Serum fibrosis markers could aid in the prediction of factor for successful oral antiviral treatment in hepatitis C.

BACKGROUND: It has been demonstrated that there may be a relationship between liver fibrosis and serum biomarkers. The aim of this study was to investigate pre- and postoral antiviral therapy levels of these biomarkers and their relationship with other fibrotic parameters in hepatitis C virus (HCV) patients. METHODS: The study group comprised HCV patients who were treated with oral antiviral regimens. Prior to, and 8 months after the treatment, serum biomarkers, including transforming growth factor-ß (TGF-ß), chitinase-3-like protein 1 (YKL-40), collagen type IV, matrix metalloproteinases (MMPs) and hyaluronic acid levels, were examined and fibrosis-4 (Fib-4) and aspartate aminotransferase to platelet ratio index (APRI) scores were calculated at the same times. RESULTS: In total, 45 HCV patients (aged between 27 and 86 years) participated. Of these 20 (44.4%) were cirrhotic and 25 (55.6%) were noncirrhotic. The concentrations of YKL-40 (P = 0.01) and TGF-ß (P = 0.032) after treatment were significantly higher than the pretreatment values, whereas hyaluronic acid concentrations decreased after treatment (P = 0.001). Noncirrhotic patients had significantly higher (P = 0.03) YKL-40 levels prior to therapy compared to cirrhotic patients. Median MMP-2 concentrations were higher in men than in women (P = 0.001). Prior to treatment, TGF-ß, YKL-40 and collagen type IV levels were negatively correlated with Fib-4 scores, whereas only TGF-ß and YKL-40 concentrations were negatively correlated with APRI scores. CONCLUSION: YKL-40, TGF ß and hyaluronic acid may be markers for fibrotic change during oral therapy for HCV. In particular, TGF ß concentrations correlated with fibrotic indices. However, these results should be confirmed and validated by further research.

Preventive Effect of Canstatin against Ventricular Arrhythmia Induced by Ischemia/Reperfusion Injury: A Pilot Study.

Ventricular arrhythmia induced by ischemia/reperfusion (I/R) injury is a clinical problem in reperfusion therapies for acute myocardial infarction. Ca2+ overload through reactive oxygen species (ROS) production is a major cause for I/R-induced arrhythmia. We previously demonstrated that canstatin, a C-terminal fragment of type IV collagen α2 chain, regulated Ca2+ handling in rat heart. In this study, we aimed to clarify the effects of canstatin on I/R-induced ventricular arrhythmia in rats. Male Wistar rats were subjected to I/R injury by ligating the left anterior descending artery followed by reperfusion. Ventricular arrhythmia (ventricular tachycardia and ventricular fibrillation) was recorded by electrocardiogram. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity and ROS production in neonatal rat cardiomyocytes (NRCMs) stimulated with oxygen glucose deprivation/reperfusion (OGD/R) were measured by lucigenin assay and 2',7'-dichlorodihydrofluorescein diacetate staining, respectively. The H2O2-induced intracellular Ca2+ ([Ca2+]i) rise in NRCMs was measured by a fluorescent Ca2+ indicator. Canstatin (20 µg/kg) inhibited I/R-induced ventricular arrhythmia in rats. Canstatin (250 ng/mL) inhibited OGD/R-induced NOX activation and ROS production and suppressed the H2O2-induced [Ca2+]i rise in NRCMs. We for the first time demonstrated that canstatin exerts a preventive effect against I/R-induced ventricular arrhythmia, perhaps in part through the suppression of ROS production and the subsequent [Ca2+]i rise.

Decreased Expression of Canstatin in Rat Model of Monocrotaline-Induced Pulmonary Arterial Hypertension: Protective Effect of Canstatin on Right Ventricular Remodeling.

