Recombinant human endostatin as a potential anti-angiogenic agent: therapeutic perspective and current status.

Angiogenesis is the physiological process that results in the formation of new blood vessels develop from pre-existing vasculature and plays a significant role in several physiological and pathological processes. Inhibiting angiogenesis, a crucial mechanism in the growth and metastasis of cancer, has been proposed as a potential anticancer therapy. Different studies showed the beneficial effects of angiogenesis inhibitors either in patients suffering from different cancers, alone or in combination with conventional therapies. Even though there are currently a number of efficient anti-angiogenic drugs, including monoclonal antibodies and kinase inhibitors, the associated toxicity profile and their affordability constraints are prompting researchers to search for a safe and affordable angiostatic agent for cancer treatment. Endostatin is one of the endogenous anti-angiogenic candidates that have been extensively pursued for the treatment of cancer, but even over three decades after its discovery, we have not made much advancement in employing it as an anticancer therapeutic despite of its remarkable anti-angiogenic effect with low toxicity profile. A recombinant human endostatin (rh-Es) variant for non-small cell lung cancer was approved by China in 2006 and has since been used effectively. Several other successful clinical trials related to endostatin for various malignancies are either ongoing or have already been completed with promising results. Thus, in this review, we have provided an overview of existing anti-angiogenic drugs developed for cancer therapy, with a summary of tumour angiogenesis in the context of Endostatin, and clinical status of rh-Es in cancer treatment. Furthermore, we briefly discuss the various strategies to improve endostatin features (poor pharmacokinetic properties) for developing rh-Es as a safe and effective agent for cancer treatment.

Exploring the molecular role of endostatin in diabetic neuropathy.

For over a decade, diabetic neuropathy has exhibited great emergence in diabetic patients. Though there are numerous impediments in understanding the underlying pathology it is not that enough to conclude. Initially, there was no intricate protocol for diagnosis as its symptoms mimic most of the neurodegenerative disorders and demyelinating diseases. Continuous research on this, reveals many pathological correlates which are also detectable clinically. The most important pathologic manifestation is imbalanced angiogenesis/neo-vascularization. This review is completely focused on established pathogenesis and anti-angiogenic agents which are physiological signal molecules by the origin. Those agents can also be used externally to inhibit those pathogenic pathways. Pathologically DN demonstrates the misbalanced expression of many knotty factors like VEGF, FGF2, TGFb, NF-kb, TNF-a, MMP, TIMP, and many minor factors. Their pathway towards the incidence of DN is quite interrelated. Many anti-angiogenic agents inhibit neovascularization to many extents, but out of them predominantly inhibition of angiogenic activity is shared by endostatin which is now in clinical trial phase II. It inhibits almost all angiogenic factors and it is possible because they share interrelated pathogenesis towards imbalanced angiogenesis. Endostatin is a physiological signal molecule produced by the proteolytic cleavage of collagen XVIII. It has also a broad research profile in the field of medical research and further investigation can show promising therapeutic effects for benefit of mankind.

Vascular endothelial growth factor (VEGF), transforming growth factor beta (TGFß), angiostatin, and endostatin are increased in radiotherapy-induced gastrointestinal toxicity.

