Role of urokinase plasminogen activator receptor in thrombospondin 1- mediated tumor cell invasion

Daniel Albo, David H. Berger, Vicki L. Rothman, George P. Tuszynski

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


We previously showed that thrombospondin 1 (TSP-1) upregulates the plasminogen/plasmin system and promotes breast tumor cell invasion. Preliminary data from our laboratory using neutralizing antibodies suggested that the upregulation in breast tumor cell invasion seen in response to TSP-1 involved the urokinase plasminogen activator receptor (uPAR). To confirm these findings in MDA-MB-231 breast cancer cells, we developed three other strategies to study the role of uPAR in tumor cell adhesion and TSP-1- mediated tumor cell invasion: (a) enzymatic cleavage of uPAR with glycosylphosphatidylinositol-specific phospholipase C; (b) inhibition at the mRNA level with a uPAR antisense construct (cells named LKAS-MDA); (c) inhibition of plasminogen binding with the lysine analogue ε-aminocaproic acid. Adhesion to laminin and type I and type IV collagen with and without the addition of ε-aminocaproic acid was studied. Tumor cell invasion was studied in a modified Boyden chamber collagen invasion assay. Antisense uPAR inhibition decreased uPAR expression by 48-66% and cell-associated urokinase plasminogen activator (uPA) by 30-68%. Additionally, antisense uPAR inhibition induced a 68-70% reduction in uPA and plasmin activities. Antisense uPAR transfection increased tumor cell adhesion by 46-53%. A similar effect was observed in ε-aminocaproic acid-treated MDA-MB-231 cells. TSP-1-mediated tumor cell invasion was almost completely inhibited by either antisense uPAR inhibition or treatment with phospholipase C or ε- aminocaproic acid. We conclude that uPAR plays a crucial role in the regulation of tumor cell adhesion and TSP-1-mediated tumor cell invasion.

Original languageEnglish (US)
Pages (from-to)331-338
Number of pages8
JournalJournal of Surgical Research
Issue number2
StatePublished - Apr 1999
Externally publishedYes


  • Thrombospondin 1 (TSP-1)
  • Urokinase plasminogen activator (uPA)
  • Urokinase plasminogen activator receptor (uPAR)

ASJC Scopus subject areas

  • Surgery


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