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Changes of expressions of VEGF, bFGF, and angiogenesis, and effect of benazepril, bFGF on angiogenesis in acute myocardial infarction model of the rabbits.

OBJECTIVE: To explore the changes of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and angiogenesis, and the effects of bFGF, angiotensin converting enzyme inhibiter(ACEI) benazepril on the angiogenesis in acute myocardial infarction (AMI) model of rabbits, and to provide a probable evidence for the treatment of AMI. METHODS: AMI model was established by ligating anterior descending branch of coronary artery of Japan-Sino hybridization white rabbits. The postoperative rabbits were randomly divided into 6 groups and each group was treated with different drugs. Groups 1 and 2 were treated with normal saline (NS) for 28 and 14 days (d), group 3 and 4 with bFGF for 28 and 14 d, groups 5 with benazepril for 14 d, and group 6 with benazepril and bFGF for 14 d respectively. The rabbits were killed on the 14th or 28th d and their hearts were excised, sectioned and stained with HE, Masson trichrome to observe VEGF, bFGF and CD(34) under a microscope, which were quantified with a computer-assisted morphometry. RESULTS: Compared with group 1, the granulation tissue of infarction zone (IZ) in group 2 freshened up, and the capillary density (CD) in IZ was increased (P = 0.002). The CD in the IZ as well as VEGF and bFGF in groups 3 and 4 were increased respectively (P = 0.011-0.037). In group 5 the changes of VEGF and bFGF were not found in the IZ and the border zone (BZ) while CD was significantly increased (35.4% and 25.6%, P = 0.036 and 0.037). Compared with group 2, the CD in the IZ and BZ of group 6 was significantly increased (63.4% and 44.3% P = 0.007 and 0.007), meanwhile VEGF and bFGF were increased. Compared with group 5, only VEGF was increased. CONCLUSION: Intravenous bFGF may increase VEGF and bFGF significantly, thus promoting the angiogenesis in the IZ and BZ in cardiac infarction as VEGF and bFGF are the potent angiogenic growth factors. Benazepril may promote angiogenesis in the IZ and BZ in cardiac infarction, but its mechanism is irrelative to the expression of VEGF and bFGF. The combination of benazepril and bFGF may promote, to some extent, the expression of VEGF and bFGF, but their effect on angiogenesis has not been found.

Angiotensin-Converting Enzyme Inhibitors↗

[Angiogenesis and anti-angiogenesis in human neoplasms. Recent developments and the therapeutic prospects].

Angiogenesis entails new vessel formation from preexisting vessels. It follows vasculogenesis during embryo development. In post-natal life, it occurs both in physiological conditions (wound repair and cyclically in the female genital system) and pathological conditions such as tumors. Several sequential steps are involved, including basement membrane degradation by proteolytic enzymes secreted by the endothelial cells, chemotaxis toward the stimulus and proliferation of these cells, canalization, branching and formation of vascular loops, stabilization and functional maturation of neovessels following perivascular apposition of pericytes and smooth muscle cells, and neosynthesis of basement membrane constituents. Tumor angiogenesis is regulated by several factors, mainly growth factors for the endothelial cells secreted by both the tumor and host inflammatory cells, and mobilized from extracellular matrix stores by proteases secreted by tumor cells. Regulatory factors also include the extracellular matrix components and endothelial cell integrins, hypoxia, oncogenes and tumor suppressor genes. Angiogenesis is mandatory to the process of tumor progression (growth, invasion and metastasis), since it conveys oxygen and metabolites, whereas endothelial cells secrete growth factors for tumor cells and a variety of proteinases which facilitate invasion and increase opportunities for tumor cells to enter the circulation. We present our results concerning the relationship between angiogenesis and progression in patients with melanoma, multiple myeloma, B-cell non-Hodgkin's lymphomas and mycosis fungoides. Lastly, it is becoming increasingly evident that agents interfering with blood vessel formation also interfere with tumor progression. These include antagonists of angiogenic growth factors, angiogenic receptors, endothelial cell integrins, and proteolytic enzymes, as well as non-specific toxic agents for vessels and low-dose chemotherapeutic agents. Their recent applications in preclinical models and in neoplastic patients are reviewed.

Angiogenesis Inducing Agents↗

Chorioallantoic membrane capillary bed: a useful target for studying angiogenesis and anti-angiogenesis in vivo.