Pulmonary arterial hypertension (PAH) is a progressive disease which causes right ventricular (RV) failure. Canstatin, a C-terminal fragment of type IV collagen α2 chain, is expressed in various rat organs. However, the expression level of canstatin in plasma and organs during PAH is still unclear. We aimed to clarify it and further investigated the protective effects of canstatin in a rat model of monocrotaline-induced PAH. Cardiac functions were assessed by echocardiography. Expression levels of canstatin in plasma and organs were evaluated by enzyme-linked immunosorbent assay and Western blotting, respectively. PAH was evaluated by catheterization. RV remodeling was evaluated by histological analyses. Real-time polymerase chain reaction was performed to evaluate RV remodeling-related genes. The plasma concentration of canstatin in PAH rats was decreased, which was correlated with a reduction in acceleration time/ejection time ratio and an increase in RV weight/body weight ratio. The protein expression of canstatin in RV, lung and kidney was decreased in PAH rats. While recombinant canstatin had no effect on PAH, it significantly improved RV remodeling, including hypertrophy and fibrosis, and prevented the increase in RV remodeling-related genes. We demonstrated that plasma canstatin is decreased in PAH rats and that administration of canstatin exerts cardioprotective effects.

Suppression of Ocular Vascular Inflammation through Peptide-Mediated Activation of Angiopoietin-Tie2 Signaling.

Persistent inflammation is a complication associated with many ocular diseases. Changes in ocular vessels can amplify disease responses and contribute to vision loss by influencing the delivery of leukocytes to the eye, vascular leakage, and perfusion. Here, we report the anti-inflammatory activity for AXT107, a non-RGD, 20-mer αvß3 and α5ß1 integrin-binding peptide that blocks vascular endothelial growth factor (VEGF)-signaling and activates tyrosine kinase with immunoglobulin and EGF-like domains 2 (Tie2) using the normally inhibitory ligand angiopoietin 2 (Ang2). Tumor necrosis factor α (TNFα), a central inflammation mediator, induces Ang2 release from endothelial cells to enhance its stimulation of inflammation and vascular leakage. AXT107 resolves TNFα-induced vascular inflammation in endothelial cells by converting the endogenously released Ang2 into an agonist of Tie2 signaling, thereby disrupting both the synergism between TNFα and Ang2 while also preventing inhibitor of nuclear factor-κB α (IκBα) degradation directly through Tie2 signaling. This recovery of IκBα prevents nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) nuclear localization, thereby blocking NF-κB-induced inflammatory responses, including the production of VCAM-1 and ICAM-1, leukostasis, and vascular leakage in cell and mouse models. AXT107 also decreased the levels of pro-inflammatory TNF receptor 1 (TNFR1) without affecting levels of the more protective TNFR2. These data suggest that AXT107 may provide multiple benefits in the treatment of retinal/choroidal and other vascular diseases by suppressing inflammation and promoting vascular stabilization.

T7 peptide cytotoxicity in human hepatocellular carcinoma cells is mediated by suppression of autophagy.

The T7 peptide, an active fragment of full­length tumstatin [the non­collagenous 1 domain of the type IV collagen α3 chain, α3 (IV) NC1], has exhibited potential antitumor effects in several types of cancer cells. However, the mechanism underlying its action against human hepatocellular carcinoma (HCC) remains unclear. The present study aimed to investigate the role of autophagy in T7 peptide­induced cytotoxicity in HCC cells in vitro and in vivo. The results revealed that the T7 peptide significantly reduced cell viability and induced cell cycle arrest in HCC cells. The T7 peptide induced apoptosis in HCC cells through upregulation of Bax, Fas, and Fas ligand, and through upregulation of the anti­apoptotic protein Bcl­2. In addition, treatment with the T7 peptide induced protective autophagy in HCC cells. Blocking autophagy by 3­methyladenineor bafilomycin A1 enhanced T7 peptide­induced apoptosis. Furthermore, co­treatment with MK­2206 (an Akt specific inhibitor) or rapamycin (an inhibitor of mTOR) enhanced T7 peptide­induced autophagy, whereas co­treatment with insulin (an activator of the Akt/mTOR signaling pathway) alleviated T7 peptide­induced autophagy, which suggested that the T7 peptide may induce autophagy activation via inhibition of the Akt/mTOR signaling pathway. Taken together, the present results demonstrated that suppression of autophagy potentiated the cytotoxic effects of the T7 peptide, and suggested that the T7 peptide may serve as a potential alternative compound for HCC therapy.

A collagen IV-derived peptide disrupts α5ß1 integrin and potentiates Ang2/Tie2 signaling.

