Cyclooxygenase-2 promotes angiogenesis by increasing vascular endothelial growth factor and predicts prognosis in gallbladder carcinoma

AIM: To investigate the relationships between the expression of cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF) and the degree of vascularization, clinicopathologic feature, survival time of patients with gallbladder carcinomas. METHODS: Sixty-four gallbladder carcinoma specimens were evaluated for COX-2, VEGF expression by immunohi stochemical methods. Microvessel counts (MVC) were determined using CD34. The relationships between COX-2, VEGF expression, CD34-stained MVC, clinicopathologic features and survival time were analyzed. The correlations between COX-2 and VEGF expression, CD34-stained MVC were also investigated. RESULTS: COX-2, VEGF immunoreactivity were observed in 71.9% (46/64) and 54.7% (35/64) specimens, respectively. The average MVC in 64 cases of gallbladder carcinoma was 57±14 per high power vision field. The status of MVC was closely correlated with Nevin staging, tumor differentiation and lymph node metastasis (P<0.01, 0.002, and 0.003, 0.000, respectively). Increased VEGF expression was significantly correlated with tumor differentiation (poorly and moderately>well differentiated, P<0.05, P = 0.016). Clinical stages had no relation with the expression of VEGF (P>0.05, P = 0.612). There was a positive correlation between COX-2 expression and clinical stages. The positive rate of COX-2 was higher in cases of Nevin stages S4-S5 (81.8%) than in those of Nevin stages S1-S3 (50.0%) with a statistical significance (P0.01, P = 0.009). The expression of COX-2 did not vary with differentiation (P>0.05, P= 0.067). Statistically significant differences were also observed according to lymph node metastasis, COX-2 expression and VEGF expression (P<0.01,0.000, and 0.001, respectively). There was no relation between VEGF, COX-2 expression, MVC and the age and sex of patients. MVC and VEGF positive rate in the COX-2 positive gallbladder carcinoma tissue was higher than that in the COX-2 negative tissue (P<0.05, 0.000, and 0.032, respectively). Patients with VEGF, COX-2 positive tumors had a significantly shorter survival time than those with negative tumors (P<0.05,0.004, 0.01, respectively). CONCLUSION: Augmented tumor neovascularization induced by VEGF may be one of the several effects of COX-2 responsible for poor prognosis of human gallbladder carcinoma. COX-2 inhibitor, either in combination therapy with other agents, or for chemoprevention, may be effective via suppression of angiogenesis in this fatal disease.     

Ccm1 regulates microvascular morphogenesis during angiogenesis

Cerebral cavernous malformations (CCMs) are characterized by abnormally dilated intracranial capillaries that have a propensity to bleed. The development of some CCMs in humans has been attributed to mutations in CCM1 and CCM2 genes. In animal models, major cardiovascular defects caused by both gene mutations have been observed. However, the effects of the loss of Ccm function on the microvasculature in animal models are less defined. Using high-resolution imaging in vivo, we demonstrated that the loss of Ccm1 in zebrafish embryos leads to failed microvascular lumenization during angiogenesis due to impaired intraendothelial vacuole formation and fusion. No developmental changes during vasculogenesis and the initial stage of angiogenesis were observed, being in contrast to prior reports. In vivo zebrafish studies were further substantiated by in vitro findings in human endothelial cells that elucidated the biochemical pathways of CCM1 deficiency. We found that CCM1 regulates angiogenic microvascular lumen formation through Rac1 small GTPase. In summary, Ccm1 has been identified as a key angiogenic modulator in microvascular tubulogenesis. Additionally, the microvascular pathology observed in developing Ccm1 mutant zebrafish embryos mirrors that seen in human CCM lesions, suggesting that zebrafish might provide a superior animal model to study the pathogenesis of human CCM.     

