Experimental study on anti angiogenesis of recombinant mouse angiostatin gene in mice with gallbladder carcinoma.

Gallbladder cancer is one of the gastrointestinal tumors with an extremely poor prognosis. Its incidence rate is gradually increasing worldwide, and the rate of radical resection surgery is extremely low. Not sensitive to radiotherapy and chemotherapy, with a very poor prognosis. This study aimed to investigate whether the recombinant mouse angiostatin gene transfected anti-angiogenic gallbladder cancer cells can express angiostatin protein with the activity of inhibiting the growth of vascular endothelial cells and the inhibitory effect on the growth of gallbladder cancer. The recombinant mouse angiostatin gene eukaryotic expression plasmid was transfected into the gallbladder cancer cell line by applying liposome LIPOFECTAMINE 2000, and its activity was detected by vascular endothelial cell proliferation analysis. The results show that angiostatin can inhibit the growth of transplanted gallbladder cancer, and as the number of injections increases, the inhibition rate of gallbladder cancer growth also increases. At the end of the experiment, the total inhibition rate of gallbladder cancer growth reached 95% 5%, 20%, 30%, 40% gradually increase. Therefore, angiostatin has potential clinical application value in gene therapy of gallbladder cancer.

Synergistic Effect of Baculovirus-Mediated Endostatin and Angiostatin Combined with Gemcitabine in Hepatocellular Carcinoma.

Anti-angiogenic gene therapy is a promising strategy in treating cancer. Endostatin and angiostatin are widely used in tumor anti-angiogenesis therapy. Our previous studies have shown that the BDS-hEA, a baculovirus long-term expressing the fusion protein of human endostatin and angiostatin, has a favorable effect in inhibiting the growth and angiogenesis of hepatocellular carcinoma. The purpose of this study was to further investigate its synergistic antitumor efficiency in combination with low-dose chemotherapeutic gemcitabine (GEM) on the subcutaneous hepatocellular carcinoma xenograft model in nude mice. The results showed that the combined group significantly inhibited (p < 0.05 or p < 0.01 or p < 0.001) the growth of tumor weight and volume, reduced the expression of ki67 (cell proliferation marker), CD31 (angiogenic marker) and Matrix metalloproteinase 9 (MMP-9, tumor invasion and metastasis marker) and increased the apoptosis of tumor cells compared with the monotherapy and control groups, respectively. Synergistic index results showed that BDS-hEA combined with GEM had a synergistic effect in inhibiting tumor volume, proliferation, microvessel density, metastasis and promoting tumor apoptosis. Furthermore, there were no metastatic nodules and obvious pathological changes in liver tissue of the combined group, and the serum liver function indicators aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (T-BIL), alkaline phosphatase (ALP) and glutamyl transpeptidase (GGT) were significantly reduced (p < 0.05 or p < 0.01 or p < 0.001) in the BDS-hEA or GEM groups compared with the control group. Notably, the combined therapy showed lower levels of liver function indicators than the GEM group. These data support the view that the combination of BDS-hEA and GEM has a synergistic anti-tumor properties and can reduce the damage of liver to certain extent.

Development of a novel bivalent baculovirus vectors for complement resistance and sustained transgene expression and its application in anti-angiogenesis gene therapy.

Baculovirus (BV) is a potential gene delivery vector but only mediates transient transgene expression and easily inactivated by human complement. To this end, we intend to develop a novel bivalent BV vector for complement resistance and sustained transgene expression, and evaluate its effect in anti-angiogenesis gene therapy. The results showed that the hybrid bivalent BV significantly prolonged the expression of enhanced green fluorescent protein (eGFP) in vitro for at least 90 days at over 109 a.u. total fluorescence intensity, and exhibited significantly higher complement resistance. The control BV-mediated eGFP expression gradually declined within 15 days and showed lower transduction efficiency. In vivo studies confirmed that the hybrid bivalent BV exhibited longer duration of eGFP expression and higher transduction efficacy than the control BVs. Based on these findings, we further constructed a hybrid BV expressing the antiangiogenic fusion protein containing human endostatin and angiostatin (hEA). The hybrid BV-expressed hEA significantly prolonged the expression level of hEA with enhanced anti-angiogenic activities compared to the control groups, as evidenced by ELISA, cell proliferation, migration and tubular formation assays. With the stable expression of hEA, the hybrid BV conferred hEA more significant inhibitory effect on hepatocellular carcinoma tumor growth and significantly extended the life span of mice. These data implicate that the SB-based BV surface display system may have broad prospects as a novel platform for gene therapy of tumors.

