outcomes and metastatic characteristics in numerous tumors. In vitro and in vivo studies have demonstrated that modulating FAK activity by application of FAK inhibitors alone or in combination treatment regimens could be effective for cancer therapy. Based on these findings, several agents targeting FAK have been exploited in diverse preclinical tumor models. This article briefly describes the structure and function of FAK, as well as research progress on FAK inhibitors in combination therapies. We also discuss the challenges and future directions regarding anti-FAK combination therapies.

Off-target pharmacological activity at various kinases: Potential functional and pathological side effects

In drug discovery, during the lead optimization and candidate characterization stages, novel small molecules are frequently evaluated in a battery of in vitro pharmacology assays to identify potential unintended, off-target interactions with various receptors, transporters, ion channels, and enzymes, including kinases. Furthermore, these screening panels may also provide utility at later stages of development to provide a mechanistic understanding of unexpected safety findings. Here, we present a compendium of the most likely functional and pathological outcomes associated with interaction(s) to a panel of 95 kinases based on an extensive curation of the scientific literature. This panel of kinases was designed by AbbVie based on safety-related data extracted from the literature, as well as from over 20 years of institutional knowledge generated from discovery efforts. For each kinase, the scientific literature was reviewed using online databases and the most often reported functional and pathological effects were summarized. This work should serve as a practical guide for small molecule drug discovery scientists and clinical investigators to predict and/or interpret adverse effects related to pharmacological interactions with these kinases.

Proteomic and Phosphoproteomic Analysis Reveals Differential Immune Response to Hirame Novirhabdovirus (HIRRV) Infection in the Flounder (Paralichthys olivaceus) under Different Temperature

Hirame novirhabdovirus (HIRRV) is one of most serious viral pathogens causing significant economic losses to the flounder (Paralichthys olivaceus)-farming industry. Previous studies have shown that the outbreak of HIRRV is highly temperature-dependent, and revealed the viral replication was significantly affected by the antiviral response of flounders under different temperatures. In the present study, the proteome and phosphoproteome was used to analyze the different antiviral responses in the HIRRV-infected flounder under 10 °C and 20 °C. Post viral infection, 472 differentially expressed proteins (DEPs) were identified in the spleen of flounder under 10 °C, which related to NOD-like receptor signaling pathway, RIG-I-like receptor signaling pathway, RNA transport and so on. Under 20 °C, 652 DEPs were identified and involved in focal adhesion, regulation of actin cytoskeleton, phagosome, NOD-like receptor signaling pathway and RIG-I-like receptor signaling pathway. Phosphoproteome analysis showed that 675 differentially expressed phosphoproteins (DEPPs) were identified in the viral infected spleen under 10 °C and significantly enriched in Spliceosome, signaling pathway, necroptosis and RNA transport. Under 20 °C, 1304 DEPPs were identified and significantly enriched to Proteasome, VEGF signaling pathway, apoptosis, Spliceosome, mTOR signaling pathway, mRNA surveillance pathway, and RNA transport. To be noted, the proteins and phosphoproteins involved in interferon production and signaling showed significant upregulations in the viral infected flounder under 20 °C compared with that under 10 °C. Furthermore, the temporal expression profiles of eight selected antiviral-related mRNA including IRF3, IRF7, IKKβ, TBK1, IFIT1, IFI44, MX1 and ISG15 were detected by qRT-PCR, which showed a significantly stronger response at early infection under 20 °C. These results provided fundamental resources for subsequent in-depth research on the HIRRV infection mechanism and the antiviral immunity of flounder, and also gives evidences for the high mortality of HIRRV-infected flounder under low temperature.

