Acute cardiac tamponade after Endostar treatment of non-small cell lung cancer: A case report

RATIONALE

Recombinant human endostatin (Endostar) is extensively utilized in China for the clinical management of patients with driver gene-negative non-small cell lung cancer (NSCLC) at stage TNM IV. This report describes the case of a lung cancer patient treated exclusively with Endostar maintenance therapy, who experienced a rapid deterioration in respiratory function.

PATIENT CONCERNS

The case involved a patient with a pathologically confirmed squamous cell carcinoma of the left lung, treated in our department. Following 1 month of albumin-bound paclitaxel chemotherapy and localized radiotherapy for the left lung lesion, the patient initiated treatment with a single agent, Endostar 30mg, on October 19, 2021. The medication was administered via intravenous infusion over a 7 days.

DIAGNOSIS

On October 23, 2021, the patient exhibited symptoms of chest constriction, discomfort, coughing, and sputum production. By October 28, the patient presented with pronounced dyspnea and respiratory distress. An emergency CT scan detected pericardial tamponade and significant deviations in several blood parameters from pretreatment values.

INTERVENTIONS

Percardial puncture and catheter drainage were recommended as therapeutic intervention.

OUTCOMES

Considering the patient advanced age, the patient and their family opted to refuse this medical procedure, leading to the patient unfortunate demise on November 2, 2021.

LESSONS

Medical professionals should remain vigilant for the potential, albeit rare, risk of Endostar inducing acute pericardial tamponade, a severe and potentially fatal complication.

Overexpression of VEGFα as a biomarker of endothelial dysfunction in aortic tissue of α-GAL-Tg/KO mice and its upregulation in the serum of patients with Fabry's disease

Introduction

Fabry's disease is an X-linked lysosomal storage disorder caused by reduced activity of α-galactosidase A (GAL), leading to premature death on account of renal, cardiac, and vascular organ failure. Accumulation of the GAL substrate globotriaosylceramide (Gb3) in endothelial and smooth muscle cells is associated with early vascular cell damage, suggesting endothelial dysfunction as a driver of cardiorenal organ failure. Here, we studied the vascular expression of the key angiogenic factors, VEGFα and its antagonist angiostatin, in Fabry α-GAL-Tg/KO mice and determined circulating VEGFα and angiostatin serum levels in patients with Fabry's disease and healthy controls.

Methods

Cryopreserved aortic vessels from six α-GAL-Tg/KO and six wild-type (WT) mice were obtained and VEGFα and angiostatin levels were determined by performing Western blot analysis. VEGFα expression was visualized by an immunohistochemical staining of paraffin aortic rings. In addition, VEGFα and angiostatin serum levels were measured by using an enzyme-linked immunosorbent assay in 48 patients with genetically verified Fabry's disease (50% male) and 22 healthy controls and correlated with disease severity markers such as lyso-Gb3, albuminuria, NTproBNP, high-sensitive troponin T (hsTNT), and myocardial wall thickness.

Results

It was found that there was a significant increase in VEGFα protein expression (1.66 ± 0.35 vs. 0.62 ± 0.16, p = 0.0009) and a decrease in angiostatin expression (0.024 ± 0.007 vs. 0.053 ± 0.02, p = 0.038) in aortic lysates from α-GAL-Tg/KO compared with that from WT mice. Immunohistochemical staining revealed an adventitial VEGFα signal in α-GAL-Tg/KO mice, whereas no VEGFα signal could be detected in WT mice aortas. No differences in aortic angiostatin expression between α-GAL-Tg/KO- and WT mice could be visualized. The serum levels of VEGFα were significantly upregulated in patients with Fabry's disease compared with that in healthy controls (708.5 ± 426.3 vs. 458.5 ± 181.5 pg/ml, p = 0.048) and positively associated with albuminuria (r = 0.82, p < 0.0001) and elevated NTproBNP (r = 0.87, p < 0.0001) and hsTNT values (r = 0.41, p = 0.048) in male patients with Fabry's disease. For angiostatin, no significant difference was found between patients with Fabry's disease and healthy controls (747.6 ± 390.3 vs. 858.8 ± 599.3 pg/ml).

Discussion

In conclusion, an overexpression of VEGFα and downregulation of its counter player angiostatin in aortic tissue of α-GAL-Tg/KO mice support the hypothesis of an underlying vasculopathy in Fabry's disease. Elevated VEGFα serum levels were also observed in patients with Fabry's disease and were positively associated with elevated markers of organ manifestation in males. These findings suggest that angiogenetic markers, such as VEGFα, may be potentially useful biomarkers for the detection of endothelial dysfunction in classical Fabry's disease.