Extracellular anti-angiogenic proteins augment an endosomal protein trafficking pathway to reach mitochondria and execute apoptosis in HUVECs.

Classic endocytosis destinations include the recycling endosome returning to the plasma membrane or the late endosome (LE) merging with lysosomes for cargo degradation. However, the anti-angiogenic proteins angiostatin and isthmin, are endocytosed and trafficked to mitochondria (Mito) to execute apoptosis of endothelial cells. How these extracellular proteins reach mitochondria remains a mystery. Through confocal and super-resolution fluorescent microscopy, we demonstrate that angiostatin and isthmin are trafficked to mitochondria through the interaction between LE and Mito. Using purified organelles, the LE-Mito interaction is confirmed through in vitro lipid-fusion assay, as well as single vesicle total internal reflection fluorescent microscopy. LE-Mito interaction enables the transfer of not only lipids but also proteins from LE to Mito. Angiostatin and isthmin augment this endosomal protein trafficking pathway and make use of it to reach mitochondria to execute apoptosis. Cell fractionation and biochemical analysis identified that the cytosolic scaffold protein Na+/H+ exchanger regulatory factor 1 (NHERF1) associated with LE and the t-SNARE protein synaptosome-associated protein 25 kDa (SNAP25) associated with Mito form an interaction complex to facilitate LE-Mito interaction. Proximity ligation assay coupled with fluorescent microscopy showed that both NHERF1 and SNAP25 are located at the contacting face between LE and Mito. RNAi knockdown of either NHERF1 or SNAP25 suppressed not only the mitochondrial trafficking of angiostatin and isthmin but also their anti-angiogenic and pro-apoptotic functions. Hence, this study reveals a previously unrealized endosomal protein trafficking pathway from LE to Mito that allows extracellular proteins to reach mitochondria and execute apoptosis.

Lentiviral Vector Gene Transfer of Endostatin/Angiostatin for Macular Degeneration (GEM) Study.

Neovascular age-related macular degeneration (NVAMD) is a prevalent cause of vision loss. Intraocular injections of VEGF-neutralizing proteins provide benefit, but many patients require frequent injections for a prolonged period. Benefits are often lost over time due to lapses in treatment. New treatments that sustain anti-angiogenic activity are needed. This study tested the safety and expression profile of a lentiviral Equine Infectious Anemia Virus (EIAV) vector expressing endostatin and angiostatin (RetinoStat®). Patients with advanced NVAMD were enrolled at three centers in the United States, and the study eye received a subretinal injection of 2.4 × 104 (n = 3), 2.4 × 105 (n = 3), or 8.0 × 105 transduction units (TU; n = 15). Each of the doses was well-tolerated with no dose-limiting toxicities. There was little or no ocular inflammation. There was one procedure-related serious adverse event (AE), a macular hole, which was managed without difficulty and resolved. There was a vector dose-related increase in aqueous humor levels of endostatin and angiostatin with high reproducibility among subjects within cohorts. Mean levels of endostatin and angiostatin peaked between 12 and 24 weeks after injection of 2.4 × 105 TU or 8.0 × 105 TU at 57-81 ng/mL for endostatin and 15-27 ng/mL for angiostatin, and remained stable through the last measurement at week 48. Long-term follow-up demonstrated expression was maintained at last measurement (2.5 years in eight subjects and >4 years in two subjects). Despite an apparent reduction in fluorescein angiographic leakage that broadly correlated with the expression levels in the majority of patients, only one subject showed convincing evidence of anti-permeability activity in these late-stage patients. There was no significant change in mean lesion size in subjects injected with 8.0 × 105 TU. These data demonstrate that EIAV vectors provide a safe platform with robust and sustained transgene expression for ocular gene therapy.

Aerobic training and l-arginine supplementation promotes rat heart and hindleg muscles arteriogenesis after myocardial infarction.

