Notch1 and Notch4 core binding domain peptibodies exhibit distinct ligand-binding and anti-angiogenic properties

The Notch signaling pathway is an important therapeutic target for the treatment of inflammatory diseases and cancer. We previously created ligand-specific inhibitors of Notch signaling comprised of Fc fusions to specific EGF-like repeats of the Notch1 extracellular domain, called Notch decoys, which bound ligands, blocked Notch signaling, and showed anti-tumor activity with low toxicity. However, the study of their function depended on virally mediated expression, which precluded dosage control and limited clinical applicability. We have refined the decoy design to create peptibody-based Notch inhibitors comprising the core binding domains, EGF-like repeats 10-14, of either Notch1 or Notch4. These Notch peptibodies showed high secretion properties and production yields that were improved by nearly 100-fold compared to previous Notch decoys. Using surface plasmon resonance spectroscopy coupled with co-immunoprecipitation assays, we observed that Notch1 and Notch4 peptibodies demonstrate strong but distinct binding properties to Notch ligands DLL4 and JAG1. Both Notch1 and Notch4 peptibodies interfere with Notch signaling in endothelial cells and reduce expression of canonical Notch targets after treatment. While prior DLL4 inhibitors cause hyper-sprouting, the Notch1 peptibody reduced angiogenesis in a 3-dimensional in vitro sprouting assay. Administration of Notch1 peptibodies to neonate mice resulted in reduced radial outgrowth of retinal vasculature, confirming anti-angiogenic properties. We conclude that purified Notch peptibodies comprising EGF-like repeats 10-14 bind to both DLL4 and JAG1 ligands and exhibit anti-angiogenic properties. Based on their secretion profile, unique Notch inhibitory activities, and anti-angiogenic properties, Notch peptibodies present new opportunities for therapeutic Notch inhibition.

ScFvs as Allosteric Inhibitors of VEGFR-2: Novel Tools to Harness VEGF Signaling

Vascular Endothelial Growth Factor Receptor 2 (VEGFR-2) is the main mediator of angiogenic signaling in endothelial cells and a primary responder to VEGF. VEGF dependent VEGFR-2 activation regulates endothelial cell migration and proliferation, as well as vessel permeability. VEGF is presented as an antiparallel homodimer, and its binding to VEGFR-2 brings two receptors in close proximity. Downstream signaling is triggered by receptor dimerization, kinase activation, and receptor internalization. Our aim was to further investigate allosteric inhibition using binders targeting extracellular subdomains 4⁻7 of VEGFR-2 as an alternative to existing anti-angiogenic therapies, which rely on neutralizing VEGF or blocking of the ligand-binding site on the receptor. We applied phage display technology to produce single chain antibody fragments (scFvs) targeting VEGFR-2. Selected antibody fragments were characterized using biophysical and biological assays. We characterized several antibody fragments, which exert their inhibitory effect of VEGFR-2 independent of ligand binding. These reagents led to rapid clearance of VEGFR-2 from the cell surface without kinase activation, followed by an increase in intracellular receptor-positive vesicles, suggesting receptor internalization. Our highly specific VEGFR-2 binders thus represent novel tools for anti-angiogenic therapy and diagnostic applications.

Generation of Expression Plasmids for Angiostatin, Endostatin and Timp-2 for Cancer Gene Therapy

Antiangiogenic therapy may represent a promising approach to cancer treatment. Indeed, the efficacy of endogenous angiogenesis inhibitors, including angiostatin, endostatin and TIMPs, has been demonstrated in many types of solid tumors in animal models. In view of the possible problems associated with long-term administration of inhibitors as recombinant proteins, we propose their delivery as nucleic acids through a gene therapy approach. To this end, eukaryotic expression constructs for murine angiostatin and endostatin as well as human TIMP-2 were generated, and characterized in vitro. All constructs carry the relevant cDNAs under the control of the strong HCMV promoter/enhancer, and cleavable leader signals to allow protein secretion. Expression of the angiogenesis inhibitors was detected by in vitro transcription/translation experiments as well as transfection of 293T cells, followed by Western blotting (WB) or radioimmunoprecipitation analysis of both cell lysates and supernatants (SNs). These constructs might be used for in vivo intramuscular delivery of plasmid DNA and as a set of reagents for the development of retroviral as well as adeno-associated viral (AAV) vectors expressing angiogenesis inhibitors.

AAV-mediated gene delivery of the calreticulin anti-angiogenic domain inhibits ocular neovascularization

Ocular neovascularization is a common pathological feature in diabetic retinopathy and neovascular age-related macular degeneration that can lead to severe vision loss. We evaluated the therapeutic efficacy of a novel endogenous inhibitor of angiogenesis, the calreticulin anti-angiogenic domain (CAD180), and its functional 112-residue fragment, CAD-like peptide 112 (CAD112), delivered using a self-complementary adeno-associated virus serotype 2 (scAAV2) in rodent models of oxygen-induced retinopathy and laser-induced choroidal neovascularization. The expression of CAD180 and CAD112 was elevated in human umbilical vein endothelial cells transduced with scAAV2-CAD180 or scAAV2-CAD112, respectively, and both inhibited angiogenic activity in vitro. Intravitreal gene delivery of scAAV2-CAD180 or scAAV2-CAD112 significantly inhibited ischemia-induced retinal neovascularization in rat eyes (CAD180: 52.7% reduction; CAD112: 49.2% reduction) compared to scAAV2-mCherry, as measured in retinal flatmounts stained with isolectin B4. Moreover, the retinal structure and function were unaffected by scAAV2-CAD180 or scAAV2-CAD112, as measured by optical coherence tomography and electroretinography. Moreover, subretinal delivery of scAAV2-CAD180 or scAAV2-CAD112 significantly attenuated laser-induced choroidal neovascularization in mouse eyes compared to scAAV2-mCherry, as measured by fundus fluorescein angiography (CAD180: 62.4% reduction; CAD112: 57.5% reduction) and choroidal flatmounts (CAD180: 40.21% reduction; CAD112: 43.03% reduction). Gene delivery using scAAV2-CAD180 or scAAV2-CAD112 has significant potential as a therapeutic option for the management of ocular neovascularization.

Intravitreous injection of AAV2-sFLT01 in patients with advanced neovascular age-related macular degeneration: a phase 1, open-label trial

BACKGROUND

Long-term intraocular injections of vascular endothelial growth factor (VEGF)-neutralising proteins can preserve central vision in many patients with neovascular age-related macular degeneration. We tested the safety and tolerability of a single intravitreous injection of an AAV2 vector expressing the VEGF-neutralising protein sFLT01 in patients with advanced neovascular age-related macular degeneration.

METHODS

This was a phase 1, open-label, dose-escalating study done at four outpatient retina clinics in the USA. Patients were assigned to each cohort in order of enrolment, with the first three patients being assigned to and completing the first cohort before filling positions in the following treatment groups. Patients aged 50 years or older with neovascular age-related macular degeneration and a baseline best-corrected visual acuity score of 20/100 or less in the study eye were enrolled in four dose-ranging cohorts (cohort 1, 2 × 10⁸ vector genomes (vg); cohort 2, 2 × 10⁹ vg; cohort 3, 6 × 10⁹ vg; and cohort 4, 2 × 10¹⁰ vg, n=3 per cohort) and one maximum tolerated dose cohort (cohort 5, 2 × 10¹⁰ vg, n=7) and followed up for 52 weeks. The primary objective of the study was to assess the safety and tolerability of a single intravitreous injection of AAV2-sFLT01, through the measurement of eye-related adverse events. This trial is registered with ClinicalTrials.gov, number NCT01024998.

FINDINGS

19 patients with advanced neovascular age-related macular degeneration were enrolled in the study between May 18, 2010, and July 14, 2014. All patients completed the 52-week trial period. Two patients in cohort 4 (2 × 10¹⁰ vg) experienced adverse events that were possibly study-drug related: pyrexia and intraocular inflammation that resolved with a topical steroid. Five of ten patients who received 2 × 10¹⁰ vg had aqueous humour concentrations of sFLT01 that peaked at 32·7-112·0 ng/mL (mean 73·7 ng/mL, SD 30·5) by week 26 with a slight decrease to a mean of 53·2 ng/mL at week 52 (SD 17·1). At baseline, four of these five patients were negative for anti-AAV2 serum antibodies and the fifth had a very low titre (1:100) of anti-AAV2 antibodies, whereas four of the five non-expressers of sFLT01 had titres of 1:400 or greater. In 11 of 19 patients with intraretinal or subretinal fluid at baseline judged to be reversible, six showed substantial fluid reduction and improvement in vision, whereas five showed no fluid reduction. One patient in cohort 5 showed a large decrease in vision between weeks 26 and 52 that was not thought to be vector-related.

INTERPRETATION

Intravitreous injection of AAV2-sFLT01 seemed to be safe and well tolerated at all doses. Additional studies are needed to identify sources of variability in expression and anti-permeability activity, including the potential effect of baseline anti-AAV2 serum antibodies.

FUNDING

Sanofi Genzyme, Framingham, MA, USA.

