Impaired balance between mature and immature myeloid cells is one of the hallmarks of cancer. In cancer patients as well as in mouse models there is increasing evidence that progressive tumor growth ...is associated with an accumulation of immature myeloid cells, monocytes/macrophages, and with a decreased number and function of dendritic cells (DC). This review examines recent findings on the contribution of immature myeloid cells (ImC) to cancer-induced immune suppression.
Vascular endothelial growth factor (VEGF) is a potent mitogen for endothelial cells and plays an important role in physiological and tumor angiogenesis. The human VEGF gene has eight exons. Different ...VEGF isoforms are expressed via alternative RNA splicing and VEGF121 and VEGF165 are the major isoforms present in human tissues. The exact roles of these different VEGF isoforms are not totally clear. Assays to detect specific VEGF isoforms in biological samples are needed to understand the biological functions of these different VEGF isoforms and to better assess their potential use as predicative biomarkers for anti-angiogenic therapy. Because monoclonal antibodies specific to different VEGF isoforms are lacking, we used antibodies directed to different epitopes on VEGF165 in a set of three enzyme-linked immunosorbent assays (ELISAs) to assess the amount of VEGF121 and VEGF165 as well as VEGF110, which can be generated by plasmin cleavage in vivo. The first ELISA detects VEGF165. The second ELISA detects both VEGF121 and VEGF165. The third ELISA detects VEGF165, VEGF121, and VEGF110. The concentrations of VEGF121 can be assessed from the difference in VEGF concentrations measured by the second and the first ELISAs; the concentrations of VEGF110 can be assessed from the difference in VEGF concentrations measured by the third and the second ELISAs. The same assay strategy may be used to assess the amount of other VEGF isoforms if antibodies directed against the desired amino acids in those isoforms can be obtained.
Introduction
Neovascular age-related macular degeneration (nAMD) represents a leading cause of irreversible visual loss affecting the quality of life of millions of elderly patients worldwide. ...Although the introduction of intravitreal injections with anti-vascular endothelial growth factors (anti-VEGF) agents has revolutionized the management of nAMD, their effectiveness and ultimate success are limited by several therapeutic challenges. Consequently, real-world efficacy appears significantly inferior to that reported by randomized controlled trials. Therefore, further innovative, long-term treatment options are essential to improve the prognosis and outcome of nAMD therapy.
Methods
Emerging pharmacological therapies for nAMD and those currently in clinical trials are reviewed and their mechanism of action, safety, and efficacy are discussed. The evidence presented herein has been collected from online databases PubMed, Cochrane library, and the ClinicalTrials.gov site.
Results
A number of promising technologies and novel anti-VEGF therapies are currently being tested and some have already reached phase III trials. Anti-VEGF agents with enhanced durability and possibly efficacy, gene therapy, angiogenic targets, alternative drug delivery routes such as sustained delivery implants, drug carriers, and encapsulated cell technology are currently being explored. We briefly discuss the potential value of these options.
Conclusion
Several options may optimize future nAMD management. On the basis of current, albeit limited evidence, the most promising technology to reach clinical practice soon appears to be the sustained drug delivery options, which may improve visual outcome and reduce the socioeconomic burden of nAMD.
FLT3 (fms-related tyrosine kinase/Flk2/Stk-2) is a receptor tyrosine kinase (RTK) primarily expressed on hematopoietic cells. In blasts from acute myelogenous leukemia (AML) patients, 2 classes of ...FLT3 activating mutations have been identified: internal tandem duplication (ITD) mutations in the juxtamembrane domain (25%-30% of patients) and point mutations in the kinase domain activation loop (7%-8% of patients). FLT3-ITD mutations are the most common molecular defect identified in AML and have been shown to be an independent prognostic factor for decreased survival. FLT3-ITD is therefore an attractive molecular target for therapy. SU11248 is a recently described selective inhibitor with selectivity for split kinase domain RTKs, including platelet-derived growth factor receptors, vascular endothelial growth factor receptors, and KIT. We show that SU11248 also has potent activity against wild-type FLT3 (FLT3-WT), FLT3-ITD, and FLT3 activation loop (FLT3-Asp835) mutants in phosphorylation assays. SU11248 inhibits FLT3-driven phosphorylation and induces apoptosis in vitro. In addition, SU11248 inhibits FLT3-induced VEGF production. The in vivo efficacy of SU11248 was investigated in 2 FLT3-ITD models: a subcutaneous tumor xenograft model and a bone marrow engraftment model. We show that SU11248 (20 mg/kg/d) dramatically regresses FLT3-ITD tumors in the subcutaneous tumor xenograft model and prolongs survival in the bone marrow engraftment model. Pharmacokinetic and pharmacodynamic analysis in subcutaneous tumors showed that a single administration of an efficacious drug dose potently inhibits FLT3-ITD phosphorylation for up to 16 hours following a single dose. These results suggest that further exploration of SU11248 activity in AML patients is warranted.
