Adhesion events in angiogenesis

β1 integrins play a critical role maintaining vascular integrity in the hypoxic spinal cord, particularly in white matter

Interactions between extracellular matrix (ECM) proteins and β1 integrins play an essential role maintaining vascular integrity in the brain, particularly under vascular remodeling conditions. As blood vessels in the spinal cord are reported to have distinct properties from those in the brain, here we examined the impact of β1 integrin inhibition on spinal cord vascular integrity, both under normoxic conditions, when blood vessels are stable, and during exposure to chronic mild hypoxia (CMH), when extensive vascular remodeling occurs. We found that a function-blocking β1 integrin antibody triggered a small degree of vascular disruption in the spinal cord under normoxic conditions, but under hypoxic conditions, it greatly enhanced (20-fold) vascular disruption, preferentially in spinal cord white matter (WM). This resulted in elevated microglial activation as well as marked loss of myelin integrity and reduced density of oligodendroglial cells. To understand why vascular breakdown is localized to WM, we compared expression levels of major BBB components of WM and grey matter (GM) blood vessels, but this revealed no obvious differences. Interestingly however, hypoxyprobe staining demonstrated that the most severe levels of spinal cord hypoxia induced by CMH occurred in the WM. Analysis of brain tissue revealed a similar preferential vulnerability of WM tracts to show vascular disruption under these conditions. Taken together, these findings demonstrate an essential role for β1 integrins in maintaining vascular integrity in the spinal cord, and unexpectedly, reveal a novel and fundamental difference between WM and GM blood vessels in their dependence on β1 integrin function during hypoxic exposure. Our data support the concept that the preferential WM vulnerability described may be less a result of intrinsic differences in vascular barrier properties between WM and GM, and more a consequence of differences in vascular density and architecture.

β1 integrin is essential for blood-brain barrier integrity under stable and vascular remodelling conditions; effects differ with age

BACKGROUND

Maintaining a tight blood-brain barrier (BBB) is an important prerequisite for the preservation of neurological health, though current evidence suggests it declines with age. While extracellular matrix-integrin interactions play critical roles in regulating the balance between vascular stability and remodeling, it remains to be established whether manipulation of integrin function weakens or strengthens vascular integrity. Indeed, recent reports have generated conflicting outcomes in this regard.

METHODS

Here, in young (8-10 weeks) and aged (20 months) mice, we examined the impact of intraperitoneal injection of a function-blocking β1 integrin antibody, both under normoxic conditions, when the BBB is stable, and during chronic mild hypoxic (CMH; 8% O₂) conditions, when a vigorous vascular remodeling response is ongoing. Brain tissue was examined by immunofluorescence (IF) for markers of vascular remodeling and BBB disruption, and microglial activation and proliferation. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison post-hoc test.

RESULTS

In both young and aged mice, β1 integrin block greatly amplified hypoxia-induced vascular disruption, though it was much less under normoxic conditions. Interestingly, under both normoxic and hypoxic conditions, β1 integrin antibody-induced BBB disruption was greater in young mice. Enhanced BBB breakdown was associated with increased levels of the leaky BBB marker MECA-32 and with greater loss of endothelial tight junction proteins and the adherens protein VE-cadherin. Surprisingly, β1 integrin blockade did not reduce hypoxia-induced endothelial proliferation, nor did it prevent the hypoxia-associated increase in vascularity. Commensurate with the increased vascular disruption, β1 integrin blockade enhanced microglial activation both in young and aged brain, though the impact was much greater in young brain. In vitro studies revealed that β1 integrin blockade also reduced the integrity of a brain endothelial monolayer and triggered disruptions in tight junction proteins.

CONCLUSIONS

These data demonstrate that β1 integrin plays an essential role in maintaining BBB integrity, both under stable normoxic conditions and during hypoxia-induced vascular remodeling. As β1 integrin blockade had a greater disruptive effect in young brain, effectively shifting the BBB phenotype of young brain towards that of the aged, we speculate that enhancing β1 integrin function at the aged BBB may hold therapeutic potential by reverting the deteriorating BBB phenotype back towards that of the young.

Endothelial cell spreading on lipid bilayers with combined integrin and cadherin binding ligands

Endothelial cells play a central role in the vascular system, where their function is tightly regulated by both cell-extracellular matrix (e.g., via integrins) and cell-cell interactions (e.g., via cadherins). In this study, we incorporated cholesterol-modified integrin and N-cadherin peptide binding ligands in fluid supported lipid bilayers. Human umbilical vein endothelial cell adhesion, spreading and vinculin localization in these cells were dependent on ligand density. One composition led to observe a higher extent of cell spreading, where cells exhibited extensive lamellipodia formation and a qualitatively more distinct N-cadherin localization at the cell periphery, which is indicative of N-cadherin clustering and a mimic of cell-cell contact formation. The results can be used to reconstitute the endothelial-pericyte interface on biomedical devices and materials.

SCUBE3 serves as an independent poor prognostic factor in breast cancer

BACKGROUND

Accumulating evidences indicate that the signal peptide-CUB-EGF-like domain-containing protein 3 (SCUBE3) plays a key role in the development and progression of many human cancers. However, the underlying mechanism and prognosis value of SCUBE3 in breast cancer are still unclear.

METHODS

The clinical data of 137 patients with breast cancer who underwent surgical resection in Taizhou Hospital of Zhejiang Province were retrospectively analyzed. We first conducted a comprehensive study on the expression pattern of SCUBE3 using the Tumor Immune Estimation Resource (TIMER) and UALCAN databases. In addition, the expression of SCUBE3 in breast tumor tissues was confirmed by immunohistochemistry. The protein-protein interaction analysis and functional enrichment analysis of SCUBE3 were analyzed using the STRING and Enrichr databases. Moreover, tissue microarray (TMA) was used to analyze the relationship between SCUBE3 expression levels and clinical-pathological parameters, such as histological type, grade, the status of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor (HER2). We further supplemented and identified the above results using the UALCAN and bc-GenExMiner v4.4 databases from TCGA data. The correlation between the expression of SCUBE3 and survival was calculated by multivariate Cox regression analysis to investigate whether SCUBE3 expression may be an independent prognostic factor of breast cancer.

RESULTS

We found that the expression level of SCUBE3 was significantly upregulated in breast cancer tissue compared with adjacent normal tissues. The results showed that the distribution of breast cancer patients in the high expression group and the low expression group was significantly different in ER, PR, HER2, E-cadherin, and survival state (p < 0.05), but there was no significant difference in histologic grade, histologic type, tumor size, lymph node metastasis, TMN stage, subtypes, or recurrence (p > 0.05). In addition, the high expression of SCUBE3 was associated with relatively poor prognosis of ER- (p = 0.012), PR- (p = 0.029), HER2 + (p = 0.007). The multivariate Cox regression analysis showed that the hazard ratio (HR) was 2.80 (95% CI 1.20-6.51, p = 0.0168) in individuals with high SCUBE3 expression, and HR was increased by 1.86 (95% CI 1.06-3.25, p = 0.0300) for per 1-point increase of SCUBE3 expression.

