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

In primary malignant brain tumors increased vascularity and marked edema strongly suggest a possible role of the vascular endothelial growth factor/vascular permeability factor (VEGF/VPF). This was confirmed by earlier in situ hybridization studies, by analysis of the expression of the mitogen in different subsets of glioblastoma cells, and by the fact that the VEGF/VPF receptor flt-1 (fms-like tyrosine kinase) is up-regulated in tumor cells in vivo. To assess and quantify the expression of the VEGF/VPF gene and of the receptor gene, 26 surgical specimens of brain tumor tissue from 24 patients were analyzed. In most malignant gliomas, the expression level of the VEGF/VPF gene is elevated and can be increased up to 20- to 50-fold in comparison with low-grade tumors. Using polymerase chain reaction-based amplification, it could be shown that the messenger RNAs of three different VEGF/VPF forms are synthesized in tumor tissue samples. Northern blot studies revealed that in some samples a significant expression of the gene coding for placenta growth factor, a growth factor closely related to VEGF/VPF, was observed. In addition, using a radioreceptor assay it was possible to detect high VEGF/VPF-like activity in the cyst fluids of brain tumors, indicating the accumulation of the mitogen and permeability factor in brain tumor cysts. Further investigations revealed that astrocytoma and glioblastoma cells in culture express the VEGF/VPF gene and secrete the VEGF/VPF protein, whereas gene expression of the two known VEGF/VPF receptors, kinase insert domain-containing receptor and flt-1, could not be detected. These data support previous reports, which stated that VEGF/VPF acts as a paracrine growth and permeability factor in brain tumors and may contribute to tumor growth by initiating tumor angiogenesis.
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PMID:Detection and quantification of vascular endothelial growth factor/vascular permeability factor in brain tumor tissue and cyst fluid: the key to angiogenesis? 752 59

We investigated the mechanism(s) by which systemic administration of doxorubicin (DXR) produced growth retardation of B16 melanomas in the subcutis of syngeneic mice. DXR or saline was injected intravenously (i.v.) into C57BL/6 mice, and B16-BL6 cells were implanted subcutaneously (s.c.) on day 3, 7, or 21 after DXR treatment. In the DXR-pretreated mice, the tumors grew at a slower rate than in control (saline-treated) mice. The experiments were repeated with a B16 variant resistant to DXR with similar results. Tumor growth retardation correlated with extent of myelosuppression monitored by counting bone marrow cells, circulating leukocytes and peritoneal macrophages. In DXR-pretreated mice reconstituted with 1 x 10(7) viable syngeneic spleen cells, the s.c. tumors grew at a rate similar to that in control mice. DXR treatment and spleen cell reconstitution experiments were repeated in BALB/c athymic nude mice. The results were very similar. The growth of s.c. tumors was directly correlated with the degree of peritumoral vascularity. These data indicate that in addition to its well-documented direct antitumor effects, DXR may produce retardation of tumor growth by producing myelosuppression and, hence, inhibition of host cell-induced tumor angiogenesis.
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PMID:Leukocyte-induced angiogenesis and subcutaneous growth of B16 melanoma. 752 86

Angiogenesis, the induction of new capillaries and venules, has been associated with tumor growth. Increased tumor size and new vessel growth may further the opportunity for tumor cells to enter the circulation and potentiate metastatic disease. To investigate if tumor angiogenesis could serve as a prognostic factor in cervical carcinoma, we counted microvessels (capillaries and venules) in 29 patients with squamous cell carcinoma of the cervix. Surgical specimens were stained for endothelial cells specifically with Factor VIII to identify all vessels. The microvessels were counted by light microscopy (per 200 x field) in tumor sections with the highest population of microvessels. This was performed by two investigators without knowledge of patient outcome or extent of disease. Microvessel counts in patients with squamous cell carcinoma were significantly different from those of control subjects: 56 +/- 28.9 and 16.3 +/- 3.3 (P = 0.013). There was no correlation between microvessel count and node status, parametrial involvement, depth of invasion, or gross disease. Microvessel count was significantly correlated with vascular space involvement (P = 0.017). Four patients who developed recurrent disease within 1 year had high microvessel counts and yet were node negative and VSI negative at surgery. As shown by Folkman in breast cancer, angiogenesis may also be an independent predictor for recurrent disease in squamous cell carcinoma of the cervix. Microvessel counts could be of prognostic value in patients who do not have other risk factors for disease recurrence.
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PMID:Tumor angiogenesis as a prognostic factor in cervical carcinoma. 753 19

