Focal adhesion kinase: a regulator of focal adhesion dynamics and cell movement

Pannexins in the musculoskeletal system: new targets for development and disease progression

During cell differentiation, growth, and development, cells can respond to extracellular stimuli through communication channels. Pannexin (Panx) family and connexin (Cx) family are two important types of channel-forming proteins. Panx family contains three members (Panx1-3) and is expressed widely in bone, cartilage and muscle. Although there is no sequence homology between Panx family and Cx family, they exhibit similar configurations and functions. Similar to Cxs, the key roles of Panxs in the maintenance of physiological functions of the musculoskeletal system and disease progression were gradually revealed later. Here, we seek to elucidate the structure of Panxs and their roles in regulating processes such as osteogenesis, chondrogenesis, and muscle growth. We also focus on the comparison between Cx and Panx. As a new key target, Panxs expression imbalance and dysfunction in muscle and the therapeutic potentials of Panxs in joint diseases are also discussed.

Protective effect of tretinoin on cervical cancer growth and proliferation through downregulation of pFAK2 expression

BACKGROUND

Cervical cancer, a life-threatening disease, is the seventh most commonly detected cancer among women throughout the world. The present study investigated the effect of tretinoin on cervical cancer growth and metastasis in vitro and in vivo in the mice model.

MATERIALS AND METHODS

Cell Counting Kit-8, clonogenic survival, and transwell chamber assays were used for determination cells proliferation, colony formation, and invasiveness. Western blotting assay was used for assessment of protein expression whereas AutoDock Vina and Discovery studio software for in silico studies.

RESULTS

Tretinoin treatment significantly (p < .05) reduced the proliferation of HT-3 and Caski cells in concentration-based manner. Incubation with tretinoin caused a significant decrease in clonogenic survival of HT-3 and Caski cells compared with the control cultures. The invasive potential of HT-3 cells was decreased to 18%, whereas that of Caski cells to 21% on treatment with 8 μM concentration of tretinoin. In HT-3 cells, tretinoin treatment led to a prominent reduction in p-focal adhesion kinase (FAK), matrix metalloproteinases (MMP)-2, and MMP-9 expression in HT-3 cells. Treatment of the cervical cancer mice model with tretinoin led to a prominent decrease in tumor growth. The metastasis of tumor in model cervical cancer mice group was effectively inhibited in spleen, intestines, and peritoneal cavity. In silico studies showed that tretinoin interacts with alanine, proline, isoleucine, and glycine amino acid residues of FAK protein to block its activation. The 2-dimensional diagram of interaction of tretinoin with FAK protein revealed that tretinoin binds to alanine and glycine amino acids through conventional hydrogen bonding.

CONCLUSION

In summary, tretinoin suppressed the proliferation, colony formation, and invasiveness of cervical cancer cells in vitro. It decreased the expression of activated focal adhesion kinase, MMP-2, and MMP-9 in HT-3 cells in dose-dependent manner. In silico studies showed that tretinoin interacts with alanine and glycine amino acids through conventional hydrogen bonding. In vivo data demonstrated that treatment of the cervical cancer mice model with tretinoin led to a prominent decrease in tumor growth. Therefore, tretinoin can be developed as an effective therapeutic agent for cervical cancer treatment.

Molecular and functional characterization of reversible-sunitinib-tolerance state in human renal cell carcinoma

Therapy failure with the tyrosine kinase inhibitor (TKI) sunitinib remains a great challenge in metastatic renal cell carcinoma (mRCC). Growing evidence indicates that the tumour subpopulation can enter a transient, non-mutagenic drug-tolerant state to endure the treatment underlying the minimal residual disease and tumour relapse. Drug tolerance to sunitinib remains largely unexplored in RCC. Here, we show that sunitinib-tolerant 786-O/S and Caki-2/S cells are induced by prolonged drug treatment showing reduced drug sensitivity, enhanced clonogenicity, and DNA synthesis. Sunitinib-tolerance developed via dynamic processes, including (i) engagement of c-MET and AXL pathways, (ii) alteration of stress-induced p38 kinase and pro-survival BCL-2 signalling, (iii) extensive actin remodelling, which was correlated with activation of focal adhesion proteins. Remarkably, the acute drug response in both sensitive and sunitinib-tolerant cell lines led to dramatic fine-tuning of the actin-cytoskeleton and boosted cellular migration and invasion, indicating that the drug-response might depend on cell state transition rather than pre-existing mutations. The drug-tolerant state was transiently acquired, as the cells resumed initial drug sensitivity after >10 passages under drug withdrawal, reinforcing the concept of dynamic regulation and phenotypic heterogeneity. Our study described molecular events contributing to the reversible switch into sunitinib-tolerance, providing possible novel therapeutic opportunities in RCC.

The c-Abl-RACK1-FAK signaling axis promotes renal fibrosis in mice through regulating fibroblast-myofibroblast transition

BACKGROUND

Renal fibrosis is a prevalent manifestation of chronic kidney disease (CKD), and effective treatments for this disease are currently lacking. Myofibroblasts, which originate from interstitial fibroblasts, aggregate in the renal interstitium, leading to significant accumulation of extracellular matrix and impairment of renal function. The nonreceptor tyrosine kinase c-Abl (encoded by the Abl1 gene) has been implicated in the development of renal fibrosis. However, the precise role of c-Abl in this process and its involvement in fibroblast-myofibroblast transition (FMT) remain poorly understood.

METHODS

To investigate the effect of c-Abl in FMT during renal fibrosis, we investigated the expression of c-Abl in fibrotic renal tissues of patients with CKD and mouse models. We studied the phenotypic changes in fibroblast or myofibroblast-specific c-Abl conditional knockout mice. We explored the potential targets of c-Abl in NRK-49F fibroblasts.

RESULTS

In this study, fibrotic mouse and cell models demonstrated that c-Abl deficiency in fibroblasts mitigated fibrosis by suppressing fibroblast activation, fibroblast-myofibroblast transition, and extracellular matrix deposition. Mechanistically, c-Abl maintains the stability of the RACK1 protein, which serves as a scaffold for proteins such as c-Abl and focal adhesion kinase at focal adhesions, driving fibroblast activation and differentiation during renal fibrosis. Moreover, specifically targeting c-Abl deletion in renal myofibroblasts could prove beneficial in established kidney fibrosis by reducing RACK1 expression and diminishing the extent of fibrosis.

CONCLUSIONS

Our findings suggest that c-Abl plays a pathogenic role in interstitial fibrosis through the regulation of RACK1 protein stabilization and myofibroblast differentiation, suggesting a promising strategy for the treatment of CKD.

Bacopa monnieri phytochemicals regulate fibroblast cell migration via modulation of focal adhesions

The Bacopa monnieri plant contains phytochemicals that have been used extensively in traditional medicine to treat various diseases. More recently it has been shown to accelerate wound healing, though its mechanism of action is largely unknown. Here we investigated the cellular pathways activated by a methanol extract of Bacopa monnieri in human dermal fibroblasts, which play many critical roles in the wound healing program. Gene expression analysis revealed that the Bacopa monnieri extract can modulate multiple processes involved in the wound healing program such as migration, proliferation, and angiogenesis. We discovered that the extract can increase migration of fibroblasts via modulating the size and number of focal adhesions. Bacopa monnieri-mediated changes in focal adhesions are dependent on α5β1 integrin activation and subsequent phosphorylation of focal adhesion kinase (FAK). Altogether our results suggest that Bacopa monnieri extract could enhance the wound healing rate via modulating fibroblast migration into the wound bed.