PURPOSE: Radiotherapy-induced gut toxicity (RIGT) is a debilitating effect of radiotherapy for cancer, often resulting in significant diarrhea and pain. Previous studies have highlighted roles of the intestinal microvasculature and matrix metalloproteinases (MMPs) in the development of RIGT. We hypothesized vascular mediators would be significantly altered in a dark agouti (DA) rat model of RIGT. Additionally, we aimed to assess the effect of MMP-2 and -9 inhibition on the response of tumor-associated microvascular endothelial cells (TAMECs) to radiation. METHODS: DA rats were administered 2.5 Gy abdominal irradiation (3 times/week over 6 weeks). Vascular endothelial growth factor (VEGF), transforming growth factor beta (TGFß), von Willebrand factor (VWF), angiostatin, and endostatin expression was assessed at 3, 6, and 15 weeks. Additionally, DA rat mammary adenocarcinoma tumor-associated microvascular endothelial cells (TAMECs) were used to assess the effects of radiation (12 Gy) and the MMP inhibitor SB-3CT on MMP, VEGF, and TGFß expression, and cell viability. RESULTS: VEGF mRNA expression was significantly increased in the colon at week 15 (p = .0012), and TGFß mRNA expression was significantly increased in both the jejunum and colon at week 3 (p = .0280 and p = .0310, respectively). Endostatin immunostaining was significantly increased at week 3 (p = .0046), and angiostatin at 3 and 6 weeks (p = .0022 and p = .0135, respectively). MMP-2 and -9 mRNA and total protein levels were significantly increased following irradiation of TAMECs. Although this increase was significantly attenuated by SB-3CT, it did not significantly alter endothelial cell viability or VEGF and TGFß mRNA expression. CONCLUSIONS: Findings of this study support the involvement of VEGF, TGFß, angiostatin, endostatin, and MMP-2 in the pathobiology of RIGT. However, the relationship between these mediators is complex and needs further investigation to improve understanding of their therapeutic potential in RIGT.

Endostatin a Potential Biomarker for Heart Failure with Preserved Ejection Fraction / Endostatina é um Potencial Biomarcador para a Insuficiência Cardíaca com Fração de Ejeção Preservada

Abstract Background: Endostatin is a circulating endogenous angiogenesis inhibitor preventing neovascularization. Previous studies demonstrated the prognostic value of Endostatin among patients with heart failure with reduced ejection fraction (HFrEF). However, the role of Endostatin among patients with heart failure with preserved ejection fraction (HFpEF) remains unclear. Objective: This study aimed to investigate the association between serum Endostatin levels, natriuretic peptide levels and the severity of left ventricular diastolic dysfunction and the diagnosis of HFpEF. Methods: Endostatin serum concentrations were measured in 301 patients comprising 77 HFpEF patients, 169 patients with asymptomatic left ventricular diastolic dysfunction (ALVDD), and 55 controls with normal cardiac function. Results: Endostatin serum levels were significantly elevated in patients with HFpEF (median/interquartile range 179.0 [159-220]) and ALVDD (163.8 [145.4-191.3]) compared to controls (149.1 [130.6-176.9]), p < 0.001 and p = 0.004, respectively) and significant correlated with N-terminal pro B-type natriuretic peptide (NT-proBNP). Conclusions: This hypothesis-generating pilot study gives first evidence that Endostatin correlates with the severity of diastolic dysfunction and may become a novel biomarker for HFpEF. We hypothesize a rise in Endostatin levels may reflect inhibition of adaptive angiogenesis and adverse cardiac remodeling.

Resumo Fundamentos: A Endostatina é um inibidor circulante endógeno da angiogênese que previne a neovascularização. Estudos anteriores demonstraram o valor prognóstico da Endostatina em pacientes com insuficiência cardíaca com fracção de ejeção reduzida (ICFEr). No entanto, o papel da Endostatina entre os pacientes com insuficiência cardíaca com fração de ejeção preservada (ICFEp) permanece incerto. Objetivo: Investigar a associação entre os níveis séricos de Endostatina, níveis de peptídeos natriuréticos e a gravidade de disfunção ventricular esquerda e diastólica e o diagnóstico de ICFEp. Métodos: Mediu-se a concentração sérica de Endostatina em 301 pacientes, compreendendo 77 pacientes com ICFEp, 169 pacientes com disfunção ventricular esquerda assintomática diastólica (DVEAD) e 55 controles com a função cardíaca normal. Resultados: Os níveis de Endostatina no soro foram significativamente elevados em pacientes com ICFEp (mediana / intervalo interquartil 179,0 [159-220]) e DVEAD (163,8 [145,4-191,3]) em comparação com os controles (149,1 [130,6-176,9]), p < 0,001 e p = 0,004, respectivamente) e correlação significativa com o terminal do pro-peptídeo natriurético tipo B (NT-proBNP). Conclusões: Este estudo piloto gerador de hipótese fornece a primeira evidência de que a Endostatina se correlaciona com a gravidade da disfunção diastólica e pode tornar-se um novo biomarcador para ICFEp. Nossa hipótese é de que um aumento nos níveis de Endostatina pode refletir inibição da angiogênese adaptativa e remodelação cardíaca adversa.

