Vascular endothelial-cadherin stimulates syndecan-1-coupled insulin-like growth factor-1 receptor and cross-talk between αVβ3 integrin and vascular endothelial growth factor receptor 2 at the onset of endothelial cell dissemination during angiogenesis

High Glucose Induces Oxidative Stress That Alters Glycocalyx Proteoglycan Levels in Primary Rat Retinal Microvascular Endothelial Cells and in Isolated Ophthalmic Arteries

Our purpose in this study was to identify the role played by oxidative stress in the changes to proteoglycans that occur under hyperglycemic conditions, using primary rat retinal microvascular endothelial cells (RRMEC) and cultured ophthalmic arteries. The cells and blood vessels obtained from rats were cultured in normal glucose (5.6 mM) and high glucose (25 mM) with or without N-acetylcysteine (NAC), an antioxidant. Intracellular oxidative stress was determined by measuring dihydroethidium (DHE) fluorescence and malondialdehyde (MDA)-modified protein levels. mRNA and protein levels were evaluated using quantitative real-time polymerase chain reaction and immunoblot, respectively. High glucose increased levels of glypican-1 mRNA and protein. The level of syndecan-1 mRNA also was increased, but its protein level was decreased, by high glucose. Evaluation of DHE and MDA showed that high glucose increased oxidative stress. These changes caused by high glucose were significantly reversed by NAC treatment. Matrix metalloproteinase-9 (MMP-9) levels, which increased under high glucose conditions, were suppressed by NAC treatment. Oxidative stress caused by hyperglycemia may be responsible for significant changes to the ocular endothelial glycocalyx.

Mesothelial cells with mesenchymal features enhance peritoneal dissemination by forming a protumorigenic microenvironment

Malignant ascites accompanied by peritoneal dissemination contain various factors and cell populations as well as cancer cells; however, how the tumor microenvironment is shaped in ascites remains unclear. Single-cell proteomic profiling and a comprehensive proteomic analysis are conducted to comprehensively characterize malignant ascites. Here, we find defects in immune effectors along with immunosuppressive cell accumulation in ascites of patients with gastric cancer (GC) and identify five distinct subpopulations of CD45(-)/EpCAM(-) cells. Mesothelial cells with mesenchymal features in CD45(-)/EpCAM(-) cells are the predominant source of chemokines involved in immunosuppressive myeloid cell (IMC) recruitment. Moreover, mesothelial-mesenchymal transition (MMT)-induced mesothelial cells strongly express extracellular matrix (ECM)-related genes, including tenascin-C (TNC), enhancing metastatic colonization. These findings highlight the definite roles of the mesenchymal cell population in the development of a protumorigenic microenvironment to promote peritoneal dissemination.

Inhibiting IGF1R-mediated Survival Signaling in Head and Neck Cancer with the Peptidomimetic SSTNIGF1R

Previous studies have shown that the type I IGFR (IGF1R) suppresses apoptosis when it is autoactivated by coupling its extracellular domain to a matrix adhesion receptor complex consisting of syndecan-1 (Sdc1) and αvβ3 or αvβ5 integrin. We now report that head and neck squamous cell carcinoma (HNSCC) relies on this receptor complex. Disruption of the complex in HNSCC cells in vitro with a peptide mimetic of the organizer site in Sdc1 (called SSTNIGF1R) inactivates IGF1R, even in the presence of IGF1, and relieves the suppression of apoptosis signal-regulating kinase-1 (ASK1), dramatically reducing tumor cell survival. Normal epithelial cells do not assemble this receptor complex, require IGF1 to activate the IGF1R, and are refractory to SSTNIGF1R. In vivo, SSTNIGF1R reduced the growth of patient-derived HNSCC tumors in immunodeficient mice by 85%-95%. IGF1R's assimilation into the matrix receptor complex, which is detected in these tumors using the proximity ligation assay (PLA), is quantitatively disrupted by SSTNIGF1R, coinciding with ASK1 activation. PLA also detects the IGF1R-containing receptor complex in the archival sections of tonsil carcinomas, whereas the adjacent benign epithelium is negative. Likewise, PLA screening of oropharyngeal and adenoid cystic tumor microarrays demonstrated that over 95% of the tumors contained this unique receptor complex with no detectable expression in benign tissue. These findings suggest that HNSCC upregulates and is highly dependent on IGF1R signaling via this adhesion receptor complex. Targeting this mechanism with novel therapeutics, including highly specific SSTNIGF1R, is likely to offer promising outcomes for patients with carcinoma.

Significance

A newly developed biomarker reveals upregulation of an antiapoptotic IGF1R-integrin-syndecan receptor complex in head and neck cancer and documents disruption of the complex in patient-derived tumor xenografts (PDX) treated with the inhibitor SSTNIGF1R. A corresponding blockade in PDX growth in the presence of this inhibitor demonstrates that therapies designed to target this mechanism will likely offer promising outcomes for patients with head and neck cancer.

CD138 Is Expressed in Different Entities of Salivary Gland Cancer and Their Lymph Node Metastases and Therefore Represents a Potential Therapeutic Target

Advanced salivary gland carcinomas (SGC) often lack therapeutic options. Agents targeting CD138 have recently shown promising results in clinical trials for multiple myeloma and a preclinical trial for triple-negative breast cancer. Immunohistochemistry for CD138 was performed for all patients who had undergone primary surgery for SGC with curative intent. Findings were validated using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging. Overall, 111 primary SGC and 13 lymph node metastases from salivary duct carcinomas (SaDu) were evaluated. CD138 expression was found in 60% of all SGC with differing expression across entities (p < 0.01). A mean of 25.2% of the tumor cells in mucoepidermoid carcinoma (MuEp) were positive, followed by epithelial-myoepithelial carcinoma (20.9%), acinic cell carcinoma (16.0%), and SaDu (15.2%). High-/intermediate-grade MuEp showed CD138 expression in a mean of 34.8% of tumor cells. For SaDu, lymph node metastases showed CD138 expression in a mean of 31.2% of tumor cells which correlated with CD138 expression in their primaries (p = 0.01; Spearman’s ρ = 0.71). MALDI-MS imaging confirmed the presence of the CD138 protein in SGC. No significant association was found between clinicopathological data, including progression-free survival (p = 0.50) and CD138 expression. CD138 is expressed in the cell membrane of different entities of SGC and SaDu lymph node metastases and therefore represents a potential target for CD138 targeting drugs.

Harnessing Human Papillomavirus’ Natural Tropism to Target Tumors

Human papillomaviruses (HPV) are small non-enveloped DNA tumor viruses established as the primary etiological agent for the development of cervical cancer. Decades of research have elucidated HPV’s primary attachment factor to be heparan sulfate proteoglycans (HSPG). Importantly, wounding and exposure of the epithelial basement membrane was found to be pivotal for efficient attachment and infection of HPV in vivo. Sulfation patterns on HSPG’s become modified at the site of wounds as they serve an important role promoting tissue healing, cell proliferation and neovascularization and it is these modifications recognized by HPV. Analogous HSPG modification patterns can be found on tumor cells as they too require the aforementioned processes to grow and metastasize. Although targeting tumor associated HSPG is not a novel concept, the use of HPV to target and treat tumors has only been realized in recent years. The work herein describes how decades of basic HPV research has culminated in the rational design of an HPV-based virus-like infrared light activated dye conjugate for the treatment of choroidal melanoma.

