Skeletal development and turnover occur in close spatial and temporal association with angiogenesis. Osteoblasts are ideally situated in bone to sense oxygen tension and respond to hypoxia by activating the hypoxia-inducible factor alpha (HIF alpha) pathway. Here we provide evidence that HIF alpha promotes angiogenesis and osteogenesis by elevating VEGF levels in osteoblasts. Mice overexpressing HIF alpha in osteoblasts through selective deletion of the von Hippel-Lindau gene (Vhl) expressed high levels of Vegf and developed extremely dense, heavily vascularized long bones. By contrast, mice lacking Hif1a in osteoblasts had the reverse skeletal phenotype of that of the Vhl mutants: long bones were significantly thinner and less vascularized than those of controls. Loss of Vhl in osteoblasts increased endothelial sprouting from the embryonic metatarsals in vitro but had little effect on osteoblast function in the absence of blood vessels. Mice lacking both Vhl and Hif1a had a bone phenotype intermediate between those of the single mutants, suggesting overlapping functions of HIFs in bone. These studies suggest that activation of the HIF alpha pathway in developing bone increases bone modeling events through cell-nonautonomous mechanisms to coordinate the timing, direction, and degree of new blood vessel formation in bone.

Respiratory distress syndrome (RDS) due to insufficient production of surfactant is a common and severe complication of preterm delivery. Here, we report that loss of the hypoxia-inducible transcription factor-2alpha (HIF-2alpha) caused fatal RDS in neonatal mice due to insufficient surfactant production by alveolar type 2 cells. VEGF, a target of HIF-2alpha, regulates fetal lung maturation: because VEGF levels in alveolar cells were reduced in HIF-2alpha-deficient fetuses; mice with a deficiency of the VEGF(164) and VEGF(188) isoforms or of the HIF-binding site in the VEGF promotor died of RDS; intrauterine delivery of anti-VEGF-receptor-2 antibodies caused RDS and VEGF stimulated production of surfactant proteins by cultured type 2 pneumocytes. Intrauterine delivery or postnatal intratracheal instillation of VEGF stimulated conversion of glycogen to surfactant and protected preterm mice against RDS. The pneumotrophic effect of VEGF may have therapeutic potential for lung maturation in preterm infants.

Vascular endothelial growth factor (VEGF)mRNA undergoes alternative splicing events that generate four different homodimeric isoforms, VEGFVEGFVEGFVEGFVEGFVEGFVEGFVEGFVEGF isoforms, transfected human embryonic kidney CEN4 cells expressing VEGFVEGFVEGFVEGFVEGFVEGFVEGF associated with the ECM was bioactive, because endothelial cells cultured on ECM derived from cells expressing VEGFVEGFVEGF can be released into a soluble and bioactive form by heparin or plasmin. ECM-bound VEGFVEGFVEGF and angiogenic potential.

Hypoxia stimulates angiogenesis through the binding of hypoxia-inducible factors to the hypoxia-response element in the vascular endothelial growth factor (Vegf) promotor. Here, we report that deletion of the hypoxia-response element in the Vegf promotor reduced hypoxic Vegf expression in the spinal cord and caused adult-onset progressive motor neuron degeneration, reminiscent of amyotrophic lateral sclerosis. The neurodegeneration seemed to be due to reduced neural vascular perfusion. In addition, VegfVegf receptor 2 and neuropilin 1. Acute ischemia is known to cause nonselective neuronal death. Our results indicate that chronic vascular insufficiency and, possibly, insufficient Vegf-dependent neuroprotection lead to the select degeneration of motor neurons.

OBJECTIVE

Erythropoietin (EPO) promotes proliferation and differentiation of erythroid progenitors and the survival of maturing erythroid cells. Here, we investigated the role of EPO in brain repair after stroke.

METHODS

Rats were treated with recombinant human EPO (rhEPO) at 24 hours after the onset of embolic stroke. An array of behavior tests was performed. Rats were euthanized 28 days after stroke for measurements of infarct volume, angiogenesis, and neurogenesis. In vitro, neurospheres derived from the subventricular zone (SVZ) of the rat and cerebral endothelial cells derived from the mouse were treated with rhEPO. Capillary-like tube formation and neuronal differentiation were measured.