Discovery of pan-VEGF inhibitory peptides directed to the extracellular ligand-binding domains of the VEGF receptors

Receptor tyrosine kinases (RTKs) are key molecules in numerous cellular processes, the inhibitors of which play an important role in the clinic. Among them are the vascular endothelial growth factor (VEGF) family members and their receptors (VEGFR), which are essential in the formation of new blood vessels by angiogenesis. Anti-VEGF therapy has already shown promising results in oncology and ophthalmology, but one of the challenges in the field is the design of specific small-molecule inhibitors for these receptors. We show the identification and characterization of small 6-mer peptides that target the extracellular ligand-binding domain of all three VEGF receptors. These peptides specifically prevent the binding of VEGF family members to all three receptors and downstream signaling but do not affect other angiogenic RTKs and their ligands. One of the selected peptides was also very effective at preventing pathological angiogenesis in a mouse model of retinopathy, normalizing the vasculature to levels similar to those of a normal developing retina. Collectively, our results suggest that these peptides are pan-VEGF inhibitors directed at a common binding pocket shared by all three VEGFRs. These peptides and the druggable binding site they target might be important for the development of novel and selective small-molecule, extracellular ligand-binding inhibitors of RTKs (eTKIs) for angiogenic-dependent diseases.

Radiation-enhanced Endostatin Gene Expression and Effects of Combination Treatment

Targeting cells that support tumor growth by administering potent angiogenesis inhibitors is currently an area of intense interest. In the present study, a unique plasmid vector for the mouse endostatin gene, pXLG-mEndo, was constructed and evaluated with and without radiation using the Lewis lung carcinoma (LLC) cell line. The physical properties of the expressed endostatin protein were validated by PCR, gel electrophoresis, and Western blot. Enzyme-linked immunosorbent and immunocytochemical analyses for the therapeutic gene demonstrated that transfected LLC cells secreted the protein into the medium. Exposure of the cells to 2 gray (Gy) γ-rays reduced the time to reach the maximum expression level of the endostatin gene and also increased the amount of secreted endostatin protein (P<0.001). Biological activity of the endostatin was demonstrated by the inhibition of tube formation by human umbilical vein endothelial cells (HUVEC). Based on 3 H-thymidine incorporation, endostatin expression significantly depressed DNA synthesis in HUVEC and LLC cells compared to controls transfected with parental vector or no vector (P>0.005). In addition, radiation increased the efficiency of endostatin-mediated inhibition of both cell types over a 3-day period post-exposure (P<0.05 or less). Intratumoral injection of 100 μg pXLG-mEndo combined with 10 Gy radiation significantly delayed LLC tumor growth, especially when each modality was delivered twice (P<0.05 or less compared to all other groups). No toxicity was observed. These findings are very promising and suggest that endostatin therapy with a plasmid vector, such as pXLG-mEndo, may enhance the efficacy of radiotherapy for lung cancer.

Full-Length Semaphorin-3C Is an Inhibitor of Tumor Lymphangiogenesis and Metastasis

Semaphorins play important regulatory roles in diverse processes such as axon guidance, angiogenesis, and immune responses. We find that semaphorin-3C (sema3C) induces the collapse of the cytoskeleton of lymphatic endothelial cells (LEC) in a neuropilin-2-, plexin-D1-, and plexin-A1-dependent manner, while most other semaphorins, including antiangiogenic semaphorins such as sema3A do not. Sema3C is cleaved, like other class-3 semaphorins, by furin-like pro-protein convertases (FPPC). Cleaved sema3C (p65-Sema3C) was unable to induce the collapse of the cytoskeleton of LEC. FPPC are strongly upregulated in tumor cells. In order to examine the effects of full-length sema3C on tumor progression, we therefore generated an active point mutated furin cleavage-resistant sema3C (FR-sema3C). FR-sema3C inhibited potently proliferation of LEC and to a lesser extent proliferation of human umbilical vein-derived endothelial cells. FR-sema3C also inhibited VEGF-C-induced phosphorylation of VEGFR-3, ERK1/2, and AKT. Expression of recombinant FR-sema3C in metastatic, triple-negative LM2-4 breast cancer cells did not affect their migration or proliferation in vitro. However, tumors derived from FR-sema3C-expressing LM2-4 cells implanted in mammary fat pads developed at a slower rate, contained a lower concentration of blood vessels and lymph vessels, and metastasized much less effectively to lymph nodes. Interestingly, p65-Sema3C, but not FR-sema3C, rendered A549 lung cancer cells resistant to serum deprivation, suggesting that previously reported protumorigenic activities of sema3C may be due to p65-Sema3C produced by tumor cells. Our observations suggest that FR-sema3C may be further developed into a novel antitumorigenic drug.

Antiangiogenic Metargidin Peptide (AMEP) Gene Therapy in Disseminated Melanoma

Gene delivery by electroporation is an efficient method for transfecting genes into various tissues including tumors. Here we present the treatment protocol used in a phase 1 study on gene electrotransfer of plasmid DNA encoding an antiangiogenic peptide into cutaneous melanoma.

EZH2 promotes angiogenesis through inhibition of miR-1/Endothelin-1 axis in nasopharyngeal carcinoma

Emerging evidence clearly indicates that EZH2 plays a crucial role in tumor angiogenesis. However, the role of EZH2 in angiogenesis is still unknown in nasopharyngeal carcinoma (NPC). We here showed that the elevated EZH2 level was closely associated with an aggressive and poor prognostic phenotype, and was positively correlated with microvessel density (MVD) in NPC tissues. Functional studies showed that EZH2 upregulation promoted cell proliferation, migration and tubule formation of endothelial cells, and knockdown of EZH2 suppressed tumor growth, metastasis and angiogenesis in vivo. Mechanistic investigations revealed that EZH2 inhibited miR-1 transcription via promoter binding activity, leading to enhanced expression of Endothelin-1 (ET-1) which is suppressed by miR-1 targeting of ET-1 3'UTR. Furthermore, knockdown of EZH2 or overexpression of miR-1 exerted anti-angiogenic effect on NPC cells. More importantly, the neutralizing antibody against ET-1 significantly abrogated the pro-angiogenic effect of EZH2, and forced expression of ET-1 rescued the anti-angiogenic effect induced by EZH2 knockdown. In clinical specimens, ET-1 was widely overexpressed and associated with clinical stage and MVD. Taken together, our results identify a novel signaling pathway involved in NPC angiogenesis, and also suggest that EZH2-miR-1-ET-1 axis represents multiple potential therapeutic targets for NPC.

Antiangiogenic activity of hypoxylonol C

Hypoxylonol C (1), isolated from the inedible mushroom Hypoxylon truncatum, exhibited inhibitory activities against the migration and tube formation of HUVECs. A cDNA microarray analysis was performed to investigate the target of hypoxylonol C (1) in HUVECs, and it was found that the genes related to cell cycle and adhesion were down-regulated. The down-regulation of mRNA levels of cell cycle and adhesion genes was confirmed by real-time RT-PCR. Cell cycle arrest and suppression of adhesion molecule expression might be plausible mechanisms of actions for the antiangiogenic activity of hypoxylonol C (1).

GroEL1, a heat shock protein 60 of Chlamydia pneumoniae, impairs neovascularization by decreasing endothelial progenitor cell function

The number and function of endothelial progenitor cells (EPCs) are sensitive to hyperglycemia, hypertension, and smoking in humans, which are also associated with the development of atherosclerosis. GroEL1 from Chlamydia pneumoniae has been found in atherosclerotic lesions and is related to atherosclerotic pathogenesis. However, the actual effects of GroEL1 on EPC function are unclear. In this study, we investigate the EPC function in GroEL1-administered hind limb-ischemic C57BL/B6 and C57BL/10ScNJ (a toll-like receptor 4 (TLR4) mutation) mice and human EPCs. In mice, laser Doppler imaging, flow cytometry, and immunohistochemistry were used to evaluate the degree of neo-vasculogenesis, circulating level of EPCs, and expression of CD34, vWF, and endothelial nitric oxide synthase (eNOS) in vessels. Blood flow in the ischemic limb was significantly impaired in C57BL/B6 but not C57BL/10ScNJ mice treated with GroEL1. Circulating EPCs were also decreased after GroEL1 administration in C57BL/B6 mice. Additionally, GroEL1 inhibited the expression of CD34 and eNOS in C57BL/B6 ischemic muscle. In vitro, GroEL1 impaired the capacity of differentiation, mobilization, tube formation, and migration of EPCs. GroEL1 increased senescence, which was mediated by caspases, p38 MAPK, and ERK1/2 signaling in EPCs. Furthermore, GroEL1 decreased integrin and E-selectin expression and induced inflammatory responses in EPCs. In conclusion, these findings suggest that TLR4 and impaired NO-related mechanisms could contribute to the reduced number and functional activity of EPCs in the presence of GroEL1 from C. pneumoniae.

In vivo monitoring of angiogenesis inhibition via down-regulation of mir-21 in a VEGFR2-luc murine breast cancer model using bioluminescent imaging

MicroRNA-21 (miR-21) is overexpressed in a wide range of cancers and involved in tumor proliferation and metastasis. However, the potential function of miR-21 in regulating tumor angiogenesis has been little disclosed. In this study, we treated the cultured 4T1 murine breast cancer cells and human umbilical vein endothelial cells (HUVECs) with miR-21 mimic, antagomir-21 or negative control (scramble), which were subjected to MTT, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), quantitative Reverse Transcriptase PCR (qRT-PCR) and immunoblotting analysis. In addition, 4T1 cells were implanted beneath the right breast fat pad of the VEGFR2-luc transgenic mice, which were randomly divided into three groups and received saline, antagomir-21 or scramble treatment once respectively after tumor model establishment. Bioluminescent imaging was used to monitor tumor growth and angiogenesis in vivo at 0d, 3d, 5d, 7d, 10d, and 14d after treatment. Mice were killed at the end of study and tumor tissues were collected for use. The results showed that knockdown of miR-21 by antagomir-21 decreased cell proliferation and induced apoptosis via targeting PTEN both in 4T1 cells and HUVECs. We also found the anti-angiogenesis and anti-tumor effects of antagomir-21 in the VEGFR2-luc transgenic mouse model using bioluminescent imaging. Moreover, the Western blotting data revealed that antagomir-21 inhibited tumor angiogenesis through suppressing HIF-1α/VEGF/VEGFR2-associated signaling pathway. In conclusion, the results from current study demonstrate that antagomir-21 can effectively suppress tumor growth and angiogenesis in VEGFR2-luc mouse breast tumor model and bioluminescent imaging can be used as a tool for noninvasively and continuously monitoring tumor angiogenesis in vivo.