The angiopoietin (Ang)/Tie2 signaling pathway is essential for maintaining vascular homeostasis, and its dysregulation is associated with several diseases. Interactions between Tie2 and α5ß1 integrin have emerged as part of this control; however, the mechanism is incompletely understood. AXT107, a collagen IV-derived peptide, has strong antipermeability activity and has enabled the elucidation of this previously undetermined mechanism. Previously, AXT107 was shown to inhibit VEGFR2 and other growth factor signaling via receptor tyrosine kinase association with specific integrins. AXT107 disrupts α5ß1 and stimulates the relocation of Tie2 and α5 to cell junctions. In the presence of Ang2 and AXT107, junctional Tie2 is activated, downstream survival signals are upregulated, F-actin is rearranged to strengthen junctions, and, as a result, endothelial junctional permeability is reduced. These data suggest that α5ß1 sequesters Tie2 in nonjunctional locations in endothelial cell membranes and that AXT107-induced disruption of α5ß1 promotes clustering of Tie2 at junctions and converts Ang2 into a strong agonist, similar to responses observed when Ang1 levels greatly exceed those of Ang2. The potentiation of Tie2 activation by Ang2 even extended to mouse models in which AXT107 induced Tie2 phosphorylation in a model of hypoxia and inhibited vascular leakage in an Ang2-overexpression transgenic model and an LPS-induced inflammation model. Because Ang2 levels are very high in ischemic diseases, such as diabetic macular edema, neovascular age-related macular degeneration, uveitis, and cancer, targeting α5ß1 with AXT107 provides a potentially more effective approach to treat these diseases.

Enhanced blood-brain barrier penetration and glioma therapy mediated by T7 peptide-modified low-density lipoprotein particles.

Therapeutic outcome for the treatment of glioma was often limited due to the non-targeted nature and low permeability of drugs across the blood-brain barrier (BBB). An ideal glioma-targeted delivery system need to traverse the BBB and then target glioma cells with adequate optimized physiochemical properties and biocompatibility. However, it is an enormous challenge to the researchers to engineer the above-mentioned features into a single nanocarrier particle. New frontiers in nanomedicine are advancing the research of new biomaterials. In this study, we demonstrate a strategy for glioma targeting by encapsulating vincristine sulfate (VCR) into a naturally available low-density lipoprotein particles (LDL)-based drug delivery system with the modification of T7 peptide ligand (T7-LDL). LDL, endogenous lipid transporters, can specifically bind to brain endothelial cells and glioma cells via interacting with the low-density lipoprotein receptors (LDLR). T7 is a seven-peptide ligand of transferrin receptors (TfR) capable of circumventing the BBB and then targeting glioma. By combining the dual-targeting delivery effect of T7 peptide and parent LDL, T7-LDL displayed higher glioma localization than that of parent LDL. After loading with VCR, T7-LDL showed the most favorable antiglioma effect in vitro and in vivo. These results demonstrated that T7-LDL is an important potential drug delivery system for glioma-targeted therapy.

Nodular lesions in diabetic nephropathy: Collagen staining and renal prognosis.

AIMS: Nodular lesions are one of the most characteristic pathological changes of advanced diabetic nephropathy (DN). Previous studies have demonstrated that the pattern of both routine and collagen staining of nodular lesions changes during their development. However, the association between such changes of staining and the renal prognosis remains unclear. METHODS: Among 252 patients with biopsy-proven DN, 67 met the selection criteria and were enrolled to investigate this relationship. In all patients, nodular lesions were stained with periodic acid Schiff, periodic acid methenamine silver, and Masson trichrome stains, and immunostaining was done for type I, III, IV, V, and VI collagen. The endpoint was commencement of dialysis due to end-stage renal disease. RESULTS: At least one mesangiolytic nodular lesion (MNL) that showed faint staining for PAS and PAM was found in 61% of the patients. MNLs were negative for type IV collagen staining, unlike the strong positivity of non-MNLs, while type V and VI collagen staining were strongly positive in all nodular lesions. Cox proportional hazards regression analysis revealed that the hazard ratio (HR) for the endpoint was significantly higher in patients with at least one MNL than in patients with no MNLs after adjustment for known promoters of renal progression (HR: 2.94; 95% confidence interval: 1.24-7.07). CONCLUSIONS: MNLs may reflect characteristic differences of collagen production and could be a useful prognostic indicator in patients with nodular lesions. Further investigation of the mechanism underlying these differences of collagen production could contribute to finding new therapeutic targets for DN.

Use of Ovine-based Collagen Extracellular Matrix and Gentian Violet/Methylene Blue Antibacterial Foam Dressings to Help Improve Clinical Outcomes in Lower Extremity Wounds: A Retrospective Cohort Study.

