IGFBP-1, an insulin like growth factor binding protein, is a cell growth inhibitor.
A novel cell growth inhibitor, IDF45 (inhibitory diffusible factor), was recently purified to apparent homogeneity. It is a bifunctional molecule: able to bind Insulin like growth factor (IGF) and to 100% inhibit DNA synthesis stimulated by serum in fibroblasts. It was of interest to verify whether other members of the IGF-binding protein (IGFBP) family show the same bifunctional growth inhibitory properties. In this paper we show that purified IGFBP-1 derived from amniotic fluid is a cell growth inhibitor. In chick embryo fibroblasts, it inhibited DNA synthesis stimulated by serum. However the stimulation was maximally 60% inhibited and half of the inhibition was observed with 100ng/ml IGFBP-1. So the specific activity of IGFBP-1 is lower than that of IDF45. IGFBP-1 also reversibly prevented the CEF growth. In the same cells IGFBP-1 inhibited DNA synthesis stimulated by IGF-I. We demonstrated that the same protein IGFBP-1 is able to inhibit DNA synthesis stimulated by serum and by IGF-I. The possibility that IGFBP-1 is a bifunctional molecule is discussed.
Liu
L
L
Institute de Recherches Scientifiques sur le Cancer, Villejuif-France.
Brinkman
A
A
Blat
C
C
Harel
L
L
D000653:Amniotic Fluid / Q000737:chemistry; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D003470:Culture Media; D004261:DNA Replication / Q000187:drug effects*; D005260:Female; D006131:Growth Inhibitors / Q000494:pharmacology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D011247:Pregnancy; D011956:Receptors, Cell Surface / Q000302:isolation & purification / Q000494:pharmacology*; D017451:Receptors, Somatomedin
D003470:Culture Media; D006131:Growth Inhibitors; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D007334:Insulin-Like Growth Factor I