Endostatin a Potential Biomarker for Heart Failure with Preserved Ejection Fraction.

BACKGROUND: Endostatin is a circulating endogenous angiogenesis inhibitor preventing neovascularization. Previous studies demonstrated the prognostic value of Endostatin among patients with heart failure with reduced ejection fraction (HFrEF). However, the role of Endostatin among patients with heart failure with preserved ejection fraction (HFpEF) remains unclear. OBJECTIVE: This study aimed to investigate the association between serum Endostatin levels, natriuretic peptide levels and the severity of left ventricular diastolic dysfunction and the diagnosis of HFpEF. METHODS: Endostatin serum concentrations were measured in 301 patients comprising 77 HFpEF patients, 169 patients with asymptomatic left ventricular diastolic dysfunction (ALVDD), and 55 controls with normal cardiac function. RESULTS: Endostatin serum levels were significantly elevated in patients with HFpEF (median/interquartile range 179.0 [159-220]) and ALVDD (163.8 [145.4-191.3]) compared to controls (149.1 [130.6-176.9]), p < 0.001 and p = 0.004, respectively) and significant correlated with N-terminal pro B-type natriuretic peptide (NT-proBNP). CONCLUSIONS: This hypothesis-generating pilot study gives first evidence that Endostatin correlates with the severity of diastolic dysfunction and may become a novel biomarker for HFpEF. We hypothesize a rise in Endostatin levels may reflect inhibition of adaptive angiogenesis and adverse cardiac remodeling.

Endostatin's emerging roles in angiogenesis, lymphangiogenesis, disease, and clinical applications.

BACKGROUND: Angiogenesis is the process of neovascularization from pre-existing vasculature and is involved in various physiological and pathological processes. Inhibitors of angiogenesis, administered either as individual drugs or in combination with other chemotherapy, have been shown to benefit patients with various cancers. Endostatin, a 20-kDa C-terminal fragment of type XVIII collagen, is one of the most potent inhibitors of angiogenesis. SCOPE OF REVIEW: We discuss the biology behind endostatin in the context of its endogenous production, the various receptors to which it binds, and the mechanisms by which it acts. We focus on its inhibitory role in angiogenesis, lymphangiogenesis, and cancer metastasis. We also present emerging clinical applications for endostatin and its potential as a therapeutic agent in the form a short peptide. MAJOR CONCLUSIONS: The delicate balance between pro- and anti-angiogenic factors can be modulated to result in physiological wound healing or pathological tumor metastasis. Research in the last decade has emphasized an emerging clinical potential for endostatin as a biomarker and as a therapeutic short peptide. Moreover, elevated or depressed endostatin levels in diseased states may help explain the pathophysiological mechanisms of the particular disease. GENERAL SIGNIFICANCE: Endostatin was once sought after as the 'be all and end all' for cancer treatment; however, research throughout the last decade has made it apparent that endostatin's effects are complex and involve multiple mechanisms. A better understanding of newly discovered mechanisms and clinical applications still has the potential to lead to future advances in the use of endostatin in the clinic.

Expression of a disintegrin and metalloprotease 8 and endostatin in human osteosarcoma: implication in tumor progression and prognosis.