Angiogenesis is very important not only for embryogenesis and wound healing but also for tumor growth in vivo because vessels supply oxygen and nutrition to the tumor mass. In this study, we focused on Vascular Endothelial Growth Factor (VEGF), a newly characterized endothel-specific growth factor and investigated the expression of VEGF in 13 ovarian tumors and 3 normal ovaries by using polymerase chain reaction (PCR) analysis and Northern blot analysis. Further, we examined the expression pattern of 4 alternatively spliced forms of VEGF in these tissues. The level of VEGF mRNA was higher in 77% of ovarian tumors when compared with that in normal ovaries. Among subtypes of VEGF, 121-, 165- and 189-amino acid types were detected but 206-amino acid type was not observed in ovarian tumors. The most abundant form of VEGF was 121-amino acid type and the relative amounts of the various forms of VEGF were 121-amino acid type > 165-amino acid type >> 189-amino acid type. Expression of flt-1, a receptor for VEGF was detectable by PCR but not by Northern blot analysis. These results suggest that like other epithelial cell-derived carcinomas, ovarian tumors use the VEGF/flt-1 system for tumor angiogenesis.
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PMID:[Expression and subtype analysis of vascular endothelial growth factor (VEGF) and its receptor (flt-1) in human ovarian tumors]. 753 33

The emergence of new cytotoxic agents and techniques for treatment of systemic disease as single modalities or in combination with irradiation and surgery will impact on the use of such agents in the management of systemic breast cancer. Metastatic breast carcinoma, unlike other solid tumors, is highly responsive to chemotherapy, response rates of 50 to 70% have been reported consistently, although there has not been a significant improvement on long-term survival of these patients in the last ten years. New therapeutic approaches include cytotoxic and hormonal agents, growth and differentiation factors, monoclonal antibodies, hematopoietic stem cell support, conquest of tumor cell resistance by MDR-modulation, genetic manipulation, identification of new targets on the tumor surface, synthesis of target-oriented designer-drugs and inhibition of tumor angiogenesis. In breast cancer the tumor growth correlates with vascularization and angiogenesis. Tumor angiogenesis is stimulated by the vascular endothelial growth factor (VEGF). Microvessel density is a significant predictor of survival among node-negative women, who are at risk for having occult metastases at presentation. These patients could then be given systemic adjuvant therapy. Animal experiments show promising inhibition of tumor growth in nude mice after application of antibodies against VEGF. Other methods of manipulation of molecular mechanisms of angiogenesis are under investigation.
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PMID:[Are there alternative forms of therapy in breast carcinoma? Status and perspectives for the treatment of metastasized breast carcinoma]. 753 44

Studies over the past 20 years have established that the development of new capillaries from an existing vascular network (a process called angiogenesis) is an essential component of tumor growth. Malignant tumors do not grow beyond 2-3 mm3 in size unless they stimulate the formation of new blood vessels and thus provide a route for the increased inflow of nutrients and oxygen and outflow of waste products. Tumor angiogenesis also provides an essential exit route for metastasizing tumor cells from the tumor to the bloodstream. Indeed, extensive neovascularization is a poor prognostic factor in several forms of human cancer. Angiogenesis is a complex, multistep process driven by many local signals within the tumor. This involves the degradation of the extracellular matrix around a local venule after the release of collagenases and proteases, the proliferation and migration of capillary endothelial cells, and their differentiation into functioning capillaries. Cytokines produced by various cell types present within the microenvironment of solid tumors form a complex, dynamic network in which they have multiple effects on tumor progression. Herein we review our work on the presence, and possible regulatory influence on tumor angiogenesis, of a number of these cytokines within invasive breast carcinomas. We have combined immunocytochemistry with a single cell cytokine release assay called the reverse hemolytic plaque assay to investigate the cellular sources of the key angiogenic cytokines, vascular endothelial growth factor, basic fibroblast growth factor, and tumor necrosis factor-alpha. Tumor-associated macrophages in the stromal compartment of these tumors and/or malignant epithelial cells were seen to be a major producer cell for these cytokines, whereas tumor necrosis factor-alpha receptors were expressed by leukocytes, malignant cells, and endothelial cells in tumor blood vessels.
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PMID:Cytokine regulation of angiogenesis in breast cancer: the role of tumor-associated macrophages. 753 28

Neovascularization of tumor tissue (tumor angiogenesis) is considered essential for tumor growth, proliferation and eventually metastasis. Microvessel density or count, a measure of tumor angiogenesis, correlates with clinical outcome in skin, breast, lung and prostate carcinomas. To determine whether an association of tumor angiogenesis and nodal metastasis exists in invasive bladder cancer, microvessel counts in 41 primary invasive stages (T2 to 4,NX,M0) bladder cancers were assessed. Microvessels were identified by immunostaining of endothelial cells for factor VIII-related antigen. Microvessels were scored in selected areas showing active neovascularization, either counting a 200 x field (0.74 mm.2) or by using a 10 x 10 square ocular grid (0.16 mm.2). The microvessel count correlated with the presence of occult lymph node metastases (p < 0.0001) by both techniques. The mean microvessel count in 27 patients without lymph node metastases was 56.2 microvessels per 200 x field (standard deviation [SD] 29.5, range 7 to 130) or 28.6 microvessels per grid (SD 14.4, range 4 to 65). The 14 patients with histologically proved lymph node metastases showed mean 138.1 microvessels per 200 x fields (SD 37.9, range 82 to 202) or 74.7 microvessels per grid (SD 14.4, range 43 to 115). Good correlation was noted between area and grid counting (r = 0.97). Tumor T stage, grade and the presence of vascular or lymphatic invasion did not correlate with the presence of lymph node metastases (p = 0.41, 0.59 and 0.26, respectively). Microvessel count may provide important information regarding the risk of occult metastasis in patients with invasive bladder carcinomas.
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PMID:Tumor angiogenesis correlates with lymph node metastases in invasive bladder cancer. 753 69

