Beta-adrenergic receptor-mediated growth of human airway epithelial cell lines.

Abnormal growth of airway epithelium and the resultant thickening of airway walls may produce narrowing of airway calibre, thereby contributing to deterioration of bronchoconstriction in chronic obstructive pulmonary disease (COPD). Beta2-adrenergic agonists have been widely used for the treatment of COPD, but their effects on the growth of airway epithelial cells is unknown. Growth of three human airway epithelial cell lines was studied in vitro. Exposure to salbutamol in serum-free medium increased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide reduction and intracellular deoxyribonucleic acid (DNA) contents in 16-human bronchial epithelium (16-HBE) cells and NCI-H292 cells, but not in A549 cells. The growth-promoting effect of salbutamol in 16-HBE cells was equipotent to 10% foetal bovine serum and was inhibited by propranolol and a cyclic adenosine monophosphate (cAMP) antagonist, Rp-adenosine 3',5'-cyclic monophosphorothioate triethylammonium salt (Rp-cAMPS). Likewise, forskolin and 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) caused cell growth and DNA synthesis. Western blot analysis showed that salbutamol, forskolin, and 8-Br-cAMP each induced expression of the phosphorylated form of mitogen-activated protein (MAP) kinase, and that the salbutamol-induced phosphorylation was inhibited by propranolol, Rp-cAMPS, and the MAP kinase-kinase inhibitor PD98059. These results suggest that in certain airway epithelial cell lines stimulation of beta2-adrenergic receptors and the consequent production of cyclic adenosine monophosphate may upregulate cell growth, probably through activation of the mitogen-activated protein kinase cascade.     

Vascular endothelial growth factor and endoglin expression in colorectal cancer

Purpose and methods

Vascular endothelial growth factor (VEGF) overexpression has been associated with advanced stage and poor survival in several cancers. Additionally, endoglin was proposed as a marker of neovascularization in solid malignancies. The aim of this study was to evaluate the association between the VEGF and endoglin expression in colorectal carcinoma patients, as well as to correlate the VEGF and endoglin expression with standard parameters, to define their potential prognostic role. VEGF and endoglin expression were evaluated in 99 unrelated patients with colorectal cancer using immunohistochemistry.

Results

Vascular endothelial growth factor and endoglobin expression were positively interrelated. No significant correlation of VEGF and endoglin expression with clinicopathological parameters was observed in our cases. The Kaplan–Meier survival curves have demonstrated a clear association of cancer-specific overall survival with high VEGF, as well as high endoglin expression.

Conclusion

Our results support that VEGF and endoglin act as two valuable indicators of prognosis.     

Vascular endothelial growth factor gene and protein: strong expression in thyroiditis and thyroid carcinoma

Angiogenesis is implicated in several pathological conditions, such as inflammation and tumor growth. Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is a potent stimulator of endothelial cell proliferation in vitro and in vivo. The present work aimed to compare VEGF expression in human normal thyroid glands, thyroiditis tissue and thyroid carcinomas using immunohistochemistry and in situ hybridization (ISH). Both chronic lymphocytic thyroiditis and differentiated thyroid carcinomas were found to strongly express VEGF mRNA and encode larger amounts of VEGF than normal thyroid tissue as attested by a VEGF immunostaining score. In addition, tumor samples from patients with metastases showed a higher immunostaining score than their non-metastatic counterparts (P<0.05). Carcinomas with the greatest contents of VEGF mRNA and VEGF protein had the most intense mitogenic activity. Special focus on endothelial cells showed intense mitogenic activity in neoplastic tissues in contrast to the total quiescence of endothelial cells in non-tumoral tissues. An intense VEGF production by differentiated thyroid carcinoma, attested either by a higher immunostaining score or a strong VEGF mRNA expression using ISH, could be a promising marker of tumor aggressiveness and may also be useful as a predictor of metastatic potential.     