Stiffness assisted cell-matrix remodeling trigger 3D mechanotransduction regulatory programs

Engineered matrices provide a valuable platform to understand the impact of biophysical factors on cellular behavior such as migration, proliferation, differentiation, and tissue remodeling, through mechanotransduction. While recent studies have identified some mechanisms of 3D mechanotransduction, there is still a critical knowledge gap in comprehending the interplay between 3D confinement, ECM properties, and cellular behavior. Specifically, the role of matrix stiffness in directing cellular fate in 3D microenvironment, independent of viscoelasticity, microstructure, and ligand density remains poorly understood. To address this gap, we designed a nanoparticle crosslinker to reinforce collagen-based hydrogels without altering their chemical composition, microstructure, viscoelasticity, and density of cell-adhesion ligand and utilized it to understand cellular dynamics. This crosslinking mechanism utilizes nanoparticles as crosslink epicenter, resulting in 10-fold increase in mechanical stiffness, without other changes. Human mesenchymal stem cells (hMSCs) encapsulated in 3D responded to mechanical stiffness by displaying circular morphology on soft hydrogels (5 kPa) and elongated morphology on stiff hydrogels (30 kPa). Stiff hydrogels facilitated the production and remodeling of nascent extracellular matrix (ECM) and activated mechanotransduction cascade. These changes were driven through intracellular PI3AKT signaling, regulation of epigenetic modifiers and activation of YAP/TAZ signaling. Overall, our study introduces a unique biomaterials platform to understand cell-ECM mechanotransduction in 3D for regenerative medicine as well as disease modelling.

Thy-1 (CD90)-regulated cell adhesion and migration of mesenchymal cells: insights into adhesomes, mechanical forces, and signaling pathways

Cell adhesion and migration depend on the assembly and disassembly of adhesive structures known as focal adhesions. Cells adhere to the extracellular matrix (ECM) and form these structures via receptors, such as integrins and syndecans, which initiate signal transduction pathways that bridge the ECM to the cytoskeleton, thus governing adhesion and migration processes. Integrins bind to the ECM and soluble or cell surface ligands to form integrin adhesion complexes (IAC), whose composition depends on the cellular context and cell type. Proteomic analyses of these IACs led to the curation of the term adhesome, which is a complex molecular network containing hundreds of proteins involved in signaling, adhesion, and cell movement. One of the hallmarks of these IACs is to sense mechanical cues that arise due to ECM rigidity, as well as the tension exerted by cell-cell interactions, and transduce this force by modifying the actin cytoskeleton to regulate cell migration. Among the integrin/syndecan cell surface ligands, we have described Thy-1 (CD90), a GPI-anchored protein that possesses binding domains for each of these receptors and, upon engaging them, stimulates cell adhesion and migration. In this review, we examine what is currently known about adhesomes, revise how mechanical forces have changed our view on the regulation of cell migration, and, in this context, discuss how we have contributed to the understanding of signaling mechanisms that control cell adhesion and migration.

Unraveling Connective Tissue Growth Factor as a Therapeutic Target and Assessing Kahweol as a Potential Drug Candidate in Triple-Negative Breast Cancer Treatment

Triple-negative breast cancer (TNBC) is characterized by aggressive behavior and limited treatment options, necessitating the identification of novel therapeutic targets. In this study, we investigated the clinical significance of connective tissue growth factor (CTGF) as a prognostic marker and explored the potential therapeutic effects of kahweol, a coffee diterpene molecule, in TNBC treatment. Initially, through a survival analysis on breast cancer patients from The Cancer Genome Atlas (TCGA) database, we found that CTGF exhibited significant prognostic effects exclusively in TNBC patients. To gain mechanistic insights, we performed the functional annotation and gene set enrichment analyses, revealing the involvement of CTGF in migratory pathways relevant to TNBC treatment. Subsequently, in vitro experiments using MDA-MB 231 cells, a representative TNBC cell line, demonstrated that recombinant CTGF (rCTGF) administration enhanced cell motility, whereas CTGF knockdown using CTGF siRNA resulted in reduced motility. Notably, rCTGF restored kahweol-reduced cell motility, providing compelling evidence for the role of CTGF in mediating kahweol's effects. At the molecular level, kahweol downregulated the protein expression of CTGF as well as critical signaling molecules, such as p-ERK, p-P38, p-PI3K/AKT, and p-FAK, associated with cell motility. In summary, our findings propose CTGF as a potential prognostic marker for guiding TNBC treatment and suggest kahweol as a promising antitumor compound capable of regulating CTGF expression to suppress cell motility in TNBC. These insights hold promise for the development of targeted therapies and improved clinical outcomes for TNBC patients.

Insights on the functional dualism of nitric oxide in the hallmarks of cancer

Nitric oxide (NO), a gaseous radical, governs a variety of physiological and pathological processes, including cancer, pro-inflammatory signalling, and vasodilation. The family of nitric oxide synthases (NOS), which comprises the constitutive forms, nNOS and eNOS, and the inducible form, iNOS, produces NO enzymatically. Additionally, NO can be generated non-enzymatically from the nitrate-nitrite-NO pathway. The anti- and pro-oxidant properties of NO and its functional dualism in cancer is due to its highly reactive nature. Numerous malignancies have NOS expression, which interferes with the tumour microenvironment to modulate the tumour's growth in both favourable and unfavourable ways. NO regulates a number of mechanisms in the tumour microenvironment, including metabolism, cell cycle, DNA repair, angiogenesis, and apoptosis/necrosis, depending on its concentration and spatiotemporal profile. This review focuses on the bi-modal impact of nitric oxide on the alteration of a few cancer hallmarks.

Focal adhesion kinase (FAK): its structure, characteristics, and signaling in skeletal system

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase and distributes important regulatory functions in skeletal system. Mesenchymal stem cell (MSC) possesses significant migration and differentiation capacity, is an important source of distinctive bone cells production and a prominent bone development pathway. MSC has a wide range of applications in tissue bioengineering and regenerative medicine, and is frequently employed for hematopoietic support, immunological regulation, and defect repair, although current research is insufficient. FAK has been identified to cross-link with many other keys signaling pathways in bone biology and is considered as a fundamental "crossroad" on the signal transduction pathway and a "node" in the signal network to mediate MSC lineage development in skeletal system. In this review, we summarized the structure, characteristics, cellular signaling, and the interactions of FAK with other signaling pathways in the skeletal system. The discovery of FAK and its mediated molecules will lead to a new knowledge of bone development and bone construction as well as considerable potential for therapeutic use in the treatment of bone-related disorders such as osteoporosis, osteoarthritis, and osteosarcoma.

Actin Cytoskeleton Polymerization and Focal Adhesion as Important Factors in the Pathomechanism and Potential Targets of Mucopolysaccharidosis Treatment

The main approach used in the current therapy of mucopolysaccharidosis (MPS) is to reduce the levels of glycosaminoglycans (GAGs) in cells, the deposits considered to be the main cause of the disease. Previous studies have revealed significant differences in the expression of genes encoding proteins involved in many processes, like those related to actin filaments, in MPS cells. Since the regulation of actin filaments is essential for the intracellular transport of specific molecules, the process which may affect the course of MPSs, the aim of this study was to evaluate the changes that occur in the actin cytoskeleton and focal adhesion in cells derived from patients with this disease, as well as in the MPS I mouse model, and to assess whether they could be potential therapeutic targets for different MPS types. Western-blotting, flow cytometry and transcriptomic analyses were employed to address these issues. The levels of the key proteins involved in the studied processes, before and after specific treatment, were assessed. We have also analyzed transcripts whose levels were significantly altered in MPS cells. We identified genes whose expressions were changed in the majority of MPS types and those with particularly highly altered expression. For the first time, significant changes in the expression of genes involved in the actin cytoskeleton structure/functions were revealed which may be considered as an additional element in the pathogenesis of MPSs. Our results suggest the possibility of using the actin cytoskeleton as a potential target in therapeutic approaches for this disease.