BACKGROUND: A disintegrin and metalloprotease 8 (ADAM8) is a trans-membrane protein, which is involved in cell adhesion, signaling and migration as well as the proteolytic cleavage of various substrates. Endostatin is a potent inhibitor of angiogenesis. ADAM8 and Endostatin have been associated with multiple malignancies. However, their role in osteosarcoma is not fully elucidated. AIM: To determine the expression of ADAM8 and endostatin in osteosarcoma and to study their correlation with different clinicopathological parameters and patients' outcomes. MATERIAL AND METHODS: ADAM8 and endostatin expression were immunohistochemically evaluated in 61 primary osteosarcomas and 11 pulmonary metastatic osteosarcoma lesions. RESULTS: Among 61 primary osteosarcomas, ADAM8 was detected in 52 tumors (85.2%) and highly expressed in 33 cases (54.1%). Positive endostatin expression was found in 28 tumors (45.9%). Higher ADAM8 and decreased endostatin expression rates in metastatic lesions compared to primary osteosarcoma were found but these differences were not statistically significant (p=0.086 & 0.558 respectively). High ADAM8 expression score and positive endostatin expression were significantly correlated with tumor size, stage and distant metastasis (p<0.05). Survival analysis showed that high ADAM8 expression was associated with poor overall survival (OS) (p=0.0002). Multivariate analysis revealed that ADAM8 expression level was an independent prognostic parameter for the OS (p=0.017). CONCLUSION: Our data suggest that ADAM8 and endostatin play a role in osteosarcoma progression. High ADAM8 expression serves as a reliable marker for poor prognosis in osteosarcoma patients.

Low-voltage-activated T-type Ca2+ channel inhibitors as new tools in the treatment of glioblastoma: the role of endostatin.

Ca(2+) plays a key role in intracellular signaling and controls various cellular processes such as proliferation, differentiation, cell growth, death, and apoptosis. Aberrant changes in intracellular Ca(2+) levels can promote undesired cell proliferation and migration and are therefore associated with certain tumor types. Many research groups have suggested a potential role for voltage-gated Ca(2+) channels in the regulation of tumor growth and progression, particularly T-type channels due to their unique biophysical properties. T-type channels are expressed in normal tissues throughout the body and in different types of tumors such as breast carcinoma, retinoblastoma, neuroblastoma, and glioma. It has been demonstrated that increased functional expression of the α1 subunit of T-type channels plays a role in the abnormal proliferation of glioblastoma cells. As such, siRNA-mediated knockdown of the expression of the α1 subunit of T-type channels decreases the proliferation of these cells. Moreover, pharmacological blockade of T-type channels significantly decreases tumor growth. In this review, we focus on the use of T-type channel blockers for the potential treatment of cancers, particularly highly proliferative tumors such as glioblastoma. We conclude that T-type channel blockers such as endostatin can serve as a potential therapeutic tool for tumors whose proliferation depends on increased T-type channel expression.

Dysregulation of angiogenic homeostasis in systemic sclerosis.

BACKGROUND: Systemic sclerosis (SSc) is a connective tissue disorder characterized by tissue hypoxia and excessive fibrosis of skin and internal organs. OBJECTIVE: To evaluate the possible role of angiogenesis imbalance in the pathogenesis of SSc. SUBJECTS AND METHODS: Twenty-five SSc patients and 20 age- and sex-matched healthy controls were included. Assay of serum vascular endothelial growth factor (VEGF) and endostatin was done for all patients and controls using enzyme-linked immunosorbent assay. Patients were subjected to modified Rodnan skin score (mRss), pulmonary function tests (PFTS) and skin biopsies for histopathological skin thickness score assessment. RESULTS: There was significant increase in the mean levels of serum VEGF and endostatin in SSc patients compared to controls (t = 4.07, P < 0.001). Mean values of serum endostatin was significantly increased in late compared to early stages of disease (t = 6.65, P < 0.01). A significant positive correlation was found between serum levels of endostatin, mRss and histopathological skin thickness score (r = 0.99, 0.94, respectively, P < 0.01). SSc patients with ischemic manifestations had significantly higher levels of serum endostatin compared to those without ischemic manifestations (t = 6.27, P < 0.001). SSc patients with restricted PFTS had significantly higher levels of serum endostatin compared to those without pulmonary manifestations (t = 4.3, P < 0.001). CONCLUSION: Angiogenic inhibitor (endostatin) is induced and outweighs angiogenic inducer (VEGF) in late stages of SSc. Increased serum endostatin is associated with skin sclerosis severity and pulmonary fibrosis and favors SSc disease progression.

Generation of antitumor peptides by connection of matrix metalloproteinase-9 peptide inhibitor to an endostatin fragment.

