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Query: UMLS:C1519670 (tumor angiogenesis)
 6,052 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A model for the study of tumor angiogenesis within the rabbit brain is presented. Implantation of the VX2 carcinoma provides a reproducible tumor accompanied by angiogenesis. The authors report the sequential growth, histology, tumor neovascularization, and vascular permeability of this tumor following its intracerebral implantation. Tumor angiogenesis correlates with the rapid and logarithmic intracerebral tumor growth. The proliferation of blood vessels in the tumor and the organization of tumor cells around tumor vessels are described. Breakdown of the blood-brain barrier (detected by Evans blue leakage) starts in the early stages of tumor development and becomes prominent as the tumor vasculature and size increase. This model is useful for experimental studies of angiogenesis.
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PMID:Neovascularization and tumor growth in the rabbit brain. A model for experimental studies of angiogenesis and the blood-brain barrier. 245 89

The immunohistochemistry of the epidermal growth factor receptor (EGFR) was studied with monoclonal antibodies in 12 meningiomas of various histologic subtypes, nine benign and three malignant. Strong immunoreactivity of EGFR epitopes was found in the endothelia of the tumor vasculature in six cases. A much weaker reaction was detected within tumor cells in six cases, in one of which it was diffuse and five focal. No correlation was established between the presence of EGFR epitopes and the histologic type or biologic behavior of the meningiomas. The results suggest that the EGFR may participate in tumor angiogenesis, but its role in the growth of neoplastic meningioma cells remains elusive.
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PMID:Epidermal growth factor receptor in meningiomas is expressed predominantly on endothelial cells. 305 82

To investigate the relationship between tumor angiogenesis and the expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/dThdPase) and between patients' survival and the expression of PD-ECGF/ dThdPase in human gastric carcinoma tissues, we performed immunohistochemical studies with anti-PD-ECGF/dThdPase and anti-CD34 monoclonal antibodies. Out of 154 gastric carcinoma tissue samples, 61 (40%) were evaluated as PD-ECGF/ dThdPase-positive. The expression of PD-ECGF/dThdPase was significantly associated with the intratumoral microvessel counts (P < 0.0001) and the incidence of hematogenous metastasis (P < 0.05). Intratumoral vessel counts were significantly correlated with overall survival of 154 patients (P < 0.000001). Cox proportional hazards model showed that tumor vasculature was an independent and strong prognostic variable. However, the prevalence of the expression of PD-ECGF did not associate the overall survival. We suggest that expression of PD-ECGF/dThdPase plays a role in the promotion of angiogenesis in human gastric carcinomas, without any definite influence on patient's survival.
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PMID:Tumor angiogenesis and expression of thymidine phosphorylase/platelet derived endothelial cell growth factor in human gastric carcinoma. 897 6

The phenomenon of tumor angiogenesis is an important aspect of understanding tumor biology. Studies in breast carcinoma have shown microvessel density (MVD) assessed by immunohistochemistry to be of prognostic importance in primary breast cancer. On the other hand, recently developed highly sensitive color-coded Doppler techniques offer a noninvasive method to examine neovascularisation in breast tumors. The purpose of this study was to determine the relationship between Doppler flow parameters and microvessel count assessed by immunohistochemistry. Fifty-three patients with primary breast cancer were examined preoperatively with color-coded Doppler ultrasound. The obtained Doppler frequency spectra were analyzed for peak systolic flow velocity (Vmax). Following surgery, paraffin-embedded microsections were immunohistochemically stained for factor VIII-related antigen. Tumor angiogenesis was assessed by microvessel count under light microscopy. Undifferentiated tumors correlated with high MVD (p=0.009) whereas other clinicopathological parameters were not associated with MVD. Color Doppler signals were detected in 50 out of 53 breast tumors. Evaluation of tumor flow velocity with various clinicopathological parameters showed a significant correlation with tumor size (p=0.0001) and lymph node metastasis (p=0.02). However, there was no significant correlation between MVD and intratumoral blood flow velocity assessed by color-coded Doppler. Our findings showed that Doppler flow measurement did not correlate with the extent of tumor angiogenesis of breast cancer. The present data give circumstantial evidence that microvessel count assessed by immunohistochemistry reflects the microvascular network, whereas tumor vasculature documented by Doppler ultrasound supplies information on the macrovasculature.
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PMID:Color-coded and spectral Doppler flow in breast carcinomas--relationship with the tumor microvasculature. 949 79