CONCLUSIONS

These findings demonstrate that the high expression of SCUBE3 indicates poor prognosis in breast cancer. SCUBE3 expression may serve as a potential diagnostic indicator of breast cancer.

Niche-Mediated Integrin Signaling Supports Steady-State Hematopoiesis in the Spleen

Outside-in integrin signaling regulates cell fate decisions in a variety of cell types, including hematopoietic stem cells (HSCs). Our earlier published studies showed that interruption of periostin (POSTN) and integrin-αv (ITGAV) interaction induces faster proliferation in HSCs with developmental stage-dependent functional effects. In this study, we examined the role of POSTN-ITGAV axis in lymphohematopoietic activity in spleen that hosts a rare population of HSCs, the functional regulation of which is not clearly known. Vav-iCre-mediated deletion of Itgav in the hematopoietic system led to higher proliferation rates, resulting in increased frequency of primitive HSCs in the adult spleen. However, in vitro CFU-C assays demonstrated a poorer differentiation potential following Itgav deletion. This also led to a decrease in the white pulp area with a significant decline in the B cell numbers. Systemic deletion of its ligand, POSTN, phenocopied the effects noted in Vav-Itgav^-/- mice. Histological examination of Postn-deficient spleen also showed an increase in the spleen trabecular areas. Importantly, these are the myofibroblasts of the trabecular and capsular areas that expressed high levels of POSTN within the spleen tissue. In addition, vascular smooth muscle cells also expressed POSTN. Through CFU-S₁₂ assays, we showed that hematopoietic support potential of stroma in Postn-deficient splenic hematopoietic niche was defective. Overall, we demonstrate that POSTN-ITGAV interaction plays an important role in spleen lymphohematopoiesis.

A Role of Agrin in Maintaining the Stability of Vascular Endothelial Growth Factor Receptor-2 during Tumor Angiogenesis

Endothelial cell (EC) recruitment is central to the vascularization of tumors. Although several proteoglycans have been implicated in cancer and angiogenesis, their roles in EC recruitment and vascularization during tumorigenesis remain poorly understood. Here, we reveal that Agrin, which is secreted in liver cancer, promotes angiogenesis by recruiting ECs within tumors and metastatic lesions and facilitates adhesion of cancer cells to ECs. In ECs, Agrin-induced angiogenesis and adherence to cancer cells are mediated by Integrin-β1, Lrp4-MuSK pathways involving focal adhesion kinase. Mechanistically, we uncover that Agrin regulates VEGFR2 levels that sustain the angiogenic property of ECs and adherence to cancer cells. Agrin attributes an ECM stiffness-based stabilization of VEGFR2 by enhancing interactions with Integrin-β1-Lrp4 and additionally stimulates endothelial nitric-oxide synthase (e-NOS) signaling. Therefore, we propose that cross-talk between Agrin-expressing cancer and ECs favor angiogenesis by sustaining the VEGFR2 pathway.

The role of CD44 in pathological angiogenesis

Angiogenesis is required for normal development and occurs as a pathological step in a variety of disease settings, such as cancer, ocular diseases, and ischemia. Recent studies have revealed the role of CD44, a widely expressed cell surface adhesion molecule, in promoting pathological angiogenesis and the development of its associated diseases through its regulation of diverse function of endothelial cells, such as proliferation, migration, adhesion, invasion, and communication with the microenvironment. Conversely, the absence of CD44 expression or inhibition of its function impairs pathological angiogenesis and disease progression. Here, we summarize the current understanding of the roles of CD44 in pathological angiogenesis and the underlying cellular and molecular mechanisms.

The Periostin/Integrin-αv Axis Regulates the Size of Hematopoietic Stem Cell Pool in the Fetal Liver

We earlier showed that outside-in integrin signaling through POSTN-ITGAV interaction plays an important role in regulating adult hematopoietic stem cell (HSC) quiescence. Here, we show that Itgav deletion results in increased frequency of phenotypic HSCs in fetal liver (FL) due to faster proliferation. Systemic deletion of Postn led to increased proliferation of FL HSCs, albeit without any loss of stemness, unlike Vav-Itgav^−/− HSCs. Based on RNA sequencing analysis of FL and bone marrow HSCs, we predicted the involvement of DNA damage response pathways in this dichotomy. Indeed, proliferative HSCs from Postn-deficient FL tissues showed increased levels of DNA repair, resulting in lesser double-strand breaks. Thus POSTN, with its expression majorly localized in the vascular endothelium of FL tissue, acts as a regulator of stem cell pool size during development. Overall, we demonstrate that the duality of response to proliferation in HSCs is developmental stage dependent and can be correlated with DNA damage responses.

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Interruption of POSTN-ITGAV interaction leads to HSC expansion in fetal liver

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HSC from fetal liver in comparison with adult BM excel in their DNA damage responses

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POSTN is a potential component of the vascular niche for HSCs in the fetal liver

Effect of magnesium-degradation products and hypoxia on the angiogenesis of human umbilical vein endothelial cells

Biodegradable magnesium (Mg) metals have been applied in orthopaedic and stent applications due to their biodegradability, bioabsorbability and adaptability to tissue regeneration. However, further investigations are still needed to understand how angiogenesis will respond to high concentrations of Mg and oxygen content differences, which are vital to vascular remodelling and bone fracture regeneration or tissue healing. Human primary endothelial cells were exposed to various concentrations (2-8 mM) of extracellular Mg degradation products under either hypoxia or normoxia. Increased proliferation was measured with Mg extracts under hypoxia but not under normoxia. Under normoxia and with Mg extracts, HUVEC migration exhibited a bell-shaped curve. The same pattern was observed with VEGFB expression, while VEGFA was constantly downregulated. Under hypoxia, migration and VEGFA levels remained constant; however, VEGFB was upregulated. Similarly, under normoxia, tube formation as well as VEGFA and VEGFB levels were downregulated. Nevertheless, under hypoxia, tube formation remained constant while VEGFA and VEGFB levels were upregulated. These results suggest that Mg extracts did not interfere with angiogenesis under hypoxia. STATEMENT OF SIGNIFICANCE: Neoangiogenesis, mediated by (e.g.) hypoxia, is a key factor for proper tissue healing Thus, effect of Mg degradation products under either hypoxia or normoxia on angiogenesis were investigated. Under normoxia and increased Mg concentrations, a general negative effect was measured on early (migration) and late (tubulogenesis) angiogenesis. However, under hypoxia, this effect was abolished. As magnesium degradation is an oxygen-dependant process, hypoxia condition may be a relevant factor to test material cytocompatibility in vitro.