The effect of intracellular protein delivery on the anti-tumor activity of recombinant human endostatin

Endostatin (ES), a 20 kDa protein derived from the carboxy-terminus of collagen XVIII is a potent angiogenesis inhibitor, but clinical development has been hindered by poor clinical efficacy and insufficient functional information from which to design agents with improved activity. The present study investigated protein uptake by cells as a determinant of ES activity. We developed a cell-permeable ES protein (HM73ES) with enhanced capacity to enter cells by adding a macromolecule transduction domain (MTD). HM73ES inhibited angiogenesis-associated phenotypes in cultured endothelial cells [as assessed by tube formation, wound-healing, cell proliferation and survival assays]. These effects were accompanied by reductions in MAPK signaling (ERK phosphorylation), and in β-Catenin, c-Myc, STAT3, and VEGF protein expression. The cell-permeable ES displayed greater tissue penetration in mice and suppressed the growth of human tumor xenografts to a significantly greater extent than ES protein without the MTD sequence. Our results suggest that anti-angiogenic activities of native ES are limited at the level of protein uptake and/or subcellular localization, and that much of the activity of ES against tumors depends on one or more intracellular functions. This study will inform future efforts to understand ES function(s) and suggest strategies for improving ES-based cancer therapeutics.

Antiangiogenic therapies for advanced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a significant cause of death worldwide. HCC is a highly vascular tumor, and proangiogenic cytokines such as vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and fibroblast growth factor may play crucial roles in this disease. Sorafenib, a multikinase inhibitor that blocks VEGF and PDGF signaling, was the first systemic therapy to demonstrate improved survival in patients with advanced HCC. Several other drugs targeting VEGF are in development. Because of the anticipation of eventual resistance to anti-VEGF therapies, drugs that also target alternative proangiogenic pathways are being investigated. Recent clinical and preclinical data along with ongoing studies are reviewed.

[Current situation and prospect of tenomodulin in tendon tissue engineering]

OBJECTIVE

To review the latest researches of Tenomodulin in tendon tissue engineering, to predict the progress of research and application of Tenomodulin.

METHODS

The literature concerning Tenomodulin in tendon tissue engineering was collected and analyzed.

RESULTS

Tenomodulin is a type II transmembrane glycoprotein that can regulate growth of tendon and contains a C-terminal anti-angiogenic domain. The human Tenomodulin gene spans approximately 1360 bp and is mapped to Xq22.1. The expression of Tenomodulin is regulated by various biological factors, especially Scleraxis; and the nature and structure of scaffold material as well as the stain loading and cell passage, can modulate the expression of Tenomodulin.

CONCLUSION

Tenomodulin, as relatively specific molecule makers for tendon and containing a C-terminal anti-angiogenic domain, is expected to play a significant role in tendon tissue engineering.

[Recombinant fragment of pigment epithelium-derived factor (44-77) prevents pathological corneal neovascularization]

Pigment epithelium-derived factor (PEDF), a 50 kDa secreted glycoprotein, is among the most potent endogenous inhibitors of angiogenesis. PEDF-derived fragment (44-77) possesses antiangiogenic properties of the full-sized protein and is a potential drug candidate for the treatment of ocular neovascular diseases. In this study we propose an efficient scalable biotechnological method for the production of PEDF (44-77) as part of a fusion protein with SspDnaB intein. The fusion protein was obtained in bacterial E. coli cells in the form of inclusion bodies, solubilized and subjected to autocatalytic cleavage with the release of PEDF (44-77) (yield, 77%). The target peptide was separated from the intein using tangential ultrafiltration. The final purification of PEDF (44-77) was performed by reversed-phase HPLC. The yield of the target peptide (purity, 99%) was 65 mg per 1 liter of culture. Antiangiogenic activity of the obtained peptide was studied in vitro using murine endothelial cells SVEC-4-10. PEDF (44-77) suppressed proliferation of endothelial cells by 53% and inhibited endothelial cell tube formation at the concentration of 1 nM. The ability of the recombinant PEDF (44-77) to block initial stages of angiogenesis was demonstrated using the model of rabbit corneal neovascularization.

TIMP-2 fusion protein with human serum albumin potentiates anti-angiogenesis-mediated inhibition of tumor growth by suppressing MMP-2 expression

TIMP-2 protein has been intensively studied as a promising anticancer candidate agent, but the in vivo mechanism underlying its anticancer effect has not been clearly elucidated by previous works. In this study, we investigated the mechanism underlying the anti-tumor effects of a TIMP-2 fusion protein conjugated with human serum albumin (HSA/TIMP-2). Systemic administration of HSA/TIMP-2 effectively inhibited tumor growth at a minimum effective dose of 60 mg/kg. The suppressive effect of HSA/TIMP-2 was accompanied by a marked reduction of in vivo vascularization. The anti-angiogenic activity of HSA/TIMP-2 was directly confirmed by CAM assays. In HSA/TIMP-2-treated tumor tissues, MMP-2 expression was profoundly decreased without a change in MT1-MMP expression of PECAM-1-positive cells. MMP-2 mRNA was also decreased by HSA/TIMP-2 treatment of human umbilical vein endothelial cells. Zymographic analysis showed that HSA/TIMP-2 substantially decreased extracellular pro-MMP-2 activity (94–99% reduction) and moderately decreased active MMP-2 activity (10–24% reduction), suggesting MT1-MMP-independent MMP-2 modulation. Furthermore, HSA/TIMP-2 had no effect on in vitro active MMP-2 activity and in vivo MMP-2 activity. These studies show that HSA/TIMP-2 potentiates anti-angiogenic activity by modulating MMP-2 expression, but not MMP-2 activity, to subsequently suppress tumor growth, suggesting an important role for MMP-2 expression rather than MMP-2 activity in anti-angiogenesis.

[Oncolytic poxviruses]

The latest data on selection and construction of poxviruses capable of specifically lysing tumor cells of different genesis, inducing antitumor immunity and apoptosis of malignant cells are discussed. The review concerns several directions: virus attenuation, insertion of immunomodulatory protein genes, and anti-tumor protein genes. Thymidine kinase and viral growth factor genes make the greatest contribution to the virus attenuation as their inactivation results in the virus inability to replicate in non-dividing cells, thereby contributing to increased selectivity with respect to tumor cells. Among the immunomodulatory proteins, interleukins 2, 12, and granulocyte-macrophage colony-stimulating factor proved to be most promising for oncolytic virotherapy. An attempt to use p53 protein gene expressed by vaccinia virus for addressed apoptosis of tumor cells was reported. The use of the double and triple viral recombinants carrying genes of multidirectional action seems to be most promising. Encouraging results were obtained using vaccinia virus in the oncotherapy with prodrugs and angiogenesis inhibitors. At present, two poxviral strains are undergoing Phase III clinical trials as anti-tumor preparations in the USA.

Leucurogin, a new recombinant disintegrin cloned from Bothrops leucurus (white-tailed-jararaca) with potent activity upon platelet aggregation and tumor growth

Disintegrins and disintegrins-like proteins are able to inhibit platelet aggregation and integrin-mediated cell adhesion. The aim of this study was to produce one disintegrin-like cloned from Bothrops leucurus venom gland and to characterize it regarding biological activity. The recombinant protein was purified by one step procedure involving anion-exchange chromatography (DEAE-cellulose) and presented a molecular mass of 10.4 kDa. The purified protein was able to inhibit platelet aggregation induced by collagen (IC₅₀ = 0.65 μM) and to inhibit growth of Ehrlich tumor implanted in mice by more than 50% after 7 days administration of 10 μg/day. No effects were observed upon adenosine 5'-diphosphate (ADP)-and arachidonic acid (AA)-induced platelet aggregation. The recombinant protein was recognized by an antibody specific for jararhagin one metalloproteinase isolated from Bothrops jararaca venom, and therefore it was named leucurogin. Anti-angiogenesis effect of leucurogin was evaluated by the sponge implant model. After 7 days administration leucurogin inhibited, in a dose dependent way, the vascularization process in the sponge. Leucurogin represents a new biotechnological tool to understand biological processes where disintegrins-like are involved and may help to characterize integrins that can be involved in development and progression of malignant cells.

