title: Cyclopeptide RA-V inhibits angiogenesis by down-regulating ERK1/2 phosphorylation in HUVEC and HMEC-1 endothelial cells.
abstract: OBJECTIVE
  Anti-angiogenic agents have recently become one of the major adjuvants for cancer therapy. A cyclopeptide, RA-V, has been shown to have anti-tumour activities. Its in vitro anti-angiogenic activities were evaluated in the present study, and the underlying mechanisms were also assessed.
  
  
  METHODS
  Two endothelial cell lines, human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (HMEC-1), were used. The effects of RA-V on the proliferation, cell cycle phase distribution, migration, tube formation and adhesion were assessed. Western blots and real-time PCR were employed to examine the protein and mRNA expression of relevant molecules.
  
  
  RESULTS
  RA-V inhibited HUVEC and HMEC-1 proliferation dose-dependently with IC(50) values of 1.42 and 4.0 nM respectively. RA-V inhibited migration and tube formation of endothelial cells as well as adhesion to extracellular matrix proteins. RA-V treatment down-regulated the protein and mRNA expression of matrix metalloproteinase-2. Regarding intracellular signal transduction, RA-V interfered with the activation of ERK1/2 in both cell lines. Furthermore, RA-V significantly decreased the phosphorylation of JNK in HUVEC whereas, in HMEC-1, p38 MAPK was decreased.
  
  
  CONCLUSIONS
  RA-V exhibited anti-angiogenic activities in HUVEC and HMEC-1 cell lines with changes in function of these endothelial cells. The underlying mechanisms of action involved the ERK1/2 signalling pathway. However, RA-V may regulate different signalling pathways in different endothelial cells. These findings suggest that RA-V has the potential to be further developed as an anti-angiogenic agent.
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Grace G L
authors.initials: GG
authors.lastname: Yue
authors.forename: Jun-Ting
authors.initials: JT
authors.lastname: Fan
authors.forename: Julia K M
authors.initials: JK
authors.lastname: Lee
authors.forename: Guang-Zhi
authors.initials: GZ
authors.lastname: Zeng
authors.forename: Tina W F
authors.initials: TW
authors.lastname: Ho
authors.forename: Kwok-Pui
authors.initials: KP
authors.lastname: Fung
authors.forename: Ping-Chung
authors.initials: PC
authors.lastname: Leung
authors.forename: Ning-Hua
authors.initials: NH
authors.lastname: Tan
authors.forename: Clara B S
authors.initials: CB
authors.lastname: Lau
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D002468:Cell Physiological Phenomena / Q000187:drug effects; D015536:Down-Regulation; D042783:Endothelial Cells / Q000187:drug effects* / Q000502:physiology; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008516:Medicine, Chinese Traditional; D051379:Mice; D008810:Mice, Inbred C57BL; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010766:Phosphorylation
chemical_list: D020533:Angiogenesis Inhibitors; D010456:Peptides, Cyclic; C043547:RA V; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3