新型酪氨酸激酶抑制剂XCF-43b体外抗血管新生研究

目的 探究XCF-43b 体外抗血管新生机理.方法 鸡胚尿囊膜(CAM)检测化合物抑制血管新生能力,MTT检测其对HUVEC细胞增殖影响,划痕实验和微管形成实验检测化合物对HUVEC迁移和微管形成的影响,Western印迹检测VEGFR2信号通路相关蛋白表达情况.结果 XCF-43b能够抑制CAM血管新生,抑制HUVEC细胞增殖的IC50为(28.42±7.23) μmol/L,对在VEGF刺激下的HUVEC的IC50值为(9.03±1.28) μmol/L,此外,2.5 μmol/L的XCF-43b能够抑制HUVEC细胞的迁移和微管形成;且能够抑制VEGFR2及其下游信号因子的激活.结论 XCF-43b通过抑制VEGFR2信号通路来抑制血管新生.     

Myricetin Inhibits Breast Tumor Growth and Angiogenesis by Regulating VEGF/VEGFR2 and p38MAPK Signaling Pathways

Tumor angiogenesis is an important cause of tumor growth and metastasis. Myricetin is a flavonoid component used in traditional Chinese medicine that has been demonstrated to have anticancer activity. However, to the best of our knowledge, the effect of myricetin on tumor angiogenesis remains unknown. The present study reports the identification of myricetin as a potential chemopreventive agent by reason of its inhibition of tumor angiogenesis and demonstrates the anticancer effects of myricetin in vivo. Cell Counting Kit-8 assays revealed that myricetin inhibits the proliferation of tumor cells but not that of human umbilical vein endothelial cells (HUVECs), and a transwell assay demonstrated that myricetin could inhibit the migration of HUVECs. A rat aortic ring assay revealed that myricetin could also affect the development of microvessels and the formation of vascular networks. Further, an ELISA showed that myricetin reduced the levels of vascular endothelial growth factor (VEGF) in vivo and in vitro. Western blot analysis indicated that myricetin could downregulate VEGFR2 and p38MAPK. Therefore, myricetin could significantly inhibit tumor angiogenesis and has potential as a chemopreventive agent because of its inhibition to angiogenesis. Anat Rec, 302:2186–2192, 2019. © 2019 American Association for Anatomy     

CAPE suppresses VEGFR-2 activation, and tumor neovascularization and growth

The growth and metastasis of human solid tumors and the development of conditions such as diabetic retinopathy, rheumatoid arthritis, inflammatory psoriasis, and others are regulated by the balance between angiogenic stimulators and inhibitors released in the angiogenic–pathological microenvironment. Vascular endothelial growth factor (VEGF), an angiogenic factor, is a potent endothelial-specific mitogen that activates endothelial cells in pathological angiogenesis. Recently, we demonstrated that caffeic acid phenethyl ester (CAPE) inhibits tumor growth, invasion, and metastasis. However, the precise molecular mechanism underlying the inhibitory effect of CAPE on VEGF-mediated angiogenesis remains unknown. Here, we show that CAPE suppressed VEGF-induced proliferation, tube formation, migration, the formation of actin stress fibers and loss of VE-cadherin at cell–cell contacts in endothelial cells, indicating the inhibition of VEGF-mediated VEGF receptor-2 (VEGFR-2) and its downstream signal activation in vitro. CAPE blocked VEGF-stimulated neovascularization in the Matrigel plugs assay, and reduced vascular permeability in mouse skin capillaries in vivo. CAPE inhibited the growth and neovascularization of primary tumor cells in C57BL/6 and BALB/c mice inoculated with Lewis lung carcinoma, colon carcinoma, and melanoma cells. These results suggest that CAPE negatively modulates VEGF-induced angiogenesis by suppressing VEGFR-2 activation, and might be a therapeutic avenue for anti-angiogenesis.     

