Endothelial Mitogen Research Articles

Use of Vascular Assessments and Novel Biomarkers to Predict Cardiovascular Events in Type 2 Diabetes: The SUMMIT VIP Study.

Cardiovascular disease (CVD) risk prediction represents an increasing clinical challenge in the treatment of diabetes. We used a panel of vascular imaging, functional assessments, and biomarkers reflecting different disease mechanisms to identify clinically useful markers of risk for cardiovascular (CV) events in subjects with type 2 diabetes (T2D) with or without manifest CVD. The study cohort consisted of 936 subjects with T2D recruited at four European centers. Carotid intima-media thickness and plaque area, ankle-brachial pressure index, arterial stiffness, endothelial function, and circulating biomarkers were analyzed at baseline, and CV events were monitored during a 3-year follow-up period. The CV event rate in subjects with T2D was higher in those with (n = 440) than in those without (n = 496) manifest CVD at baseline (5.53 vs. 2.15/100 life-years, P < 0.0001). New CV events in subjects with T2D with manifest CVD were associated with higher baseline levels of inflammatory biomarkers (interleukin 6, chemokine ligand 3, pentraxin 3, and hs-CRP) and endothelial mitogens (hepatocyte growth factor and vascular endothelial growth factor A), whereas CV events in subjects with T2D without manifest CVD were associated with more severe baseline atherosclerosis (median carotid plaque area 30.4 mm2 [16.1-92.2] vs. 19.5 mm2 [9.5-40.5], P = 0.01). Conventional risk factors, as well as measurements of arterial stiffness and endothelial reactivity, were not associated with CV events. Our observations demonstrate that markers of inflammation and endothelial stress reflect CV risk in subjects with T2D with manifest CVD, whereas the risk for CV events in subjects with T2D without manifest CVD is primarily related to the severity of atherosclerosis.

Angiogenesis and Vascular Remodeling in Chronic Airway Diseases

Asthma and chronic obstructive pulmonary disease remain a global health problem, with increasing morbidity and mortality. Despite differences in the causal agents, both diseases exhibit various degrees of inflammatory changes, structural alterations of the airways leading to airflow limitation. The existence of transient disease phenotypes which overlap both diseases and which progressively decline the lung function has complicated the search for an effective therapy. Important characteristics of chronic airway diseases include airway and vascular remodeling, of which the molecular mechanisms are complex and poorly understood. Recently, we and others have shown that airway smooth muscle (ASM) cells are not only structural and contractile components of airways, rather they bear capabilities of producing large number of pro-inflammatory and mitogenic factors. Increase in size and number of blood vessels both inside and outside the smooth muscle layer as well as hyperemia of bronchial vasculature are contributing factors in airway wall remodeling in patients with chronic airway diseases, proposing for the ongoing mechanisms like angiogenesis and vascular dilatation. We believe that vascular changes directly add to the airway narrowing and hyper-responsiveness by exudation and transudation of proinflammatory mediators, cytokines and growth factors; facilitating trafficking of inflammatory cells; causing oedema of the airway wall and promoting ASM accumulation. One of the key regulators of angiogenesis, vascular endothelial growth factor in concerted action with other endothelial mitogens play pivotal role in regulating bronchial angiogenesis. In this review article we address recent advances in pulmonary angiogenesis and remodelling that contribute in the pathogenesis of chronic airway diseases.

Essential Role for Endocytosis in the Growth Factor-stimulated Activation of ERK1/2 in Endothelial Cells

Vascular endothelial growth factor (VEGF) stimulates angiogenesis by binding to VEGF receptor 2 (VEGFR2) on endothelial cells (ECs). Downstream activation of the extracellular related kinases 1/2 (ERK1/2) is important for angiogenesis to proceed. Receptor internalization has been implicated in VEGFR2 signaling, but its role in the activation of ERK1/2 is unclear. To explore this question we utilized pitstop and dynasore, two small molecule inhibitors of endocytosis. First, we confirmed that both inhibitors block the internalization of VEGFR2 in ECs. We then stimulated ECs with VEGF in the presence and absence of the inhibitors and examined VEGFR2 signaling to ERK1/2. Activation of VEGFR2 and C-Raf still occurred in the presence of the inhibitors, whereas the activation of MEK1/2 and ERK1/2 was abrogated. Therefore, although internalization is not required for activation of either VEGFR2 or C-Raf in ECs stimulated with VEGF, internalization is necessary to activate the more distal kinases in the cascade. Importantly, inhibition of internalization also prevented activation of ERK1/2 when ECs were stimulated with other pro-angiogenic growth factors, namely fibroblast growth factor 2 and hepatocyte growth factor. In contrast, the same inhibitors did not block ERK1/2 activation in fibroblasts or cancer cells stimulated with growth factors. Finally, we show that these small molecule inhibitors of endocytosis block angiogenesis in vitro and in vivo. Therefore, receptor internalization may be a generic requirement for pro-angiogenic growth factors to activate ERK1/2 signaling in human ECs, and targeting receptor trafficking may present a therapeutic opportunity to block tumor angiogenesis.