The chick embryo chorioallantoic membrane (CAM) is an extraembryonic membrane that is commonly used in vivo to study both angiogenesis and anti-angiogenesis. This review 1) summarizes the current knowledge about the structure of the CAM's capillary bed; 2) discusses the controversy about the existence of a single blood sinus or a capillary plexus underlying the chorionic epithelium; 3) describes a new model of the CAM vascular growth, namely the intussusceptive mode; 4) reports findings regarding the role played by endogenous fibroblast growth factor-2 in CAM vascularization; and 5) addresses the use and limitations of the CAM as a model for studying angiogenesis and anti-angiogenesis.

Allantois↗

Angiogenesis-dependent diseases and angiogenesis therapy.

The discovery of the molecular mechanisms of physiological vasculogenesis and pathological angiogenesis helped to recognize two classes of diseases: one where the therapeutic angiogenesis can repair the tissue damages (arteriosclerosis, myocardial infarction, limb ischemia) and the other one where inhibition of pathological angiogenesis can cure the disease or delay its progression (retinopathies, benign and malignant angiogenic tumors, progression of malignant tumors). Although there are an exponentially growing number of new synthetic molecules characterized mainly by antiangiogenic properties, the discovery of a large battery of natural pro- and anti-angiogenic factors suggests that this may provide a more physiological approach to treat both class of angiogenesis-dependent diseases in the near future.

Angiogenesis Inhibitors↗

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗

Angiogenesis and anti-angiogenesis in hematological malignancies.

Although it is well established that the growth of solid tumors requires vigorous neovascularization, it has been assumed that leukemias and other hematological malignancies do not depend on angiogenesis. However, the role of angiogenesis in growth and survival of neoplastic cells of the hematopoietic system has recently been recognized, and provides a rationale for novel therapeutic approaches to hematological malignancy. This review summarizes the literature concerning the relationship between angiogenesis and disease progression of several hematological malignancies. It is becoming increasingly evident that agents that interfere with blood vessel formation also block tumor progression, and, accordingly, antiangiogenic therapy has gained much interest as a potential adjunct to conventional therapy of many hematological malignancies. Recent successful applications of antiangiogenic agents that interfere or block the progression of hematological malignancies are evaluated in light of recent demonstrations of potent angiogenic activity of several hematopoietic growth factors. A novel finding regarding the role of angiogenesis in hematological malignancies, which accounts for many clinical observations as well as the apparent independence of these tumors on marrow vascularity, is presented. The information presented in this review will facilitate the design of future clinical trials using antiangiogenic agents for the treatment of hematological malignancies and will provide a basis for the design of experiments undertaken to define the mechanisms involved, mechanisms that may shed new light on the pathology of hematological malignancies.

Angiogenesis Inhibitors↗

Two-dimensional models of tumour angiogenesis and anti-angiogenesis strategies.

There is a very strong link between the vascularization of a tumour and the spread of the disease, both locally and to distant sites (Gimbrone et al., 1974, J. Natl. Cancer Inst. 52, 413-27; Muthukkaruppan et al., 1982, J. Natl. Cancer Inst. 69, 699-704; Ellis & Fiddler, 1995, Lancet 346, 388-9). A tumour becomes vascularized by a process known as angiogenesis. Tumour angiogenesis is initiated by the release of diffusible substances by the tumour, whereby neighbouring capillary vessels are stimulated to grow and eventually penetrate the tumour. Anti-angiogenesis has been proposed as a potential strategy for the treatment of cancer (Folkman, 1995, Nature Med. 1, 21-31; Harris et al., 1996, Breast Cancer Res. Treat. 38, 97-108). In this paper, a mathematical model of the development of the tumour vasculature is presented. By suitable manipulation of the model parameters, we simulate various anti-angiogenesis strategies and we examine the roles that haptotaxis and chemotaxis may play during the growth of the neovasculature. The model is simulated in two space dimensions (on a square domain) so that it is, in theory, experimentally reproducible and any predictions of the model can therefore be tested.

Angiogenesis Inducing Agents↗

Levels of angiogenesis and expression of angiogenesis-related genes are prognostic for organ-specific metastasis of renal cell carcinoma.