PLA2R1 Inhibits Differentiated Thyroid Cancer Proliferation and Migration via the FN1-Mediated ITGB1/FAK Axis

PLA2R1 is a novel gene that is aberrantly expressed in a variety of malignancies. However, the role and mechanism of PLA2R1 in thyroid cancer has not been elucidated. We aimed to uncover the underlying mechanism of PLA2R1 in thyroid cancer. We collected 115 clinical specimens, including 54 tumor tissues and 61 para-cancerous tissues, who underwent surgical treatment at Shanghai Tenth Hospital. Immunohistochemical staining was used to evaluate PLA2R1 expression in differentiated thyroid cancer (DTC) tissues. The thyroid cancer cell lines 8505c and FTC133 transfected with PLA2R1 overexpression or knockdown plasmids were used for CCK8 assays and a wound healing assay. Next, we conducted coimmunoprecipitation (Co-IP) experiments and western blotting to explore the underlying mechanism of PLA2R1 in regulating the growth of thyroid cancer. We discovered that the expression of PLA2R1 was lower in the tumor tissues than in para-cancerous tissues (χ² = 37.0, p < 0.01). The overexpression of PLA2R1 significantly suppressed thyroid cancer cell proliferation and migration, and both of these effects were partially attenuated by the knockdown of PLA2R1. Furthermore, the in vivo growth of DTC could be alleviated by the knockdown of PLA2R1. The mechanistic study revealed that PLA2R1 competed with FN1 for binding to ITGB1, inhibiting the FAK axis and epithelial-mesenchymal transition (EMT). We speculate that PLA2R1 might be a promising marker and a novel therapeutic target for thyroid cancer.

The Role of Paxillin Aberrant Expression in Cancer and Its Potential as a Target for Cancer Therapy

Paxillin is a multi-domain adaptor protein. As an important member of focal adhesion (FA) and a participant in regulating cell movement, paxillin plays an important role in physiological processes such as nervous system development, embryonic development, and vascular development. However, increasing evidence suggests that paxillin is aberrantly expressed in many cancers. Many scholars have also recognized that the abnormal expression of paxillin is related to the prognosis, metastases, invasion, survival, angiogenesis, and other aspects of malignant tumors, suggesting that paxillin may be a potential cancer therapeutic target. Therefore, the study of how aberrant paxillin expression affects the process of tumorigenesis and metastasis will help to develop more efficacious antitumor drugs. Herein, we review the structure of paxillin and its function and expression in tumors, paying special attention to the multifaceted effects of paxillin on tumors, the mechanism of tumorigenesis and progression, and its potential role in tumor therapy. We also hope to provide a reference for the clinical prognosis and development of new tumor therapeutic targets.

Dual roles of FAK in tumor angiogenesis: A review focused on pericyte FAK

Focal adhesion kinase (FAK), also known as protein tyrosine kinase 2 (PTK2), is a ubiquitously expressed non-receptor tyrosine kinase, that plays a pivotal role in integrin-mediated signal transduction. Endothelial FAK is upregulated in many types of cancer and promotes tumorigenesis and tumor progression. However, recent studies have shown that pericyte FAK has the opposite effect. This review article dissects the mechanisms, by which endothelial cells (ECs) and pericyte FAK regulate angiogenesis, with an emphasis on the Gas6/Axl pathway. In particular, this article discusses the role of pericyte FAK loss on angiogenesis during tumorigenesis and metastasis. In addition, the existing challenges and future application of drug-based anti-FAK targeted therapies will be discussed to provide a theoretical basis for further development and use of FAK inhibitors.

Functional roles of SRC signaling in pancreatic cancer: Recent insights provide novel therapeutic opportunities

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant disease with a 5-year survival rate of <10%. Aberrant activation or elevated expression of the tyrosine kinase c-SRC (SRC) is frequently observed in PDAC and is associated with a poor prognosis. Preclinical studies have revealed a multifaceted role for SRC activation in PDAC, including promoting chronic inflammation, tumor cell proliferation and survival, cancer cell stemness, desmoplasia, hypoxia, angiogenesis, invasion, metastasis, and drug resistance. Strategies to inhibit SRC signaling include suppressing its catalytic activity, inhibiting protein stability, or by interfering with signaling components of the SRC signaling pathway including suppressing protein interactions of SRC. In this review, we discuss the molecular and immunological mechanisms by which aberrant SRC activity promotes PDAC tumorigenesis. We also provide a comprehensive update of SRC inhibitors in the clinic, and discuss the clinical challenges associated with targeting SRC in pancreatic cancer.

