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Results for “Endothelialization”

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At least 415 records · Page 23Linked to original sources

PubMed2004

Leptin stimulates ischemia-induced retinal neovascularization: possible role of vascular endothelial growth factor expressed in retinal endothelial cells.

Diabetic retinopathy is the leading cause of new blindness in adults in developed countries. Leptin, an adipocyte-derived hormone, stimulates endothelial proliferation and angiogenesis. This study was designed to elucidate the pathophysiologic role of leptin in the progression of retinal neovascularization. Using the retinopathy of prematurity model, a mouse model of ischemia-induced retinal neovascularization, we have demonstrated more pronounced retinal neovascularization in 17-day-old transgenic mice overexpressing leptin than in age-matched wild-type littermates. Ischemia-induced retinal neovascularization was markedly suppressed in 17-day-old leptin-deficient ob/ob mice. Western blot analysis revealed that a biologically active leptin receptor isoform is expressed in mouse retinal endothelial cells. Leptin receptor expression was also detected in primary cultures of porcine retinal endothelial cells, where it upregulated vascular endothelial growth factor (VEGF) mRNA expression. This effect was thought to be mediated at least partly through the activation of signal transducers and activators of transcription (STAT)3, because adenoviral transfection of the dominant-negative form of STAT3 abolished the leptin-induced upregulation of VEGF mRNA expression in retinal endothelial cells. This study provides evidence that leptin stimulates the ischemia-induced retinal neovasucularization possibly through the upregulation of endothelial VEGF, thereby suggesting that leptin antagonism may offer a novel therapeutic strategy to prevent or treat diabetic retinopathy.

Animals↗

PubMed2001

Multiple drug resistance phenotype of human endothelial cells induced by vascular endothelial growth factor 165.

AIM: To investigate the effect of vascular endothelial growth factor 165 (VEGF165) on sensitivity of endothelial cells to anticancer drugs. METHODS: Human dermal microvessel endothelial cells (HDMEC) were incubated with anticancer drugs in the presence of VEGF165. Survival of endothelial cells was assayed by MTT method. DNA fragments of apoptosis were detected by agarose electrophoresis. Potential mechanisms underlying the effect of VEGF165 on endothelial cells were investigated with RT-PCR and Western blot analysis. RESULTS: VEGF165 induced the multidrug resistance phenotype of HDMEC to a wide variety of anticancer drugs such as epirubicin, cisplatin, etoposide, mytomycin C, vincristine, CPT-11, and taxol in vitro. This protective effect was partly due to the up-regulation of lung drug resistance protein (LRP) and multidrug resistance-associated protein (MRP), as well as the down-regulation of Bax protein induced by VEGF165. CONCLUSION: VEGF165 induced multidrug resistance phenotype of endothelial cells, which implicated the anti-angiogenic effect of anticancer drugs might depend on microenvironment of tumors in vivo.

Angiogenesis Inhibitors↗

PubMed2003

Vascular endothelial growth factor (VEGF)-eluting stents: in vivo effects on thrombosis, endothelialization and intimal hyperplasia.

Local drug delivery by stent can reduce in-stent restenosis. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen. After stenting, the arterial wall is almost denuded of endothelium. This loss of endothelium contributes to the smooth muscle cell (SMC) proliferation seen in restenosis, since the endothelium actively inhibits SMC hyperplasia. Over time, the endothelium recovers and SMC hyperplasia is arrested. The capacity of VEGF-coated stents to accelerate re-endothelialization, and to therefore reduce restenosis and thrombosis, was tested in this study. Radiolabeled VEGF was absorbed onto stents and released over nine days in an in vitro perfusion circuit. VEGF-coated stents were deployed in arterial segments to study local tissue release. A New Zealand White rabbit iliac artery model for stent implantation was used. Re-endothelialization and thrombosis were assessed after seven days. Further animals were examined 28 days post-procedure for in-stent restenosis. Stented vessels were resin-embedded, sectioned and stained. Intimal thickening was calculated using computerized morphometry. In vitro, the stents released 80% of the initial load over nine days. At seven days, thrombus was significantly reduced (12.5 mg for controls versus 0 mg for VEGF; p = 0.014). No beneficial effect was seen on endothelialization, nor on intimal hyperplasia. Neointimal area was 2.2 0.9 mm2 for controls versus 2.4 1.8 mm2 for VEGF (p = 0.8). These VEGF-eluting stents do not accelerate re-endothelialization or inhibit restenosis. Stent thrombosis appears to be reduced, which may make these stents less thrombogenic and be valuable in higher-risk cases.

