Actin-tethered junctional complexes in angiogenesis and lymphangiogenesis in association with vascular endothelial growth factor

Phytoconstituent-derived zingerone nanoparticles disrupt the cell adhesion mechanism and suppress cell motility in melanoma B16F10 cells

Combining phytochemicals and nanotechnology to improve the unfavorable innate properties of phytochemicals and develop them into potent nanomedicines to enhance antitumor efficacy has become a novel strategy for cancer chemoprevention. Melanoma is the most aggressive, metastatic, and deadly disease of the primary cutaneous neoplasms. In this study, we fabricated phytoconstituent-derived zingerone nanoparticles (NPs) and validated their effects on cell adhesion and motility in melanoma B16F10 cells. Our data indicated that zingerone NPs significantly induced cytotoxicity and anti-colony formation and inhibited cell migration and invasion. Moreover, zingerone NPs dramatically interfered with the cytoskeletal reorganization and markedly delayed the period of cell adhesion. Our results also revealed that zingerone NPs-mediated downregulation of MMPs (matrix metalloproteinases) activity is associated with inhibiting cell adhesion and motility. We further evaluated the effects of zingerone NPs on Src/FAK /Paxillin signaling, our data showed that zingerone NPs significantly inhibited the protein activities of Src, FAK, and Paxillin, indicating that they play important roles in zingerone NP-mediated anti-motility and anti-invasion in melanoma cells. Accordingly, the phytoconstituent-zingerone NPs can strengthen the inhibition of tumor growth, invasion, and metastasis in malignant melanoma. Altogether, these multi-pharmacological benefits of zingerone NPs will effectively achieve the purpose of melanoma prevention and invasion inhibition.

Nectins and Nectin-like molecules drive vascular development and barrier function

Angiogenesis, barriergenesis, and immune cell migration are all key physiological events that are dependent on the functional characteristics of the vascular endothelium. The protein family of Nectins and Nectin-like molecules (Necls) is a group of cell adhesion molecules that are widely expressed by different endothelial cell types. The family includes four Nectins (Nectin-1 to -4) and five Necls (Necl-1 to -5) that either interact with each other by forming homo- and heterotypical interactions or bind to ligands expressed within the immune system. Nectin and Necl proteins are mainly described to play a role in cancer immunology and in the development of the nervous system. However, Nectins and Necls are underestimated players in the formation of blood vessels, their barrier properties, and in guiding transendothelial migration of leukocytes. This review summarizes their role in supporting the endothelial barrier through their function in angiogenesis, cell-cell junction formation, and immune cell migration. In addition, this review provides a detailed overview of the expression patterns of Nectins and Necls in the vascular endothelium.

Wound Healing from an Actin Cytoskeletal Perspective

Wound healing requires a complex cascade of highly controlled and conserved cellular and molecular processes. These involve numerous cell types and extracellular matrix molecules regulated by the actin cytoskeleton. This microscopic network of filaments is present within the cytoplasm of all cells and provides the shape and mechanical support required for cell movement and proliferation. Here, an overview of the processes of wound healing are described from the perspective of the cell in relation to the actin cytoskeleton. Key points of discussion include the role of actin, its binding proteins, signaling pathways, and events that play significant roles in the phases of wound healing. The identification of cytoskeletal targets that can be used to manipulate and improve wound healing is included as an emerging area of focus that may inform future therapeutic approaches to improve healing of complex wounds.

PI3K/AKT Signaling Tips the Balance of Cytoskeletal Forces for Cancer Progression

The PI3K/AKT signaling pathway plays essential roles in multiple cellular processes, which include cell growth, survival, metabolism, and motility. In response to internal and external stimuli, the PI3K/AKT signaling pathway co-opts other signaling pathways, cellular components, and cytoskeletal proteins to reshape individual cells. The cytoskeletal network comprises three main components, which are namely the microfilaments, microtubules, and intermediate filaments. Collectively, they are essential for many fundamental structures and cellular processes. In cancer, aberrant activation of the PI3K/AKT signaling cascade and alteration of cytoskeletal structures have been observed to be highly prevalent, and eventually contribute to many cancer hallmarks. Due to their critical roles in tumor progression, pharmacological agents targeting PI3K/AKT, along with cytoskeletal components, have been developed for better intervention strategies against cancer. In our review, we first discuss existing evidence in-depth and then build on recent advances to propose new directions for therapeutic intervention.