Computational Multi-Scale Modeling of Drug Delivery into an Anti-Angiogenic Therapy-Treated Tumor

The present study develops a numerical model, which is the most complex one, in comparison to previous research to investigate drug delivery accompanied by the anti-angiogenesis effect. This paper simulates intravascular blood flow and interstitial fluid flow using a dynamic model. The model accounts for the non-Newtonian behavior of blood and incorporates the adaptation of the diameter of a heterogeneous microvascular network derived from modeling the evolution of endothelial cells toward a circular tumor sprouting from two-parent vessels, with and without imposing the inhibitory effect of angiostatin on a modified discrete angiogenesis model. The average solute exposure and its uniformity in solid tumors of different sizes are studied by numerically solving the convection-diffusion equation. Three different methodologies are considered for simulating anti-angiogenesis: modifying the capillary network, updating the transport properties, and considering both microvasculature and transport properties modifications. It is shown that anti-angiogenic therapy decreases drug wash-out in the periphery of the tumor. Results show the decisive role of microvascular structure, particularly its distribution, and interstitial transport properties modifications induced via vascular normalization on the quality of drug delivery, such that it is improved by 39% in uniformity by the second approach in R = 0.2 cm.

Phosphoglycerate kinase (PGK) 1 succinylation modulates epileptic seizures and the blood-brain barrier

Epilepsy is the most common chronic disorder in the nervous system, mainly characterized by recurrent, periodic, unpredictable seizures. Post-translational modifications (PTMs) are important protein functional regulators that regulate various physiological and pathological processes. It is significant for cell activity, stability, protein folding, and localization. Phosphoglycerate kinase (PGK) 1 has traditionally been studied as an important adenosine triphosphate (ATP)-generating enzyme of the glycolytic pathway. PGK1 catalyzes the reversible transfer of a phosphoryl group from 1, 3-bisphosphoglycerate (1, 3-BPG) to ADP, producing 3-phosphoglycerate (3-PG) and ATP. In addition to cell metabolism regulation, PGK1 is involved in multiple biological activities, including angiogenesis, autophagy, and DNA repair. However, the exact role of PGK1 succinylation in epilepsy has not been thoroughly investigated. The expression of PGK1 succinylation was analyzed by Immunoprecipitation. Western blots were used to assess the expression of PGK1, angiostatin, and vascular endothelial growth factor (VEGF) in a rat model of lithium-pilocarpine-induced acute epilepsy. Behavioral experiments were performed in a rat model of lithium-pilocarpine-induced acute epilepsy. ELISA method was used to measure the level of S100β in serum brain biomarkers' integrity of the blood-brain barrier. The expression of the succinylation of PGK1 was decreased in a rat model of lithium-pilocarpine-induced acute epilepsy compared with the normal rats in the hippocampus. Interestingly, the lysine 15 (K15), and the arginine (R) variants of lentivirus increased the susceptibility in a rat model of lithium-pilocarpine-induced acute epilepsy, and the K15 the glutamate (E) variants, had the opposite effect. In addition, the succinylation of PGK1 at K15 affected the expression of PGK1 succinylation but not the expression of PGK1total protein. Furthermore, the study found that the succinylation of PGK1 at K15 may affect the level of angiostatin and VEGF in the hippocampus, which also affects the level of S100β in serum. In conclusion, the mutation of the K15 site of PGK1 may alter the expression of the succinylation of PGK1 and then affect the integrity of the blood-brain barrier through the angiostatin / VEGF pathway altering the activity of epilepsy, which may be one of the new mechanisms of treatment strategies.

To what extent should the intestinal be resected proximally after radiotherapy: hint from a pathological view

Background

Neoadjuvant chemoradiotherapy (nCRT) is associated with post-operative anastomotic complications in rectal-cancer patients. Anastomosis involving at least one non-irradiated margin reportedly significantly reduces the risk of post-operative anastomotic complications in radiation enteritis. However, the exact scope of radiotherapy on the remaining sigmoid colon remains unknown.

Methods

We evaluated the radiation damage of proximally resected colorectal segments in 44 patients with rectal cancer, who received nCRT followed by conventional resection (nCRT-C, n = 21) or proximally extended resection (nCRT-E, n = 23). The segments from another 13 patients undergoing neoadjuvant chemotherapy (nCT) were used as control. We dissected these samples at a distance of 2 cm between the two adjacent sections. Radiation damage in proximally resected colorectal segments was evaluated using the radiation injury score (RIS) and the concentration and distribution patterns of angiostatin.

Results

Compared to those in the nCT group, the nCRT group showed higher RIS, levels of angiostatin, and proportion of diffuse pattern of angiostatin. With increasing distance from the tumor site, these parameters all gradually decreased; and the differences came to be not significant at the site that is over 20 cm from the tumor. The nCRT-E group showed lower RIS (median: 2 vs 4, P = 0.002) and a greater proportion of non-diffuse angiostatin (87% vs 55%, P = 0.039) at the proximal margins compared with the nCRT-C group.