Interleukin-17 promotes angiogenesis and tumor growth

Interleukin-17 (IL-17) is a CD4 T-cell-derived proinflammatory cytokine. We investigated the effects of locally produced IL-17 by tumors as a means to evaluate its biologic function. Although recombinant IL-17 protein or retroviral transduction of IL-17 gene into tumors did not affect in vitro proliferation, IL-17 transfectants grew more rapidly in vivo when compared with controls. Immunostaining for Factor VIII revealed that tumors transduced with IL-17 had significantly higher vascular density when compared with controls. IL-17 indeed elicited neovascularization in rat cornea. In addition, angiogenic activity present in the conditioned media of CD4 T cells was markedly suppressed by neutralizing monoclonal antibody to IL-17. IL-17 had no direct effect on the growth of vascular endothelial cells, whereas IL-17 significantly stimulated migration. IL-17 also markedly promoted the cord formation of vascular endothelial cells. In addition, IL-17 up-regulated elaboration of a variety of proangiogenic factors by fibroblasts as well as tumor cells. These findings reveal a novel role for IL-17 as a CD4 T-cell-derived mediator of angiogenesis that stimulates vascular endothelial cell migration and cord formation and regulates production of a variety of proangiogenic factors. Furthermore, they suggest that inhibition of biologic action of IL-17 may have therapeutic benefits when applied to angiogenesis-related disorders.     

MicroRNA-378 promotes cell survival, tumor growth, and angiogenesis by targeting SuFu and Fus-1 expression

MicroRNAs are single-stranded RNA of 18-24 nt expressed endogenously that play important roles in cancer development. Here, we show that expression of miR-378 enhances cell survival, reduces caspase-3 activity, and promotes tumor growth and angiogenesis. Proteomic analysis indicates reduced expression of suppressor of fused (Sufu), a potential target of miR-378, which was confirmed in vitro and in vivo. Expression of a luciferase construct containing the target site in Sufu was repressed when cotransfected with miR-378. Transfection of a Sufu construct reversed the effect of miR-378, suggesting an important role for miR-378 in tumor cell survival. We also discovered that miR-378 targets Fus-1. Expression of luciferase constructs harboring the target sites in Fus-1 was repressed by miR-378. Fus-1 constructs with or without its 3' UTR were also generated. Cotransfection experiments showed that the presence of miR-378 repressed Fus-1 expression. Suppression of Fus-1 expression by siRNA against Fus-1 enhanced cell survival. Transfection of the Fus-1 construct reversed the function of miR-378 in cell survival. Our results suggest that miR-378 transfection enhanced cell survival, tumor growth, and angiogenesis through repression of the expression of two tumor suppressors, Sufu and Fus-1.     

Plexin-A4 promotes tumor progression and tumor angiogenesis by enhancement of VEGF and bFGF signaling

Plexin-A4 is a receptor for sema6A and sema6B and associates with neuropilins to transduce signals of class-3 semaphorins. We observed that plexin-A1 and plexin-A4 are required simultaneously for transduction of inhibitory sema3A signals and that they form complexes. Unexpectedly, inhibition of plexin-A1 or plexin-A4 expression in endothelial cells using specific shRNAs resulted in prominent plexin type specific rearrangements of the actin cytoskeleton that were accompanied by inhibition of bFGF and VEGF-induced cell proliferation. The two responses were not interdependent since silencing plexin-A4 in U87MG glioblastoma cells inhibited cell proliferation and strongly inhibited the formation of tumors from these cells without affecting cytoskeletal organization. Plexin-A4 formed stable complexes with the FGFR1 and VEGFR-2 tyrosine-kinase receptors and enhanced VEGF-induced VEGFR-2 phosphorylation in endothelial cells as well as bFGF-induced cell proliferation. We also obtained evidence suggesting that some of the pro-proliferative effects of plexin-A4 are due to transduction of autocrine sema6B-induced pro-proliferative signals, since silencing sema6B expression in endothelial cells and in U87MG cells mimicked the effects of plexin-A4 silencing and also inhibited tumor formation from the U87MG cells. Our results suggest that plexin-A4 may represent a target for the development of novel anti-angiogenic and anti-tumorigenic drugs.     