Possible Contributions of Nongenomic Actions of Thyroid Hormones to the Vasculopathic Complex of COVID-19 Infection

BACKGROUND

Integrin αvβ3 is a cell membrane structural protein whose extracellular domain contains a receptor for L-thyroxine (T4). The integrin is expressed in rapidly dividing cells and its internalization is prompted by T4. The protein binds viruses and we have raised the possibility elsewhere that action of free T4 (FT4)-when he latter is increased in the nonthyroidal illness syndrome (NTIS) known to complicate COVID-19 infecction-may enhance cellular uptke of SARS-CoV-2 and its receptor.

OBJECTIVE

Because T4 also acts nongenomically via the integrin to promote platelet aggregation and angiogenesis, we suggest here that T4 may contribute to the coagulopathy and endothelial abnormalities that can develop in COVID-19 infections, particularly when the lung is primary affected.

DISCUSSION AND CONCLUSIONS

Elevated FT4 has been described in the NTIS of COVID-19 patients and may be associated with increased illness severity, but the finding of FT4 elevation is inconsistent in the NTIS literature. Circulating 3,5',3'-triiodo-L-thyronine (reverse T3, rT3) are frequently elevated in NTIS. Thought to be biologically inactive, rT3in fact stimulates cancer cell proliferation via avb3 and also may increase actin polymerization. We propose here that rT3 in the NTIS complicating systemic COVIF-19 infection may support coagulation and disordered blood vessel formation via actin polymerization.

Cytoskeletal Dynamics in Epithelial-Mesenchymal Transition: Insights into Therapeutic Targets for Cancer Metastasis

In cancer cells, a vital cellular process during metastasis is the transformation of epithelial cells towards motile mesenchymal cells called the epithelial to mesenchymal transition (EMT). The cytoskeleton is an active network of three intracellular filaments: actin cytoskeleton, microtubules, and intermediate filaments. These filaments play a central role in the structural design and cell behavior and are necessary for EMT. During EMT, epithelial cells undergo a cellular transformation as manifested by cell elongation, migration, and invasion, coordinated by actin cytoskeleton reorganization. The actin cytoskeleton is an extremely dynamic structure, controlled by a balance of assembly and disassembly of actin filaments. Actin-binding proteins regulate the process of actin polymerization and depolymerization. Microtubule reorganization also plays an important role in cell migration and polarization. Intermediate filaments are rearranged, switching to a vimentin-rich network, and this protein is used as a marker for a mesenchymal cell. Hence, targeting EMT by regulating the activities of their key components may be a potential solution to metastasis. This review summarizes the research done on the physiological functions of the cytoskeleton, its role in the EMT process, and its effect on multidrug-resistant (MDR) cancer cells-highlight some future perspectives in cancer therapy by targeting cytoskeleton.

Autoregulatory "Multitasking" at Endothelial Cell Junctions by Junction-Associated Intermittent Lamellipodia Controls Barrier Properties

Vascular endothelial cell (EC) junctions are key structures controlling tissue homeostasis in physiology. In the last three decades, excellent studies have addressed many aspects of this complex and highly dynamic regulation, including cell signaling, remodeling processes of the proteins of tight junctions, adherens junctions, and gap junctions, the cytoskeleton, and post-transcriptional modifications, transcriptional activation, and gene silencing. In this dynamic process, vascular endothelial cadherin (VE-cadherin) provides the core structure of EC junctions mediating the physical adhesion of cells as well as the control of barrier function and monolayer integrity via remodeling processes, regulation of protein expression and post-translational modifications. In recent years, research teams have documented locally restricted dynamics of EC junctions in which actin-driven protrusions in plasma membranes play a central role. In this regard, our research group showed that the dynamics of VE-cadherin is driven by small (1-5 μm) actin-mediated protrusions in plasma membranes that, due to this specific function, were named "junction-associated intermittent lamellipodia" (JAIL). JAIL form at overlapping, adjacent cells, and exactly at this site new VE-cadherin interactions occur, leading to new VE-cadherin adhesion sites, a process that restores weak or lost VE-cadherin adhesion. Mechanistically, JAIL formation occurs locally restricted (1-5 μm) and underlies autoregulation in which the local VE-cadherin concentration is an important parameter. A decrease in the local concentration of VE-cadherin stimulates JAIL formation, whereas an increase in the concentration of VE-cadherin blocks it. JAIL mediated VE-cadherin remodeling at the subjunctional level have been shown to be of crucial importance in angiogenesis, wound healing, and changes in permeability during inflammation. The concept of subjunctional regulation of EC junctions is strongly supported by permeability assays, which can be employed to quantify actin-driven subjunctional changes. In this brief review, we summarize and discuss the current knowledge and concepts of subjunctional regulation in the endothelium.

