title: The role of VLA-4 binding for experimental melanoma metastasis and its inhibition by heparin.
abstract: BACKGROUND
  Heparin is known to efficiently attenuate metastasis in various tumour models by different mechanisms including inhibition of tumour cell contacts with soluble and cellular components such as inhibition of heparanase or P- and L-selectin. We recently showed that heparin efficiently binds to VLA-4 integrin in melanoma cells in vitro. Here we describe VLA-4 integrin as a mediator of melanoma metastasis that is inhibited by the low molecular weight heparin (LMWH) Tinzaparin.
  
  
  METHODS
  sh-RNA-mediated knock-down of VLA-4 integrin in B16F10 murine melanoma cells (B16F10-VLA-4kd) was performed and cell binding characteristics were investigated in vitro. Experimental metastasis of B16F10-VLA-4kd and B16F10 cells and interference by Tinzaparin were analysed in mice.
  
  
  RESULTS
  VLA-4 knock-down of B16F10 cells resulted in loss of VCAM-1 binding, but preserved the capacity to bind platelets through P-selectin. The observed reduced metastasis of B16F10-VLA-4kd cells confirmed the role of VLA-4 in this process. However, loss of melanoma VLA-4 function hardly further affected reduction of metastasis in P-selectin deficient mice. Tinzaparin treatment of mice injected with B16F10 and B16F10-VLA-4kd cells significantly reduced metastasis suggesting its potential to block both P- and L-selectin and VLA-4 in vivo. The use of N-acetylated heparin, which has no VLA-4 binding activity but blocks P- and L-selectin was less efficient than Tinzaparin in mice injected with B16F10 cells and B16F10-VLA-4kd cells.
  
  
  CONCLUSIONS
  These findings provide evidence that heparin inhibits experimental melanoma metastasis primarily by blocking VLA-4 and P-selectin.
authors.affiliation: Department of Pharmacy, Rheinische Friedrich Wilhelms University Bonn, 53121 Bonn, Germany. Electronic address: mschlesi@gmx.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Schlesinger
authors.affiliation: Institute of Physiology & Zürich Center for Integrative Human Physiology, University of Zurich, CH-8057 Zurich, Switzerland.
authors.forename: Marko
authors.initials: M
authors.lastname: Roblek
authors.affiliation: Department of Pharmacy, Rheinische Friedrich Wilhelms University Bonn, 53121 Bonn, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Ortmann
authors.affiliation: "G. Ronzoni" Institute for Chemical and Biochemical Research, 20133 Milano, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Naggi
authors.affiliation: "G. Ronzoni" Institute for Chemical and Biochemical Research, 20133 Milano, Italy.
authors.forename: Giangiacomo
authors.initials: G
authors.lastname: Torri
authors.affiliation: Institute of Physiology & Zürich Center for Integrative Human Physiology, University of Zurich, CH-8057 Zurich, Switzerland.
authors.forename: Lubor
authors.initials: L
authors.lastname: Borsig
authors.affiliation: Department of Pharmacy, Rheinische Friedrich Wilhelms University Bonn, 53121 Bonn, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Bendas
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology*; D006801:Humans; D039041:Integrin alpha4beta1 / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D008546:Melanoma, Experimental / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009362:Neoplasm Metastasis; D000078222:Tinzaparin; D019010:Vascular Cell Adhesion Molecule-1 / Q000737:chemistry*
chemical_list: D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D039041:Integrin alpha4beta1; D019010:Vascular Cell Adhesion Molecule-1; D000078222:Tinzaparin
keywords: Cell adhesion; Heparin; Melanoma cell metastasis; Selectins; VLA-4