BACKGROUND: To identify organ-specific, metastasis-related factors that can be used to predict the development and location of metastasis of clear cell renal cell carcinoma (CRCC), the authors assessed the angiogenesis and the expression of angiogenesis-related genes in primary and metastatic tumors. METHODS: They evaluated intratumoral microvessel density (MVD) by immunohistochemical staining, assessed the expression of angiogenesis-related genes by mRNA in situ hybridization, and determined the clinicopathologic characteristics of 92 archival specimens of primary and metastatic CRCCs from 54 patients. All 38 metastatic tumor specimens were resected from 24 patients. RESULTS: The pathologic stage (P=0.026) of the primary tumor specimen was an important predictor for metastasis, as were MVD (P=0.000025) and the ratio of matrix metalloproteinases (MMPs) to E-cadherin (M/E ratio; P=0.000041). In addition, primary tumor specimens resected from patients with metastatic CRCCs had high MVD, high levels of MMP-2 expression, and a high M/E ratio (P <0.05). Relative to the primary tumors, the metastatic tumors also had high MVD, overexpression of basic fibroblast growth factor, vascular endothelial growth factor, interleukin-8, MMPs, and a high M/E ratio (P <0.05). Multivariate analysis revealed that MVD and the M/E ratio in the primary tumor were independent prognostic factors for metastasis (P=0.049 and P=0.001, respectively). Furthermore, the M/E ratio in metastatic tumor specimens resected from the lung and lymph node was an independent prognostic factor for metastasis (P=0.01823 and P=0.03950, respectively). CONCLUSIONS: The current study indicated that angiogenesis and M/E ratio were specific predictors for metastases of RCC, especially to the lung or lymph node. Therefore, MMPs and E-cadherin could be relevant targets for novel therapeutic strategies to control or prevent the metastasis of RCC.

Aged↗

Controlling the vasculature: angiogenesis, anti-angiogenesis and vascular targeting of gene therapy.

Angiogenesis is the development of new blood vessels from an existing vascular bed. Normal vascular proliferation occurs only during embryonic development, the female reproductive cycle and wound repair. By contrast, many pathological conditions (for example, cancer, atherosclerosis and diabetic retinopathy), are characterized by persistent, unregulated angiogenesis. Conversely, inadequate angiogenesis can lead to failure of ulcers to heal and myocardial infarction. Control of vascular development could permit new therapeutic approaches to these disorders. For example, several anti-angiogenic drugs are currently undergoing clinical trials for the treatment of cancer, whereas enhancement of angiogenesis by exogenous growth factors can prevent or limit the damage in chronic wounds and duodenal ulcers. Here Tai-Ping Fan, Rhys Jaggar and Roy Bicknell highlight recent achievements and discuss the prospects of receptor antagonists, enzyme inhibitors, tumour suppressor genes and vascular targeted approaches, especially that of gene therapy, in the future development of angiotherapy.

Animals↗

Correlation between apoptotic index and angiogenesis in non-small cell lung cancer: comparison between CD105 and CD34 as a marker of angiogenesis.

Only a few clinical studies have documented a significant correlation between intratumoral microvessel density (IMVD), a measurement of angiogenesis, and apoptotic index (AI), an incidence of apoptosis, although many experimental studies have confirmed that insufficient angiogenesis induces accelerated apoptotic cell death. In the present study, therefore, to assess AI in correlation with IMVD in resected non-small cell lung cancer, a total of 236 patients with pathologic stage I to IIIa were reviewed. IMVDs were determined immunohistochemically with an antibody against a pan-endothelial marker, CD34 (CD34-IMVD), and an antibody against a proliferation-related endothelial marker, CD105 (CD105-IMVD). AI was defined as the number of tumor cells positive for the terminal deoxynucleotidyl tranferase-mediated dUTP-biotin nick end-labeling staining per 1000 tumor cells. When CD34 was used as a marker of angiogenesis, the mean AIs for the lower-IMVD and the higher-IMVD patients were 20.1 and 17.5, respectively, demonstrating no significant difference between the lower- and the higher-IMVD patients. In contrast, when CD105 was used, the mean AI for the lower-IMVD patients was significantly higher than that for the higher-IMVD patients (22.0 and 15.6, respectively; P=0.019). There was no significant correlation between proliferative activity and CD34-IMVD or CD105-IMVD. These results demonstrated that that decreased angiogenesis may induce enhanced apoptotic tumor-cell death without affecting cell proliferation.

Aged↗

Angiogenesis induced by hepatocyte growth factor in non-infarcted myocardium and infarcted myocardium: up-regulation of essential transcription factor for angiogenesis, ets.