Arteriogenesis is a main defense mechanism to prevent heart and local tissues dysfunction in occlusive artery disease. TGF-ß and angiostatin have a pivotal role in arteriogenesis. We tested the hypothesis that aerobic training and l-arginine supplementation promotes cardiac and skeletal muscles arteriogenesis after myocardial infarction (MI) parallel to upregulation of TGF-ß and downregulation of angiostatin. For this purpose, 4 weeks after LAD occlusion, 50 male Wistar rats were randomly distributed into five groups: (1) sham surgery without MI (sham, n = 10), (2) control-MI (Con-MI, n = 10), (3) l-arginine-MI (La-MI, n = 10), (4) exercise training-MI (Ex-MI, n = 10), and (5) exercise and l-arginine-MI (Ex + La-MI). Exercise training groups running on a treadmill for 10 weeks with moderate intensity. Rats in the l-arginine-treated groups drank water containing 4 % l-arginine. Arteriolar density with different diameters (11-25, 26-50, 51-75, and 76-150 µm), TGF-ß, and angiostatin gene expression were measured in cardiac (area at risk) and skeletal (soleus and gastrocnemius) muscles. Smaller arterioles decreased in cardiac after MI. Aerobic training and l-arginine increased the number of cardiac arterioles with 11-25 and 26-50 µm diameters parallel to TGF-ß overexpression. In gastrocnemius muscle, the number of arterioles/mm(2) was only increased in the 11 to 25 µm in response to training with and without l-arginine parallel to angiostatin downregulation. Soleus arteriolar density with different size was not different between experimental groups. Results showed that 10 weeks aerobic exercise training and l-arginine supplementation promotes arteriogenesis of heart and gastrocnemius muscles parallel to overexpression of TGF-ß and downregulation of angiostatin in MI rats.

Combinatorial anti-angiogenic gene therapy in a human malignant mesothelioma model.

Anti-angiogenic gene therapy represents a promising strategy for cancer; however, it has rarely been tested in malignant mesothelioma, a highly aggressive tumor associated with asbestos with poor prognosis. In the present study, we investigated whether anti-angiogenic factors such as angiostatin, endostatin and the soluble form of vascular endothelial growth factor receptor 2 (sFlk1) were able to inhibit endothelial cell proliferation via lentivirus-mediated gene transfer into malignant mesothelioma cells in culture. We also assessed whether a dual-agent strategy had greater therapeutic benefit. Human malignant pleural mesothelioma MSTO-211H cells were transduced using lentiviral vectors that individually expressed angiostatin, endostatin and sFlk1 and linked to enhanced green fluorescent protein (EGFP) marker gene expression via an internal ribosome entry site. The lentivirus expressing EGFP alone was used as a control. The resultant cells designated as MSTO-A, MSTO-E, MSTO-F and MSTO-C were confirmed by western blot analysis and fluorescence microscopy to stably express the corresponding proteins. No differences were observed in the in vitro growth rates between any of these cells. However, co-culture of MSTO-A, MSTO-E and MSTO-F showed significant suppression of human umbilical endothelial cell growth in vitro compared with that of MSTO-C. Furthermore, a combination of any two among MSTO-A, MSTO-E and MSTO-F significantly enhanced efficacy. These results suggest that combinatorial anti-angiogenic gene therapy targeting different pathways of endothelial growth factor signaling has the potential for greater therapeutic efficacy than that of a single-agent regimen.

Enhanced antitumor efficacy of an oncolytic herpes simplex virus expressing an endostatin-angiostatin fusion gene in human glioblastoma stem cell xenografts.

Viruses have demonstrated strong potential for the therapeutic targeting of glioblastoma stem cells (GSCs). In this study, the use of a herpes simplex virus carrying endostatin-angiostatin (VAE) as a novel therapeutic targeting strategy for glioblastoma-derived cancer stem cells was investigated. We isolated six stable GSC-enriched cultures from 36 human glioblastoma specimens and selected one of the stable GSCs lines for establishing GSC-carrying orthotopic nude mouse models. The following results were obtained: (a) VAE rapidly proliferated in GSCs and expressed endo-angio in vitro and in vivo 48 h and 10 d after infection, respectively; (b) compared with the control gliomas treated with rHSV or Endostar, the subcutaneous gliomas derived from the GSCs showed a significant reduction in microvessel density after VAE treatment; (c) compared with the control, a significant improvement was observed in the length of the survival of mice with intracranial and subcutaneous gliomas treated with VAE; (d) MRI analysis showed that the tumor volumes of the intracranial gliomas generated by GSCs remarkably decreased after 10 d of VAE treatment compared with the controls. In conclusion, VAE demonstrated oncolytic therapeutic efficacy in animal models of human GSCs and expressed an endostatin-angiostatin fusion gene, which enhanced antitumor efficacy most likely by restricting tumor microvasculature development.