Regulation of vascular endothelial growth factor signaling by miR-200b

Vascular endothelial growth factor (VEGF) signaling plays an important role in angiogenesis. In the VEGF signaling pathway, the key components are VEGF and its receptors, Flt-1 and KDR. In this study, we show that transfection of synthetic miR-200b reduced protein levels of VEGF, Flt-1, and KDR. In A549 cells, miR-200b targeted the predicted binding sites in the 3'-untranslated region (3'-UTR) of VEGF, Flt-1, and KDR as revealed by a luciferase reporter assay. When transfected with miR-200b, the ability of HUVECs to form a capillary tube on Matrigel and VEGF-induced phosphorylation of ERK1/2 were significantly reduced. Taken together, these results suggest that miR-200b negatively regulates VEGF signaling by targeting VEGF and its receptors and that miR-200b may have therapeutic potential as an angiogenesis inhibitor.

Targeting angiogenesis for cancer (gene) therapy

Suppression of development of new blood vessels in solid tumors provides a clear therapeutic benefit both in experimental animals and human patients. Molecules targeting multiple pathways with VEGF pathway being one of the best described are currently under consideration to reach use in clinical settings. Even though some success has been observed using traditional protein-based inhibitors, alternative strategies and new approaches to inhibit excessive tumor angiogenesis are being developed and tested. Gene therapy represents a powerful tool for therapeutic intervention to angiogenesis. Delivery of genes encoding endogenous angiogenesis inhibitors and decoy receptors for proangiogenic factors may bear an advantage over classic non-gene therapy in terms of specific targeting, cost-effectiveness and safety. Modern approaches focused on gene targeting such as RNA interference and microRNA will show the future direction in the field of angiogenesis inhibition for cancer treatment (Ref. 68).

A functional role of the glycosylated N-terminal domain of chondromodulin-I

Chondromodulin-I (ChM-I) is a 25-kDa glycoprotein that specifically localizes in the extracellular matrix of cartilage and negatively regulates angiogenesis. ChM-I comprises two domains: an N-terminal hydrophilic domain (domain 1) containing an N-linked glycosylation site and a C-terminal hydrophobic domain (domain 2) with all four disulfide bonds that are present in this protein. We generated a nonglycosylated recombinant human ChM-I (NG-hChM-I) and compared its bioactivity with that of the glycosylated form of human ChM-I (G-hChM-I) expressed in Chinese hamster ovary cells in vitro. NG-hChM-I exhibited the growth factor/inhibitor activity in the cultures of chondrocytes and vascular endothelial cells but required markedly higher doses. Although domain 1 is predicted to be hydrophilic per se on the basis of its amino acid sequence, NG-hChM-I remains insoluble in aqueous solution as much as ΔN-hChM-I that lacks the N-terminal 37 amino acids containing an N-glycosylation site. Circular dichroism measurements revealed that the content of α-helix was calculated to be 34% in G-hChM-I, whereas the content of the characteristic secondary structures in NG-hChM-I was distinctly lower than those in G-hChM-I. These results indicate that glycosylation in domain 1 is critical for the structural integrity for biological functions of ChM-I in vitro.

[Endothelial genesis inhibitor-8t (EDI-8t) against tumor growth]

On the basis of the origin comparison of known endothelial genesis inhibitors, a 417-bp cDNA fragment was amplified from umbilical cord by RT-PCR and cloned into the expression vector pPIC9, followed by transformation into Pichia pastoris GS115. The resulted yeast was induced with methanol to express recombinant protein. The resulted protein was purified from culture broth and designated as EDI-8t. The in vitro study showed that EDI-8t, originated from collagen VIII, could specifically inhibit the growth and migration of bovine aortic endothelial cells (BAEC) stimulated by basic fibroblast growth factor (bFGF). The protein also exhibited the activity to cause cell apoptosis. In vivo EDI-8t showed the identical activity comparing with endostatin to inhibit the growth of liver tumor transplanted into nude mice. Interestingly, EDI-8t showed higher activity than endostatin to inhibit tumor growth in metastatic model of melanoma mice.

Listeria and Salmonella bacterial vectors of tumor-associated antigens for cancer immunotherapy

This review covers the use of the facultative intracellular bacteria, Listeriamonocytogenes and Salmonella enterica serovar typhimurium as delivery systems for tumor-associated antigens in tumor immunotherapy. Because of their ability to infect and survive in antigen presenting cells, these bacteria have been harnessed to deliver tumor antigens to the immune system both as bacterially expressed proteins and encoded on eukaryotic plasmids. They do this in the context of strong innate immunity, which provides the required stimulus to the immune response to break tolerance against those tumor-associated antigens that bear homology to self. Here we describe differences in the properties of these bacteria as vaccine vectors, a summary of the major therapies they have been applied to and their advancement towards the clinic.

Retinal vascular leakage occurring in GABA Rho-1 subunit deficient mice

Recent studies demonstrate that GABAergic activity elicits relaxation of retinal arterioles leading to an increase in blood flow. It has also been found that GABAnergic activity in the retina of mice with diabetic retinopathy is suppressed. In this study, we provide further evidence that lack of GABAergic activity significantly alters vasculature development as well as the hypoxia-induced angiogenic response. Using GABA(C) receptor rho(1) subunit-knockout mice (rho-1(-/-)), our results demonstrate that in hypoxia-induced retinas a severe vascular leakage occurred in 2 week-old rho-1(-/-) mice compared with their wildtype counterparts. In addition, our results also showed that all of the rho-1(-/-) mice developed significant retinal vascular leakages by 48 weeks-of-age. Microarray and real-time PCR experiments revealed a unique angiogenesis-related gene expression pattern. This suggests that retinal vascular disorders of rho-1(-/-) mice results from significant up-regulation of angiogenic genes and concomitant down-regulation of anti-angiogenic genes. The study results are consistent with the pathological changes of the retinal vascular leakage seen in diabetic retinopathy. Our data indicate that the GABA(C) rho(1) subunit plays a role in maintaining both homeostasis and balance of retinal neurotransmitter function. Knockout of the retinal GABA(C) rho(1)-subunit leads to changes in vascular permeability similar to the pathological changes induced by retinal hypoxic conditions.

[Human endostatin antiangiogenic gene therapy mediated by recombinant adeno-associated virus vector in nude mouse with endometriosis]

OBJECTIVE

To study the therapeutic effect of recombinant adeno-associated virus carrying human endostatin gene therapy on endometriosis in mice model.

METHODS

Recombinant adeno-associated virus vector carrying human endostatin gene and enhanced green fluorescent proteins gene (rAAV2-endostatin-EGFP) was constructed. Endometrium was from 12 patients with leiomyoma undergoing hysterectomy in Second Hospital, Tianjin Medical University between November and December 2008. Endometriosis models of nude mice were established by transplanting human endometrial fragments intooperitoneal surface. After 1 week, those 60 mice were divided into 3 groups: treatment group including 20 mice injected with rAAV2-endostatin-EGFP to ectopic lesion, control group including 20 mice injected with rAAV2-EGFP to ectopic lesion and blank control group including 20 mice injected with phosphate buffered saline (PBS) to the ectopic lesion. At 1, 2 and 3 weeks after treatment, those mice underwent laparotomy to observe the location and size of ectopic lesion in abdominal cavity. The expression of endostain protein, number of gland, microvessel density (MVD) and vascular endothelial growth factor (VEGF) were measured in ectopic lesions. The serum level of estradiol and progesterone were detected in nude mice among every groups.

RESULTS

(1) All endometriosis of nude mice models were established successfully through peritoneum transplanting. After 1 week's treatment, flat lesion nodes, decreased gland number and narrow and atrophy glandular cavity were observed by light microscope. (2) The endostatin gene was transferred into nude mice successfully and expressed effectively. It was observed that endostatin protein expression was shown with enhanced green fluorescent proteins in ectopic lesion. (3) Glands number of ectopic lesion in rAAV2-endostatin-EGFP group (7.8 ± 1.9, 7.0 ± 1.5 and 5.5 ± 1.7) were significantly less than 10.1 ± 1.7, 10.2 ± 2.0 and 9.8 ± 2.4 in rAAV2-EGFP control group and 10.2 ± 2.2, 10.0 ± 2.0 and 9.7 ± 2.2 in PBS control group at 1, 2 and 3 weeks after treatment (all P < 0.05). Glands number of ectopic lesion in rAAV2-endostatin-EGFP group at 3 weeks was significantly less than those at 1 and 2 weeks after treatment (P < 0.05). (4) MVD of ectopic lesion in rAAV2-endostatin-EGFP group (12.2 ± 1.5, 11.4 ± 2.1 and 9.0 ± 1.4) was significantly less than those at rAAV2-EGFP control group (16.5 ± 1.7, 16.5 ± 1.9 and 16.9 ± 1.9) and PBS control group (16.2 ± 1.6, 16.0 ± 1.6 and 16.3 ± 1.7) at 1, 2 and 3 weeks after treatment (all P < 0.05). MVD of ectopic lesion in rAAV2-endostatin-EGFP group at 3 weeks was significantly less than those at 1 and 2 weeks after treatment (P < 0.05). (5) The rate and density of VEGF expression at ectopic lesion in rAAV2-endostatin-EGFP group (35%, 30%, 25% and 1.60 ± 0.43, 1.33 ± 0.30, 1.03 ± 0.36) were significantly less than those at rAAV2-EGFP control group (80%, 75%, 85% and 2.43 ± 0.53, 2.43 ± 0.29, 2.66 ± 0.45) and PBS control group (85%, 90%, 90% and 2.36 ± 0.53, 2.64 ± 0.57, 2.53 ± 0.52) at one 1, 2 and 3 weeks after treatment (all P < 0.05). The expression of VEGF at ectopic lesion in rAAV2-endostatin-EGFP group at 3 weeks was significantly less than those at 1 and 2 weeks after treatment (P < 0.05). (6) The level of estradial and progesterone in serum of nude mice of rAAV2-endostatin-EGFP group [E(2): (48 ± 7) pmol/L, P: (61 ± 8) nmol/L] did not reach statistical difference when compared with those at rAAV2-EGFP control group [E(2): (50 ± 9) pmol/L, P: (60 ± 10) nmol/L] and PBS control group [E(2): (48 ± 7) pmol/L, P: (58 ± 10) nmol/L, P > 0.05].

