Cell surface expression of nucleolin mediates the antiangiogenic and antitumor activities of kallistatin

Abstract

Kallistatin is a unique serine proteinase inhibitor and heparin-binding protein. A previous study conducted by our group indicated that kallistatin has antiangiogenic and antitumoral activities. In the present study, we report that kallistatin specifically binds to membrane surface-expressed nucleolin with high affinity. Antibody-mediated neutralization or siRNA-induced nucleolin knockdown results in loss of kallistatin suppression of endothelial cell proliferation and migration in vitro and tumor angiogenesis and growth in vivo. In addition, we show that kallistatin is internalized and transported into cell nuclei of endothelial cells via nucleolin. Within the nucleus, kallistatin inhibits the phosphorylation of nucleolin, which is a critical step required for cell proliferation. Thus, we demonstrate that nucleolin is a novel functional receptor of kallistatin that mediates its antiangiogenic and antitumor activities. These findings provide mechanistic insights into the inhibitory effects of kallistatin on endothelial cell growth, tumor cell proliferation, and tumor-related angiogenesis.

AS1411 Nucleolin-Specific Binding Aptamers Reduce Pathological Angiogenesis through Inhibition of Nucleolin Phosphorylation

“…In order to determine whether these findings were mediated through the down regulation of NCL phosphorylation, we evaluated the ratio of phopho-NCL/NCL. Our findings indicate that AS1411 significantly reduced phopho-NCL/NCL ratio protein levels [ 61 ]. However, the effect of AS1411 on protein kinases down regulation or protein phosphatases up regulation is still matter of further research.…”

“…AS1411 inhibited essential functions of HUVEC such as proliferation, migration and tube formation. HUVEC constitutively express cell surface NCL which serves as a receptor for kallistatin and the interaction of both cell surface NCL and kallistatin mediates the antiangiogenic effects of kallistatin [ 61 ]; similarly, AS1411 inhibited HUVEC proliferation. MyH9 a protein associated with cell surface NCL promotes angiogenesis favoring cell motility [ 62 ], whether AS1411 nucleolin-binding aptamers downregulate MyH9 expression in HUVEC cannot be ruled out.…”

Nucleolin Mediates LPS-induced Expression of Inflammatory Mediators and Activation of Signaling Pathways

“…A large number of studies have shown that nucleolin is expressed on the cell surface of a variety of cells, and it participates in bacterial and viral invasions of host cells, inflammatory immune response, angiogenesis, inhibition of tumor cell proliferation, and other physiological processes [15][16][17][18][19] . However, many investigators have demonstrated that LPS-induced inflammatory response can't be completely abolished by functional deficiency of CD14, TLR2, 4 and LBP.…”

Future Perspectives of Therapeutic, Diagnostic and Prognostic Aptamers in Eye Pathological Angiogenesis

“…In this context, our laboratory documented for the first time that NCL is able to translocate into the cell surface after angiogenic stimulus in an in vivo corneal neovascularization model [148]. Cell membrane NCL serves as a receptor for a diverse type of molecules, such as growth factors, laminin [149], P-Selectin [150], midkine [151], kallistatin [152], endostatin [153], pleiotrophin [154] and microorganisms such as HIV virus [155], Helicobacter pylori and Escherichia coli [156,157]. Surface NCL has been implicated in cell division, cell migration and adhesion, and participates in angiogenesis and tumor metastasis [142,[158][159][160][161][162][163][164].…”