Plasma membrane proteoglycans syndecan-2 and syndecan-4 engage with EGFR and RON kinase to sustain carcinoma cell cycle progression

Epidermal growth factor receptor (EGFR) is a causal factor in carcinoma, yet many carcinoma patients are resistant to EGFR inhibitors. Potential insight into this resistance stems from prior work that showed EGFR in normal epithelial cells docks to the extracellular domain of the plasma membrane proteoglycan syndecan-4 (Sdc4) engaged with α3β1 and α6β4 integrins. We now report that this receptor complex is modified by the recruitment of syndecan-2 (Sdc2), the Recepteur d'Origine Nantais (RON) tyrosine kinase, and the cellular signaling mediator Abelson murine leukemia viral oncogene homolog 1 (ABL1) in triple-negative breast carcinoma and head and neck squamous cell carcinoma, where it contributes to EGFR kinase-independent proliferation. Treatment with a peptide mimetic of the EGFR docking site in the extracellular domain of Sdc4 (called SSTNEGFR) disrupts the entire complex and causes a rapid, global arrest of the cell cycle. Normal epithelial cells do not recruit these additional receptors to the adhesion mechanism and are not arrested by SSTNEGFR. Although EGFR docking with Sdc4 in the tumor cells is required, cell cycle progression does not depend on EGFR kinase. Instead, progression depends on RON kinase, activated by its incorporation into the complex. RON activates ABL1, which suppresses p38 mitogen-activated protein kinase and prevents a p38-mediated signal that would otherwise arrest the cell cycle. These findings add to the growing list of receptor tyrosine kinases that support tumorigenesis when activated by their association with syndecans at sites of matrix adhesion and identify new potential targets for cancer therapy.

Targeting Syndecan-1: New Opportunities in Cancer Therapy

Syndecan-1 (SDC1, CD138) is one of the heparan sulfate proteoglycans and is essential for maintaining normal cell morphology, interacting with extracellular and intracellular protein repertoire as well as mediating signaling transduction upon environmental stimuli. The critical role of SDC1 in promoting tumorigenesis and metastasis has been increasingly recognized in various cancer types, implying a promising potential of utilizing SDC1 as a novel target for cancer therapy. This review summarizes the current knowledge on SDC1 structure and functions, including its role in tumor biology. We also discuss the highlights and limitations of current SDC1-targeted therapies as well as the obstacles in developing new therapeutic methods, offering our perspective on the future directions to target SDC1 for cancer treatment.

The Role and Therapeutic Value of Syndecan-1 in Cancer Metastasis and Drug Resistance

Metastasis and relapse are major causes of cancer-related fatalities. The elucidation of relevant pathomechanisms and adoption of appropriate countermeasures are thus crucial for the development of clinical strategies that inhibit malignancy progression as well as metastasis. An integral component of the extracellular matrix, the type 1 transmembrane glycoprotein syndecan-1 (SDC-1) binds cytokines and growth factors involved in tumor microenvironment modulation. Alterations in its localization have been implicated in both cancer metastasis and drug resistance. In this review, available data regarding the structural characteristics, shedding process, and nuclear translocation of SDC-1 are detailed with the aim of highlighting strategies directly targeting SDC-1 as well as SDC-1-mediated carcinogenesis.

The Glypican-1/HGF/C-Met and Glypican-1/VEGF/VEGFR2 Ternary Complexes Regulate Hair Follicle Angiogenesis

The hair renewal involves changes in the morphology of the hair follicle and its micro-vascularization. In alopecia, the hair cycle is accelerated, resulting in the formation of thinner and shorter hair. In addition, alopecia is associated with a decrease in the micro-vascularization of the hair follicles. In this study, the role of glypicans (GPCs) was analyzed in the regulation of the angiogenesis of human dermal microvascular endothelial cells (HDMEC). The analysis of glypican gene expression showed that GPC1 is the major glypican expressed by human keratinocytes of outer root sheath (KORS), human hair follicle dermal papilla cells (HHFDPC) and HDMEC. KORS were demonstrated to secrete VEGF and HGF. The HDMEC pseudotube formation was induced by KORS conditioned media (KORS_CM). It was totally abrogated after GPC1 siRNA transfection of HDMEC. Moreover, when cleaved by phospholipase C (PLC), GPC1 promotes the proliferation of HDMEC. Finally, GPC1 was shown to interact directly with VEGFR2 or c-Met to regulate angiogenesis induced by the activation of these receptors. Altogether, these results showed that GPC1 is a key regulator of microvascular endothelial cell angiogenesis induced by VEGF and HGF secreted by KORS. Thus, GPC1 might constitute an interesting target to tackle alopecia in dermatology research.

The Glomerular Endothelium Restricts Albumin Filtration

Inflammatory activation and/or dysfunction of the glomerular endothelium triggers proteinuria in many systemic and localized vascular disorders. Among them are the thrombotic microangiopathies, many forms of glomerulonephritis, and acute inflammatory episodes like sepsis and COVID-19 illness. Another example is the chronic endothelial dysfunction that develops in cardiovascular disease and in metabolic disorders like diabetes. While the glomerular endothelium is a porous sieve that filters prodigious amounts of water and small solutes, it also bars the bulk of albumin and large plasma proteins from passing into the glomerular filtrate. This endothelial barrier function is ascribed predominantly to the endothelial glycocalyx with its endothelial surface layer, that together form a relatively thick, mucinous coat composed of glycosaminoglycans, proteoglycans, glycolipids, sialomucins and other glycoproteins, as well as secreted and circulating proteins. The glycocalyx/endothelial surface layer not only covers the glomerular endothelium; it extends into the endothelial fenestrae. Some glycocalyx components span or are attached to the apical endothelial cell plasma membrane and form the formal glycocalyx. Other components, including small proteoglycans and circulating proteins like albumin and orosomucoid, form the endothelial surface layer and are bound to the glycocalyx due to weak intermolecular interactions. Indeed, bound plasma albumin is a major constituent of the endothelial surface layer and contributes to its barrier function. A role for glomerular endothelial cells in the barrier of the glomerular capillary wall to protein filtration has been demonstrated by many elegant studies. However, it can only be fully understood in the context of other components, including the glomerular basement membrane, the podocytes and reabsorption of proteins by tubule epithelial cells. Discovery of the precise mechanisms that lead to glycocalyx/endothelial surface layer disruption within glomerular capillaries will hopefully lead to pharmacological interventions that specifically target this important structure.

Syndecans and Their Synstatins: Targeting an Organizer of Receptor Tyrosine Kinase Signaling at the Cell-Matrix Interface

Receptor tyrosine kinases (RTKs) and integrin matrix receptors have well-established roles in tumor cell proliferation, invasion and survival, often functioning in a coordinated fashion at sites of cell-matrix adhesion. Central to this coordination are syndecans, another class of matrix receptor, that organize RTKs and integrins into functional units, relying on docking motifs in the syndecan extracellular domains to capture and localize RTKs (e.g., EGFR, IGF-1R, VEGFR2, HER2) and integrins (e.g., αvβ3, αvβ5, α4β1, α3β1, α6β4) to sites of adhesion. Peptide mimetics of the docking motifs in the syndecans, called “synstatins”, prevent assembly of these receptor complexes, block their signaling activities and are highly effective against tumor cell invasion and survival and angiogenesis. This review describes our current understanding of these four syndecan-coupled mechanisms and their inhibitory synstatins (SSTN_IGF1R, SSTN_VEGFR2, SSTN_VLA-4, SSTN_EGFR and SSTN_HER2).

Syndecan-1 (CD138), Carcinomas and EMT

Cell surface proteoglycans are known to be important regulators of many aspects of cell behavior. The principal family of transmembrane proteoglycans is the syndecans, of which there are four in mammals. Syndecan-1 is mostly restricted to epithelia, and bears heparan sulfate chains that are capable of interacting with a large array of polypeptides, including extracellular matrix components and potent mediators of proliferation, adhesion and migration. For this reason, it has been studied extensively with respect to carcinomas and tumor progression. Frequently, but not always, syndecan-1 levels decrease as tumor grade, stage and invasiveness and dedifferentiation increase. This parallels experiments that show depletion of syndecan-1 can be accompanied by loss of cadherin-mediated adhesion. However, in some tumors, levels of syndecan-1 increase, but the characterization of its distribution is relevant. There can be loss of membrane staining, but acquisition of cytoplasmic and/or nuclear staining that is abnormal. Moreover, the appearance of syndecan-1 in the tumor stroma, either associated with its cellular component or the collagenous matrix, is nearly always a sign of poor prognosis. Given its relevance to myeloma progression, syndecan-1-directed antibody—toxin conjugates are being tested in clinical and preclinical trials, and may have future relevance to some carcinomas.