Design of an Amphiphilic Poly(aspartamide)-mediated Self-assembled Nanoconstruct for Long-Term Tumor Targeting and Bioimaging

Biodegradable polymers have been developed for the targeted delivery of therapeutics to tumors. However, tumor targeting and imaging are usually limited by systemic clearance and non-specific adsorption. In this study, we used poly(amino acid) derivatives, such as poly(succinimide), to synthesize a nanomicelle-forming poly(hydroxyethylaspartamide) (PHEA, P) modified sequentially with octadecylamine, polyethylene glycol (PEG, P), and glycine (G) to design PHEA-PEG-glycine (PPG) nanoparticles (NPs). These PPG NPs were further tethered to cyclic Arg-Gly-Asp (cRGD) sequences for formulating tumor-targeting PPG-cRGD NPs, and then loaded with IR-780 dye (PPG-cRGD-IR-780) for visualizing tumor homing. cRGD cloaked in PPG NPs could bind specifically to both tumor endothelium and cancer cells overexpressing α_vβ₃ integrins. PPG-cRGD NPs exhibited enhanced physiological stability, cellular viability, and targeted intracellular uptake in cancer cells. In addition, PPG-cRGD NPs offered enhanced systemic circulation, leading to preferential tumor targeting and prolonged fluorescence tumor imaging for nearly 30 days. Nevertheless, non-targeted formulations demonstrated premature systemic clearance with short-term tumor imaging. Histochemical analysis showed no damage to normal organs, reaffirming the biocompatibility of PHEA polymers. Overall, our results indicated that PPG-cRGD NPs, which were manipulated to obtain optimal particle size and surface charge, and were complemented with tumor targeting, could improve the targeted and theranostic potential of therapeutic delivery.

Roles of blood-brain barrier integrins and extracellular matrix in stroke

Ischemicstroke is a leading cause of death and disability in the United States, but recent advances in treatments [i.e., endovascular thrombectomy and tissue plasminogen activator (t-PA)] that target the stroke-causing blood clot, while improving overall stroke mortality rates, have had much less of an impact on overall stroke morbidity. This may in part be attributed to the lack of therapeutics targeting reperfusion-induced injury after the blood clot has been removed, which, if left unchecked, can expand injury from its core into the surrounding at risk tissue (penumbra). This occurs in two phases of increased permeability of the blood-brain barrier, a physical barrier that under physiologic conditions regulates brain influx and efflux of substances and consists of tight junction forming endothelial cells (and transporter proteins), astrocytes, pericytes, extracellular matrix, and their integrin cellular receptors. During, embryonic development, maturity, and following stroke reperfusion, cerebral vasculature undergoes significant changes including changes in expression of integrins and degradation of surrounding extracellular matrix. Integrins, heterodimers with α and β subunits, and their extracellular matrix ligands, a collection of proteoglycans, glycoproteins, and collagens, have been modestly studied in the context of stroke compared with other diseases (e.g., cancer). In this review, we describe the effect that various integrins and extracellular matrix components have in embryonic brain development, and how this changes in both maturity and in the poststroke environment. Particular focus will be on how these changes in integrins and the extracellular matrix affect blood-brain barrier components and their potential as diagnostic and therapeutic targets for ischemic stroke.

131 -Oxophorbine protopheophorbide A from Ziziphus lotus as a novel mesenchymal-epithelial transition factor receptor inhibitory lead for the control of breast tumor growth in vitro and in vivo

The failure of chemotherapy especially in triple negative breast cancer (TNBC) patients has been correlated with the overexpression of the mesenchymal-epithelial transition factor (c-Met) receptor. Thus, the hepatocyte growth factor (HGF)/c-Met signaling axis has gained considerable attention as a valid molecular target for breast cancer therapy. This study reports for the first time the discovery of the 13¹ -oxophorbines pheophorbide A and protopheophorbide A along with chlorophyllide A from Ziziphus lotus, an edible typical Tunisian plant, as the potent antiproliferative compounds against the human breast cancer cells MDA-MB-231 and MCF-7. Compared to other compounds, protopheophorbide A exerted the highest light-independent antiproliferative effect against the metastatic TNBC MDA-MB-231 cells (IC₅₀  = 6.5 μM). In silico, this compound targeted the kinase domain of multiple c-Met crystal structures. It potently inhibited the kinase domain phosphorylation of wild and mutant c-Met in Z-LYTE kinase assay. Protopheophorbide A inhibited HGF-induced downstream c-Met-dependent cell proliferation, survival, adhesion and migration through RAF/MEK/ERK and PI3K/PTEN/AKT signaling pathways modulation, ROS generation and activation of JNK and p38 pathways. Interestingly, this compound impaired the ability of the MDA-MB-231 cells to adhere at different extracellular matrix proteins by reducing the HGF-induced expression of integrins αv, β3, α2, and β1. Moreover, protopheophorbide A exhibited anti-migratory properties (IC₅₀  = 2.2 μM) through impacting the expression levels of E-cadherin, vimentin, β-catenin, FAK, Brk, Rac, and Src proteins. Importantly, treatment with protopheophorbide A significantly inhibited the MDA-MB-231 tumor growth in vivo. Our results suggest that protopheophorbide A could be a novel c-Met inhibitory lead with promise to control c-Met/HGF-dependent breast malignancies.

Immunomodulatory and enhanced antitumor activity of a modified thymosin α1 in melanoma and lung cancer

Tumor-targeted therapy is an attractive strategy for cancer treatment. Peptide hormone thymosin α1 (Tα1) has been used against several diseases, including cancer, but its activity is pleiotropic. Herein, we designed a fusion protein Tα1-iRGD by introducing the tumor homing peptide iRGD to Tα1. Results show that Tα1-iRGD can promote T-cell activation and CD86 expression, thereby exerting better effect and stronger inhibitory against melanoma and lung cancer, respectively, than Tα1 in vivo. These effects are indicated by the reduced densities of tumor vessels and Tα1-iRGD accumulation in tumors. Moreover, compared with Tα1, Tα1-iRGD can attach more B16F10 and H460 cells and exhibits significantly better immunomodulatory activity in immunosuppression models induced by hydrocortisone. Circular dichroism spectroscopy and structural analysis results revealed that Tα1 and Tα1-iRGD both adopted a helical confirmation in the presence of trifluoroethanol, indicating the structural basis of their functions. These findings highlight the vital function of Tα1-iRGD in tumor-targeted therapy and suggest that Tα1-iRGD is a better antitumor drug than Tα1.

Comparative in vitro/theoretical studies on the anti-angiogenic activity of date pollen hydro-alcoholic extract: Highlighting the important roles of its hot polyphenols

Introduction: Date palm pollen (DPP) is the male reproductive soft powder from date flowers widely used as the valuable dietary supplement to fortify the size of testis and ovarian to increase the power of sex. This part of date palm significantly exhibited anti-diabetic, anti-inflammation and protective effects against male and female infertility. Though the anticancer activity of date fruits was previously reported, the DPP anti-angiogenic effects were not reported, and as the first study, its inhibitory effects were examined in the current study.

Methods: The DPP soft powder was collected to prepare its hydro-alcoholic extract to examine its anti-angiogenic activity in an in vitro model. At different concentrations, the cytotoxicity of the prepared extract was examined on human umbilical vein endothelial cells (HUVECs) using lactate dehydrogenase method. Cell proliferation was determined using the MTT assay and cytodex-3D model in collagen gel was used to assay its possible anti-angiogenic activity. The expression of VEGF, MMP-2 and MMP-9 genes was measured using real-time polymerase chain reaction (PCR). Finally, molecular docking simulation was used to highlight the possible role of DPP polyphenols to interact with the associated receptors.