Mesenchymal stem cells regulate angiogenesis according to their mechanical environment

In fracture and bone defect healing, MSCs largely drive tissue regeneration. MSCs have been shown to promote angiogenesis both in vivo and in vitro. Angiogenesis is a prerequisite to large tissue reconstitution. The present study investigated how mechanical loading of MSCs influences their proangiogenic capacity. The results show a significant enhancement of angiogenesis by conditioned media from mechanically stimulated compared with unstimulated MSCs in two-dimensional tube formation and three-dimensional spheroid sprouting assays. In particular, proliferation but not migration or adhesion of endothelial cells was elevated. Promotion of angiogenesis was dependent upon fibroblast growth factor receptor 1 (FGFR1) signaling. Moreover, stimulation of tube formation was inhibited by vascular endothelial growth factor receptor (VEGFR) tyrosine kinase blocking. Screening for the expression levels of different soluble regulators of angiogenesis revealed an enrichment of matrix metalloprotease 2, transforming growth factor beta1, and basic fibroblast growth factor but not of vascular endothelial growth factor in response to mechanical stimulation. In conclusion, mechanical loading of MSCs seems to result in a paracrine stimulation of angiogenesis, most likely by the regulation of a network of several angiogenic molecules. The underlying mechanism appears to be dependent on the FGFR and VEGFR signaling cascades and might be mediated by an additional cross-talk with other pathways.     

Silencing of CCR7 inhibits the growth,invasion and migration of prostate cancer cells induced by VEGFC

Early in prostate cancer development, tumor cells express vascular endothelial growth factor C (VEGF-C), a secreted molecule that is important in angiogenesis progression. CC-chemokine receptor 7 (CCR7), another protein involved in angiogenesis, is strongly expressed in most human cancers, where it activated promotes tumor growth as well as favoring tumor cell invasion and migration. The present study aimed to investigate the effect of down-regulating CCR7 expression on the growth of human prostate cancer cells stimulated by VEGFC. The CCR7-specific small interfering RNA (siRNA) plasmid vector was constructed and then transfected into prostate cancer cells. The expression of CCR7 mRNA and protein was detected by quantitative polymerase chain reaction and western blot analysis, respectively. Cell proliferation, apoptosis, cell cycle distribution and cell migration were assessed following knockdown of CCR7 by RNA interference (RNAi). Western blot analysis was used to identify differentially expressed angiogenesis- and cell cycle-associated proteins in cells with silenced CCR7. The expression levels of CCR7 in prostate cancer cells transfected with siRNA were decreased, leading to a significant inhibition of prostate cancer cell proliferation, migration and invasion induced by VEGFC. Western blot analysis revealed that silencing of CCR7 may inhibit vascular endothelial growth factor, matrix metalloproteinase (MMP)-2 and MMP-9 protein expression. In conclusion, the present study demonstrated that RNAi can effectively silence CCR7 gene expression and inhibit the growth of prostate cancer cells, which indicates that there is a potential of targeting CCR7 as a novel gene therapy approach for the treatment of prostate cancer.     

Cyclooxygenase inhibitors suppress angiogenesis and reduce tumor growth in vivo

Angiogenesis plays a key role in the development of malignant tumors. To clarify the roles of cyclooxygenase (COX) in malignant tumor development and angiogenesis, we investigated the effects of COX inhibitors on two kinds of gastrointestinal cancer xenograft, one of which overexpresses COX-2 and the other expresses no COX, in nude mice in vivo. There was a positive correlation between tumor volume and angiogenesis within the xenograft. Oral administration with a specific COX-2 or a nonspecific COX inhibitors lowered the expression of potent angiogenic factors; vascular endothelial growth factor and basic fibroblast growth factor, reduced angiogenesis and growth, induced apoptosis, and suppressed cell replication of the COX-2 overexpressing cancer xenografts in a dose-dependent manner. A nonspecific COX inhibitor, not a specific COX-2 inhibitor, reduced growth and angiogenesis of non-COX expressing cancer xenograft by inhibition of COX-1 in vascular endothelial cells. These results demonstrate that COX inhibitors suppress angiogenesis and tumor growth by inhibiting expression of angiogenic factors and vascular endothelial cell growth. They support the hypothesis that COX plays an important role in cancer growth via angiogenesis. These findings offer a new strategy against cancer using COX inhibitors (nonsteroidal anti-inflammatory drugs).     