RESULTS

Treatment with rhEPO significantly improved functional recovery, along with increases in density of cerebral microvessels at the stroke boundary and numbers of BrdU, doublecortin, and nestin immunoreactive cells in the SVZ. rhEPO treatment significantly increased brain levels of vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF). In vitro, rhEPO enhanced capillary tube formation of cerebral endothelial cells, which was inhibited by a specific VEGF receptor 2 antagonist (SU1498). Incubation of neurospheres derived from stroke SVZ with anti-EPO neutralizing antibody inhibited neurogenesis, whereas incubation of stroke-derived neurospheres with rhEPO enhanced neurogenesis.

CONCLUSIONS

Our data suggest that EPO-increased VEGF and BDNF may be involved in angiogenesis and neurogenesis, which could contribute to functional recovery.

The mechanisms through which hematopoietic cytokines accelerate revascularization are unknown. Here, we show that the magnitude of cytokine-mediated release of SDF-1 from platelets and the recruitment of nonendothelial CXCR4+ VEGFR1+ hematopoietic progenitors, 'hemangiocytes,' constitute the major determinant of revascularization. Soluble Kit-ligand (sKitL), thrombopoietin (TPO, encoded by Thpo) and, to a lesser extent, erythropoietin (EPO) and granulocyte-macrophage colony-stimulating factor (GM-CSF) induced the release of SDF-1 from platelets, enhancing neovascularization through mobilization of CXCR4+ VEGFR1+ hemangiocytes. Although revascularization of ischemic hindlimbs was partially diminished in mice deficient in both GM-CSF and G-CSF (Csf2-/- Csf3-/-), profound impairment in neovascularization was detected in sKitL-deficient Mmp9-/- as well as thrombocytopenic Thpo-/- and TPO receptor-deficient (Mpl-/-) mice. SDF-1-mediated mobilization and incorporation of hemangiocytes into ischemic limbs were impaired in Thpo-/-, Mpl-/- and Mmp9-/- mice. Transplantation of CXCR4+ VEGFR1+ hemangiocytes into Mmp9-/- mice restored revascularization, whereas inhibition of CXCR4 abrogated cytokine- and VEGF-A-mediated mobilization of CXCR4+ VEGFR1+ cells and suppressed angiogenesis. In conclusion, hematopoietic cytokines, through graded deployment of SDF-1 from platelets, support mobilization and recruitment of CXCR4+ VEGFR1+ hemangiocytes, whereas VEGFR1 is essential for their angiogenic competency for augmenting revascularization. Delivery of SDF-1 may be effective in restoring angiogenesis in individuals with vasculopathies.

Tumor cells stimulate the formation of stroma that secretes various mediators pivotal for tumor growth, including growth factors, cytokines, and proteases. However, little is known about the local regulation of these soluble mediators in the human tumor microenvironment. In this study, the local expression of cytokines, chemokines, and angiogenic factors was investigated in primary breast cancer tissue. The concentrations of interleukin (IL)-1, IL-4, IL-6, IL-10, IL-12, tumor necrosis factor (TNF)-alpha, IFN-gamma, IL-8, macrophage chemoattractant protein (MCP)-1, epithelial-neutrophil activating peptide-78, vascular endothelial growth factor, and thymidine phosphorylase (TP) were measured in 151 primary breast cancer extracts by ELISA. Tumor-associated macrophages (TAMs) were also examined by immunohistochemistry with anti-CD68 antibodies. The correlation between soluble mediators and the relationship between TAM count and soluble mediators were evaluated. MCP-1 concentration was correlated significantly with the level of vascular endothelial growth factor, TP, TNF-alpha, and IL-8, which are potent angiogenic factors. IL-4 concentration was correlated significantly with IL-8 and IL-10. On the other hand, an inverse association was observed between TP and IL-12. The level of MCP-1 was associated significantly with TAM accumulation. In the immunohistochemical analysis, MCP-1 expression was observed in both infiltrating macrophages and tumor cells. Prognostic analysis revealed that high expression of MCP-1, as well as of VEGF, was a significant indicator of early relapse. These findings indicate that interaction between the immune network system and angiogenesis is important for progression of human breast cancer, and that MCP-1 may play an important role in the regulation of angiogenesis and the immune system.