A guide to the composition and functions of the extracellular matrix

Extracellular matrix (ECM) is a dynamic 3-dimensional network of macromolecules that provides structural support for the cells and tissues. Accumulated knowledge clearly demonstrated over the last decade that ECM plays key regulatory roles since it orchestrates cell signaling, functions, properties and morphology. Extracellularly secreted as well as cell-bound factors are among the major members of the ECM family. Proteins/glycoproteins, such as collagens, elastin, laminins and tenascins, proteoglycans and glycosaminoglycans, hyaluronan, and their cell receptors such as CD44 and integrins, responsible for cell adhesion, comprise a well-organized functional network with significant roles in health and disease. On the other hand, enzymes such as matrix metalloproteinases and specific glycosidases including heparanase and hyaluronidases contribute to matrix remodeling and affect human health. Several cell processes and functions, among them cell proliferation and survival, migration, differentiation, autophagy, angiogenesis, and immunity regulation are affected by certain matrix components. Structural alterations have been also well associated with disease progression. This guide on the composition and functions of the ECM gives a broad overview of the matrisome, the major ECM macromolecules, and their interaction networks within the ECM and with the cell surface, summarizes their main structural features and their roles in tissue organization and cell functions, and emphasizes the importance of specific ECM constituents in disease development and progression as well as the advances in molecular targeting of ECM to design new therapeutic strategies.

Syndecans in cancer: A review of function, expression, prognostic value, and therapeutic significance

While our understanding of tumors and how to treat them has advanced significantly since the days of Aminopterin and the radical mastectomy, cancer remains among the leading causes of death worldwide. Despite innumerable advancements in medical technology the non-static and highly heterogeneous nature of a tumor can make characterization and treatment exceedingly difficult. Because of this complexity, the identification of new cellular constituents that can be used for diagnostic, prognostic, and therapeutic purposes is crucial in improving patient outcomes worldwide. Growing evidence has demonstrated that among the myriad of changes seen in cancer cells, the Syndecan family of proteins has been observed to undergo drastic alterations in expression. Syndecans are transmembrane heparan sulfate proteoglycans that are responsible for cell signaling, proliferation, and adhesion, and many studies have shed light on their unique involvement in both tumor progression and suppression. This review seeks to discuss Syndecan expression levels in various cancers, whether they make reliable biomarkers for detection and prognosis, and whether they may be viable targets for future cancer therapies. The conclusions drawn from the literature reviewed in this article indicate that changes in expression of Syndecan protein can have profound effects on tumor size, metastatic capability, and overall patient survival rate. Further, while data regarding the therapeutic targeting of Syndecan proteins is sparse, the available literature does demonstrate promise for their use in cancer treatment going forward.

Hold on or Cut? Integrin- and MMP-Mediated Cell-Matrix Interactions in the Tumor Microenvironment

The tumor microenvironment (TME) has become the focus of interest in cancer research and treatment. It includes the extracellular matrix (ECM) and ECM-modifying enzymes that are secreted by cancer and neighboring cells. The ECM serves both to anchor the tumor cells embedded in it and as a means of communication between the various cellular and non-cellular components of the TME. The cells of the TME modify their surrounding cancer-characteristic ECM. This in turn provides feedback to them via cellular receptors, thereby regulating, together with cytokines and exosomes, differentiation processes as well as tumor progression and spread. Matrix remodeling is accomplished by altering the repertoire of ECM components and by biophysical changes in stiffness and tension caused by ECM-crosslinking and ECM-degrading enzymes, in particular matrix metalloproteinases (MMPs). These can degrade ECM barriers or, by partial proteolysis, release soluble ECM fragments called matrikines, which influence cells inside and outside the TME. This review examines the changes in the ECM of the TME and the interaction between cells and the ECM, with a particular focus on MMPs.

Cell-surface heparan sulfate proteoglycans as multifunctional integrators of signaling in cancer

Proteoglycans (PGs) represent a large proportion of the components that constitute the extracellular matrix (ECM). They are a diverse group of glycoproteins characterized by a covalent link to a specific glycosaminoglycan type. As part of the ECM, heparan sulfate (HS)PGs participate in both physiological and pathological processes including cell recruitment during inflammation and the promotion of cell proliferation, adhesion and motility during development, angiogenesis, wound repair and tumor progression. A key function of HSPGs is their ability to modulate the expression and function of cytokines, chemokines, growth factors, morphogens, and adhesion molecules. This is due to their capacity to act as ligands or co-receptors for various signal-transducing receptors, affecting pathways such as FGF, VEGF, chemokines, integrins, Wnt, notch, IL-6/JAK-STAT3, and NF-κB. The activation of those pathways has been implicated in the induction, progression, and malignancy of a tumor. For many years, the study of signaling has allowed for designing specific drugs targeting these pathways for cancer treatment, with very positive results. Likewise, HSPGs have become the subject of cancer research and are increasingly recognized as important therapeutic targets. Although they have been studied in a variety of preclinical and experimental models, their mechanism of action in malignancy still needs to be more clearly defined. In this review, we discuss the role of cell-surface HSPGs as pleiotropic modulators of signaling in cancer and identify them as promising markers and targets for cancer treatment.

Actively Targeted Nanodelivery of Echinomycin Induces Autophagy-Mediated Death in Chemoresistant Pancreatic Cancer In Vivo

Pancreatic cancer remains a recalcitrant neoplasm associated with chemoresistance and high fatality. Because it is frequently resistant to apoptosis, exploiting autophagic cell death could offer a new treatment approach. We repurpose echinomycin, an antibiotic encapsulated within a syndecan-1 actively targeted nanoparticle, for treatment of pancreatic cancer. Tumor-specific uptake, biodistribution, efficacy of nanodelivered echinomycin, and mechanism of cell death were assessed in aggressive, metastatic models of pancreatic cancer. In these autophagic-dependent pancreatic cancer models, echinomycin treatment resulted in autophagic cell death noted by high levels of LC3 among other autophagy markers, but without hallmarks of apoptosis, e.g., caspase activation and chromatin fragmentation, or necrosis, e.g., plasma membrane degradation and chromatin condensation/degrading. In vivo, biodistribution of syndecan-1-targeted nanoparticles indicated preferential S2VP10 or S2CP9 tumor uptake compared to the liver and kidney (S2VP10 p = 0.0016, p = 0.00004 and S2CP9 p = 0.0009, p = 0.0001). Actively targeted nanodelivered echinomycin resulted in significant survival increases compared to Gemzar (S2VP10 p = 0.0003, S2CP9 p = 0.0017) or echinomycin only (S2VP10 p = 0.0096, S2CP9 p = 0.0073). We demonstrate that actively targeted nanodelivery of echinomycin results in autophagic cell death in pancreatic and potentially other high-autophagy, apoptosis-resistant tumors. Collectively, these findings support syndecan-1-targeted delivery of echinomycin and dysregulation of autophagy to induce cell death in pancreatic cancer.

Glypican-1 Level Is Elevated in Extracellular Vesicles Released from MC38 Colon Adenocarcinoma Cells Overexpressing Snail

The transcription factor Snail triggers epithelial-to-mesenchymal transition (EMT), endowing cancer cells with invasive properties during tumor progression. Extracellular vesicles (EVs) released from cancer cells at various stages of cancer progression are known to influence the tumor pre-metastatic niche and metastatic potential. The aim of this study was to analyze the effect of Snail on murine colon adenocarcinoma cells (MC38 line) and on the characteristics of their EVs. Stable clones of Snail-overexpressing MC38 cells were investigated in vitro versus Mock cells. Increased expression of matrix metalloproteinase MMP-14 and augmented activity of MMP-9 and -14 were observed in Snail-MC38 cells. There was no change in the transcriptomic profile of proteoglycans in Snail-MC38 cells; however, the protein level of Glypican-1 (GPC1) was enhanced in EVs released from those cells. Our finding that GPC1 protein level was enhanced in EVs released from MC38 cells that overexpressed Snail and were in an early EMT stage might explain the specificity of the GPC1 biomarker in colon cancer diagnosis. Further, our data suggest that Snail, by changing the level of GPC1 on EVs released by colon cancer cells, may affect the generation of a distant premetastatic niche and metastatic organotropism in colon adenocarcinoma.

Sulfated syndecan 1 is critical to preventing cellular senescence by modulating fibroblast growth factor receptor endocytosis

Cellular senescence can be triggered by various intrinsic and extrinsic stimuli. We previously reported that silencing of 3'-phosphoadenosine 5'-phosphosulfate synthetase 2 (PAPSS2) induces cellular senescence through augmented fibroblast growth factor receptor 1 (FGFR1) signaling. However, the exact molecular mechanism connecting heparan sulfation and cellular senescence remains unclear. Here, we investigated the potential involvement of heparan sulfate proteoglycans (HSPGs) in augmented FGFR1 signaling and cellular senescence. Depletion of several types of HSPGs revealed that cells depleted of syndecan 1 (SDC1) exhibited typical senescence phenotypes, and those depleted of PAPSS2-, SDC1-, or heparan sulfate 2-O sulfotransferase 1 (HS2ST1) showed decreased FGFR1 internalization along with hyperresponsiveness to and prolonged activation of fibroblast growth factor 2 (FGF2)-stimulated FGFR1- v-akt murine thymoma viral oncogene homolog (AKT) signaling. Clathrin- and caveolin-mediated FGFR1 endocytosis contributed to cellular senescence through the FGFR1-AKT-p53-p21 signaling pathway. Dynasore treatment triggered senescence phenotypes, augmented FGFR1-AKT-p53-p21 signaling, and decreased SDC1 expression. Finally, the replicatively and prematurely senescent cells were characterized by decreases of SDC1 expression and FGFR1 internalization, and an increase in FGFR1-AKT-p53-p21 signaling. Together, our results demonstrate that properly sulfated SDC1 plays a critical role in preventing cellular senescence through the regulation of FGFR1 endocytosis.

Alternagin-C (ALT-C), a disintegrin-like protein, attenuates alpha2beta1 integrin and VEGF receptor 2 signaling resulting in angiogenesis inhibition

Angiogenesis, a crucial process in tumor progression, is mainly regulated by vascular endothelial growth factor (VEGF) and its receptor, VEGFR2. Studies have shown the interaction between α₂β₁ integrin, a collagen receptor, and VEGFR2 in VEGF-driven angiogenesis in vitro and in vivo. Alternagin-C (ALT-C), an ECD-disintegrin-like protein from Bothrops alternatus snake venom, has high affinity for α₂β₁ integrin and shows antiangiogenic activity in concentrations higher than 100 nM. Despite previous results, its mechanism of action on angiogenic signaling pathways has not been addressed. Here we evaluate the antiangiogenic activity of ALT-C in human umbilical vein endothelial cells (HUVECs) associated or not with VEGF, as well as its interference in the α₂β₁/VEGFR2 crosstalk. ALT-C (1000 nM) affected actin cytoskeleton, decreased the number of cell filopodia, and strongly inhibited HUVEC tube formation, adhesion to type I collagen and cell migration. Down-regulation of α₂β₁/VEGFR2 crosstalk by ALT-C decreased the protein content and phosphorylation of VEGFR2 and β₁ integrin subunit, inhibited ERK 1/2 and PI3K signaling and regulated FAK/Src and paxillin pathways. Furthermore, ALT-C increased the content of the autophagic markers LC3B and Beclin-1 in the presence of VEGF, which is associated with decreased angiogenesis. In conclusion, we suggest that ALT-C, after binding to α₂β₁ integrin, inhibits VEGF/VEGFR2 signaling, which results in impaired angiogenesis. These results demonstrate that ALT-C may be a potential candidate for the development of antiangiogenic therapies for tumor and metastasis treatment and help to understand the complexity and fundamental role of integrin inhibition in the tumor microenvironment.

Tumor Microenvironment: Extracellular Matrix Alterations Influence Tumor Progression

The tumor microenvironment (TME) is composed of various cell types embedded in an altered extracellular matrix (ECM). ECM not only serves as a support for tumor cell but also regulates cell-cell or cell-matrix cross-talks. Alterations in ECM may be induced by hypoxia and acidosis, by oxygen free radicals generated by infiltrating inflammatory cells or by tumor- or stromal cell-secreted proteases. A poorer diagnosis for patients is often associated with ECM alterations. Tumor ECM proteome, also named cancer matrisome, is strongly altered, and different ECM protein signatures may be defined to serve as prognostic biomarkers. Collagen network reorganization facilitates tumor cell invasion. Proteoglycan expression and location are modified in the TME and affect cell invasion and metastatic dissemination. ECM macromolecule degradation by proteases may induce the release of angiogenic growth factors but also the release of proteoglycan-derived or ECM protein fragments, named matrikines or matricryptins. This review will focus on current knowledge and new insights in ECM alterations, degradation, and reticulation through cross-linking enzymes and on the role of ECM fragments in the control of cancer progression and their potential use as biomarkers in cancer diagnosis and prognosis.

Heparanase: A Dynamic Promoter of Myeloma Progression

It has been speculated for many years that heparanase plays an important role in the progression of cancer due largely to the finding that its expression is weak or absent in normal tissues but generally as tumors become more aggressive heparanase expression increases. However, it is only in the last decade or so that we have begun to understand the molecular mechanism behind the sinister role that heparanase plays in cancer. In this review, we describe the many functions of heparanase in promoting the growth, angiogenesis and metastasis of multiple myeloma, a devastating cancer that localizes predominantly within the bone marrow and spreads throughout the skeletal system devouring bone and ultimately leading to death of almost all patients diagnosed with this disease. We also explore recent discoveries related to how heparanase primes exosome biogenesis and how heparanase enhances myeloma tumor chemoresistance. Discovery of these multiple tumor-promoting pathways that are driven by heparanase identified the enzyme as an ideal target for therapy, an approach recently tested in a Phase I trial in myeloma patients.

Recombinant RGD-disintegrin DisBa-01 blocks integrin αvβ3 and impairs VEGF signaling in endothelial cells

Background

Integrins mediate cell adhesion, migration, and survival by connecting the intracellular machinery with the surrounding extracellular matrix. Previous studies demonstrated the interaction between α_vβ₃ integrin and VEGF type 2 receptor (VEGFR2) in VEGF-induced angiogenesis. DisBa-01, a recombinant His-tag fusion, RGD-disintegrin from Bothrops alternatus snake venom, binds to α_vβ₃ integrin with nanomolar affinity blocking cell adhesion to the extracellular matrix. Here we present in vitro evidence of a direct interference of DisBa-01 with α_vβ₃/VEGFR2 cross-talk and its downstream pathways.

Methods

Human umbilical vein (HUVECs) were cultured in plates coated with fibronectin (FN) or vitronectin (VN) and tested for migration, invasion and proliferation assays in the presence of VEGF, DisBa-01 (1000 nM) or VEGF and DisBa-01 simultaneously. Phosphorylation of α_vβ₃/VEGFR2 receptors and the activation of intracellular signaling pathways were analyzed by western blotting. Morphological alterations were observed and quantified by fluorescence confocal microscopy.