IL-17A通过增强肿瘤血管生成和侵袭促进肿瘤发展

目的探讨IL-17A在非小细胞肺癌血管形成和侵袭中的作用。方法Lewis肺癌细胞（LLC）在不同浓度IL-17A（0、25、50、100和200μg／L）条件下行增殖实验,LLC在50μg／L IL-17A和0μg／LIL-17A刺激下行侵袭实验。LLC在IL-17A刺激不同时间点下用实时定量PCR（RT—PCR）测定血管内皮生长因子-A（VEGF—A）、血管生成素-2（Ang-2）、基质金属蛋白酶-2（MMP-2）、MMP-9mRNA表达。C57BL／6小鼠接种LLC后随机分为3组,每组6只,分别予以瘤内注射PBS、对照腺病毒（Ad—NC）和干扰腺病毒（Ad—si—IL-17a,IL-17a基因沉默）,16d后处死小鼠,提取肿瘤组织RNA,RT-PCR检测VEGF-A、Ang-2、MMP-2和MMP-9mRNA表达。结果体外培养条件下IL-17A对肿瘤细胞的增殖能力没有影响,与无IL-17A组相比,50μg／L浓度的IL-17A组的肿瘤细胞VEGF-A、Ang-2、MMP-2和MMP-9mRNA表达水平明显升高,且肿瘤细胞侵袭能力增强（P〈0．01）。Ad—si—IL-17a组小鼠在13d（P〈0．05）和16d（P〈0．01）时肿瘤明显小于Ad-NC组和PBS组。Ad-si-IL-17a组肿瘤VEGF-A、Ang-2、MMP-2和MMP-9ITIRNA表达水平低于Ad—NC组和PBS组。结论靶向IL-17A的治疗可能为肿瘤治疗提供新思路。     

The Arf tumor suppressor gene promotes hyaloid vascular regression during mouse eye development

A key tumor suppressor mechanism that is disrupted frequently in human cancer involves the ARF and p53 genes. In mouse fibroblasts, the Arf gene product responds to abnormal mitogenic signals to activate p53 and trigger either cell cycle arrest or apoptosis. Recent evidence indicates that Arf also has p53-independent functions that may contribute to its tumor suppressor activity. Using Arf(-/-) and p53(-/-) mice, we have discovered a p53-independent requirement for Arf in the developmental regression of the hyaloid vascular system (HVS) in the mouse eye. Arf is expressed in the vitreous of the eye and is induced before HVS regression in the first postnatal week. In the absence of Arf, failed HVS regression causes a pathological process that resembles persistent hyperplastic primary vitreous, a developmental human eye disease thought to have a genetic basis. These findings demonstrate an essential and unexpected role for Arf during mouse eye development, provide insights into the potential genetic basis for persistent hyperplastic primary vitreous, and indicate that Arf regulates vascular regression in a p53-independent manner. The latter finding raises the possibility that Arf may function as a tumor suppressor at least in part by regulating tumor angiogenesis.     

VEGF and FGF prime vascular tube morphogenesis and sprouting directed by hematopoietic stem cell cytokines

Here, we demonstrate a novel, direct-acting, and synergistic role for 3 hematopoietic stem cell cytokines: stem cell factor, interleukin-3, and stromal derived factor-1α, in controlling human endothelial cell (EC) tube morphogenesis, sprouting, and pericyte-induced tube maturation under defined serum-free conditions in 3-dimensional matrices. Angiogenic cytokines such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) alone or VEGF/FGF combinations do not support these responses. In contrast, VEGF and FGF prime EC responses to hematopoietic cytokines via up-regulation of c-Kit, IL-3Rα, and C-X-C chemokine receptor type 4 from either human ECs or embryonic quail vessel explants. In support of these findings, EC Runx1 is demonstrated to be critical in coordinating vascular morphogenic responses by controlling hematopoietic cytokine receptor expression. Combined blockade of hematopoietic cytokines or their receptors in vivo leads to blockade of developmental vascularization in quail embryos manifested by vascular hemorrhage and disrupted vascular remodeling events in multiple tissue beds. This work demonstrates a unique role for hematopoietic stem cell cytokines in vascular tube morphogenesis and sprouting and further demonstrates a novel upstream priming role for VEGF and FGF to facilitate the action of promorphogenic hematopoietic cytokines.     