Pak1 pathway hyper-activation mediates resistance to endocrine therapy and CDK4/6 inhibitors in ER+ breast cancer

Cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) have been approved in combination with endocrine therapy (ET) to treat estrogen receptor-positive (ER+) metastatic breast cancer (BC). However, drug resistance represents the leading cause of breast cancer patients mortality. This study aimed to identify novel resistance mechanisms to ER antagonists in combination with CDK4/6 inhibitors. We generated two ER+ BC cell lines, T47D and MCF7, resistant to the combination of the ER antagonist fulvestrant and CDK4/6i abemaciclib, named T47D-FAR and MCF7-FAR. Transcriptomic analysis revealed common up-regulation of genes involved in MAPK and epithelial to mesenchymal transition (EMT) pathways in FAR cells, sustaining their hyper-invasive phenotype and increased anchorage-independent growth, compared to sensitive cells. FAR cells showed higher p21-activated kinase 1 (Pak1) expression and phosphorylation levels than parental cells. PAK1 knockdown by siRNAs hampered cell proliferation, reduced anchorage-independent growth and invasive properties of T47D-FAR and MCF7-FAR, re-sensitizing them to fulvestrant and abemaciclib. Conversely, over-expression of PAK1 in MCF7 and T47D cells increased tumor spheroids' growth and invasion and reduced sensitivity to fulvestrant and abemaciclib, confirming its role in inducing drug resistance. Finally, treatment with Pak1 inhibitors, PF-3758309 (PF309) and NVS-PAK1-1, restored cell sensitivity to fulvestrant and abemaciclib of MCF7-FAR and T47D-FAR cells, both in vitro and in vivo. In conclusion, our data suggested a pivotal role for Pak1 in resistance to ET and CDK4/6i in ER+ breast cancers. These data might promote the rationale for the development of novel Pak1 inhibitors for treatment of patients with ER+ BC progressing on ET plus CDK4/6i.

Angiogenesis in the Outer Membrane of Chronic Subdural Hematomas through Thrombin-Cleaved Osteopontin and the Integrin α9 and Integrin β1 Signaling Pathways

BACKGROUND

A chronic subdural hematoma (CSDH) is considered to be an inflammatory and angiogenic disease. The CSDH outer membrane, which contains inflammatory cells, plays an important role in CSDH development. Osteopontin (OPN) is an extracellular matrix protein that is cleaved by thrombin, generating the N-terminal half of OPN, which is prominently involved in integrin signal transduction. We explored the expression of the N-terminal half of OPN in CSDH fluid and the expression of integrins α9 and β1 and the downstream components of the angiogenic signaling pathways in the outer membrane of CSDHs.

METHODS

Twenty samples of CSDH fluid and eight samples of CSDH outer membrane were collected from patients suffering from CSDHs. The concentrations of the N-terminal half of OPN in CSDH fluid samples were measured using ELISA kits. The expression levels of integrins α9 and β1, vinculin, talin-1, focal adhesion kinase (FAK), paxillin, α-actin, Src and β-actin were examined by Western blot analysis. The expression levels of integrins α9 and β1, FAK and paxillin were also examined by immunohistochemistry. We investigated whether CSDH fluid could activate FAK in cultured endothelial cells in vitro.

RESULTS

The concentration of the N-terminal half of OPN in CSDH fluid was significantly higher than that in the serum. Western blot analysis confirmed the presence of these molecules. In addition, integrins α9 and β1, FAK and paxillin were localized in the endothelial cells of vessels within the CSDH outer membrane. FAK was significantly phosphorylated immediately after treatment with CSDH fluid.

CONCLUSION

Our data suggest that the N-terminal half of OPN in CSDH fluid promotes neovascularization in endothelial cells through integrins α9 and β1. The N-terminal half of OPN, which is part of the extracellular matrix, plays a critical role in the promotion of CSDHs.

Therapeutic targeting of anoikis resistance in cutaneous melanoma metastasis

The acquisition of resistance to anoikis, the cell death induced by loss of adhesion to the extracellular matrix, is an absolute requirement for the survival of disseminating and circulating tumour cells (CTCs), and for the seeding of metastatic lesions. In melanoma, a range of intracellular signalling cascades have been identified as potential drivers of anoikis resistance, however a full understanding of the process is yet to be attained. Mechanisms of anoikis resistance pose an attractive target for the therapeutic treatment of disseminating and circulating melanoma cells. This review explores the range of small molecule, peptide and antibody inhibitors targeting molecules involved in anoikis resistance in melanoma, and may be repurposed to prevent metastatic melanoma prior to its initiation, potentially improving the prognosis for patients.

A novel microbial and hepatic biotransformation-integrated network pharmacology strategy explores the therapeutic mechanisms of bioactive herbal products in neurological diseases: the effects of Astragaloside IV on intracerebral hemorrhage as an example

BACKGROUND

The oral bioavailability and blood-brain barrier permeability of many herbal products are too low to explain the significant efficacy fully. Gut microbiota and liver can metabolize herbal ingredients to more absorbable forms. The current study aims to evaluate the ability of a novel biotransformation-integrated network pharmacology strategy to discover the therapeutic mechanisms of low-bioavailability herbal products in neurological diseases.

METHODS

A study on the mechanisms of Astragaloside IV (ASIV) in treating intracerebral hemorrhage (ICH) was selected as an example. Firstly, the absorbed ASIV metabolites were collected by a literature search. Next, the ADMET properties and the ICH-associated targets of ASIV and its metabolites were compared. Finally, the biotransformation-increased targets and biological processes were screened out and verified by molecular docking, molecular dynamics simulation, and cell and animal experiments.

RESULTS

The metabolites (3-epi-cycloastragenol and cycloastragenol) showed higher bioavailability and blood-brain barrier permeability than ASIV. Biotransformation added the targets ASIV in ICH, including PTK2, CDC42, CSF1R, and TNF. The increased targets were primarily enriched in microglia and involved in cell migration, proliferation, and inflammation. The computer simulations revealed that 3-epi-cycloastragenol bound CSF1R and cycloastragenol bound PTK2 and CDC42 stably. The In vivo and in vitro studies confirmed that the ASIV-derived metabolites suppressed CDC42 and CSF1R expression and inhibited microglia migration, proliferation, and TNF-α secretion.

CONCLUSION

ASIV inhibits post-ICH microglia/macrophage proliferation and migration, probably through its transformed products to bind CDC42, PTK2, and CSF1R. The integrated strategy can be used to discover novel mechanisms of herbal products or traditional Chinses medicine in treating diseases.

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.

The Integrin Pathway Partially Mediates Stretch-Induced Deficits in Primary Rat Microglia

Stretch-injured microglia display significantly altered morphology, function and inflammatory-associated gene expression when cultured on a synthetic fibronectin substrate. However, the mechanism by which stretch induces these changes is unknown. Integrins, such as α5β1, mediate microglial attachment to fibronectin via the RGD binding peptide; following integrin ligation the integrin-associated signaling enzyme, focal adhesion kinase (FAK), autophosphorylates tyrosine residue 397 and mediates multiple downstream cellular processes. We therefore hypothesize that blocking the RGD binding/integrin pathway with a commercially available RGD peptide will mimic the stretch-induced morphological alterations and functional deficits in microglia. Further, we hypothesize that upregulation of stretch-inhibited downstream integrin signaling will reverse these effects. Using primary rat microglia, we tested the effects of RGD binding peptide and a FAK activator on cellular function and structure and response to stretch-injury. Similar to injured cells, RGD peptide administration significantly decreases media nitric oxide (NO) levels and iNOS expression and induced morphological alterations and migratory deficits. While stretch-injury and RGD peptide administration decreased phosphorylation of the tyrosine 397 residue on FAK, 20 nM of ZINC 40099027, an activator specific to the tyrosine 397 residue, rescued the stretch-induced decrease in FAK phosphorylation and ameliorated the injury-induced decrease in media NO levels, iNOS expression and inflammatory associated gene expression. Additionally, treatment alleviated morphological changes observed after stretch-injury and restored normal migratory behavior to control levels. Taken together, these data suggest that the integrin/FAK pathway partially mediates the stretch-injured phenotype in microglia, and may serve as a pathway to modulate microglial responses.