Administration of tumor necrosis factor (TNF) and gamma interferon (IFN-gamma) to melanoma patients causes selective disruption of the tumor vasculature but the mechanism of this disruption is unknown. Here we report that exposure of human endothelial cells to TNF and IFN-gamma results in a reduced activation of integrin alphaVbeta3, an adhesion receptor that plays a key role in tumor angiogenesis, leading to a decreased alphaVbeta3-dependent endothelial cell adhesion and survival. Detachment and apoptosis of angiogenic endothelial cells was demonstrated in vivo in melanoma metastases of patients treated with TNF and IFN-gamma. These results implicate integrin alphaVbeta3 in the anti-vascular activity of TNF and IFN-gamma and demonstrate a new mechanism by which cytokines control cell adhesion.
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PMID:Evidence for the involvement of endothelial cell integrin alphaVbeta3 in the disruption of the tumor vasculature induced by TNF and IFN-gamma. 954 82

Angiogenesis, the process by which new blood vessels are generated, occurs during wound healing, in the female reproductive system during ovulation and gestation, and during embryonic development. The process is carefully controlled with positive and negative regulators, because several vital physiological functions require angiogenesis. The consequences of abnormal angiogenesis are either excessive or insufficient blood vessel growth. Ulcers, strokes, and heart attacks can result from the absence of angiogenesis normally required for natural healing, whereas excessive blood vessel proliferation may favor tumor growth and dissemination, blindness, and arthritis. In this review, the process of angiogenesis and the characteristics of the resulting tumor vasculature are outlined. Contrast-enhanced magnetic resonance imaging techniques that currently are available for basic research and clinical applications to study various aspects of tumor angiogenesis and neovascularization are discussed.
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PMID:Tumor angiogenesis, vascularization, and contrast-enhanced magnetic resonance imaging. 1055 24

The degree of tumor malignancy generally correlates to tumor grade, and the direct measurement of tumor vasculature is desired. Dynamic susceptibility contrast magnetic resonance imaging can provide relative cerebral blood volume and, therefore, is one of the most reliable methods to evaluate tumor vasculature in vivo. Tumor vessel size is extremely variable due to complex tumor angiogenesis, and the gradient-echo echo-planar imaging (GE-EPI) technique, which is sensitive to the total vascular bed, is well suited for this purpose. As many studies have shown, dynamic susceptibility contrast magnetic resonance imaging is more useful for grading glioma than conventional magnetic resonance imaging. We found that this technique can also provide supplementary information to differentiate between malignant lymphoma and glioma because the absence of tumor neovascularization of malignant lymphoma leads to low rCBV, which is in contrast to those of malignant gliomas. Indeed, this technique can be used for the differentiation of extra-axial tumors such as between meningioma and neurinoma. Recently, this technique has been focused toward determining the stereotactic biopsy site, monitoring the embolization of effect in meningioma, or evaluation of treatment effects after radiation therapy. However, the value of tumor rCBV is affected by many conditions such as the T1 relaxivity effects of gadolinium in the extravascular space. To establish the usefulness of this technique, further examination will be needed.
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PMID:Value of dynamic susceptibility contrast magnetic resonance imaging in the evaluation of intracranial tumors. 1055 26