Association of single nucleotide polymorphisms in vascular endothelial growth factor gene with bladder cancer risk

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific potent mitogen involved in a number of pathologic processes, including angiogenesis, tumor growth, and metastasis. Polymorphisms of VEGF gene have been associated with susceptibility to several cancers. VEGF gene susceptibility to bladder cancer (BC), however, still remains controversial. We analyzed association of the -2578C/A, -7C/T, -2549I/D, and -1001G/C polymorphism of the VEGF gene with bladder cancer (BC) risk and interaction of these polymorphisms with lifestyle and demographic factors. We genotyped -2578C/A, -7C/T, -2549I/D and -1001G/C by PCR-restriction fragment length polymorphism and amplification refractory mutation specific method to evaluate risk in 200 BC patients and 250 healthy controls from North Indian population. Significant association for BC risk in heterozygous CA genotype (1.69-fold) in VEGF-2578C/A and heterozygous genotype of VEGF-1001G/C (p = 0.032) was observed. Interestingly, VEGF-2549I/D genotype showed reduced risk for BC. The gene-gene combination analysis revealed DD-GG with reduced risk (p = 0.018) of VEGF-2549I/D and VEGF-1001G/C, and combination CA-GG of VEGF-2578C/A and VEGF-1001G/C demonstrated 1.75-fold risk for BC. Our findings suggested that polymorphism -2578C/A and -1001G/C in the promoter of VEGF gene may play a significant role in mediating the bladder cancer risk, whereas VEGF-2549I/D genotype appears to be protective for BC.

Vascular endothelial growth factor expression in ovarian serous carcinomas and its effect on tumor proliferation

Introduction:Vascular endothelial growth factor (VEGF), an endothelial mitogen, acts through VEGF receptors (VEGFRs) on the endothelial cells. During neoplastic transformation, it is hypothesized that the tumor expresses VEGF and also acquire VEGF receptor, enabling VEGF action in an autocrine and paracrine manner with varied effects on the tumor growth and progression. This study on ovarian serous carcinomas (OSCs) was done to determine the expression of VEGF and to correlate it with tumor proliferation.Material and Methods:Forty cases of OSCs were included. Immunohistochemistry was performed for VEGF and Ki-67. The VEGF slides were assigned an immunohistochemical score based on the staining intensity (a) and the percentage of tumor cells staining (b). The sum of both (a) and (b) ranged from 0-6. VEGF was considered positive when the score was more than 2. For Ki-67, maximally immunostained areas were selected; 500 cells counted and positive fraction determined. Mann Whitney test was used to determine the difference in the median value of Ki-67 between VEGF positive tumors and VEGF negative tumors.Results:Of the 40 cases, 32 cases had a VEGF score of >2 (positive) and 8 cases had VEGF score <2 (negative). The Ki-67 score ranged from 2-98%, with mean of 51%. The median Ki-67 index was much higher in VEGF positive cases as compared to VEGF negative tumors (57.5% vs. 40%). However, the difference in the two categories did not reach statistical significance (P = 0.45, Mann Whitney test).Conclusion:Ovarian serous carcinomas express VEGF in a significant number of cases (80% in the present study) although its potential mitogenic effect on tumor cells was not confirmed.

Critical Role of VEGF-C/VEGFR-3 Signaling in Innate and Adaptive Immune Responses in Experimental Obliterative Bronchiolitis