Amorphizing Metal Selenides-Based ROS Biocatalysts at Surface Nanolayer toward Ultrafast Inflammatory Diabetic Wound Healing

The microenvironments with high reactive-oxygen-species (ROS) levels, inflammatory responses, and oxidative-stress effects in diabetic ulcer wounds, leading to poor proliferation and differentiation of stem cells, severely inhibit their efficient healing. Here, to overcome the unbalanced multielectron reactions in ROS catalysis, we develop a cobalt selenide-based biocatalyst with an amorphous Ru@CoSe nanolayer for ultrafast and broad-spectrum catalytic ROS-elimination. Owing to the enriched electrons and more unoccupied orbitals of Ru atoms, the amorphous Ru@CoSe nanolayer-equipped biocatalyst displays excellent catalase-like kinetics (maximal reaction velocity, 23.05 μM s^-1; turnover number, 2.00 s^-1), which exceeds most of the currently reported metal compounds. The theoretical studies show that Ru atoms act as "regulators" to tune the electronic state of the Co sites and modulate the interaction of oxygen intermediates, thus improving the reversible redox properties of active sites. Consequently, the Ru@CoSe can efficiently rescue the proliferation of mesenchymal stem cells and maintain their angiogenic potential in the oxidative stress environment. In vivo experiments reveal the superior ROS-elimination ability of Ru@CoSe on the inflammatory diabetic wound. This study offers an effective nanomedicine for catalytic ROS-scavenging and ultrafast healing of inflammatory wounds and also provides a strategy to design biocatalytic metal compounds via bringing amorphous catalytic structures.

Irisin exhibits neuroprotection by preventing mitochondrial damage in Parkinson's disease

Exercise has been proposed as an effective non-pharmacological management for Parkinson's disease (PD) patients. Irisin, a recently identified myokine, is increased by exercise and plays pivotal roles in energy metabolism. However, it remains unknown whether irisin has any protective effects on PD. Here, we found that serum irisin levels of PD patients were markedly elevated after 12-week regular exercise, which had a positive correlation with improved balance function scored by Berg Balance Scale. Treatment with exogenous irisin could improve motor function, and reduce dopaminergic neurodegeneration in PD models. Meanwhile, irisin could reduce cell apoptosis by renovating mitochondrial function in PD models, which was reflected in decreased oxidative stress, increased mitochondrial complex I activity and mitochondrial content, increased mitochondrial biogenesis, and repaired mitochondrial morphology. Furthermore, irisin regulated the aforementioned aspects by upregulating downstream Akt signaling pathway and ERK1/2 signaling pathway through integrin receptors rather than directly targeting mitochondria. With the use of small-molecule inhibitors, it was found that irisin can reduce apoptosis, restore normal mitochondrial biogenesis, and improve mitochondrial morphology and dynamic balance in PD models by activating Akt signaling pathway and ERK1/2 signaling pathway. And irisin reduced oxidative stress via activating ERK1/2 signaling pathway. The results revealed that exogenous irisin conferred neuroprotection relieving apoptosis and oxidative stress, restraining mitochondrial fragmentation, and promoting mitochondrial respiration and biogenesis in PD models, and irisin exerted the aforementioned effects by activating Akt signaling pathway and ERK1/2 signaling pathway. Thus, peripherally delivered irisin might be a promising candidate for therapeutic targeting of PD.

OVOL2 impairs RHO GTPase signaling to restrain mitosis and aggressiveness of Anaplastic Thyroid Cancer

Background

Anaplastic Thyroid Cancer (ATC) is an undifferentiated and aggressive tumor that often originates from well-Differentiated Thyroid Carcinoma (DTC) through a trans-differentiation process. Epithelial-to-Mesenchymal Transition (EMT) is recognized as one of the major players of this process. OVOL2 is a transcription factor (TF) that promotes epithelial differentiation and restrains EMT during embryonic development. OVOL2 loss in some types of cancers is linked to aggressiveness and poor prognosis. Here, we aim to clarify the unexplored role of OVOL2 in ATC.

Methods

Gene expression analysis in thyroid cancer patients and cell lines showed that OVOL2 is mainly associated with epithelial features and its expression is deeply impaired in ATC. To assess OVOL2 function, we established an OVOL2-overexpression model in ATC cell lines and evaluated its effects by analyzing gene expression, proliferation, invasion and migration abilities, cell cycle, specific protein localization through immunofluorescence staining. RNA-seq profiling showed that OVOL2 controls a complex network of genes converging on cell cycle and mitosis regulation and Chromatin Immunoprecipitation identified new OVOL2 target genes.

Results

Coherently with its reported function, OVOL2 re-expression restrained EMT and aggressiveness in ATC cells. Unexpectedly, we observed that it caused G2/M block, a consequent reduction in cell proliferation and an increase in cell death. This phenotype was associated to generalized abnormalities in the mitotic spindle structure and cytoskeletal organization. By RNA-seq experiments, we showed that many pathways related to cytoskeleton and migration, cell cycle and mitosis are profoundly affected by OVOL2 expression, in particular the RHO-GTPase pathway resulted as the most interesting. We demonstrated that RHO GTPase pathway is the central hub of OVOL2-mediated program in ATC and that OVOL2 transcriptionally inhibits RhoU and RhoJ. Silencing of RhoU recapitulated the OVOL2-driven phenotype pointing to this protein as a crucial target of OVOL2 in ATC.

Conclusions

Collectively, these data describe the role of OVOL2 in ATC and uncover a novel function of this TF in inhibiting the RHO GTPase pathway interlacing its effects on EMT, cytoskeleton dynamics and mitosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02316-2.

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.

Gp35/50 mucin molecules of Trypanosoma cruzi metacyclic forms that mediate host cell invasion interact with annexin A2

Host cell invasion is a critical step for infection by Trypanosoma cruzi, the agent of Chagas disease. In natural infection, T. cruzi metacyclic trypomastigote (MT) forms establish the first interaction with host cells. The gp35/50 mucin molecules expressed in MT have been implicated in cell invasion process, but the mechanisms involved are not well understood. We performed a series of experiments to elucidate the mode of gp35/50-mediated MT internalization. Comparing two parasite strains from genetically divergent groups, G strain (TcI) and CL strain (TcVI), expressing variant forms of mucins, we demonstrated that G strain mucins participate in MT invasion. Only G strain-derived mucins bound to HeLa cells in a receptor-dependent manner and significantly inhibited G strain MT invasion. CL strain MT internalization was not affected by mucins from either strain. HeLa cell invasion by G strain MT was associated with actin recruitment and did not rely on lysosome mobilization. To examine the involvement of annexin A2, which plays a role in actin dynamic, annexin A2-depleted HeLa cells were generated. Annexin A2-deficient cell lines were significantly more resistant than wild type controls to G strain MT invasion. In a co-immunoprecipitation assay, to check whether annexin A2 might be the receptor for mucins, protein A/G magnetic beads crosslinked with monoclonal antibody to G strain mucins were incubated with detergent extracts of MT and HeLa cells. Binding of gp35/50 mucins to annexin A2 was detected. Both G strain MT and purified mucins induced focal adhesion kinase activation in HeLa cells. By confocal immunofluorescence microscopy, colocalization of invading G strain MT with clathrin was visualized. Inhibition of clathrin-coated vesicle formation reduced parasite internalization. Taken together, our data indicate that gp35/50-mediated MT invasion is accomplished through interaction with host cell annexin A2 and clathrin-dependent endocytosis.