Vascular endothelial growth factor

An understanding of the mechanisms regulating growth and differentiation of vascular endothelial cells is very important for cardiovascular biology and medicine. Several potential regulators of angiogenesis have been identified, including acidic and basic fibroblast growth factors, epidermal growth factor, platelet-derived endothelial cell growth factor, transforming growth factors and β, and tumor necrosis factor (TNF-). Vascular endothelial growth factor (VEGF) is unique among these agents by virtue of its direct and specific mitogenic effects on endothelial cells combined with the fact that it is a secreted polypeptide. By alternative splicing of mRNA, VEGF may exist in four different isoforms that have similar biologic activities but differ markedly in their secretion pattern. VEGF is emerging as an important regulator of developmental and ovarian angiogenesis. Its action is purely paracrine as it is produced by a variety of cell types, but its receptors are only in endothelial cells. There is no evidence that endothelial cells in vivo produce VEGF. The VEGF mRNA is expressed at high level by a variety of human tumors, suggesting that VEGF may be a tumor angiogenesis factor. This hypothesis is supported by the finding that monoclonal antibodies specific for VEGF are able to suppress tumor growth in vivo. Therefore, VEGF antagonists may be used for the treatment of malignancies and, possibly, other angiogenic diseases. The VEGF protein has therapeutic potential as an inducer of neovascularization in conditions characterized by impaired tissue perfusion like obstructive atherosclerosis.     

Vascular endothelial growth factor up-regulates cyclooxygenase-2 expression in human endothelial cells

We investigated the effects of vascular endothelial growth factor (VEGF) on cyclooxygenase-2 (COX-2) expression and prostaglandin E(2) (PGE(2)) synthesis in human microvascular endothelial cells (HMEC-1). Treatment of HMEC-1 with VEGF resulted in a dose- and time-dependent up-regulation of COX-2 mRNA and protein levels. This up-regulation was accompanied by a 1.6-fold increase in PGE(2) synthesis. Pretreatment of HMEC-1 with a selective COX-2 inhibitor, NS-398, abolished VEGF-induced PGE(2) synthesis, suggesting specific up-regulation of COX-2 activity by VEGF in HMEC-1. Transient transfection assays using deletion mutants of the human COX-2 promoter fused to the luciferase reporter gene indicated critical requirement of a regulatory region spanning -828/-123 bp for VEGF induction of COX-2 promoter activity in HMEC-1. Site-directed mutation analysis demonstrated that a GATA cis-acting element at -685/-680 bp was essential for VEGF- induced COX-2 promoter activity in HMEC-1. These observations are of particular importance given the recent demonstrations of critical requirement of COX-2 isoenzyme for tumor growth and angiogenesis.     

Vascular endothelial growth factor in pleural fluid.

STUDY OBJECTIVES: The purpose of this study was to analyze the relationship of the pleural fluid vascular endothelial growth factor (VEGF) level with the diagnostic category and with the pleural fluid characteristics in a group of 70 patients. DESIGN: The VEGF levels of consecutive patients undergoing therapeutic thoracentesis were determined with an enzyme-linked immunosorbent assay. SETTING: University-affiliated tertiary care center. RESULTS: The median level of pleural fluid VEGF in the patients with congestive heart failure (150 pg/mL) was significantly (p < 0.05) lower than the median level in the patients with coronary artery bypass grafting (357 pg/mL), which in turn was significantly lower (p < 0.05) than the median levels in the patients with malignancy (1,097 pg/mL). The overlap between groups, however, limits the diagnostic usefulness of pleural fluid VEGF levels. The VEGF level was most closely correlated with the lactate dehydrogenase level (r = 0.42, p < 0.001) and was also significantly correlated with the total pleural fluid protein level. The median VEGF levels in the pleural fluid of patients with breast cancer were significantly lower (p = 0.017) than in those with lung cancer. The VEGF level was very high (3,294 pg/mL) in the one patient with pulmonary embolism. CONCLUSIONS: We conclude that the VEGF levels in pleural fluid differ significantly from one diagnostic category to another with the highest median levels occurring in patients with malignant pleural effusions. We speculate that VEGF may be responsible for the pleural fluid accumulation in at least some situations.     

Vascular endothelial growth factor in Henoch-Schonlein purpura.