Mechanical homeostasis imbalance in hepatic stellate cells activation and hepatic fibrosis

Chronic liver disease or repeated damage to hepatocytes can give rise to hepatic fibrosis. Hepatic fibrosis (HF) is a pathological process of excessive sedimentation of extracellular matrix (ECM) proteins such as collagens, glycoproteins, and proteoglycans (PGs) in the hepatic parenchyma. Changes in the composition of the ECM lead to the stiffness of the matrix that destroys its inherent mechanical homeostasis, and a mechanical homeostasis imbalance activates hepatic stellate cells (HSCs) into myofibroblasts, which can overproliferate and secrete large amounts of ECM proteins. Excessive ECM proteins are gradually deposited in the Disse gap, and matrix regeneration fails, which further leads to changes in ECM components and an increase in stiffness, forming a vicious cycle. These processes promote the occurrence and development of hepatic fibrosis. In this review, the dynamic process of ECM remodeling of HF and the activation of HSCs into mechanotransduction signaling pathways for myofibroblasts to participate in HF are discussed. These mechanotransduction signaling pathways may have potential therapeutic targets for repairing or reversing fibrosis.

A luciferase fragment complementation assay to detect focal adhesion kinase (FAK) signaling events

Integrin Adhesion Complexes (IACs) serve as links between the cytoskeleton and extracellular environment, acting as mechanosensing and signaling hubs. As such, IACs participate in many aspects of cellular motility, tissue morphogenesis, anchorage-dependent growth and cell survival. Focal Adhesion Kinase (FAK) has emerged as a critical organizer of IAC signaling events due to its early recruitment and diverse substrates, and thus has become a genetic and therapeutic target. Here we present the design and characterization of simple, reversible, and scalable Bimolecular Complementation sensors to monitor FAK phosphorylation in living cells. These probes provide novel means to quantify IAC signaling, expanding on the currently available toolkit for interrogating FAK phosphorylation during diverse cellular processes.

S100A6 Protein-Expression and Function in Norm and Pathology

S100A6, also known as calcyclin, is a calcium-binding protein belonging to the S100 protein family. It was first identified and purified more than 30 years ago. Initial structural studies, focused mostly on the mode and affinity of Ca²⁺ binding and resolution of the resultant conformational changes, were soon complemented by research on its expression, localization and identification of binding partners. With time, the use of biophysical methods helped to resolve the structure and versatility of S100A6 complexes with some of its ligands. Meanwhile, it became clear that S100A6 expression was altered in various pathological states and correlated with the stage/progression of many diseases, including cancers, indicative of its important, and possibly causative, role in some of these diseases. This, in turn, prompted researchers to look for the mechanism of S100A6 action and to identify the intermediary signaling pathways and effectors. After all these years, our knowledge on various aspects of S100A6 biology is robust but still incomplete. The list of S100A6 ligands is growing all the time, as is our understanding of the physiological importance of these interactions. The present review summarizes available data concerning S100A6 expression/localization, interaction with intracellular and extracellular targets, involvement in Ca²⁺-dependent cellular processes and association with various pathologies.

Comparison of decellularization protocols for cultured cell-derived extracellular matrix-Effects on decellularization efficacy, extracellular matrix retention, and cell functions

The in vitro reconstruction of the extracellular matrix (ECM) is required in tissue engineering and regenerative medicine because the ECM can regulate cell functions in vivo. For ECM reconstruction, a decellularization technique is used. ECM reconstructed by decellularization (dECM) is prepared from tissues/organs and cultured cells. Although decellularization methods have been optimized for tissue-/organ-derived dECM, the methods for cultured cell-derived dECM have not yet been optimized. Here, two physical (osmotic shocks) and five chemical decellularization methods are compared. The decellularization efficacies were changed according to the decellularization methods used. Among them, only the Triton X-100 and Tween 20 treatments could not decellularize completely. Additionally, when the efficacies were compared among different types of cells (monolayered cells with/without strong cell adhesion, multilayered cells), the efficacies were decreased for multilayered cells or cells with strong cell adhesion. Retained ECM contents tended to be greater in the dECM prepared by osmotic shocks than in those prepared by chemical methods. The contents impacted cell adhesion, shapes, growth and intracellular signal activation on the dECM. The comparison would be helpful for the optimization of decellularization methods for cultured cells, and it could also provide new insights into developing milder decellularization methods for tissues and organs.

