Prevention of Metastasis by Inhibition of the Urokinase Receptor

• Published in: Proceedings of the National Academy of Sciences - PNAS 1993-06, Vol.90 (11), p.5021-5025
• Main Authors: Crowley, Craig W., Cohen, Robert L., Lucas, Brian K., Liu, Guohui, Shuman, Marc A., Levinson, Arthur D.
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - pathology; Amino Acid Sequence; Animals; Biological and medical sciences; Brain - enzymology; Brain - pathology; Brain Neoplasms - enzymology; Brain Neoplasms - pathology; Brain Neoplasms - secondary; Cell Line; Cell lines; Cells; Cellular biology; Chloramphenicol O-Acetyltransferase - genetics; Chloramphenicol O-Acetyltransferase - metabolism; CHO cells; Dissemination; Enzymes; Humans; Immunoglobulin G - biosynthesis; Immunoglobulin G - genetics; Lung - enzymology; Lung - pathology; Lung Neoplasms - enzymology; Lung Neoplasms - pathology; Lung Neoplasms - secondary; Lungs; Lymph nodes; Lymph Nodes - enzymology; Lymph Nodes - pathology; Lymphatic Metastasis; Male; Medical research; Medical sciences; Metastasis; Mice; Mice, Nude; Mutagenesis, Site-Directed; Neoplasm Invasiveness; Neoplasm Metastasis; Neoplasm Transplantation; Prostatic Neoplasms - pathology; Receptors; Receptors, Cell Surface - antagonists & inhibitors; Receptors, Urokinase Plasminogen Activator; Recombinant Fusion Proteins - biosynthesis; Recombinant Fusion Proteins - metabolism; Transfection; Transplantation, Heterologous; Tumor cell; Tumor cell line; Tumor Cells, Cultured; Tumors; Urokinase-Type Plasminogen Activator - biosynthesis; Urokinase-Type Plasminogen Activator - genetics; Urokinase-Type Plasminogen Activator - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.90.11.5021

The plasminogen activator urokinase (u-PA) mediates proteolysis by a variety of human tumor cells. Competitive displacement of u-PA from cellular binding sites results in decreased proteolysis in vitro, suggesting that the cell surface is the preferred site for u-PA-mediated protein degradation. We studied the effect of u-PA receptor blockade on the metastatic capacity of human PC3 prostate carcinoma cells, using transfectants which expressed chloramphenicol acetyltransferase (CAT). Eight weeks after subcutaneous inoculation of these cells into nude mice, CAT activity was detected in regional lymph nodes, femurs, lungs, and brain, thereby mimicking the organ tropism observed for naturally occurring metastases of prostate cancer. In a second transfection, CAT-expressing PC3 cells received cDNA encoding a mutant u-PA (Ser356→ Ala) which lacks enzymatic activity but which retains full receptor binding affinity. Three mutant u-PA expressors, each with 300 in regional lymph nodes, 40-100 in brain tissue, and 10-20 in lung tissue. Metastatic capacity was inhibited similarly when animals were given intermittent intraperitoneal injections of a u-PA/IgG fusion protein capable of displacing u-PA activity from the tumor cell surface. Our results indicate that cell surface u-PA activity is essential to the metastatic process. In addition, the assay system employed in these experiments may be generally useful in testing other therapeutic modalities to limit the spread of primary tumors.