Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1519670 (tumor angiogenesis)
 6,052 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), the critical molecule in tumor angiogenesis, is regulated by different stimuli, such as hypoxia and oncogenes, and also by growth factors. Previously we have shown that in AsPC-1 pancreatic adenocarcinoma cells, insulin-like growth factor receptor (IGF-IR) regulates VPF/VEGF expression. Insulin receptor substrate-1 and -2 (IRS-1 and IRS-2), two major downstream molecules of IGF-1R, are known to be important in the genesis of diabetes. In this study, we have defined a new role of IRS in angiogenesis. Both of the IRS proteins modulate VPF/VEGF expression in pancreatic cancer cells by different mechanistic pathways. The Sp1-dependent VPF/VEGF transcription is regulated mainly by IRS-2. Protein kinase C-zeta (PKC-zeta) plays a central role in VPF/VEGF expression and acts as a switching element. Furthermore, we have also demonstrated that the phosphatidylinositol 3-kinase pathway, but not the Ras pathway, is a downstream event of IRS proteins for VPF/VEGF expression in AsPC-1 cells. Interestingly, like renal cancer cells, in AsPC-1 cells PKC-zeta leads to direct Sp1-dependent VPF/VEGF transcription; in addition, it also promotes a negative feedback loop to IRS-2 that decreases the association of IRS-2/IGF-1R and IRS-2/p85. Taken together, our results show that in AsPC-1 pancreatic carcinoma cells, Sp1-dependent VPF/VEGF transcription is controlled by IGF-1R signaling through IRS-2 proteins and modulated by a negative feedback loop of PKC-zeta to IRS-2. Our data also suggest that IRS proteins, which are known to play crucial roles in IGF-1R signaling, are also important mediators for tumor angiogenesis.
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PMID:Role of insulin receptor substrates and protein kinase C-zeta in vascular permeability factor/vascular endothelial growth factor expression in pancreatic cancer cells. 1460 96

Vascular endothelial growth factor (VEGF) is considered a key mediator of tumor angiogenesis, including neovascularization in human breast cancer. High tissue VEGF levels appear to correlate with poor prognosis and decreased overall survival in node-positive and node-negative breast cancer patients. Hormonal regulation of VEGF expression has been demonstrated, and some reports indicate that tamoxifen, a partial estrogen receptor agonist, increases VEGF mRNA in breast cancer cells. These results appear to contradict the efficacy of tamoxifen as an adjuvant for estrogen-dependent breast cancer, yet clinical data show that tamoxifen prevents metastasis and increases overall survival. In this study, we confirmed previous studies showing that intracellular levels of VEGF in vitro increased in response to tamoxifen to levels similar to those observed after estrogen treatment. To further study hormonal effects on the release of VEGF, we used microdialysis to sample the extracellular space, where VEGF is biologically active, in solid tumors in situ. We show for the first time that tamoxifen decreased extracellular VEGF in vivo in solid MCF-7 tumors in nude mice. These in vivo findings were confirmed in vitro where extracellular VEGF in the cell culture medium was decreased significantly by tamoxifen treatment. Furthermore, we illustrate that microdialysis is a viable method that may be applied in human breast tissue to detect soluble VEGF in situ released by the tumor.
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PMID:Tamoxifen inhibits secretion of vascular endothelial growth factor in breast cancer in vivo. 1469 89

Vascular endothelial growth factor (VEGF) plays an important role in tumor angiogenesis, where it functions as one of the major angiogenic factors sustaining growth and draining catabolites. In this study, we developed an anti-VEGF ribozyme targeted to the 5' part of human VEGF mRNA. We endowed this ribozyme with an additional feature expected to improve its activity in vivo, by cloning it into a VAI transcriptional cassette. VAI is originally part of the adenovirus genome, and is characterized by high transcription rates, good stability due to its strong secondary structure and cytoplasmic localization. Transfection of U87 human glioblastoma cells with plasmid vectors encoding for this ribozyme resulted in a strong (-56%) reduction of VEGF secreted in the extracellular medium, indicating a good biological activity of the ribozyme. Moreover, this reduction in VEGF secretion had the important functional consequence of drastically diminishing the formation of tube-like structures of human umbilical vascular endothelial cells in a Matrigel in vitro angiogenesis assay. In conclusion, our VAI-embedded anti-VEGF ribozyme is a good inhibitor of angiogenesis in vitro, in a glioblastoma cell context. Thus, it may represent a useful tool for future applications in vivo, for antiangiogenic gene therapy of glioblastoma and of highly vascularized tumors.
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PMID:An anti-VEGF ribozyme embedded within the adenoviral VAI sequence inhibits glioblastoma cell angiogenic potential in vitro. 1508 86