Results: The prepared hydro-alcoholic extract exhibited significant anti-angiogenic activity in a dose-dependent manner and decreased the endothelial cell proliferation. The calculated IC₅₀ value for the examined extract in angiogenesis model was 260 µg·mL, respectively. Also, the expression of VEGF, MMP-2 and MMP-9 genes were significantly decreased. Docking simulation results unveiled that the isolated DPP polyphenols have the affinity to interact with ctDNA, VEGF and its receptors.

Conclusion: The DPP is the new source of non-toxic anti-cancer agents to use as a dietary supplement in the pre-treatment of cancer.

Micropatterning as a tool to identify regulatory triggers and kinetics of actin-mediated endothelial mechanosensing

Developmental processes, such as angiogenesis, are associated with a constant remodeling of the actin cytoskeleton in response to different mechanical stimuli. The mechanosensitive transcription factors MRTF-A (MKL1) and YAP (also known as YAP1) are important mediators of this challenging adaptation process. However, it is as yet unknown whether both pathways respond in an identical or in a divergent manner to a given microenvironmental guidance cue. Here, we use a micropatterning approach to dissect single aspects of cellular behavior in a spatiotemporally controllable setting. Using the exemplary process of angiogenesis, we show that cell-cell contacts and adhesive surface area are shared regulatory parameters of MRTF and YAP on rigid 2D surfaces. By analyzing MRTF and YAP under laminar flow conditions and during cell migration on dumbbell-shaped microstructures, we demonstrate that they exhibit different translocation kinetics. In conclusion, our work promotes the application of micropatterning techniques as a cell biological tool to study mechanosensitive signaling in the context of angiogenesis.

Peptides as drug delivery vehicles across biological barriers

Peptides are small biological molecules that are attractive in drug delivery and materials engineering for applications including therapeutics, molecular building blocks and cell-targeting ligands. Peptides are small but can possess complexity and functionality as larger proteins. Due to their intrinsic properties, peptides are able to overcome the physiological and transport barriers presented by diseases. In this review, we discuss the progress of identifying and using peptides to shuttle across biological barriers and facilitate transport of drugs and drug delivery systems for improved therapy. Here, the focus of this review is on rationally designed, phage display peptides, and even endogenous peptides as carriers to penetrate biological barriers, specifically the blood-brain barrier(BBB), the gastrointestinal tract (GI), and the solid tumor microenvironment (T). We will discuss recent advances of peptides as drug carriers in these biological environments. From these findings, challenges and potential opportunities to iterate and improve peptide-based approaches will be discussed to translate their promise towards the clinic to deliver drugs for therapeutic efficacy.

Synergistic suppression of a disintegrin acurhagin-C in combination with AZD4547 and reparixin on terminating development for human osteosarcoma MG-63 cell

Current therapies available for the treatment of human osteosarcoma, an aggressive bone tumor, are insufficient. To examine an alternative approach of integrin-based anti-osteosacoma strategy, acurhagin-C, a Glu-Cys-Asp (ECD)-disintegrin, was isolated and evaluated for its application in combination with two potent inhibitors of basic fibroblast growth factor (bFGF) and interleukin-8 (IL-8). The investigation of human osteosarcoma MG-63 cells pre-incubated with a FGF receptor-1 (FGFR-1) blocker AZD4547, a CXC-chemokine receptor-1/-2 (CXCR1/2) antagonist reparixin, and acurhagin-C via two given modes of separation and combination was executed. Detected by flow cytometry, integrins-α2/-α5/-αv/-β1, FGFR-1, CXCR1 and CXCR2 constitutively express on the resting membrane. However, bFGF/IL-8-activated MG-63 cells only statistically enhanced the surface exposure of integrins-α5/-β1, FGFR-1 and CXCR2. In activated MG-63 cells, acurhagin-C targeting integrin-α5 not only might potentiate the inhibitory effect of AZD4547 and reparixin on the surface expression of integrin-α5, FGFR-1 and CXCR2, but also acurhagin-C used alone remained effectively to diminish the surface exposure of those targeted receptors. Hence, a complicated crosstalk mechanism should be involved in the membrane interactions. Furthermore, co-administration of acurhagin-C with AZD4547 and reparixin also showed to have the synergistic suppression toward cell proliferation and the gene expression of matrix metalloproteinase-2. Also, the administration of three-in-one mode could nearly abrogate the cellular attachment onto collagen-IV- and fibronectin-coated wells, as well as penetration into Matrigel-barrier. These data supported an ECD-disintegrin acurhagin-C targeting integrin-α5 upon combined used with AZD4547 and reparixin may become a promising therapeutic approach for attenuating osteosarcoma development.

Sulfonation of Tyrosine as a Method To Improve Biodistribution of Peptide-Based Radiotracers: Novel 18F-Labeled Cyclic RGD Analogues

Control of the biodistribution of radiolabeled peptides has proven to be a major challenge in their application as imaging agents for positron emission tomography (PET). Modification of peptide hydrophilicity in order to increase renal clearance has been a common endeavor to improve overall biodistribution. Herein, we examine the effect of site-specific sulfonation of tyrosine moieties in cyclic(RGDyK) peptides as a means to enhance their hydrophilicity and improve their biodistribution. The novel sulfonated cyclic(RGDyK) peptides were conjugated directly to 4-nitrophenyl 2-[¹⁸F]fluoropropionate, and the biodistribution of the radiolabeled peptides was compared with that of their nonsulfonated, clinically relevant counterparts, [¹⁸F]GalactoRGD and [¹⁸F]FPPRGD2. Site-specific sulfonation of the tyrosine residues was shown to increase hydrophilicity and improve biodistribution of the RGD peptides, despite contributing just 79 Da toward the MW, compared with 189 Da for both the "Galacto" and mini-PEG moieties, suggesting this may be a broadly applicable approach to enhancing biodistribution of radiolabeled peptides.

CXCR4-targeted modular peptide carriers for efficient anti-VEGF siRNA delivery

The application of small interfering RNA (siRNA) for specific gene inhibition is a promising strategy in gene therapy treatments. The efficient cellular delivery of therapeutic siRNA is a critical step in RNA interference (RNAi) application. Highly efficient siRNA carriers should be developed for specific cellular uptake, stable RNA-complexes formation and intracellular RNA release. To study these features, we evaluated modular peptide carriers bearing CXCR4 targeting ligand for their ability to condense siRNA, facilitate endosomal escape and VEGFA gene silencing in CXCR4-expressing endothelial and glioblastoma cells. Peptide carriers were shown to condense and protect siRNA from RNAse degradation. Various N/P ratios were used for physicochemical characterization to optimize siRNA/peptide complexes for in vitro studies. On average, cytotoxicity of siRNA-polyplexes depended on cell type and was not higher than that of PEI/siRNA complexes. VEGFA gene knockdown was significantly improved with CXCR4-targeted carriers in contrast to nontargeted peptides. siRNA delivery by means of ligandconjugated carriers resulted in 2.5-3-fold decrease of VEGF expression in glioblastoma cells and in 1.5-2-fold decrease of VEGF expression in endothelial cells. Delivery of siRNA/peptide complexes resulted in 2-6- fold decrease in VEGF protein yield and in significant inhibition of endothelial cells migration. The study shows that implication of peptide carriers modified with CXCR4 ligand is a promising approach to develop targeted siRNA delivery system into CXCR4-expressing cancer and endothelial cells.

