Endocrinology, Vol 135, 2318-2326, Copyright © 1994 by Endocrine Society

ARTICLES

Interactions between insulin-like growth factor-I (IGF-I) and the system of plasminogen activators and their inhibitors in the control of IGF-binding protein-3 production and proteolysis in human osteosarcoma cells

C Lalou, C Silve, R Rosato, B Segovia and M Binoux
Institut National de la Sante et de la Recherche Medicale, Unite de Recherches sur la Regulation de la Croissance (U-142), Hopital Saint Antonie, Paris, France.

Limited proteolysis in vivo of insulin-like growth factor-binding protein-3 (IGFBP-3) by as yet unidentified serine proteases plays a key role in controlling the bioavailability of IGFBP-3-associated insulin- like growth factors (IGFs). Both the IGF system and the system of plasminogen activators (PAs) and their inhibitors (PAIs) are involved in bone remodeling, and plasmin has been shown to provoke dissociation of IGFBP-IGF complexes in cultured MG-63 human osteoblasts. The aim of this work was to investigate interactions between IGF-I and the PA/PAI system and their influence on IGFBP-3 production and proteolysis in this cell model. At confluency, MG-63 cells maintained for 3 days in serum-free medium constitutively secreted IGFBP-2 and small amounts of IGFBP-3 and IGFBP-4. As shown by Western ligand and immunoblot analyses of the culture medium and Northern blot analysis of IGFBP-3 messenger RNA, production of these IGFBPs, and of IGFBP-3 in particular, was dose dependently stimulated by the addition of 12.5-100 ng/ml recombinant human (rh) IGF-I. Increasing concentrations of plasminogen (0.05-3.5 micrograms/ml) added during the final 12 h of culture reduced the amounts of IGFBP detectable by Western ligand blotting, especially IGFBP-3. This reduction reflected proteolysis, as shown by immunoblotting, which revealed 30-, 20-, and 16-kilodalton fragments of IGFBP-3. In the presence of 25 ng/ml IGF-I, which stimulated IGFBP-3 production, proteolysis was reduced by approximately half. Incubation of glycosylated [125I]rh-IGFBP-3 as substrate in cell-free conditioned medium gave the same results. Addition of 50 ng/ml rhIGF-I to conditioned medium (to promote IGFBP-3-rhIGF-I complex formation) failed to diminish plasmin-induced proteolysis of IGFBP-3. Urokinase PA activity in the conditioned medium decreased significantly when the cells were cultured with rhIGF-I, indicating a direct action of IGF-I on urokinase PA and/or PAI production. Our results support the notion of a regulation loop whereby IGF-I controls its own bioavailability via its action on both IGFBP-3 production and the PA/PAI system, which regulates IGFBP-3 proteolysis. The proteolytic cleavages of IGFBP-3 caused by plasmin were the same as those caused in vivo by serine protease acting on this IGFBP.

This article has been cited by other articles:

				A. Giustina, G. Mazziotti, and E. Canalis Growth Hormone, Insulin-Like Growth Factors, and the Skeleton Endocr. Rev., August 1, 2008; 29(5): 535 - 559. [Abstract] [Full Text] [PDF]

				D. R. Clemmons, M. Sleevi, and W. H. Busby Jr. Recombinant, Nonglycosylated Human Insulin-Like Growth Factor-Binding Protein-3 (IGFBP-3) Is Degraded Preferentially after Administration to Type II Diabetics, Resulting in Increased Endogenous Glycosylated IGFBP-3 J. Clin. Endocrinol. Metab., December 1, 2005; 90(12): 6561 - 6568. [Abstract] [Full Text] [PDF]

				F. Miceli, A. Tropea, F. Minici, M. Orlando, G. Lamanna, M. F. Gangale, B. Panetta, F. Tiberi, S. Vaccari, R. Canipari, et al. Effects of Insulin-Like Growth Factor I and II on Prostaglandin Synthesis and Plasminogen Activator Activity in Human Umbilical Vein Endothelial Cells J. Clin. Endocrinol. Metab., January 1, 2005; 90(1): 372 - 378. [Abstract] [Full Text] [PDF]

				Y. S. Chang, K. Gong, S. Sun, D. Liu, A. K. El-Naggar, F. R. Khuri, W. K. Hong, and H.-Y. Lee Clinical Significance of Insulin-like Growth Factor-binding Protein-3 Expression in Stage I Non-Small Cell Lung Cancer Clin. Cancer Res., December 1, 2002; 8(12): 3796 - 3802. [Abstract] [Full Text] [PDF]

				S. Fanayan, S. M. Firth, and R. C. Baxter Signaling through the Smad Pathway by Insulin-like Growth Factor-binding Protein-3 in Breast Cancer Cells. RELATIONSHIP TO TRANSFORMING GROWTH FACTOR-beta 1 SIGNALING J. Biol. Chem., February 22, 2002; 277(9): 7255 - 7261. [Abstract] [Full Text] [PDF]

				B. A. Booth, M. Boes, B. L. Dake, K. L. Knudtson, and R. S. Bar IGFBP-3 binding to endothelial cells inhibits plasmin and thrombin proteolysis Am J Physiol Endocrinol Metab, January 1, 2002; 282(1): E52 - E58. [Abstract] [Full Text] [PDF]

				C. Lassarre, F. Duron, and M. Binoux Use of the Ligand Immunofunctional Assay for Human Insulin-Like Growth Factor (IGF) Binding Protein-3 (IGFBP-3) to Analyze IGFBP-3 Proteolysis and IGF-I Bioavailability in Healthy Adults, GH-Deficient and Acromegalic Patients, and Diabetics J. Clin. Endocrinol. Metab., May 1, 2001; 86(5): 1942 - 1952. [Abstract] [Full Text]

				C. LASSARRE and M. BINOUX Measurement of Intact Insulin-Like Growth Factor-Binding Protein-3 in Human Plasma Using a Ligand Immunofunctional Assay J. Clin. Endocrinol. Metab., March 1, 2001; 86(3): 1260 - 1266. [Abstract] [Full Text]

				H. Yu and T. Rohan Role of the Insulin-Like Growth Factor Family in Cancer Development and Progression J Natl Cancer Inst, September 20, 2000; 92(18): 1472 - 1489. [Abstract] [Full Text] [PDF]

				P. G. Campbell, S. K. Durham, J. D. Hayes, A. Suwanichkul, and D. R. Powell Insulin-like Growth Factor-binding Protein-3 Binds Fibrinogen and Fibrin J. Biol. Chem., October 15, 1999; 274(42): 30215 - 30221. [Abstract] [Full Text] [PDF]

				V. C. Russo, G. Rekaris, N. L. Baker, L. A. Bach, and G. A. Werther Basic Fibroblast Growth Factor Induces Proteolysis of Secreted and Cell Membrane-Associated Insulin-Like Growth Factor Binding Protein-2 in Human Neuroblastoma Cells Endocrinology, July 1, 1999; 140(7): 3082 - 3090. [Abstract] [Full Text]

				B. A. Booth, M. Boes, B. L. Dake, and R. S. Bar Isolation and characterization of plasmin-generated bioactive fragments of IGFBP-3 Am J Physiol Endocrinol Metab, March 1, 1999; 276(3): E450 - E454. [Abstract] [Full Text] [PDF]

				J. T. Allen, C. A. Bloor, R. A. Knight, and M. A. Spiteri Expression of Insulin-like Growth Factor Binding Proteins in Bronchoalveolar Lavage Fluid of Patients with Pulmonary Sarcoidosis Am. J. Respir. Cell Mol. Biol., August 1, 1998; 19(2): 250 - 258. [Abstract] [Full Text]

				P. G. Campbell, S. K. Durham, A. Suwanichkul, J. D. Hayes, and D. R. Powell Plasminogen binds the heparin-binding domain of insulin-like growth factor-binding protein-3 Am J Physiol Endocrinol Metab, August 1, 1998; 275(2): E321 - E331. [Abstract] [Full Text] [PDF]

				C. Skjærbæk, A. Kaal, J. Møller, N. Vahl, J. Weeke, H. Ørskov, and A. Flyvbjerg No Effect of Growth Hormone on Serum Insulin-Like Growth Factor Binding Protein-3 Proteolysis J. Clin. Endocrinol. Metab., April 1, 1998; 83(4): 1206 - 1210. [Abstract] [Full Text]

				B. Kubler, S. Cowell, J. Zapf, and T. Braulke Proteolysis of Insulin-Like Growth Factor Binding Proteins by a Novel 50-Kilodalton Metalloproteinase in Human Pregnancy Serum Endocrinology, April 1, 1998; 139(4): 1556 - 1563. [Abstract] [Full Text] [PDF]

				P. Bang and P. J. Fielder Human Pregnancy Serum Contains at Least Two Distinct Proteolytic Activities with the Ability To Degrade Insulin-Like Growth Factor Binding Protein-3 Endocrinology, September 1, 1997; 138(9): 3912 - 3917. [Abstract] [Full Text] [PDF]

				S. Xu, P. Savage, J. L. Burton, J. Sansom, and J. M. P. Holly Proteolysis of Insulin-Like Growth Factor-Binding Protein-3 by Human Skin Keratinocytes in Culture in Comparison to that in Skin Interstitial Fluid: The Role and Regulation of Components of the Plasmin System J. Clin. Endocrinol. Metab., June 1, 1997; 82(6): 1863 - 1868. [Abstract] [Full Text] [PDF]

				H. Salahifar, R. C. Baxter, and J. L. Martin Insulin-like Growth Factor Binding Protein (IGFBP)-3 Protease Activity Secreted by MCF-7 Breast Cancer Cells: Inhibition by IGFs Does Not Require IGF-IGFBP Interaction Endocrinology, April 1, 1997; 138(4): 1683 - 1690. [Abstract] [Full Text] [PDF]

				M. Menouny, M. Binoux, and S. Babajko Role of Insulin-Like Growth Factor Binding Protein-2 and Its Limited Proteolysis in Neuroblastoma Cell Proliferation: Modulation by Transforming Growth Factor-{beta} and Retinoic Acid Endocrinology, February 1, 1997; 138(2): 683 - 690. [Abstract] [Full Text] [PDF]

				D. L. Andress and D. L. Andress Heparin Modulates the Binding of Insulin-like Growth Factor (IGF) Binding Protein-5 to a Membrane Protein in Osteoblastic Cells J. Biol. Chem., November 24, 1995; 270(47): 28289 - 28296. [Abstract] [Full Text] [PDF]