Results

DisBa-01 treatment of endothelial cells inhibited critical steps of VEGF-mediated angiogenesis such as migration, invasion and tubulogenesis. The blockage of α_vβ₃/VEGFR2 cross-talk by this disintegrin decreases protein expression and phosphorylation of VEGFR2 and β₃ integrin subunit, regulates FAK/SrC/Paxillin downstream signals, and inhibits ERK1/2 and PI3K pathways. These events result in actin re-organization and inhibition of HUVEC migration and adhesion. Labelled-DisBa-01 colocalizes with α_vβ₃ integrin and VEGFR2 in treated cells.

Conclusions

Disintegrin inhibition of α_vβ₃ integrin blocks VEGFR2 signalling, even in the presence of VEGF, which impairs the angiogenic mechanism. These results improve our understanding concerning the mechanisms of pharmacological inhibition of angiogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0339-1) contains supplementary material, which is available to authorized users.

Soluble syndecans: biomarkers for diseases and therapeutic options

Syndecans are important mediators of signalling by transmitting external stimuli into the cells. This role in signal transduction has been attributed mainly to the membrane-bound syndecans. In the last years, however, the soluble ectodomain of syndecans generated by shedding has come into the focus of research as this process has been show to modulate the syndecan-dependent signalling pathways, as well as other pathways. This review summarizes the current knowledge about the induction of syndecan shedding and the different pathways modulated by shed syndecan proteins. This review summarizes the known and putative sheddases for each syndecan and describes the exemplary conditions of sheddase activity for some syndecans. This review summarizes the proposed use of shed syndecans as biomarkers for various diseases, as the shedding process of syndecans depends crucially on tissue- and disease-specific activation of the sheddases. Furthermore, the potential use of soluble syndecans as a therapeutic option is discussed, on the basis of the current literature. LINKED ARTICLES: This article is part of a themed section on Translating the Matrix. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.1/issuetoc.

Glycosylation and Integrin Regulation in Cancer

Integrins are transmembrane receptors that coordinate extracellular matrix (ECM)-cell and cell-cell interactions, signal transmission, gene expression, and cell function. The aberration of integrin function is one of the well-recognized mechanisms of cancer. The activity of integrins is strongly influenced by glycans through glycosylation events and the establishment of glycan-mediated interactions. Glycans represent a class of ubiquitous biomolecules that display an extraordinary complexity and diversity in both structure and function. Widely expressed both in the ECM and on the cell surface, they play a crucial role in mediating cell proliferation, survival, and metastasis during cancer. The purpose of this review is to provide an overview of how both glycosylation of integrins and integrin interaction with the cancer glyco-microenvironment can regulate cancer progression.

Inhibition of the signaling pathway of syndecan-1 by synstatin: A promising anti-integrin inhibitor of angiogenesis and proliferation in HCC in rats

AIM OF WORK

The study was conducted for evaluation of the antitumor activity of SSTN_92-119 against HCC induced by thioacetamide in rats.

METHODS

Sixty male Sprague-Dawley rats were randomized into four equal groups: Control, SSTN_92-119, HCC, and HCC + SSTN_92-119. Liver function tests were measured in serum. Liver homogenate was used for determination of: i) integrinαѴβ3 (ITGαѴβ3), insulin like growth factor-1 receptor (IGF-1R), vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2) and alpha-fetoprotein (AFP) levels by ELISA, ii) syndecan-1 (CD-138), IGF-1R and VEGF genes expressions by qRT-PCR, iii) MDA, NO, GSH concentrations and SOD activity. Histopathological and immunohistochemical examination of liver tissue was performed.

RESULTS

SSTN_92-119 decreased HCC-induced elevation in ALT, AST, ALP and GGT activities and reversed HCC-induced reduction in total protein and albumin concentrations significantly. SSTN_92-119 significantly elevated hepatic SOD and GSH and reduced both NO and MDA levels. Protein levels of ITGαѴβ3, IGF-1R, VEGF, FGF-2 and AFP were decreased in HCC- SSTN_92-119 group as well as gene expression of CD-138, IGF-1R and VEGF compared with HCC group.

CONCLUSIONS

SSTN_92-119 down regulates ITGαѴβ3 receptor and subsequently reduces the activation of angiogenic growth factors VEGF and FGF-2. Therefore, SSTN_92-119 is becoming a promising anti-integrin αѴβ3 that inhibits angiogenesis and proliferation in HCC.

Crosstalk between VEGFR and other receptor tyrosine kinases for TKI therapy of metastatic renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma (RCC), and is frequently accompanied by the genetic features of von Hippel–Lindau (VHL) loss. VHL loss increases the expression of hypoxia-inducible factors (HIFs) and their targets, including epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF). The primary treatment for metastatic RCC (mRCC) is molecular-targeted therapy, especially anti-angiogenic therapy. VEGF monoclonal antibodies and VEGF receptor (VEGFR) tyrosine kinase inhibitors (TKIs) are the main drugs used in anti-angiogenic therapy. However, crosstalk between VEGFR and other tyrosine kinase or downstream pathways produce resistance to TKI treatment, and the multi-target inhibitors, HIF inhibitors or combination strategies are promising strategies for mRCC. HIFs are upstream of the crosstalk between the growth factors, and these factors may regulate the expression of VEGR, EGF, PDGF and other growth factors. The frequent VHL loss in ccRCC increases HIF expression, and HIFs may be an ideal candidate to overcome the TKI resistance. The combination of HIF inhibitors and immune checkpoint inhibitors is also anticipated. Various clinical trials of programmed cell death protein 1 inhibitors are planned. The present study reviews the effects of current and potential TKIs on mRCC, with a focus on VEGF/VEGFR and other targets for mRCC therapy.

The Role of Endothelial Surface Glycocalyx in Mechanosensing and Transduction

The endothelial cells (ECs) forming the inner wall of every blood vessel are constantly exposed to the mechanical forces generated by blood flow. The EC responses to these hemodynamic forces play a critical role in the homeostasis of the circulatory system. A variety of mechanosensors and transducers, locating on the EC surface, intra- and trans-EC membrane, and within the EC cytoskeleton, have thus been identified to ensure proper functions of ECs. Among them, the most recent candidate is the endothelial surface glycocalyx (ESG), which is a matrix-like thin layer covering the luminal surface of the EC. It consists of various proteoglycans, glycosaminoglycans, and plasma proteins and is close to other prominent EC mechanosensors and transducers. This chapter summarizes the ESG composition, thickness, and structure observed by different labeling and visualization techniques and in different types of vessels. It also presents the literature in determining the ESG mechanical properties by atomic force microscopy and optical tweezers. The molecular mechanisms by which the ESG plays the role in EC mechanosensing and transduction are described as well as the ESG remodeling by shear stress, the actin cytoskeleton, the membrane rafts, the angiogenic factors, and the sphingosine-1-phosphate.

Fragments generated upon extracellular matrix remodeling: Biological regulators and potential drugs

The remodeling of the extracellular matrix (ECM) by several protease families releases a number of bioactive fragments, which regulate numerous biological processes such as autophagy, angiogenesis, adipogenesis, fibrosis, tumor growth, metastasis and wound healing. We review here the proteases which generate bioactive ECM fragments, their ECM substrates, the major bioactive ECM fragments, together with their biological properties and their receptors. The translation of ECM fragments into drugs is challenging and would take advantage of an integrative approach to optimize the design of pre-clinical and clinical studies. This could be done by building the contextualized interaction network of the ECM fragment repertoire including their parent proteins, remodeling proteinases, and their receptors, and by using mathematical disease models.