OBJECTIVE: To investigate the possible role of vascular endothelial growth factor (VEGF) in the pathogenesis of Henoch-Schonlein purpura (IHSP). METHODS: Plasma VEGF levels were determined in 22 children by ELISA. Ten age matched healthy children served as controls. VEGF expression was evaluated by immunohistochemistry within the cutaneous vasculitic lesion as well as the nonaffected skin and in the skin specimens during the resolution of the disease. RESULTS. Plasma VEGF levels in pg/ml (mean +/- SE) were significantly higher during the acute phase (407.8 +/- 64.92) when compared with the levels seen during the resolution phase (202.17 +/- 26.6; p < 0.002) and in healthy controls (135 +/- 22.8; p < 0.001). Analysis showed that there was a correlation with erythrocyte sedimentation rate. C-reactive protein, white blood cell and platelet count. In all skin specimens, the intensity of the staining of VEGF in the epidermis, dermis, and vascular endothelial bed were evaluated and scored from (+) to (++++). VEGF expression in the epidermis and the vascular bed was more intense in resolving lesions compared with acute vasculitic lesions (p < 0.05). CONCLUSION: Our results suggest that as a potent permeability, chemotactic, and migratory factor, VEGF may play a crucial role in the morphological and functional changes of the vascular bed and inflammatory reaction in HSP.     

Vascular endothelial growth factor and microvascular permeability.

Vascular Endothelial Growth Factors (VEGFs) are endogenously produced vascular cytokines which result in angiogenesis, vasodilatation, and increased microvascular permeability in vivo. They are endothelial specific and result in mitosis, migration, stress fiber formation and increased permeability of endothelial cells in culture. They have been critically implicated in a host of pathological conditions including solid tumor growth and diabetes, and been proposed as a therapy for coronary and peripheral ischemic disease. However, the potent permeability-enhancing properties of VEGFs are very poorly understood. The pharmacology, signal transduction pathways, intracellular signaling mechanisms, and ultrastructural changes which result in increased permeability are still not clear. This review discusses the available evidence for how VEGFs increase permeability in vivo, and some of the pitfalls in interpreting experiments which do not take into account the vasoactive properties of VEGFs. It also discusses the clinical implications of the permeability enhancing effect of VEGFs, and the relevance of these studies to development of new therapies.     

Vascular endothelial growth factor gene polymorphisms in giant cell arteritis

OBJECTIVE: To examine potential associations of vascular endothelial growth factor (VEGF) gene polymorphisms with giant cell arteritis (GCA) and disease expression, in particular in patients with and without ischemic complications. METHODS: We enrolled 92 consecutive patients with biopsy-proven GCA residing in Reggio Emilia, Italy. Two hundred healthy blood donors from the same geographic area were selected as controls. All the GCA patients and controls were genotyped by polymerase chain reaction and allele-specific oligonucleotide techniques for 936 C/T and 634 C/G mutations and for an 18 bp insertion/deletion (I/D) polymorphism in the VEGF promoter region. In vitro release of VEGF by peripheral blood mononuclear cells (PBMC) was investigated by ELISA in controls homozygous for the polymorphisms studied. RESULTS: The carriage rates of the alleles I and C634 were significantly more frequent in GCA patients than in controls (p = 0.025, OR 1.9, 95% CI 1.1-3.1 and p = 0.015, OR 2.1, 95% CI 1.1-3.6, respectively). The distribution of allele T936 was similar in GCA patients and controls. No significant differences in the distribution of the polymorphisms studied were observed in patients with ischemic manifestations compared to those without ischemic manifestations. Lipopolysaccharide (LPS)-stimulated VEGF production by PBMC from controls was higher in II homozygous compared to DD homozygous patients. CONCLUSION: Our data indicate that carriers of C634 and I alleles are associated with susceptibility to developing GCA.     

Vascular endothelial growth factor B, a novel growth factor for endothelial cells.

We have isolated and characterized a novel growth factor for endothelial cells, vascular endothelial growth factor B (VEGF-B), with structural similarities to vascular endothelial growth factor (VEGF) and placenta growth factor. VEGF-B was particularly abundant in heart and skeletal muscle and was coexpressed with VEGF in these and other tissues. VEGF-B formed cell-surface-associated disulfide-linked homodimers and heterodimerized with VEGF when coexpressed. Conditioned medium from transfected 293EBNA cells expressing VEGF-B stimulated DNA synthesis in endothelial cells. Our results suggest that VEGF-B has a role in angiogenesis and endothelial cell growth, particularly in muscle.     

Vascular endothelial growth factor triggers signaling cascades mediating multiple myeloma cell growth and migration.