Conclusions

The severity of the radiation damage of the proximal colon is inversely proportional to the proximal-resection margin length. Little damage was left on the proximal margin that was over 20 cm from the tumor. Removal of an initial length of ≥20 cm from the tumor may be beneficial for rectal-cancer patients after nCRT.

Effect of Diosmin Administration in Patients with Chronic Venous Disorders on Selected Factors Affecting Angiogenesis

Diosmin is a natural compound with a wide range of biological activity, e.g., it improves lymphatic drainage, supports microcirculation, and increases venous tone, and venous elasticity, hence, it is applied in the pharmacotherapy of chronic venous disorders (CVD). The aim of this study was to assess the correlation between diosmin administration (2 × 600 mg daily) in patients suffering from CVD and the levels of selected factors influencing angiogenesis, which are involved in CVD pathophysiology. Thirty-five CVD patients were examined. Levels of plasma tumor necrosis factor alpha (TNF alpha), vascular endothelial growth factor (VEGF-A and VEGF-C); angiostatin, interleukin 6 (IL-6), fibroblast growth factor 2 (FGF2); and plasminogen (PLG) were measured with an Elisa assay before and after three months of diosmin administration. The clinical symptoms of CVD were monitored using ultrasound images, echo Doppler assay, visual analogue scale (VAS), and measurement of the leg circumference. The average content of TNF alpha, VEGF-C, VEGF-A IL-6, and FGF2 decreased after the therapy with diosmin in a significant manner; with p < 0.001, p < 0.05, p < 0.05, p < 0.01, and p < 0.01, respectively, and a significant (p < 0.05) increase in the plasma angiostatin level after the three-month treatment was found. A significant (p < 0.05) decrease in edema and the average leg circumference of the patients was observed after the therapy. Diosmin influences the angiogenic and inflammatory mechanisms involved in the pathophysiology of edema presented in patients with a different class of CVD.

Angiostatin levels in diabetes mellitus patients receiving insulin treatment: associations with laboratory findings, comorbidities, and medications

Background/aim

The clinical effect of angiostatin in diabetes mellitus (DM) patients receiving insulin is a meaningful gap in the literature. In this study, we aimed to show the levels and the clinical significance of angiostatin in DM patients receiving insulin.

Materials and methods

This is a case-control study. Serum angiostatin levels were determined by ELISA. A total of 83 people consisting of healthy subjects (n = 36) and patients with a diagnosis of DM receiving insulin therapy (n = 47) were included in this study.

Results

The mean angiostatin levels of the DM group were significantly higher than those of the control group (86.0 ± 68.1 ng/mL and 58.0 ± 22.4 ng/mL, respectively; P = 0.011). Significantly lower angiostatin levels were determined in the DM patients receiving metformin with respect to those not receiving metformin (97.2 ± 74.4 ng/mL and 49.3 ± 7.0 ng/mL, respectively; P = 0.021). Significantly higher levels of angiostatin were observed among the DM patients using a beta-blocker (BB) than the DM patients not using a BB (115.5 ± 78.71 ng/mL and 73.44 ± 60.08 ng/mL, respectively; p = 0.029).

Conclusion

This is the first study evaluating and demonstrating the serum angiostatin levels in DM patients receiving insulin. Further studies are required to understand the effect of angiostatin in diabetics and the effect of medications on angiogenesis in these patients.

Serum angiostatin and endostatin levels in patients with granulomatosis with polyangiitis and immune complex small vessel vasculitis

Objectives

Inflammation has been revealed to be associated with angiogenesis. Granulomatosis with polyangiitis (GPA) and immune complex small vessel vasculitis (ICSVV) are forms of systemic vasculitides of different pathogenesis. GPA is a necrotizing granulomatosis and ICSVV is associated with inflammation of postcapillary venules induced by deposits of immune complexes. The aim of the study was to determine serum levels of angiostatin and endostatin, natural angiogenesis inhibitors, in patients with GPA and ICSVV as well as healthy individuals.

Material and methods

Two groups of patients with GPA (20 patients) and ICSVV (20 patients) as well as 20 controls were investigated. All patients were investigated before initiation of immunosuppressive therapy or administration of corticosteroids. Angiostatin and endostatin levels were assayed with the ELISA method.

Results

Enhanced serum levels of angiostatin and endostatin were found in patients with GPA but not in those suffering from ICSVV. In patients with GPA increased levels of angiogenesis inhibitors correlated with the disease activity. A correlation between angiostatin and endostatin levels was observed in all groups of investigated individuals.

