Garg Jaspal, Feng Yu-Xi, Jansen Sepp R, Friedrich Julian, Lezoualc'h Frank, Schmidt Martina, Wieland Thomas
Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
5th Medical Clinic, University Hospital Mannheim, Heidelberg University, Mannheim, Germany.
Oncotarget. 2017 Jul 4;8(27):44732-44748. doi: 10.18632/oncotarget.17267.
Chronic stress has been associated with the progression of cancer and antagonists for β-adrenoceptors (βAR) are regarded as therapeutic option. As they are also used to treat hemangiomas as well as retinopathy of prematurity, a role of endothelial β2AR in angiogenesis can be envisioned. We therefore investigated the role of β2AR-induced cAMP formation by analyzing the role of the cAMP effector molecules exchange factor directly activated by cAMP 1 (Epac1) and protein kinase A (PKA) in endothelial cells (EC). Epac1-deficient mice showed a reduced amount of pre-retinal neovascularizations in the model of oxygen-induced retinopathy, which is predominantly driven by vascular endothelial growth factor (VEGF). siRNA-mediated knockdown of Epac1 in human umbilical vein EC (HUVEC) decreased angiogenic sprouting by lowering the expression of the endothelial VEGF-receptor-2 (VEGFR-2). Conversely, Epac1 activation by β2AR stimulation or the Epac-selective activator cAMP analog 8-p-CPT-2'-O-Me-cAMP (8-pCPT) increased VEGFR-2 levels and VEGF-dependent sprouting. Similar to Epac1 knockdown, depletion of the monomeric GTPase Rac1 decreased VEGFR-2 expression. As Epac1 stimulation induces Rac1 activation, Epac1 might regulate VEGFR-2 expression through Rac1. In addition, we found that PKA was also involved in the regulation of angiogenesis in EC since the adenylyl cyclase (AC) activator forskolin (Fsk), but not 8-pCPT, increased sprouting in Epac1-depleted HUVEC and this increase was sensitive to a selective synthetic peptide PKA inhibitor. In accordance, β2AR- and AC-activation, but not Epac1 stimulation increased VEGF secretion in HUVEC.Our data indicate that high levels of catecholamines, which occur during chronic stress, prime the endothelium for angiogenesis through a β2AR-mediated increase in endothelial VEGFR-2 expression and VEGF secretion.
慢性应激与癌症进展相关，β - 肾上腺素能受体（βAR）拮抗剂被视为一种治疗选择。由于它们也用于治疗血管瘤以及早产儿视网膜病变，因此可以设想内皮β2AR在血管生成中发挥作用。我们通过分析环磷酸腺苷（cAMP）效应分子——直接由cAMP 1激活的交换因子（Epac1）和蛋白激酶A（PKA）在内皮细胞（EC）中的作用，研究了β2AR诱导的cAMP形成的作用。在氧诱导性视网膜病变模型中，Epac1缺陷小鼠视网膜前新生血管的数量减少，该模型主要由血管内皮生长因子（VEGF）驱动。在人脐静脉内皮细胞（HUVEC）中，通过小干扰RNA（siRNA）介导敲低Epac1可降低血管生成芽生，这是通过降低内皮VEGF受体-2（VEGFR-2）的表达实现的。相反，通过β2AR刺激激活Epac1或使用Epac选择性激活剂cAMP类似物8 - p - CPT - 2'- O - Me - cAMP（8 - pCPT）可增加VEGFR-2水平和VEGF依赖性芽生。与敲低Epac1类似，单体GTP酶Rac1的缺失也会降低VEGFR-2表达。由于Epac1刺激可诱导Rac1激活，Epac1可能通过Rac1调节VEGFR-2表达。此外，我们发现PKA也参与了内皮细胞血管生成的调节，因为腺苷酸环化酶（AC）激活剂福斯可林（Fsk）而非8 - pCPT可增加敲低Epac1的HUVEC中的芽生，并且这种增加对选择性合成肽PKA抑制剂敏感。相应地，β2AR和AC激活而非Epac1刺激可增加HUVEC中VEGF的分泌。我们的数据表明，在慢性应激期间出现的高水平儿茶酚胺，通过β2AR介导的内皮VEGFR-2表达增加和VEGF分泌，使内皮细胞易于发生血管生成。