Chronic inflammation, a hallmark of obliterative bronchiolitis, is known to induce lymphangiogenesis. We therefore studied the role of lymphangiogenic vascular endothelial growth factor C (VEGF-C), its receptor VEGFR-3, and lymphangiogenesis during development of experimental obliterative bronchiolitis [ie, obliterative airway disease (OAD)] in rat tracheal allografts. The functional importance of VEGF-C was investigated by adenovirus-mediated overexpression of VEGF-C (AdVEGF-C), and by inhibition of VEGF-C activity with VEGFR-3-Ig (AdVEGFR-3-Ig). Analyses included histology, immunohistochemistry, and real-time RT-PCR 10 and 30 days after transplantation. In the course of OAD development, lymphangiogenesis was induced in the airway wall during the alloimmune response, which was reversed by cyclosporine A in a dose-dependent fashion. VEGF-C overexpression in tracheal allografts induced epithelial activation, neutrophil chemotaxis, and a shift toward a Th17 adaptive immune response, followed by enhanced lymphangiogenesis and the development of OAD. In contrast, inhibition of VEGF-C activity with VEGFR-3-Ig inhibited lymphangiogenesis and angiogenesis and reduced infiltration of CD4(+) T cells and the development of OAD. Lymphangiogenesis was linked to T-cell responses during the development of OAD, and VEGF-C/VEGFR-3 signaling modulated innate and adaptive immune responses in the development of OAD in rat tracheal allografts. Our results thus suggest VEGFR-3-signaling as a novel strategy to regulate T-cell responses in the development of obliterative bronchiolitis after lung transplantation.

Effect of exercise on HIF-1 and VEGF signaling

This review summarizes the literature describing the significance of various conditions, such as hypoxia, oxidative stress, and, above all, physical exercise, in the hypoxia-inducible factor-1 (HIF-1) and vascular endothelial growth factor (VEGF) signaling pathway mainly in skeletal muscle. HIF-1α acts as a master regulator for the expression of genes involved in the hypoxia response of most mammalian cells. Namely, HIF-1α initiates transcription of various hypoxia-adaptive genes, such as angiogenesis, glycolysis, and erythropoiesis, after the formation of heterodimer with HIF-1β. Among them, VEGF is the most potent endothelial specific mitogen, which recruits endothelial cells into hypoxic foci and avascular area and stimulates their proliferation. The study on acute exercise shows that several components of the HIF-1 pathway, involving VEGF and erythropoietin, are activated in response to acute changes in oxygen demand in human skeletal muscle, suggesting that oxygen sensitive pathways could be relevant for adaptaion to physical activity by increasing capillary growth. Also, the effects of endurance training on the activity of the HIF pathway in human skeletal muscle under hypoxic conditions appear to be definitely higher than those under normoxic conditions, indicating that combining hypoxia with exercise training appears to improve some aspects of muscle O2 transport and/or metabolism. On the other hand, increased levels of reactive oxygen species (ROS) due to physical exercise induce the expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), which regulates mitochondrial biogenesis in multiple cell types, resulting in increases in VEGF expression and subsequent angiogenesis, strongly suggesting HIF-1α-independent regulation of VEGF and angiogenesis. Thus, the precise relationship among exercise, the HIF-1 pathway including VEGF, PGC-1α, and ROS needs further study.

Experimentally induced puromycine aminonucleoside nephrosis (PAN) in rats: evaluation of angiogenic protein platelet-derived endothelial cell growth factor (PD-ECGF) expression in glomeruli.

BackgroundIn experimentally induced puromycine aminonucleoside nephrosis (PAN) animal models, nephrotic syndrome with minimal change disease and focal and segmental sclerosis-like nephritis similar to that in human is demonstrated; however, the real mechanism of PAN is not yet elucidated. Platelet derived endothelial cell growth factor (PD-ECGF), an endothelial mitogen protein, is believed to take part in microvessel formation and in stimulation of angiogenesis and its expression has not been totally demonstrated in PAN rats yet. In this study, we aimed to examine PD-ECGF expression in acute and chronic PAN induced in rats and find out the association between its expression and the stages of angiogenesis in kidney.MethodsFor the experiment, twenty-four Male Wistar Albino rats were used and divided into four groups; control group (n = 6), pre-proteinuria group (n = 6), acute group (n = 6) and chronic group (n = 6). We compared statistically all data by One-way ANOVA Test followed by Dunn Multiple Comparison Test.ResultsProteinurea levels in control and pre-proteinuria groups were not statistically different; however, it was remarkably higher in the acute nephrosis group and significantly greater in the chronic nephrosis group than control group (p < 0.0025). In pre-proteinuria group, the serum albumin and creatinine clearances also did not significantly differ from the control group. On the other hand, in the acute and chronic nephrosis groups, serum albumin and creatinine clearances progressively decreased (p < 0.05). In our immunohistochemical studies, we showed elevated PD-ECGF expression in glomeruli of acute and chronic PAN rats. Microscopic and ultrastructural appearances of the glomeruli of acute and chronic PAN showed various sequential steps of angiogenesis, macrophages and immature capillaries with primitive lumens and apoptotic endothelial cells in the increased mesangial matrix.ConclusionsIt is reported that acute and chronic PAN progressively increase PD-ECGF expression and following induction of angiogenesis in the affected glomeruli.