Suppression of neovascularization of donor corneas by transduction with equine infectious anemia virus-based lentiviral vectors expressing endostatin and angiostatin.

Corneal transplantation is the oldest and one of the most successful transplant procedures with a success rate in many studies in excess of 90%. The high success rate is mainly attributable to the relatively immune-privileged status of the eye and the fact that the cornea is largely avascular. However, the success rate in patients with failed grafts is much lower such that regrafting is frequently the top indication for corneal transplantation in many centers. Neovascularization is the most important risk factor for rejection, as it allows access of the immune system to the donor tissue, compromising immune privilege of the graft/eye. We have developed a process to modify donor corneal tissue to prevent rejection by a single exposure to a gene therapy vector before surgery (EncorStat(®)). The vector used is based on clinically relevant equine infectious anemia virus (EIAV)-derived lentiviral platform and contains genes for two potently angiostatic genes, endostatin and angiostatin. We show that incubation of rabbit, primate, and human corneal tissue with the EIAV vector mediates strong, stable expression in the corneal endothelium. We have optimized this process to maximize transduction and, once this is complete, maximize the removal of free vector before transplant. Rabbit corneas treated with two different antiangiogenic expression vectors (EIAV-EndoAngio and to a lesser extent EIAV-Endo:k5) significantly suppressed neovascularization in a rabbit model of corneal rejection. As a result, corneal opacity, edema, and inflammatory infiltrates were reduced in these corneas. This study demonstrates that angiogenesis is a suitable target to prevent corneal rejection, and provides the first proof-of-concept data for the development of EncorStat, an ex vivo gene therapy treatment to prevent corneal rejection.

Combination of oncolytic herpes simplex viruses armed with angiostatin and IL-12 enhances antitumor efficacy in human glioblastoma models.

Oncolytic herpes simplex virus (oHSV) can potentially spread throughout the tumor, reach isolated infiltrating cells, kill them, and deliver anticancer agents. However, the host responds to oHSV by inducing intratumoral infiltration of macrophages that can engulf the virus, limiting the potential of this therapeutic strategy. Hypervascularity is a pathognomonic feature of glioblastoma (GBM) and is a promising therapeutic target. Antiangiogenic treatments have multiple benefits, including the capacity to increase oHSV efficacy by suppressing macrophage extravasation and infiltration into the tumor. Angiostatin is an antiangiogenic polypeptide, and interleukin-12 (IL-12) is an immunostimulatory cytokine with strong antiangiogenic effects. Clinical use of each has been limited by delivery issues and systemic toxicity. We tested a combination treatment strategy using oHSVs expressing angiostatin (G47Δ-mAngio) and IL-12 (G47Δ-mIL12) in two orthotopic human GBM models. Intratumoral injection of G47Δ-mAngio and G47Δ-mIL12 in mice bearing intracranial U87 or tumors derived from glioblastoma stem cells significantly prolonged survival compared to each armed oHSV alone. This was associated with increased antiangiogenesis and virus spread and decreased macrophages. These data support the paradigm of using oHSV expressing different antiangiogenic agents and show for the first time that oHSVs expressing angiostatin and IL-12 can improve efficacy in human GBM models.

Transient repetitive exposure to low level light therapy enhances collateral blood vessel growth in the ischemic hindlimb of the tight skin mouse.