Vascular endothelial growth factor (VEGF), which was originally discovered as vascular permeability factor, is critical to human cancer angiogenesis through its potent functions as a stimulator of endothelial cell survival, mitogenesis, migration, differentiation and self-assembly, as well as vascular permeability, immunosuppression and mobilization of endothelial progenitor cells from the bone marrow into the peripheral circulation. Genetic alterations and a chaotic tumor microenvironment, such as hypoxia, acidosis, free radicals, and cytokines, are clearly attributed to numerous abnormalities in the expression and signaling of VEGF and its receptors. These perturbations confer a tremendous survival and growth advantage to vascular endothelial cells as manifested by exuberant tumor angiogenesis and a consequent malignant phenotype. Understanding the regulatory mechanisms of both inducible and constitutive VEGF expression will be crucial in designing effective therapeutic strategies targeting VEGF to control tumor growth and metastasis. In this review, molecular regulation of VEGF expression in tumor cells is discussed.
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PMID:Constitutive and inducible expression and regulation of vascular endothelial growth factor. 1545 Feb 48

Vascular endothelial growth factor (VEGF) is an angiogenic cytokine, which plays a major role in tumor angiogenesis. VEGF mRNA expression is controlled by hypoxia, growth factors and hormones through both transcriptional and post-transcriptional mechanisms. VEGF mRNA has a short half-life and its abundance is regulated by the binding of stabilizing (HuR, hRNP-L) and still uncharacterised destabilizing proteins to its 3'-untranslated region. Here, we report that the ACTH-regulated zinc-finger protein TIS11b and its homologs TIS11 and TIS11d interact with the 3'-untranslated region of VEGF mRNA and decrease its stability (half-life reduced from 130 to 60 min). Within the 2201 bp 3'-untranslated region of VEGF mRNA, we identified a 75 bp domain, containing two consensus AU-rich motifs, which binds TIS11b and mediates its destabilizing activity. Ribonucleoprotein (RNP) complex immunoprecipitation experiments allowed us to demonstrate that the interaction between TIS11b and VEGF 3'-untranslated region occurs in live cells. Knocking down TIS11b expression in primary adrenocortical cells with small interfering (si)RNAs clearly indicated that TIS11b participates in the control of both basal and, to a larger extent, ACTH-induced VEGF mRNA expression levels. TIS11b is the first VEGF mRNA-destabilizing protein identified so far and therefore appears as a new potential target in antiangiogenic therapies.
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PMID:Destabilization of vascular endothelial growth factor mRNA by the zinc-finger protein TIS11b. 1546 55

