Weng Wen-Tsan, Huang Shih-Chung, Ma Yi-Ling, Chan Hoi-Hung, Lin Shih-Wei, Wu Jian-Ching, Wu Chang-Yi, Wen Zhi-Hong, Wang E-Ming, Wu Chao-Liang, Tai Ming-Hong
Institute of Basic Medical Sciences, National Cheng Kung University, Tainan 701, Taiwan.
Department of Internal Medicine, Kaohsiung Armed Forces General Hospital, Kaohsiung 802, Taiwan; Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan.
Biochim Biophys Acta. 2014 Jun;1840(6):1850-60. doi: 10.1016/j.bbagen.2014.02.005. Epub 2014 Feb 14.
Gene therapy of proopiomelanocortin, the precursor of α-melanocyte-stimulating hormone (α-MSH), suppresses the neovascularization in tumors. However, the roles of α-MSH in angiogenesis remain unclear.
The influence of α-MSH on angiogenesis was evaluated by ex vivo rat aorta and in vivo, including transgenic zebrafish and chicken chorioallantoic membrane (CAM) assays. The effect of α-MSH on proliferation, matrix metalloproteinase (MMP) secretion, migration and tube formation was examined using human umbilical vein endothelial cells (HUVECs). The expression of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) was investigated by quantitative RT-PCR, immunoblot and immunofluorescent analysis. Antibodies' neutralization was employed to dissect the receptor(s) transmitting α-MSH signaling.
Application of α-MSH potently suppressed the microvessels sprouting in organotypic aortic rings. Besides, α-MSH perturbed the vessels development in zebrafish and chicken embryos. α-MSH (0.01-10nM) inhibited the MMP-2 secretion, migration and tube formation of HUVECs without affecting proliferation. Mechanistic studies unveiled α-MSH decreased the VEGF expression and release in HUVECs. Besides, α-MSH downregulated the VEGFR2 expression at transcriptional and translational levels. Importantly, α-MSH attenuated the Akt phosphorylation, but enhanced the expression of PTEN, endogenous antagonist of PI3K/Akt signaling. Expression analysis and antibody neutralization revealed that MC1-R and MC2-R participated in α-MSH-induced blockage of migration and VEGF/VEGFR2/Akt signaling. However, VEGF supply failed to reverse the anti-angiogenic function of α-MSH.
α-MSH inhibits the physiological angiogenesis by attenuating VEGF/VEGFR2/Akt signaling in endothelial cells.
α-MSH is a potent angiogenesis inhibitor targeting at endothelial VEGF/VEGFR2 signaling, which may have potential for therapeutic application.
阿片促黑激素皮质素原（α-黑素细胞刺激素（α-MSH）的前体）的基因疗法可抑制肿瘤中的新血管形成。然而，α-MSH在血管生成中的作用仍不清楚。
通过离体大鼠主动脉以及体内实验，包括转基因斑马鱼和鸡胚绒毛尿囊膜（CAM）实验，评估α-MSH对血管生成的影响。使用人脐静脉内皮细胞（HUVECs）检测α-MSH对增殖、基质金属蛋白酶（MMP）分泌、迁移和管腔形成的影响。通过定量RT-PCR、免疫印迹和免疫荧光分析研究血管内皮生长因子（VEGF）和VEGF受体2（VEGFR2）的表达。采用抗体中和法来剖析传递α-MSH信号的受体。
应用α-MSH可有效抑制器官型主动脉环中的微血管发芽。此外，α-MSH扰乱了斑马鱼和鸡胚中的血管发育。α-MSH（0.01 - 10nM）抑制HUVECs的MMP-2分泌、迁移和管腔形成，但不影响增殖。机制研究表明，α-MSH降低了HUVECs中VEGF的表达和释放。此外，α-MSH在转录和翻译水平下调VEGFR2的表达。重要的是，α-MSH减弱了Akt磷酸化，但增强了PI3K/Akt信号通路的内源性拮抗剂PTEN的表达。表达分析和抗体中和表明，MC1-R和MC2-R参与了α-MSH诱导的迁移阻断以及VEGF/VEGFR2/Akt信号通路。然而，VEGF的供应未能逆转α-MSH的抗血管生成功能。
α-MSH通过减弱内皮细胞中的VEGF/VEGFR2/Akt信号通路来抑制生理性血管生成。
α-MSH是一种针对内皮VEGF/VEGFR2信号的有效血管生成抑制剂，可能具有治疗应用潜力。