The tight skin mouse (Tsk(-/+)) is a model of scleroderma characterized by impaired vasoreactivity, increased oxidative stress, attenuated angiogenic response to VEGF and production of the angiogenesis inhibitor angiostatin. Low-level light therapy (LLLT) stimulates angiogenesis in myocardial infarction and chemotherapy-induced mucositis. We hypothesize that repetitive LLLT restores vessel growth in the ischemic hindlimb of Tsk(-/+) mice by attenuating angiostatin and enhancing angiomotin effects in vivo. C57Bl/6J and Tsk(-/+) mice underwent ligation of the femoral artery. Relative blood flow to the foot was measured using a laser Doppler imager. Tsk(-/+) mice received LLLT (670 nm, 50 mW cm(-2), 30 J cm(-2)) for 10 min per day for 14 days. Vascular density was determined using lycopersicom lectin staining. Immunofluorescent labeling, Western blot analysis and immunoprecipitation were used to determine angiostatin and angiomotin expression. Recovery of blood flow to the ischemic limb was reduced in Tsk(-/+) compared with C57Bl/6 mice 2 weeks after surgery. LLLT treatment of Tsk(-/+) mice restored blood flow to levels observed in C57Bl/6 mice. Vascular density was decreased, angiostatin expression was enhanced and angiomotin depressed in the ischemic hindlimb of Tsk(-/+) mice. LLLT treatment reversed these abnormalities. LLLT stimulates angiogenesis by increasing angiomotin and decreasing angiostatin expression in the ischemic hindlimb of Tsk(-/+) mice.

Synergistic antitumoral effect of IL-12 gene cotransfected with antiangiogenic genes for angiostatin, endostatin, and saxatilin.

Previously, it was reported that the cotransfection of angiostatin K1-3, endostatin, and saxatilin genes using cationic liposomes significantly inhibited tumor progression. IL-12 is a well-known immune modulator that promotes Th1-type antitumor immune responses and also induces antiangiogenic effects. In this study, we have examined the antitumoral function of the IL-12 gene cotransfected with antiangiogenic genes for angiostatin K1-3, endostatin, and saxatilin by O,O'-dimyristyl-N-lysyl glutamate (DMKE) cationic liposomes in a mouse tumor model. According to our results, the administration of the IL-12 gene or the genes for angiostatin K1-3, endostatin, and saxatilin exhibited effective inhibition of B16BL6 melanoma growth in mice. In particular, intravenous administration of the IL-12 gene along with intratumoral administration of the three antiangiogenic genes synergistically inhibited the B16BL6 tumor growth. These results suggest that systemically expressed IL-12 enhances antitumoral efficacy of locally expressed antiangiogenic proteins.

Safety and biodistribution of an equine infectious anemia virus-based gene therapy, RetinoStat(®), for age-related macular degeneration.

RetinoStat(®) is an equine infectious anemia virus-based lentiviral gene therapy vector that expresses the angiostatic proteins endostatin and angiostatin that is delivered via a subretinal injection for the treatment of the wet form of age-related macular degeneration. We initiated 6-month safety and biodistribution studies in two species; rhesus macaques and Dutch belted rabbits. After subretinal administration of RetinoStat the level of human endostatin and angiostatin proteins in the vitreous of treated rabbit eyes peaked at ∼1 month after dosing and remained elevated for the duration of the study. Regular ocular examinations revealed a mild to moderate transient ocular inflammation that resolved within 1 month of dosing in both species. There were no significant long-term changes in the electroretinograms or intraocular pressure measurements in either rabbits or macaques postdosing compared with the baseline reading in RetinoStat-treated eyes. Histological evaluation did not reveal any structural changes in the eye although there was an infiltration of mononuclear cells in the vitreous, retina, and choroid. No antibodies to any of the RetinoStat vector components or the transgenes could be detected in the serum from either species, and biodistribution analysis demonstrated that the RetinoStat vector was maintained within the ocular compartment. In summary, these studies found RetinoStat to be well tolerated, localized, and capable of persistent expression after subretinal delivery.

Mitochondrial division/mitophagy inhibitor (Mdivi) ameliorates pressure overload induced heart failure.