Plasma Brain Derived Neurotropic Factor and Platelet Derived Growth Factor Levels Are Elevated in Children with Sickle Cell Anemia and Abnormal Transcranial Doppler and/or Stroke

Abstract 516Children with sickle cell anemia (SCA) are at increased risk for stroke due to abnormal cerebral blood flow (CBF). The Stroke Prevention (STOP I) study showed that abnormal CBF could be detected using Trans-cranial Doppler (TCD), and may predict the risk for stroke. High TCD may be an indicator of main or branch cerebral artery vascular dysfunction, stenosis or fibrosis. Abnormal CBF is associated with cerebral ischemia and ultimately stroke. Brain derived neurotropic factor (BDNF) is a nerve growth factor with anti-apoptotic and neuro-protective properties. It is released in the central nervous system in response to ischemia. Platelet derived growth factor (PDGF) is an endothelial and smooth muscle mitogen. We hypothesized that circulating BDNF and PDGF levels will be elevated and may be associated with abnormal CBF as indicated by high TCD velocity measurements.Three groups of children, i.e. 1) SCA with abnormal TCDs (SATCD) - abnormal TCD ≥200 cm/sec, 2) SCA with normal TCDs (SNTCD) -normal TCD ≤170 cm/sec and 3) healthy controls were investigated. Stored, baseline plasma samples from the Stroke Prevention (STOP I) study and from an ongoing study of nutritional effects on inflammation in SCA children (NUTSCD) were analyzed in duplicate, using a multiplex antibody immobilized bead assay. Plasma levels of BDNF, PDGF AA and AB/BB and 10 other pro- and anti-inflammatory cytokines were assessed. A total of 39 samples (11 SATCD, 21 SNTCD and 7 controls) were analyzed. Of the 11 SATCD, 8 were eventually randomized to the standard care (SC), while 3 were in the transfusion (Tx) arm of STOP I. Since some of the SCA patients subsequently developed stroke, the levels of BDNF and PDGF in those who did vs. did not develop stroke were compared. Except where not applicable, values are presented as mean±SD. Chi-square was used to access distribution, while means were compared using t-test and analysis of variance (ANOVA). A Receiver Operator Characteristic (ROC) curve was used to access the sensitivity of BDNF and PDGF in predicting abnormal CBF as indicated by abnormal TCD measurement.The TCD velocity for SATCD group was 250±32 cm/s. There was no statistically significant difference in age or gender distribution among the groups. The mean body mass index was significantly lower for SCA subjects compared with controls (15±1kg/m2 vs. 23±7 kg/m2, p= 0.026). There was a statistically significant difference in mean BDNF levels, which was highest in SATCD compared with SNTCD (234±53 vs. 166±110 pg/ml, p=0.036) and controls (34±20 pg/ml, p<0.001). Difference in the BDNF levels between SNTCD and controls was also statistically significant, p=0.006. PDGF AA levels were significantly higher in SATCD compared with SNTCD (356±147pg/ml vs. 227±156 pg/ml, p = 0.045) and controls (34±32pg/ml, p<0.001). Also, PDGF AA levels were significantly higher for SNTCD vs. controls (p = 0.014). Six of the 7 patients who developed stroke had abnormal TCD, while one had conditional TCD (186cm/s, F, 3yo). However, all SCA patients who subsequently developed stroke had significantly higher PDGF AA levels than those who did not (350±180pg/ml vs. 249±154pg/ml, p=0.039). The BDNF levels, were not significantly different for SCA who subsequently developed stroke vs. those who did not (201±69pg/ml vs. 186±106pg/ml). Of the 3 patients receiving Tx, one who eventually had stroke, had very high (pre-Tx) PDGF AA level (312pg/ml); almost as high as those on SC who developed stroke (358±197pg/ml, n=6), and higher than the remaining 2 Tx patients who did not develop stroke (233±0.5pg/ml). The ROC curve showed that both BDNF and PDGF were sensitive (AUC=0.8, p<0.05) predictors of abnormal CBF as indicated by high TCDs velocity measurement.High TCD velocity in children with SCA was associated with elevated BDNF and PDGF AA levels. Moreover, PDGF AA levels were significantly higher in the SCA patients who developed stroke. Further study is warranted to determine whether BDNF and/or PDFG AA, alone or with abnormal TCD, will better predict future stroke risk. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

The Evaluation of Basic Fibroblast Growth Factor and Fibroblastic Growth Factor Receptor 1 Levels in Saliva and Serum of Patients with Salivary Gland Tumor