Conclusions

It is suggested that formation of necrotizing granulation is associated with profound activation of angiogenesis and an increase in serum levels of inhibitors is a phenomenon occurring during blood vessel formation in the granulation tissue. The obtained results confirm involvement of angiogenesis in pathogenesis of at least some forms of vasculitides and suggest the need for continuation of investigations in this field.

Tumor angiogenesis and anti-angiogenic gene therapy for cancer

When Folkman first suggested a theory about the association between angiogenesis and tumor growth in 1971, the hypothesis of targeting angiogenesis to treat cancer was formed. Since then, various studies conducted across the world have additionally confirmed the theory of Folkman, and numerous efforts have been made to explore the possibilities of curing cancer by targeting angiogenesis. Among them, anti-angiogenic gene therapy has received attention due to its apparent advantages. Although specific problems remain prior to cancer being fully curable using anti-angiogenic gene therapy, several methods have been explored, and progress has been made in pre-clinical and clinical settings over previous decades. The present review aimed to provide up-to-date information concerning tumor angiogenesis and gene delivery systems in anti-angiogenic gene therapy, with a focus on recent developments in the study and application of the most commonly studied and newly identified anti-angiogenic candidates for anti-angiogenesis gene therapy, including interleukin-12, angiostatin, endostatin, tumstatin, anti-angiogenic metargidin peptide and endoglin silencing.

Circulating angiostatin serum level in patients with systemic sclerosis

Introduction

Systemic sclerosis (SSc) is achronic connective tissue disease characterized by microangiopathy with inadequate angiogenesis. Angiostatin (AS) is a potent antiangiogenic factor specifically inhibiting proliferation and inducing apoptosis of vascular endothelial cells.

Aim

To evaluate the level of angiostatin in the serum of patients with SSc.

Material and methods

Serum levels of AS were measured in 20 SSc patients and 12 healthy controls.

Results

A statistically significant difference in the serum levels of AS in SSc patients was observed compared to the control group (636.51 vs. 869.20 ng/ml; p = 0.012). Significant correlations between limited and disseminated SSc (lSSc/dSSc) were not found, however, a difference between lSSc and the control group was demonstrated (620.00 vs. 869.20 ng/ml; p = 0.011). The serum level of AS was not associated positively with organ changes caused by SSc. However, a statistically significant lower serum level of AS was observed in patients with SSc and no esophageal (p = 0.008) or pulmonary changes (p = 0.007) compared to the control group.

Conclusions

Our results reveal significant differences in AS level in SSc patients compared to the healthy controls, and suggest that a low level of AS may occur as a result of impaired angiogenesis.

A Hypothesis Concerning the Biphasic Dose-response of Tumors to Angiostatin and Endostatin

This manuscript proposes a hypothesis to explain the U-shaped dose-response observed for angiostatin and other high-molecular-weight drugs in various anti-cancer bio-assays. The dose-response curves for angiostatin and endostatin (measured as suppression of tumor growth) go through an optimum (i.e., minimum tumor growth) and then becomes less effective at higher doses. The literature suggests that at lower doses the primary action of these high-molecular-weight drugs is to counteract the angiogenic effects of vascular endothelial growth factor (VEGF). To do this, the drugs must pass out of the blood vessel and enter the extra-cellular matrix (ECM) where VEGF induces the growth and fusion of tip cells. Ironically, VEGF actually facilitates access of the drugs to the ECM by making the vascular endothelium leaky. At higher doses, the high-molecular-weight drugs seem to reverse VEGF-induced permeability of the endothelium. Thus, at high dose rates, it is hypothesized that the drugs are not able to enter the ECM and block the angiogenic effects of VEGF there. As a result, high doses of the drugs do not suppress vascularization of the tumor or tumor growth. Moreover, if the permeability of the vessels is suppressed, the VEGF released by the stroma is concentrated in the ECM where it amplifies the angiogenic activity around the tumor.

Overexpression of angiomotin in sinonasal inverted papilloma

BACKGROUND

Although inverted papilloma (IP) is one of the most common sinonasal tumors, its etiology and factors associated with tumor progression have not been fully determined. Generally, tumorigenesis or tumor growth requires angiogenesis to feed tumor cells. Angiomotin is a recently discovered protein that regulates migration and tubule formation in endothelial cells. It has been reported that angiomotin affects angiostatin (circulating inhibitor of angiogenesis), resulting in promotion of angiogenesis. Thus, we evaluated the expression and distribution of angiomotin in sinonasal IP, compared to normal control tissue.

METHODS

The study included 10 subjects with sinonasal IP and 5 normal controls. Ethmoid sinus mucosa obtained during reduction of blowout fractures was used as a normal control. Reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, immunohistochemistry, and Western blot analysis were used to assess the expression, intensity, and distribution of angiomotin in tissues.