Antiangiogenic drugs targeting the VEGF pathway have slowed metastatic disease progression in some patients, leading to progression-free survival (PFS) and overall survival benefits compared with controls. However, the results are more modest than predicted by most preclinical testing and benefits in PFS are frequently not accompanied by overall survival improvements. Questions have emerged about the basis of drug resistance and the limitations of predictive preclinical models, and also about whether the nature of disease progression following antiangiogenic therapy is different to classic cytotoxic therapies-in particular whether therapy may lead to more invasive or metastatic behavior. In addition, because of recent clinical trial failures of antiangiogenic therapy in patients with early-stage disease, and the fact that there are hundreds of trials underway in perioperative neoadjuvant and adjuvant settings, there is now greater awareness about the lack of appropriate preclinical testing that preceded these studies. Improved preclinical assessment of all stages of metastatic disease should be a priority for future antiangiogenic drug discovery and development.

Vascular endothelial growth factors and their endothelial tyrosine kinase receptors are central regulators of vasculogenesis, angiogenesis and lymphangiogenesis. VEGF signalling through VEGFR-2 is the major angiogenic pathway, and blockage of VEGF/VEGFR-2 signalling is the first anti-angiogenic strategy for cancer therapy. VEGFR-1 seems to act as a negative regulator of VEGF-mediated angiogenesis during development, and as a stimulator of pathological angiogenesis when activated by its specific ligands PlGF and VEGF-B. PlGF recruits angiogenic macrophages to tumours, and targeting PlGF could therefore be beneficial in cancer. For VEGF-B, with very limited angiogenic potential, a new role has been identified in regulating lipid metabolism in the heart. VEGF-C and VEGF-D induce lymphangiogenesis via VEGFR-3 and have also been shown to be lymphangiogenic in tumours, stimulating metastasis. Mouse models of lymphoedema have established VEGF-C as a promising agent for pro-lymphangiogenic therapy. In addition to lymphangiogenesis, VEGFR-3 has also been shown to be important for angiogenesis, acting together with VEGF/VEGFR-2 and Dll4/Notch signalling to control angiogenic sprouting. Increasing knowledge of the mechanisms regulating (lymph)angiogenesis should enable the development of better agents to combat metastasis and the resistance of tumours towards anti-angiogenic treatment, and of pro-(lymph)angiogenic treatment methods for ischaemic diseases and lymphoedema.

Vascular endothelial growth factor (VEGF) is a fundamental regulator of normal and abnormal angiogenesis. Recent evidence indicates that VEGF is essential for embryonic vasculogenesis and angiogenesis. Furthermore, VEGF is required for the cyclical blood vessel proliferation in the female reproductive tract and for longitudinal bone growth and endochondral bone formation. Substantial experimental evidence also implicates VEGF in pathological angiogenesis. Anti-VEGF monoclonal antibodies or other VEGF inhibitors block the growth of many tumor cell lines in nude mice. Furthermore, the concentrations of VEGF are elevated in the aqueous and vitreous humors of patients with proliferative retinopathies such as the diabetic retinopathy. In addition, VEGF-induced angiogenesis results in a therapeutic benefit in several animal models of myocardial or limb ischemia. Currently, both therapeutic angiogenesis using recombinant VEGF or VEGF gene transfer and inhibition of VEGF-mediated pathological angiogenesis are being pursued.

Vascular endothelial growth factors (VEGFs) regulate vascular development, angiogenesis and lymphangiogenesis by binding to a number of receptors. VEGFR-1 is required for the recruitment of haematopoietic stem cells and the migration of monocytes and macrophages, VEGFR-2 regulates vascular endothelial function and VEGFR-3 regulates lymphatic endothelial cell function. Over the last decade, considerable progress has been made in delineating the VEGFR-2 specific intracellular signalling cascades leading to proliferation, migration, survival and increased permeability, each of which contributes to the angiogenic response. Furthermore, therapeutic inhibition of VEGFR-2 action is now having an impact in the clinic for the treatment of a number of diseases.