Polyisoprenylated Cysteinyl Amide Inhibitors: A Novel Approach to Controlling Cancers with Hyperactive Growth Signaling

Aberrant activation of monomeric G-protein signaling pathways drives some of the most aggressive cancers. Suppressing these hyperactivities has been the focus of efforts to obtain targeted therapies. Polyisoprenylated methylated protein methyl esterase (PMPMEase) is overexpressed in various cancers. Its inhibition induces the death of cancer cells that harbor the constitutively active K-Ras proteins. Furthermore, the viability of cancer cells driven by factors upstream of K-Ras, such as overexpressed growth factors and their receptors or the mutationally-activated receptors, is also susceptible to PMPMEase inhibition. Polyisoprenylated cysteinyl amide inhibitors (PCAIs) were thus designed to target cancers with hyperactive signaling pathways involving the G-proteins. The PCAIs were, however, poor inhibitors of PMPMEase, with Ki values ranging from 3.7 to 20 μM. On the other hand, they inhibited cell viability, proliferation, colony formation, induced apoptosis in cells with mutant K-Ras and inhibited cell migration and invasion with EC50 values of 1 to 3 μM. HUVEC tube formation was inhibited at submicromolar concentrations through their disruption of actin filament organization. At the molecular level, the PCAIs at 2 to 5 μM depleted monomeric G-proteins such as K-Ras, RhoA, Cdc42 and Rac1. The PCAIs also deplete vinculin and fascin that are involved in actin organization and function while disrupting vinculin punctates in the process. These demonstrate a polyisoprenylation-dependent mechanism that explains the observed PCAIs' inhibition of the proliferative, invasive and angiogenic processes that promote both tumor growth and metastasis.

Fucoxanthin inhibits tumour-related lymphangiogenesis and growth of breast cancer

Tumour lymphangiogenesis plays an important role in promoting the growth and lymphatic metastasis of tumours. The process is associated with cell proliferation, migration and tube-like structure formation in lymphatic endothelial cells (LEC), but no antilymphangiogenic agent is currently used in clinical practice. Fucoxanthin is a material found in brown algae that holds promise in the context of drug development. Fucoxanthin is a carotenoid with variety of pharmacological functions, including antitumour and anti-inflammatory effects. The ability of fucoxanthin to inhibit lymphangiogenesis remains unclear. The results of experiments performed as part of this study show that fucoxanthin, extracted from Undaria pinnatifida (Wakame), inhibits proliferation, migration and formation of tube-like structures in human LEC (HLEC). In this study, fucoxanthin also suppressed the malignant phenotype in human breast cancer MDA-MB-231 cells and decreased tumour-induced lymphangiogenesis when used in combination with a conditional medium culture system. Fucoxanthin significantly decreased levels of vascular endothelial growth factor (VEGF)-C, VEGF receptor-3, nuclear factor kappa B, phospho-Akt and phospho-PI3K in HLEC. Fucoxanthin also decreased micro-lymphatic vascular density (micro-LVD) in a MDA-MB-231 nude mouse model of breast cancer. These findings suggest that fucoxanthin inhibits tumour-induced lymphangiogenesis in vitro and in vivo, highlighting its potential use as an antilymphangiogenic agent for antitumour metastatic comprehensive therapy in patients with breast cancer.