Effect of Thyrotropin on Osteopontin, Integrin αvβ3, and VCAM-1 in the Endothelium via Activation of Akt

Numerous epidemiological studies have shown that subclinical hypothyroidism (SCH) can impair endothelial function and cause dyslipidemia. Studies have evaluated the effects of thyroid stimulating hormone (TSH) on endothelial cells, but the mechanism underlying the proatherosclerotic effect of increased TSH levels remains unclear. In the present study, SCH rat models were established in thyroidectomized Wistar rats that were given l-T₄ daily. The results showed that in vivo, the expression of osteopontin (OPN) vascular cell adhesion molecule (VCAM-1), and levels of integrin α_vβ₃ in the aortic tissue in SCH and Hypothyroidism (CH) groups was higher than in the control group. However, the effect in the SCH group was higher than in the CH group. In vitro, results showed that different concentration and time gradients of TSH stimulation could increase the expression of OPN, VCAM-1, and integrin α_vβ₃, and this was accompanied by extracellular signal regulated kinase 1/2 (Erk1/2) and Akt activation in human umbilical vein endothelial cells (HUVECs). TSH induced elevation of these proatherosclerotic factors was partially suppressed by a specific Akt inhibitor but not by a specific Erk inhibitor. Findings suggested that the endothelial dysfunction caused by SCH was related to increased proatherosclerotic factors induced by TSH via Akt activation.

Inhibition of 5-lipoxygenase suppresses vascular endothelial growth factor-induced angiogenesis in endothelial cells

5-Lipoxygenase (5-LOX) is an enzyme that converts arachidonic acid from the cell membrane into leukotriene, a signal lipid mediator. 5-LOX deficiency markedly attenuates the formation of aneurysms in knockout mice. In addition, Zileuton, a clinical drug targeting 5-LOX, is used for treatment of asthma. However, it is unclear whether 5-LOX inhibition results in anti-angiogenic effects for applications in cancer therapy. To explore the roles of 5-LOX in angiogenesis and its potential as a therapeutic target in cancer, the effects of a newly synthesized 5-LOX inhibitor, F3, on in vitro and in vivo angiogenesis were investigated. The results showed that 5-LOX inhibition by F3 suppressed in vitro vascular endothelial growth factor (VEGF)-induced tube formation and chemo-invasion of endothelial cells (ECs). 5-LOX inhibition also decreased VEGF-induced extracellular signal-regulated kinase (ERK) phosphorylation in ECs. Notably, 5-LOX knockdown phenocopied the anti-angiogenic activity of the 5-LOX inhibitor F3 in a concentration-dependent manner. F3 did not affect the activities of VEGF receptor 2 or AKT. In vivo, the compound significantly inhibited the formation of the chorioallantoic membrane at nontoxic doses. These results demonstrated that 5-LOX played an important role in angiogenesis and that its inhibitor F3 could be a new anti-angiogenic agent targeting VEGF signaling.

Tobacco toxins deposited on surfaces (third hand smoke) impair wound healing

Third hand smoke (THS) is the accumulation of second hand smoke (SHS) toxins on surfaces in homes, cars, clothing and hair of smokers. It is known that 88M US nonsmokers ≥3 years old living in homes of smokers are exposed to THS toxicants and show blood cotinine levels of ≥0.05 ng/ml, indicating that the toxins are circulating in their circulatory systems. The goal of the present study is to investigate the mechanisms by which THS causes impaired wound healing. We show that mice living under conditions that mimic THS exposure in humans display delayed wound closure, impaired collagen deposition, altered inflammatory response, decreased angiogenesis, microvessels with fibrin cuffs and a highly proteolytic wound environment. Moreover, THS-exposed mouse wounds have high levels of oxidative stress and significantly lower levels of antioxidant activity leading to molecular damage, including protein nitration, lipid peroxidation and DNA damage that contribute to tissue dysfunction. Furthermore, we show that elastase is elevated, suggesting that elastin is degraded and the plasticity of the wound tissue is decreased. Taken together, our results lead us to conclude that THS toxicants delay and impair wound healing by disrupting the sequential processes that lead to normal healing. In addition, the lack of elastin results in loss of wound plasticity, which may be responsible for reopening of wounds.

A modified thymosin alpha 1 inhibits the growth of breast cancer both in vitro and in vivo: suppressment of cell proliferation, inducible cell apoptosis and enhancement of targeted anticancer effects

Thymosin alpha 1 (Tα1) is commonly used for treating several diseases; however its usage has been limited because of poor penetration of the target tissue, such as tumor cells. In the present study, Tα1-iRGD, a peptide by conjugating Tα1 with the iRGD fragment, was evaluated its performance in MCF-7 and MDA-MB-231 human breast cancer cells. Compared with the wild-type peptide, Tα1-iRGD was more selective in binding tumor cells in the cell attachment assay. Furthermore, the MTT assay confirmed that Tα1-iRGD proved more effective in significantly inhibiting the growth of MCF-7 cells in contrast to the general inhibition displayed by Tα1. Further, conjugation of Tα1 with iRGD preserved the immunomodulatory activity of the drug by increasing the proliferation of mouse spleen lymphocytes. Further, compared with Tα1 treatment, Tα1-iRGD treatment of MCF-7 cells considerably increased the number of cells undergoing apoptosis, resulting in a dose-dependent inhibition of cancer cell growth, which was associated with a much better effect on up-regulation of the expression of BCL2-associated X protein (Bax), caspase 9, etc. More importantly, treatment with Ta1-iRGD was more efficacious than treatment with Ta1 in vivo. This study highlights the importance of iRGD on enhancement of cell penetration and tumor accumulation. In summary, our findings demonstrate that the novel modified Tα1 developed in this study has the potential to be used for treating breast cancer.

Lunasin suppresses the migration and invasion of breast cancer cells by inhibiting matrix metalloproteinase-2/-9 via the FAK/Akt/ERK and NF-κB signaling pathways

Lunasin is a naturally existing bioactive peptide with an Arg-Gly-Asp (RGD) motif, which competes with integrins to bind with the extracellular matrix (ECM) consequently suppressing the integrin-mediated signaling pathway. Owing to the RGD motif, lunasin has been proven as an effective anti-inflammatory, antitumor and antimetastatic agent in many types of cancer. However, knowledge of its inhibitory effect on metastasis and the related mechanism of action in breast cancer cells is limited. In this study, the inhibitory effect of lunasin on the proliferation, migration and invasion of two typical breast cancer cell lines, ER-negative MDA-MB-231 with αVβ3 expression and ER-positive MCF-7 with αVβ5/α5β1 expression, were examined in vitro as well the related mechanisms. The results demonstrated that lunasin (10-20 µM) effectively inhibited the migration and invasion activity and expression of matrix metalloproteinase (MMP)‑2/-9 in both breast cancer cell lines. Meanwhile, we also found that lunasin inhibited the phosphorylation of focal adhesion kinase (FAK), Src, Akt, ERK and nucleus translocation of NF-κB, which indicates that, possibly via competing with αVβ3 or αVβ5/α5β1 integrin, lunasin suppresses the metastasis of breast cancer cells through integrin-mediated FAK/Akt/ERK and NF-κB signaling pathways followed by downregulation of the activity and expression of MMP-2/-9.