Host cell invasion by Trypanosoma cruzi, the agent of Chagas disease, is critical for the establishment of infection. Metacyclic trypomastigote (MT) forms are responsible for the initial T. cruzi-host cell interaction. Mucin molecules expressed on MT surface have been implicated in target cell invasion process, but the underlying mechanism are not fully understood. In this study, we aimed at elucidating the mode of mucin-mediated MT internalization. We found that requirement of mucins for MT invasion is T. cruzi strain-dependent. Experiments with G strain MTs, which rely on mucins and on target cell actin for internalization, revealed that mucin molecules bind to annexin A2, a protein that plays a role in actin dynamic. Annexin A2-deficient cell lines were generated and found to be significantly more resistant than wild type controls to MT invasion. Both MT and purified mucins induced focal adhesion kinase activation in host cells. By confocal immunofluorescence microscopy, invading MT was found to colocalize with clathrin, a protein that plays a role in endocytosis. Inhibition of clathrin-coated vesicle formation reduced parasite internalization. From these data we infer that mucin-mediated MT invasion is accomplished through interaction with host cell annexin A2 and clathrin-dependent endocytosis.

Reduced Graphene Oxide Modulates the FAK-Dependent Signaling Pathway in Glioblastoma Multiforme Cells In Vitro

Aggressive invasiveness is a common feature of malignant gliomas, despite their high level of tumor heterogeneity and possible diverse cell origins. Therefore, it is important to explore new therapeutic methods. In this study, we evaluated and compared the effects of graphene (GN) and reduced graphene oxides (rGOs) on a highly invasive and neoplastic cell line, U87. The surface functional groups of the GN and rGO flakes were characterized by X-ray photoelectron spectroscopy. The antitumor activity of these flakes was obtained by using the neutral red assay and their anti-migratory activity was determined using the wound healing assay. Further, we investigated the mRNA and protein expression levels of important cell adhesion molecules involved in migration and invasiveness. The rGO flakes, particularly rGO/ATS and rGO/TUD, were found highly toxic. The migration potential of both U87 and Hs5 cells decreased, especially after rGO/TUD treatment. A post-treatment decrease in mobility and FAK expression was observed in U87 cells treated with rGO/ATS and rGO/TUD flakes. The rGO/TUD treatment also reduced β-catenin expression in U87 cells. Our results suggest that rGO flakes reduce the migration and invasiveness of U87 tumor cells and can, thus, be used as potential antitumor agents.

Ligand Mobility-Mediated Cell Adhesion and Spreading

Cells live in a highly dynamic environment where their physical connection and communication with the outside are achieved through receptor-ligands binding. Therefore, a precise knowledge of the interaction between receptors and ligands is critical for our understanding of how cells execute different biological duties. Interestingly, recent evidence has shown that the mobility of ligands at the cell-extracellular matrix (ECM) interface significantly affects the adhesion and spreading of cells, while the underlying mechanism remains unclear. Here, we present a modeling investigation to address this critical issue. Specifically, by adopting the Langevin dynamics, the random movement of ligands was captured by assigning a stochastic force along with a viscous drag on them. After that, the evolution of adhesion and subsequent spreading of cells were analyzed by considering the force-regulated binding/breakage of individual molecular bonds connecting polymerizing actin bundles inside the cell to the ECM. Interestingly, a biphasic relationship between adhesion and ligand diffusivity was predicted, resulting in maximized cell spreading at intermediate mobility of ligand molecules. In addition, this peak position was found to be dictated by the aggregation of ligands, effectively reducing their diffusivity, and how fast bond association/dissociation can occur. These predictions are in excellent agreement with our experimental observations where distinct ligand mobility was introduced by tuning the interactions between the self-assembly polymer coating and the surface.

MicroRNA-138 Abates Fibroblast Motility With Effect on Invasion of Adjacent Cancer Cells

Background

Recent studies have shown aberrant expression of micro-RNAs in cancer-associated fibroblasts (CAFs). This study aimed to investigate miR-138 dysregulation in CAFs in oral squamous cell carcinoma (OSCC) and its effects on their phenotype and invasion of adjacent OSCC cells.

Methods

Expression of miR-138 was first investigated in OSCC lesions (n = 53) and OSCC-derived CAFs (n = 15). MiR-138 mimics and inhibitors were used to functionally investigate the role of miR-138 on CAF phenotype and the resulting change in their ability to support OSCC invasion.

Results

Expression of miR-138 showed marked heterogeneity in both OSCC tissues and cultured fibroblasts. Ectopic miR-138 expression reduced fibroblasts’ motility and collagen contraction ability and suppressed invasion of suprajacent OSCC cells, while its inhibition resulted in the opposite outcome. Transcript and protein examination after modulation of miR-138 expression showed changes in CAF phenotype-specific molecules, focal adhesion kinase axis, and TGFβ1 signaling pathway.

Conclusions

Despite its heterogeneous expression, miR-138 in OSCC-derived CAFs exhibits a tumor-suppressive function.

Diffuse gastric cancer: Emerging mechanisms of tumor initiation and progression

Gastric cancer is globally the fourth leading cause of cancer-related deaths. Patients with diffuse-type gastric cancer (DGC) particularly have a poor prognosis that only marginally improved over the last decades, as conventional chemotherapies are frequently ineffective and specific therapies are unavailable. Early-stage DGC is characterized by intramucosal lesions of discohesive cells, which can be present for many years before the emergence of advanced DGC consisting of highly proliferative and invasive cells. The mechanisms underlying the key steps of DGC development and transition to aggressive tumors are starting to emerge. Novel mouse- and organoid models for DGC, together with multi-omic analyses of DGC tumors, revealed contributions of both tumor cell-intrinsic alterations and gradual changes in the tumor microenvironment to DGC progression. In this review, we will discuss how these recent findings are leading towards an understanding of the cellular and molecular mechanisms responsible for DGC initiation and malignancy, which may provide opportunities for targeted therapies.

FAK in Cancer: From Mechanisms to Therapeutic Strategies

Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, is overexpressed and activated in many cancer types. FAK regulates diverse cellular processes, including growth factor signaling, cell cycle progression, cell survival, cell motility, angiogenesis, and the establishment of immunosuppressive tumor microenvironments through kinase-dependent and kinase-independent scaffolding functions in the cytoplasm and nucleus. Mounting evidence has indicated that targeting FAK, either alone or in combination with other agents, may represent a promising therapeutic strategy for various cancers. In this review, we summarize the mechanisms underlying FAK-mediated signaling networks during tumor development. We also summarize the recent progress of FAK-targeted small-molecule compounds for anticancer activity from preclinical and clinical evidence.

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.

High TSPAN8 expression in epithelial cancer cell-derived small extracellular vesicles promote confined diffusion and pronounced uptake

Small extracellular vesicles (sEVs) play a key role in intercellular communication. Cargo molecules carried by sEVs may affect the phenotype and function of recipient cells. Epithelial cancer cell-derived sEVs, particularly those enriched in CD151 or tetraspanin8 (TSPAN8) and associated integrins, promote tumour progression. The mechanism of binding and modulation of sEVs to recipient cells remains elusive. Here, we used genetically engineered breast cancer cells to derive TSPAN8-enriched sEVs and evaluated the impact of TSPAN8 on target cell membrane's diffusion and transport properties. The single-particle tracking technique showed that TSPAN8 significantly promoted sEV binding via confined diffusion. Functional assays indicated that the transgenic TSPAN8-sEV cargo increased cancer cell motility and epithelial-mesenchymal transition (EMT). In vivo, transgenic TSPAN8-sEV promoted uptake of sEVs in the liver, lung, and spleen. We concluded that TSPAN8 encourages the sEV-target cell interaction via forced confined diffusion and significantly increases cell motility. Therefore, TSPAN8-sEV may serve as an important direct or indirect therapeutic target.