BACKGROUND: We have previously reported the role of anti-angiogenic factors in inducing the transition from compensatory cardiac hypertrophy to heart failure and the significance of MMP-9 and TIMP-3 in promoting this process during pressure overload hemodynamic stress. Several studies reported the evidence of cardiac autophagy, involving removal of cellular organelles like mitochondria (mitophagy), peroxisomes etc., in the pathogenesis of heart failure. However, little is known regarding the therapeutic role of mitochondrial division inhibitor (Mdivi) in the pressure overload induced heart failure. We hypothesize that treatment with mitochondrial division inhibitor (Mdivi) inhibits abnormal mitophagy in a pressure overload heart and thus ameliorates heart failure condition. MATERIALS AND METHODS: To verify this, ascending aortic banding was done in wild type mice to create pressure overload induced heart failure and then treated with Mdivi and compared with vehicle treated controls. RESULTS: Expression of MMP-2, vascular endothelial growth factor, CD31, was increased, while expression of anti angiogenic factors like endostatin and angiostatin along with MMP-9, TIMP-3 was reduced in Mdivi treated AB 8 weeks mice compared to vehicle treated controls. Expression of mitophagy markers like LC3 and p62 was decreased in Mdivi treated mice compared to controls. Cardiac functional status assessed by echocardiography showed improvement and there is also a decrease in the deposition of fibrosis in Mdivi treated mice compared to controls. CONCLUSION: Above results suggest that Mdivi inhibits the abnormal cardiac mitophagy response during sustained pressure overload stress and propose the novel therapeutic role of Mdivi in ameliorating heart failure.

Hydrogen sulfide mitigates cardiac remodeling during myocardial infarction via improvement of angiogenesis.

Exogenous hydrogen sulfide (H2S) leads to down-regulation of inflammatory responses and provides myocardial protection during acute ischemia/reperfusion injury; however its role during chronic heart failure (CHF) due to myocardial infarction (MI) is yet to be unveiled. We previously reported that H2S inhibits antiangiogenic factors such, as endostatin and angiostatin, but a little is known about its effect on parstatin (a fragment of proteinase-activated receptor-1, PAR-1). We hypothesize that H2S inhibits parstatin formation and promotes VEGF activation, thus promoting angiogenesis and significantly limiting the extent of MI injury. To verify this hypothesis MI was created in 12 week-old male mice by ligation of left anterior descending artery (LAD). Sham surgery was performed except LAD ligation. After the surgery mice were treated with sodium hydrogen sulfide (30 µmol/l NaHS, a donor for H2S, in drinking water) for 4 weeks. The LV tissue was analyzed for VEGF, flk-1 and flt-1, endostatin, angiostatin and parstatin. The expression of VEGF, flk-1 and flt-1 were significantly increased in treated mice while the level of endostatin, angiostatin and parstatin were decreased compared to in untreated mice. The echocardiography in mice treated with H2S showed the improvement of heart function compared to in untreated mice. The X-ray and Doppler blood flow measurements showed enhancement of cardiac-angiogenesis in mice treated with H2S. This observed cytoprotection was associated with an inhibition of anti-angiogenic proteins and stimulation of angiogenic factors. We established that administration of H2S at the time of MI ameliorated infarct size and preserved LV function during development of MI in mice. These results suggest that H2S is cytoprotective and angioprotective during evolution of MI.

Bevacizumab with angiostatin-armed oHSV increases antiangiogenesis and decreases bevacizumab-induced invasion in U87 glioma.

Bevacizumab (BEV) is an antiangiogenic drug approved for glioblastoma (GBM) treatment. However, it does not increase survival and is associated with glioma invasion. Angiostatin is an antiangiogenic polypeptide that also inhibits migration of cancer cells, but is difficult to deliver. Oncolytic viruses (OV) can potentially spread throughout the tumor, reach isolated infiltrating cells, kill them and deliver anticancer agents to uninfected cells. We have tested a combination treatment of BEV plus an OV expressing angiostatin (G47Δ-mAngio) in mice-bearing human GBM. Using a vascular intracranial human glioma model (U87) in athymic mice, we performed histopathological analysis of tumors treated with G47Δ-mAngio or BEV alone or in combination, followed tumor response by magnetic resonance imaging (MRI), and assessed animal survival. Our results indicate that injection of G47Δ-mAngio during BEV treatment allows increased virus spread, tumor lysis, and angiostatin-mediated inhibition of vascular endothelial growth factor (VEGF) expression and of BEV-induced invasion markers (matrix metalloproteinases-2 (MMP2), MMP9, and collagen). This leads to increased survival and antiangiogenesis and decreased invasive phenotypes. We show for the first time the possibility of improving the antiangiogenic effect of BEV while decreasing the tumor invasive-like phenotype induced by this drug, and demonstrate the therapeutic advantage of combining systemic and local antiangiogenic treatments with viral oncolytic therapy.

