The role of the urokinase receptor in extracellular matrix degradation by HT29 human colon carcinoma cells.
Urokinase (u-PA) and the urokinase receptor (u-PAR), are thought to play a critical role in the invasive and metastatic properties of cancer cells. The HT29 human colon-carcinoma cell line was selected to evaluate these aspects. HT29 cells express u-PA receptors (100,000 sites/cell, KD = 1.5 nM), but no PA activity and therefore are unable to generate plasmin in the presence of plasminogen. These cells have been transfected with a human u-PA cDNA to investigate whether secreted u-PA would enhance in vitro extracellular matrix degradation, and whether the binding of u-PA to the cell surface is determinant. Five clones were selected for stable expression of high PA activity. These clones were capable of marked plasminogen-dependent degradation of R22 smooth-muscle-cell-derived extracellular matrix, whereas the parental cell line contributed to an insignificant breakdown only. Aprotinin, polyclonal anti-u-PA IgG, recombinant PAI-2, and co-culture with human PAI-I-producing mouse L cells significantly inhibited this degradation. Furthermore, a peptide displacing u-PA from its receptor as well as 2 different polyclonal anti-u-PA receptor IgGs decreased the breakdown after 24 hr by as much as 70% and 81%, respectively. These results show that the binding of u-PA to its receptor plays an important role in in vitro matrix breakdown by HT29 u-PA transfectants.
Swiss Institute for Experimental Cancer Research (ISREC), Epalinges/Lausanne.
L S
LS
Reiter
E K
EK
Kruithof
J F
JF
Cajot
B
B
Sordat
D002277:Carcinoma / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000378:metabolism*; D004247:DNA / Q000235:genetics; D005109:Extracellular Matrix / Q000378:metabolism*; D005342:Fibrinolysis; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D015849:Plasminogen Inactivators / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D011956:Receptors, Cell Surface / Q000502:physiology*; D055293:Receptors, Urokinase Plasminogen Activator; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014568:Urokinase-Type Plasminogen Activator / Q000502:physiology*
C524898:PLAUR protein, human; D015849:Plasminogen Inactivators; C524899:Plaur protein, mouse; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D004247:DNA; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator