Insulin-like growth factor binding protein-3 (IGFBP-3) is a 264-amino acid peptide (MW 29 kD) produced by the liver. It is the most abundant of a group of IGFBPs that transport, and control bioavailability and half-life of insulin-like growth factors (IGF), in particular IGF-1, the major mediator of the anabolic- and growth-promoting effects of growth hormone (GH). The protein forms a ternary complex with insulin-like growth factor acid-labile subunit (IGFALS) and either insulin-like growth factor (IGF) I or II, thus prolonging the half-life of IGFs and altering their interaction with cell surface receptors. Most of the IGFBP-3 in plasma is present as the high molecular weight ternary complex, however, small amounts of free IGFBP-3 are also found.1,2
IGFBP-3 also exhibits intrinsic growth-regulating effects that are not yet fully understood, but have evoked interest with regards to a possible role of IGFBP-3 as a prognostic tumor marker. Low IGFBP-3 and IGF-1 levels are observed in GH deficiency or GH resistance,3 also epidemiologic studies suggest that low IGFBP-3 is associated with greater risk of aggressive, metastatic prostate cancers.4 The elevated serum IGFBP-3 and IGF-1 levels indicate a sustained overproduction of GH, or excessive rhGH therapy. Both conditions are associated with generalized organomegaly,5 hypertension,6 diabetes,7 cardiomyopathy,8 osteoarthritis, 9 and diminished longevity.
The Ansh Labs Total IGFBP-3 Assay uses an acidification and neutralization method to dissociate IGFBP-3 from all the binding subunits. Total IGFBP-3 levels are quantified in the extracted samples using a highly sensitive and specific total IGFBP-3 ELISA. Similarly Intact IGFBP-3 levels can be measured using Intact IGFBP-3 ELISA (AL-149).
References:
1. Baxter RC, Martin J (1986): Radioimmunassay of growth hormone-dependent insulin-like growth factor binding protein in human plasma. J Clin Invest 78:1504-1512
2. Blum WF, Ranke MB, Kietzmann K, Gauggel E, Zeissel HJ, Bierich JR (1990) A specific radioimmunoassay for the growth hormone (GH)-dependent somatomedin-binding protein: its use for diagnosis of GH deficiency. J Clin Endocrinol Metab 70:1292-1298
3. Wetterau L, Cohen P: Role of insulin-like growth factor monitoring in optimizing growth hormone therapy. J Ped Endocrinol Metab 2000;13:1371-1376
4. Cancer Res August 1, 2011 71;5154 IGFBP-3 Is a Metastasis Suppression Gene in Prostate Cancer
5. Parama C, Fluiters E, de la Fuente J, et al: Monitoring of treatment success in patients with acromegaly: the value of serum insulin-like growth factor binding protein-3 and serum leptin measurements in comparison to plasma insulin-like growth factor 1 determination. Metabolism 2001; 50: 1117-1121.
6. Watanabe T1, Itokawa M, Nakagawa Y, Iguchi T, Katagiri T. Increased levels of insulin-like growth factor binding protein-3 in hypertensive patients with carotid atherosclerosis. Am. J. Hypertens. 2003 Sep; 16 (9 Pt 1):754-60.
7. Kim MS, Lee DY. Serum insulin-like growth factor-binding protein-3 level correlated with glycemic control and lipid profiles in children and adolescents with type 1 diabetes. J Pediatr Endocrinol Metab. 2014 Sep 20;27(9-10):857-61. doi: 10.1515/jpem-2013-0358.
8. Granata R, Broglio F, Migliorino D, Cutrupi S, Baldanzi G, Sireno M, Fubini A, Grazian A, Ghigo E, Pucci A. Neonatal and adult human heart tissues from normal subjects and patients with ischemic, dilated or hypertrophic cardiomyopathy express insulin-like growth factor binding protein-3 (IGFBP-3). J Endocrinol Invest. 2000 Dec;23(11):724-6.
9. Lee HS, Woo SJ, Koh HW, Ka SO, Zhou L, Jang KY, Lim HS, Kim HO, Lee SI, Park BH. Regulation of apoptosis and inflammatory responses by insulin-like growth factor binding protein 3 in fibroblast-like synoviocytes and experimental animal models of rheumatoid arthritis. Arthritis Rheumatol. 2014 Apr;66(4):863-73. doi: 10.1002/art.38303.
10. HHS Publication, 5th ed., 2007. Biosafety in Microbiological and Biomedical Laboratories. Available http://www.cdc.gov/biosafety/publications/bmbl5/BMBL5
11. DHHS (NIOSH) Publication No. 78€“127, August 1976. Current Intelligence Bulletin 13 - Explosive Azide Hazard. Available http:// www.cdc.gov/niosh.
12. Kricka L. Interferences in immunoassays €“ still a threat. Clin Chem 2000; 46: 1037€“1038.