CONCLUSIONS

The recombinant adeno-associated virus carrying human endostatin gene therapy could inhibit angiogenesis at endometriotic lesions and not influence steroid level. The antiangiogenic gene therapy might become a novel option for endometriosis.

An anti-vascular endothelial growth factor receptor 2/fetal liver kinase-1 Listeria monocytogenes anti-angiogenesis cancer vaccine for the treatment of primary and metastatic Her-2/neu+ breast tumors in a mouse model

Thirty years after angiogenesis was shown to play an enabling role in cancer, modern medicine is still trying to develop novel compounds and therapeutics to target the tumor vasculature. However, most therapeutics require multiple rounds of administration and can have toxic side effects. In this study, we use anti-angiogenesis immunotherapy to target cells actively involved in forming new blood vessels that support the growth and spread of breast cancer. Targeting a central cell type involved in angiogenesis, endothelial cells, we immunized against host vascular endothelial growth factor receptor 2 to fight the growth of Her-2/neu(+) breast tumors. Using the bacterial vector, Listeria monocytogenes (Lm), we fused polypeptides from the mouse vascular endothelial growth factor receptor 2 molecule (fetal liver kinase-1) to the microbial adjuvant, listeriolysin-O, and used Lm to deliver the Ags and elicit potent antitumor CTL responses. Lm-listeriolysin-O-fetal liver kinase-1 was able to eradicate some established breast tumors, reduce microvascular density in the remaining tumors, protect against tumor rechallenge and experimental metastases, and induce epitope spreading to various regions of the tumor-associated Ag Her-2/neu. Tumor eradication was found to be dependent on epitope spreading to HER-2/neu and was not solely due to the reduction of tumor vasculature. However, vaccine efficacy did not affect normal wound healing nor have toxic side effects on pregnancy. We show that an anti-angiogenesis vaccine can overcome tolerance to the host vasculature driving epitope spreading to an endogenous tumor protein and drive active tumor regression.

[In vivo antitumor effect of canstatin gene on human esophageal carcinoma xenografts in nude mice]

BACKGROUND AND OBJECTIVE

Canstatin is a newly discovered endogenous inhibitor of angiogenesis. Previous study has shown that canstatin can efficiently suppress the growth of human cancers, even more potent than endostatin. This study was to investigate the antitumor effects of canstatin gene on human esophageal carcinoma xenografts.

METHODS

Tumor xenografts were induced with KYSE150 cells in BALB/c nude mice, and randomized into three groups: PBS, adenovirus green fluorescent protein (Ad-GFP), and Ad-GFP-canstatin groups. During treatment, tumor size was measured. The mice were killed 30 days later to observe tumor morphology. The expression of vascular endothelial growth factor (VEGF), fetal liver kinase-1 (Flk-1), caspase-3 and microvessel density (MVD) were detected by immunohistochemistry.

RESULTS

Compared with that in Ad-GFP and PBS groups, tumor growth in Ad-GFP-canstatin group was significantly suppressed in the first week after gene transfection. The inhibition rate of tumor growth was up to 61% at the sixth day. Necrotic regions were observed in all groups, especially in Ad-GFP-canstatin group. Compared with those in Ad-GFP and PBS groups, caspase-3 expression in Ad-GFP-canstatin group was higher (P<0.05), while Flk-1 expression and MVD was lower (P<0.05). There was no obvious difference in VEGF expression among the three groups.

CONCLUSION

Canstatin can inhibit the growth of human esophageal carcinoma by suppressing angiogenesis via down-regulating Flk-1 expression.

[Anti-angiogenesis effect of G4PAMAM/VEGFASODN on breast cancer in vitro]

OBJECTIVE

To investigate the effect of G4PAMAM/VEGFASODN compound on expression of VEGF and VEGF mRNA in MDA-MB-231 breast cancer cells and the growth inhibition of vascular endothelial cells.

METHODS

The diameter of G4PAMAM/VEGFASODN granule was measured by transmission electron microscopy, and its stability under different pH was also observed. The efficiency of transfection in vitro was detected by flow cytometer and the positively transfected cells were detected by laser scanning confocal microscope. The survival rate and the inhibitory rate of vascular endothelial cells were determined by MTT assay. The expression of protein VEGF was detected by immunohistochemical method and the expression of VEGF mRNA was detected by RT-PCR.

RESULT

The diameter of G4PAMAM/VEGFASODN granules was about 10 nm and it arranged as homogeneous netlike. Under pH 5-10 G4PAMAM/VEGFASODN presented highly stable and no dissociation was observed with different charge ratios. The 48-hour transfection rate of G4PAMAM/VEGFASODN in charge ratio of 1:40 was significantly higher than that of the lipofectamine group. None of the transfection products in each group showed cell toxicity. The staining of VEGF protein in the cytoplasm of MDA-MB-231 cells after G4PAMAM/ASODN transfection weakened markedly, and the positive expression rate decreased. Meanwhile, the VEGF mRNA expression was also decreased.

CONCLUSION

With good stability and transfection rate, compound G4PAMAM/VEGFASODN can be a promising new nanometer vector of gene transfer system. The G4PAMAM/VEGFASODN can inhibit the expression of VEGF gene specifically and efficiently, which may be used for in vivo animal experiment.

[Construction and activity of recombinant adeno-associated virus expressing vasostatin]

Vasostatin, a 180-amino acid fragment from the N-terminal domain of calreticulin, is a potent endogenous angiogenesis inhibitor, which can inhibit the growth of many kinds of experimental tumor. But a recent report that vasostatin can enhance the malignant behavior of neuroendocrine tumor reminds us to be cautious to develop it as an anti-tumor medicine. VAS cDNA was cloned into pAAV-2 expression vector; recombinant virus rAAV-VAS was generated by a three plasmids, helper free packaging method. MS1 mouse pancreatic endothelial cell and human colon tumor HCT-116 cell were infected with rAAV-VAS. Transgene expression was analyzed by Western blotting analysis; cell proliferation was determined by MTT assay. The therapeutic potential of rAAV-VAS was evaluated in subcutaneous HCT-116 xenograft mouse model. rAAV-VAS inhibited the proliferation of MS1 but not HCT-116 cell. HCT-116 cell infected with rAAV-VAS secreted VAS protein into the supernatant effectively. The intratumoral delivery of rAAV-VAS inhibited the xenograft growth and microvessel density in tumors significantly. Our results show the effectiveness of rAAV-VAS as an angiogenesis inhibitor in suppressing tumor growth, validating the application of rAAV-VAS gene therapy in treatment against colon cancer.

[Inhibitory effects of transfection of arresten gene on liver metastasis from colorectal cancer in nude mice]

BACKGROUND & OBJECTIVE

Liver metastasis is the most common cause of death due to colorectal cancer. Above 50% colorecal cancer patients have liver metastasis. This study was to investigate the effect of transfection of arresten gene on liver metastasis from human colorectal cancer (LoVo) xenografts in nude mice.

METHODS

The eukaryotic expression plasmid pSecTag2-arresten was transfected into human colorectal cancer cell line LoVo using Lipofectamine 2000. Cells were divided into pSecTag2-arresten group, pSecTag2 group and control group. Expressions of arresten at mRNA and protein levels were detected by RT-PCR and Western blot, respectively. The effect of arresten on proliferation of LoVo cells was measured using MTT assay. LoVo cells transfected with pSecTag2-arresten were implanted into nude mice to investigate the effect of arresten on hepatic metastasis of colorectal cancer. Microvessel density (MVD) of xenograft tumors was assessed using immunohistochemistry with FVIIIRag monoclonal antibody.

RESULTS

Arresten was successfully transfected and expressed in LoVo cells. Inhibition of cell proliferation did not differ significantly in all three groups (P > 0.05). The metastastic rate was lower in pSecTag2-arresten group [(25.1+/-2.1)%] than in pSecTag2 group [(87.1+/-1.2)% or control group [(87.1+/-1.5)%] in LoVo cells (P < 0.05). The number of xenograft tumors and MVD were higher in pSecTag2-arresten group [(4.5 +/-0.5) and (15.3+/-3.5)] than in pSecTag2 group [(19.6+/-2.5) and (42.2+/-2.6)] or in control group [(20.4+/-2.5)and (45.6+/-5.1)] in nude mice.

CONCLUSION

Arresten can inhibit hepatic metastasis from colorectal cancer, which may be through its inhibition on tumor angiogenesis.

[Inhibition of corneal neovascularization by vascular endothelial growth inhibitor gene]

OBJECTIVE

To evaluate the effect of Effectene lipofectene mediated plasmids encoding human pcDNA4-vascular endothelia growth inhibitor (pcDNA4-VEGI) gene on corneal neovascularization (CNV).