Previous applications of matrix metalloproteinase (MMP) inhibitors in cancer treatment have resulted in disappointing outcomes. Therefore, it is necessary to develop more active or better targeted MMP inhibitors. In this study, Inhibitor2, a heptapeptide MMP inhibitor, was connected to the N-terminus or C-terminus of ES-2, an 11-amino-acid antiangiogenic peptide, and two designed peptides, P2 and P4, were generated. P2 inhibited MMP-2, MMP-8, MMP-9, and tumor necrosis factor-α converting enzyme (TACE) activity with IC50 values of 1.40, 0.35, 1.36, and 1.95 µmol/l, whereas those for P4 were 19, 20, 18, and 18 µmol/l. P2 showed a higher affinity with integrin α5ß1 in a human umbilical vein endothelial cell (HUVEC) adhesion assay than P4. In the HUVEC migration assay, P2 showed a better inhibitory effect on HUVEC migration than P4 and Inhibitor2 and the inhibitory ratio at 2 µg/ml was 77%. In a chorioallantoic membrane assay, at a concentration of 3.28 µg/ml, P2 and P4 showed 69.8 and 56.8% inhibition of formation of new blood vessels on the embryo membrane. Furthermore, P2 significantly inhibited B16F10 growth in a syngeneic mouse model with an inhibition ratio of 57.92% by tumor weight at a dose of 20 mg/kg/day, whereas P4 and Inhibitor2 exerted no such in-vivo effect. The antiangiogenic effect of P2 was confirmed by CD31 staining of the tumor tissue sections. The Inhibitor2 part of P2 may function both as an MMP inhibitor and as a targeting motif. These studies represented an example of how to better apply the potent and peptidomimetic MMP inhibitors in cancer treatment.

Role of endostatin in fibroproliferative disorders.-as a candidate for anti-fibrosis therapy-.

There are no effective treatments for fibrosis, an out-of-control wound-healing process in which excessive deposition of extracellular matrix (ECM) such as collagen, resulting in significant morbidity and mortality. Endostatin is a natural proteolytic fragment of collagen XVIII, which is known to possess potent antiangiogenic activity. Many clinical trials of endostatin have been conducted for anti-cancer therapy. In addition to antiangiogenic effects, recent studies have revealed that endostatin may suppress aberrant tissue remodeling and scarring. Neutralization of endogenous endostatin in rat myocardial infarction (MI) model worsened the outcomes of MI, indicating that endostatin may have protective role against left ventricular remodeling and heart failure after MI. Recently, we also reported inhibitory effects of peptides derived from endostatin on fibrosis. A peptide derived from the C-terminus of endostatin suppressed ECM production in fibroblasts in the presence of transforming growth factor-ß (TGF-ß), prevented TGF-ß-induced dermal fibrosis ex vivo in human skin, and ameliorated skin and pulmonary fibrosis induced by bleomycin in vivo. The antifibrotic capacity was accompanied by reduced cell apoptosis and lower levels of lysyl oxidase and early growth response gene-1. Endostation may have the therapeutic potential for inhibiting fibrosis.

Endogenous angiogenesis inhibitors prevent adaptive capillary growth in left ventricular pressure overload hypertrophy.