Mesenchymal stromal cells enhance self-assembly of a HUVEC tubular network through uPA-uPAR/VEGFR2/integrin/NOTCH crosstalk

Endothelial cells (ECs) degrade the extracellular matrix of vessel walls and contact surrounding cells to facilitate migration during angiogenesis, leading to formation of an EC-tubular network (ETN). Mesenchymal stromal cells (MSC) support ETN formation when co-cultured with ECs, but the mechanism is incompletely understood. We examined the role of the urokinase-type plasminogen activator (uPA) system, i.e. the serine protease uPA, its inhibitor PAI-1, receptor uPAR/CD87, clearance by the low-density lipoprotein receptor-related protein (LRP1) and their molecular partners, in the formation of ETNs supported by adipose tissue-derived MSC. Co-culture of human umbilical vein ECs (HUVEC) with MSC increased mRNA expression levels of uPAR, MMP14, VEGFR2, TGFβ1, integrin β₃ and Notch pathway components (Notch1 receptor and ligands: Dll1, Dll4, Jag1) in HUVECs and uPA, uPAR, TGFβ1, integrin β₃, Jag1, Notch3 receptor in MSC. Inhibition at several steps in the activation process indicates that uPA, uPAR and LRP1 cross-talk with α_v-integrins, VEGFR2 and Notch receptors/ligands to mediate ETN formation in HUVEC-MSC co-culture. The urokinase system mediates ETN formation through the coordinated action of uPAR, uPA's catalytic activity, its binding to uPAR and its nuclear translocation. These studies identify potential targets to help control aberrant angiogenesis with minimal impact on healthy vasculature.

β-elemene inhibits non-small cell lung cancer cell migration and invasion by inactivating the FAK-Src pathway

Despite sustained effort, the prognosis of lung cancer remains poor and the therapeutic responses are limited. Cell movement ability is a prerequisite for lung cancer metastasis, which involves focal adhesion kinase (FAK)-mediated cell migration and invasion via complex formation with Src. Hence, FAK-Src signaling might be an effective target for anti-cancer treatment. β-elemene, the major component of elemene extracted from Curcuma Rhizoma, exhibits broad-spectrum anti-tumor properties. However, the role of β-elemene in lung cancer cell motility and its possible mechanism remain unknown. Herein, the role of β-elemene in the migration and invasion of two non-small cell lung cancer (NSCLC) cell lines was investigated by performing wound-healing and Transwell assays. The mRNA expression levels of genes associated with motility, including RhoA, Rac1, Cac42, matrix metalloprotease (MMP)2 and MMP9, were examined by reverse transcription-quantitative polymerase chain reaction. To determine whether β-elemene acts through FAK-Src signaling, western blotting was performed and the levels of phosphorylated FAK and Src were detected. The results indicated that β-elemene inhibited the migration and invasion of A549 and NCI-H1299 (H1299) cells, while the motility-associated genes were de-regulated following exposure to β-elemene. Furthermore, β-elemene decreased the activity of FAK and Src. Overall, these results suggest that β-elemene potentially inhibits NSCLC through FAK-Src signaling.

Characteristics of TIMP1, CD63, and β1-Integrin and the Functional Impact of Their Interaction in Cancer

Tissue Inhibitor of Metalloproteases 1, also known as TIMP-1, is named for its well-established function of inhibiting the proteolytic activity of matrix metalloproteases. Given this function, many studies were carried out to verify if TIMP-1 was able to interrupt processes such as tumor cell invasion and metastasis. In contrast, many studies have shown that TIMP-1 expression is increased in several types of tumors, and this increase was correlated with a poor prognosis and lower survival in cancer patients. Later, it was shown that TIMP-1 is also able to modulate cell behavior through the induction of signaling pathways involved in cell growth, proliferation, and survival. The mechanisms involved in the regulation of the pleiotropic functions of TIMP-1 are still poorly understood. Thus, this review aimed to present literature data that show its ability to form a membrane complex with CD63 and β1-integrin, and point to N-glycosylation as a potential regulatory mechanism of the functions exerted by TIMP-1. This article reviewed the characteristics and functions performed individually by TIMP1, CD63, and β1-integrin, the roles of the TIMP-1/CD63/β1-integrin complex, both in a physiological context and in cancer, and the regulatory mechanisms involved in its assembly.

FGF9/FGFR1 promotes cell proliferation, epithelial-mesenchymal transition, M2 macrophage infiltration and liver metastasis of lung cancer

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FGF9 induced cell proliferation, EMT, migration, and invasion of mouse Lewis lung cancer (LLC) cells, in vitro.

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FGF9 interacted with FGFR1 and activated FAK, AKT, and ERK/MAPK signal pathways, induced the expression of EMT key proteins (N-cadherin, vimentin, snail, MMP2, MMP3 and MMP13) and reduced the expression of E-cadherin.

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FGF9 promoted liver metastasis of subcutaneous inoculated LLC tumor with tumor growth, angiogenesis, EMT and M2-macrophage infiltration in the tumor microenvironment.

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The FGF9/LLC syngeneic animal model provides a useful tool for the mechanism studies of liver metastasis which is the worst prognostic factor for lung cancer patients with distant organ metastasis.

Fibroblast growth factors 9 (FGF9) modulates cell proliferation, differentiation and motility for development and repair in normal cells. Abnormal activation of FGF9 signaling is associated with tumor progression in many cancers. Also, FGF9 may be an unfavorable prognostic indicator for non-small cell lung cancer patients. However, the effects and mechanisms of FGF9 in lung cancer remain elusive. In this study, we investigated the FGF9-induced effects and signal activation profiles in mouse Lewis lung carcinoma (LLC) in vitro and in vivo. Our results demonstrated that FGF9 significantly induced cell proliferation and epithelial-to-mesenchymal transition (EMT) phenomena (migration and invasion) in LLC cells. Mechanism-wise, FGF9 interacted with FGFR1 and activated FAK, AKT, and ERK/MAPK signal pathways, induced the expression of EMT key proteins (N-cadherin, vimentin, snail, MMP2, MMP3 and MMP13), and reduced the expression of E-cadherin. Moreover, in the allograft mouse model, intratumor injection of FGF9 to LLC-tumor bearing C57BL/6 mice enhanced LLC tumor growth which were the results of increased Ki67 expression and decreased cleaved caspase-3 expression compared to control groups. Furthermore, we have a novel finding that FGF9 promoted liver metastasis of subcutaneous inoculated LLC tumor with angiogenesis, EMT and M2-macrophage infiltration in the tumor microenvironment. In conclusion, FGF9 activated FAK, AKT, and ERK signaling through FGFR1 with induction of EMT to stimulate LLC tumorigenesis and hepatic metastasis. This novel FGF9/LLC allograft animal model may therefore be useful to study the mechanism of liver metastasis which is the worst prognostic factor for lung cancer patients with distant organ metastasis.

Construction of a Single-Atom Nanozyme for Enhanced Chemodynamic Therapy and Chemotherapy

To fulfill the demand of precision and personalized medicine, single-atom catalysts (SACs) have emerged as a frontier in biomedical fields due to enzyme-mimic catalysis. Herein, we present a biocompatible and versatile nanoagent consisting of single-atom iron-containing nanoparticles (SAF NPs), DOX and A549 cell membrane (CM). The designed porous iron-based SACs originally served as a drug-carrying nanoplatform to release DOX selectively in a tumor microenvironment (TME) for chemotherapy (CT) due to their high loading capacity (155 %) for DOX; this signifies that SACs are promising candidates for universal cargo delivery. Besides, the designed single-atom nanoagent can perform like peroxidase, which effectively triggers an in situ tumor-specific Fenton reaction to generate abundant toxic hydroxyl radicals (⋅OH) selectively in the acidic TME for chemodynamic therapy (CDT). With the combination of CDT and CT, the constructed SAF NPs@DOX@CM nanoagent demonstrates better in vivo therapeutic performance than single-pathway therapy. In the meantime, after modification with CM, SAF NPs@DOX@CM can achieve homologous binding to target tumor tissues and avoid early clearance. This study presents a type of multifunctional SACs for enhanced cancer treatment via the capacity of a drug carrier combined with the enzymatic therapies of single-atom catalytic sites.