Basic fibroblast growth factor (FGF2) is a well-known endothelial mitogen that regulates endothelial cell proliferation, migration, differentiation, and survival. In the present study, we investigated the levels of FGF2 and fibroblastic growth factor receptor 1 (FGFR1) in saliva and serum of patients with salivary gland tumors. Saliva and serum samples were collected from 43 patients with salivary gland tumors and 40 healthy volunteers. The FGF2 and FGFR1 concentrations in saliva and serum samples were measured by enzyme-linked immunosorbent assay. We found that the levels of FGF2 and FGFR1 in saliva and serum from patients with salivary gland tumors were significantly higher than those from healthy control subjects. These results suggest that salivary FGF2 and FGFR1 can be used as potential biomarkers in the diagnosis of salivary gland tumors.

Potential role of follicle‐stimulating hormone (FSH) and transforming growth factor (TGFβ1) in the regulation of ovarian angiogenesis

Angiogenesis occurs during ovarian follicle development and luteinization. Pituitary secreted FSH was reported to stimulate the expression of endothelial mitogen VEGF in granulosa cells. And, intraovarian cytokine transforming growth factor (TGF)β1 is known to facilitate FSH-induced differentiation of ovarian granulosa cells. This intrigues us to investigate the potential role of FSH and TGFβ1 regulation of granulosa cell function in relation to ovarian angiogenesis. Granulosa cells were isolated from gonadotropin-primed immature rats and treated once with FSH and/or TGFβ1 for 48 h, and the angiogenic potential of conditioned media (granulosa cell culture conditioned media; GCCM) was determined using an in vitro assay with aortic ring embedded in collagen gel and immunoblotting. FSH and TGFβ1 increased the secreted angiogenic activity in granulosa cells (FSH + TGFβ1 > FSH ≈ TGFβ1 >control) that was partly attributed to the increased secretion of pro-angiogenic factors VEGF and PDGF-B. This is further supported by the evidence that pre-treatment with inhibitor of VEGF receptor-2 (Ki8751) or PDGF receptor (AG1296) throughout or only during the first 2-day aortic ring culture period suppressed microvessel growth in GCCM-treated groups, and also inhibited the FSH + TGFβ1-GCCM-stimulated release of matrix remodeling-associated gelatinase activities. Interestingly, pre-treatment of AG1296 at late stage suppressed GCCM-induced microvessel growth and stability with demise of endothelial and mural cells. Together, we provide original findings that both FSH and TGFβ1 increased the secretion of VEGF and PDGF-B, and that in turn up-regulated the angiogenic activity in rat ovarian granulosa cells. This implicates that FSH and TGFβ1 play important roles in regulation of ovarian angiogenesis during follicle development.

Overexpression of netrin-1 improves neurological outcomes in mice following transient middle cerebral artery occlusion

Netrin-1 (NT-1) is one of the axon-guiding molecules that are critical for neuronal development. Because of its structural homology to the endothelial mitogens, NT-1 may have similar effects on vascular network formation. NT-1 was shown to be able to stimulate the proliferation and migration of human cerebral endothelial cells in vitro and also promote focal neovascularization in adult brain in vivo. In the present study, we reported the delivery of NT-1 using an adeno-associated virus (AAV) vector (AAV-NT-1) into mouse brain followed by transient middle cerebral artery occlusion (tMCAO). We found that AAV vectors did not elicit a detectable inflammatory response, cell loss or neuronal damage after brain transduction. The level of NT-1 was increased in the AAV-NT-1-transduced tMCAO mice compared with the control mice. Furthermore, the neurobehavioral outcomes were significantly improved in AAV-NT-1-transduced mice compared with the control animals (P<0.05) 7 days after tMCAO. Our data suggests that NT-1 plays a neuronal function recovery role in ischemic brain and that NT-1 gene transfer might present a valuable approach to treat brain ischemic disorders.

Vasopressin induces human mesangial cell growth via induction of vascular endothelial growth factor secretion

Vasoactive hormones, growth factors, and cytokines are important in promoting mesangial cell growth, a characteristic feature of many glomerular diseases. Vascular endothelial growth factor (VEGF) is an endothelial mitogen and promoter of vascular permeability that is constitutively expressed in human glomeruli, but its role in the kidney is still unclear. In the present study, we investigated the ability of vasopressin (AVP) to stimulate VEGF secretion by and correlation with AVP-induced cell growth in human mesangial cells. AVP caused time- and concentration-dependent increases in VEGF secretion from human mesangial cells, which was in turn potently inhibited by a V(1A) receptor-selective antagonist, confirming that this secretion is a V(1A) receptor-mediated event. VEGF also induced mesangial cell growth which was completely inhibited on administration of an anti-VEGF neutralizing antibody. Further, AVP-induced mesangial cell growth was completely abolished by the V(1A) receptor-selective antagonist and partially inhibited by an anti-VEGF neutralizing antibody. These results suggest that AVP stimulates VEGF secretion by human mesangial cells via V(1A) receptors. This secreted VEGF may function as an autocrine hormone to regulate mesangial cell growth, a mechanism by which AVP might contribute to progressive glomerular diseases such as diabetic nephropathy.