Shedding of Syndecan-1/CXCL1 Complexes by Matrix Metalloproteinase 7 Functions as an Epithelial Checkpoint of Neutrophil Activation

Although neutrophils play critical roles in innate immunity, in excess these cells cause severe tissue damage. Thus, neutrophil activation must be tightly regulated to prevent indiscriminant damage. Previously, we reported that mice lacking matrix metalloproteinase (MMP) 7 are protected from lung injury owing to markedly impaired neutrophil movement from the interstitium into mucosal lumenal spaces. This phenotype resulted from a lack of MMP7 shedding of syndecan-1, a heparan sulfate proteoglycan that carries the neutrophil chemokine CXCL1 as cargo. Here, we assessed if shedding syndecan-1/CXCL1 complexes affects neutrophil activation. Whereas injured monolayers of wild-type alveolar type II cells potently stimulated neutrophil activation, as gauged by release of myeloperoxidase, cells from Mmp7(-/-) or syndecan-1-null (Sdc1(-/-)) mice or human cells with MMP7 knockdown did not. In vivo, we observed reduced myeloperoxidase release relative to neutrophil numbers in bleomycin-injured Mmp7(-/-) and Sdc1(-/-) mice. Furthermore, we determined that soluble syndecan-1 directly stimulated neutrophil activation in the absence of cellular damage. These data indicate that MMP7 shedding of syndecan-1/CXCL1 complexes functions as a checkpoint that restricts neutrophil activation at sites of epithelial injury.

Syndecan-1 Acts as an Important Regulator of CXCL1 Expression and Cellular Interaction of Human Endometrial Stromal and Trophoblast Cells

Successful implantation of the embryo into the human receptive endometrium is substantial for the establishment of a healthy pregnancy. This study focusses on the role of Syndecan-1 at the embryo-maternal interface, the multitasking coreceptor influencing ligand concentration, release and receptor presentation, and cellular morphology. CXC motif ligand 1, being involved in chemotaxis and angiogenesis during implantation, is of special interest as a ligand of Syndecan-1. Human endometrial stromal cells with and without Syndecan-1 knock-down were decidualized and treated with specific inhibitors to evaluate signaling pathways regulating CXC ligand 1 expression. Western blot analyses of MAPK and Wnt members were performed, followed by analysis of spheroid interactions between human endometrial cells and extravillous trophoblast cells. By mimicking embryo contact using IL-1β, we showed less ERK and c-Jun activation by depletion of Syndecan-1 and less Frizzled 4 production as part of the canonical Wnt pathway. Additionally, more beta-catenin was phosphorylated and therefore degraded after depletion of Syndecan-1. Secretion of CXC motif ligand 1 depends on MEK-1 with respect to Syndecan-1. Regarding the interaction of endometrial and trophoblast cells, the spheroid center-to-center distances were smaller after depletion of Syndecan-1. Therefore, Syndecan-1 seems to affect signaling processes relevant to signaling and intercellular interaction at the trophoblast-decidual interface.

IGF-IR cooperates with ERα to inhibit breast cancer cell aggressiveness by regulating the expression and localisation of ECM molecules

IGF-IR is highly associated with the behaviour of breast cancer cells. In ERα-positive breast cancer, IGF-IR is present at high levels. In clinical practice, prolonged treatment with anti-estrogen agents results in resistance to the therapy with activation of alternative signaling pathways. Receptor Tyrosine Kinases, and especially IGF-IR, have crucial roles in these processes. Here, we report a nodal role of IGF-IR in the regulation of ERα-positive breast cancer cell aggressiveness and the regulation of expression levels of several extracellular matrix molecules. In particular, activation of IGF-IR, but not EGFR, in MCF-7 breast cancer cells results in the reduction of specific matrix metalloproteinases and their inhibitors. In contrast, IGF-IR inhibition leads to the depletion by endocytosis of syndecan-4. Global important changes in cell adhesion receptors, which include integrins and syndecan-4 triggered by IGF-IR inhibition, regulate adhesion and invasion. Cell function assays that were performed in MCF-7 cells as well as their ERα-suppressed counterparts indicate that ER status is a major determinant of IGF-IR regulatory role on cell adhesion and invasion. The strong inhibitory role of IGF-IR on breast cancer cells aggressiveness for which E2-ERα signaling pathway seems to be essential, highlights IGF-IR as a major molecular target for novel therapeutic strategies.

Extracellular Matrix, a Hard Player in Angiogenesis

The extracellular matrix (ECM) is a complex network of proteins, glycoproteins, proteoglycans, and polysaccharides. Through multiple interactions with each other and the cell surface receptors, not only the ECM determines the physical and mechanical properties of the tissues, but also profoundly influences cell behavior and many physiological and pathological processes. One of the functions that have been extensively explored is its impingement on angiogenesis. The strong impact of the ECM in this context is both direct and indirect by virtue of its ability to interact and/or store several growth factors and cytokines. The aim of this review is to provide some examples of the complex molecular mechanisms that are elicited by these molecules in promoting or weakening the angiogenic processes. The scenario is intricate, since matrix remodeling often generates fragments displaying opposite effects compared to those exerted by the whole molecules. Thus, the balance will tilt towards angiogenesis or angiostasis depending on the relative expression of pro- or anti-angiogenetic molecules/fragments composing the matrix of a given tissue. One of the vital aspects of this field of research is that, for its endogenous nature, the ECM can be viewed as a reservoir to draw from for the development of new more efficacious therapies to treat angiogenesis-dependent pathologies.

Insulin-like growth factor axis targeting in cancer and tumour angiogenesis - the missing link

Numerous molecular players in the process of tumour angiogenesis have been shown to offer potential for therapeutic targeting. Initially denoted to be involved in malignant transformation and tumour progression, the insulin-like growth factor (IGF) signalling axis has been subject to therapeutic interference, albeit with limited clinical success. More recently, IGFs and their receptors have received attention for their contribution to tumour angiogenesis, which offers novel therapeutic opportunities. Here we review the contribution of this signalling axis to tumour angiogenesis, the mechanisms of resistance to therapy and the interplay with other pro-angiogenic pathways, to offer insight in the renewed interest in the application of IGF axis targeting agents in anti-cancer combination therapies.

Targeting Syndecan-1, a molecule implicated in the process of vasculogenic mimicry, enhances the therapeutic efficacy of the L19-IL2 immunocytokine in human melanoma xenografts

Anti-angiogenic therapy of solid tumors has until now failed to produce the long lasting clinical benefits desired, possibly due to the complexity of the neoangiogenic process. Indeed, a prominent role is played by “vasculogenic” or “vascular” mimicry (VM), a phenomenon in which aggressive cancer cells form an alternative microvascular circulation, independently of endothelial cell angiogenesis. In this study we observed, in melanoma patient cell lines having vasculogenic/stem-cell like phenotype and in melanoma tumors, the syndecan-1 co-expression with VM markers, such as CD144 and VEGFR-2. We show that melanoma cells lose their ability to form tubule-like structures in vitro after blocking syndecan-1 activity by the specific human recombinant antibody, OC-46F2. Moreover, in a human melanoma xenograft model, the combined therapy using OC-46F2 and L19-IL2, an immunocytokine specific for the tumor angiogenic-associated B-fibronectin isoform(B-FN), led to a complete inhibition of tumor growth until day 90 from tumor implantation in 71% of treated mice, with statistically significant differences compared to groups treated with OC-46F2 or L19-IL2 as monotherapy. Furthermore, in the tumors recovered from mice treated with OC-46F2 either as monotherapy or in combination with L19-IL2, we observed a dramatic decrease of vascular density and loss of VM structures. These findings indicate for the first time a role of syndecan-1 in melanoma VM and that targeting syndecan-1, together with B-FN, could be promising in improving the treatment of metastatic melanoma.

Syndecan-1 Attenuates Lung Injury during Influenza Infection by Potentiating c-Met Signaling to Suppress Epithelial Apoptosis

RATIONALE

Syndecan-1 is a cell surface heparan sulfate proteoglycan primarily expressed in the lung epithelium. Because the influenza virus is tropic to the airway epithelium, we investigated the role of syndecan-1 in influenza infection.