Bovine holo-lactoferrin inhibits migration and invasion in MDA-MB-231 breast cancer cells

PURPOSE

Breast cancer is the most common malignancy in developed countries and the main cause of deaths in women worldwide. Lactoferrin (Lf) is an iron-binding protein constituted for a single polypeptide chain that is folded into two symmetrical lobes that bind Fe²⁺ or Fe³⁺. Lf has the ability to reversibly bind Fe³⁺ and is found free of Fe³⁺ (Apo-Lf) or associated with Fe³⁺ (Holo-Lf) with a different three-dimensional conformation. However, the role of bovine Apo-Lf (Apo-BLf) and bovine Holo-Lf (Holo-BLf) in the migration and invasion induced by linoleic acid (LA) and fetal bovine serum (FBS), as well as in the expression of mesenchymal and epithelial proteins in breast cancer cells has not been studied.

METHODS AND RESULTS

Scratch wound assays demonstrated that Holo-BLf and Apo-BLf do not induce migration, however they differentially inhibit the migration induced by FBS and LA in breast cancer cells MDA-MB-231. Western blot, invasion, zymography and immunofluorescence confocal microscopy assays demonstrated that Holo-BLf partly inhibit the invasion, FAK phosphorylation at tyrosine (Tyr)-397 and MMP-9 secretion, whereas it increased the number and size of focal adhesions induced by FBS in MDA-MB-231 cells. Moreover, Holo-BLf induced a slight increase of E-cadherin expression in MCF-7 cells, and inhibited vimentin expression in MCF-7 and MDA-MB-231 breast cancer cells.

CONCLUSION

Holo-BLf inhibits cellular processes that mediate the invasion process in breast cancer cells.

A novel Pyk2-derived peptide inhibits invadopodia-mediated breast cancer metastasis

Dissemination of cancer cells from the primary tumor into distant body tissues and organs is the leading cause of death in cancer patients. While most clinical strategies aim to reduce or impede the growth of the primary tumor, no treatment to eradicate metastatic cancer exists at present. Metastasis is mediated by feet-like cytoskeletal structures called invadopodia which allow cells to penetrate through the basement membrane and intravasate into blood vessels during their spread to distant tissues and organs. The non-receptor tyrosine kinase Pyk2 is highly expressed in breast cancer, where it mediates invadopodia formation and function via interaction with the actin-nucleation-promoting factor cortactin. Here, we designed a cell-permeable peptide inhibitor that contains the second proline-rich region (PRR2) sequence of Pyk2, which binds to the SH3 domain of cortactin and inhibits the interaction between Pyk2 and cortactin in invadopodia. The Pyk2-PRR2 peptide blocks spontaneous lung metastasis in immune-competent mice by inhibiting cortactin tyrosine phosphorylation and actin polymerization-mediated maturation and activation of invadopodia, leading to reduced MMP-dependent tumor cell invasiveness. The native structure of the Pyk2-PRR2:cortactin-SH3 complex was determined using nuclear magnetic resonance (NMR), revealing an extended class II interaction surface spanning the canonical binding groove and a second hydrophobic surface which significantly contributes to ligand affinity. Using structure-guided design, we created a mutant peptide lacking critical residues involved in binding that failed to inhibit invadopodia maturation and function and consequent metastatic dissemination in mice. Our findings shed light on the specific molecular interactions between Pyk2 and cortactin and may lead to the development of novel strategies for preventing dissemination of primary breast tumors predicted at the time of diagnosis to be highly metastatic, and of secondary tumors that have already spread to other parts of the body.