Numerous laboratories are focusing efforts on delivering gene products to induce or prevent the development of new blood vessels in adults, with the hope of rescuing ischemic tissues, circumventing cardiac bypass surgery, or inhibiting tumor growth. Current approaches to the assessment of vascular continuity involve the introduction of either dyes or fluorescent microspheres to track blood flow. However, dyes and dextrans are subject to leakage when vessels are hyperpermeable, a situation that may occur in studies of tumor vasculature and during efforts to stimulate therapeutic angiogenesis. Furthermore, the microspheres that are used for flow studies do not allow a comprehensive visual analysis of vascular continuity. Here we report a method for the visual assessment of microvascular continuity in mouse muscle under circumstances in which vessels are leaky. The approach involves perfusion of the vasculature with fluorescent beads that are much smaller than those used for flow studies. The suspension behaves like a fluid and completely fills the vessels, yet the beads do not leak from VEGF-permeablized capillaries and remain localized in histological sections. Use of beads with the proper fluorescence emission wavelengths allows immunofluorescent colocalization with vessel-specific markers. We compare this improved method with other methods for tracking vascular continuity involving dextrans and larger beads. This approach should aid in the dynamic study of tumor angiogenesis and the evaluation of efforts to deliver angiogenic factors.
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PMID:Angiogenesis monitored by perfusion with a space-filling microbead suspension. 1093 15

Angiostatin is an inhibitor of tumor angiogenesis that induces regression of experimental tumors and enhances the antitumor effects of radiation therapy. We report that the cytotoxic effects of angiostatin are restricted to the proliferating endothelial cell population. In addition, angiostatin and ionizing radiation (IR) interact by inducing death of dividing endothelial cells. We also show that angiostatin and IR interact to inhibit endothelial cell migration. These findings demonstrate that angiostatin targets the proliferating tumor vasculature and provide a mechanistic basis for the cytotoxic interaction of angiostatin and IR.
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PMID:Angiostatin induces mitotic cell death of proliferating endothelial cells. 1096 51

Antiangiogenic therapy is a promising new strategy to inhibit tumor growth and formation of metastases. Vascular endothelial growth factor (VEGF) and its receptors, VEGF-receptor 1 (VEGF-R1; FLT-1) and VEGF-R2 (KDR), have been shown to play a major role in tumor angiogenesis. PTK787/ZK 222584, a specific inhibitor of both VEGF-receptor tyrosine kinases, was investigated for its antitumoral and antiangiogenic activity in a murine renal cell carcinoma model. After intrarenal application of the renal carcinoma cells, mice develop a primary tumor and metastases to the lung and to the abdominal lymph nodes. Daily oral therapy with PTK787/ZK 222584 at a dose of 50 mg/kg resulted in a significant decrease of 61 and 67% in primary tumors after 14 and 21 days, respectively. The occurrence of lung metastases was significantly inhibited at both time points (98% reduction and 78% reduction, respectively). After 14 days, no lymph node metastases developed in the PTK787/ZK 222584-treated group, whereas after 21 days of treatment, the lymph node metastases were reduced by 87%. Vessel density in tumor tissues, detected by immunohistochemistry with an anti-CD31 antibody, was significantly decreased by PTK787/ZK 222584. Using color Doppler imaging ultrasound, significant changes in blood flow in the tumor feeding renal artery were found under treatment with PTK787/ZK 222584. Blood flow changes correlated with changes in vessel density but not with tumor volume. The compound was well tolerated in all in vivo experiments and had no significant effects on body weight or general well-being of the animals. This was in contrast to the animals treated with the antiangiogenic agent TNP-470. s.c. therapy with 30 mg/kg TNP-470 every other day had to be discontinued after 13 days because of animal weight loss (>20%) and ataxia. These results demonstrate that PTK787/ZK 222584 is a potent inhibitor of tumor growth, metastases formation, and tumor vascularization in murine renal cell carcinoma. Furthermore, we have been able to demonstrate that color Doppler imaging ultrasound can be used to measure blood flow to a tumor and that flow correlates with vessel density. Thus, this may be a valuable noninvasive method for monitoring the effects of antiangiogenic agents such as PTK787/ZK 222584 on tumor vasculature.
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PMID:Effects of PTK787/ZK 222584, a specific inhibitor of vascular endothelial growth factor receptor tyrosine kinases, on primary tumor, metastasis, vessel density, and blood flow in a murine renal cell carcinoma model. 1098 92


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