OBJECTIVES

To determine the mechanism by which syndecan-1 regulates the lung mucosal response to influenza infection.

METHODS

Wild-type (WT) and Sdc1(-/-) mice were infected with a H1N1 virus (PR8) as an experimental model of influenza infection. Human and murine airway epithelial cell cultures were also infected with PR8 to study the mechanism by which syndecan-1 regulates the inflammatory response.

MEASUREMENT AND MAIN RESULTS

We found worsened outcomes and lung injury in Sdc1(-/-) mice compared with WT mice after influenza infection. Our data demonstrated that syndecan-1 suppresses bronchial epithelial apoptosis during influenza infection to limit widespread lung inflammation. Furthermore, we determined that syndecan-1 attenuated apoptosis by crosstalking with c-Met to potentiate its cytoprotective signals in airway epithelial cells during influenza infection.

CONCLUSIONS

Our work shows that cell-associated syndecan-1 has an important role in regulating lung injury. Our findings demonstrate a novel mechanism in which cell membrane-associated syndecan-1 regulates the innate immune response to influenza infection by facilitating cytoprotective signals through c-Met signaling to limit bronchial epithelial apoptosis, thereby attenuating lung injury and inflammation.

Mechanisms and regulation of endothelial VEGF receptor signalling

Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are uniquely required to balance the formation of new blood vessels with the maintenance and remodelling of existing ones, during development and in adult tissues. Recent advances have greatly expanded our understanding of the tight and multi-level regulation of VEGFR2 signalling, which is the primary focus of this Review. Important insights have been gained into the regulatory roles of VEGFR-interacting proteins (such as neuropilins, proteoglycans, integrins and protein tyrosine phosphatases); the dynamics of VEGFR2 endocytosis, trafficking and signalling; and the crosstalk between VEGF-induced signalling and other endothelial signalling cascades. A clear understanding of this multifaceted signalling web is key to successful therapeutic suppression or stimulation of vascular growth.

Syndecan-1 (CD138) Suppresses Apoptosis in Multiple Myeloma by Activating IGF1 Receptor: Prevention by SynstatinIGF1R Inhibits Tumor Growth

Syndecan-1 (Sdc1/CD138) expression is linked to disease severity in multiple myeloma, although the causal basis for this link remains unclear. Here we report that capture of the IGF1 receptor (IGF1R) by Sdc1 suppresses ASK1-dependent apoptosis in multiple myeloma cells. Sdc1 binds two different fractions of IGF1R, one that is constitutively active and a second that is activated by IGF1 ligand. Notably, IGF1R kinase activity in both fractions is blocked by synstatinIGF1R (SSTNIGF1R), a peptide that inhibits IGF1R capture by Sdc1, as well as by a truncated peptide (SSTNIGF1R-T) that appears to be specific for multiple myeloma cells. Mechanistically, we show that ASK1 is bound to active IGF1R and inhibited by Tyr and Ser83/Ser966 phosphorylation. When IGF1R engagement with Sdc1 is blocked by SSTNIGF1R, ASK1 becomes activated, and initiates JNK- and caspase-3-mediated apoptosis. In pharmacologic tests, we find SSTNIGF1R is highly stable in human plasma and displays a half-life of 27 hours in mice, wherein it significantly reduces both the size and neovascularization of CAG myeloma tumor xenografts. Taken together, our results offer a preclinical proof of concept and mechanistic rationale for the exploration of SSTNIGF1R as an experimental therapeutic to dually attack multiple myeloma tumor cell survival and tumor angiogenesis. Cancer Res; 76(17); 4981-93. ©2016 AACR.

Heparanase-induced shedding of syndecan-1/CD138 in myeloma and endothelial cells activates VEGFR2 and an invasive phenotype: prevention by novel synstatins

Multiple myeloma arises when malignant plasma cells invade and form multiple tumors in the bone marrow. High levels of heparanase (HPSE) correlate with poor prognosis in myeloma patients. A likely target of the enzyme is the heparan sulfate (HS) proteoglycan syndecan-1 (Sdc1, CD138), which is highly expressed on myeloma cells and contributes to poor prognosis in this disease. We find that HPSE promotes an invasive phenotype mediated by the very late antigen-4 (VLA-4, or α4β1 integrin) in myeloma cells plated on either fibronectin (FN) or vascular endothelial cell adhesion molecule-1 (VCAM-1), ligands that are prevalent in the bone marrow. The phenotype depends on vascular endothelial cell growth factor receptor-2 (VEGFR2), which is aberrantly expressed in myeloma, and is characterized by a highly protrusive lamellipodium and cell invasion. HPSE-mediated trimming of the HS on Sdc1 and subsequent matrix metalloproteinase-9-mediated shedding of the syndecan exposes a juxtamembrane site in Sdc1 that binds VEGFR2 and VLA-4, thereby coupling VEGFR2 to the integrin. Shed Sdc1 can be mimicked by recombinant Sdc1 ectodomain or by a peptide based on its binding motif, which causes VLA-4 to re-orient from the lagging edge (uropod) to the leading edge of migrating cells, couple with and activate VEGFR2. Peptides (called 'synstatins') containing only the VLA-4 or VEGFR2 binding sites competitively inhibit invasion, as they block coupling of the receptors. This mechanism is also utilized by vascular endothelial cells, in which it is also activated by HPSE, during endothelial cell tube formation. Collectively, our findings reveal for the first time the mechanism through which HPSE modulates Sdc1 function to promote both tumor cell invasion and angiogenesis, thereby driving multiple myeloma progression. The inhibitory synstatins, or inhibitors of HPSE enzyme activity, are likely to show promise as therapeutics against myeloma extravasation and spread.

Effects of Controlled Cortical Impact on the Mouse Brain Vasculome

Perturbations in blood vessels play a critical role in the pathophysiology of brain injury and neurodegeneration. Here, we use a systematic genome-wide transcriptome screening approach to investigate the vasculome after brain trauma in mice. Mice were subjected to controlled cortical impact and brains were extracted for analysis at 24 h post-injury. The core of the traumatic lesion was removed and then cortical microvesels were isolated from nondirectly damaged ipsilateral cortex. Compared to contralateral cortex and normal cortex from sham-operated mice, we identified a wide spectrum of responses in the vasculome after trauma. Up-regulated pathways included those involved in regulation of inflammation and extracellular matrix processes. Decreased pathways included those involved in regulation of metabolism, mitochondrial function, and transport systems. These findings suggest that microvascular perturbations can be widespread and not necessarily localized to core areas of direct injury per se and may further provide a broader gene network context for existing knowledge regarding inflammation, metabolism, and blood-brain barrier alterations after brain trauma. Further efforts are warranted to map the vasculome with higher spatial and temporal resolution from acute to delayed phase post-trauma. Investigating the widespread network responses in the vasculome may reveal potential mechanisms, therapeutic targets, and biomarkers for traumatic brain injury.