METHODS

It was an experimental study. Forty healthy New Zealand albino rabbits (40 eyes) were divided into 4 teams according to the random digits table: team A (10 rabbits) was the team which transfected by lipofectine mediated plasmids encoding human pcDNA4-vascular endothelia growth inhibitor (pcDNA4-VEGI) gene; team B (10 rabbits) was the team transfected by empty vector; team C (10 rabbits) was the team transfected by lipofectine; team D (10 rabbits) was the empty control group which was transfected by saline. (1) Human VEGI gene fragment was connected with expressional vector plasmid pcDNA4 to construct the pcDNA4-VEGI gene expression vector. Computer automatic sequence analysis was used to identify the gene. (2) New Zealand albino rabbits were sutured by 5 - 0 silk in the superior cornea to establish the animal model and were transfected by pcDNA4-VEGI gene mediated by Effectene lipofectene transfection. Length and area of CNV were measured by slit lamp every day after transfection, immunohistochemistry was used to detected the expression of VEGI protein in cornea at the time 3, 7, 14 and 21 d.

RESULTS

(1) Computer automatic sequence analysis confirmed the correct recombination of pcDNA4-VEGI gene. (2) Average occurrence of CNV in the pcDNA4-VEGI gene transfected team was 6.3 days while that in the control teams were 3.1, 3.2, 3.2 days (F = 39.838, P < 0.01). Average length and area of CNV were also different in the VEGI team and the control teams (q between team A and B on average length of CNV was 17.386, 20.944 and 8.892 on 7, 14 and 21 d; q between team A and C on average length of CNV was 19.488, 19.795 and 7.483 on 7, 14 and 21 d; q between team A and C on average length of CNV was 19.583, 20.413 and 8.941 on 7, 14 and 21 d, and P were all < 0.01. And q between team A and B on average area of CNV was 30.238, 57.820 and 35.543 on 7, 14 and 21 d; q between team A and C on average area of CNV was 32.607, 57.843 and 36.653 on 7, 14 and 21 d; q between team A and C on average area of CNV was 33.873, 57.590 and 34.724 on 7, 14 and 21 d, and P were all < 0.01). Integrated epithelium, light stroma edema, less CNV and less inflammation could be seen in the gene-therapy team. And immunohistochemistry results showed VEGI positive cells in epithelium, stroma, endothelium and the cliff of CNV in the gene therapy team.

CONCLUSIONS

PCR, enzyme cutting, recombination and other genetic techniques could be used to construct expressional pcDNA4-VEGI gene. Effectene lipofectene transfection technique could be effectively used in transfecting pcDNA4-VEGI gene into rabbit cornea to inhibit CNV.

An Improved Strategy for High-Level Production of Human Vasostatin120-180

We previously reported a strategy for expression and purification of human Vasostatin120-180 (VAS), a potent angiogenesis inhibitor in a GST fusion form; however, the yield of 7.2 mg per liter of culture was relatively low. The aim of this study was to develop a more efficient system to improve and facilitate the production of VAS protein in a soluble and native form in Escherichia coli. The VAS gene with optimized condons was cloned into pET28a and overexpressed as a N-terminal His-tagged fusion protein. Between His-tag and VAS, an enterokinase recognition site was introduced to release the intact VAS. Optimal expression of soluble His-VAS was achieved by examining the contribution of chaperone coexpression and lower temperature fermentation. Ammonium sulfate precipitation was first employed to remove nucleic acid and partial host proteins. When further purified by Ni2+ affinity chromatography, 40 mg of His-VAS was isolated with purity over 85% from 1 L of culture. After desalting with Sephadex G15 and digestion with His-EK, followed by the removal of the His-tag and His-EK with Ni(2+)-NTA resin, 21 mg of intact VAS was finally obtained from 1 L of bacterial culture, which was approximately 3-fold the yield we previously obtained via GST fusion expression strategy. The identity of His-VAS and VAS was confirmed by Western blot. Purified VAS displayed distinct anti-angiogenic activity, which was shown by the endothelial cell proliferation inhibition assay and chicken chorioallantoic membrane assay. In sum, we greatly improved the yield of intact and bioactive VAS protein, and using this successful example, we propose a more efficient system for the high-level production of intact functional proteins, especially for low molecule weight peptides.

[Expression of biologically active recombinant arresten in Nicotiana tabacum]

In this report, the biological activity of the recombinant Arresten expressed in Nicotiana tabacum was studied. The gene coding for the tumor angiogenesis inhibitor Arresten was PCR-amplified from the plasmid pCA and its plant expression vector named pCAMBIAarr was constructed by inserting the Arresten cDNA fragment into the NcoI/BstEII sites of the plant binary expression vector pCAMBIA1301. Then pCAMBIAarr was transferred into Agrobacterium tumefacien LBA4404 by the freeze-thaw method. The adventitious shoots and regenerated plants of Nicotiana tabacum with hygromycinB-resistance were obtained via Agrobacterium-mediated leaf disk transformation method. Southern hybridization, RT-PCR and Western blotting analysis showed that the Arresten cDNA was integrated into the genome of some of the regenerated plants and the recombinant Arresten was expressed with a molecular size of 26 kD. Recombinant Arresten purified from transgenic tobacco leaves had an anti-proliferative effect on bovine endothelial cells. We speculate that biologically active recombinant Arresten can be produced by using plants as bioreactors.

Characterization of the anti-angiogenic properties of arresten, an alpha1beta1 integrin-dependent collagen-derived tumor suppressor

Physiological and pathological turnover of basement membranes liberates biologically active cryptic molecules. Several collagen-derived fragments possess anti-angiogenic activity. Arresten is the 26-kDa non-collagenous domain of type IV collagen alpha1 chain. It functions as an efficient inhibitor of angiogenesis and tumor growth in mouse models, but its anti-angiogenic mechanism is not completely known. Here we show that arresten significantly increases apoptosis of endothelial cells in vitro by decreasing the amount of anti-apoptotic molecules of the Bcl-family; Bcl-2 and Bcl-xL. Although the pro-apoptotic effect of arresten is endothelial cell specific in vitro, in mouse tumors arresten induced apoptosis both in endothelial and tumor cells. The tumor cell apoptosis is likely an indirect effect due to the inhibition of blood vessel growth into the tumor. The active site of arresten was localized by deletion mutagenesis within the C-terminal half of the molecule. We have previously shown that arresten binds to alpha1beta1 integrin on human umbilical vein endothelial cells. However, the microvascular endothelial cells (MLECs) are more important in the context of tumor vasculature. We show here that arresten binds also to the microvascular endothelial cells via alpha1beta1 integrin. Furthermore, it has no effect on Matrigel neovascularization or the viability of integrin alpha1 null MLECs. Tumors implanted on integrin alpha1 deficient mice show no integrin alpha1 expression in the host-derived vascular endothelium, and thus arresten does not inhibit the tumor growth. Collectively, this data sheds more light into the anti-angiogenic mechanism of arresten.

Expression of vasohibin, an antiangiogenic factor, in human choroidal neovascular membranes

PURPOSE

To determine whether vasohibin, an antiangiogenic factor produced by vascular endothelial cells, is expressed in the choroidal neovascular (CNV) membranes obtained from human eyes with age-related macular degeneration (AMD) or polypoidal choroidal vasculopathy (PCV).

DESIGN

Retrospective, interventional case series.

METHODS

The medical charts of 21 eyes of 21 patients with AMD or PCV who underwent surgical removal of the CNV membrane were reviewed. The removed tissues were immunostained for von Willebrand Factor (vWF), vascular endothelial growth factor (VEGF), and vasohibin. The levels of the messenger ribonucleic acid of VEGF, VEGFR2, and vasohibin were determined by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) from the CNV membranes excised from nine AMD and nine PCV patients.

RESULTS

The patients were divided into three groups; four patients were placed in the most active group (Group H), 13 in the less active group (Group E), and four in the nonactive group (Group S). Immunohistochemistry showed that vasohibin, vWF, and VEGF were expressed in the vascular endothelial cells in the CNV membranes and in the polypoidal vessels. RT-PCR showed that there was a strong correlation between the level of expression of VEGFR2 and vasohibin (P = .0002). Eyes with a lower vasohibin-to-VEGF ratio tended to have larger subretinal hemorrhages or vitreous hemorrhages, whereas eyes with higher vasohibin-to-VEGF ratio had subretinal fibrosislike lesions. Statistical analysis of the vasohibin-to-VEGF ratio among the three groups was significant (P = .0209).

CONCLUSIONS

Vasohibin is expressed in human CNV membranes. Our results indicate that the vasohibin-to-VEGF ratio may be related with the activity of the CNV.

Secreted human apolipoprotein(a) kringle IV-10 and kringle V inhibit angiogenesis and xenografted tumor growth

Abstract Angiogenesis plays an important role in normal physiology of blood vessel growth, but can contribute to the pathogenesis of diseases, such as cancer. A new anti-angiogenic recombinant kringle protein, composed of the fused domains of human apolipoprotein(a) carboxyl-terminal kringle IV-10 and kringle V, was expressed in Pichia pastoris and human colorectal carcinoma (HCT 116) cells to investigate its influence on angiogenesis and tumor growth. The mature recombinant protein exhibited the characteristic features of kringle-containing proteins (glycosylation and disulfide bond formation) and, when added to cultures of human umbilical vein endothelial cell, resulted in a 31% decrease in proliferation relative to untreated controls (p<0.05). The neo-angiogenesis was diminished by 63% in chick embryos treated with 10 mug recombinant protein compared with 7% for phosphate buffer solution-treated embryos (p<0.01). Transfection of a kringle IV-10-kringle V fusion protein construct into HCT 116 cells decreased tumorigenesis and inhibited tumor growth in vivo without affecting tumor cell proliferation. HCT 116 cells that expressed recombinant protein displayed a much lower relative growth ratio of 8% (p<0.01) against the control tumor cells. From these results, we conclude that human apolipoprotein(a) carboxyl-terminal kringle IV-10-kringle V fusion protein is an effective inhibitor of angiogenesis and angiogenesis-dependent tumor growth.