Dressings that provide broad spectrum metalloprotease reduction along with inherent aspects of an extracellular matrix may contribute to improved wound healing outcomes and shorter treatment times. OBJECTIVE: The author performed a retrospective case series analysis to determine the clinical outcomes of regular debridement with the use of ovine-based collagen extracellular matrix dressings and gentian violet/methylene blue polyurethane antibacterial foam dressings in treating 53 patients with 53 chronic lower extremity wounds (diabetic foot ulcers [DFUs], venous leg ulcers, and heel pressure ulcers). MATERIALS AND METHODS: Patients were treated twice weekly in an outpatient clinic for the first 4 weeks and weekly thereafter until closure. RESULTS: Average body mass index (BMI) for the study population was 28.3, and the average patient age was 75.9 years. Mean percent wound surface area reduction at 4, 8, and 12 weeks was 38.5%, 73.3%, and 91.3%, respectively. Average time to closure for all wounds was 10.6 weeks (range, 5-24 weeks). All wounds were 100% reepithelialized by week 20 except 1 DFU that reepithelialized at week 24. The average cost of care for a single wound episode (from presentation to closure) was $2749.49. CONCLUSION: Results of this analysis showed that the healing of chronic wounds in this series could be achieved at a reasonable cost with regular debridement and a collagen matrix dressing regimen, even in patients of advanced age and above average BMI as well as in wounds that did not achieve > 40% wound surface area reduction at 4 weeks.

Tyrosine kinase blocking collagen IV-derived peptide suppresses ocular neovascularization and vascular leakage.

Vascular endothelial growth factor (VEGF)-neutralizing proteins provide benefit in several retinal and choroidal vascular diseases, but some patients still experience suboptimal outcomes, and the need for frequent intraocular injections is a barrier to good outcomes. A mimetic peptide derived from collagen IV, AXT107, suppressed subretinal neovascularization (NV) in two mouse models predictive of effects in neovascular age-related macular degeneration (NVAMD) and inhibited retinal NV in a model predictive of effects in ischemic retinopathies. A combination of AXT107 and the current treatment aflibercept suppressed subretinal NV better than either agent alone. Furthermore, AXT107 caused regression of choroidal NV. AXT107 reduced the VEGF-induced vascular leakage that underlies macular edema in ischemic retinopathies and NVAMD. In rabbit eyes, which are closer to the size of human eyes, intraocular injection of AXT107 significantly reduced VEGF-induced vascular leakage by 86% at 1 month and 70% at 2 months; aflibercept significantly reduced leakage by 69% at 1 month and did not reduce leakage at 2 months, demonstrating the longer effectiveness of AXT107. AXT107 reduced ligand-induced phosphorylation of multiple receptors: VEGFR2, c-Met, and PDGFRß. Optimal signaling through these receptors requires complex formation with ß3 integrin, which was reduced by AXT107 binding to αvß3 AXT107 also reduced total VEGFR2 levels by increasing internalization, ubiquitination, and degradation. This biomimetic peptide is a sustained, multitargeted therapy that may provide advantages over intraocular injections of specific VEGF-neutralizing proteins.

Systemic delivery of siRNA by T7 peptide modified core-shell nanoparticles for targeted therapy of breast cancer.

Systemic delivery of siRNA is the most challenging step to transfer RNAi to clinical application for breast cancer therapy. In this study, the tumor targeted, T7 peptide modified core-shell nanoparticles (named as T7-LPC/siRNA NPs) were constructed to achieve effective systemic delivery of siRNA. The core-shell structure of T7-LPC/siRNA NPs enables them to encapsulate siRNA in the core and protect it from RNase degradation during circulation. In vitro cellular uptake and gene silencing experiments demonstrated that T7-LPC/siEGFR NPs could deliver EGFR siRNA into breast cancer cells through receptor mediated endocytosis and effectively down-regulate the EGFR expression. In vivo distribution study proved the T7-LPC/siRNA NPs could deliver fluorescence labeled siRNA to the tumor site more efficiently than the non-targeted PEG-LPC/siRNA NPs after intravenous administration. Furthermore, the experiments of in vivo tumor therapy confirmed that intravenous administration of T7-LPC/siEGFR NPs led to an effective EGFR down-regulation and an obvious inhibition of breast tumor growth, with little activation of immune responses and negligible body weight loss. These results suggested that T7-LPC/siRNA NPs could be an effective and safe systemic siRNA delivery system for RNAi-based breast cancer therapy.

