title: α-Melanocyte-stimulating hormone inhibits angiogenesis through attenuation of VEGF/VEGFR2 signaling pathway.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  α-MSH inhibits the physiological angiogenesis by attenuating VEGF/VEGFR2/Akt signaling in endothelial cells.
  
  
  CONCLUSIONS
  α-MSH is a potent angiogenesis inhibitor targeting at endothelial VEGF/VEGFR2 signaling, which may have potential for therapeutic application.
authors: Institute of Basic Medical Sciences, National Cheng Kung University, Tainan 701, Taiwan. Electronic address: bppig@yahoo.com.tw.
authors: Wen-Tsan
authors: WT
authors: Weng
authors: Department of Internal Medicine, Kaohsiung Armed Forces General Hospital, Kaohsiung 802, Taiwan; Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan. Electronic address: Sghung@hotmail.com.
authors: Shih-Chung
authors: SC
authors: Huang
authors: Division of Nephrology, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan; Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan. Electronic address: ylma@vghks.gov.tw.
authors: Yi-Ling
authors: YL
authors: Ma
authors: Division of Gastroenterology, Department of Internal Medicine, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan. Electronic address: hoihungchan@gmail.com.
authors: Hoi-Hung
authors: HH
authors: Chan
authors: Institute of Marine Biotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan. Electronic address: Shiwey@yahoo.com.tw.
authors: Shih-Wei
authors: SW
authors: Lin
authors: Institute of Marine Biotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan. Electronic address: djbluestyle338@hotmail.com.
authors: Jian-Ching
authors: JC
authors: Wu
authors: Division of Nephrology, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan. Electronic address: cywu@mail.nsysu.edu.tw.
authors: Chang-Yi
authors: CY
authors: Wu
authors: Institute of Marine Biotechnology and Resources, Asia-Pacific Ocean Research Center, National Sun Yat-Sen University, Kaohsiung 804, Taiwan. Electronic address: wzh@mail.nsysu.edu.tw.
authors: Zhi-Hong
authors: ZH
authors: Wen
authors: Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan. Electronic address: emwang@vghks.gov.tw.
authors: E-Ming
authors: EM
authors: Wang
authors: Institute of Basic Medical Sciences, National Cheng Kung University, Tainan 701, Taiwan; Department of Biochemistry and Molecular Biology, National Cheng Kung University Medical College, Tainan 701, Taiwan. Electronic address: wumolbio@mail.ncku.edu.tw.
authors: Chao-Liang
authors: CL
authors: Wu
authors: Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan; Institute of Marine Biotechnology, National Sun Yat-Sen University, Kaohsiung 804, Taiwan; Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan. Electronic address: minghongtai@gmail.com.
authors: Ming-Hong
authors: MH
authors: Tai
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D008297:Male; D018919:Neovascularization, Physiologic / Q000187:drug effects; D051059:PTEN Phosphohydrolase / Q000032:analysis; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044102:Receptor, Melanocortin, Type 1 / Q000502:physiology; D044103:Receptor, Melanocortin, Type 2 / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects*; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000502:physiology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors / Q000502:physiology*; D015027:Zebrafish; D000521:alpha-MSH / Q000494:pharmacology*
chemical_list: D020533:Angiogenesis Inhibitors; D044102:Receptor, Melanocortin, Type 1; D044103:Receptor, Melanocortin, Type 2; D042461:Vascular Endothelial Growth Factor A; D000521:alpha-MSH; D040301:Vascular Endothelial Growth Factor Receptor-2; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; C487216:Pten protein, rat
keywords: Angiogenesis; HUVEC; Proopiomelanocortin; VEGF; α-MSH