Basement membrane derived fibulin-1 and fibulin-5 function as angiogenesis inhibitors and suppress tumor growth

The fibulins are a family of secreted glycoproteins that are characterized by repeated epidermal-growth-factor-like domains and a unique C-terminus structure. Fibulins modulate cell morphology, growth, adhesion, and motility. Our initial basement membrane degradome screen using Cathepsin D, a tumor microenvironment-associated protease, contained fragments of fibulin-1 and full length fibulin-5. In this report, we evaluate the antiangiogenic activity of fibulin-1 and fibulin-5. Tumor studies demonstrate that both fibulin-1 and fibulin-5 suppress HT1080 tumor growth. CD31 labeling and TUNEL assay further reveal that fibulin-1 suppression of HT1080 tumor growth is associated with diminished angiogenesis and also enhanced apoptosis of endothelial cells and tumor cells. In contrast, fibulin-5 inhibits tumor angiogenesis with a minimal anti-apoptotic affect. Cathepsin D digestion of fibulin-1 produces a fragment with nearly the same molecular weight as fibulin-5, and this fragment (named Neostatin) inhibits endothelial cell proliferation. Additionally, degradation of basement membrane by cathepsin D liberates both fibulin-1 fragments and fibulin-5, which function to inhibit angiogenesis.

[Effect of METH1 gene transfection on the proliferation of rabbit's ear scar]

OBJECTIVE

To investigate the effect of METH1 gene transfection on fibroblast proliferation and I, III collagen synthesis in rabbit ear scar.

METHODS

The hypertrophic scar model on the rabbit ears was reproduced. 10 days after epithelization, Ad-METH1 was injected into the scar tissue. 30 days later, the effect of METH1 gene transfection on the angiogenesis, fibroblast proliferation and the ratio of collagen I/III in the scar tissue was detected by microcirculation microscope, AgNOR particle count and collagen dyeing.

RESULTS

30 days after injection of Ad-METH1, angiogenesis, fibroblast proliferation and the ratio of collagen I/III in the scar tissue were obviously suppressed.

CONCLUSION

Early application of Ad-METH1 after epithelization can markedly inhibit the formation of the hypertrophic scar.

[Inhibitory effect of adenovirus-mediated endostatin gene transfer on transplanted lung carcinoma in mice]

OBJECTIVE

To investigate the effect of adenovirus-mediated endostatin gene transfer on transplanted lung cancer in mice and its mechanism of action.

METHODS

Transplant tumor model was induced by subcutaneous inoculation of 2 x 10(6) Lewis lung cancer (LLC) cells into the back of C57BL/6 mice. The mice were treated by intratumoral injection of 2 x 10(9) pfu Ad-mEndostatin. The expression of endostatin in situ and its maintaining time were detected by immunohistochemistry and Western Blot, respectively. The endostatin level in serum was determined by ELISA . The inhibition of tumor growth and changes of survival were recorded and the microvessel density (MVD) was determined by histochemical stainingwith CD31 and CD105 antibodies. The tumor apoptosis was observed by electron microscopy.

RESULTS

In comparison with controls, intratumoral injection of Ad-mEndostatin significantly inhibited the tumor growth and metastasis, and prolonged the survival rate of mice (P < 0.05). Strong positive expression of mEndostatin was seen in the tumor tissue after injection of Ad-mEndostatin, immunhistochemically ostained by mouse endostatin monoclonal antibody, while the control groups showed only very low expression or absence. Serum endostatin concentration was 1540 +/- 560 ng/ml at the second week of administration, the expression of endostatin diminished a month later. The microvessel density (MVD)) decreased from 42.4 +/- 4.8 to 10.5 +/- 3.2 per x 200 magnificetion microscopic field by CD10 staining and from 68.5 +/- 4.5 to 37.5 +/- 4.6 by CD31 staining, respectively (P < 0.05). More apoptotic tumor cells were seen under the transmission electron microscope.

CONCLUSION

Endostatin gene therapy mediated by adenoviral vector efficiently induces expression of endostatin in vivo, and inhibits the growth and metastasis of tumor. It is concluded that its action is targeted to tumor neovasculature and the mechanism is inhibition of tumor angiogenesis.

[Angiogenesis in hypertrophic scar of rabbit ears and effect of extracellular protein with metalloprotease and thrombospondin 1 domains on hypertrophic scar]

OBJECTIVE

To investigate the angiogenesis in hypertropic scar tissue of rabbit ears at different periods and to explore a new method to prevent hyperplastic scar.

METHODS

Nineteen Japanese white rabbits (weigthing 2.0-2.5 kg) were made animal models of hypertropic scar of ear. At 10th, 30th, 60th and 90 days, after epithelization, the microvessel and microcirculation in hyperplastic scar of 8 rabbits were studied by microcirculation microscope and laser Doppler flowmetry. The other 11 rabbits' right or left ears were randomly chosen into experimental group and control group. At 10 days after epithelization, 40 microL of adenovirus extracellular protein with metalloprotease and thrombospondin 1 domains (Ad-METH1) was injected into tissue of scar along the perimeter of the scar in experimental group. The same volume of empty adenovirus was injected in control group. After 30 days of injection, the gross appearance of 10 rabbits' ears scar was recorded, the number of microvessel in scar was counted and HE stainning of scar tissue was performed in experimental and control groups. One additional rabbit was used to evaluate the mRNA and protein expression of METH1 by RT-PCR and Western blot after 3 days of injection.

RESULTS

The average number of microvessel at 10, 30, 60 and 90 days after epithelization was 42.37 +/- 3.89, 49.46 +/- 4.13, 33.12 +/- 4.34 and 13.24 +/- 2.31, respectively; the average value of microcirculatory perfusion at 10, 30, 60 and 90 days after epithetlization was (37.75 +/- 2.11), (59.87 +/- 6.46), (44.53 +/- 6.14) and (29.21 +/- 1.84) PU; the density of microvessels and perfusion of microcirculation in scar tissues during proliferative stage (from 10 to 60 days after epithelization) were markedly higher than that during mature period (90 days after epithelization, P < 0.05). At 10 to 30 days after epithelization, the histoligical features of scar showed early stage of proliferation and proliferative stage appearance; at 60 days after epithelization, it is still in proliferative stage, while some of scars were in mature phase; at 90 days after epithelization, the histoligical features of scar were mature period appearance. At 3 days after Ad-METH1 injection, METH1 gene was successfully expressed at both mRNA and protein levels in experimental group, but not in control group. At 30 days after injection, the gross appearance observation showed that scars in experimental group were flat and soft with the color close to normal, but scars in control group were obvious and hard. The number of microvessel of scar tissue was 12.38 +/- 2.56 in experimental group and 48.12 +/- 6.46 in control group, showing statistically significant difference between two groups (P < 0.01). In experimental group, HE staining shows that the density of microvessel and the number of fibroblasts were greatly decreased and collagen fibers arranged regularly. In control group, plenty of fibroblasts and abundant microvessels were observed. Thick and tight collagen fibers were seen in the outer layer of dermis with a irregular arrangement.

CONCLUSION

The anti-angiogenesis by Ad-METH1 may have a promising application in the prevention of human hyperthropic scar.

Subconjunctival injection of recombinant AAV-angiostatin ameliorates alkali burn induced corneal angiogenesis

PURPOSE

To evaluate the effect of subconjunctival injection of recombinant adeno-associated virus (rAAV)-angiostatin in alkali burn-induced corneal angiogenesis.

METHODS

Adeno-associated viral vector-mediated gene delivery into extraocular tissue was determined by fluorescent microscopy three weeks after subconjunctival injection of viral vector expressing green fluorescent protein (rAAV-GFP). Subconjunctival injection of recombinant adeno-associated viral vector expressing human angiostatin (rAAV-angiostatin) and blank rAAV viral vector (control) was performed in the left eye of male Sprague-Dawley rats (n=6). Alkaline induction of corneal neovascularization (NV) was performed three weeks later. Corneal NV regression was analyzed 7-14 days after alkali burn with slit lamp and digital pictures. Transgenic expression of angiostatin in the cornea, conjunctiva, retina, and muscle insertions was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Transgenic GFP gene expression was detected mainly in the muscle fibers at the extraocular muscle (EOM) insertions after subconjunctival injection. The area of corneal neovascularization was significantly lower in eyes injected with rAAV-angiostatin (p<0.01) than in eyes injected with the control virus. RT-PCR demonstrated that the angiostatin gene expression was highly detectable in muscle fibers and not detectable in the conjunctiva, cornea, and retina.

CONCLUSIONS

Subconjunctival injection of rAAV-angiostatin reduced alkali burn-induced corneal angiogenesis. We proved the concept that ocular gene therapy by subconjunctival injection of adenovirus-associated gene transfer of angiogenesis inhibitors can be a simple and safe treatment modality that can achieve therapeutic levels and long lasting effects in the treatment of corneal NV induced by ocular surface disorders.