Abstract A4: Phase I clinical trial evaluating the safety, pharmacokinetics and biological effect of intravenous bevacizumab (avastin) in combination with escalating doses of AZD2171 (cediranib) administered orally for 21 consecutive days to patients with advanced malignancies (NCI protocol #7534)

Abstract Background: Angiogenesis inhibitors may be classified as direct or indirect inhibitors. Direct inhibitors like bevacizumab (B) that target the microvascular endothelial cells and prevent them from responding to different endothelial mitogens. Conversely, indirect inhibitors like cediranib (C), target growth-factor tyrosine kinases and its VEGF receptors on tumor endothelium. We hypothesized that maximizing VEGF inhibition with a combination therapy consisting of a direct angiogenesis inhibitor (B) and an indirect inhibitor (C) with different VEGF blocking mechanisms may result in increased anti-tumor activity and a safe toxicity profile. As a first step, we conducted a phase I study of the combination of bevacizumab and cediranib in advanced cancer patients. Methods: Pts with advanced solid tumors refractory to standard therapy were eligible. The trial is a conventional phase I 3+3 dose-escalation design. Cediranib was administered orally continuously for 21 days. Bevacizumab was given every two weeks (days 1 and 15) at escalating doses. Correlative studies including pharmacokinetic studies of cediranib, DCE-MRI, and circulating tumor (CTCs) and endothelial cells (CECs). Results: A total of 27 pts have been treated. Dose level 3 (C-30 mg/day and B-5mg/kg/2 weeks) was determined to be the MTD with the major dose-limiting toxicity of hypertension. The most common drug related toxicities include hypertension (66%), fatigue (41%), and anorexia (33%). Currently, of the 17 evaluable pts by RECIST, 7 pts had SD for &amp;gt;4 cycles (months). One confirmed PR was noted in a metastatic basal cell carcinoma pt (−33%) and one unconfirmed PR (−31%) in ovarian cancer pt. Several notable minor responses by RECIST have also been observed in the SD pts; 2 pts with RCC (−21%, −23%), an alveolar soft tissue sarcoma pt (−24%), and a prostate cancer pt (−21%). Overall, immature CECs (CD105+) enumerated by CellSearch™ revealed a dose-dependent significant decrease (1,290% to 93%; p=0.0001). A 3-fold induction in apoptosis was observed at 24 hrs compared to baseline in the CD105-positive CECs. Overall, mature CECs (CD31+) assessed for VEGFR2 activity revealed an 83% and 1.9% significant (p=0.019) inhibition in pVEGFR2 expression at low (B;3mg/kg) and high (B;5mg/kg) doses, respectively. In the non-responders, mature CECs revealed a dose-dependent (C;20mg/kg–30mg/kg) significant increase (−6.8% to 63%;p=0.031) in pERK/ERK expression levels. PK and DCE-MRI analysis is pending. Conclusions: The MTD was determined to be cediranib 30mg/day and bevacizumab 5mg/kg/2weeks. Activity has been seen in a diverse number of tumor types. Inhibition of pVEGFR2 and induction of apoptosis in CECs shows target effect by the combination. Grant support: National Cancer Institute grant and 2 UO1 CA062461-15 Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A4.

Netrin-1 prevents ischemia/reperfusion-induced myocardial infarction via a DCC/ERK1/2/eNOSs1177/NO/DCC feed-forward mechanism

