Modified heparins inhibit integrin α_IIbβ₃ mediated adhesion of melanoma cells to platelets in vitro and in vivo

Abstract

The adhesion of tumor cells with platelets is important in the process of tumor metastasis. A huge work has indicated that antiadhesion is an effective strategy for metastasis inhibition. In this article, we assess the role of platelet integrin a IIb b 3 in adhesion of melanoma cells to platelets and the effects of heparin and modified heparins on the adhesion in vitro and in vivo. We show that platelet integrin a IIb b 3 is involved in the interaction of human melanoma A375 cells with platelets, and the high affinity epitope resides on the a IIb subunit rather than b 3 subunit. Heparin sulfatelike proteoglycans on tumor cell surface are implicated in the adhesion of A375 cells to integrin a IIb b 3 . We also show that RO-heparin, CR-heparin, N-2,3-DS-heparin and 2,3-O-DS-heparin can significantly inhibit A375 cells binding to the CHO cells expressing integrin a IIb b 3 under static and flow conditions, and remarkably inhibit the adhesion of A375 cells to the immobilized platelet layers under flow conditions. We find that A375 cells and B16F10 cells are arrested in the pulmonary vessels and adhered to platelets, and the initial interaction of tumor cells with platelets in lung vessel and long-term establishment of metastatic foci can be inhibited by heparin as well as CR-heparin and N-2,3-DS-heparin. These data suggest that modified heparins can inhibit tumor cellplatelet interaction mediated by platelet integrin a IIb b 3 and modified heparins may be a potential substitute for heparin in inhibiting tumor metastasis. ' UICCKey words: metastasis; adhesion; platelet; Integrin a IIb b 3; ; modified heparin Hematogenous metastasis of tumor cells is a cascade of events in which tumor cells separate from a primary tumor, intravasate into the bloodstream, evade innate immune surveillance, adhere to vascular endothelial cells of distant organs, and extravasate into tissue to generate new colonies. 1,2 It is well accepted that within vasculature circulating the interactions of tumor cells with platelets enhance tumor dissemination. Platelets may limit the ability of NK cells to lyse tumor cells and shield tumor cells from high shear forces that could potentially damage the tumor cells. 3,4 Furthermore, platelets facilitate the adhesion of tumor cells to vascular endothelium and release a number of growth factors, such as platelet-derived growth factor (PDGF), angiogenic growth factor, vascular endothelial growth factor (VEGF) and angiopoietin-1, which are required for metastasis and angiogenesis.Several studies support the view that tumor cell-associated platelets facilitate tumor cell metastasis. It has been shown that the elimination of circulating platelets with anti-platelet antibody result in a significant diminution of metastasis in several transplantable murine tumor models. 5,6 In addition, inhibition of platelet activation can decrease the metastatic potential of circulating tumor cells. 7,8 It is well known that platelets specifically express a IIb b 3, which has been reported to be involved in the interactio...

Heparin plays a key regulatory role via a p53/FAK‐dependent signaling in melanoma cell adhesion and migration

“…In fact, previous studies, performed with radioactive or fluorescent heparin derivatives showed that these compounds were bound and internalized by SMC (20), human endothelial cells (21) and rat neurons (33). Other reports show that heparin binds to specific cell surface adhesion molecules, for example, integrins to modulate the adhesive capabilities of different cell lines (34,35). The present study clearly demonstrates that M5 melanoma cells uptake heparin which results in its cytoplasmic and nuclear localization.…”

“…Phosphorylation of this tyrosine initiates a cascade of signal transduction events that renders the molecule a fully active kinase, able to initiate the formation of mature focal kinase complexes and capable adhesion (25). Heparin is previously shown to interfere with the function of integrin adhesion receptors during the selectin or VCAM-1 dependent attachment of melanoma cells (26,27). We hypothesized that heparin may affect the adhesive/migratory functions of FAK (28), the other major component of the focal kinase complexes.…”

Chemically modified heparins inhibit fibrinogen-bridged indirect adhesion between tumor cells and platelets

“…2). Previously, we demonstrated that the preincubation of tumor cells with a β3 integrin-blocking antibody inhibited the indirect adhesion between tumor cells and platelets (19). In the present study, we investigated the contribution of β3 integrins, expressed in platelets, as well as β3 and β1 integrins, expressed in tumor cells.…”

“…However, the hemorrhagic dangers caused by the marked anticoagulant effect of heparin has limited its application as an anti-metastatic drug. Previously, we demonstrated that certain chemically modified heparins with low anticoagulant activity were capable of blocking the P-selectin and αⅡbβ3 integrin-mediated adhesion of platelets and tumor cells (17)(18)(19).…”

The Role of Adhesion Receptors in Melanoma Metastasis and Therapeutic Intervention Thereof

“…The Role of Adhesion Receptors in Melanoma Metastasis and Therapeutic Intervention Thereof 397 heparin has also an inhibitory capacity to this binding (Zhang et al, 2009). Thrombin, interacting with its receptor PAR-1 on melanoma cells (protease-activated receptors-1) has a strong impact for regulating this interaction.…”