J. Biol. Chem., Vol. 261, Issue 31, 14474-14481, Nov, 1986
Purification of an active plasminogen activator inhibitor immunologically related to the endothelial type plasminogen activator inhibitor from the conditioned media of a human melanoma cell line [published erratum appears in J Biol Chem 1988 Jan 25;263(3):1593]
OF Wagner, M Vetterlein and BR Binder
24 established melanoma cell cultures were screened for their secretion of
plasminogen activators and plasminogen activator inhibitors into the
culture medium by sodium dodecyl sulfate-polyacrylamide gel electrophoresis
followed by conventional and reverse fibrin autography. Among the cell
lines investigated, 22 cell lines predominantly secreting tissue type
plasminogen activator (t-PA) and four cell lines additionally secreting
urokinase were found. The conditioned media of two cell lines (KRFM and
MJZJ) were found to contain plasminogen activator inhibitor (PAI) activity
at a Mr position of approximately 50,000. The PAI of one of the two
melanoma cell (MJZJ)-conditioned media found to contain PAI activity was
purified to apparent homogeneity employing concanavalin A-Sepharose
chromatography, gel filtration on Sephadex G-150, chromatography on
Affi-Gel blue, and affinity chromatography on a Sepharose 4B immobilized
monoclonal anti-t- PA IgG column. The purified melanoma PAI was found to be
a single chain protein, acid stable, immunologically related to the
endothelial derived PAI. In contrast to endothelial PAI, melanoma PAI
presented itself in the conditioned media of the melanoma cells and in the
purified preparation to an appreciable extent in its active form.