The role of the urokinase receptor in extracellular matrix degradation by ht29 human colon carcinoma cells

Abstract

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.

Cellular Localization, Invasion, and Turnover Are Differently Influenced by Healthy and Tumor-Derived Extracellular Matrix

“…The ability of LoVo and SW480 cells, and the failure of HT29 cells to invade the tumor ECM likely reflect the different armamentarium of these epithelial cell lines, such as expression of integrins, MMPs, and proteases (i.e., the prometastatic protease uPA, 47 absent in HT29 48 cells but expressed by LoVo 49 and SW480 50 cells). On the other side, the ability of the healthy-derived ECM to constrain the spreading of cells with invasive ability highlighted the contribution of host factors versus the intrinsic capacity of neoplastic cells to invade the matrix.…”

Proteinase inhibitors reduce basement membrane degradation by human breast cancer cell lines

“…The importance of uPA/plasmin in the in vitro invasion of various non-breast cancer cell lines has been well described (Mignatti et al, 1986;Kobayashi et al, 1992;Reiter et al, 1993). Aprotinin, tranexamic acid and amiloride have all been reported to have antimetastatic effect in vivo, including use in the treatment of cancer patients (Kikuchi et al, 1986(Kikuchi et al, , 1987Kellen et al, 1988;Uetsuji et al, 1992).…”

“…Of the former class, urokinase-type plasminogen activator (uPA) has been shown to be required for the invasion of several malignant cell types in vitro (Mignatti et al, 1986; Kobayashi et al, 1992;Reiter et al, 1993). Type IV collagenases are expressed in breast cancer (Monteagudo et al, 1990;Davies et al, 1993a), and there is accumulating evidence that MMPs are important in the invasion and metastasis of malignant cells (Mignatti et al, 1986;Reich et al, 1988; Davies et al, 1993b).…”

The Plasminogen Activation System in Tumour Invasion and Metastasis

“…Also, in vasive properties of tumour cells can be reduced when they are pretreated with anti-catalytic antibodies against u-PA124,151. Matrix degradation of u-PA posi tive tumour cells is reduced when tumour cells are pre treated with anti u-PA antibodies 180. In addition to anti-catalytic antibodies, the catalytic domain of u-PA can be blocked with PAI-1 or PAI-2.…”