The feasibility of a novel therapeutic strategy using angiogenic growth factors to expedite and/or augment collateral artery development has recently entered the realm of treatment of ischemic diseases. Hepatocyte growth factor (HGF) is a novel member of endothelium-specific growth factors whose mitogenic activity on endothelial cells is very potent. Although it has been demonstrated that HGF is a potential angiogenic growth factor in in vitro culture systems, there is no direct in vivo evidence for the angiogenic activity of HGF in physiological conditions. In this study, we hypothesized that transfection of HGF gene into infarcted myocardium could induce angiogenesis, potentially resulting in a beneficial response to hypoxia. Human HGF gene or control vector driven by the SRalpha promoter was transfected into rat myocardium by the HVJ-liposome method. Four days after in vivo transfection of human HGF gene, there was a marked increase in human immunoreactive HGF as compared with control vector (P < 0.01). In myocardium transfected with HGF vector, a significant increase in PCNA-positive endothelial cells was observed, while few PCNA-positive endothelial cells were detected in both control-vector-transfected and untreated myocardium. The number of vessels around the HGF injection sites was significantly increased as compared with control vector or vehicle (P < 0.01). Angiogenic activity induced by the transfection of HGF vector was also confirmed by the activation of a transcription factor, ets, which is essential for angiogenesis. Furthermore, we studied the pathophysiological role of HGF in a myocardial infarction model. The concentration of endogenous HGF was significantly decreased in infarcted myocardium. Therefore, we hypothesized that transfection of HGF gene into infarcted myocardium could induce a beneficial response to the decreased endogenous HGF. Indeed, transfection of human HGF into infarcted myocardium also resulted in a significant increase in the number of vessels (P < 0. 01), accompanied by marked induction of ets binding activity and a significant increase in blood flow. Overall, the present results provide direct in vivo evidence for the induction of angiogenesis by transfection of the human HGF gene in rat non-infarcted and infarcted myocardium. The constant production of local HGF resulting from the transgene may be considered as an innovative therapeutic angiogenesis strategy for ischemic diseases such as myocardial infarction. Gene Therapy (2000) 7, 417-427.

Animals↗

In vitro tumor angiogenesis assays: plasminogen lysine binding site 1 inhibits in vitro tumor-induced angiogenesis.

It is generally accepted that tumors are angiogenesis-dependent. For research and clinical purposes it would be very attractive to have a simple in vitro model that allows a rapid screening of the angiogenic potential of tumors and to study the effect of angiogenic inhibitors. In vitro angiogenesis models were developed, based on endothelial sprouting/tube formation on a collagen gel, using both tumor cell lines and tumor biopsies. Best results were obtained using conditioned medium of tumor cell lines. In this model it was found that the plasminogen fragment lysine binding site 1 (LBS-1) inhibited in vitro endothelial cell sprouting. This is the first demonstration that LBS-1, which includes angiostatin, is inhibitory for new vessel formation in an in vitro angiogenesis model. We conclude that the assay system allows for rapid and reliable screening of angiogenesis inhibitors.

Animals↗

Angiogenesis: molecular mechanisms and functional interactions--2nd Kloster Seeon Meeting of the German Priority Research Grant "Angiogenesis".

The German Priority Research Program "Angiogenesis" (www.angiogenese.de) hosts a biannual meeting in the Kloster Seeon in Southern Germany. The 2nd Kloster Seeon Meeting "Angiogenesis: Molecular Mechanisms and Functional Interactions" was held in September 2002. It included sessions on hypoxia, the biology of endothelial precursor cells, angiogenic growth factors including VEGFs, the angiopoietins, ephrins, and FGFs, mechanisms of vascular sprouting and cell-cell contacts during angiogenesis, angiogenic signaling, lymphangiogenesis, angiogenesis during tumor invasion and metastasis, and on novel angiomanipulatory therapies. This report summarizes the key findings reported during the platform presentations of the meeting.

Animals↗

Screening of angiogenesis inhibitors by modified tumor-induced angiogenesis (TIA) test in lung cancer.

