3‐O‐Acetyloleanolic acid inhibits angiopoietin‐1‐induced angiogenesis and lymphangiogenesis via suppression of angiopoietin‐1/Tie‐2 signaling

Tumor angiogenesis and lymphangiogenesis are important processes in tumor progression and metastasis. The inhibitory effects of 3‐O‐acetyloleanolic acid (3AOA), a pentacyclic triterpenoid compound isolated from Vigna sinensis K., on tumor‐induced angiogenesis and lymphangiogenesis in vitro and in vivo were studied. Angiopoietin‐1 is an important angiogenic and lymphangiogenic factor secreted from colon carcinoma CT‐26 cells under hypoxia conditions. 3AOA inhibited proliferation, migration, and tube formation of angiopoietin‐1‐treated human umbilical vein endothelial cells (HUVEC) and human lymphatic microvascular endothelial cells (HLMEC). 3AOA reduced angiogenesis and lymphangiogenesis in angiopoietin‐1‐stimulated Matrigel plugs. Also, 3AOA inhibited tumor growth and tumor‐induced angiogenesis and lymphangiogenesis in an angiopoietin‐1‐induced CT‐26 allograft colon carcinoma animal model. 3AOA inhibited activation of the angiopoietin‐1 receptor Tie‐2 and activation of the downstream signaling factors FAK, AKT, and ERK1/2 that are involved in the angiopoietin‐1/Tie‐2‐signaling pathway. Thus, 3AOA has an inhibitory effect on angiogenesis and lymphangiogenesis induced by angiopoietin‐1 both in vitro and in vivo, and the inhibitory effect of 3AOA is probably due to suppression of angiopoietin‐1/Tie‐2 signaling in HUVEC and HLMEC.     

Expression of angiopoietin‐like protein 4 at the fracture site: Regulation by hypoxia and osteoblastic differentiation

Vascular disruption that occurs as a consequence of bone fracture, leads to hypoxia at the site of damage. Hypoxia regulates the expression of a number of genes that can modulate energy conservation, cell survival, tissue regeneration and angiogenesis. In this study we investigated the expression of Angiopoietin‐like 4, an adipocytokine that has additional roles in angiogenesis, at the fracture site. We demonstrate that Angptl4 mRNA expression increased early during fracture healing (day 3) returning close to baseline at day14. In the callus, Angptl4 mRNA was visualized in areas of condensing mesenchymal cells, callus cartilage and was especially high in mineralizing osteoblasts located in areas of new bone formation. In vitro, Angptl4 mRNA expression in osteoblasts increased under hypoxic conditions and in cells treated with the hypoxia mimetic desferrioxamine. Angptl4 levels were strongly induced at day 14 in differentiating MC3T3‐E1 osteoblastic cells. Exogenous ANGPTL4 increased expression of Runx2, Spp1, vegfa, and Alp mRNA in differentiating osteoblasts. We suggest that the distribution of Angptl4 in the callus may be driven by hypoxia and that Angptl4 may play a role in osteoblastic differentiation, and possibly angiogenesis via regulation of VEGF. Further studies could reveal a dual role for Angptl4 in angiogenesis and osteogenesis. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1364–1373, 2015.     

The angiopoietin pathway is modulated by PAR-1 activation on human endothelial progenitor cells

OBJECTIVES: The importance of protease-activated receptor-1 (PAR-1) in blood vessel development has been shown in knock-out mice. As endothelial progenitor cells (EPCs) express functional PAR-1, we examined whether PAR-1 stimulation by the peptide SFLLRN interfered with the angiopoietin pathway, that is EPC commitment, proliferation and migration. METHODS AND RESULTS: Given the strong PAR-1 expression on CD34+ cells, we tested the effect of SFLLRN 75 micromol L(-1) on the emergence of EPCs from cord blood. PAR-1 activation did not modify the number of colonies or the day of emergence, in keeping with the lack of induction of angiopoietin 1 gene expression. Conversely, SFLLRN treatment of EPCs induced angiopoietin 2 gene expression and protein synthesis. Experiments with polyclonal blocking antibodies showed that angiopoietin 2 was involved in the proliferative effect of PAR-1 activation. PAR-1 activation also enhanced migration toward angiopoietin 1 in a Boyden chamber assay. CONCLUSIONS: Our study demonstrates that PAR-1-induced proliferation of EPCs involves angiopoietin 2. PAR-1 also enhances EPC migration toward angiopoietin 1. These findings might explain the role of thrombin in neovascularization via the angiopoietin pathway.     