Autocrine human growth hormone promotes tumor angiogenesis in mammary carcinoma

Accumulating literature implicates pathological angiogenesis and lymphangiogenesis as playing key roles in tumor progression. Autocrine human growth hormone (hGH) is a wild-type orthotopically expressed oncogene for the human mammary epithelial cell. Herein we demonstrate that autocrine hGH expression in the human mammary carcinoma cell line MCF-7 stimulated the survival, proliferation, migration, and invasion of a human microvascular endothelial cell line (HMEC-1). Autocrine/paracrine hGH secreted from mammary carcinoma cells also promoted HMEC-1 in vitro tube formation as a consequence of increased vascular endothelial growth factor-A (VEGF-A) expression. Semiquantitative RT-PCR analysis demonstrated that HMEC-1 cells express both hGH and the hGH receptor (hGHR). Functional antagonism of HMEC-1-derived hGH reduced HMEC-1 survival, proliferation, migration/invasion, and tube formation in vitro. Autocrine/paracrine hGH secreted by mammary carcinoma cells increased tumor blood and lymphatic microvessel density in a xenograft model of human mammary carcinoma. Autocrine hGH is therefore a potential master regulator of tumor neovascularization, coordinating two critical processes in mammary neoplastic progression, angiogenesis and lymphangiogenesis. Consideration of hGH antagonism to inhibit angiogenic processes in mammary carcinoma is therefore warranted.     

Intussusceptive angiogenesis and its role in vascular morphogenesis, patterning, and remodeling

New blood vessels arise initially as blood islands in the process known as vasculogenesis or as new capillary segments produced through angiogenesis. Angiogenesis itself encompasses two broad processes, namely sprouting (SA) and intussusceptive (IA) angiogenesis. Primordial capillary plexuses expand through both SA and IA, but subsequent growth and remodeling are achieved through IA. The latter process proceeds through transluminal tissue pillar formation and subsequent vascular splitting, and the direction taken by the pillars delineates IA into overt phases, namely: intussusceptive microvascular growth, intussusceptive arborization, and intussusceptive branching remodeling. Intussusceptive microvascular growth circumscribes the process of initiation of pillar formation and their subsequent expansion with the result that the capillary surface area is greatly enhanced. In contrast, intussusceptive arborization entails formation of serried pillars that remodel the disorganized vascular meshwork into the typical tree-like arrangement. Optimization of local vascular branching geometry occurs through intussusceptive branching remodeling so that the vasculature is remodeled to meet the local demand. In addition, IA is important in creation of the local organ-specific angioarchitecture. While hemodynamic forces have proven direct effects on IA, with increase in blood flow resulting in initiation of pillars, the preponderant mechanisms are unclear. Molecular control of IA has so far not been unequivocally elucidated but interplay among several factors is probably involved. Future investigations are strongly encouraged to focus on interactions among angiogenic growth factors, angiopoetins, and related receptors.     

经导管动脉栓塞对肝癌血管生成的影响

目的:探讨肝癌经导管动脉栓塞(transcatheter arterial embolization,TAE)对残存肿瘤血管生成的影响.方法:建立20只兔Vχ2肝癌模型.TAE处理组(n=10),接受150-250μm聚乙烯醇经导管肝动脉栓塞;对照组(n=10),接受蒸馏水经导管肝动脉注入模拟TAE.栓塞后6 h或3 d.处死实验兔进行肿瘤组织取样,采用免疫组织化学方法评价样本的血管内皮生长因子(vascular endothelial growth facto,VEGF)蛋白表达和微血管密度(microvessel density,MVD),微血管标记采用CD31抗体,实时PCR检测VEGFmRNA表达.结果:TAE处理组肿瘤呈不完全性中央坏死,结果:TAE处理组肿瘤呈不完全性中央坏死,坏死区周围可见肿瘤细胞存活.TAE处理组肿瘤的VEGF蛋白、mRNA水平和平均MVD均显著高于对照组(P=0.001,0.000,0.001).VEGF蛋白水平与MVD呈显著性正相关(r=0.677,P=0.001).结论:肝癌TAE可激活残存肿瘤血管生成,VEGF在TAE相关性血管生成中发挥重要调节作用.     

