Transformation of rat liver cell line by Rous sarcoma virus causes loss of cell surface fibronectin, accompanied with secretion of metallo-proteinase that preferentially digests the fibronectin.
An epithelial cell line derived from the liver of a normal Buffalo rat (BRL) was transformed by Rous sarcoma virus (RSV). The RSV-transformed cells were separated into five clones (RSV-BRL1 through 5), which were morphologically different. RSV-BRL cells exhibited the following characteristics distinct from those of BRL cells: tumorigenicity, irregular cell arrangement, loose intercellular junction, growth in soft agar (anchorage-independent growth) except for RSV-BRL3 and 5, and loss of cell surface fibronectin. When BRL cells were cultured in the standard medium supplemented with the serum-free conditioned medium of RSV-BRL cells, the amount of the cell surface fibronectin decreased significantly. It was found that RSV-BRL cells secreted a proteinase capable of hydrolyzing the fibronectin, whereas BRL cells secreted hardly any of this proteinase. The fibronectin-hydrolyzing proteinase (FNase) could also hydrolyze plasma fibronectin added as an exogenous substrate. The hydrolysis of plasma fibronectin was inhibited by ethylenediamine tetraacetate, but stimulated by rho-chloromercuribenzoate and calcium ion. This indicates that FNase is a metallo-enzyme, but not a serine or thiol enzyme. In addition to the proteinase, RSV-BRL cells secreted plasminogen activator and a proteinase inhibitor which inhibited the activity of plasmin but not FNase.
Miyazaki
K
K
Institute for Protein Research, Osaka University.
Ashida
Y
Y
Kihira
Y
Y
Mashima
K
K
Yamashita
J
J
Horio
T
T
D000818:Animals; D001358:Avian Sarcoma Viruses; D002460:Cell Line; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D003114:Colony-Forming Units Assay; D004591:Electrophoresis, Polyacrylamide Gel; D005340:Fibrinogen / Q000032:analysis; D005353:Fibronectins / Q000276:immunology / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D010960:Plasminogen Activators / Q000378:metabolism; D051381:Rats
D005353:Fibronectins; D005340:Fibrinogen; D010447:Peptide Hydrolases; D010960:Plasminogen Activators