Neoangiogenesis is assumed to play an important role in the progression, metastasis and prognosis of a wide variety of tumors. To get insights into the molecular-genetic pathways and the biological role of angiogenesis in urothelial carcinogenesis, we analyzed comparatively the expression of the mRNA of the vascular endothelial growth factor (VEGF) and of the angiopoietins-1 and -2 (Ang-1 and Ang-2) in 71 transitional cell carcinomas (TCC) of the urinary bladder in relation to the tumor grades and stages, and referring to epidemiological risk factors. Using real-time quantitative reverse transcription-polymerase chain reaction, low-stage superficial TCC expressed VEGF and Ang-2 mRNA at a significantly higher level than high-stage muscle invasive carcinomas, and low-grade TCC at an insignificantly higher level than high-grade tumors. The activity of both angiogenic factors was found to be significantly correlated. Conversely, Ang-1 mRNA was expressed at a 3-fold significantly lower level in low-grade, low-stage compared to high-grade, high-stage TCC. A significantly 3- and 2-fold respectively, drop of the VEGF and Ang-2 mRNA expression in conjunction with a 2-fold significantly higher expression of Ang-1 mRNA in the group of grade 2 TCC when infiltrating the muscle layer may represent a crucial event during urothelial carcinogenesis, and possibly indicates an important step in promoting the conversion of bladder cancer from a low to a high malignancy in this subset of carcinomas. By immunhistochemistry, high-grade, high-stage carcinomas less frequently displayed areas with a strong reactivity for the VEGF protein ('hot spots") than low-grade, low-stage TCC, paralleling the expression of the mRNA. The expression patterns observed are compatible with a reduced vascular destabilization and decreased formation of new blood vessels in advanced TCC, suggesting a balance between vessel regression and vascular growth, with a less pronounced vascular remodeling during late phases of urothelial carcinogenesis. Analyzing the effect of life-style bladder cancer risk factors, habitual smoking and coffee consumption was not observed to substantially alter the expression of the angiogenic mediators, except for weakly elevated levels of VEGF and Ang-2 mRNA in TCC of strong smokers and a borderline significantly decreased VEGF mRNA expression associated with heavy coffee consumption. Certain hazardous occupational exposures (polycyclic hydrocarbons, paints and lacquer, stone dust) may play a role in modulating tumor angiogenesis. The current data indicate that the signaling molecular-genetic pathways underlying vascular remodeling are involved in the progression of urinary bladder cancer to a more malignant and aggressive behaviour.
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PMID:Alteration of the vascular endothelial growth factor and angiopoietins-1 and -2 pathways in transitional cell carcinomas of the urinary bladder associated with tumor progression. 1551 81

Vascular endothelial growth factor (VEGF) and its receptors have been implicated as key factors in tumor angiogenesis that are up-regulated by hypoxia. We evaluated the effects of DNA-binding small molecules on hypoxia-inducible transcription of VEGF. A synthetic pyrrole-imidazole polyamide designed to bind the hypoxia response element (HRE) was found to disrupt hypoxia-inducible factor (HIF) binding to HRE. In cultured HeLa cells, this resulted in a reduction of VEGF mRNA and secreted protein levels. The observed effects were polyamide-specific and dose-dependent. Analysis of genome-wide effects of the HRE-specific polyamide revealed that a number of hypoxia-inducible genes were down-regulated. Pathway-based regulation of hypoxia-inducible gene expression with DNA-binding small molecules may represent a new approach for targeting angiogenesis.
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PMID:Inhibition of vascular endothelial growth factor with a sequence-specific hypoxia response element antagonist. 1555 99

The induction of proangiogenic cytokines such as vascular endothelial growth factor (VEGF) is a critical feature of tumor angiogenesis. In the present study, we examined the mechanisms of VEGF gene expression induced by glucose deprivation in cancer cells, a role of AMP-activated protein kinase (AMPK) in the process, and the signal transduction pathway. AMPK functions as an energy sensor to provide metabolic adaptation under ATP-depleting conditions such as hypoxia and nutritional deprivation. Here, we show that glucose deprivation leads to a significant increase in the mRNA level of VEGF, GLUT1, and PFKFB3 genes in several cancer cells via a hypoxia-inducible factor-1-independent mechanism, and we demonstrate an essential role of AMPK in these gene expressions. Our data suggest that VEGF mRNA induction by glucose deprivation is due to an increase in mRNA stability, and the AMPK activity is necessary and sufficient to confer the stability to VEGF mRNA. We further show that reactive oxygen species is involved in glucose deprivation-induced AMPK activity in DU145 human prostate carcinomas, and c-Jun amino-terminal kinase acts as an upstream component in AMPK activation cascades under these conditions. LKB1, which was recently identified as a direct upstream kinase of AMPK, was not detected in DU145 cells. In conclusion, our results demonstrate a novel and major role of AMPK in the post-transcriptional regulation of VEGF, further implying its potential role in tumor angiogenesis.
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PMID:Glucose deprivation increases mRNA stability of vascular endothelial growth factor through activation of AMP-activated protein kinase in DU145 prostate carcinoma. 3044 4