Aberrant angiogenesis-the new vessels formation is a mandatory event in the process of tumor growth and expansion. Studies on mechanisms involved in tumor-induced angiogenesis (TIA) and on its possible inhibitors are needed in order to introduce in future new methods of tumor treatment. The aim of our study was to determine the usefulness of the modified cutaneous TIA (mice without immunosuppression) test for screening in vivo of the angiogenesis modifiers. In both models (classical and modified TIA) we demonstrated comparable angiogenesis activity following human lung cells inoculation and similar degree of neovascularization response inhibition caused by theobromine. We reported that in modified TIA model preincubation with theobromine significantly suppressed angiogenic potential of human lung cancer cells as well as the ability of those cells to produce proangiogenic cytokine-bFGF.

Adenocarcinoma↗

Effect of U-995, a potent shark cartilage-derived angiogenesis inhibitor, on anti-angiogenesis and anti-tumor activities.

BACKGROUND: A potent angiogenesis inhibitor, U-995, has been purified from the cartilage of the blue shark (Prionace glauca). U-995 is composed of two single peptides with molecular mass of 10 and 14 kDa, respectively. MATERIALS AND METHODS: U-995 was designed to study human umbilical vein endothelial cell (HUVEC) migration and proliferation in vitro and angiogenesis induced by TNF alpha in chicken chorioallantoic membrane (CAM). Furthermore, we determined the ability of U-995 to inhibiting tumor cell growth and metastasis. RESULTS: U-995 (15 and 30 micrograms/ml) markedly inhibited HUVEC migration and, at 15-50 micrograms/ml produced a dose-dependent decline in [3H]-thymidine incorporation. 30 and 50 micrograms/ml of U-995, when added to TNF alpha-induced angiogenesis caused discontinuous and disrupted blood vessels. Moreover, U-995 (30 micrograms/ml) markedly prevented collagenase-induced collagenolysis. In addition, when 200 micrograms U-995 was injected i.p. into mice it suppressed sarcoma-180 cell growth and B16-F10 mouse melanoma cell metastasis in vivo. CONCLUSIONS: These results suggest that the anti-angiogenic effects of U-995 may be be due to interference with the proliferation and migration of HUVECs as well as inhibition of collagenolysis, thereby leading to inhibition of both angiogenesis and tumor cell growth.

Allantois↗

Recent advances in angiogenesis, anti-angiogenesis and vascular targeting.

Angiogenesis, the development of new blood vessels, has become a major focus of research. This has been stimulated by the therapeutic opportunities offered by the ability to manipulate the vasculature in pathologies such as cancer. Here, we present an overview of recent advances in angiogenesis. Especially noteworthy is the large volume of information from developmental studies, particularly those that involve transgenic and gene knockout mice. We also discuss the increasing repertoire of drugs with which to manipulate angiogenesis and new endothelial-specific genes with which to target the vasculature.

Angiogenesis Inducing Agents↗

Analysis of combination anti-angiogenesis therapy on markers of coagulation, platelet activation and angiogenesis in patients with advanced cancer.

The effects of combination anti-angiogenesis therapy (marimastat, captopril and fragmin) on plasma levels of coagulation initiator tissue factor (TF), platelet marker soluble P-selectin and angiogenic vascular endothelial growth factor (VEGF) were tested in 25 patients with advanced cancer. They had higher soluble P-selectin (P<0.001) and TF (P<0.001), but not VEGF (P=0.066) than 25 age and sex-matched controls. VEGF and TF correlated significantly (r=0.8, P<0.001) in cancer patients. Soluble P-selectin, TF and VEGF did not change at 4- and 8-weeks whilst on treatment. We provide further evidence linking coagulation and angiogenesis but combination anti-angiogenesis therapy does not influence plasma soluble P-selectin, TF or VEGF.

Adult↗

Angiogenesis and anti-angiogenesis in neuroblastoma.

Angiogenesis is a biological process by which new capillaries are formed from pre-existing vessels. It occurs in physiological and pathological conditions, such as tumours, where a specific critical turning point is the transition from the avascular to the vascular phase. Tumour angiogenesis depends mainly on the release by neoplastic cells of growth factors specific for endothelial cells that able to stimulate the growth of the host's blood vessels. This review summarises the literature concerning the relationship between angiogenesis and progression in human neuroblastoma, the most common extracranial solid tumour of infancy and childhood. It is becoming increasingly evident that agents which interfere with blood vessel formation also block tumour progression. Accordingly, anti-angiogenic tumour therapy has gained much interest in preclinical and clinical assessments. The recent applications of anti-angiogenic agents which interfere or block neuroblastoma progression are reviewed.

Angiogenesis Inhibitors↗