心力衰竭患者血浆CTRP3、血管生成素样蛋白2、sST2的浓度及预后价值

目的探讨心力衰竭患者血浆补体C1q肿瘤坏死因子相关蛋白3(C1q tumor necrosis factor related proteins-3,CTRP3)、血管生成素样蛋白2(angiopoietin like protein 2,angptl2)、可溶性致癌抑制因子2(soluble suppression of tumorigenicity 2,sST2)的浓度及预后价值。方法选择2014年8月到2018年2月在北京市垂杨柳医院心内科收治的心力衰竭患者122例作为心力衰竭组,并分为收缩性心力衰竭组62例和舒张性心力衰竭组60例两个亚组;对照组为非心力衰竭人群122例。采用酶联免疫吸附法检测混杂血浆CTRP3、angptl2、sST2浓度,随访调查患者的预后并进行相关性分析与预测价值分析。结果心力衰竭组的左心室射血分数(left ventricular ejection fraction,LVEF)低于对照组,左心室舒张末期内径(left ventricular end diastolic dimension,LVEDD)及血尿素、肌酐浓度高于对照组,差异有统计学意义(P<0.05)。两组总胆固醇、低密度脂蛋白胆固醇浓度比较,差异无统计学意义(P>0.05)。两亚组心功能与生化指标比较,差异无统计学意义(P>0.05)。心力衰竭组的血浆angptl2、sST2浓度高于对照组,CTRP3浓度低于对照组,差异有统计学意义(P<0.05);两亚组CTRP3、angptl2、s ST2浓度比较,差异无统计学意义(P>0.05)。随访至今,心力衰竭组患者中预后不良16例,发生率为13.1%。Pearson相关分析结果显示CTRP3、angptl2、sST2、LVEF、LVEDD、尿素、肌酐都与心力衰竭患者预后显著相关(P<0.05)。Cox回归模型分析显示CTRP3、angptl2、sST2为影响心力衰竭患者预后的主要因素(P<0.05)。结论心力衰竭患者血清CTRP3、angptl2、sST2浓度呈现异常表达情况,具有预测预后不良的价值,是心力衰竭预后评估的生物学标志物。     

Silk fibroin scaffolds loaded with angiogenic genes in adenovirus vectors for tissue regeneration

Vascularization remains a critical challenge in dermal tissue regeneration. In this study, a vascular endothelial growth factor (VEGF165) and angiopoietin‐1 (Ang‐1) dual gene coexpression vector that encoded green fluorescent protein (GFP) was constructed from an arginine–glycine–aspartic acid‐modified adenovirus. Silk fibroin (SF) scaffolds loaded with adenovirus vectors were fabricated by freeze‐drying method. In vitro, the human endothelial‐derived cell line EA.hy926 was infected with adenovirus vectors and then expressed GFP, secreted VEGF165 and Ang‐1, and promoted cell proliferation effectively. The VEGF165 and Ang‐1 genes loaded in the SF scaffolds significantly promoted the formation of abundant microvascular networks in the chick embryo chorioallantoic membrane. In vivo, angiogenic genes loaded in the scaffolds promoted vascularization and collagen deposition in scaffolds, thus effectively accelerating dermal tissue regeneration in a dorsal full‐thickness skin defect wound model in Sprague–Dawley rats. In conclusion, SF scaffolds loaded with arginine–glycine–aspartic acid‐modified adenovirus vectors encoding VEGF165 and Ang‐1 could stimulate the formation of vascular networks through the effective expression of target genes in vascular endothelial cells, thereby accelerating the regeneration of dermal tissue.