Nitric oxide (NO) plays a critical role in vascular endothelial growth factor (VEGF)-induced angiogenesis and vascular hyperpermeability. However, the relative contribution of different NO synthase (NOS) isoforms to these processes is not known. Here, we evaluated the relative contributions of endothelial and inducible NOS (eNOS and iNOS, respectively) to angiogenesis and permeability of VEGF-induced angiogenic vessels. The contribution of eNOS was assessed by using an eNOS-deficient mouse, and iNOS contribution was assessed by using a selective inhibitor [l-N(6)-(1-iminoethyl) lysine, l-NIL] and an iNOS-deficient mouse. Angiogenesis was induced by VEGF in type I collagen gels placed in the mouse cranial window. Angiogenesis, vessel diameter, blood flow rate, and vascular permeability were proportional to NO levels measured with microelectrodes: Wild-type (WT)>> or = WT with l-NIL or iNOS(-/-)>> eNOS(-/-)>> or = eNOS(-/-) with l-NIL. The role of NOS in VEGF-induced acute vascular permeability increase in quiescent vessels also was determined by using eNOS- and iNOS-deficient mice. VEGF superfusion significantly increased permeability in both WT and iNOS(-/-) mice but not in eNOS(-/-) mice. These findings suggest that eNOS plays a predominant role in VEGF-induced angiogenesis and vascular permeability. Thus, selective modulation of eNOS activity is a promising strategy for altering angiogenesis and vascular permeability in vivo.

Obstructive sleep apnoea syndrome (OSA) is associated with increased cardiovascular morbidity and mortality. However, the underlying mechanisms are not entirely understood. This review will summarize the evidence that substantiates the notion that the repeated apnoea-related hypoxic events in OSA, similarly to hypoxia/reperfusion injury, initiate oxidative stress. Thus, affecting energy metabolism, redox-sensitive gene expression, and expression of adhesion molecules. A limited number of studies substantiate this hypothesis directly by demonstrating increased free radical production in OSA leukocytes and increased plasma-lipid peroxidation. A great number of studies, however, support this hypothesis indirectly. Increase in circulating levels of adenosine and urinary uric acid in OSA are implicated with increased production of reactive oxygen species (ROS). Activation of redox-sensitive gene expression is suggested by the increase in some protein products of these genes, including VEGF, erythropoietin, endothelin-1, inflammatory cytokines and adhesion molecules. These implicate the participation of redox-sensitive transcription factors as HIF-1 AP-1 and NFkappaB. Finally, adhesion molecule-dependent increased avidity of OSA monocytes to endothelial cells, combined with diminished NO bioavailability, lead to exaggerated endothelial cell damage and dysfunction. Cumulatively, these processes may exacerbate atherogenic sequelae in OSA.

This study demonstrates that a CD34(-), vascular endothelial cadherin(-) (VE-cadherin(-)), AC133(+), and fetal liver kinase(+) (Flk1(+)) multipotent adult progenitor cell (MAPC) that copurifies with mesenchymal stem cells from postnatal human bone marrow (BM) is a progenitor for angioblasts. In vitro, MAPCs cultured with VEGF differentiate into CD34(+), VE-cadherin(+), Flk1(+) cells - a phenotype that would be expected for angioblasts. They subsequently differentiate into cells that express endothelial markers, function in vitro as mature endothelial cells, and contribute to neoangiogenesis in vivo during tumor angiogenesis and wound healing. This in vitro model of preangioblast-to-endothelium differentiation should prove very useful in studying commitment to the angioblast and beyond. In vivo, MAPCs can differentiate in response to local cues into endothelial cells that contribute to neoangiogenesis in tumors. Because MAPCs can be expanded in culture without obvious senescence for more than 80 population doublings, they may be an important source of endothelial cells for cellular pro- or anti-angiogenic therapies.

Platelets, in addition to their function in hemostasis, play an important role in wound healing and tumor growth. Because platelets contain angiogenesis stimulators and inhibitors, the mechanisms by which platelets regulate angiogenesis remain unclear. As platelets adhere to activated endothelium, their action can enhance or inhibit local angiogenesis. We therefore suspected a higher organization of angiogenesis regulators in platelets. Using double immunofluorescence and immunoelectron microscopy, we show that pro- and antiangiogenic proteins are separated in distinct subpopulations of alpha-granules in platelets and megakaryocytes. Double immunofluorescence labeling of vascular endothelial growth factor (VEGF) (an angiogenesis stimulator) and endostatin (an angiogenesis inhibitor), or for thrombospondin-1 and basic fibroblast growth factor, confirms the segregation of stimulators and inhibitors into separate and distinct alpha-granules. These observations motivated the hypothesis that distinct populations of alpha-granules could undergo selective release. The treatment of human platelets with a selective PAR4 agonist (AYPGKF-NH(2)) resulted in release of endostatin-containing granules, but not VEGF-containing granules, whereas the selective PAR1 agonist (TFLLR-NH(2)) liberated VEGF, but not endostatin-containing granules. In conclusion, the separate packaging of angiogenesis regulators into pharmacologically and morphologically distinct populations of alpha-granules in megakaryocytes and platelets may provide a mechanism by which platelets can locally stimulate or inhibit angiogenesis.