RESULTS

Positive bands for angiomotin were seen in all specimens by RT-PCR. The expression level of angiomotin was significantly upregulated in IP tissues versus normal sinus mucosa by real-time PCR. Immunohistochemistry revealed positive reactions on endothelial cells of capillaries and small vessels within the tumor and normal tissues, but the positivity was significantly stronger in IP. Western blot analysis showed that expression levels of angiomotin were increased in IP compared to normal sinus mucosa.

CONCLUSION

Angiomotin, a novel protein in angiogenesis, was overexpressed in IP. Although it is not an etiological or initiating factor in tumor development, it seems to be associated with progression and growth of IP via promoting angiogenesis.

Impaired coronary collateral growth in the metabolic syndrome is in part mediated by matrix metalloproteinase 12-dependent production of endostatin and angiostatin

OBJECTIVE

We have previously shown that transient coronary artery occlusion stimulated coronary collateral growth (CCG) in healthy (Sprague Dawley) but not in metabolic syndrome (JCR:LA-cp [JCR] ) rats. Here, we sought to determine whether matrix metalloproteinases (MMPs) negatively regulate CCG in the metabolic syndrome via release of endostatin and angiostatin.

APPROACH AND RESULTS

Rats underwent transient, repetitive left anterior descending occlusion and resultant myocardial ischemia (RI) for 0 to 10 days. CCG was measured in the collateral-dependent and normal zones using microspheres, MMP activation by Western blot, and endostatin and angiostatin by ELISA on days 0, 3, 6, 9, or 10 of RI. Endostatin and angiostatin were increased in JCR but not in Sprague Dawley rats on days 6 and 9 of RI. Increased endostatin and angiostatin correlated with increased MMP12 (≈ 4-fold) activation in JCR but not in Sprague Dawley rats on days 6 and 9 of RI. Inhibition of MMP12 in JCR rats nearly completely blocked endostatin (≈ 85%) and angiostatin (≈ 90%) generation and significantly improved CCG (collateral-dependent zone flow was ≈ 66% of normal zone flow versus ≈ 12% for JCR RI).

CONCLUSIONS

Compromised CCG in the metabolic syndrome is, in large part, because of increased MMP12 activation and consequent increased generation of endostatin and angiostatin, which inhibits late-stage collateral remodeling.

Effect of angiostatin on 1,2-dimethylhydrazine-induced colon cancer in mice

Antiangiogenic therapy is supposed to be an attractive approach for antitumor treatment. Human plasminogen-derived angiostatin K1-3 is one of the most potent antiangiogenic agents known currently. However, it is unclear whether angiostatin has got protective effects on colon cancer. So we investigated the protective effects of angiostatin on 1,2-dimethylhydrazine (DMH)-induced colon cancer in mice. Thirty Balb/C male mice, weighing 25-30 g and 8 weeks of age, were used. Twenty of the mice were treated with DMH subcutaneously (20 mg/kg) once a week for 12 weeks. Six mice died during the DMH injection and surviving mice were divided into two groups (7 mice in DMH and 7 mice in DMH + angiostatin groups). In the angiostatin group, 6 weeks after the last DMH injection the animals were first treated with angiostatin (20 μg/mouse) intraperitoneally and then subcutaneously every 48 h (5 μg/mouse) throughout a period of 12 weeks. The animals were killed after 30 weeks for histopathological examination. When we look at the distribution of lesions in the colon, they mainly occurred in the distal colon. The incidence of mean colonic lesions in a tumor-bearing mouse was 9.85 ± 4.91 in those treated with DMH and 8.71 ± 3.49 in those treated with angiostatin. The incidence of colon tumors was not significantly affected by low dose of angiostatin, and we noticed that the number of lesions decreased by 12% in DMH + angiostatin group compared to the number of the lesions in DMH group, but this decrease was not statistically significant (p > 0.05). The administration period of angiostatin corresponds to the precancerous period and the reduction in the number of lesions could be important for the protective function of angiostatin in DMH + angiostain group. We assume that therapeutic effects of angiostatin are related to its doses, route of administration, frequency and administration period. In addition, we believe that combination of high doses of angiostatin with radiation, gene therapy or chemotherapy might be successful in proper tumor model.

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.

Inappropriate angiogenic response as a novel mechanism of duodenal ulceration and impaired healing

BACKGROUND

Despite recent advances and better understanding of the etiology and the pathogenesis of gastrointestinal ulcer diseases, e.g., duodenal ulcer, the molecular events leading to ulcer development, delayed healing, and recurrence remain poorly elucidated.

AIMS

After we found that duodenal ulcers did not heal despite increased levels of vascular endothelial growth factor (VEGF), we tested the hypothesis that an imbalance in angiogenic VEGF and anti-angiogenic endostatin and angiostatin might be important in the development and delayed healing of experimental duodenal ulcers.