Mesenchymal stem cells in glioblastoma therapy and progression: How one cell does it all

Mesenchymal stem cells (MSCs) are among the most investigated and applied somatic stem cells in experimental therapies for the regeneration of damaged tissues. Moreover, as it was recently postulated, MSCs may demonstrate anti-tumor properties. Glioblastoma (GBM) is a grade IV central nervous system tumor with no available effective therapy and an inevitably fatal prognosis. Experimental studies utilizing MSCs in GBM treatment resulted in numerous controversies. Native MSCs were shown to exert anti-GBM activity by controlling angiogenesis, regulating cell cycle, and inducing apoptosis. They also were used as sensitizing factors and vehicles delivering various anti-cancer compounds. On the other hand, some experiments revealed significant risks related to MSC-based therapies for GBM, such as enhancement of tumor cell proliferation, invasion, and aggressiveness. The following review elaborates on all mentioned contradictory data and provides a realistic, current clinical perspective on MSCs' potential in GBM treatment.

Stromal Cell-Contact Dependent PI3K and APRIL Induced NF-κB Signaling Prevent Mitochondrial- and ER Stress Induced Death of Memory Plasma Cells

The persistence of long-lived memory plasma cells in the bone marrow depends on survival factors available in the bone marrow, which are provided in niches organized by stromal cells. Using an ex vivo system in which we supply the known survival signals, direct cell contact to stromal cells, and the soluble cytokine a proliferation-inducing ligand (APRIL), we have elucidated the critical signaling pathways required for the survival of long-lived plasma cells. Integrin-mediated contact of bone marrow plasma cells with stromal cells activates the phosphatidylinositol 3-kinase (PI3K) signaling pathway, leading to critical inactivation of Forkhead-Box-Protein O1/3 (FoxO1/3) and preventing the activation of mitochondrial stress-associated effector caspases 3 and 7. Accordingly, inhibition of PI3K signaling in vivo ablates bone marrow plasma cells. APRIL signaling, by the nuclear factor κB (NF-κB) pathway, blocks activation of the endoplasmic-reticulum-stress-associated initiator caspase 12. Thus, stromal-cell-contact-induced PI3K and APRIL-induced NF-κB signaling provide the necessary and complementary signals to maintain bone marrow memory plasma cells.

S-Nitrosylation in Tumor Microenvironment

S-nitrosylation is a selective and reversible post-translational modification of protein thiols by nitric oxide (NO), which is a bioactive signaling molecule, to exert a variety of effects. These effects include the modulation of protein conformation, activity, stability, and protein-protein interactions. S-nitrosylation plays a central role in propagating NO signals within a cell, tissue, and tissue microenvironment, as the nitrosyl moiety can rapidly be transferred from one protein to another upon contact. This modification has also been reported to confer either tumor-suppressing or tumor-promoting effects and is portrayed as a process involved in every stage of cancer progression. In particular, S-nitrosylation has recently been found as an essential regulator of the tumor microenvironment (TME), the environment around a tumor governing the disease pathogenesis. This review aims to outline the effects of S-nitrosylation on different resident cells in the TME and the diverse outcomes in a context-dependent manner. Furthermore, we will discuss the therapeutic potentials of modulating S-nitrosylation levels in tumors.

Regulators and signalling in insect antimicrobial innate immunity: Functional molecules and cellular pathways

Insects possess an immune system that protects them from attacks by various pathogenic microorganisms that would otherwise threaten their survival. Immune mechanisms may deal directly with the pathogens by eliminating them from the host organism or disarm them by suppressing the synthesis of toxins and virulence factors that promote the invasion and destructive action of the intruder within the host. Insects have been established as outstanding models for studying immune system regulation because innate immunity can be explored as an integrated system at the level of the whole organism. Innate immunity in insects consists of basal immunity that controls the constitutive synthesis of effector molecules such as antimicrobial peptides, and inducible immunity that is activated after detection of a microbe or its product(s). Activation and coordination of innate immune defenses in insects involve evolutionary conserved immune factors. Previous research in insects has led to the identification and characterization of distinct immune signalling pathways that modulate the response to microbial infections. This work has not only advanced the field of insect immunology, but it has also rekindled interest in the innate immune system of mammals. Here we review the current knowledge on key molecular components of insect immunity and discuss the opportunities they present for confronting infectious diseases in humans.

Exploiting S-nitrosylation for cancer therapy: facts and perspectives

S-nitrosylation, the post-translational modification of cysteines by nitric oxide, has been implicated in several cellular processes and tissue homeostasis. As a result, alterations in the mechanisms controlling the levels of S-nitrosylated proteins have been found in pathological states. In the last few years, a role in cancer has been proposed, supported by the evidence that various oncoproteins undergo gain- or loss-of-function modifications upon S-nitrosylation. Here, we aim at providing insight into the current knowledge about the role of S-nitrosylation in different aspects of cancer biology and report the main anticancer strategies based on: (i) reducing S-nitrosylation-mediated oncogenic effects, (ii) boosting S-nitrosylation to stimulate cell death, (iii) exploiting S-nitrosylation through synthetic lethality.

Heterogeneous Glioma Cell Invasion Under Interstitial Flow Depending on Their Differentiation Status

Glioblastoma (GBM) is the most common and lethal type of malignant brain tumor. A deeper mechanistic understanding of the invasion of heterogeneous GBM cell populations is crucial to develop therapeutic strategies. A key regulator of GBM cell invasion is interstitial flow. However, the effect of an interstitial flow on the invasion of heterogeneous GBM cell populations composed of glioma initiating cells (GICs) and relatively differentiated progeny cells remains unclear. In the present study, we investigated how GICs invade three-dimensional (3D) hydrogels in response to an interstitial flow with respect to their differentiation status. Microfluidic culture systems were used to apply an interstitial flow to the cells migrating from the cell aggregates into the 3D hydrogel. Phase-contrast microscopy revealed that the invasion and protrusion formation of the GICs in differentiated cell conditions were significantly enhanced by a forward interstitial flow, whose direction was the same as that of the cell invasion, whereas those in stem cell conditions were not enhanced by the interstitial flow. The mechanism of flow-induced invasion was further investigated by focusing on differentiated cell conditions. Immunofluorescence images revealed that the expression of cell-extracellular matrix adhesion-associated molecules, such as integrin β1, focal adhesion kinase, and phosphorylated Src, was upregulated in forward interstitial flow conditions. We then confirmed that cell invasion and protrusion formation were significantly inhibited by PP2, a Src inhibitor. Finally, we observed that the flow-induced cell invasion was preceded by nestin-positive immature GICs at the invasion front and followed by tubulin β3-positive differentiated cells. Our findings provide insights into the development of novel therapeutic strategies to inhibit flow-induced glioma invasion. Impact statement A mechanistic understanding of heterogeneous glioblastoma cell invasion is crucial for developing therapeutic strategies. We observed that the invasion and protrusion formation of glioma initiating cells (GICs) were significantly enhanced by forward interstitial flow in differentiated cell conditions. The expression of integrin β1, focal adhesion kinase, and phosphorylated Src was upregulated, and the flow-induced invasion was significantly inhibited by a Src inhibitor. The flow-induced heterogeneous cell invasion was preceded by nestin-positive GICs at the invasion front and followed by tubulin β3-positive differentiated cells. Our findings provide insights into the development of novel therapeutic strategies to inhibit flow-induced glioma invasion.