Formation of lymphatic metastasis is the initial step of generalized spreading of tumor cells and predicts poor clinical prognosis. Lymphatic vessels generally arise within the peritumoral stroma, although the lymphangiopoietic vascular endothelial growth factors (VEGF)-C and -D are produced by tumor cells. In a carefully selected collection of human cervical cancers (stage pT1b1) we demonstrate by quantitative immunohistochemistry and in situ hybridization that density of lymphatic microvessels is significantly increased in peritumoral stroma, and that a subset of stromal cells express large amounts of VEGF-C and VEGF-D. The density of cells producing these vascular growth factors correlates with peritumoral inflammatory stroma reaction, lymphatic microvessel density, and indirectly with peritumoral carcinomatous lymphangiosis and frequency of lymph node metastasis. The VEGF-C- and VEGF-D-producing stroma cells were identified in situ as a subset of activated tumor-associated macrophages (TAMs) by expression of a panel of macrophage-specific markers, including CD68, CD23, and CD14. These TAMs also expressed the VEGF-C- and VEGF-D-specific tyrosine kinase receptor VEGFR-3. As TAMs are derived from monocytes in the circulation, a search in peripheral blood for candidate precursors of VEGFR-3-expressing TAMs revealed a subfraction of CD14-positive, VEGFR-3-expressing monocytes, that, however, failed to express VEGF-C and VEGF-D. Only after in vitro incubation with tumor necrosis factor-alpha, lipopolysaccharide, or VEGF-D did these monocytes start to synthesize VEGF-C de novo. In conclusion VEGF-C-expressing TAMs play a novel role in peritumoral lymphangiogenesis and subsequent dissemination in human cancer.

Increased glucose uptake and accumulation of lactate, even under normoxic conditions (i.e., aerobic glycolysis or the Warburg Effect), is a common feature of cancer cells. This phenomenon clearly indicates that lactate is not a surrogate of tumor hypoxia. Tumor lactate can predict for metastases and overall survival of patients, as shown by several studies of different entities. Metastasis of tumors is promoted by lactate-induced secretion of hyaluronan by tumor-associated fibroblasts that create a milieu favorable for migration. Lactate itself has been found to induce the migration of cells and cell clusters. Furthermore, radioresistance has been positively correlated with lactate concentrations, suggesting an antioxidative capacity of lactate. Findings on interactions of tumor metabolites with immune cells indicate a contribution of lactate to the immune escape. Furthermore, lactate bridges the gap between high lactate levels in wound healing, chronic inflammation, and cancer development. Tumor cells ensure sufficient oxygen and nutrient supply for proliferation through lactate-induced secretion of VEGF, resulting in the formation of new vessels. In summary, accumulation of lactate in solid tumors is a pivotal and early event in the development of malignancies. The determination of lactate should enter further clinical trials to confirm its relevance in cancer biology.

SUMOylation is a dynamic process, catalyzed by SUMO-specific ligases and reversed by Sentrin/SUMO-specific proteases (SENPs). The physiologic consequences of SUMOylation and deSUMOylation are not fully understood. Here we investigate the phenotypes of mice lacking SENP1 and find that SENP1(-/-) embryos show severe fetal anemia stemming from deficient erythropoietin (Epo) production and die midgestation. We determine that SENP1 controls Epo production by regulating the stability of hypoxia-inducible factor 1alpha (HIF1alpha) during hypoxia. Hypoxia induces SUMOylation of HIF1alpha, which promotes its binding to a ubiquitin ligase, von Hippel-Lindau (VHL) protein, through a proline hydroxylation-independent mechanism, leading to its ubiquitination and degradation. In SENP1(-/-) MEFs, hypoxia-induced transcription of HIF1alpha-dependent genes such as vascular endothelial growth factor (VEGF) and glucose transporter 1 (Glut-1) is markedly reduced. These results show that SENP1 plays a key role in the regulation of the hypoxic response through regulation of HIF1alpha stability and that SUMOylation can serve as a direct signal for ubiquitin-dependent degradation.