BACKGROUND: In left ventricular (LV) pressure-overload hypertrophy, lack of adaptive capillary growth contributes to progression to failure. Remodeling of the hypertrophied myocardium requires proteolysis of the extracellular matrix (ECM) carried out by matrix metalloproteinases (MMPs). MMPs, specifically MMP-9, are known to cleave ECM components to generate angiogenesis inhibitors (angiostatin, endostatin, tumstatin). We hypothesize that MMP-9 releases antiangiogenic factors during compensated and decompensated hypertrophy, which results in lack of adaptive capillary growth. METHODS: Newborn rabbits underwent aortic banding. Myocardial tissue from age-matched and banded animals at compensated (4 weeks) and decompensated hypertrophy (7 weeks), as identified by serial echocardiography, was analyzed by immunoblotting for angiostatin, endostatin, and tumstatin. MMP-9 activity was determined by zymography. A cell-permeable, potent, selective MMP-9 inhibitor was administered intrapericardially to animals with hypertrophied hearts and tissue was analyzed. RESULTS: MMP-9 is activated in hypertrophied myocardium versus in control hearts (22 ± 2 versus 16 ± 1; p = 0.04), which results in significantly increased levels of angiostatin (115 ± 10 versus 86 ± 7; p = 0.02), endostatin (33 ± 1 versus 28 ± 1; p = 0.006), and tumstatin (35 ± 6 versus 17 ± 4; p = 0.04). Zymography confirms inhibition of MMP-9 (hypertrophy + MMP-9 inhibitor, 14 ± 0.6 versus hypertrophy + vehicle, 17 ± 1; p = 0.01) and angiostatin, endostatin, and tumstatin are down-regulated, accompanied by up-regulation of capillary density (hypertrophy + MMP-9 inhibitor, 2.99 ± 0.07 versus hypertrophy + vehicle, 2.7 ± 0.05; p = 0.002). CONCLUSIONS: Up-regulation of angiogenesis inhibitors prevents adaptive capillary growth in pressure-overload hypertrophied myocardium. Therapeutic interventions aimed at inhibition of angiogenesis inhibitors are useful in maintaining capillary density and thereby preventing heart failure.

Early-onset coronary artery disease after pediatric kidney transplantation: implicating the angiogenesis inhibitor, endostatin.

Pediatric kidney transplant recipients have a higher rate of coronary artery disease (CAD) as adults. The angiogenesis inhibitor, endostatin, has been implicated in the development of atherosclerosis. Endostatin levels will vary between adult patients who received a kidney transplant as a child. We conducted a study in young adult patients who had undergone pediatric kidney (n = 12) or liver transplantation (n = 8). Coronary arterial calcification was measured using electron beam CT. Values were compared with age-matched control subjects from an epidemiologic database. Serum endostatin levels were measured using enzyme-linked immunosorbent assay. Risk factors for atherosclerosis were assessed. Kidney transplant recipients had a higher rate of CAD compared with liver transplant recipients (33 vs 0%, P = 0.03). Mean (± standard error of mean) serum endostatin levels were higher in kidney transplant recipients compared with liver transplant recipients (26 ± 7 vs 14 ± 3 ng/mL, P = 0.04) and control subjects (26 ± 7 vs 11 ± 1 ng/mL, P = 0.01). Pediatric kidney transplantation is associated with a higher rate of adult-onset CAD compared with liver transplantation. Endostatin levels were greater in kidney transplant recipients compared with liver transplant recipients and healthy control subjects. Endostatin may play a role in the development of atherosclerosis after kidney transplantation and may serve as a biomarker for atherosclerotic disease.

The multiple functions of collagen XVIII in development and disease.

Collagen XVIII is a heparan sulphate proteoglycan which is expressed ubiquitously in different basement membranes throughout the body. Its C-terminal fragment, endostatin, has been found to inhibit angiogenesis and tumor growth by restricting endothelial proliferation and migration and inducing apoptosis of endothelial cells. Collagen XVIII has three variants, of which the shortest one is found in most vascular and epithelial BM structures, whereas the longer variants are found especially in the liver. The longest or frizzled variant has a cysteine-rich domain in its N-terminus that has been shown to inhibit Wnt signaling in vitro. The presence of collagen XVIII homologues in organisms such as C. elegans, Xenopus laevis, zebrafish and chick suggests a fundamental role for this BM collagen. Mutations in the collagen XVIII gene lead to the Knobloch syndrome, which is characterized by high myopia, vitreoretinal degeneration with retinal detachment, macular abnormalities and occipital encephalocele. Mice lacking collagen XVIII also show several ocular abnormalities. This suggests that in physiological conditions collagen XVIII is mostly needed for the proper development of the eye. Moreover, it appears to be needed for the structural stability of basement membranes in several other organs, and increasing evidence shows its importance for other organs in non-physiological situations such as atherosclerosis, glomerulonephritis or other type of tissue damage. This review focuses on clarifying the roles of collagen XVIII and its variants and domains in various physiological and pathological conditions.

Role of gelatinases (matrix metalloproteinases 2 and 9), vascular endothelial growth factor and endostatin on clinicopathological behaviour of rectal cancer.