Multiple myeloma (MM) remains incurable, with a median survival of 3 to 4 years. This study shows direct effects of vascular endothelial growth factor (VEGF) upon MM and plasma cell leukemia (PCL) cells. The results indicate that VEGF triggers tumor cell proliferation via a protein kinase C (PKC)-independent Raf-1-MEK-extracellular signal-regulated protein kinase pathway, and migration via a PKC-dependent pathway. These observations provide the framework for novel therapeutic strategies targeting VEGF signaling cascades in MM.     

Vascular endothelial growth factor modulates matrix metalloproteinase-9 expression in asthma

RATIONALE: Vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) are mediators of airway inflammation and remodeling in asthma. OBJECTIVES: This study investigates a potential relationship between VEGF and MMP-9, and the mechanisms by which VEGF signaling regulates MMP-9 expression in asthma. METHODS: We evaluated whether levels of VEGF correlated with levels of MMP-9 in the sputum of asthma patients, and the effect of VEGF receptor inhibitors on MMP-9 expression in murine model of asthma. Measurements and MAIN RESULTS: We have found that levels of VEGF and MMP-9 are significantly higher in the sputum of patients with asthma than in healthy control subjects, and a significant correlation is found between the levels of VEGF and MMP-9. This study with the ovalbumin-induced model of asthma revealed the following typical pathophysiologic features of asthma in the lungs: increased numbers of inflammatory cells of the airways, airway hyperresponsiveness, increased vascular permeability, and increased levels of MMP-9 and VEGF. Administration of VEGF receptor inhibitors reduced the pathophysiologic signs of asthma and decreased the increased expression of MMP-9 after ovalbumin inhalation. CONCLUSIONS: These results indicate that there is a close relationship between VEGF and MMP-9 expression and that inhibition of VEGF receptor down-regulates the expression of MMP-9. These findings suggest that VEGF signaling regulates MMP-9 expression and plays a critical role in initiation and maintenance of asthma.     

Vascular endothelial growth factor: direct neuroprotective effect in in vitro ischemia

Vascular endothelial growth factor (VEGF) is a hypoxia-inducible angiogenic peptide with recently identified neurotrophic effects. Because some neurotrophic factors can protect neurons from hypoxic or ischemic injury, we investigated the possibility that VEGF has similar neuroprotective properties. In HN33, an immortalized hippocampal neuronal cell line, VEGF reduced cell death associated with an in vitro model of cerebral ischemia: at a maximally effective concentration of 50 ng/ml, VEGF approximately doubled the number of cells surviving after 24 h of hypoxia and glucose deprivation. To investigate the mechanism of neuroprotection by VEGF, the expression of known target receptors for VEGF was measured by Western blotting, which showed that HN33 cells expressed VEGFR-2 receptors and neuropilin-1, but not VEGFR-1 receptors. The neuropilin-1 ligand placenta growth factor-2 failed to reproduce the protective effect of VEGF, pointing to VEGFR-2 as the site of VEGF's neuroprotective action. Two phosphatidylinositol 3'-kinase inhibitors, wortmannin and LY294002, reversed the neuroprotective effect of VEGF, implicating the phosphatidylinositol 3'-kinase/Akt signal transduction system in VEGF-mediated neuroprotection. VEGF also protected primary cultures of rat cerebral cortical neurons from hypoxia and glucose deprivation. We conclude that in addition to its known role as an angiogenic factor, VEGF may exert a direct neuroprotective effect in hypoxic-ischemic injury.     

血管内皮生长因子在Ⅱ型胶原诱导的关节炎小鼠关节组织中的表达

目的 研究血管生成因子－血管内皮生长因子（VEGF）在Ⅱ型胶原诱导的关节炎（CIA）形成期的表达及功能。方法 于DBA／1J小鼠皮下注射Ⅱ型胶原制作关节炎模型并进行关节指数评价。用酶联免疫吸附法（ELISA）及免疫组织化学技术,检测关节组织内VEGF和vWF含量,以及通过RT－PCR,Southern blotting技术检测VEGF mRNA表达。结果 VEGF与vWF呈平行变化关系,均在关节炎发生后第4天达到最高,并与血管新生程度、关节炎严重程度呈正相关。VEGF mRNA在关节组织内表达形式为279、304bp。结论 VEGF在关节炎形成早期起着重要作用,影响着实验诱导关节炎血管新生及进展。