Vascular endothelial growth factor-A (VEGF-A) has recently been recognized as an important neuroprotectant in the central nervous system. Given its position as an anti-angiogenic target in the treatment of human diseases, understanding the extent of VEGF's role in neural cell survival is paramount. Here, we used a model of ischemia-reperfusion injury and found that VEGF-A exposure resulted in a dose-dependent reduction in retinal neuron apoptosis. Although mechanistic studies suggested that VEGF-A-induced volumetric blood flow to the retina may be partially responsible for the neuroprotection, ex vivo retinal culture demonstrated a direct neuroprotective effect for VEGF-A. VEGF receptor-2 (VEGFR2) expression was detected in several neuronal cell layers of the retina, and functional analyses showed that VEGFR2 was involved in retinal neuroprotection. VEGF-A was also shown to be involved in the adaptive response to retinal ischemia. Ischemic preconditioning 24 hours before ischemia-reperfusion injury increased VEGF-A levels and substantially decreased the number of apoptotic retinal cells. The protective effect of ischemic preconditioning was reversed after VEGF-A inhibition. Finally, chronic inhibition of VEGF-A function in normal adult animals led to a significant loss of retinal ganglion cells yet had no observable effect on several vascular parameters. These findings have implications for both neural pathologies and ocular vascular diseases, such as diabetic retinopathy and age-related macular degeneration.

Edema occurs in asthma and other inflammatory diseases when the rate of plasma leakage from blood vessels exceeds the drainage through lymphatic vessels and other routes. It is unclear to what extent lymphatic vessels grow to compensate for increased leakage during inflammation and what drives the lymphangiogenesis that does occur. We addressed these issues in mouse models of (a) chronic respiratory tract infection with Mycoplasma pulmonis and (b) adenoviral transduction of airway epithelium with VEGF family growth factors. Blood vessel remodeling and lymphangiogenesis were both robust in infected airways. Inhibition of VEGFR-3 signaling completely prevented the growth of lymphatic vessels but not blood vessels. Lack of lymphatic growth exaggerated mucosal edema and reduced the hypertrophy of draining lymph nodes. Airway dendritic cells, macrophages, neutrophils, and epithelial cells expressed the VEGFR-3 ligands VEGF-C or VEGF-D. Adenoviral delivery of either VEGF-C or VEGF-D evoked lymphangiogenesis without angiogenesis, whereas adenoviral VEGF had the opposite effect. After antibiotic treatment of the infection, inflammation and remodeling of blood vessels quickly subsided, but lymphatic vessels persisted. Together, these findings suggest that when lymphangiogenesis is impaired, airway inflammation may lead to bronchial lymphedema and exaggerated airflow obstruction. Correction of defective lymphangiogenesis may benefit the treatment of asthma and other inflammatory airway diseases.

BACKGROUND

Multiple gene expression based prognostic biomarkers have been repeatedly identified in gastric carcinoma. However, without confirmation in an independent validation study, their clinical utility is limited. Our goal was to establish a robust database enabling the swift validation of previous and future gastric cancer survival biomarker candidates.

RESULTS

The entire database incorporates 1,065 gastric carcinoma samples, gene expression data. Out of 29 established markers, higher expression of BECN1 (HR = 0.68, p = 1.5E-05), CASP3 (HR = 0.5, p = 6E-14), COX2 (HR = 0.72, p = 0.0013), CTGF (HR = 0.72, p = 0.00051), CTNNB1 (HR = 0.47, p = 4.3E-15), MET (HR = 0.63, p = 1.3E-05), and SIRT1 (HR = 0.64, p = 2.2E-07) correlated to longer OS. Higher expression of BIRC5 (HR = 1.45, p = 1E-04), CNTN1 (HR = 1.44, p = 3.5E- 05), EGFR (HR = 1.86, p = 8.5E-11), ERCC1 (HR = 1.36, p = 0.0012), HER2 (HR = 1.41, p = 0.00011), MMP2 (HR = 1.78, p = 2.6E-09), PFKB4 (HR = 1.56, p = 3.2E-07), SPHK1 (HR = 1.61, p = 3.1E-06), SP1 (HR = 1.45, p = 1.6E-05), TIMP1 (HR = 1.92, p = 2.2E- 10) and VEGF (HR = 1.53, p = 5.7E-06) were predictive for poor OS.