Interaction between cancer cells and adjacent stromal cells is important to promote tumor development. Our aim was to study total COX-2 mRNA expression in both cancer cells and surrounding stromal cells and its association with angiogenic factor VEGF mRNA expression, tumor angiogenesis and prognosis in patients with NSCLC. COX-2 mRNA expression in both cancer cells and stromal tissue was analyzed using real-time quantitative (RTQ) RT-PCR in 60 NSCLC surgical specimens. Immunohistochemistry (IHC) was used to localize COX-2 protein in tumor specimens. Correlations between tumoral total COX-2 mRNA expression and VEGF mRNA expression (measured by RTQ RT-PCR), intratumoral microvessel counts (evaluated by IHC), other clinicopathologic variables, survival and relapse were tested. COX-2 protein expression was found in cancer as well as the surrounding stromal cells (including infiltrating inflammatory cells and endothelial cells of tumor-associated microvessels). VEGF protein expression was mainly located in cancer cells. There was a significant association between high tumoral total COX-2 mRNA expression and high VEGF mRNA expression (p = 0.01) or high intratumoral MVC (p < 0.001) but not other clinicopathologic variables, including tumor status and lymph node metastasis. Patients with higher tumoral total COX-2 mRNA expression had a statistically shorter survival time (median 15.0 +/- 2.61 months) and relapse time (median 5.0 +/- 1.37 months) than those with lower tumoral total COX-2 mRNA expression (median 40.0 +/- 3.12 and 34.0 +/- 3.11 months; p < 0.0001 and p < 0.0001, respectively, log-rank test). A significant difference in survival and relapse time was also seen between patients with high and low tumoral VEGF mRNA expression and between those with high and low intratumoral MVC (p = 0.0046 and p = 0.0038, respectively). After stratification by disease stage or histologic subtype, the prognostic significance of high total COX-2 mRNA expression was still apparent in both stage I and stage II-IV and in both squamous cell carcinoma and adenocarcinoma (p < or = 0.01 for all). Multivariate analysis using the Cox regression model with backward elimination showed that tumoral total COX-2 mRNA expression and lymph node status were the 2 most important independent prognostic predictors for survival and disease relapse. We report that total COX-2 mRNA expression in cancer cells and surrounding stromal cells correlates strongly and positively with VEGF mRNA expression, intratumoral MVC and adverse prognosis in NSCLC patients. This implies that COX-2 expression in both cancer cells and stromal cells within the tumor microenvironment may play an important role in upregulating the expression of the angiogenic factor VEGF and tumor angiogenesis in NSCLC and explains, in part, the adverse prognostic effect of COX-2 overexpression in patients with NSCLC.
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PMID:Total cyclooxygenase-2 mRNA levels correlate with vascular endothelial growth factor mRNA levels, tumor angiogenesis and prognosis in non-small cell lung cancer patients. 1570 7

The lysosomal protease cathepsin B has been implicated in a variety of pathologies including pancreatitis, tumor angiogenesis, and neuronal diseases. We used a tube formation assay to investigate the role of cathepsin B in angiogenesis. When cultured between two layers of collagen I, primary endothelial cells formed tubes in response to exogenously added VEGF. Overexpressing cathepsin B reduced the VEGF-dependent tube response, whereas pharmacologically or molecularly suppressing cathepsin B eliminated the dependence on exogenous VEGF. However, tube formation still required VEGF receptor activity, which suggested that endothelial cells generated VEGF. Indeed, VEGF mRNA and protein was detectable in cells treated with cathepsin B inhibitor, which correlated with a rise in the level of HIF-1alpha. In addition to boosting the level of proangiogenic factors, blocking cathepsin B activity reduced the amount of the antiangiogenic protein endostatin. Thus endothelial cells have the intrinsic capacity to generate pro- and antiangiogenic agents. These observations complement and expand our appreciation of how endothelial cell-derived proteases regulate angiogenesis.
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PMID:Cathepsin B regulates the intrinsic angiogenic threshold of endothelial cells. 1590 32


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