Improvement of cytocompatibility of 3D-printing resins for endothelial cell adhesion

We developed a new method for improving the biocompatibility of 3D-printing photosensitive resins using waterborne polyurethane (WPU) as the coating material.

Matrix metalloproteinase-9 mediates post-hypoxic vascular pruning of cerebral blood vessels by degrading laminin and claudin-5

Vascular remodeling involves a highly coordinated break-down and build-up of the vascular basal lamina and inter-endothelial tight junction proteins. In light of the important role of matrix metalloproteinases (MMPs) in tissue remodeling, the goal of this study was to examine the role of MMP-9 in remodeling of cerebral blood vessels, both in hypoxia-induced angiogenesis and in the vascular pruning that accompanies the switch from hypoxia back to normoxia. In a chronic mild hypoxia model of cerebrovascular remodeling, gel zymography revealed that MMP-9 levels were increased, both during hypoxic-induced angiogenesis and in the post-hypoxic pruning response. Interestingly, compared to wild-type mice, MMP-9 KO mice showed no alteration in hypoxic-induced angiogenesis, but did show marked delay in post-hypoxic vascular pruning. In wild-type mice, vascular pruning was associated with fragmentation of vascular laminin and the tight junction protein claudin-5, while this process was markedly attenuated in MMP-9 KO mice. In vitro experiments showed that hypoxia stimulated MMP-9 expression in brain endothelial cells but not pericytes. These results show that while MMP-9 is not essential for hypoxic-induced cerebral angiogenesis, it plays an important role in post-hypoxic vascular pruning by degrading laminin and claudin-5.

Increased antitumor activity of tumor-specific peptide modified thymopentin

Thymopoietin pentapeptide (thymopentin, TP5), an immunomodulatory peptide, has been successfully used as an immune system enhancer for treating immune deficiency, cancer, and infectious diseases. However, poor penetration into tumors remains a key limitation to the efficacy and application of TP5. iRGD (CRGDK/RGPD/EC) has been introduced to certain anticancer agents, and increased specific tumor penetrability of drugs and cell internalization have been observed. In the present study, we fused this iRGD fragment with the C-terminal of TP5 to yield a new product, TP5-iRGD. Cell attachment assay showed that TP5-iRGD exhibits more extensive attachment to the melanoma cell line B16F10 than wild-type TP5. Tumor cell viability assay showed that iRGD conjugation with the TP5 C-terminus increases the basal antiproliferative activity of the pentapeptide against the melanoma cell line B16F10, the human lung cancer cell line H460, and the human breast cancer cell line MCF-7. Subsequent injections of TP5-iRGD inhibited in vivo melanoma progression more efficiently than the native TP5. Murine spleen lymphocyte proliferation assay also showed that TP5-iRGD and the parent pentapeptide feature nearly identical spleen lymphocyte proliferation activities. We built an integrin αvβ3 and TP5-iRGD computational binding model to investigate the mechanism by which TP5-iRGD promotes increased activity further. Conjugation with iRGD promotes binding to integrin αvβ3, thereby increasing the tumor-homing efficiency of the resultant peptide. These experimental and computational observations of increased TP5-iRGD activity help broaden the usage of TP5 and reflect the great application potential of the peptide as an anticancer agent.

Phage nanofibers induce vascularized osteogenesis in 3D printed bone scaffolds

A virus-activated matrix is developed to overcome the challenge of forming vascularized bone tissue. It is generated by filling a 3D printed bioceramic scaffold with phage nanofibers displaying high-density RGD peptide. After it is seeded with mesenchymal stem cells (MSCs) and implanted into a bone defect, the phage nanofibers induce osteogenesis and angiogenesis by activating endothelialization and osteogenic differentiation of MSCs.

Non-collagenous ECM proteins in blood vessel morphogenesis and cancer

BACKGROUND

The extracellular matrix (ECM) is constituted by diverse composite structures, which determine the specific to each organ, histological architecture and provides cells with biological information, mechanical support and a scaffold for adhesion and migration. The pleiotropic effects of the ECM stem from the dynamic changes in its molecular composition and the ability to remodel in order to effectively regulate biological outcomes. Besides collagens, fibronectin and laminin are two major fiber-forming constituents of various ECM structures.

SCOPE OF REVIEW

This review will focus on the properties and the biological functions of non-collagenous extracellular matrix especially on laminin and fibronectin that are currently emerging as important regulators of blood vessel formation and function in health and disease.

MAJOR CONCLUSIONS

The ECM is a fundamental component of the microenvironment of blood vessels, with activities extending beyond providing a vascular scaffold; extremely versatile it directly or indirectly modulates all essential cellular functions crucial for angiogenesis, including cell adhesion, migration, proliferation, differentiation and lumen formation. Specifically, fibronectin and laminins play decisive roles in blood vessel morphogenesis both during embryonic development and in pathological conditions, such as cancer.

GENERAL SIGNIFICANCE

Emerging evidence demonstrates the importance of ECM function during embryonic development, organ formation and tissue homeostasis. A wealth of data also illustrates the crucial role of the ECM in several human pathophysiological processes, including fibrosis, skeletal diseases, vascular pathologies and cancer. Notably, several ECM components have been identified as potential therapeutic targets for various diseases, including cancer. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

Prognostic significance of α5β1-integrin expression in cervical cancer

The purpose of this study was to evaluate the association of expression of α5β1-integrin with clinicopathologic features and prognosis in cervical cancer. Levels of α5β1-integrin in normal cervical mucosa and cervical cancer tissue were detected with immunohistochemistry. Survival analysis by the Kaplan-Meier method was performed to assess prognostic significance. α5β1-integrin expression was detected in 84.6% (143/169) cervical cancer samples, significantly different from that in normal cervical mucosa (P < 0.05). Positive expression rates of α5β1-integrin in patients with poor histologic differentiation, lymph node metastasis, and recurrence were elevated. Using Kaplan-Meier analysis, a comparison of survival curves of low versus high expression of α5β1-integrin revealed a highly significant difference in human cervical cancer cases (P < 0.05), suggesting that overexpression of α5β1-integrin is associated with a worse prognosis.The α5β1-integrin promotes angiogenesis and associates with lymph node metastasis, vascular invasion and poor prognosis of cervical cancer. The current study indicated that α5β1-integrin may be an independent prognostic factor for cervical cancer patients.