Animals↗

PubMed1998

Interaction of sickle erythrocytes with endothelial cells in the presence of endothelial cell conditioned medium induces oxidant stress leading to transendothelial migration of monocytes.

The abnormal adherence of sickle red blood cells (SS RBC) to endothelial cells has been thought to contribute to vascular occlusion, a major cause of morbidity in sickle cell disease (SCD). We determined whether the interaction of SS RBC with cultured endothelial cells induced cellular oxidant stress that would culminate in expression of cell adhesion molecules (CAMs) involved in the adhesion and diapedesis of monocytes and the adherence of SS reticulocytes. We showed that the interaction of SS RBC at 2% concentration in the presence of multimers of von Willebrand factor (vWf), derived from endothelial cell-derived conditioned medium (E-CM) with cultured human umbilical vein endothelial cells (HUVEC), resulted in a fivefold increased formation of thiobarbituric acid-reactive substances (TBARS) and activation of the transcription factor NF-kB, both indicators of cellular oxidant stress. Normal RBC show none of these phenomena. The oxidant stress-induced signaling resulted in an increased surface expression of a subset of CAMs, ICAM-1, E-selectin, and VCAM-1 in HUVEC. The addition of oxygen radical scavenger enzymes (catalase, superoxide dismutase) and antioxidant (probucol) inhibited these events. Additionally, preincubation of HUVEC with a synthetic peptide Arg-Gly-Asp (RGD) that prevents vWf-mediated adhesion of SS RBC reduced the surface expression of VCAM-1 and NF-kB activation. Furthermore, SS RBC-induced oxidant stress resulted in a twofold increase in the transendothelial migration of both monocyte-like HL-60 cells and human peripheral blood monocytes, and approximately a sixfold increase in platelet-endothelial cell adhesion molecule-1 (PECAM-1) phosphorylation, each of which was blocked by protein kinase C inhibitor and antioxidants. These results suggest that the adherence/contact of SS RBC to endothelial cells in large vessel can generate enhanced oxidant stress leading to increased adhesion and diapedesis of monocytes, as well as heightened adherence of SS reticulocytes, indicating that injury/activation of endothelium can contribute to vaso-occlusion in SCD.

Anemia, Sickle Cell↗

PubMed2005

Clinical significance of vascular endothelial growth factor-C and vascular endothelial growth factor receptor 3 in patients with T1 lung adenocarcinoma.

BACKGROUND: Vascular endothelial growth factor-C (VEGF-C) plays an important role in lymphangiogenesis and activates VEGF receptor-3 (VEGFR-3). Lymphatic spread is an important prognostic factor in patients with lung adenocarcinoma. The aim of the current study was to determine whether the expression of VEGF-C and VEGFR-3 correlates with clinicopathologic factors and prognosis in patients with TNM classification T1 lung adenocarcinoma. METHODS: The authors conducted a retrospective review of 129 consecutive patients who underwent complete resection for T1 lung adenocarcinoma. Immunohistochemical staining for VEGF-C, VEGF, VEGFR-3, CD34 (microvessels), tryptase (mast cells), and CD68 (macrophages) was performed to statistically analyze clinicopathologic implications of VEGF-C and VEGFR-3 status. RESULTS: Of 129 patients with T1 lung adenocarcinoma, 56 (43.3%) patients were positive for tumor-cell VEGF-C and 73 (56.6%) and 69 (53.5%) patients were positive for tumor-cell and endothelial-cell VEGFR-3, respectively. Patients with positive staining for tumor-cell VEGF-C showed significantly less favorable survival rates than patients with negative staining (P = 0.031). The survival rates of patients with positive staining for tumor-cell and endothelial-cell VEGFR-3 were significantly lower than those with negative staining (P = 0.0034 and P = 0.0020, respectively). Patients with positive staining for both tumor-cell VEGF-C and endothelial-cell VEGFR-3 exhibited the most unfavorable prognoses. Multivariate analysis demonstrated that coexpression of tumor-cell VEGF-C and endothelial-cell VEGFR-3 was an independent negative prognostic factor (P = 0.0129) as well as N factor (P = 0.0020). CONCLUSIONS: VEGF-C and VEGFR-3 status may be indicative of survival rates for patients with T1 lung adenocarcinoma.

Adenocarcinoma↗

PubMed2000

Effect of somatostatin and octreotide on proliferation and vascular endothelial growth factor secretion from murine endothelial cell line (HECa10) culture.

Angiogenesis, development of new blood vessels, is required for normal tissue repair and also for tumor cell proliferation, extracellular matrix invasion, and hematogenous metastases. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen that has been shown to play a key role in neovascularization. Inhibition of angiogenesis in vitro and in vivo was documented by administration of native neuropeptide somatostatin and its analog octreotide. We have studied the effect of somatostatin-14 (SRIF) and ocreotide (sandostatin) on proliferation activity and VEGF release from cultured murine endothelial cells HECa10 in vitro. SRIF in concentrations from 10(-9) to 10(-5) M and ocreotide in concentrations from 10(-9) to 10(-5) M diminished the proliferative activity of cultured cells vs controls. SRIF and ocreotide in concentrations from 10(-14) to 10(-6) M did not change the release of VEGF into supernatants of 24 or 72 h endothelial cell cultures. Although we showed the antiproliferative effect of SRIF and ocreotide on mouse endothelial cells, we were unable to demonstrate the inhibitory effect of tested peptides on VEGF secretion in vitro.

Animals↗

PubMed2006

The vascular endothelial growth factor VEGF165 induces perlecan synthesis via VEGF receptor-2 in cultured human brain microvascular endothelial cells.

A member of the vascular endothelial growth factor (VEGF) family, VEGF165, regulates vascular endothelial cell functions in autocrine and paracrine fashions in microvessels. Proteoglycans are highly glycosylated poly-anionic macromolecules that influence cellular behaviors such as proliferation and migration by interacting with cytokines/growth factors. In the present study, we investigated the regulation of proteoglycan synthesis by VEGF165 in cultured human brain microvascular endothelial cells. The cells were exposed to recombinant human VEGF165, and the proteoglycans were then characterized using biochemical techniques. VEGF165 treatment increased the accumulation of proteoglycans 1.4- and 1.6-fold in the cell layer and conditioned medium, respectively. This effect resulted from the activation of VEGFR-2, and was mimicked by vammin, a VEGFR-2 ligand from snake venom but not placenta growth factor, which binds specifically to VEGFR-1. VEGF165 stimulated the production and secretion of perlecan, substituted with shorter heparan sulfate side chains, but with unaltered sulfated disaccharide composition. The perlecan secreted by VEGF165-stimulated endothelial cells may be involved in the regulation of cellular behavior during angiogenesis, in diseases of the brain microvessels, and in the maintenance of the endothelial cell monolayer.

Brain↗

PubMed1997

Vascular endothelial growth factor and severity of nonproliferative diabetic retinopathy mediate retinal hemodynamics in vivo: a potential role for vascular endothelial growth factor in the progression of nonproliferative diabetic retinopathy.

PURPOSE: To determine the effect of vascular endothelial growth factor and retinopathy level on retinal hemodynamics in nondiabetic and diabetic rats and to evaluate retinal hemodynamics in nondiabetic and diabetic patients. METHODS: Forty-eight diabetic and 22 nondiabetic patients had their diabetic retinopathy levels determined from fundus photographs according to Early Treatment Diabetic Retinopathy Study (ETDRS). Fluorescein angiograms were recorded from the left eye by video fluorescein angiography. Retinal blood flow was calculated from the digitized angiograms. Human recombinant vascular endothelial growth factor or vehicle alone was injected intravitreally into 13 nondiabetic and 11 diabetic rats. RESULTS: Retinal blood flow decreased 33% in patients with ETDRS retinopathy level 10 compared with control patients (P = .001) and increased sequentially in more advanced stages of retinopathy, with a strong correlation between retinal blood flow and retinopathy level (r2 = 0.434, P = .001). In the diabetic rats, retinal blood flow was decreased 35.6% (P = .01). Vascular endothelial growth factor maximally increased retinal blood flow by 36.1% in nondiabetic rats after 25 minutes (P = .001) and by 73.7% in diabetic rats after only 5 minutes (P = .01) and caused a greater response in diabetic than in nondiabetic rats. CONCLUSIONS: Retinal blood flow increases with advancing nonproliferative diabetic retinopathy in humans, and diabetes accentuates the vascular endothelial growth factor-induced increase in retinal blood flow and venous dilation in rats. Vascular endothelial growth factor may contribute to the changes in retinal hemodynamics and morphology observed in early diabetic retinopathy.

Adult↗

PubMed1999

Vascular endothelial growth factor up-regulates nitric oxide synthase expression in endothelial cells.

OBJECTIVE: Vascular endothelial growth factor (VEGF), secreted by vascular cells and a variety of tumour cells, is a potent angiogenic factor. Since nitric oxide (NO) seems to play a key role in the VEGF-induced proliferation of endothelial cells, the aim of the present study was to determine whether VEGF stimulates endothelial NO synthase (eNOS) expression and hence results in a maintained increase in NO formation. METHODS: Experiments were performed using cultured human umbilical vein endothelial cells (HUVEC) and isolated rat aortic rings. eNOS expression was assessed by Western blotting and RT-PCR analysis. RESULTS: Exposure of either confluent HUVEC or rat aortic rings to VEGF165 significantly increased eNOS mRNA and protein levels. This stimulatory effect of VEGF165 on eNOS expression was associated with an elevation in the basal production of cGMP in HUVEC, and with a leftward shift of the concentration-relaxation curve to acetylcholine in aortic rings. The VEGF-induced increase in eNOS mRNA levels was abolished by tyrosine kinase inhibitors suggesting involvement of a tyrosine kinase-dependent pathway. Since eNOS mRNA levels remained elevated in VEGF-treated cells in the presence of actinomycin D. it is likely that the VEGF-induced up-regulation of eNOS expression may be a consequence of a post-transcriptional effect on eNOS mRNA stability. CONCLUSION: The results demonstrate that VEGF enhances the expression of eNOS in native and cultured endothelial cells, an effect which may be important in the process of VEGF-induced angiogenesis.

Analysis of Variance↗

PubMed1998

Intercellular communication between vascular smooth muscle and endothelial cells mediated by heparin-binding epidermal growth factor-like growth factor and vascular endothelial growth factor.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF), a potent mitogen and migration factor for vascular smooth muscle cells (SMC), promoted neovascularization in vivo in the rabbit cornea. MRI demonstrated quantitatively the angiogenic effect of HB-EGF when introduced subcutaneously into nude mice. HB-EGF is not directly mitogenic to endothelial cells but it induced the migration of bovine endothelial cells and release of endothelial cell mitogenic activity from bovine vascular SMC. This mitogenic activity was specifically blocked by neutralizing anti-vascular endothelial growth factor (VEGF) antibodies. In contrast, EGF or transforming growth factor-alpha (TGF-alpha) had almost no effect on release of endothelial mitogenicity from SMC. In addition, RT-PCR analysis demonstrated that VEGF165 mRNA levels were increased in vascular SMC 4-10-fold by 0.35-2 nM of HB-EGF, respectively. Our data suggest that HB-EGF, as a mediator of intercellular communication, may play a new important role in supporting wound healing, tumor progression and atherosclerosis by stimulating angiogenesis.