Dual targeted nanocarrier for brain ischemic stroke treatment.

Focal cerebral ischemia, known as stroke, causes serious long-term disabilities globally. Effective therapy for cerebral ischemia demands a carrier that can penetrate the blood-brain barrier (BBB) and subsequently target the ischemia area in brain. Here, we designed a novel neuroprotectant (ZL006) loaded dual targeted nanocarrier based on liposome (T7&SHp-P-LPs/ZL006) conjugated with T7 peptide (T7) and stroke homing peptide (SHp) for penetrating BBB and targeting ischemia area, respectively. Compared with non-targeting liposomes, T7&SHp-P-LPs/ZL006 could transport across BCEC cells and significantly enhance cellular uptake and reduce cells apoptosis of excitatory amino acid stimulated PC-12 cells. However, there was no significant difference in cellular uptake between SHp-modified and plain liposomes when PC-12 cells were incubated without excitatory amino acid. Besides, ex vivo fluorescent images indicated that DiR labeled T7&SHp-P-LPs could efficiently transport across BBB and mostly accumulated in ischemic region rather than normal cerebral hemisphere of MCAO rats. Furthermore, T7&SHp-P-LPs/ZL006 could enhance the ability of in vivo anti-ischemic stroke of MCAO rats. These results demonstrated that T7&SHp-P-LPs could be used as a safe and effective dual targeted nanocarrier for ischemic stroke treatment.

[Investigation of possible approaches to angiogenesis regulation in vitro with the help of recombinant fragments of angiogenesis inhibitors such as endostatin, tumstatin and PEDF].

Neovascular diseases of visual organ such as age-related macular degeneration, retinopathy of prematurity, diabetic retinopathy, thrombosis of central retina vein and its branches, neovascular glaucoma, choroid and retina tumors have the leading positions in the list of ophtalmopatologies that result in blindness and incapacity. The variety of angiostatic medications of applied ophtalmology is scant. The aim of work was to study the possibile approaches to angiogenesis regulation in vitro with the help of recombinant fragments of natural inhibitors of angiogenesis such as endostatin, tumstatin and PEDF (pigment epithelial derived factor), and also theirability to be the base of potentially feasible and pharmacologically active substances. It is determined that endostatin, tumstatin and PEDF, as well as the comparison medication Bevacizumab in vitro have pro-or antiangiogenic influence. The direction of the biological effect depends on the cultivation conditions, peptide concentration in the cultural fluid and stage of angiogenesis.

Arresten, a collagen-derived angiogenesis inhibitor, suppresses invasion of squamous cell carcinoma.

The turnover of extracellular matrix liberates various cryptic molecules with novel biological activity. Among these are the collagen-derived anti-angiogenic fragments, some of which are suggested to affect carcinoma cells also directly. Arresten is an endogenous angiogenesis inhibitor that is derived from the non-collagenous domain of the basement membrane collagen IV α1 chain. As the mere prevention of tumor angiogenesis leads to hypoxia that can result in selection of more aggressive cell types and reduces the efficacy of chemotherapy, we aimed here to elucidate how arresten influences the aggressive human carcinoma cells. Arresten efficiently inhibited migration and invasion of HSC-3 tongue carcinoma cells in culture and in an organotypic model. Subcutaneous Arr-HSC xenografts grew markedly more slowly in nude mice and showed reduced tumor cell proliferation, vessel density and local invasiveness. In the organotypic assay, HSC-3 cells overproducing arresten (Arr-HSC) showed induction of cell death. In monolayer culture the Arr-HSC cells grew in aggregated cobblestone-like clusters and, relative to the control cells, showed increased expression and localization of epithelial marker E-cadherin in cell-cell contacts. Application of electric cell-substrate impedance sensing (ECIS) further supported our observations on altered morphology and motility of the Arr-HSC cells. Administration of a function-blocking α1 integrin antibody abolished the impedance difference between the Arr-HSC and control cells suggesting that the effect of arresten on promotion of HSC-3 cell-cell contacts and cell spreading is at least partly mediated by α1ß1 integrin. Collectively, our data suggest novel roles for arresten in the regulation of oral squamous carcinoma cell proliferation, survival, motility and invasion through the modulation of cell differentiation state and integrin signaling.

Collagen IV and CXC chemokine-derived antiangiogenic peptides suppress glioma xenograft growth.

Peptides are receiving increasing attention as therapeutic agents due to their high binding specificity and versatility to be modified as targeting or carrier molecules. Particularly, peptides with antiangiogenic activity are of high interest because of their applicability to a wide range of cancers. In this study, we investigate the biological activity of two novel antiangiogenic peptides in preclinical glioma models. One peptide SP2000 is derived from collagen IV and the other peptide SP3019 belongs to the CXC family. We have previously characterized the capacity of SP2000 and SP3019 to inhibit multiple biological endpoints linked to angiogenesis in human endothelial cells in several assays. Here, we report additional studies using endothelial cells and focus on the activity of these peptides against human glioma cell growth, migration and adhesion in vitro, and growth as tumor xenografts in vivo. We found that SP2000 completely inhibits migration of the glioma cells at 50 µmol/l and SP3019 produced 50% inhibition at 100 µmol/l. Their relative antiadhesion activities were similar, with SP2000 and SP3019 generating 50% adhesion inhibition at 4.9 ± 0.82 and 21.3 ± 5.92 µmol/l, respectively. In-vivo glioma growth inhibition was 63% for SP2000 and 76% for SP3019 after 2 weeks of administration at daily doses of 10 and 20 mg/kg, respectively. The direct activity of these peptides against glioma cells in conjunction with their antiangiogenic activities warrants their further development as either stand-alone agents or in combination with standard cytotoxic or emerging targeted therapies in malignant brain tumors.

Antiangiogenic and antivascular effects of a recombinant tumstatin-derived peptide in a corneal neovascularization model.

Tumstatin, a cleavage fragment of collagen IV, is a potent endogenous inhibitor of angiogenesis. Tumstatin-derived peptide T8 possesses all angiostatic properties of full-length tumstatin and indirectly suppresses tumor growth. The potential of T8 to block pathological angiogenesis in the eye has not been explored yet. Here we assess antiangiogenic effects of a recombinant T8 peptide in rabbit corneal neovascularization models. The fusion protein consisting of T8 and thioredoxin was synthesized in a highly efficient Escherichia coli expression system, isolated using ion-exchange chromatography and cleaved with TEV (tobacco etch virus) protease. The target peptide was purified on an anion-exchange resin and by reversed phase high-performance liquid chromatography. The recombinant peptide suppressed the proliferation of basic fibroblast growth factor-induced SVEC-4-10 endothelial cells (simian virus 40-immortalized murine endothelial cells) and inhibited tube formation in these cells in a dose-dependent manner. In rabbit corneal neovascularization models T8 demonstrated the ability to prevent pathological angiogenesis (when injected simultaneously with the induction of neovascularization) and, moreover, to promote the regression of newly-formed blood vessels (when injected on day 8 after angiogenesis stimulation). Our results suggest that T8 may have a therapeutic potential in the treatment of ocular neovascular diseases.

Inhibitory effect of canstatin in alkali burn-induced corneal neovascularization.

OBJECTIVE: To examine the effect of recombinant canstatin protein on the corneal neovascularization (CorNV) in an alkaline burn-induced CorNV model. METHODS: This study involved 50 C57BL/6 mice. CorNV was induced by an alkaline burn of the corneas with 1 N NaOH under general anesthesia. Beginning 24 h after CorNV induction, recombinant canstatin protein was administered intraperitoneally at 5 or 10 mg/kg body weight once a day for up to 14 days. CorNV was evaluated by slit-lamp microscopy. Growth factors and cytokines relating to neovascularization and inflammation in the corneas were evaluated by real-time polymerase chain reaction (RT-PCR), Western blotting, immunohistochemistry or ELISA. RESULTS: Recombinant canstatin protein significantly inhibited CorNV. Compared to the untreated or PBS-treated CorNV group, expression of vascular endothelial growth factor (VEGF) markedly decreased in the canstatin-treated group as detected by various methods. Western blotting and RT-PCR showed that the canstatin treatment inhibited the expression of hypoxia-inducible factor and VEGF. Day 7 revealed the greatest changes: ELISA assay showed that TNF-α also significantly decreased in canstatin-treated corneas. CONCLUSIONS: Recombinant canstatin protein suppressed experimental CorNV, suggesting that canstatin may serve as a useful angiogenic inhibitor for the treatment of neovascularization-related corneal diseases.