The aim of this work was to develop a system for noninvasive, in vivo, and in situ study of tumor angiogenesis in awake mice. Tumor spheroids were prepared from Lewis lung carcinoma cells prelabeled with methylrhodamine. A transparent chamber consisting of two titanium frames was implanted into the dorsal skin of CB6 mice. One layer of the skin was removed in a 15-mm area and covered with a coverslip. A few days later, the coverslip was removed and one to three tumor spheroids (diameters, 500-900 microns) were placed over the upper tissue layer. The selected fields were recorded under trans- and epi-illumination using video microscopy. Separate fluorescence filter sets were used to visualize the FITC-labeled plasma and the rhodamine-labeled tumor spheroids. The dual labeling technique allowed precise identification of the tumors and the study of tumor and microvessel growth for up to 14 days. The tumor area and morphometric parameters of tumor vessels were measured from recorded images. After implantation, tumor cells formed well-defined tumor foci. Venular and capillary dilation and tortuosity were observed in the surrounding tissue 1-2 days after implantation, followed by the appearance of buds and sprouts. After that, vascular networks developed around and within the spheroid. During the first week, angiogenesis was very intense: at Day 6, vascular density and tumor area reached 81 and 19% of their respective maximum values. Vascular densities at Days 3, 6, 10, and 14 were 106 +/- 59, 147 +/- 62, 183 +/- 108, and 173 +/- 38 cm-1, respectively. Tumor volume increased exponentially, with a doubling time of 2 days. Similar results were obtained in nude mice. The model allows detailed repeated observations of angiogenesis and permits quantitative evaluation of tumor growth and angiogenesis in vivo. It is applicable for mechanistic studies as well as therapeutic and pharmacokinetic studies of angiostatic and cytotoxic anti-tumor agents.
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PMID:Quantitative angiogenesis in a syngeneic tumor spheroid model. 754 6

Experimental evidence suggests that tumor growth beyond the earliest stages is dependent on angiogenesis, or neovascularization, and that angiogenesis may also promote metastasis. Recent clinical studies demonstrate that angiogenesis is a prognostic marker in breast, lung, and prostate cancer. To investigate whether tumor angiogenesis also correlates with metastasis and survival in early head and neck carcinoma, we quantified the microvascularity of 106 primary carcinomas prior to treatment and correlated the counts with eventual outcome after 3 to 15 years of follow-up. Microvessels were stained immunocytochemically for von Willebrand factor and then counted by light microscopy. Microvessels were counted per 200x and 400x fields, and their density was graded from 1 to 4, in the area of most intense neovascularization. We found that neither microvessel counts nor density grades correlated with metastatic disease, local recurrence, or survival in early head and neck carcinoma. These results are in contradistinction to those recently reported for other tumor sites.
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PMID:Angiogenesis as a prognostic marker in early head and neck cancer. 754 62

We elucidated the relationship between vascular endothelial growth factor/vascular permeability factor (VEGF/VPF), which is a potent angiogenic factor, and the growth of primary and metastatic tumors using an immunoneutralizing monoclonal antibody against human VEGF/VPF121. The monoclonal antibody, MV303, suppressed the growth of human umbilical vein endothelial cells (HUVEC) induced by VEGF/VPF121 or VEGF/VPF165 but did not inhibit its growth induced by basic fibroblast growth factor. MV303 inhibited the binding of 125I-VEGF/VPF121 to HUVEC. We examined the effects of MV303 on tumor angiogenesis using a membrane chamber packed with the human fibrosarcoma cell line HT-1080 and implanted s.c. into BALB/c mice. The neovascularization induced by HT-1080 was inhibited by the i.v. injection of MV303 at a dose of 100 micrograms/mouse. Furthermore, the growth of solid tumors of s.c. implanted HT-1080 in BALB/c nude mice was almost completely inhibited by the i.v. and s.c. administration of MV303 ten times from day 1 at a dose of 100 micrograms/mouse (T/C values of tumor volume at day 18 were 0.20 and 0.18, respectively). Tumor growth was suppressed when MV303 was administered, even from eight days after tumor inoculation. MV303 suppressed the increase in lung weight caused by experimental metastasis with i.v. inoculation of cultured HT-1080 cells to BALB/c nude mice. The life spans of the mice treated with MV303 were significantly prolonged. These results indicated that VEGF/VPF played an important role in both primary and metastatic tumor growth as a tumor angiogenesis factor. MV303, an immunoneutralizing monoclonal antibody against VEGF/VPF, potently inhibited both primary and metastatic tumor growth with no marked side effects.
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PMID:Inhibition of tumor growth and metastasis by an immunoneutralizing monoclonal antibody to human vascular endothelial growth factor/vascular permeability factor121. 758 91


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