Control of angiogenesis by VEGF and endostatin-encapsulated protein microcrystals and inhibition of tumor angiogenesis

Encapsulation of cytokines within protein microcrystals (polyhedra) is a promising approach for the stabilization and delivery of therapeutic proteins. Here, we investigate the influence of vascular endothelial growth factor (VEGF) microcrystals and endostatin microcrystals on angiogenesis. VEGF was successfully encapsulated into microcrystals derived from insect cypovirus with overexpression of protein disulfide bond isomerase. VEGF microcrystals were observed to increase the phosphorylation of p42/p44 MAP kinase and to stimulate the proliferation, migration, and network and tube formation of human umbilical vein endothelial cells (HUVECs). Endostatin was also successfully encapsulated into microcrystals. Endostatin microcrystals showed antiangiogenesis activities and inhibited the migration, and network and tube formation of HUVECs. Local administration of endostatin microcrystals in mice inhibited both angiogenesis and tumor growth with clear significant differences between treatment and control groups. Endostatin microcrystals only affected angiogenesis, but had no significant effect on lymphangiogenesis compared to controls. Local therapy using endostatin microcrystals offers a potential approach to achieve sustained therapeutic release of antiangiogenic molecules for cancer treatment.     

Gamma-secretase inhibitor DAPT suppresses glioblastoma growth via uncoupling of tumor vessel density from vessel function

The objective of the current study was to investigate the regulation of VEGF signaling and tumor angiogenesis by gamma-secretase inhibitor DAPT in glioblastoma. Effects of DAPT on VEGFR1, VEGFR2, endothelial cell proliferation and vessel function were evaluated using mouse microvascular endothelial H5V cell line and U87MG xenograft mouse models. We found that DAPT efficiently inhibited Notch signaling, increased VEGFR2 expression, but decreased VEGFR1 expression. DAPT treatment enhanced endothelial cell proliferation when used combined with VEGF, but exerted no effect if used alone. In U87MG xenograft mouse models, DAPT treatment increased tumor vessel density but compromised vessel function, as evidenced by poor perfusion and aggravated hypoxia. Therefore, DAPT treatment results in an uncoupling of tumor vessel density from vessel function and suppresses glioblastoma growth; disturbance of angiogenesis with DAPT presents a novel therapeutic approach for glioblastoma.     

重组人信号素3A抑制胃癌血管生成及其机制

目的 探讨信号素3A（Sema3A）及其受体神经激-1（NRP-1）在胃癌中的表达及其与微血管密度（MVD）的相关性;并探讨重组人Sema3A对胃癌血管生成的影响及其相关的机制。方法 选取40例手术切除胃癌组织及其癌旁正常组织,免疫组织化学法检测组织中Sema3A、NRP-1的表达及MVD。ELISA检测胃癌患者组及正常对照组血清Sema3A的表达水平。Western blotting检测5株胃癌细胞系（MGC-803、HGC-27、MKN-28、SGC-7901、MKN-45）、人正常胃黏膜细胞（GES-1）中Sema3A和NRP-1的表达。应用Transwell小室构建非接触式体外共培养体系,小管形成实验初步研究不同浓度重组人Sema3A对胃癌血管生成的影响;Western blotting检测共培养体系中血管内皮生长因子受体2（VEGFR2）、NRP-1的表达水平。结果 胃癌组织、细胞和患者血清中Sema3A的表达显著低于对照组（P<0.05）,胃癌组织和MKN 28细胞中的NRP-1表达明显升高（P<0.05）,两者均与胃癌TNM分期相关（P<0.05）,且Sema3A与微血管密度存在负相关（P<0.05）。在体外共培养体系中,重组人Sema3A处理组人脐静脉内皮细胞（HUVEC）小管形成能力下降,且具有浓度依赖性;重组人Sema3A可下调VEGFR2蛋白的表达。结论 Sema3A在胃癌组织、细胞和患者血清中均表达降低,与微血管密度成负相关,重组人Sema3A具有体外抑制胃癌血管生成的作用,可能与下调VEGFR2蛋白表达有关。     

携带pGRIM-19-si-survivin共表达质粒的减毒沙门菌对前列腺癌移植瘤的体内抑制作用

目的:探讨人减毒沙门菌携带pGRIM-19-si-survivin共表达质粒对人前列腺癌皮下移植瘤生长的抑制作用及相关机制。方法:复制裸鼠前列腺癌皮下移植瘤模型,通过腹腔注射携带共表达质粒的减毒沙门菌进行治疗,实时监测肿瘤体积;运用免疫组织化学染色法、RT-PCR法和TUNEL法检测携带pGRIM-19-si-survivin共表达质粒的减毒沙门菌对肿瘤抑制作用的相关机制。结果:与psi-survivin或pGRIM-19单基因治疗对照组比较,携带pGRIM-19-si-survivin共表达质粒减毒沙门菌组肿瘤体积明显缩小,其缩小率分别约为2.36和3.02倍;肿瘤组织内survivin mRNA及蛋白表达明显下降(P0.05),GRIM-19 mRNA及蛋白表达明显增高(P0.05),凋亡相关蛋白Bcl-xL、Stat3、cyclin D1和c-Myc的mRNA表达明显降低(P0.05),血管内皮生长因子(VEGF)mRNA及Ki67蛋白表达降低而caspase-3 mRNA表达明显上调(P0.05),同时细胞凋亡明显。结论:携带pGRIM-19-si-survivin共表达质粒的减毒沙门菌明显抑制裸鼠前列腺癌皮下移植瘤的生长,其发生机制与促进细胞凋亡及抑制肿瘤细胞增殖有关。     

Antiangiogenic properties of silver nanoparticles

Angiogenesis is an important phenomenon involved in normal growth and wound healing processes. An imbalance of the growth factors involved in this process, however, causes the acceleration of several diseases including malignant, ocular, and inflammatory diseases. Inhibiting angiogenesis through interfering in its pathway is a promising methodology to hinder the progression of these diseases. The function and mechanism of silver nanoparticles (Ag-NPs) in angiogenesis have not been elucidated to date. PEDF is suggested to be a potent anti-angiogenic agent. In this study, we postulated that Ag-NPs might have the ability to inhibit angiogenesis, the pivotal step in tumor growth, invasiveness, and metastasis. We have demonstrated that Ag-NPs could also inhibit vascular endothelial growth factor (VEGF) induced cell proliferation, migration, and capillary-like tube formation of bovine retinal endothelial cells like PEDF. In addition, Ag-NPs effectively inhibited the formation of new blood microvessels induced by VEGF in the mouse Matrigel plug assay. To understand the underlying mechanism of Ag-NPs on the inhibitory effect of angiogenesis, we showed that Ag-NPs could inhibit the activation of PI3K/Akt. Together, our results indicate that Ag-NPs can act as an anti-angiogenic molecule by targeting the activation of PI3K/Akt signaling pathways.     

Triptolide Suppresses Alkali Burn‐Induced Corneal Angiogenesis Along with a Downregulation of VEGFA and VEGFC Expression

Triptolide (TPL) is an active compound extracted from a Chinese herbal medicine tripterygium wilfordii Hook. f. (Celastraceae), which has been used as an anti‐inflammatory drug for years. It also inhibits the growth and proliferation of different types of cancer cells. The inhibitory effect of TPL on angiogenesis after chemical‐induced corneal inflammation was studied in vivo. The effects of TPL on the proliferation, apoptosis, migration, and tube formation of rat aortic endothelial cells (RAECs) were studied in vitro. Cell proliferation and apoptosis were measured by MTT assay and flow cytometry, respectively. Migration was analyzed using the scratch wound healing assay and transwell assay. Tube formation assay was used to examine angiogenesis. Real‐time PCR and Western blot were used to determine the expression of vascular endothelial growth factor A (VEGFA) and VEGFC. To study the in vivo effects of TPL, the mouse model of alkali burn‐induced corneal angiogenesis was used. The angiogenesis was analyzed by determining the density of the newly generated blood vessels in corneas. We found that TPL induced apoptosis and inhibited the proliferation of RAECs in a dose‐dependent manner. TPL inhibited migration and tube formation of RAECs and decreased the expression of VEGFA and VEGFC in vitro. Furthermore, TPL suppressed alkali burn‐induced corneal angiogenesis and inhibited the expression of VEGFA and VEGFC in corneas in vivo. In conclusion, topical TPL as a pharmacological agent has the ability to reduce angiogenesis in cornea and may have clinical indications for the treatment of corneal angiogenesis diseases which have to be further explored. Anat Rec, 300:1348–1355, 2017. © 2017 Wiley Periodicals, Inc.     

Des-γ-carboxy prothrombin stimulates human vascular endothelial cell growth and migration

Des-γ-carboxy prothrombin (DCP) is an aberrant prothrombin produced by hepatocellular carcinoma (HCC) cells. Serum and tissue DCP expressions are thought to reflect the biological malignant potential of HCC. However, the role of DCP in the development of angiogenesis is not well understood. Herein, we report the effects of DCP on growth and migration of human vascular endothelial cells. DCP significantly stimulated the proliferation of HUVEC (ECV304) cells in a dose and time dependent manner, as measured by the MTT assay. A continuous rapid migration of ECV304 cells was observed in the presence of DCP measured by the scratch wound assay. The continuous rapid invasive activity, measured by transwell chamber assay also showed that DCP increased endothelial cells migration through the reconstituted extracellular matrix (Matrigel). Further, the tube formation of vascular endothelial cells on 3-D Matrigel showed an increased number of branch points of ECV304 cells induced by DCP in a dose dependent manner. The levels of vascular endothelial cell growth-related angiogenic factors and matrix metalloproteinase were also examined. DCP significantly stimulated the expression levels of epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), and matrix metalloproteinase (MMP)-2 (latent and active). Together, these data suggest that DCP is a novel type of vascular endothelial growth factor that possesses potent mitogenic and migrative activities in angiogenesis of HCC. S. Cui and X.-J. Qu contributed equally to this work.     

Inhibition of VEGFR2 prevents DMBA-induced mammary tumor formation

Preinvasive mammary pathologies in humans and rat chemical carcinogenesis model systems have an increased microvascular density relative to normal tissue. This suggests the possibility of preventing invasive breast cancer by inhibiting angiogenesis. Vascular endothelial cell growth factor (VEGF) is a potent angiogenic growth factor, commonly involved in tumor-induced angiogenesis. Here, we show that both VEGF and VEGFR2 expression increase with histological progression to invasive disease in the rat 7,12-dimethylbenz[a]anthracene (DMBA) model. Other VEGF receptors, VEGFR1, neuropilin 1 and neuropilin 2, are constitutively expressed throughout progression. To examine whether VEGF signaling is functionally relevant to tumor-induced endothelial tubule formation in vitro and for tumor formation in vivo, we utilized the VEGFR2 inhibitor, ZD6474. In vitro endothelial cell tubulogenesis induced by isolated mammary organoids or carcinoma in situ from DMBA-treated rats is inhibited by ZD6474, in a dose-dependent fashion. The administration of ZD6474 to DMBA-treated rats inhibits the formation of atypical ductal hyperplasia and carcinoma in situ by greater than 95% (P < 0.05), when administered 1 week or 6 weeks post-DMBA initiation. Invasive disease was absent in all ZD6474 cohorts. These data support the hypothesis that progression of DMBA-induced preinvasive mammary pathologies to palpable disease requires angiogenesis via a VEGF-dependent mechanism.     