Identification of amino acids essential for the antiangiogenic activity of tumstatin and its use in combination antitumor activity.

Tumstatin is an angiogenesis inhibitor that binds to alphavbeta3 integrin and suppresses tumor growth. Previous deletion mutagenesis studies identified a 25-aa fragment of tumstatin (tumstatin peptide) with in vitro antiangiogenic activity. Here, we demonstrate that systemic administration of this tumstatin peptide inhibits tumor growth and angiogenesis. Site-directed mutagenesis identified amino acids L, V, and D as essential for the antiangiogenic activity of tumstatin. The tumstatin peptide binds to alphavbeta3 integrin on proliferating endothelial cells and localizes to select tumor endothelium in vivo. Using 3D molecular modeling, we identify a putative interaction interface for tumstatin peptide on alphavbeta3 integrin. The antitumor activity of the tumstatin peptide, in combination with bevacizumab (anti-VEGF antibody), displays significant improvement in efficacy against human renal cell carcinoma xenografts when compared with the single-agent use. Collectively, our results demonstrate that tumstatin peptide binds specifically to the tumor endothelium, and its antiangiogenic action is mediated by alphavbeta3 integrin, and, in combination with an anti-VEGF antibody it exhibits enhanced tumor suppression of renal cell carcinoma.

Inhibition of tumor angiogenesis by tumstatin: insights into signaling mechanisms and implications in cancer regression.

Growing tumors develop additional new blood vessels to meet the demand for adequate nutrients and oxygen, a process called angiogenesis. Cancer is a highly complex disease promoted by excess angiogenesis; interfering with this process poses for an attractive approach for controlling tumor growth. This hypothesis led to the identification of endogenous angiogenesis inhibitors generated from type IV collagen, a major component of vascular basement membrane (VBM). Type IV collagen and the angiogenesis inhibitors derived from it are involved in complex roles, than just the molecular construction of basement membranes. Protease degradation of collagens in VBM occurs in various physiological and pathological conditions and produces several peptides. Some of these peptides are occupied in the regulation of functions conflicting from those of their original integral molecules. Tumstatin (alpha3(IV)NC1), a proteolytic C-terminal non-collagenous (NC1) domain from type IV collagen alpha3 chain has been highlighted recently because of its potential role in anti-angiogenesis, however its biological actions are not limited to these processes. alpha3(IV)NC1 inhibits proliferation by promoting endothelial cell apoptosis and suppresses diverse tumor angiogenesis, thus making it a potential candidate for future cancer therapy. The present review surveys the physiological functions of type IV collagen and discovery of alpha3(IV)NC1 as an antiangiogenic protein with a comprehensive overview of the knowledge gained by us towards understanding its signaling mechanisms.

Peritumor injections of purified tumstatin delay tumor growth and lymphatic metastasis in an orthotopic oral squamous cell carcinoma model.

Tumstatin - non-collagenous (NC1) domain of the alpha 3 chain of type IV collagen - is a potent inhibitor of tumor angiogenesis. Successful tumor inhibition has been reported in glioma, bronchopulmonary cancer and melanoma experimental model. In this study, the effects of tumstatin, in vitro and in vivo, were investigated in an oral cancer model. Recombinant human tumstatin proteins were obtained by the transformation of Tn 5B1-4 cells, transfected with a plasmid containing tumstatin cDNA using the lipofection method, as previously described. Tumstatin inhibited the proliferation of human umbilical vascular endothelial cells in a dose dependent manner in a proliferation assay. For the in vivo analysis, we established an orthotopic oral squamous cell carcinoma (AT-84 cells) animal (C3H/He) model. In this animal model, the in vivo inhibitory effects of tumstatin on the tumor growth and on the metastasis of tumors were demonstrated. However, the tumors did not show complete remission. Immunostaining of the tumor microvessels (CD-31/PECAM) revealed that the density of tumor microvessels was significantly decreased in the tumstatin treated primary tumors. The results demonstrated that tumstatin delayed the tumor growth and the metastasis of oral squamous cell carcinomas. However, tumstatin alone failed to achieve tumor regression. Therefore, tumstatin might have an adjuvant role in the treatment of oral cancers, in combination with the conventional therapy.