Animals↗

PubMed1998

Vascular endothelial growth factor upregulates constitutive cyclooxygenase 1 in primary bovine and human endothelial cells.

The effect of the angiogenic cytokine vascular endothelial growth factor (VEGF) on nitric oxide synthase (NOS) and cyclooxygenase (COX) expression was examined in human (HUVEC) and bovine (BAE) endothelial cells. VEGF (10 ng/ml) induced constitutive COX-1 expression in both HUVEC and BAE, but not the cytokine-inducible isoform, COX-2, inducible NOS or endothelial NOS. In HUVEC, VEGF (10 ng/ml) increased COX activity, but COX inhibitors had no effect on the proliferative response of endothelial cells to this cytokine. In conclusion the induction of COX-1 by VEGF is not involved in the mitogenic response of endothelial cells, but may be an important regulatory mechanism in the maintenance of vascular integrity.

Animals↗

PubMed2002

Co-expression of vascular endothelial growth factor and neuropilin-1 in ovine feto-placental artery endothelial cells.

Vascular endothelial growth factor (VEGF) is a key regulator for placental angiogenesis and vascular functions via activating two high affinity tyrosine-kinase receptors, VEGF receptor-1 (VEGFR-1) and -2 (VEGFR-2). Recently, a specific VEGF165 receptor, neuropilin-1 (NP-1), was also identified in endothelial cells and upon VEGF binding, NP-1, synergistically with VEGFR-2, enhances VEGF-induced cell proliferation and migration. To evaluate the role of VEGF and NP-1 in regulating fetoplacental angiogenesis and endothelial function, an ovine fetal placental artery endothelial (OFPAE) cell line was established. In this study, an OFPAE cell cDNA library was constructed. Two positive clones for VEGF and one for NP-1 were isolated from the OFPAE cell cDNA library, and their partial 3' sequences were identified. The sequence of VEGF cDNA insert had 98% homology to the reported ovine VEGF (GenBank accesssion # X89506). The partial NP-1 cDNA sequence included a portion of the protein coding region and a complete 3' untranslated region (UTR), and had 90% homology to human NP-1 (GenBank accession # AF016050). The predicted amino acid sequence of ovine NP-1 was 97-98% identical to human (GenBank accession # AAC12921.1), mouse (GenBank accession # NP_032763), and rat (GenBank accession # AAC53345.1) NP-1. Two CU-rich stabilizing and two consensus destabilizing elements 5'-AUUUA-3' were identified in the 3' UTR of ovine NP-1 cDNA sequence. These elements are the potential binding sites for mRNA-binding proteins which may regulate the stability of NP-1 mRNA. Expression of VEGF and NP-1 in OFPAE cells and fetal placentas was confirmed by Northern and Western blot analyses. Using PCR analysis, we also identified partial sequences of multiple VEGF isoforms (VEGF188, 183, 164, and 120) as well as VEGFR-1, VEGFR-2, and neuropilin-2 (NP-2) from the OFPAE cell cDNA library. These results indicate that multiple isoforms of VEGF are expressed in OFPAE cells. Moreover, we also identified, for the first time, a complete 3' UTR of NP-1 cDNA in any species. Together with expression of VEGF and VEGF receptors in OFPAE cells, we propose that there is an autocrine mechanism by which VEGF regulates fetal placental angiogenesis and other functions of endothelial cells.

Animals↗

PubMed1998

Upregulation of vascular endothelial growth factor by H2O2 in rat heart endothelial cells.

