The impact of the receptor binding profiles of the vascular endothelial growth factors on their angiogenic features.

Vascular endothelial growth factors (VEGFs) are potential therapeutic agents for treatment of ischemic diseases. Their angiogenic effects are mainly mediated through VEGF receptor 2 (VEGFR2). Receptor binding, signaling, and biological efficacy of several VEGFR2 ligands were compared to determine their characteristics regarding angiogenic activity and vascular permeability. Tested VEGFR2 ligands induced receptor tyrosine phosphorylation with different efficacy depending on their binding affinities. However, the tyrosine phosphorylation pattern and the activation of the major downstream signaling pathways were comparable. The maximal angiogenic effect stimulated by different VEGFR2 ligands was dependent on their ability to bind to co-receptor Neuropilin (Nrp), which was shown to form complexes with VEGFR2. The ability of these VEGFR2 ligands to induce vascular permeability was dependent on their concentration and VEGFR2 affinity, but not on Nrp binding. VEGFR2 activation alone is sufficient for inducing endothelial cell proliferation, formation of tube-like structures and vascular permeability. The level of VEGFR2 activation is dependent on the binding properties of the ligand used. However, closely similar activation pattern of the receptor kinase domain is seen with all VEGFR2 ligands. Nrp binding strengthens the angiogenic potency without increasing vascular permeability. This study sheds light on how different structurally closely related VEGFR2 ligands bind to and signal via VEGFR2/Nrp complex to induce angiogenesis and vascular permeability. The knowledge of this study could be used for designing VEGFR2/Nrp ligands with improved therapeutic properties.

Nieminen T ，Toivanen PI ，Rintanen N ，Heikura T ，Jauhiainen S ，Airenne KJ ，Alitalo K ，Marjomäki V ，Ylä-Herttuala S ... -  《-》

Vascular endothelial growth factor (VEGF)-A165b is a weak in vitro agonist for VEGF receptor-2 due to lack of coreceptor binding and deficient regulation of kinase activity.

Kawamura H ，Li X ，Harper SJ ，Bates DO ，Claesson-Welsh L ... -  《-》

Cryptotanshinone inhibits VEGF-induced angiogenesis by targeting the VEGFR2 signaling pathway.

Anti-angiogenesis has been proposed as an important strategy for angiogenesis-related diseases. Cryptotanshinone (CPT), an active component of Salvia miltiorrhiza, may be a potential inhibitor of angiogenesis. However, the molecular mechanisms underlying its anti-angiogenic activities remain poorly understood. This study is to investigate the effects of CPT on VEGF-induced angiogenesis and VEGFR2 signaling pathway in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with different concentration of CPT (5-20μmol/L) and the viability, endothelial cell migration, invasion, and tubular-like structure formation of HUVECs were detected by MTT, wound-healing migration, Transwell invasion and Matrigel tube formation assays, respectively. To assess the effect of CPT on VEGFR2 signaling pathway, VEGF-induced phosphorylation of VEGFR2 and its downstream molecules, including ERK1/2, p90RSK, Src and FAK were analyzed by Western blot. CPT significantly suppressed VEGF-induced cells proliferation, migration, invasion, and tubular-like structure formation in HUVECs in a dose- and time-dependent manner. Western blot results revealed that CPT significantly suppressed VEGF-induced phosphorylation of VEGFR2 and its key downstream protein kinases, including p-ERK1/2, p-p90RSK, pY416-Src and pY576/577-FAK, which are responsible for endothelial cell migration, proliferation, and survival. Our study suggested that CPT potently inhibits VEGF-induced angiogenesis by suppressing VEGFR2 activation and its downstream Src/FAK and ERK1/2 signaling pathways in HUVECs, highlighting the therapeutic potential for the treatment of angiogenesis-related diseases.

Xu X ，Wu L ，Zhou X ，Zhou N ，Zhuang Q ，Yang J ，Dai J ，Wang H ，Chen S ，Mao W ... -  《-》

VEGFR3 Modulates Vascular Permeability by Controlling VEGF/VEGFR2 Signaling.

Vascular endothelial growth factor (VEGF) is the main driver of angiogenesis and vascular permeability via VEGF receptor 2 (VEGFR2), whereas lymphangiogenesis signals are transduced by VEGFC/D via VEGFR3. VEGFR3 also regulates sprouting angiogenesis and blood vessel growth, but to what extent VEGFR3 signaling controls blood vessel permeability remains unknown. To investigate the role of VEGFR3 in the regulation of VEGF-induced vascular permeability. Long-term global Vegfr3 gene deletion in adult mice resulted in increased fibrinogen deposition in lungs and kidneys, indicating enhanced vascular leakage at the steady state. Short-term deletion of Vegfr3 in blood vascular endothelial cells increased baseline leakage in various tissues, as well as in tumors, and exacerbated vascular permeability in response to VEGF, administered via intradermal adenoviral delivery or through systemic injection of recombinant protein. VEGFR3 gene silencing upregulated VEGFR2 protein levels and phosphorylation in cultured endothelial cells. Consistent with elevated VEGFR2 activity, vascular endothelial cadherin showed reduced localization at endothelial cell-cell junctions in postnatal retinas after Vegfr3 deletion, or after VEGFR3 silencing in cultured endothelial cells. Furthermore, concurrent deletion of Vegfr2 prevented VEGF-induced excessive vascular leakage in mice lacking Vegfr3. VEGFR3 limits VEGFR2 expression and VEGF/VEGFR2 pathway activity in quiescent and angiogenic blood vascular endothelial cells, thereby preventing excessive vascular permeability.

Heinolainen K ，Karaman S ，D'Amico G ，Tammela T ，Sormunen R ，Eklund L ，Alitalo K ，Zarkada G ... -  《-》

Stanniocalcin-1 and -2 promote angiogenic sprouting in HUVECs via VEGF/VEGFR2 and angiopoietin signaling pathways.

The members of stanniocalcins (STCs: STC-1 and STC-2) family are known to be involved in tumor progression and metastasis. Although current evidences suggest the involvement of STCs in vascular biology, the functional roles of STCs in angiogenesis have not yet been elucidated. The objective of this study was to decipher the roles of STCs in angiogenesis of human umbilical vascular endothelial cells (HUVECs). We prepared STC1 or STC2 lentiviral particles to transduce the cells to reveal their effects on the processes of cell proliferation, migration and tube formation. The stimulatory effects of STCs on these processes were demonstrated, supporting the notion of STCs in angiogenesis. To dissect the molecular components involved, STC1 or STC2 transduction led to significant increases in the expression levels of cell cycle regulators (i.e. cyclin-D and phospho-retinoblastoma), matrix metalloproteinase (MMP)-2 but a decrease of tissue inhibitors of metalloproteases (TIMP)-1. The expression levels of the cell adhesion/junctional proteins vimentin and VE-cadherin, were significantly induced. Moreover the transduction induced both mRNA and protein levels of eNOS, VEGF and VEGFR2 (KDR mRNA and pKDR), highlighting the stimulatory effects of STCs on VEGF-signaling pathway. Furthermore STC2 transduction but not STC1, activated angiopoietin (Ang)-2 pathway. Taken together, STC1 and STC2 play positive roles in angiogenic sprouting. The action of STC1 was mediated via VEGF/VEGFR2 pathway while STC2 were mediated via VEGF/VEGFR2 and Ang-2 pathways.

Law AY ，Wong CK 《-》