Heparin Decreases in Tumor Necrosis Factor α (TNFα)-induced Endothelial Stress Responses Require Transmembrane Protein 184A and Induction of Dual Specificity Phosphatase 1

Despite the large number of heparin and heparan sulfate binding proteins, the molecular mechanism(s) by which heparin alters vascular cell physiology is not well understood. Studies with vascular smooth muscle cells (VSMCs) indicate a role for induction of dual specificity phosphatase 1 (DUSP1) that decreases ERK activity and results in decreased cell proliferation, which depends on specific heparin binding. The hypothesis that unfractionated heparin functions to decrease inflammatory signal transduction in endothelial cells (ECs) through heparin-induced expression of DUSP1 was tested. In addition, the expectation that the heparin response includes a decrease in cytokine-induced cytoskeletal changes was examined. Heparin pretreatment of ECs resulted in decreased TNFα-induced JNK and p38 activity and downstream target phosphorylation, as identified through Western blotting and immunofluorescence microscopy. Through knockdown strategies, the importance of heparin-induced DUSP1 expression in these effects was confirmed. Quantitative fluorescence microscopy indicated that heparin treatment of ECs reduced TNFα-induced increases in stress fibers. Monoclonal antibodies that mimic heparin-induced changes in VSMCs were employed to support the hypothesis that heparin was functioning through interactions with a receptor. Knockdown of transmembrane protein 184A (TMEM184A) confirmed its involvement in heparin-induced signaling as seen in VSMCs. Therefore, TMEM184A functions as a heparin receptor and mediates anti-inflammatory responses of ECs involving decreased JNK and p38 activity.

Pharmacological models and approaches for pathophysiological conditions associated with hypoxia and oxidative stress

Hypoxia is the failure of oxygenation at the tissue level, where the reduced oxygen delivered is not enough to satisfy tissue demands. Metabolic depression is the physiological adaptation associated with reduced oxygen consumption, which evidently does not cause any harm to organs that are exposed to acute and short hypoxic insults. Oxidative stress (OS) refers to the imbalance between the generation of reactive oxygen species (ROS) and the ability of endogenous antioxidant systems to scavenge ROS, where ROS overwhelms the antioxidant capacity. Oxidative stress plays a crucial role in the pathogenesis of diseases related to hypoxia during intrauterine development and postnatal life. Thus, excessive ROS are implicated in the irreversible damage to cell membranes, DNA, and other cellular structures by oxidizing lipids, proteins, and nucleic acids. Here, we describe several pathophysiological conditions and in vivo and ex vivo models developed for the study of hypoxic and oxidative stress injury. We reviewed existing literature on the responses to hypoxia and oxidative stress of the cardiovascular, renal, reproductive, and central nervous systems, and discussed paradigms of chronic and intermittent hypobaric hypoxia. This systematic review is a critical analysis of the advantages in the application of some experimental strategies and their contributions leading to novel pharmacological therapies.

Molecular and clinical profiles of syndecan-1 in solid and hematological cancer for prognosis and precision medicine

Syndecan-1 (SDC1, CD138) is a key cell surface adhesion molecule essential for maintaining cell morphology and interaction with the surrounding microenvironment. Deregulation of SDC1 contributes to cancer progression by promoting cell proliferation, metastasis, invasion and angiogenesis, and is associated with relapse through chemoresistance. SDC1 expression level is also associated with responses to chemotherapy and with prognosis in multiple solid and hematological cancers, including multiple myeloma and Hodgkin lymphoma. At the tissue level, the expression levels of SDC1 and the released extracellular domain of SDC1 correlate with tumor malignancy, phenotype, and metastatic potential for both solid and hematological tumors in a tissue-specific manner. The SDC1 expression profile varies among cancer types, but the differential expression signatures between normal and cancer cells in epithelial and stromal compartments are directly associated with aggressiveness of tumors and patient's clinical outcome and survival. Therefore, relevant biomarkers of SDC signaling may be useful for selecting patients that would most likely respond to a particular therapy at the time of diagnosis or perhaps for predicting relapse. In addition, the reciprocal expression signature of SDC between tumor epithelial and stromal compartments may have synergistic value for patient selection and the prediction of clinical outcome.

Syndecan-1 and Syndecan-4 Capture Epidermal Growth Factor Receptor Family Members and the α3β1 Integrin Via Binding Sites in Their Ectodomains: NOVEL SYNSTATINS PREVENT KINASE CAPTURE AND INHIBIT α6β4-INTEGRIN-DEPENDENT EPITHELIAL CELL MOTILITY

The α6β4 integrin is known to associate with receptor tyrosine kinases when engaged in epithelial wound healing and in carcinoma invasion and survival. Prior work has shown that HER2 associates with α6β4 integrin and syndecan-1 (Sdc1), in which Sdc1 engages the cytoplasmic domain of the β4 integrin subunit allowing HER2-dependent motility and carcinoma cell survival. In contrast, EGFR associates with Sdc4 and the α6β4 integrin, and EGFR-dependent motility depends on cytoplasmic engagement of β4 integrin with Sdc4. However, how HER2 and EGFR assimilate into a complex with the syndecans and integrin, and why kinase capture is syndecan-specific has remained unknown. In the present study, we demonstrate that HER2 is captured via a site, comprised of amino acids 210-240, in the extracellular domain of human Sdc1, and EGFR is captured via an extracellular site comprised of amino acids 87-131 in human Sdc4. Binding assays using purified recombinant proteins demonstrate that the interaction between the EGFR family members and the syndecans is direct. The α3β1 integrin, which is responsible for the motility of the cells, is captured at these sites as well. Peptides based on the interaction motifs in Sdc1 and Sdc4, called synstatins (SSTN210-240 and SSTN87-131) competitively displace the receptor tyrosine kinase and α3β1 integrin from the syndecan with an IC50 of 100-300 nm. The syndecans remain anchored to the α6β4 integrin via its cytoplasmic domain, but the activation of cell motility is disrupted. These novel SSTN peptides are potential therapeutics for carcinomas that depend on these HER2- and EGFR-coupled mechanisms for their invasion and survival.

Shed syndecan-2 inhibits angiogenesis

Angiogenesis is essential for the development of a normal vasculature, tissue repair and reproduction, and also has roles in the progression of diseases such as cancer and rheumatoid arthritis. The heparan sulphate proteoglycan syndecan-2 is expressed on mesenchymal cells in the vasculature and, like the other members of its family, can be shed from the cell surface resulting in the release of its extracellular core protein. The purpose of this study was to establish whether shed syndecan-2 affects angiogenesis. We demonstrate that shed syndecan-2 regulates angiogenesis by inhibiting endothelial cell migration in human and rodent models and, as a result, reduces tumour growth. Furthermore, our findings show that these effects are mediated by the protein tyrosine phosphatase receptor CD148 (also known as PTPRJ) and this interaction corresponds with a decrease in active β1 integrin. Collectively, these data demonstrate an unexplored pathway for the regulation of new blood vessel formation and identify syndecan-2 as a therapeutic target in pathologies characterised by angiogenesis.

Syndecans in angiogenesis and endothelial cell biology

Syndecans are multifunctional heparan sulfate proteoglycans (HSPGs) with roles in cell adhesion, migration, receptor trafficking and growth-factor interactions and signalling. Studies using syndecan null animals have revealed limited roles for syndecans during development; however, under conditions of challenge or insult, several phenotypes have emerged. Angiogenesis is an important process both in development and in wound healing, but also in pathologies such as cancer and chronic inflammatory conditions. In the present paper, we summarize the main studies elucidating the role of syndecans in angiogenesis and their potential as novel therapeutic targets.

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

Vasculature is present in all tissues and therefore is indispensable for development, biology, and pathology of multicellular organisms. Endothelial cells guarantee proper function of the vessels and are the original component in angiogenesis. Morphogenesis of the vascular system utilizes processes like cell adhesion, motility, proliferation, and survival that are closely related to the dynamics of actin filaments and actin-tethered adhesion complexes. Here we review involvement of actin cytoskeleton-associated junctional molecules of endothelial cells in angiogenesis and lymphangiogenesis. Particularly, we focus on F-actin binding protein afadin, an adaptor protein involved in broad range of signaling mechanisms. Afadin mediates the pathways of vascular endothelial growth factor- (VEGF-) and sphingosine 1-phosphate-triggered angiogenesis and is essential for embryonic development of lymph vessels in mice. We propose that targeting actin-tethered junctional molecules, including afadin, may present a new approach to angiogenic therapy that in combination with today used medications like VEGF inhibitors will benefit against development of pathological angiogenesis.