RGD-peptide presents anti-adhesive effect, but not direct pro-apoptotic effect on endothelial progenitor cells.
Circulating endothelial progenitor cells (EPCs) contribute to neovascularization in tumor or ischemic tissues by multi-step events, including adhesion, migration, chemoattraction, and differentiation to endothelial cells. Anti-angiogenic RGD-peptides have been shown to directly induce apoptosis in human umbilical vein endothelial cells (HUVECs) and T cells. Here, we examined the effects of RGD-peptides on EPCs in terms of adhesive differentiation and apoptosis. When mononuclear cells (MNCs) isolated from human cord blood were cultured on fibronectin-coated plates for 7 days, RGD-peptide treatment decreased dose-dependently the number of adherent cells double positive for DiI-ac-LDL uptake and UEA-1 binding. The cells treated with RGD peptide were also stained less strongly by vWF or KDR antibody by immunofluorescence staining. Immobilization of the RGD-peptide promoted cell adhesion, but resulted in a deficiency in the development of ability of ac-LDL uptake and UEA-1 binding, showing an antagonistic effect. Accordingly, ex vivo-cultivated EPCs expressed integrin alpha5, alphav, beta1, beta3, and beta5, and antibodies to integrins alpha5, alphav, and beta1 decreased the number of adherent cells. However, viability of total MNCs containing early EPCs was not affected by RGD-peptide. In addition, neither an increase in apoptotic cell death nor a direct activation of caspase-3 by RGD-peptide was detected in ex vivo-cultivated EPCs, unlike in HUVECs. Interestingly, RGD-peptide rather enhanced Bcl-2 expression in ex vivo-cultivated EPCs and the EPCs themselves with a high Bcl-2/Bax ratio are comparatively resistant to apoptosis. Therefore, these results suggest that RGD-peptides may inhibit EPC differentiation by anti-adhesive effect, but not by a direct pro-apoptotic effect.
Kim
Sun-Yong
SY
Cancer Research Institute, Department of Biomedical Sciences, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea.
Oh
Ho-Kyun
HK
Ha
Jung-Min
JM
Ahn
Hyun-Young
HY
Shin
Jong-Chul
JC
Baek
Sang Hong
SH
Lim
Sung Cil
SC
Joe
Young Ae
YA
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D009842:Oligopeptides / Q000008:administration & dosage*
D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid