Insulin-like growth factor binding protein-3 (IGFBP-3) is a 264-amino acid peptide (MW 29 kD) produced by the liver as well as other tissues. 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-I, the major mediator of the anabolic- and growth-promoting effects of growth hormone (GH).1 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.2,3
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-I levels are observed in GH deficiency or GH resistance,4 also epidemiologic studies suggest that low IGFBP-3 is associated with greater risk of aggressive, metastatic prostate cancers.5 The elevated serum IGFBP-3 and IGF-I levels indicate a sustained overproduction of GH, or excessive rhGH therapy. Both conditions are associated with generalized organomegaly,6 hypertension,7 diabetes,8 cardiomyopathy,9 osteoarthritis,10 and diminished longevity.
The Ansh Labs Intact IGFBP-3 Assay uses an acidification and neutralization method to dissociate Intact IGFBP-3 from all the binding subunits. Intact IGFBP-3 levels are quantified in the extracted samples using a highly sensitive and specific Intact IGFBP-3 ELISA. Total IGFBP-3 levels can be measured using Total IGFBP-3 ELISA (AL-120).
The concentration of bioactive IGF-I, total IGFBP-3 and intact IGFBP-3 in biological fluid can be measured accurately using immunoassay methods (Bioactive IGF-1 ELISA; AL-122, IGF-I inhibition mAb capture and IGF-1 C-terminal mAb) detection; Total IGFBP-3 ELISA; AL-120, C-terminal IGFBP-3 capture and detection mAb; and Intact IGFBP-3 ELISA; AL-149, C-terminal mAb capture and N-terminal mAb detection, respectively). The ratio of total to Intact IGFBP-3 concentration measured in individual subject over time will help normalizes the IGFBP-3 variability between subjects. The immunoassay methods designed for the measurement of bioactive IGF-I, total and Intact IGFBP-3 in patient samples could be of practical value for the diagnosis or prediction of various pathologies including growth abnormalities and cancer.
References:
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2. Baxter RC, Martin J : Radioimmunassay of growth hormone-dependent insulin-like growth factor binding protein in human plasma. J Clin Invest 1986, 78:1504-1512
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4. Wetterau L, Cohen P: Role of insulin-like growth factor monitoring in optimizing growth hormone therapy. J Ped Endocrinol Metab 2000;13:1371-1376
5. Cancer Res August 1, 2011 71;5154 IGFBP-3 Is a Metastasis Suppression Gene in Prostate Cancer
6. 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.
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8. 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.
9. 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.
10. 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.
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