Emodin inhibits vascular endothelial growth factor-A-induced angiogenesis by blocking receptor-2 (KDR/Flk-1) phosphorylation.
Emodin (1,3,8-trihydroxy-6-methylanthraquinone), an active component in the root and rhizome of Rheum palmatum, is a tyrosine kinase inhibitor with a number of biological activities, including antitumor effects. Here, we examine the effects of emodin on vascular endothelial growth factor (VEGF)-A-induced angiogenesis, both in vitro and in vivo. In vitro, emodin dose-dependently inhibits proliferation, migration into the denuded area, invasion through a layer of Matrigel and tube formation of human umbilical vein endothelial cells (HUVECs) stimulated with VEGF-A. Emodin also inhibits basic fibroblast growth factor-induced proliferation and migration of HUVECs and VEGF-A-induced tube formation of human dermal microvascular endothelial cells. Specifically, emodin induces the cell cycle arrest of HUVECs in the G0/G1 phase by suppressing cyclin D1 and E expression and retinoblastoma protein phosphorylation, and suppresses Matrigel invasion by inhibiting the basal secretion of matrix metalloproteinase-2 and VEGF-A-stimulated urokinase plasminogen activator receptor expression. Additionally, emodin effectively inhibits phosphorylation of VEGF-A receptor-2 (KDR/Flk-1) and downstream effector molecules, including focal adhesion kinase, extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, Akt and endothelial nitric oxide synthase. In vivo, emodin strongly suppresses neovessel formation in the chorioallantoic membrane of chick and VEGF-A-induced angiogenesis of the Matrigel plug in mice. Our data collectively demonstrate that emodin effectively inhibits VEGF-A-induced angiogenesis in vitro and in vivo. Moreover, inhibition of phosphorylation of KDR/Flk-1 and downstream effector molecules is a possible underlying mechanism of the anti-angiogenic activity of emodin. Based on these data, we propose that an interaction of emodin with KDR/Flk-1 may be involved in the inhibitory function of emodin toward VEGF-A-induced angiogenesis in vitro and responsible for its potent anti-angiogenic in vivo.
Kwak
Hee-Jin
HJ
Laboratory of Functional Genomics, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
Park
Myung-Jin
MJ
Park
Chang-Min
CM
Moon
Sang-Ik
SI
Yoo
Doo-Hyun
DH
Lee
Hyung-Chahn
HC
Lee
Seung-Hoon
SH
Kim
Mi-Suk
MS
Lee
Hyean-Woo
HW
Shin
Woon-Seob
WS
Park
In-Chul
IC
Rhee
Chang Hun
CH
Hong
Seok-Il
SI
D000818:Animals; D001672:Biocompatible Materials; D002453:Cell Cycle; D002465:Cell Movement; D049109:Cell Proliferation; D003094:Collagen; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004642:Emodin / Q000494:pharmacology*; D042783:Endothelial Cells; D006801:Humans; D007797:Laminin; D051379:Mice; D009361:Neoplasm Invasiveness / Q000503:physiopathology; D009389:Neovascularization, Pathologic / Q000503:physiopathology*; D010766:Phosphorylation; D011509:Proteoglycans; D014470:Umbilical Cord / Q000098:blood supply; D042461:Vascular Endothelial Growth Factor A / Q000187:drug effects / Q000502:physiology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
D001672:Biocompatible Materials; D004338:Drug Combinations; D007797:Laminin; D011509:Proteoglycans; D042461:Vascular Endothelial Growth Factor A; C059485:matrigel; D003094:Collagen; D040301:Vascular Endothelial Growth Factor Receptor-2; D004642:Emodin