Oxidative stress-induced FAK activation contributes to uterine serous carcinoma aggressiveness

Uterine serous carcinoma (USC) is an aggressive form of endometrial cancer (EC), characterized by its high propensity for metastases. In fact, while endometrioid endometrial carcinoma (EEC), which accounts for 85% of EC, presents a good prognosis, USC is the most frequently fatal. Herein, we used for the first time a peptide-based tyrosine-kinase-activity profiling approach to quantify the changes in tyrosine kinase activation between USC and EEC. Among the tyrosine kinases highly activated in USC, we identified focal adhesion kinase (FAK). We conducted mechanistic studies using cellular models. In a USC cell line, targeting FAK either by inhibitors PF-573228 and defactinib (VS-6063) or by gene silencing limits 3D cell growth and reduces cell migration. Moreover, results from our studies suggest that oxidative stress is increased in USC tumors compared to EEC ones. Reactive oxygen species (ROS) induce tyrosine phosphorylation of FAK and a concomitant tyrosine phosphorylation of paxillin, a mediator of FAK signal transduction. Mechanistically, by tracking hundreds of individual cells per condition, we show that ROS increased cell distance and migration velocity, highlighting the role of ROS-FAK-PAX signaling in cell migration. Both defactinib and ROS scavenger N-acetylcysteine (NAC) revert this effect, pointing toward ROS as potential culprits for the increase in USC cell motility. A proof of concept of the role of FAK in controlling cell growth was obtained in in vivo experiments using cancer-tissue-originated spheroids (CTOS) and a patient-derived orthotopic xenograft model (orthoxenograft/PDOX). Defactinib reduces cell proliferation and protein oxidation, supporting a pro-tumoral antioxidant role of FAK, whereas antioxidant NAC reverts FAK inhibitor effects. Overall, our data points to ROS-mediated FAK activation in USC as being responsible for the poor prognosis of this tumor type and emphasize the potential of FAK inhibition for USC treatment.

STIM1 promotes IPEC-J2 porcine epithelial cell restitution by TRPC1 signaling

Intestinal epithelial restitution is partly dependent on cell migration, which reseals superficial wounding after injury. Here, we tested the hypothesis that stromal interaction molecule 1(STIM1) regulates porcine intestinal epithelial cell migration by activating transient receptor potential canonical 1 (TRPC1) signaling. Results showed that the knockdown of STIM1 repressed cell migration after wounding, reduced the protein concentration of STIM1 and TRPC1, and decreased the inositol trisphosphate (IP3) content in IPEC-J2 cells (p < 0.05). However, overexpression of STIM1 obtained opposite results (p < 0.05). The inhibition of TRPC1 activity by treatment with SKF96365 in cells overexpressing wild-type and mutant STIM1 attenuated the STIM1 overexpression-induced increase of cell migration, STIM1, TRPC1 and IP3 (p < 0.05). In addition, polyamine depletion caused by α-difluoromethylornithine (DFMO) resulted in the decrease of above-mentioned parameters, and exogenous polyamine could attenuate the negative effects of DFMO on IPEC-J2 cells (p < 0.05). Moreover, the overexpression of STIM1 could rescue cell migration, the protein level of STIM1 and TRPC1, and IP3 content in polyamine-deficient IPEC-J2 cells (p < 0.05). These results indicated that STIM1 could enhance porcine intestinal epithelial cell migration via the TRPC1 signaling pathway. Inhibition of cell migration by polyamine depletion resulted from the reduction of STIM1 activity.

Design, synthesis, and biological evaluation of potent FAK-degrading PROTACs

FAK mediated tumour cell migration, invasion, survival, proliferation and regulation of tumour stem cells through its kinase-dependent enzymatic functions and kinase-independent scaffolding functions. At present, the development of FAK PROTACs has become one of the hotspots in current pharmaceutical research to solve above problems. Herein, we designed and synthesised a series of FAK-targeting PROTACs consisted of PF-562271 derivative 1 and Pomalidomide. All compounds showed significant in vitro FAK kinase inhibitory activity, the IC₅₀ value of the optimised PROTAC A13 was 26.4 nM. Further, A13 exhibited optimal protein degradation (85% degradation at 10 nM). Meantime, compared with PF-562271, PROTAC A13 exhibited better antiproliferative activity and anti-invasion ability in A549 cells. More, A13 had excellent plasma stability with T_1/2 >194.8 min. There are various signs that PROTAC A13 could be useful as expand tool for studying functions of FAK in biological system and as potential therapeutic agents.