Gene transfer for ocular neovascularization and macular edema.

Diseases complicated by abnormal growth of vessels or excessive leakage are the most prevalent cause of moderate or severe vision loss in developed countries. Recent progress unraveling the molecular pathogenesis of several of these disease processes has led to new drug therapies that have provided major benefits to patients. However, those treatments often require frequent intraocular injections, and despite monthly injections, some patients have a suboptimal response. Gene transfer of antiangiogenic proteins is an alternative approach that has the potential to provide long-term suppression of neovascularization (NV) and/or excessive vascular leakage in the eye. Studies in animal models of ocular NV have demonstrated impressive results with a number of transgenes, and a clinical trial in patients with advanced neovascular age-related macular degeneration has provided proof-of-concept. Two ongoing clinical trials, one using an adeno-associated viral (AAV) vector to express a vascular endothelial growth factor-binding protein and another using a lentiviral vector to express endostatin and angiostatin, will provide valuable information that should help to inform future trials and provide a foundation on which to build.

Linoleic acid enhances angiogenesis through suppression of angiostatin induced by plasminogen activator inhibitor 1.

BACKGROUND: The intake of dietary fatty acids is highly correlated with the risk of various cancers. Linoleic acid (LA) is the most abundant polyunsaturated fat in the western diet, but the mechanism(s) by fatty acids such as LA modulate cancer cells is unclear. In this study, we examined the role of LA in various steps in gastric cancer progression. METHODS: The difference in gene expression between LA-treated and untreated OCUM-2MD3 gastric carcinoma cells was examined by mRNA differential display. The involvement of candidate genes was examined by oligo- and plasmid-mediated RNA interference. Biological functions of several of these genes were examined using in vitro assays for invasion, angiogenesis, apoptosis, cell viability, and matrix digestion. Angiogenesis in vivo was measured by CD-31 immunohistochemistry and microvessel density scoring. RESULTS: LA enhanced the plasminogen activator inhibitor 1 (PAI-1) mRNA and protein expression, which are controlled by PAI-1 mRNA-binding protein. LA-stimulated invasion depended on PAI-1. LA also enhanced angiogenesis by suppression of angiostatin, also through PAI-1. LA did not alter cell growth in culture, but increased dietary LA-enhanced tumour growth in an animal model. CONCLUSION: Our findings suggest that dietary LA impacts multiple steps in cancer invasion and angiogenesis, and that reducing LA in the diet may help slow cancer progression.

Baculovirus vectors for antiangiogenesis-based cancer gene therapy.

Baculovirus is an insect virus that is non-pathogenic to humans and has emerged as a promising gene therapy vector. Since solid tumor growth/metastasis critically relies on angiogenesis and hEA, a fusion protein comprising human endostatin and angiostatin, exhibits potent antiangiogenic and antitumor efficacy in mouse models; this study aimed to evaluate the feasibility of baculovirus for hEA expression and antiangiogenesis-based cancer gene therapy. Toward this end, we constructed Bac-hEA that mediated transient hEA expression and Bac-ITR-hEA that exploited the adeno-associated virus inverted terminal repeats (ITRs) for prolonged hEA expression. Western blot and ELISA analyses showed that both Bac-hEA and Bac-ITR-hEA expressed hEA in transduced mammalian cells, yet Bac-ITR-hEA only marginally prolonged the hEA expression. In comparison with Bac-hEA, nonetheless, Bac-ITR-hEA significantly enhanced the hEA expression level that concurred with augmented antiangiogenic properties, as demonstrated by cell proliferation, migration and tubule network formation assays. Importantly, intratumoral injection of Bac-ITR-hEA into prostate cancer mouse models, when compared with Bac-hEA, exerted stronger antiangiogenic effects in vivo, more potently inhibited tumor growth and significantly prolonged mouse survival. This study collectively supported the notion that hEA is an effective antiangiogenic protein and proved the potential of baculovirus as a vector for antiangiogenesis-based cancer therapy, which may be combined with chemotherapy, radiotherapy or gene therapies using other vectors.