Hydrogen peroxide (H2O2) is a reactive oxygen species generated by several metabolic pathways in mammalian cells. Endothelial cells are extremely susceptible to oxidative stress. H2O2 has been reported to increase the permeability in these cells. Using rat heart endothelial cell culture as a model system, we examined the effect of H2O2 on the gene expression of vascular endothelial growth factor (VEGF), a potent mitogen of endothelial cells and a vascular permeability factor. By Northern blot analysis we found that VEGF mRNA responded to H2O2 in a dose-and time-dependent manner. The induction was superinduced by cycloheximide and blocked by actinomycin D. N-Acetylcysteine, a synthetic antioxidant, was able to suppress the induction. H7, a protein kinase C inhibitor, could also block the induction. Electrophoretic mobility shift assay revealed an enhanced binding of transcription factors, AP-1 and NF-kappaB. Immunoblot analysis showed that the amount of secreted VEGF was elevated in the medium 4 h after H2O2 stimulation. Our results demonstrate that VEGF gene expression is upregulated by H2O2 in these endothelial cells.

Acetylcysteine↗

PubMed2001

Src mediates stimulation by vascular endothelial growth factor of the phosphorylation of focal adhesion kinase at tyrosine 861, and migration and anti-apoptosis in endothelial cells.

Vascular endothelial growth factor (VEGF) stimulates the tyrosine phosphorylation of focal adhesion kinase (FAK), increases focal adhesion formation and is chemotactic for human umbilical-vein endothelial cells (HUVECs). In the present study we identified the major sites of VEGF-induced FAK tyrosine phosphorylation and investigated the mechanism mediating this pathway in the action of VEGF. VEGF increased the focal adhesion localization of FAK phosphorylated at Tyr-397 (Y397) and Y861 but stimulated a marked increase in phosphorylation at Y861 without significantly affecting the total level of phospho-Y397 FAK. Inhibition of Src with the specific inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) completely blocked VEGF-induced Y861 phosphorylation without decreasing the level of phospho-Y397 FAK. We also examined the role of Src in mediating endothelial functions of VEGF in which FAK has been implicated as having a role. PP2 markedly inhibited VEGF-induced chemotaxis and wound-healing cell migration. The Src inhibitor also decreased the anti-apoptotic effect of VEGF determined by surface staining of annexin V but did not increase FAK proteolysis or prevent the VEGF-dependent inhibition of FAK proteolysis. In contrast, the specific PtdIns 3-kinase inhibitor LY294002 induced apoptosis and markedly decreased p125(FAK) expression and increased FAK proteolysis but had little effect on Y861 phosphorylation. These findings identify Src-dependent FAK phosphorylation at Y861 as a novel VEGF-induced signalling pathway in endothelial cells and suggest that this pathway might be involved in the mechanisms mediating VEGF-induced endothelial cell migration and anti-apoptosis.

Apoptosis↗

PubMed2001

Characterization of endocrine gland-derived vascular endothelial growth factor signaling in adrenal cortex capillary endothelial cells.

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) has been recently identified as a mitogen specific for the endothelium of steroidogenic glands. Here we report a characterization of the signal transduction of EG-VEGF in a responsive cell type, bovine adrenal cortex-derived endothelial (ACE) cells. EG-VEGF led to a time- and dose-dependent phosphorylation of p44/42 MAPK. This effect was blocked by pretreatment with pertussis toxin, suggesting that G alpha(i) plays an important role in mediating EG-VEGF-induced activation of MAPK signaling. The inhibitor of p44/42 MAPK phosphorylation PD 98059 resulted in suppression of both proliferation and migration in response to EG-VEGF. EG-VEGF also increased the phosphorylation of Akt in a phosphatidylinositol 3-kinase-dependent manner. Consistent with such an effect, EG-VEGF was a potent survival factor for ACE cells. We also identified endothelial nitric-oxide synthase as one of the downstream targets of Akt activation. Phosphorylation of endothelial nitric-oxide synthase in ACE cells was stimulated by EG-VEGF with a time course correlated to the Akt phosphorylation. Our data demonstrate that EG-VEGF, possibly through binding to a G-protein coupled receptor, results in the activation of MAPK p44/42 and phosphatidylinositol 3-kinase signaling pathways, leading to proliferation, migration, and survival of responsive endothelial cells.

Adrenal Cortex↗

PubMed2002

Soluble egg antigens from Schistosoma mansoni induce angiogenesis-related processes by up-regulating vascular endothelial growth factor in human endothelial cells.