BACKGROUND/AIMS Vascular endothelial growth factor (VEGF) plays a key role in regulation of tumour associated angiogenesis. In the current study we analysed expression of VEGF and its receptors in ...human hepatocellular carcinoma (HCC) and investigated the molecular mechanisms of VEGF regulation by hypoxia. METHODS VEGF, kinase domain region (KDR)/fetal liver kinase 1 (flk-1), and flt-1 expression were examined by immunohistochemistry and in situ hybridisation in 15 human HCC tissues. Expression of VEGF and regulation by hypoxia were assessed in three human HCC cell lines using a quantitative competitive reverse transcription-polymerase chain reaction, ELISA, and a series of 5′ deletion reporter gene constructs of the human VEGF promoter in transient transfection assays. RESULTS We observed over expression of VEGF mRNA and protein in HCC compared with cirrhosis or normal liver. Expression of VEGF in tumour cells was strongly increased in areas directly adjacent to necrotic/hypoxic regions. Both VEGF receptors were detected in vascular endothelia of HCC while only KDR/flk-1 receptors were detected in endothelial cells of cirrhotic livers. Expression of VEGF was observed in all human HCC cell lines examined. Hypoxia (1% oxygen) resulted in profound upregulation of VEGF mRNA and protein levels. Furthermore, hypoxia treatment resulted in a doubling of VEGF mRNA stability. Deletion analysis of the human VEGF 5′ flanking region −2018 and +50 demonstrated induction of VEGF promoter activity under hypoxic conditions which was significantly decreased following deletion of the region −1286 and −789 suggesting a substantial contribution of the −975 putative hypoxia inducible factor 1 binding site to hypoxia mediated transcriptional activation of the VEGF gene. CONCLUSION These data suggest hypoxia as a central stimulus of angiogenesis in human HCC through upregulation of VEGF gene expression by at least two distinct molecular mechanisms: activation of VEGF gene transcription and an increase in VEGF mRNA stability.
Lymphatic system plays an important role in maintaining the fluid homeostasis and normal immune responses, anatomic or functional obstruction of which leads to lymphedema, and treatments for ...therapeutic lymphangiogenesis are efficiency for secondary lymphedema. Total saponins of panaxnotoginseng (PNS) are a mixture isolated from Panaxnotoginseng (Burkill) F.H.Chen, which has been used as traditional Chinese medicine in China for treatment of cardio- and cerebro-vascular diseases. The aim of this study was to determine the effect and mechanism of PNS on lymphangiogenesis.
The Tg (fli1: egfp; gata1: dsred) transgenic zebrafish embryos were treated with different concentrations of PNS (10, 50, 100μM) for 48h with or without the 6h pretreatment of the 30μM Vascular endothelial growth factors receptor (VEGFR)-3 kinase inhibitor, followed with morphological observation and lympangiogenesis of thoracic duct assessment. The effect of PNS on cell viability, migration, tube formation and Vascular endothelial growth factors (VEGF)-C mRNA and protein expression of lymphatic endothelial cells (LECs) were determined. The role of phosphatidylinositol-3 (PI-3)-kinase (PI3K), extracellular signal-regulated kinase (ERK)1/2 pathways, c-Jun N-terminal kinase (JNK) and P38 mitogen activated protein kinases (MAPK) signaling in PNS-induced VEGF-C expression of LECs by using pharmacological agents to block each signal.
PNS promotes lymphangiogenesis of thoracic duct in zebrafish with or without VEGFR3 Kinase inhibitor pre-impairment. PNS promotes proliferation, migration and tube formation of LECs. The tube formation induced by PNS could be blocked by VEGFR3 Kinase inhibitor. PNS induce VEGF-C expression of LEC, which could be blocked by ERK1/2, PI3K and P38MAPK signaling inhibitors.
PNS activates lymphangiogenesis both in vivo and in vitro by up-regulating VEGF-C expression and activation of ERK1/2, PI3K and P38MAPK signaling. These findings provide a novel insight into the role of PNS in lymphangiogenesis and suggest that it might be an attractive and suitable therapeutic agent for treating secondary lymphedema or other lymphatic system impairment related disease.
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Cancer treatment has been revolutionized by the advent of new molecular targeted and immunotherapeutic agents. Identification of the role of tumor angiogenesis changed the understanding of many ...tumors. After the unsuccessful results with chemotherapy, sorafenib, by interfering with angiogenic pathways, has become pivotal in the treatment of hepatocellular carcinoma. Sorafenib is the only systemic treatment to show a modest but statistically significant survival benefit. All novel drugs and strategies for treatment of advanced hepatocellular carcinoma must be compared with the results obtained with sorafenib, but no new drug or drug combination has yet achieved better results. In our opinion, the efforts to impact the natural history of the disease will be directed not only to drug development but also to understanding the underlying liver disease(usually hepatitis B virus- or hepatitis C virus-related) and to interrupting the progression of cirrhosis. It will be important to define the role and amount of mutations in the complex pathogenesis of hepatocellular carcinoma and to better integrate locoregional and systemic therapies. It will be important also to optimize the therapeutic strategies with existing chemotherapeutic drugs and new targeted agents.