METHODS

Levels of VEGF, endostatin, and angiostatin, and the expression and activity of related matrix metalloproteinases (MMP) 2 and 9 were measured in scrapings of rat proximal duodenal mucosa in the early and late stages of chemically induced duodenal ulceration. Furthermore, animals were treated with recombinant endostatin and MMP 2 inhibitor to test the relationship between MMP2 and endostatin and their involvement in healing of experimental duodenal ulcers.

RESULTS

A concurrent increase of duodenal VEGF, endostatin, and angiostatin was noted during duodenal ulceration. Endostatin treatment aggravated duodenal ulcer. Levels of MMP2, but not MMP9, were increased. Inhibition of MMP2 reduced levels of endostatin and angiostatin, and attenuated duodenal ulcers.

CONCLUSIONS

Increased levels of endostatin and angiostatin induced by MMP2 delayed healing of duodenal ulcers despite concurrently increased VEGF. Thus, an inappropriate angiogenic response or "angiogenic imbalance" may be an important new mechanism in ulcer development and impaired healing.

X-ray imaging of differential vascular density in MMP-9-/-, PAR-1-/+, hyperhomocysteinemic (CBS-/+) and diabetic (Ins2-/+) mice

Although protease activated receptor-1 (PAR-1) and matrix metalloproteinase-9 (MMP-9) play significant role in vascular remodelling in hyperhomocysteinemia (HHcy due to cystathionine beta synthase deficiency, CBS-/+) and diabetes, mechanism remains nebulous. We hypothesized that differential vascular density and remodelling in different vascular beds in HHcy and diabetes were responsible for an adaptive metabolic homeostasis during the pathogenesis. To test this hypothesis, vascular density in mice lacking PAR-1, MMP-9, CBS and Insulin-2 gene mutant (Ins2-/+, Akita) was measured and compared with wild type (WT, C57BL/6J) mice. The vascular density was detected by x-ray angiography using KODAK 4000 MM image station, using barium sulphate as contrasting agent. The % vascular density in the hearts of WT, CBS-/+ (HHcy), MMP-9-/-, PAR-1-/+ and Ins2-/+ (type-1 diabetes) was 100 ± 2.8, 85 ± 3.3, 90 ± 3.3, 95 ± 3.8 and 73 ± 1.7, respectively. The vascular density in CBS-/+ and Akita hearts decreased while it was increased in lungs of CBS-/+ and MMP-9-/-.There was decreased vascular density in liver and kidney of Akita mice. Vascular density in brain, kidney and mesentery was decreased in CBS-/+ mice. These findings support the notation that metabolic derangement in diabetes and HHcy causes the chronic decline and/or rarefaction in vascular density.

MMP-2/TIMP-2/TIMP-4 versus MMP-9/TIMP-3 in transition from compensatory hypertrophy and angiogenesis to decompensatory heart failure

Although matrix metalloproteinase (MMPs) and tissue inhibitor of metalloproteinase (TIMPs) play a vital role in tumour angiogenesis and TIMP-3 caused apoptosis, their role in cardiac angiogenesis is unknown. Interestingly, a disruption of co-ordinated cardiac hypertrophy and angiogenesis contributed to the transition to heart failure, however, the proteolytic and anti-angiogenic mechanisms of transition from compensatory hypertrophy to decompensatory heart failure were unclear. We hypothesized that after an aortic stenosis MMP-2 released angiogenic factors during compensatory hypertrophy and MMP-9/TIMP-3 released anti-angiogenic factors causing decompensatory heart failure. To verify this hypothesis, wild type (WT) mice were studied 3 and 8 weeks after aortic stenosis, created by banding the ascending aorta in WT and MMP-9-/- (MMP-9KO) mice. Cardiac function (echo, PV loops) was decreased at 8 weeks after stenosis. The levels of MMP-2 (western blot) increased at 3 weeks and returned to control level at 8 weeks, MMP-9 increased only at 8 weeks. TIMP-2 and -4 decreased at 3 and even more at 8 weeks. The angiogenic VEGF increased at 3 weeks and decreased at 8 weeks, the anti-angiogenic endostatin and angiostatin increased only at 8 weeks. CD-31 positive endothelial cells were more intensely labelled at 3 weeks than in sham operated or in 8 weeks banded mice. Vascularization, as estimated by x-ray angiography, was increased at 3 weeks and decreased at 8 weeks post-banding. Although the vast majority of studies were performed on control WT mice only, interestingly, MMP9-KO mice seemed to have increased vascular density 8 weeks after banding. These results suggested that there was increase in MMP-2, decrease in TIMP-2 and -4, increase in angiogenic factors and vascularization in compensatory hearts. However, in decompensatory hearts there was increase in MMP-9, TIMP-3, endostatin, angiostatin and vascular rarefaction.

