title: Cyr61 is a target for heparin in reducing MV3 melanoma cell adhesion and migration via the integrin VLA-4.
abstract: The integrin VLA-4 is important for the metastatic dissemination of melanoma cells. We could recently show that heparin can block VLA-4 binding, which contributes, next to blocking P- and L-selectin, to the understanding of antimetastatic activities of heparin. The matricellular ligand Cyr61, secreted by numerous tumours, is responsible for increased tumourigenicity and metastasis. This has been attributed to Cyr61 binding to, and thus activating integrins. However, a VLA-4/Cyr61 axis has not yet been reported. Since Cyr61 possesses heparin binding capabilities, Cyr61 can be supposed as potential target for heparin to indirectly interfere with integrin functions. The present in vitro studies address (i) the existence of a Cyr61/VLA-4 axis and (ii) the functional relevance of heparin interference via Cyr61. The C-terminal module III of Cyr61 could be exposed as nanomolar affine binding site for VLA-4. A shRNA-based knockdown of Cyr61 in MV3 human melanoma cells reduced VLA-4-mediated cell binding to VCAM-1, migration on fibronectin, and integrin signalling functions significantly. Using a biosensor approach we provide insight into heparin interference with this process. The low-molecular-weight heparin tinzaparin, but not the pentasaccharide fondaparinux, binds module IV of Cyr61 with micromolar affinity. But tinzaparin cannot interfere with Cyr61 accumulation onto syndecan-4, indicating different Cyr61 binding sites for heparin and other GAGs. Nonetheless, tinzaparin affects the VLA-4 binding and signalling functions selectively via Cyr61 already at very low concentration most likely by blocking the cellular secreted free Cyr61. This study emphasises Cyr61 as promising, and hitherto not considered target for heparin to selectively influence integrin functions.
authors.affiliation: Prof. Dr. Gerd Bendas, Department of Pharmacy, Rheinische Friedrich Wilhelms University Bonn, An der Immenburg 4, 53121 Bonn, Germany, Tel.: +49 228 735250, Fax: +49 228 734692, E-mail: gbendas@uni-bonn.de.
authors.forename: P
authors.initials: P
authors.lastname: Schmitz
authors.forename: U
authors.initials: U
authors.lastname: Gerber
authors.forename: N
authors.initials: N
authors.lastname: Schütze
authors.forename: E
authors.initials: E
authors.lastname: Jüngel
authors.forename: R
authors.initials: R
authors.lastname: Blaheta
authors.forename: A
authors.initials: A
authors.lastname: Naggi
authors.forename: G
authors.initials: G
authors.lastname: Torri
authors.forename: G
authors.initials: G
authors.lastname: Bendas
mesh_terms: D000925:Anticoagulants / Q000378:metabolism; D063646:Carcinogenesis; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002465:Cell Movement; D055515:Cysteine-Rich Protein 61 / Q000235:genetics / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D000077425:Fondaparinux; D006493:Heparin / Q000031:analogs & derivatives / Q000378:metabolism*; D006495:Heparin, Low-Molecular-Weight / Q000378:metabolism*; D006801:Humans; D039041:Integrin alpha4beta1 / Q000378:metabolism*; D008545:Melanoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D058990:Molecular Targeted Therapy; D009362:Neoplasm Metastasis; D011134:Polysaccharides / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D053671:Syndecan-4 / Q000378:metabolism*; D000078222:Tinzaparin
chemical_list: D000925:Anticoagulants; D055515:Cysteine-Rich Protein 61; D006495:Heparin, Low-Molecular-Weight; D039041:Integrin alpha4beta1; D011134:Polysaccharides; D034741:RNA, Small Interfering; D053671:Syndecan-4; D000078222:Tinzaparin; D006493:Heparin; D000077425:Fondaparinux
keywords: Cyr61/CCN-1; VLA-4; heparin; melanoma cell adhesion; migration