Plasminogen activator inhibitor-1 promotes angiogenesis by stimulating endothelial cell migration toward fibronectin

• Published in: Cancer research (Chicago, Ill.) Ill.), 2001-07, Vol.61 (14), p.5587-5594
• Main Authors: ISOGAI, Chiho, LAUG, Walter E, SHIMADA, Hiroyuki, DECLERCK, Paul J, STINS, Monique F, DURDEN, Donald L, ERDREICH-EPSTEIN, Anat, DECLERCK, Yves A
• Format: Article
• Language: English
• Subjects: Apoptosis - drug effects; Biological and medical sciences; Cell Adhesion - drug effects; Cell Movement - drug effects; Cells, Cultured; Dissemination; Dose-Response Relationship, Drug; Endothelium, Vascular - chemistry; Endothelium, Vascular - cytology; Endothelium, Vascular - drug effects; Fibronectins - pharmacology; Humans; Immunohistochemistry; Integrins - physiology; Medical sciences; Neovascularization, Pathologic - metabolism; Neovascularization, Pathologic - pathology; Neovascularization, Physiologic - drug effects; Plasminogen Activator Inhibitor 1 - biosynthesis; Plasminogen Activator Inhibitor 1 - pharmacology; Plasminogen Activator Inhibitor 1 - physiology; Recombinant Proteins - pharmacology; Tumor cell; Tumors; Vitronectin - pharmacology
• ISSN: 0008-5472; 1538-7445

Increased expression of plasminogen activator inhibitor-1 (PAI-1) in cancer patients is associated with unfavorable outcome, and the reason for this paradox has been poorly understood. We have previously reported elevated levels of PAI-1 in primary tumors of advanced neuroblastomas (Y. Sugiura et al., Cancer Res., 59: 1327-1336, 1999). Here we demonstrate that PAI-1 is coexpressed with the angiogenesis marker alpha(v)beta3 integrin in blood vessels of primary neuroblastoma tumors, suggesting that PAI-1 plays a role in angiogenesis. Using human brain microvascular endothelial cells (HBMECs), we found that PAI-1 inhibits alpha(v)beta3 integrin-mediated cell adhesion to vitronectin but promotes alpha5beta1-mediated migration from vitronectin toward fibronectin. Inhibition of vitronectin adhesion by PAI-1 did not induce HBMEC apoptosis. PAI-1 also inhibited endothelial tube formation on Matrigel in the presence of vitronectin but had a stimulatory effect in the presence of fibronectin. This effect of PAI-1 on microvascular endothelial cells is primarily related to the ability of PAI-1 to bind to vitronectin via its NH2-terminal domain and to interfere with cell adhesion to vitronectin. We propose that PAI-1 acts as a positive switch for angiogenesis by promoting endothelial cell migration away from their vitronectin-containing perivascular space toward fibronectin-rich tumor tissue. These observations provide a novel explanation for the enhancing effect of PAI-1 in cancer progression.