Protein S, an antithrombotic factor, is synthesized and released by neural tumor cells.
Protein S, an anticoagulant factor in the protein C antithrombotic pathway, was found to be synthesized and released by six tumor cell lines of neural origin by western blotting and ELISA. The rate of synthesis ranged from three- to 11-fold higher than that of a microvascular endothelial cell line and 36-144% that of a hepatoma cell line. The secreted protein S displayed specific anticoagulant activity similar to that of purified plasma protein S, implying that it was fully gamma-carboxylated. Ten primary brain tumor tissues also expressed protein S antigen, as shown by western blot analysis. Expression of anticoagulantly active protein S by neural cells raises important questions concerning possible physiologic roles for this multidomain protein beyond its function in control of thrombosis.
Phillips
D J
DJ
Hematologic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia 30333.
Greengard
J S
JS
Fernandez
J A
JA
Ribeiro
M
M
Evatt
B L
BL
Griffin
J H
JH
Hooper
W C
WC
D015153:Blotting, Western; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005343:Fibrinolytic Agents / Q000378:metabolism*; D017293:Protein S / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000378:metabolism
D005343:Fibrinolytic Agents; D017293:Protein S