T11TS inhibits glioma angiogenesis by modulation of MMPs, TIMPs, with related integrin αv and TGF-β1 expressions

During glioma development, angiogenesis plays a crucial role in growth and vascularization of primary brain tumors. T11 target structure (T11TS), a bioactive molecule, has been documented as an anti-neoplastic agent in glioma-induced rats and also in human glioma in vitro. This novel molecule induces apoptosis of tumor cells by way of immune potentiation and impairs the glioma cell cycle, but its role in glioma angiogenesis has not been worked out in detail. Matrix metalloproteinases (MMPs) are enzymes promoting tumor angiogenesis by enzymatically remodeling the extracellular matrix and altering surface protein expression such as integrin αv and the matrix-bound proteins like TGF-β1. The present study was formulated to assess the efficacy of T11TS in the modulations of MMP-2 and -9 and their endogenous inhibitors (TIMP-1 and TIMP-2) as well as modulations of integrin αv and TGF-β1 in glioma-induced rats and also on the phenotypic markers of endothelial cells (CD31 and CD34). The parameters used were zymography, western blot, and flow cytometric analyses. It was observed that T11TS administration significantly downregulates the expression of matrix metalloproteinase-2 and -9 along with its ligand integrin αv and upregulates TIMP-1 and TIMP-2. In situ immunofluorescence and FACS results revealed that T11TS administration decreased the expression of the phenotypic markers (CD31/PECAM1, CD34), inhibiting the cell grip and also downregulating TGF-β1 expression (ELISA) from microglia cells in the glioma microenvironment. These results suggest that T11TS suppresses the expression of positive angiogenic growth factors and potentiates the expression of negative regulators in glioma-associated endothelial cells (ECs), resulting in an anti-angiogenic effect on glioma-induced angiogenesis.

Increased expression of α5β1-integrin is a prognostic marker for patients with gastric cancer

OBJECTIVE

The study was to evaluate the association of expression level of α5β1-integrin with clinicopathologic features and prognosis in gastric cancer (GC).

METHODS

The expression of α5β1-integrin in normal gastric mucosa and GC tissue was detected with immunohistochemistry. The level of α5 and β1 mRNA in GC tissues and non-neoplastic tissues was evaluated in 48 paired cases by quantitative real-time polymerase chain reaction (qRT-PCR). Survival analysis by the Kaplan-Meier method was performed to assess prognostic significance.

RESULTS

The α5β1-integrin expression was detected in 68.3 % (127/186) GC samples, and there was a significant difference on their positive expression rate between GC tissue and normal gastric mucosa (P < 0.001). The positive expression rate of α5β1-integrin in patients with poor histologic differentiation (P = 0.001), lymph node metastasis (P < 0.001), and recurrence (P < 0.001) group was heightened. Using Kaplan-Meier analysis, a comparison of survival curves of low versus high expresser of α5β1-integrin revealed a highly significant difference in human GC tissue (P = 0.002), which suggested that overexpression of α5β1-integrin is associated with a worse prognosis. Multivariate analyses showed that α5β1-integrin expression was independent risk factor predicting overall survival [Hazard ratio (HR) 1.594, 95 % confidence interval (CI) 1.236-2.408, P = 0.006] and disease-free survival [HR 3.952, 95 % CI 1.676-9.861, P = 0.003] in GC.

CONCLUSIONS

The α5β1-integrin promotes angiogenesis and associates with lymph node metastasis, vascular invasion and poor prognosis of GC. The current study shows that α5β1-integrin may be an independent prognostic factor for GC patients.

The role of the vessel wall

The role of the vessel wall is complex and its effects are wide-ranging. The vessel wall, specifically the endothelial monolayer that lines the inner lumen, possesses the ability to influence various physiological states both locally and systemically by controlling vascular tone, basement membrane component synthesis, angiogenesis, haemostatic properties, and immunogenicity. This is an overview of the function and structure of the vessel wall and how disruption and dysfunction in any of these regulatory roles can lead to disease states.

Deletion of Cdc42 enhances ADAM17-mediated vascular endothelial growth factor receptor 2 shedding and impairs vascular endothelial cell survival and vasculogenesis

Cdc42 is a Ras-related GTPase that plays an important role in the regulation of a range of cellular functions, including cell migration, proliferation, and survival. Consistent with its critical functions in vitro, the inactivation of Cdc42 in mice has been shown to result in embryonic lethality at embryonic day 6.5 (E6.5) before blood vessel formation. To determine the role of Cdc42 in new blood vessel formation, we have generated vascular endothelial cell (EC)-specific Cdc42 knockout mice by crossing Cdc42(flox/flox) mice with Tie2-Cre mice. The deletion of Cdc42 in ECs caused embryonic lethality with vasculogenesis and angiogenesis defects. We observed that Cdc42 is critical for EC migration and survival but not for cell cycle progression. Moreover, we found that the inactivation of Cdc42 in ECs decreased the level of vascular endothelial growth factor receptor 2 (VEGFR2) protein on the EC surface and promoted the production of a 75-kDa membrane-associated C-terminal VEGFR2 fragment. Using cultured primary mouse ECs and human umbilical vein ECs, we have demonstrated that the deletion of Cdc42 increased ADAM17-mediated VEGFR2 shedding. Notably, inhibition of ADAM17 or overexpression of VEGFR2 can partially reverse Cdc42 deletion-induced EC apoptosis. These data indicate that Cdc42 is essential for VEGFR2-mediated signal transduction in blood vessel formation.

A tumor-penetrating peptide modification enhances the antitumor activity of thymosin alpha 1

A serious limitation of numerous antitumor drugs is the incapacity to penetrate solid tumors. However, addition of an RGD fragment to peptide drugs might solve this problem. In this study, we explored whether the introduction of a permeability-enhancing sequence, such as iRGD (CRGDK/RGPD/EC) fragments, would enhance the activity of thymosin alpha 1 (Tα1). The modified Tα1 (Tα1-iRGD) was successfully expressed and purified, and the in vitro assay showed that Tα1-iRGD presented a similar activity as Tα1 in promoting proliferation of mouse splenocytes. Meanwhile, cell adhesion analysis revealed that Tα1-iRGD exhibited more specific and greater binding with tumor cells compared with Tα1. Furthermore, the iRGD fragment evidently enhanced the basal ability of Tα1 to inhibit proliferation of cancer cells in vitro, particularly of mouse melanoma cell line B16F10 and human lung cancer cell line H460. Our findings indicated that the addition of an iRGD fragment increased the anti-proliferative activity of Tα1 against cancer cells by improving the ability of Tα1 to penetrate the tumor cells. This study highlighted the important roles of an iRGD sequence in the therapeutic strategy of Tα1-iRGD. Thus, Tα1-iRGD could be a novel drug candidate for cancer treatment.