Potential Focal Adhesion Kinase Inhibitors in Management of Cancer: Therapeutic Opportunities from Herbal Medicine

Focal adhesion kinase (FAK) is a multifunctional protein involved in cellular communication, integrating and transducing extracellular signals from cell-surface membrane receptors. It plays a central role intracellularly and extracellularly within the tumor microenvironment. Perturbations in FAK signaling promote tumor occurrence and development, and studies have revealed its biological behavior in tumor cell proliferation, migration, and adhesion. Herein we provide an overview of the complex biology of the FAK family members and their context-dependent nature. Next, with a focus on cancer, we highlight the activities of FAK signaling in different types of cancer and how knowledge of them is being used for screening natural compounds used in herbal medicine to fight tumor development.

ZINC40099027 promotes monolayer circular defect closure by a novel pathway involving cytosolic activation of focal adhesion kinase and downstream paxillin and ERK1/2

ZINC40099027 (ZN27) is a specific focal adhesion kinase (FAK) activator that promotes murine mucosal wound closure after ischemic or NSAID-induced injury. Diverse motogenic pathways involve FAK, but the direct consequences of pure FAK activation have not been studied, and how ZN27-induced FAK activation stimulates wound closure remained unclear. We investigated signaling and focal adhesion (FA) turnover after FAK activation by ZN27 in Caco-2 cells, confirming key results in CCD841 cells. ZN27 increased Caco-2 FAK-Y-397, FAK-Y-576/7, paxillin-Y-118, and ERK 1/2 phosphorylation and decreased FAK-Y-925 phosphorylation, without altering FAK-Y-861, p38, Jnk, or Akt phosphorylation. ZN27 increased FAK-paxillin interaction while decreasing FAK-Grb2 association. ZN27 increased membrane-associated FAK-Y-397 and FAK-Y-576/7 phosphorylation and paxillin-Y-118 and ERK 1/2 phosphorylation but decreased FAK-Y-925 phosphorylation without altering Src or Grb2. Moreover, ZN27 increased the fluorescence intensity of GFP-FAK and pFAK-Y397 in FAs and increased the total number of FAs but reduced their size in GFP-FAK-transfected Caco-2 cells, consistent with increased FA turnover. In contrast, FAK-Y397F transfection prevented ZN27 effects on FAK size and number and FAK and pFAK fluorescent intensity in FAs. We confirmed the proposed FAK/paxillin/ERK pathway using PP2 and U0126 to block Src and MEK1/2 in Caco-2 and CCD841 cells. These results suggest that ZN27 promotes intestinal epithelial monolayer defect closure by stimulating autophosphorylation of FAK in the cytosol, distinct from classical models of FAK activation in the FA. Phosphorylated FAK translocates to the membrane, where its downstream substrates paxillin and ERK are phosphorylated, leading to FA turnover and human intestinal epithelial cell migration.

Involvement of the extracellular matrix and integrin signalling proteins in skeletal muscle glucose uptake

Whole-body euglycaemia is partly maintained by two cellular processes that encourage glucose uptake in skeletal muscle, the insulin- and contraction-stimulated pathways, with research suggesting convergence between these two processes. The normal structural integrity of the skeletal muscle requires an intact actin cytoskeleton as well as integrin-associated proteins, and thus those structures are likely fundamental for effective glucose uptake in skeletal muscle. In contrast, excessive extracellular matrix (ECM) remodelling and integrin expression in skeletal muscle may contribute to insulin resistance owing to an increased physical barrier causing reduced nutrient and hormonal flux. This review explores the role of the ECM and the actin cytoskeleton in insulin- and contraction-mediated glucose uptake in skeletal muscle. This is a clinically important area of research given that defects in the structural integrity of the ECM and integrin-associated proteins may contribute to loss of muscle function and decreased glucose uptake in type 2 diabetes.