Multiple Rap1 effectors control Epac1-mediated tightening of endothelial junctions

Epac1 and Rap1 mediate cAMP-induced tightening of endothelial junctions. We have previously found that one of the mechanisms is the inhibition of Rho-mediated tension in radial stress fibers by recruiting the RhoGAP ArhGAP29 in a complex containing the Rap1 effectors Rasip1 and Radil. However, other mechanisms have been proposed as well, most notably the induction of tension in circumferential actin cables by Cdc42 and its GEF FGD5. Here, we have investigated how Rap1 controls FGD5/Cdc42 and how this interconnects with Radil/Rasip1/ArhGAP29. Using endothelial barrier measurements, we show that Rho inhibition is not sufficient to explain the barrier stimulating effect of Rap1. Indeed, Cdc42-mediated tension is induced at cell-cell contacts upon Rap1 activation and this is required for endothelial barrier function. Depletion of potential Rap1 effectors identifies AF6 to mediate Rap1 enhanced tension and concomitant Rho-independent barrier function. When overexpressed in HEK293T cells, AF6 is found in a complex with FGD5 and Radil. From these results we conclude that Rap1 utilizes multiple pathways to control tightening of endothelial junctions, possibly through a multiprotein effector complex, in which AF6 functions to induce tension in circumferential actin cables.

Rap1 in endothelial biology

PURPOSE OF REVIEW

Ubiquitously-expressed small GTPase Rap1 is a key modulator of integrin- and cadherin-regulated processes. In endothelium, Rap1 promotes angiogenesis and endothelial barrier function, acting downstream from cAMP-activated Rap1GEF, Epac. Recent in-vivo studies in mouse models have provided more information about the physiological role of Rap1 in vessel development and after birth under normal and pathologic conditions. Important molecular details of dynamic regulation of endothelial barrier are uncovered.

RECENT FINDINGS

Rap1 is not essential for initial vessel formation but is critical for vessel stabilization, as double knockout of the two Rap1 isoforms leads to hemorrhage and embryonic lethality. After development, Rap1 is not required for endothelial barrier maintenance but is critical for nitric oxide production and endothelial function. Radil and Afadin mediate Rap1 effects on endothelial barrier function by regulating connection with Rho GTPases, actomyosin cytoskeleton, and cell-cell adhesion receptors.

SUMMARY

Rap1 is critically required for nitric oxide release and normal endothelial function in vivo. Mechanistic studies lead to a novel paradigm of Rap1 as a critical regulator of endothelial cell shear stress responses and endothelial homeostasis. Increased understanding of molecular mechanisms underlying endothelial barrier regulation may identify novel pharmacological targets for retinopathies and conditions with altered endothelial barrier function or when increased endothelial barrier is desired.

Downregulation of ERRα inhibits angiogenesis in human umbilical vein endothelial cells through regulating VEGF production and PI3K/Akt/STAT3 signaling pathway

The human estrogen related receptor α (ERRα) is a pivotal regulator involved in energy homeostasis and mitochondrial biogenesis. It has been demonstrated that activation of ERRα in various breast cancer cells results in a significant increase of vascular endothelial growth factor (VEGF) mRNA and protein secretion. However, little is known about the relationship between ERRα and angiogenesis. Thus, the present study is aimed to investigate the effects and mechanism of ERRα suppression on the angiogenesis in human umbilical vein endothelial cells (HUVECs). Here we show that ERRα suppression powerfully inhibits proliferation, migration and capillary-like structures formation of HUVECs. Importantly, we demonstrate that these inhibitory effects are associated with the significantly reduced expression and production of VEGF. Results from further experiments using western blot and luciferase reporter assay exhibit that ERRα suppression inhibits hypoxia-inducible factor 1α (HIF-1α) expression, and phosphorylation of protein kinase B (Akt) and signal transducer and activator of transcription (STAT3) which up-regulated VEGF expression. In summary, we show that ERRα suppression inhibits angiogenesis in HUVECs and deserves further studies for application of rationale therapeutic target for patient with diseases related with aberrant angiogenesis.