A urokinase receptor-derived peptide inhibiting VEGF-dependent directional migration and vascular sprouting

The receptor for the urokinase-type plasminogen activator (uPAR) is a widely recognized master regulator of cell migration, and uPAR₈₈₋₉₂ is the minimal sequence required to induce cell motility. We previously showed that soluble forms of uPAR elicit angiogenic responses through their uPAR₈₈₋₉₂ chemotactic sequence and that the synthetic peptide SRSRY exerts similar effects. By a drug design approach, based on the conformational analysis of the uPAR₈₈₋₉₂ sequence, we developed peptides (pERERY, RERY, and RERF) that potently inhibit signaling triggered by uPAR₈₈₋₉₂. In this study, we present evidence that these peptides are endowed also with a clear-cut antiangiogenic activity, although to different extents. The most active, RERF, prevents tube formation by human endothelial cells exposed to SRSRY. RERF also inhibits VEGF-triggered endothelial cell migration and cord-like formation in a dose-dependent manner, starting in the femtomolar range. RERF prevents F-actin polymerization, recruitment of αvβ3 integrin at focal adhesions, and αvβ3/VEGFR2 complex formation in endothelial cells exposed to VEGF. At molecular level, the inhibitory effect of RERF on VEGF signaling is shown by the decreased amount of phospho-FAK and phospho-Akt in VEGF-treated cells. In vivo, RERF prevents VEGF-dependent capillary sprouts originating from the host vessels that invaded angioreactors implanted in mice and neovascularization induced by subcorneal implantation of pellets containing VEGF in rabbits. Consistently, RERF reduced the growth and vascularization rate of tumors formed by HT1080 cells injected subcutaneously in the flanks of nude mice, indicating that RERF is a promising therapeutic agent for the control of diseases fuelled by excessive angiogenesis such as cancer.

Tetraspanin CD63 promotes vascular endothelial growth factor receptor 2-β1 integrin complex formation, thereby regulating activation and downstream signaling in endothelial cells in vitro and in vivo

CD63 is a member of the transmembrane-4 glycoprotein superfamily (tetraspanins) implicated in the regulation of membrane protein trafficking, leukocyte recruitment, and adhesion processes. We have investigated the involvement of CD63 in endothelial cell (EC) signaling downstream of β1 integrin and VEGF. We report that silencing of CD63 in primary ECs arrested capillary sprouting and tube formation in vitro because of impaired adhesion and migration of ECs. Mechanistically, CD63 associated with both β1 integrin and the main VEGF receptor on ECs, VEGFR2. Our data suggest that CD63 serves to bridge between β1 integrin and VEGFR2 because CD63 silencing disrupted VEGFR2-β1 integrin complex formation identified using proximity ligation assays. Signaling downstream of β1 integrin and VEGFR2 was attenuated in CD63-silenced cells, although their cell surface expression levels remained unaffected. CD63 was furthermore required for efficient internalization of VEGFR2 in response to VEGF. Importantly, systemic delivery of VEGF failed to potently induce VEGFR2 phosphorylation and downstream signaling in CD63-deficient mouse lungs. Taken together, our findings demonstrate a previously unrecognized role for CD63 in coordinated integrin and receptor tyrosine kinase signaling in vitro and in vivo.

SCUBE3 regulation of early lung cancer angiogenesis and metastatic progression

Signal peptide-CUB-EGF-like domain-containing protein 3 (SCUBE3) is strongly expressed in extremely invasive lung carcinoma. We showed in our previous study that SCUBE3 triggers the transforming growth factor-β pathway and subsequently promotes tumor angiogenesis and the epithelial-mesenchymal transition (EMT). However, the role of SCUBE3 in early tumor expansion hasn't been fully demonstrated in vivo. The present study used dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to temporally assess tumor angiogenesis in SCUBE3-knockdown and control non-small-cell lung carcinoma (NSCLC) cancer cells in the early tumor stage (weeks 1-3). We further evaluated the metastatic potential of the SCUBE3-knockdown and control tumor cells using a circulating tumor cell (CTC) assay. The differences in gene expression profile between these cell lines were determined using microarray analysis. The results show that SCUBE3 knockdown was associated with lower vascular permeability in the tumor and effectively inhibited the metastatic potential of NSCLC, as evidenced by the decreased CTCs in the mice bearing SCUBE3-knockdown tumors. Microarray analysis revealed that several genes involved in angiogenesis and EMT were down-regulated in SCUBE3-knockdown tumors, including matrix metalloproteinases (MMPs) 2, 9, and 14, (MMP-2, MMP-9, and MMP-14, respectively), fibronectin (FN-1), lysyl oxidase (LOX), hairy/enhancer-of-split related with YRPW motif protein 1 (HEY1), early growth response protein 1 (EGR1), and interleukin 8 (IL-8). Together these data suggest that SCUBE3 is a potential target for pharmacological intervention. The findings of the present study also show that differences in vascular permeability precede the CTCs detection, indicating that DCE-MRI may be a sensitive biomarker for assessing tumor invasiveness.

New insights into adhesion signaling in bone formation

Mineralized tissues that are protective scaffolds in the most primitive species have evolved and acquired more specific functions in modern animals. These are as diverse as support in locomotion, ion homeostasis, and precise hormonal regulation. Bone formation is tightly controlled by a balance between anabolism, in which osteoblasts are the main players, and catabolism mediated by the osteoclasts. The bone matrix is deposited in a cyclic fashion during homeostasis and integrates several environmental cues. These include diffusible elements that would include estrogen or growth factors and physicochemical parameters such as bone matrix composition, stiffness, and mechanical stress. Therefore, the microenvironment is of paramount importance for controlling this delicate equilibrium. Here, we provide an overview of the most recent data highlighting the role of cell-adhesion molecules during bone formation. Due to the very large scope of the topic, we focus mainly on the role of the integrin receptor family during osteogenesis. Bone phenotypes of some deficient mice as well as diseases of human bones involving cell adhesion during this process are discussed in the context of bone physiology.

VEGF-initiated angiogenesis and the uPA/uPAR system

Angiogenesis involves a series of tightly regulated cellular processes initiated primarily by the vascular endothelial growth factor (VEGF). The urokinase-type plasminogen activator system, consisting of the urokinase-type plasminogen activator (uPA), its cellular receptor uPAR and its inhibitor PAI-1, participates in the realization of these VEGF-induced processes by activating pericellular proteolysis, increasing vascular permeability and by supporting endothelial cell proliferation and migration.

α(V)β(3) integrin-targeted PLGA-PEG nanoparticles for enhanced anti-tumor efficacy of a Pt(IV) prodrug

Targeted delivery of therapeutics to tumor neovasculature is potentially a powerful approach for selective cancer treatment. Integrins are heterodimeric transmembrane proteins involved in cell adhesion and cell signaling, and their expression is commonly upregulated in cancers and inflammatory diseases. The α(v)β(3) integrin is differentially upregulated on angiogenic endothelial cells as well as on many cancer cells. Here we demonstrate the differential targeting of cisplatin prodrug-encapsulated poly(d,l-lactic-co-glycolic acid)-block-polyethylene glycol (PLGA-PEG) nanoparticles (NPs) to the α(v)β(3) integrin on cancer cells using the cyclic pentapeptide c(RGDfK). Cisplatin is one of the most widely used anticancer drugs, and approaches that can improve its therapeutic index are of broad importance. The RGD-targeted Pt(IV)-encapsulated NPs displayed enhanced cytotoxicity as compared to cisplatin administered in its conventional dosage form in model prostate and breast cancer epithelial cells in vitro. Cytotoxicities were also elevated in comparison to those of previously reported systems, a small molecule Pt(IV)-RGD conjugate and a Pt(IV) nanoscale coordination polymer carrying RGD moieties. This result encouraged us also to evaluate the anticancer effect of the new construct in an animal model. The RGD-targeted PLGA-PEG NPs were more efficacious and better tolerated by comparison to cisplatin in an orthotopic human breast cancer xenograft model in vivo.