METHODS

We integrated samples of three major cancer research centers (Berlin, Bethesda and Melbourne datasets) and publicly available datasets with available follow-up data to form a single integrated database. Subsequently, we performed a literature search for prognostic markers in gastric carcinomas (PubMed, 2012-2015) and re-validated their findings predicting first progression (FP) and overall survival (OS) using uni- and multivariate Cox proportional hazards regression analysis.

CONCLUSIONS

The major advantage of our analysis is that we evaluated all genes in the same set of patients thereby making direct comparison of the markers feasible. The best performing genes include BIRC5, CASP3, CTNNB1, TIMP-1, MMP-2, SIRT, and VEGF.

Src kinase activity was found to protect endothelial cells from apoptosis during vascular endothelial growth factor (VEGF)-, but not basic fibroblast growth factor (bFGF)-, mediated angiogenesis in chick embryos and mice. In fact, retroviral targeting of kinase-deleted Src to tumor-associated blood vessels suppressed angiogenesis and the growth of a VEGF-producing tumor. Although mice lacking individual Src family kinases (SFKs) showed normal angiogenesis, mice deficient in pp60c-src or pp62c-yes showed no VEGF-induced vascular permeability (VP), yet fyn-/- mice displayed normal VP. In contrast, inflammation-mediated VP appeared normal in Src-deficient mice. Therefore, VEGF-, but not bFGF-, mediated angiogenesis requires SFK activity in general, whereas the VP activity of VEGF specifically depends on the SFKs, Src, or Yes.

Molecular imaging is a key component of 21st-century cancer management. The vascular endothelial growth factor (VEGF)/VEGF receptor signaling pathway and integrin alpha v beta 3, a cell adhesion molecule, play pivotal roles in regulating tumor angiogenesis, the growth of new blood vessels. This review summarizes the current status of tumor angiogenesis imaging with SPECT, PET, molecular MRI, targeted ultrasound, and optical techniques. For integrin alpha v beta 3 imaging, only nanoparticle-based probes, which truly target the tumor vasculature rather than tumor cells because of poor extravasation, are discussed. Once improvements in the in vivo stability, tumor-targeting efficacy, and pharmacokinetics of tumor angiogenesis imaging probes are made, translation to clinical applications will be critical for the maximum benefit of these novel agents. The future of tumor angiogenesis imaging lies in multimodality and nanoparticle-based approaches, imaging of protein-protein interactions, and quantitative molecular imaging. Combinations of multiple modalities can yield complementary information and offer synergistic advantages over any modality alone. Nanoparticles, possessing multifunctionality and enormous flexibility, can allow for the integration of therapeutic components, targeting ligands, and multimodality imaging labels into one entity, termed "nanomedicine," for which the ideal target is tumor neovasculature. Quantitative imaging of tumor angiogenesis and protein-protein interactions that modulate angiogenesis will lead to more robust and effective monitoring of personalized molecular cancer therapy. Multidisciplinary approaches and cooperative efforts from many individuals, institutions, industries, and organizations are needed to quickly translate multimodality tumor angiogenesis imaging into multiple facets of cancer management. Not limited to cancer, these novel agents can also have broad applications for many other angiogenesis-related diseases.

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen in vitro and an angiogenic inducer in vivo. The tyrosine kinases Flt-1 (VEGFR-1) and Flk-1/KDR (VEGFR-2) are high affinity VEGF receptors. VEGF plays an essential role in developmental angiogenesis and is important also for reproductive and bone angiogenesis. Substantial evidence also implicates VEGF as a mediator of pathological angiogenesis. Anti-VEGF monoclonal antibodies and other VEGF inhibitors block the growth of several tumor cell lines in nude mice. Clinical trials with VEGF inhibitors in a variety of malignancies are ongoing. Recently, a humanized anti-VEGF monoclonal antibody (bevacizumab; Avastin) has been approved by the FDA as a first-line treatment for metastatic colorectal cancer in combination with chemotherapy. Furthermore, VEGF is implicated in intraocular neovascularization associated with diabetic retinopathy and age-related macular degeneration.