Angiogenesis inhibitors found within the haemostasis pathway

Angiogenesis, the development of new blood vessels from the existing vasculature, and haemostasis, the coagulation cascade leading to formation of a clot, are among the most consistent host responses associated with cancer. Importantly, these two pathways interrelate, with blood coagulation and fibrinolysis influencing tumor angiogenesis directly, thereby contributing to tumor growth. Moreover, many endogenous inhibitors of angiogenesis are found within platelets or harboured as cryptic fragments of haemostatic proteins. In this review we outline ways in which angiogenesis is coordinated and regulated by haemostasis in human cancer. Then we detail the experimental and pre-clinical evidence for the ability of many of these endogenous proteins to inhibit tumor angiogenesis and thus their potential to be anti-cancer agents, with particular reference to any clinical trials.

An Inhibitor of the F1 subunit of ATP synthase (IF1) modulates the activity of angiostatin on the endothelial cell surface

Angiostatin binds to endothelial cell (EC) surface F(1)-F(0) ATP synthase, leading to inhibition of EC migration and proliferation during tumor angiogenesis. This has led to a search for angiostatin mimetics specific for this enzyme. A naturally occurring protein that binds to the F1 subunit of ATP synthase and blocks ATP hydrolysis in mitochondria is inhibitor of F1 (IF1). The present study explores the effect of IF1 on cell surface ATP synthase. IF1 protein bound to purified F(1) ATP synthase and inhibited F(1)-dependent ATP hydrolysis consistent with its reported activity in studies of mitochondria. Although exogenous IF1 did not inhibit ATP production on the surface of EC, it did conserve ATP on the cell surface, particularly at low extracellular pH. IF1 inhibited ATP hydrolysis but not ATP synthesis, in contrast to angiostatin, which inhibited both. In cell-based assays used to model angiogenesis in vitro, IF1 did not inhibit EC differentiation to form tubes and only slightly inhibited cell proliferation compared with angiostatin. From these data, we conclude that inhibition of ATP synthesis is necessary for an anti-angiogenic outcome in cell-based assays. We propose that IF1 is not an angiostatin mimetic, but it can serve a protective role for EC in the tumor microenvironment. This protection may be overridden in a concentration-dependent manner by angiostatin. In support of this hypothesis, we demonstrate that angiostatin blocks IF1 binding to ATP synthase and abolishes its ability to conserve ATP. These data suggest that there is a relationship between the binding sites of IF1 and angiostatin on ATP synthase and that IF1 could be employed to modulate angiogenesis.

Treatment of colorectal and hepatocellular carcinomas by adenoviral mediated gene transfer of endostatin and angiostatin-like molecule in mice

AIM AND METHOD

In this study, we explored the responsiveness of different tumour entities (colorectal carcinoma (CRC), hepatocellular carcinoma (HCC), and the murine Lewis lung carcinoma (LLC)) to angiostatic antitumour treatment with two recombinant adenoviral vectors encoding angiostatin-like molecule (AdK1-3) and endostatin (Adendo).

RESULTS

AdK1-3 and Adendo exerted inhibitory biological functions on endothelial cell proliferation, migration, and tube formation in vitro. AdK1-3 inhibited significantly endothelial cell infiltration in vascular endothelial growth factor embedded Matrigel plugs in mice whereas Adendo showed only minor effects. Both AdK1-3 and Adendo induced similar antitumour effects in the LLC tumour model in immune competent C57BL/6 mice but AdK1-3 had stronger inhibitory effects in athymic mice. Furthermore, AdK1-3 inhibited tumour growth in a murine CRC and human HCC model but was ineffective in a human CRC model. In contrast, Adendo did not reduce tumour progress in either of these tumour models although AdK1-3 and Adendo effectively reduced intratumoral microvessel density in LLC tumours.

CONCLUSION

Our data demonstrate that angiostatic gene therapy may form a feasible strategy for the treatment of established hepatocellular carcinomas and that in vivo antitumour efficacy of angiostatic proteins is tumour specific.