We have recently shown that a novel endothelial mitogen netrin-1 potently stimulates nitric oxide (NO) production via a DCC-ERK1/2 dependent mechanism. In view of the well-established cardioprotective role of NO, the present study investigated whether netrin-1 is cardioprotective via NO signaling in the heart. Netrin-1 receptor DCC was abundantly expressed in the C57BL/6J mouse hearts. Perfusion of heart with netrin-1 (100 ng/mL) using a Langendorff system significantly increased NO production. Under ischemia/reperfusion (I/R), netrin-1 induced a substantial reduction in infarct size (21.8±4.9% from 42.5±3.6% in the controls), which was accompanied by an augmented production of NO. Pre-perfusion with DCC-antibody, U0126 (MEK1/2 inhibitor), L-NAME or PTIO (NO scavenger) attenuated protective effects of netrin-1 on infarct size and NO production, indicating upstream roles of DCC and ERK1/2 in NO production, as well as an essential role of NO in cardioprotection. Netrin-1 induced reduction in infarct size was significantly attenuated in DCC+/− mice, confirming an intermediate role of DCC. In additional experiments we found netrin-1 increased ERK1/2 and eNOSs1177 phosphorylation, and DCC protein expression, which was diminished by I/R. Furthermore, netrin-1-induced DCC upregulation was NO and ERK1/2-dependent, implicating a feed-forward mechanism. DAF-AM staining revealed enhanced NO production in both cardiac endothelial cells (ECs) and myocytes. In primarily isolated cardiomyocytes, netrin-1 also increased NO production, DCC abundance and ERK1/2 phosphorylation. Of note, cardiac apoptosis was significantly attenuated by netrin-1, which was reversed by DCC-antibody, U0126, L-NAME or PTIO. In summary, our data clearly demonstrate that netrin-1 potently protects the heart from I/R injury by stimulating NO production from cardiac ECs and myocytes. This potent effect is mediated by a DCC/ERK1/2/eNOSs1177/NO/DCC feed-forward mechanism in both cell types.

Osteoblasts stimulated with pulsed electromagnetic fields increase HUVEC proliferation via a VEGF‐A independent mechanism

The clinically beneficial effect of low frequency pulsed electromagnetic fields (ELF-PEMF) on bone healing has been described, but the exact mechanism of action remains unclear. A recent study suggests that there is a direct autocrine mitogenic effect of ELF-PEMF on angiogenesis. The hypothesis of this study is that ELF-PEMF also has an indirect effect on angiogenesis by manipulation of vascular endothelial growth factor (VEGF)-A-based paracrine intercellular communication with neighboring osteoblasts. Conditioned media experiments measured fetal rat calvarial cell (FRC) and human umbilical vein endothelial cell (HUVEC) proliferation using tritiated thymidine uptake. We demonstrate that ELF-PEMF (15 Hz, 1.8 mT, for 8 h) has an indirect effect on the proliferation rate of both endothelial cells and osteoblasts in vitro by altering paracrine mediators. Conditioned media from osteoblast cells stimulated with ELF-PEMF increased endothelial proliferation 54-fold, whereas media from endothelial cells stimulated with ELF-PEMF did not affect osteoblast proliferation. We examined the role of the pro-angiogenic mediator VEGF-A in the mitogenic effect of ELF-PEMF-stimulated osteoblast media on endothelial cells. The production of VEGF-A by FRC as measured by ELISA was not changed by exposure to PEMF, and blocking experiments demonstrated that the ELF-PEMF-induced osteoblast-derived endothelial mitogen observed in these studies was not VEGF-A, but some other soluble angiogenic mediator.

Endothelial Cell Recovery Between Comparator Polymer-Based Drug-Eluting Stents

The purpose of this study was to assess trends in endothelial coverage and recovery among leading polymer-based drug-eluting stents (DES). Autopsy studies of human U.S. Food and Drug Administration (FDA)-approved DES implanted coronary arteries suggest that complications of late stent thrombosis are associated with incomplete endothelial coverage of struts. Rabbits received sirolimus-eluting stents (SES), paclitaxel-eluting stents (PES), zotarolimus-eluting stents (ZES), and everolimus-eluting stents (EES) for 14 or 28 days along with MULTI-LINK (ML) Vision control stents. Endothelial coverage above and between struts was measured by morphometric analysis of images acquired through en face scanning electron microscopy. Dual fluorescent immunolabeling was performed for platelet-endothelial cell adhesion molecule (PECAM)-1 and thrombomodulin (TM), factors involved in cell-to-cell contact and thrombogenicity, respectively. In a separate analysis, the endothelial mitogen, vascular endothelial growth factor (VEGF), was also assessed. Varying rates of endothelialization among comparator DES were most notable at 14 days, where coverage above struts remained poor in SES, PES, and ZES (<or=30%) relative to EES and ML Vision controls (>or=70%), whereas no significant differences were observed at 28 days. Select DES with poor endothelialization showed a further reduced expression of PECAM-1. All DES showed an absence or weak expression of the antithrombotic cofactor TM. Incomplete endothelialization in select DES was further associated with increased VEGF secretion and messenger ribonucleic acid levels at 14 days, providing evidence of a transitional healing surface. The present study marks the first comparator analysis of endothelial coverage in leading polymeric DES, supporting disparities in arterial healing based on endothelial regrowth and recovery, favoring newer designs over the current generation of FDA-approved stents.