AIM: The aim of this study was to evaluate the role of matrix metalloproteinases (MMPs), their tissue inhibitors [tissue inhibitors of metalloproteinases (TIMPs)] and activators [membrane-type MMPs (MT1-MMPs)], vascular endothelial growth factor (VEGF) and endostatin on clinicopathological variables and prognosis in patients with rectal cancer. METHOD: Paired samples of tumour tissue and normal tissue were obtained from patients with rectal cancer who underwent curative surgery (n = 34). Gelatin zymography for MMP-2 and MMP-9, an activity assay for MT1-MMP and enzyme-linked immunoassays for TIMP-2, VEGF and endostatin were performed using extracts from the paired tissue samples. RESULTS: Active MMP-9 showed statistically significant relationships with metastatic disease and perineural invasion (P = 0.002 and P = 0.042). A significant relationship was observed between the levels of tumoral pro-MMP-2 and pro-MMP-9 and the presence of lymph node metastasis (P = 0.012 and P = 0.021, respectively). Tumoral TIMP-2 levels showed a significant relationship with tumour recurrence (P = 0.011). A significant relationship was also observed between tumour VEGF levels and the presence of perineural invasion (P = 0.044), and VEGF levels were correlated with the size of the tumour (P = 0.009, r = 0.454). CONCLUSION: These results might contribute to further investigation of a possible prognostic significance in rectal cancer.

Suppression of bladder cancer growth in mice by adeno-associated virus vector-mediated endostatin expression.

Novel treatment strategies such as gene therapy are warranted in view of the failure of current treatment approaches to cure a high percentage of patients with advanced bladder cancers. Testing of the hypothesis that blocking the angiogenic switch may keep tumour growth in check has been facilitated by the discovery of endogenous inhibitors of angiogenesis and has also added another research dimension to the field of cancer gene therapy. Consequently, the concept of targeting the tumour vasculature with anti-angiogenic agents has emerged as an attractive new strategy in the treatment of cancer. Targeted biological therapies that selectively interfere with tumour angiogenesis could improve survival among patients with bladder cancer. Endostatin is a tumour-derived angiogenesis inhibitor and is the first endogenous inhibitor of angiogenesis to be indentified in a matrix protein. Gene therapy represents an attractive approach to treat cancers and other chronic diseases. The development of an effective delivery system is absolutely critical to the usefulness and safety of gene therapy. At present, the adeno-associated virus (AAV) vector has the most promising potential in view of its non-pathogenicity, wide tropisms and long-term transgene expression in vivo. Gene therapy studies using different serotypes of recombinant AAV (rAAV) as delivery vehicles have proved rAAVs to be an effective modality of cancer gene therapy. In the present study, an IgG fragment was inserted at the start of the sequence coding for endostatin with the aim of enabling continuous secretion of endostatin the serum. We also investigated the suppression effect of AAV-mediated endostatin expression on endothelial cells and in mice xenograft models of bladder cancer. Our data demonstrates that rAAV-endostatin controlled tumour cell growth and achieves strong anti-tumour efficacy in vivo.

Role of anti-angiogenic factor endostatin in the pathogenesis of experimental ulcerative colitis.

AIMS: Vascular endothelial growth factor (VEGF) and pathologic angiogenesis have been demonstrated to play a pathogenic role in the development and progression of inflammatory bowel disease. Thus, we hypothesized that the potent anti-angiogenic factor endostatin might play a beneficial role in experimental ulcerative colitis (UC). MAIN METHODS: We used three animal models of UC: (1) induced by 6% iodoacetamide (IA) in rats, or (2) by 3% dextran sulfate sodium (DSS) in matrix metalloproteinase-9 (MMP-9) knockout (KO) and wild-type mice, and (3) interleukin-10 (IL-10) KO mice. Groups of MMP-9 KO mice with DSS-induced UC were treated with endostatin or water for 5days. KEY FINDINGS: We found concomitant upregulation of VEGF, PDGF, MMP-9 and endostatin in both rat and mouse models of UC. A positive correlation between the levels of endostatin or VEGF and the sizes of colonic lesions was seen in IA-induced UC. The levels and activities of MMP-9 were also significantly increased during UC induced by IA and IL-10 KO. Deletion of MMP-9 decreased the levels of endostatin in both water- and DSS-treated MMP-9 KO mice. Treatment with endostatin significantly improved DSS-induced UC in MMP-9 KO mice. SIGNIFICANCE: 1) Concomitantly increased endostatin is a defensive response to the increased VEGF in UC, 2) MMP-9 is a key enzyme to generate endostatin which may modulate the balance between VEGF and endostatin during experimental UC, and 3) endostatin treatment plays a beneficial role in UC. Thus, anti-angiogenesis seems to be a new therapeutic option for UC.