Regulation of endothelial cell survival and apoptosis during angiogenesis

The process of angiogenesis plays an important role in many physiological and pathological conditions. Inhibition of endothelial cell (EC) apoptosis providing EC survival is thought to be an essential mechanism during angiogenesis. Many of the angiogenic growth factors inhibit EC apoptosis. In addition, the adhesion of ECs to the extracellular matrix or intercellular adhesion promotes EC survival. In contrast, increasing evidence suggests that the induction of EC apoptosis may counteract angiogenesis. In this review, we focus on the regulation of EC survival and apoptosis during angiogenesis and especially on the effects and intracellular signaling promoted by angiogenic growth factors, endogenous angiogenic inhibitors (such as angiostatin, endostatin, and thrombospondin-1), and the adhesion to the extracellular matrix. Furthermore, we discuss the effects of cross talk between adhesion molecules and growth factors. Understanding the molecular mechanisms involved in the regulation of EC survival and apoptosis may provide new targets for the development of new therapies to enhance angiogenesis in the case of tissue-ischemia (eg, the neovascularization of myocardium) or to inhibit angiogenesis in the case of neovascularization-dependent disease (eg, tumor, diabetic retinopathy).     

miR-320 regulates tumor angiogenesis driven by vascular endothelial cells in oral cancer by silencing neuropilin 1

Tumor angiogenesis is a critical process during cancer progression that modulates tumor growth and metastasis. Here, we identified an anti-angiogenic microRNA, miR-320, which is decreased in oral squamous cell carcinoma (OSCC) cell lines and tumor tissues from OSCC patients, down-regulated in blood vessels and inversely correlated with vascularity in OSCC tissues. Neuropilin 1 (NRP1), an important regulator of angiogenesis, was found to be a target of miR-320. The 3′-untranslated region of NRP1 mRNA contains multiple miR-320 binding sites, and its expression was regulated by miR-320. By administering either miR-320 precursor or antagonist, we found that miR-320 suppressed the migration, adhesion and tube formation of vascular endothelial cells. Knockdown of NRP1 abolished antagomiR-320-induced cell migration. Additionally, miR-320 expression was regulated by hypoxia in growth factor-deficient conditions by the hypoxia-inducible factor 1-alpha. Furthermore, lentivirus carrying the miR-320 precursor suppressed the tumorigenicity of OSCC cells and tumor angiogenesis in vivo. Taken together, these data show that miR-320 regulates the function of vascular endothelial cells by targeting NRP1 and has the potential to be developed as an anti-angiogenic or anti-cancer drug.     

Overexpression of focal adhesion kinase in vascular endothelial cells promotes angiogenesis in transgenic mice

OBJECTIVE: Focal adhesion kinase is implicated in the regulation of cell adhesion, migration, survival, and cell-cycle progression. However, the functions of focal adhesion kinase in endothelial cell (EC) in vivo remain unclear. This study aims to examine the role of FAK in EC function and angiogenesis in vivo by transgenic mice approach. METHOD: We generated transgenic mice which overexpressed chicken FAK in vascular endothelial cell under the control of the Tie-2 promoter and enhancer. FAK transgene was detected by RT-PCR, immunoprecipitation, and Western blot. The effect of FAK overexpression on angiogenesis was determined using skin wound healing and ischemia skeleton muscle models. RESULTS: Expression of FAK transgene was detected in all vessel-rich tissues. Expression of FAK protein was verified by antibody specific for the exogenous chicken FAK in lung homogenates and isolated EC. In the wound-induced angiogenesis model, the number of vessels in the granulation tissue of healing wound was significantly increased in the transgenic mouse compared to that of wild-type control mice. Similarly, in the ischemia skeleton muscle model, the density of capillaries was significantly increased in the transgenic mouse. CONCLUSION: These results indicate that FAK may play an important role in the promotion of angiogenesis in vivo.     

胰岛素经VEGF-A/VEGFR2途径促进恒河猴视网膜血管内皮细胞的血管新生

用人胰岛素处理恒河猴视网膜血管内皮细胞系RF/6A,测定其增殖、迁移、管腔形成情况和血管内皮生长因子A(VEGF-A)及其受体(VEGFR)的表达与磷酸化.与空白对照组相比,胰岛素促进RF/6A细胞增殖、迁移和管腔形成(均P＜0.01)、促进VEGF-A mRNA的表达和蛋白的活性(均P＜0.05);促进VEGFR2 mRNA的表达和蛋白的磷酸化(均P＜0.01),而对VEGFR1 mRNA的表达影响无统计学意义(P＞0.05)