[Inhibitory effect of combined transfection of p53 and AS genes on K562 cell proliferation]

This study was aimed to investigate the inhibitory effect of combined transfection of p53 and angiostatin (AS) genes on K562 cells and to explore its mechanism. pVTRIO2-hp53-hAS was transfected into K562 cells with lipofectamine 2000, RT-PCR was used to determine the expression of gene of interest in transfected cells, MTT growth curve and flow cytometry were used to analyze the cell cycle for observation biological changes of cells, the cellular immunochemistry assay was used to observe the expression differences between VEGF, Bcl-2 and Bax proteins. The results indicated that the genes of interest have been transfected and stably expressed, the increase of K562 with genes of interest was slower than that without genes of interest (p<0.05). And the increase of K562 in double gene group was slower than that in p53 and AS groups (0.264+/-0.011 at last day A290 nm; 0.652+/-0.039 at last day A290 nm; 0.604+/-0.017 at last day A290 nm respectively) (p<0.05). After transfection, the expressions of VEGF and Bcl-2 protein decreased, but the expressions of Bax increased. It is concluded that the combined transfection of p53 and AS genes into K562 cells shows more notable and powerful inhibition on proliferation than those transfected with single one gene. The synergistic mechanism of p53 and AS genes may be commonly influenced the pathway of Bcl-2 and Bax expression.

Inhibition of Tumor Growth and Metastasis Establishment by Adenovirus-mediated Gene Transfer Delivery of the Antiangiogenic Factor 16K hPRL

Tumor metastases, the most fearsome aspect of cancer, are generally resistant to conventional therapies. Angiogenesis is a crucial aspect of tumor growth and metastatic dissemination. Antiangiogenic therapy, therefore, holds potential as an attractive strategy for inhibiting metastasis development. Human 16K PRL (16K hPRL), a potent inhibitor of angiogenesis, has been demonstrated to prevent tumor growth in two xenograft mouse models, but whether it also affects tumor metastasis is unknown. In this study we will investigate the ability of 16K hPRL to prevent the establishment of metastasis. We demonstrate that 16K hPRL administered via adenovirus-mediated gene transfer, inhibits tumor growth by 86% in a subcutaneous (SC) B16-F10 mouse melanoma model. Computer-assisted image analysis shows that 16K hPRL treatment results in a reduction of tumor-vessel length and width, leading to a 57% reduction of average vessel size. In a pre-established tumor model, moreover, 16K hPRL can significantly delay tumor development. Finally, for the first time, we provide evidence that 16K hPRL considerably reduces the establishment of B16-F10 metastasis in an experimental lung metastasis model. Both the number and size of metastases are reduced by 50% in 16K hPRL-treated mice. These results highlight a potential role for 16K hPRL in anticancer therapy for both primary tumors and metastases.

A new approach to control condylar growth by regulating angiogenesis

OBJECTIVE

To provide a comprehensive review of the mechanisms of growth of mandibular condyle, the roles of angiogenesis enhancers and inhibitors during endochondral ossification in mandibular condyle and newly developed delivery methods for local gene delivery that may represent strategies to regulate condylar growth.

DESIGN

Narrative review.

RESULTS

Angiogenesis is the crucial step in mandibular condylar growth for it regulates the transformation from cartilage to bone. Angiognesis enhancers, especially VEGF and FGF, play important roles in the process of new blood lumen formation and invasion. On the other hand, angiostatin and endostatin inhibit angiogenesis by targeting endothelial cells and several signal cascades. Delivery methods such as liposomes, stem cells and virus vectors have been studied. Recombinant AAV-mediated gene therapy is considered as one of the most promising strategies of condylar growth management.

CONCLUSION

AAV-mediated gene therapy using VEGF or angiogenesis inhibitor will be a promising way to regulate condylar growth at an early stage.

In vivo inhibition of angiogenesis by interleukin-13 gene therapy in a rat model of rheumatoid arthritis

OBJECTIVE

Interleukin-13 (IL-13) is a pleiotropic cytokine that can affect vessel formation, an important component of the rheumatoid arthritis (RA) synovial tissue pannus. The purpose of this study was to use a gene therapy approach to investigate the role of IL-13 in angiogenesis in vivo, using a rat adjuvant-induced arthritis model of RA.

METHODS

Ankle joints of female rats were injected preventatively with an adenovirus vector containing human IL-13 (AxCAIL-13), a control vector with no insert (AxCANI), or phosphate buffered saline (PBS). Joints were harvested at the peak of arthritis, and histologic and biochemical features were evaluated.

RESULTS

AxCAIL-13-treated joint homogenates had lower hemoglobin levels, suggesting reduced joint vascularity, and both endothelial cell migration and tube formation were significantly inhibited (P < 0.05). Similarly, AxCAIL-13 inhibited capillary sprouting in the rat aortic ring assay and vessel growth in the Matrigel plug in vivo assay. IL-13 gene delivery resulted in up-regulation and association of phosphorylated ERK-1/2 and protein kinase Calpha/betaII, suggesting a novel pathway in IL-13-mediated angiostasis. The angiostatic effect of AxCAIL-13 was associated with down-regulation of proangiogenic cytokines (IL-18, cytokine-induced neutrophil chemoattractant 1/CXCL1, lipopolysaccharide-induced CXC chemokine/CXCL5) and up-regulation of the angiogenesis inhibitor endostatin. The expression and activity of matrix metalloproteinases 2 and 9, which participate in angiogenesis, was impaired in response to IL-13 as compared with AxCANI and PBS treatment.

CONCLUSION

Our findings support a role for IL-13 as an in vivo antiangiogenic factor and provide a rationale for its use in RA to control pathologic neovascularization.

Inhibition of angiogenesis and HCT-116 xenograft tumor growth in mice by kallistatin

AIM: To investigate the inhibitory effect of kallistatin (KAL) on angiogenesis and HCT-116 xenograft tumor growth.

METHODS: Heterotopic tumors were induced by subcutaneous injection of 2 × 10⁶ HCT-11 cells in mice. Seven days later, 2 × 10¹¹ rAAV-GFP or rAAV-KAL was injected intratumorally (n = 5 for each group). The mice were sacrificed at d 28, by which time the tumors in the rAAV-GFP group had grown to beyond 5% of the total body weight. Tumor growth was measured by calipers in two dimensions. Tumor angiogenesis was determined with tumor microvessel density (MVD) by immunohistology. Tumor cell proliferation was assessed by Ki-67 staining.

RESULTS: Intratumor injection of rAAV-KAL inhibited tumor growth in the treatment group by 78% (171 ± 52 mm³) at d 21 after virus infection compared to the control group (776 ± 241 mm³). Microvessel density was significantly inhibited in tumor tissues treated with rAAV-KAL. rAAV-KAL also decreased the proportion of proliferating cells (Ki-67 positive cells) in tumors compared with the control group.

CONCLUSION: rAAV-mediated expression of KAL inhibits the growth of colon cancer by reducing angiogenesis and proliferation of tumor cells, and may provide a promising anti-angiogenesis-based approach to the treatment of metastatic colorectal cancer.

Disease susceptibility of the human macula: Differential gene transcription in the retinal pigmented epithelium/choroid

The discoveries of gene variants associated with macular diseases have provided valuable insight into their molecular mechanisms, but they have not clarified why the macula is particularly vulnerable to degenerative disease. Its predisposition may be attributable to specialized structural features and/or functional properties of the underlying macular RPE/choroid. To examine the molecular basis for the macula's disease susceptibility, we compared the gene expression profile of the human RPE/choroid in the macula with the profile in the extramacular region using DNA microarrays. Seventy-five candidate genes with differences in macular:extramacular expression levels were identified by microarray analysis, of which 29 were selected for further analysis. Quantitative PCR confirmed that 21 showed statistically significant differences in expression. Five genes were expressed at higher levels in the macula. Two showed significant changes in the macular:extramacular expression ratio; another two exhibited changes in absolute expression level, as a function of age or AMD. Several of the differentially expressed genes have potential relevance to AMD pathobiology. One is an RPE cell growth factor (TFPI2), five are extracellular matrix components (DCN, MYOC, OGN, SMOC2, TFPI2), and six are related to inflammation (CCL19, CCL26, CXCL14, SLIT2) and/or angiogenesis (CXCL14, SLIT2, TFPI2, WFDC1). The identification of regional differences in gene expression in the RPE/choroid is a first step in clarifying the macula's propensity for degeneration. These findings lay the groundwork for further studies into the roles of the corresponding gene products in the normal, aged, and diseased macula.

[Constitutive expression of human angiostatin in Pichia pastoris using glycerol as only carbon source]

Carbon source plays an important role in the constitutive expression of foreign proteins in Pichia pastoris. In present study, glucose , glycerol , methanol and oil acid, was used respectively as the only carbon source to constitutively express hAS in Pichia pastoris GS115 (pGAP9K-AS)in shaking flask. The result shows that oleic acid is the best (163 mg/L) compared with glycerol (83mg/L), glucose (76 mg/L)and methanol (57 mg/L). Since oleic acid is insoluble in water, glycerol was used as the carbon source in the high-density cell culture of GS115 (pGAP9K-AS) in a 30 liter bioreactor and 169 mg/L of angiostatin was obtained after 48h of culture. The expressed angiostatin is immunologically active as shown by Western blotting. The recombinant hAS inhibits bFGF induced CAM angiogenesis and suppresses the growth of B16 melanoma in C57BL/6J mice. The tumor inhibition rate is 90% after 12 days of treatment. Statistics analysis revealed that the tumor volume difference of mice between the hAS group and PBS group is prominent (P < 0.01).