Overexpression of Netrin-1 Induces Neovascularization in the Adult Mouse Brain

Netrin-1 is a critical molecule for axonal pathfinding during embryo development, and because of its structural homology to the endothelial mitogens, it may share its effects on vascular network formation. Using an adeno-associated viral netrin-1 vector (AAV-NT-1) gene transfer, we demonstrated that netrin-1 was able to stimulate the proliferation and migration of human cerebral endothelial cells (HCECs) and human aortic smooth muscle cells (HASMCs) compared with the control (P<0.05), and could also promote HCEC tube formation on matrigel (P<0.05) in vitro. Moreover, netrin-1 hyperstimulation could promote focal neovascularization (P<0.05) in the adult brain in vivo. Unlike VEGF-induced microvessel increase, netrin-1-induced newly formed vessels showed an artery-like phenotype, with an intact endothelial cell monolayer surrounded by multiple cell layers, including smooth muscle cells and an astrocyte-connected outer layer. Our findings suggest that netrin-1 plays an important role in promoting blood vessel formation in the adult rodent central nervous system, and could have broad implication in cerebrovascular development and remodeling.

Inhibition of Intra-Abdominal Adhesion Formation With the Angiogenesis Inhibitor Sunitinib

To determine the effects of sunitinib, a vascular endothelial growth factor receptor 2 (VEGFR-2) antagonist, on intra-abdominal adhesions. In the United States, complications from adhesions cost $1 billion and account for 846,000 inpatient days annually. Endothelial mitogens, such as VEGF, are up-regulated during adhesion formation. Sunitinib, a tyrosine kinase inhibitor with antiangiogenic and antitumor properties, may prevent or reduce postoperative abdominal adhesions by VEGFR-2 inhibition. The cecum of 37 mice were abraded to promote adhesion formation and a silicone patch was sutured to the abdominal wall. The mice were randomized into two groups: Group 1 was treated with sunitinib in methylcellulose by oral gavage daily and Group 2 (control) received methylcellulose alone. After 10 d the mice were sacrificed and intra-abdominal adhesions were scored. The experiment was then repeated and mice were sacrificed on postoperative day 30 to assess the long-term effects of sunitinib. All 19 control mice developed intra-abdominal adhesions. Six of the 18 (33.3%) mice in the treatment group were adhesion-free. Collectively, the sunitinib-treated mice had a lower adhesion score [2.0 (IQR 0.0-5.0; range 0-8.0)] than the control group [5.0 (IQR 3.0-8.0; range 2.0-10.0) (P = 0.002)]. Long-term results were consistent with this finding [sunitinib 0.0 (IQR 0.0-3.0; range 0-7) and control 6.0 (IQR 3.0-7.0; range 0-12) (P = 0.049)]. Adhesion formation is angiogenesis-dependent and is in part mediated through VEGFR-2. Sunitinib, a VEGFR-2 antagonist, significantly reduces adhesion formation in a murine model. Antiangiogenic therapy may be an efficacious strategy to prevent or treat adhesions after intra-abdominal procedures.

Hypoxia-inducible Expression of a Natural cis-Antisense Transcript Inhibits Endothelial Nitric-oxide Synthase

The destabilization of endothelial nitric-oxide synthase (eNOS) mRNA in hypoxic endothelial cells may be important in the etiology of vascular diseases, such as pulmonary hypertension. Recently, an overlapping antisense transcript to eNOS/NOS3 was implicated in the post-transcriptional regulation of eNOS. We demonstrate here that expression of sONE, also known as eNOS antisense (NOS3AS) or autophagy 9-like 2 (APG9L2), is robustly induced by hypoxia or functional deficiency of von Hippel-Lindau protein. sONE is also up-regulated in the aortas of hypoxic rats. In hypoxic endothelial cells, sONE expression negatively correlates with eNOS expression. Blocking the hypoxic induction of sONE by RNA interference attenuates the fall in both eNOS RNA and protein. We provide evidence that the induction of sONE primarily involves transcript stabilization rather than increased transcriptional activity and is von Hippel-Lindaubut not hypoxia-inducible factor 2alpha-dependent. We also demonstrate that sONE transcripts are enriched in the nucleus of normoxic cells and that hypoxia promotes an increase in the level of cytoplasmic and polyribosome-associated, sONE mRNA. The finding that eNOS expression can be regulated by an overlapping cis-antisense transcript in a stimulus-dependent fashion provides evidence that sense/antisense interactions may play a previously unappreciated role in vascular disease pathogenesis.