Adhesion of osteosarcoma cells to the 70-kDa core region of thrombospondin-1 is mediated by the alpha 4 beta 1 integrin

Biochem Biophys Res Commun. 2002 Apr 26;293(1):86-92. doi: 10.1016/S0006-291X(02)00180-8.


Thrombospondin-1 (TSP-1) is an extracellular glycoprotein that is involved in a variety of physiological processes such as tumor cell adhesion, invasion, and metastasis. It has been hypothesized that TSP-1 provides an adhesive matrix for osteosarcoma cells. Here we present data showing that TSP-1 can promote cell substrate adhesion to U2OS and SAOS cells through the alpha 4 beta 1 integrin. The dose-dependent adhesion to TSP-1 was inhibited by anti-integrin antibodies directed against the alpha 4 or beta 1 subunit, but not by control antibodies against other integrins. To localize the potential alpha 4 beta 1-binding site within the TSP-1 molecule, the protein was subjected to limited proteolysis with chymotrypsin in the absence of calcium. The stable 70-kDa core fragment produced under these conditions promoted alpha 4 beta 1-dependent osteosarcoma cell adhesion in a manner similar to that of the intact protein. Moreover adhesion experiments with neutralizing antibodies revealed that the adhesion was totally dependent on the alpha 4 beta 1 interaction. Further blocking experiments with potential inhibitory peptides revealed that the alpha 4 beta 1-mediated adhesion was not influenced by peptides containing the RGD sequence. Attachment to the 70-kDa fragment was strongly inhibited by the CS-1 peptide, which represents the most active recognition domain for alpha 4 beta 1 integrin in fibronectin. The present data provide evidence that TSP-1 contains an alpha 4 beta 1 integrin-binding site within the 70-kDa core region.

MeSH terms

  • Bone Neoplasms
  • Cell Adhesion / drug effects
  • Cell Adhesion / physiology*
  • Humans
  • Integrin alpha4beta1
  • Integrins / physiology*
  • Osteosarcoma
  • Peptide Fragments / pharmacology
  • Receptors, Lymphocyte Homing / physiology*
  • Thrombospondin 1 / pharmacology
  • Thrombospondin 1 / physiology*
  • Tumor Cells, Cultured


  • Integrin alpha4beta1
  • Integrins
  • Peptide Fragments
  • Receptors, Lymphocyte Homing
  • Thrombospondin 1