In addition to its roles in the maintenance of interstitial fluid homeostasis and immunosurveillance, the lymphatic system has a critical role in regulating transport of dietary lipids to the blood ...circulation. Recent work within the past two decades has identified an important relationship between lymphatic dysfunction and patients with metabolic disorders, such as obesity and type 2 diabetes, in part characterized by abnormal lipid metabolism and transport. Utilization of several genetic mouse models, as well as non-genetic models of diet-induced obesity and metabolic syndrome, has demonstrated that abnormal lymphangiogenesis and poor collecting vessel function, characterized by impaired contractile ability and perturbed barrier integrity, underlie lymphatic dysfunction relating to obesity, diabetes, and metabolic syndrome. Despite the progress made by these models, the contribution of the lymphatic system to metabolic disorders remains understudied and new insights into molecular signaling mechanisms involved are continuously developing. Here, we review the current knowledge related to molecular mechanisms resulting in impaired lymphatic function within the context of obesity and diabetes. We discuss the role of inflammation, transcription factor signaling, vascular endothelial growth factor-mediated signaling, and nitric oxide signaling contributing to impaired lymphangiogenesis and perturbed lymphatic endothelial cell barrier integrity, valve function, and contractile ability in collecting vessels as well as their viability as therapeutic targets to correct lymphatic dysfunction and improve metabolic syndromes.
Angiogenic magnetic hydrogels are attractive for tissue engineering applications because their integrated properties can improve angiogenesis while providing magnetic guidance and stimulation for ...tissue healing. In this study, we synthesized magnetic nanoparticles (MNPs) with curcumin as an angiogenic agent, referred to as CMNPs, via a one-pot coprecipitation method. We dispersed CMNPs in hyaluronic acid (HyA) to create angiogenic magnetic hydrogels. CMNPs showed a slightly reduced average diameter compared to that of MNPs and a curcumin content of 11.91%. CMNPs exhibited a sustained slow release of curcumin when immersed in a revised simulated body fluid (rSBF). Both CMNPs and MNPs showed a dose-dependent cytocompatibility when cultured with bone marrow-derived mesenchymal stem cells (BMSCs) using the direct exposure culture method in vitro. The average BMSC density increased when the concentrations of CMNPs or MNPs increased from 100 to 500 μg/mL, but the cell density decreased when the nanoparticle concentration reached 1000 μg/mL. CMNPs showed a weaker magnetic response than MNPs both in air and in water immediately after synthesis but retained the magnetism better than MNPs when embedded in the HyA hydrogel because of less oxidation. CMNPs were able to respond to magnetic guidance even when the porcine skin or muscle tissues were placed in between the nanoparticles and external magnet. The magnetic hydrogels of HyA_CMNP and HyA_MNP promoted the adhesion of BMSCs in a direct exposure culture. The HyA_CMNP group also showed the highest secretion of the vascular endothelial growth factor with the release of curcumin in vitro. Overall, our magnetic hydrogels integrated the desirable properties of cytocompatibility and angiogenesis with magnetic guidance, thus proving to be promising for improving tissue regeneration.
The role of the vascular endothelial growth factors (VEGF) receptors (KDR and Flt-1) and their characteristics in VEGF-induced vasodilation in human vessels is unclear. This study investigated the in ...vitro vasorelaxant effects of KDR-selective (KDR-SM) and Flt-1-selective mutants (Flt-1-SM) in the human internal mammary artery (IMA). IMA segments (n = 183) taken from 48 patients were studied in organ baths. The cumulative concentration (−12 to −8 log10M)-relaxation curves were established for VEGF, KDR-SM, Flt-1-SM, and placenta growth factor (PlGF) in the absence or presence of indomethacin (INDO, 7 μM), N-nitro-L-arginine (L-NNA, 300 μM), L-NNA + oxyhemoglobin (HbO, 20 μM), or INDO + L-NNA + HbO. The VEGF-induced relaxation was abolished in endothelium-denuded IMA. In the endothelium-intact vessel rings, VEGF (63.2 ± 3.9%) induced significantly more (P < 0.001) relaxation than Flt-1-SM (28.5 ± 4.3%, 95% CI 18.1-51.3%), and PlGF (26.0 ± 4.7%, 95% CI 17.6-56.8%). The maximal relaxation induced by KDR-SM (53.0 ± 4.0%) was only slightly less than that by VEGF (P = 0.075) but significantly more than that by Flt-1-SM (P = 0.001, 95% CI 7.8-41.1%). Pretreatment of INDO or L-NNA + HbO significantly (P < 0.001) inhibited the relaxation by VEGF (21.2 ± 3.9% or 23.3 ± 4.3%) and KDR-SM (9.8 ± 8.2% or 10.1 ± 17.8%). INDO + L-NNA + HbO completely inhibited the relaxation by VEGF, KDR-SM, or Flt-1-SM. KDR may be the dominant receptor in mediating the VEGF-mediated relaxation, which is regulated by both PGI2 and nitric oxide but probably not by endothelium-derived hyperpolarizing factor, in the human IMA. This study gives insight into the characteristics of the VEGF-mediated vasodilation and provides a scientific basis for potential clinical application of VEGF/KDR-SM in ischemic heart disease.
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