Effect of angiostatin on liver metastasis of pancreatic cancer in hamsters

The liver is the most common site of metastasis in pancreatic cancer, and there are no promising strategies to treat it. Angiostatin, a kringle-containing fragment of plasminogen, is a potent inhibitor of angiogenesis. The effect of angiostatin on liver metastasis in pancreatic cancer was investigated by using our established hamster model of liver metastasis. Pancreatic cancer cells (PGHAM-1, 1 x 10(6)) derived from N-nitrosobis(2-oxopropyl)amine (BOP)-induced pancreatic tumor in Syrian golden hamsters were transplanted into the spleen of female hamsters, and the animals were subcutaneously injected with angiostatin and saline. Subsequently, the macroscopic appearance of liver surface metastases was evaluated. In addition, histological sections of the liver metastases were analyzed for neovascularization, proliferation, and apoptosis on the basis of von Willebrand factor, argyrophilic nucleolar organizer region (Ag-NOR), and TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining, respectively. The results showed significant tumor growth retardation and inhibition of angiogenesis in metastatic liver tumors in response to treatment with angiostatin. Moreover, the metastases remained in a nearly dormant state due to a balance between apoptosis and proliferation of the tumor, with no detectable side effects. This is the first experimental trial of angiostatin on pancreatic cancer and liver metastasis. The results suggest that angiostatin therapy could be effective against liver metastases of pancreatic cancer.

Generation of angiostatin-like fragments from plasminogen by prostate-specific antigen

Angiostatin, a potent inhibitor of angiogenesis, tumour growth and metastasis, is a biologically active fragment of plasminogen, containing the kringle domains 1-4. It is generated from plasminogen by limited proteolysis. We show that prostate-specific antigen (PSA), a serine proteinase secreted by human prostate and human prostate cancer cells, is able to convert Lys-plasminogen to biologically active angiostatin-like fragments, containing kringles 1-4, by limited proteolysis of peptide bond Glu439-Ala440 in vitro. In an in vitro morphogenesis assay, the purified angiostatin-like fragments inhibited proliferation and tubular formation of human umbilical vein endothelial cells with the same efficacy as angiostatin. This finding might help to understand growth characteristics of prostate cancer, which usually has low microvessel density and slow proliferation.

Suppression of angiogenesis and tumor growth by the inhibitor K1-5 generated by plasmin-mediated proteolysis

Proteolytic enzymes are involved in generation of a number of endogenous angiogenesis inhibitors. Previously, we reported that angiostatin, a potent angiogenesis inhibitor, is a proteolytic fragment containing the first four kringle modules of plasminogen. In this report, we demonstrate that urokinase-activated plasmin can process plasminogen to release an angiogenesis inhibitor, K1-5 (protease-activated kringles 1-5). K1-5 inhibits endothelial-cell proliferation with a half-maximal concentration of approximately 50 pM. This inhibitory effect is endothelial-cell-specific and appears to be at least approximately 50-fold greater than that of angiostatin. A synergistic efficacy of endothelial inhibition was observed when angiostatin and kringle 5 (K5) were coincubated with capillary endothelial cells. The synergistic effect is comparable to that produced by K1-5 alone. Systemic treatment of mice with K1-5 at a low dose significantly blocked the fibroblast growth factor-induced corneal neovascularization, whereas angiostatin had no effect at the same dose. K1-5 also suppressed angiogenesis in chicken embryos. Systemic administration of K1-5 at a low dose at which angiostatin was ineffective significantly suppressed the growth of a murine T241 fibrosarcoma in mice. The antitumor effect correlates with the reduced neovascularization. These findings suggest that the plasmin-mediated proteolysis may be involved in the negative switch of angiogenesis.

Angiostatin-mediated suppression of cancer metastases by primary neoplasms engineered to produce granulocyte/macrophage colony-stimulating factor

We determined whether tumor cells consistently generating granulocyte/macrophage colony- stimulating factor (GM-CSF) can recruit and activate macrophages to generate angiostatin and, hence, inhibit the growth of distant metastasis. Two murine melanoma lines, B16-F10 (syngeneic to C57BL/6 mice) and K-1735 (syngeneic to C3H/HeN mice), were engineered to produce GM-CSF. High GM-CSF (>1 ng/10(6) cells)- and low GM-CSF (<10 pg/10(6) cells)-producing clones were identified. Parental, low, and high GM-CSF-producing cells were injected subcutaneously into syngeneic and into nude mice. Parental and low-producing cells produced rapidly growing tumors, whereas the high-producing cells produced slow-growing tumors. Macrophage density inversely correlated with tumorigenicity and directly correlated with steady state levels of macrophage metalloelastase (MME) mRNA. B16 and K-1735 subcutaneous (s.c.) tumors producing high levels of GM-CSF significantly suppressed lung metastasis of 3LL, UV-2237 fibrosarcoma, K-1735 M2, and B16-F10 cells, but parental or low-producing tumors did not. The level of angiostatin in the serum directly correlated with the production of GM-CSF by the s.c. tumors. Macrophages incubated with medium conditioned by GM-CSF- producing B16 or K-1735 cells had higher MME activity and generated fourfold more angiostatin than control counterparts. These data provide direct evidence that GM-CSF released from a primary tumor can upregulate angiostatin production and suppress growth of metastases.