Lack of collagen XVIII/endostatin exacerbates immune-mediated glomerulonephritis.

Collagen XVIII is a component of the highly specialized extracellular matrix associated with basement membranes of epithelia and endothelia. In the normal kidney, collagen XVIII is distributed throughout glomerular and tubular basement membranes, mesangial matrix, and Bowman's capsule. Proteolytic cleavage within its C-terminal domain releases the fragment endostatin, which has antiangiogenic properties. Because damage to the glomerular basement membrane (GBM) accompanies immune-mediated renal injury, we investigated the role of collagen XVIII/endostatin in this disorder. We induced anti-GBM glomerulonephritis in collagen XVIII alpha1-null and wild-type mice and compared the resulting matrix accumulation, inflammation, and capillary rarefaction. Anti-GBM disease upregulated collagen XVIII/endostatin expression within the GBM and Bowman's capsule of wild-type mice. Collagen XVIII/endostatin-deficient mice developed more severe glomerular and tubulointerstitial injury than wild-type mice. Collagen XVIII/endostatin deficiency altered matrix remodeling, enhanced the inflammatory response, and promoted capillary rarefaction and vascular endothelial cell damage, but did not affect endothelial proliferation. Supplementing collagen XVIII-deficient mice with exogenous endostatin did not affect the progression of anti-GBM disease. Taken together, these results suggest that collagen XVIII/endostatin preserves the integrity of the extracellular matrix and capillaries in the kidney, protecting against progressive glomerulonephritis.

Short-term induction of thrombocytopenia delays periodontal healing in rats with periodontal disease: participation of endostatin and vascular endothelial growth factor.

BACKGROUND AND OBJECTIVE: Platelets contain factors, including VEGF and endostatin, that can modulate the healing process. We evaluated the effects of severe thrombocytopenia on periodontal healing in rats and determined the contribution of VEGF and endostatin to the healing process. MATERIAL AND METHODS: Rats were distributed into three test groups and two control groups. Cotton ligatures were placed at the gingival margin level of the lower first molar in the test groups. Sham-operated rats and rats in one of the periodontitis groups were killed 15 days later. Rats in the remaining two periodontitis groups had the ligatures removed in order to study the spontaneous recovery from the periodontal disease 15 days later, and these rats were treated with rabbit antiplatelet serum, in order to induce thrombocytopenia, or normal rabbit serum. An additional group without ligatures received antiplatet serum in the same period. RESULTS: After ligature removal, rats treated with normal rabbit serum showed reduced myeloperoxidase activity, decreased alveolar bone loss and increased numbers of blood vessels. Thrombocytopenia caused a delay in alveolar bone regeneration, a decrease in the number of vessels and a modest decrease in myeloperoxidase activity. In the rats with periodontitis, serum endostatin concentrations were slightly decreased and serum VEGF remained unchanged compared with sham-operated animals. After ligature removal, a significant VEGF increase and endostatin decrease were observed in the rats treated with normal rabbit serum. Thrombocytopenia led to a dramatic fall in both VEGF and endostatin concentrations. CONCLUSION: Thrombocytopenia leads to a delay of periodontal healing in the situation of experimental periodontitis, which might be mediated in part by a decrease in the serum concentration of VEGF and endostatin derived from the platelets. However, other factors derived from the platelets may also have contributed to a delay of periodontal healing in the rats with thrombocytopenia.