Regulation of Fibroblast Cell Polarity by Src Tyrosine Kinase

Src protein tyrosine kinases (SFKs) are a family of nonreceptor tyrosine kinases that are localized beneath the plasma membrane and are activated during cell adhesion, migration, and elongation. Due to their involvement in the activation of signal transduction cascades, SFKs have been suggested to play important roles in the determination of cell polarity during cell extension and elongation. However, the mechanism underlying Src-mediated polarity formation remains unclear. The present study was performed to investigate the mechanisms underlying Src-induced cell polarity formation and cell elongation using Src knockout fibroblasts (SYFs) together with an inhibitor of Src. Normal and Src knockout fibroblasts were also transfected with a wild-type c-Src, dominant negative c-Src, or constitutively active c-Src gene to analyze the changes in cell morphology. SYF cells cultured on a glass substrate elongated symmetrically into spindle-shaped cells, with the formation of focal adhesions at both ends of the cells. When normal fibroblasts were treated with Src Inhibitor No. 5, a selective inhibitor of Src tyrosine kinases, they elongated into symmetrical spindle-shaped cells, similar to SYF cells. These results suggest that cell polarity during extension and elongation may be regulated by SFKs and that the expression and regulation of Src are important for the formation of polarity during cell elongation.

Kahweol, a Diterpenoid Molecule, Inhibits CTGF-Dependent Synthetic Phenotype Switching and Migration in Vascular Smooth Muscle Cells

Vascular smooth muscle cell (VSMC) phenotype switching from contractile to synthetic is essential for proliferation and migration in vascular pathophysiology. Connective tissue growth factor (CTGF) is a matricellular protein involved in cell adhesion, migration, and proliferation. Kahweol, a diterpene molecule in arabica coffee beans, has been reported to have anti-inflammatory, antiproliferative, and apoptotic effects in many cells. However, in VSMCs, the effects of kahweol on CTGF activities have not been investigated. Thus, in this study, the effects and associated mechanisms of kahweol in CTGF-dependent phenotype switching and migration in VSMCs were examined. Experiments were performed on primary rat aortic smooth muscle cells and a rat VSMC line, A7r5. Western blot analysis was used to determine the protein levels. The mRNA levels of synthetic markers were measured by qRT-PCR. Migration of VSMCs was evaluated by wound healing and transwell assays. Kahweol reduced the angiotensin II (Ang II)-induced CTGF expression. Further, kahweol inhibited expressions of synthetic phenotype markers of VSMC. The kahweol-reduced synthetic marker protein levels were reversed by the administration of rCTGF. However, expressions of contractile phenotype markers of VSMC were not affected. Kahweol suppressed Ang II-stimulated VSMC migration. Moreover, kahweol downregulated Ang II-induced p-FAK, p-Erk, and Yes-associated protein (YAP) protein expressions. Taken together, in Ang II-stimulated VSMCs, kahweol inhibited CTGF-dependent synthetic phenotype switching and migration, with focal adhesion kinase (FAK), Erk, and YAP involved in the underlying mechanisms of the kahweol effects. These results suggest that kahweol has a potential as a therapeutic agent to inhibit CTGF, which is a molecular target in sclerogenic vascular disease.

SRC Signaling in Cancer and Tumor Microenvironment

Pioneering experiments performed by Harold Varmus and Mike Bishop in 1976 led to one of the most influential discoveries in cancer research and identified the first cancer-causing oncogene called Src. Later experimental and clinical evidence suggested that Src kinase plays a significant role in promoting tumor growth and progression and its activity is associated with poor patient survival. Thus, several Src inhibitors were developed and approved by FDA for treatment of cancer patients. Tumor microenvironment (TME) is a highly complex and dynamic milieu where significant cross-talk occurs between cancer cells and TME components, which consist of tumor-associated macrophages, fibroblasts, and other immune and vascular cells. Growth factors and chemokines activate multiple signaling cascades in TME and induce multiple kinases and pathways, including Src, leading to tumor growth, invasion/metastasis, angiogenesis, drug resistance, and progression. Here, we will systemically evaluate recent findings regarding regulation of Src and significance of targeting Src in cancer therapy.

Cx43 and the Actin Cytoskeleton: Novel Roles and Implications for Cell-Cell Junction-Based Barrier Function Regulation

Barrier function is a vital homeostatic mechanism employed by epithelial and endothelial tissue. Diseases across a wide range of tissue types involve dynamic changes in transcellular junctional complexes and the actin cytoskeleton in the regulation of substance exchange across tissue compartments. In this review, we focus on the contribution of the gap junction protein, Cx43, to the biophysical and biochemical regulation of barrier function. First, we introduce the structure and canonical channel-dependent functions of Cx43. Second, we define barrier function and examine the key molecular structures fundamental to its regulation. Third, we survey the literature on the channel-dependent roles of connexins in barrier function, with an emphasis on the role of Cx43 and the actin cytoskeleton. Lastly, we discuss findings on the channel-independent roles of Cx43 in its associations with the actin cytoskeleton and focal adhesion structures highlighted by PI3K signaling, in the potential modulation of cellular barriers. Mounting evidence of crosstalk between connexins, the cytoskeleton, focal adhesion complexes, and junctional structures has led to a growing appreciation of how barrier-modulating mechanisms may work together to effect solute and cellular flux across tissue boundaries. This new understanding could translate into improved therapeutic outcomes in the treatment of barrier-associated diseases.

The Function of Oncogene B-Cell Lymphoma 6 in the Regulation of the Migration and Invasion of Trophoblastic Cells

Human placentation is a highly invasive process. Deficiency in the invasiveness of trophoblasts is associated with a spectrum of gestational diseases, such as preeclampsia (PE). The oncogene B-cell lymphoma 6 (BCL6) is involved in the migration and invasion of various malignant cells. Intriguingly, its expression is deregulated in preeclamptic placentas. We have reported that BCL6 is required for the proliferation, survival, fusion, and syncytialization of trophoblasts. In the present work, we show that the inhibition of BCL6, either by its gene silencing or by using specific small molecule inhibitors, impairs the migration and invasion of trophoblastic cells, by reducing cell adhesion and compromising the dynamics of the actin cytoskeleton. Moreover, the suppression of BCL6 weakens the signals of the phosphorylated focal adhesion kinase, Akt/protein kinase B, and extracellular regulated kinase 1/2, accompanied by more stationary, but less migratory, cells. Interestingly, transcriptomic analyses reveal that a small interfering RNA-induced reduction of BCL6 decreases the levels of numerous genes, such as p21 activated kinase 1, myosin light chain kinase, and gamma actin related to cell adhesion, actin dynamics, and cell migration. These data suggest BCL6 as a crucial player in the migration and invasion of trophoblasts in the early stages of placental development through the regulation of various genes associated with the migratory machinery.

In Full Force. Mechanotransduction and Morphogenesis during Homeostasis and Tissue Regeneration

The interactions of form and function have been the focus of numerous studies in the context of development and more recently regeneration. Our understanding on how cells, tissues and organs sense and interpret external cues, such as mechanical forces, is becoming deeper as novel techniques in imaging are applied and the relevant signaling pathways emerge. These cellular responses can be found from bacteria to all multicellular organisms such as plants and animals. In this review, we focus on hemodynamic flow and endothelial shear stress during cardiovascular development and regeneration, where the interactions of morphogenesis and proper function are more prominent. In addition, we address the recent literature on the role of extracellular matrix and fibrotic response during tissue repair and regeneration. Finally, we refer to examples where the integration of multi-disciplinary approaches to understand the biomechanics of cellular responses could be utilized in novel medical applications.