Schistosomiasis mansoni is characterized by hepatic granuloma formation. Endothelial cell activation within these granulomas may contribute to their development and to increased vascularization in the granuloma periphery. The earliest event in granuloma formation is the lodging of schistosome eggs within presinusoidal capillaries. The eggs secrete factors that may activate endothelial cells. This study investigated the effects of Schistosoma mansoni soluble egg antigen (SEA) on angiogenic processes: proliferation, tube formation, and apoptosis of human umbilical vein endothelial cells (HUVECs). HUVECs require serum and growth factors to proliferate in vitro. Proliferation occurred when SEA or live eggs were substituted for growth factors, but not for serum. SEA increased HUVEC tube formation and decreased HUVEC apoptosis after serum and growth factor deprivation. Messenger RNA for vascular endothelial growth factor (VEGF) increased 2-fold in SEA-treated HUVECs. These findings suggest that products secreted by schistosome eggs may promote angiogenesis within hepatic granulomas by up-regulating endothelial cell VEGF.

Animals↗

PubMed2001

Vascular endothelial growth factor induces manganese-superoxide dismutase expression in endothelial cells by a Rac1-regulated NADPH oxidase-dependent mechanism.

Vascular endothelial growth factor (VEGF) is a potent vascular endothelial cell-specific mitogen that modulates endothelial cell function. In the present study, we show that VEGF induces manganese-superoxide dismutase (MnSOD) mRNA and protein in human coronary artery endothelial cells (HCAEC) and pulmonary artery endothelial cells. VEGF-mediated induction of MnSOD mRNA was inhibited by pretreatment with the NADPH oxidase inhibitors, diphenyleneiodonium (DPI), and 4-(2-aminoethyl)-benzenesulfonyl fluoride, but not with the nitric oxide synthase inhibitor L-NAME (N-monomethyl-L-arginine) or the xanthine oxidase inhibitor allopurinol. VEGF stimulation of MnSOD was also inhibited by adenoviral-mediated overexpression of catalase Cu, Zn-SOD and a dominant-negative form of the small GTPase component of NADPH oxidase Rac1 (Rac1N17). Treatment of HCAEC with VEGF resulted in a transient increase in ROS production at 20 min, as measured by 2,7-dichlorodihydrofluorescein oxidation. This effect was abrogated by expression of Rac1N17. Taken together, these findings suggest that VEGF induces MnSOD by an NADPH oxidase-dependent mechanism and that VEGF signaling in the endothelium is coupled to the redox state of the cell.

Adenoviridae↗

PubMed2001

Vascular endothelial growth factor expression and tumor angiogenesis are regulated by androgens in hormone responsive human prostate carcinoma: evidence for androgen dependent destabilization of vascular endothelial growth factor transcripts.

PURPOSE: The hormonally regulated growth of some human carcinomas represents an important therapeutic target. We report that androgens modulate the angiogenic activity of hormone responsive human prostate cancer. MATERIALS AND METHODS: To define further the critical mechanisms underlying hormone responsiveness we examined the angiogenic mediator, vascular endothelial growth factor messenger (m) RNA and protein in response to androgens in vitro as well as the angiogenic response of xenografts of human prostate cancer after androgen withdrawal in vivo. RESULTS: In vitro androgen deprivation of LnCaP prostate cancer cells led to decreased vascular endothelial growth factor mRNA and protein expression as well as a 5-fold destabilization in vascular endothelial growth factor mRNA transcripts. In addition, androgen withdrawal inhibited the hypoxic induction of vascular endothelial growth factor mRNA. In mice bearing LnCaP tumors castration resulted in a rapid decrease in mRNA expression and markedly reduced tumor neovascularization. CONCLUSIONS: These findings implicate sex steroids as an important stimulus for vascular endothelial growth factor regulation in hormone sensitive tumors and demonstrate the reversal of neovascularization after hormone withdrawal as an early event in the tumor response to therapy.

Androgens↗