Overexpression of urokinase receptor in breast cancer cells results in increased tumor invasion, growth and metastasis

We have examined the role of urokinase receptor (uPAR) in tumor invasion and metastasis by developing a homologous model of uPAR overexpression in a rat breast cancer cell line (Mat B III) using gene transfer technique. Control (pRc‐CMV) and experimental plasmid (pRc‐uPAR‐S) were transfected into Mat B III cells by using Lipofectin reagent. Levels of uPAR production were accessed by Northern blotting, immunofluorescence, receptor binding and ELISA. At least 3 experimental clones (pRc‐uPAR‐S), expressing 3‐ to 5‐fold higher levels of uPAR than control (pRc‐CMV), were selected for further analysis. Experimental cells overexpressing uPAR showed a 4‐ to 5‐fold higher invasive capacity compared with control cells in a Boyden chamber invasion assay. Both control and experimental cells (1 × 106 cells) were injected into the mammary fat pad of syngeneic female Fischer rats. Animals were sacrificed at timed intervals and evaluated for the development of tumor growth and metastasis. Animals receiving cells overexpressing uPAR had significantly larger tumor volume and weight throughout our study. Furthermore, due to increased uPAR expression, experimental animals developed large metastatic lesions in liver, spleen and lymph nodes. Our results therefore demonstrate the role of uPAR in tumor progression, due to its ability to localize uPA within the tumor cell milieu. © 1996 Wiley‐Liss, Inc.

[1]  U. Weidle,et al.  Localization of the disulfide bonds in the NH2-terminal domain of the cellular receptor for human urokinase-type plasminogen activator. A domain structure belonging to a novel superfamily of glycolipid-anchored membrane proteins. , 1993, The Journal of biological chemistry.

[2]  N. Brünner,et al.  The urokinase receptor. Protein structure and role in plasminogen activation and cancer invasion , 1994 .

[3]  A. Mazar,et al.  Prevention of prostate‐cancer metastasis in vivo by a novel synthetic inhibitor of urokinase‐type plasminogen activator (uPA) , 1995, International journal of cancer.

[4]  F. Blasi,et al.  Two alternatively spliced mouse urokinase receptor mRNAs with different histological localization in the gastrointestinal tract , 1991, The Journal of cell biology.

[5]  D. Boyd,et al.  Role of the urokinase receptor in facilitating extracellular matrix invasion by cultured colon cancer. , 1991, Cancer research.

[6]  L. Kirkeby,et al.  Localization of urokinase-type plasminogen activator in stromal cells in adenocarcinomas of the colon in humans. , 1991, The American journal of pathology.

[7]  D. Cines,et al.  Overexpression of urokinase receptor increases matrix invasion without altering cell migration in a human osteosarcoma cell line. , 1993, Cancer research.

[8]  N. Brünner,et al.  Receptor for urokinase is present in tumor-associated macrophages in ductal breast carcinoma. , 1993, Cancer research.

[9]  A. Mazar,et al.  An amino-terminal fragment of urokinase isolated from a prostate cancer cell line (PC-3) is mitogenic for osteoblast-like cells. , 1990, Biochemical and biophysical research communications.

[10]  J. Russo,et al.  The etiopathogenesis of breast cancer prevention. , 1995, Cancer letters.

[11]  A. Mazar,et al.  Decreased urokinase receptor expression by overexpression of the plasminogen activator in a colon cancer cell line. , 1992, The Biochemical journal.

[12]  F. Blasi,et al.  Cellular receptor for urokinase plasminogen activator. Carboxyl-terminal processing and membrane anchoring by glycosyl-phosphatidylinositol. , 1991, The Journal of biological chemistry.

[13]  S. Rabbani,et al.  Urokinase overproduction results in increased skeletal metastasis by prostate cancer cells in vivo. , 1994, Cancer research.

[14]  M. Duffy,et al.  Urokinase plasminogen activator and urokinase plasminogen activator receptor in breast cancer , 1995, International journal of cancer.

[15]  E. Appella,et al.  Cloning and expression of the receptor for human urokinase plasminogen activator, a central molecule in cell surface, plasmin dependent proteolysis. , 1990, The EMBO journal.

[16]  F. Jänicke,et al.  Clinical Relevance of the Urokinase-Type and Tissue-Type Plasminogen Activators and of Their Type 1 Inhibitor in Breast Cancer , 1991, Seminars in thrombosis and hemostasis.

[17]  S. Rabbani,et al.  Induction of urinary plasminogen activator by retinoic acid results in increased invasiveness of human prostate cancer cells PC‐3 , 1995, The Prostate.

[18]  L. Liotta,et al.  Extracellular matrix 6: Role of matrix metalloproteinases in tumor invasion and metastasis , 1993, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[19]  S. Rabbani,et al.  Isolation and characterization of multiple isoforms of the rat urokinase receptor in osteoblasts , 1994, FEBS letters.

[20]  A. Levinson,et al.  Prevention of metastasis by inhibition of the urokinase receptor. , 1993, Proceedings of the National Academy of Sciences of the United States of America.