EphrinA1 inhibits vascular endothelial growth factor-induced intracellular signaling and suppresses retinal neovascularization and blood-retinal barrier breakdown

The Eph receptor/ephrin system is a recently discovered regulator of vascular development during embryogenesis. Activation of EphA2, one of the Eph receptors, reportedly suppresses cell proliferation and adhesion in a wide range of cell types, including vascular endothelial cells. Vascular endothelial growth factor (VEGF) plays a primary role in both pathological angiogenesis and abnormal vascular leakage in diabetic retinopathy. In the study described herein, we demonstrated that EphA2 stimulation by ephrinA1 in cultured bovine retinal endothelial cells inhibits VEGF-induced VEGFR2 receptor phosphorylation and its downstream signaling cascades, including PKC (protein kinase C)-ERK (extracellular signal-regulated kinase) 1/2 and Akt. This inhibition resulted in the reduction of VEGF-induced angiogenic cell activity, including migration, tube formation, and cellular proliferation. These inhibitory effects were further confirmed in animal models. Intraocular injection of ephrinA1 suppressed ischemic retinal neovascularization in a dose-dependent manner in a mouse model. At a dose of 125 ng/eye, the inhibition was 36.0 +/- 14.9% (P < 0.001). EphrinA1 also inhibited VEGF-induced retinal vascular permeability in a rat model by 46.0 +/- 10.0% (P < 0.05). These findings suggest a novel therapeutic potential for EphA2/ephrinA1 in the treatment of neovascularization and vasopermeability abnormalities in diabetic retinopathy.     

Targeting the EGFR, VEGFR, and PDGFR on colon cancer cells and stromal cells is required for therapy

Immunohistochemical analysis of human colon cancers growing in the cecal walls of nude mice revealed that epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor 2 (VEGFR2) were expressed by different tumor cells and tumor-associated endothelial cells, whereas platelet-derived growth factor receptor (PDGFR)beta was expressed by tumor-associated endothelial cells and pericytes. We hypothesized that treatment of nude mice with AEE788 (an inhibitor of EGFR and VEGFR phosphorylation) and STI571 (an inhibitor of PDGFRbeta phosphorylation) combined with irinotecan would overcome the intratumoral heterogeneity of these growth factors and efficiently inhibit colon cancer growth and metastasis. We implanted HT29 and KM12SM cells into the cecal walls of nude mice. Two weeks later, the mice were treated with oral vehicle solution; oral AEE788, oral STI571, or intraperitoneal injection of irinotecan as single agents; or the various combinations of these agents. We then assessed the mice for tumor growth and metastasis. Immunohistochemical analyses revealed that oral AEE788 suppressed proliferation and increased apoptosis of tumor cells and tumor-associated endothelial cells. Oral STI571 increased apoptosis of tumor-associated endothelial cells and pericytes. The combination of AEE788, STI571, and irinotecan produced the greatest inhibition of primary tumor growth and metastasis. Collectively, these data demonstrate that only targeting multiple tyrosine kinase receptors on colon cancer cells and tumor-associated stromal cells can overcome the effects of biologic heterogeneity for resistance to treatment and has the potential to improve therapeutic outcome for patients with this disease.     

TRPV3 promotes the angiogenesis through HIF-1α-VEGF signaling pathway in A549 cells

BackgroundAngiogenesis is an essential physiological process in the growth and metastasis of primary tumors. Ca²⁺ signaling is crucial for tumor angiogenesis. The purpose of this study was to detect the potential role of Ca²⁺ permeable transient receptor potential vanilloid-3 (TRPV3) in the angiogenesis of non-small cell lung cancer (NSCLC).MethodsSmall interfering RNA was used to down-regulate TRPV3 expression in A549 cells. A laser scanning confocal microscope was used to examine intracellular calcium concentration ([Ca²⁺]i). Human umbilical vein endothelial cells (HUVECs) tube formation and migration assay, Western blot, MTT and ELISA were performed to detect the potential mechanisms of TRPV3 in tumor angiogenesis. A mouse tumor xenograft model was performed to expound the effects of TRPV3 on tumor cell growth.ResultsInhibition of TRPV3 reduced [Ca²⁺]i and protein expressions of VEGF and HIF-1α in A549 cells. Moreover, HIF-1α depletion decreased the secretion and expression of VEGF. Depletion of TRPV3 inhibited HUVECs proliferation, tube formation and migration induced by conditioned medium. And TRPV3 inhibition could decrease the volume of xenograft tumors and MVD of CD34⁺ cells. The expression levels of HIF-1α, VEGF and p-CaMKП in the xenograft tumors in RuR and siTRPV3 groups was reduced.ConclusionsTRPV3 calcium channel protein may play a key role in NSCLC angiogenesis. TRPV3 could promote the angiogenesis through HIF-1α-VEGF signaling pathway. Targeting TRPV3 channel protein by novel approaches would be useful for reversing NSCLC angiogenesis.     

Antiangiogenic Activity of Acer tegmentosum Maxim Water Extract in Vitro and in Vivo

Angiogenesis, the formation of new blood vessels, is critical for tumor growth and metastasis. Notably, tumors themselves can lead to angiogenesis by inducing vascular endothelial growth factor (VEGF), which is one of the most potent angiogenic factors. Inhibition of angiogenesis is currently perceived as one of the most promising strategies for the blockage of tumor growth. In this study, we investigated the effects of Acer tegmentosum maxim water extract (ATME) on angiogenesis and its underlying signal mechanism. We studied the antiangiogenic activity of ATME by using human umbilical vein endothelial cells (HUVECs). ATME strongly inhibited VEGF-induced endothelial cell proliferation, migration, invasion, and tube formation, as well as vessel sprouting in a rat aortic ring sprouting assay. Moreover, we found that the p44/42 mitogen activated protein (MAP) kinase signaling pathway is involved in the inhibition of angiogenesis by ATME. Moreover, when we performed the in vivo matrigel plug assay, VEGF-induced angiogenesis was potently reduced when compared to that for the control group. Taken together, these results suggest that ATME exhibits potent antiangiogenic activity in vivo and in vitro and that these effects are regulated by the extracellular regulated kinase (ERK) pathway.

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Vascular endothelial growth factor (VEGF)-Receptor2: its biological functions, major signaling pathway, and specific ligand VEGF-E.

Two high-affinity receptors for vascular endothelial growth factor (VEGF)-A, VEGFR1 and VEGFR2, cooperate for physiological vasculogenesis and angiogenesis in embryogenesis. VEGFR2 transduces the major signals for angiogenesis via its strong tyrosine kinase activity. However, unlike other representative tyrosine kinase receptors, VEGFR2 does not use the Ras pathway as a major downstream signaling but rather uses the phospholipase C-protein kinase C pathway to signal mitogen-activated protein (MAP)-kinase activation and DNA synthesis. Cell migration signals from VEGFR2 were recently shown to use, at least partly, a pathway dependent on the adaptor molecule TSAd from the kinase-insert region of VEGFR2. VEGFR2 is a direct and major signal transducer for pathological angiogenesis, including cancer and diabetic retinopathy, in cooperation with many other signaling partners; thus, VEGFR2 and its downstream signaling appear to be critical targets for the suppression of these diseases. More than 10 antagonists of VEGFR2, including kinase inhibitors and neutralizing antibodies, are now under clinical trials. Recently, the VEGFR2-specific ligand VEGF-E (also known as Orf-VEGF) family was extensively characterized. Interestingly, activation of VEGFR2 via VEGF-E in vivo results in a strong angiogenic response in mice, with minor effects on inflammation and hypervascular permeability compared with VEGF-A, suggesting that VEGF-E is a useful tool for proangiogenic therapy in ischemic diseases.