1
|
Wang Y, Zhang H, Zhang X, Mu P, Zhao L, Qi R, Zhang Y, Zhu X, Dong Y. The role of IGFBP-3 in tumor development and progression: enlightenment for diagnosis and treatment. Med Oncol 2024; 41:141. [PMID: 38714554 DOI: 10.1007/s12032-024-02373-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 03/25/2024] [Indexed: 05/10/2024]
Abstract
IGFBP-3 is aberrantly expressed in many tumor types, and its serum and tumor tissue levels provide auxiliary information for assessing the degree of tumor malignancy and patient prognosis, making it a potential therapeutic target for human malignancies and conferring it remarkable clinical value for determining patient prognosis. In this review, we provide a comprehensive overview of the aberrant expression, diverse biological effects, and clinical implications of IGFBP-3 in tumors and its role as a potential prognostic marker and therapeutic target for tumors. In addition, we summarize the signaling pathways through which IGFBP-3 exerts its effects. IGFBP-3 comprises an N-terminal, an intermediate region, and a C-terminal structural domain, each exerting different biological effects in several tumor cell types in an IGF-dependent/non-independent manner. IGFBP-3 shares an intricate relationship with the tumor microenvironment, thereby affecting tumor growth. Overall, IGFBP-3 is an essential regulatory factor that mediates tumor occurrence and progression. Gaining deeper insights into the fundamental characteristics of IGFBP-3 and its role in various tumor types will provide new perspectives and allow for the development of novel strategies for cancer diagnosis, treatment, and prognostic evaluation.
Collapse
Affiliation(s)
- Yudi Wang
- Department of Immunology, Binzhou Medical University, Yantai, China
| | - He Zhang
- Department of Immunology, Qiqihar Medical University, Qiqihar, China
| | - Xuehua Zhang
- Department of Precision Biomedical Laboratory, Liaocheng People's Hospital, Liaocheng, China
| | - Peizheng Mu
- School of Computer and Control Engineering, Yantai University, Yantai, China
| | - Leilei Zhao
- Department of Immunology, Binzhou Medical University, Yantai, China
| | - Ruomei Qi
- Department of Immunology, Binzhou Medical University, Yantai, China
| | - Yurui Zhang
- Department of Immunology, Binzhou Medical University, Yantai, China
| | - Xiao Zhu
- School of Computer and Control Engineering, Yantai University, Yantai, China.
| | - Yucui Dong
- Department of Immunology, Binzhou Medical University, Yantai, China.
| |
Collapse
|
2
|
An Z, Chen X, Li J. Response to Different Oxygen Partial Pressures and Evolution Analysis of Apoptosis-Related Genes in Plateau Zokor ( Myospalax baileyi). Front Genet 2022; 13:865301. [PMID: 35754836 PMCID: PMC9214310 DOI: 10.3389/fgene.2022.865301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/28/2022] [Indexed: 11/30/2022] Open
Abstract
The plateau zokor (Myospalax baileyi) is a native species of the Qinghai–Tibet Plateau that spends its entire life underground in sealed burrows with hypoxic conditions. The present study aimed to assess the sequence characteristics of apoptosis-related genes and the response to different oxygen partial pressures (pO2) in plateau zokor and Sprague-Dawley rats. The sequences of the p53-induced protein with a death domain (Pidd), p53-upregulated modulator of apoptosis (Puma), insulin-like growth factor binding protein 3 (Igfbp3), and apoptosis protease-activating factor 1 (Apaf1) were evaluated concerning homology and convergent evolution sites, and their mRNA levels were evaluated in different tissues under 14.13 (3,300 m) and 16.12 kPa (2,260 m) pO2 conditions. Our results showed that, (1) the sequences of the apoptosis-related genes in plateau zokor were highly similar to those of Nannospalax galili, followed by Rattus norvegicus; (2). Pidd, Puma, Igfbp3, and Apaf1 of plateau zokor were found to have five, one, two, and five convergent sites in functional domains with N. galili, respectively. Lastly (3), under low pO2, the expression of Pidd and Puma was downregulated in the lung of plateau zokors. In turn, Igfbp3 and Apaf1 were upregulated in the liver and lung, and Puma was upregulated in the skeletal muscle of plateau zokor under low pO2. In Sprague-Dawley rats, low pO2 downregulated Puma and Apaf1 expression in the liver and downregulated Igfbp3 and Puma in the lung and skeletal muscle separately. In contrast, low pO2 upregulated Pidd expression in the liver and skeletal muscle of Sprague-Dawley rats. Overall, the expression patterns of Apaf1, Igfbp3, and Puma showed the opposite pattern in the liver, lung, and skeletal muscle, respectively, of plateau zokor as compared with Sprague-Dawley rats. In conclusion, for the long-time adaptation to hypoxic environments, Pidd, Puma, Igfbp3, and Apaf1 of plateau zokor underwent convergent evolution, which we believe may have led to upregulation of their levels under low oxygen partial pressures to induce apoptosis, so as to suppress tumorigenesis under hypoxic environments in plateau zokor.
Collapse
Affiliation(s)
- Zhifang An
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China
| | - Xiaoqi Chen
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China.,Department of Obstetrics and Gynaecology, Affiliated Hospital of Qinghai University, Xining, China.,Research Center for High Altitude Medicine, Qinghai University, Xining, China
| | - Jimei Li
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, China.,Research Center for High Altitude Medicine, Qinghai University, Xining, China.,Department of General Medicine, Qinghai Provincial People's Hospital, Xining, China
| |
Collapse
|
3
|
Cai Q, Dozmorov M, Oh Y. IGFBP-3/IGFBP-3 Receptor System as an Anti-Tumor and Anti-Metastatic Signaling in Cancer. Cells 2020; 9:cells9051261. [PMID: 32443727 PMCID: PMC7290346 DOI: 10.3390/cells9051261] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/15/2020] [Accepted: 05/18/2020] [Indexed: 12/11/2022] Open
Abstract
Insulin-like growth factor binding protein-3 (IGFBP-3) is a p53 tumor suppressor-regulated protein and a major carrier for IGFs in circulation. Among six high-affinity IGFBPs, which are IGFBP-1 through 6, IGFBP-3 is the most extensively investigated IGFBP species with respect to its IGF/IGF-I receptor (IGF-IR)-independent biological actions beyond its endocrine/paracrine/autocrine role in modulating IGF action in cancer. Disruption of IGFBP-3 at transcriptional and post-translational levels has been implicated in the pathophysiology of many different types of cancer including breast, prostate, and lung cancer. Over the past two decades, a wealth of evidence has revealed both tumor suppressing and tumor promoting effects of IGF/IGF-IR-independent actions of IGFBP-3 depending upon cell types, post-translational modifications, and assay methods. However, IGFBP-3′s anti-tumor function has been well accepted due to identification of functional IGFBP-3-interacting proteins, putative receptors, or crosstalk with other signaling cascades. This review mainly focuses on transmembrane protein 219 (TMEM219), which represents a novel IGFBP-3 receptor mediating antitumor effect of IGFBP-3. Furthermore, this review delineates the potential underlying mechanisms involved and the subsequent biological significance, emphasizing the clinical significance of the IGFBP-3/TMEM219 axis in assessing both the diagnosis and the prognosis of cancer as well as the therapeutic potential of TMEM219 agonists for cancer treatment.
Collapse
Affiliation(s)
- Qing Cai
- Department of Pathology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298, USA; (Q.C.); (M.D.)
| | - Mikhail Dozmorov
- Department of Pathology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298, USA; (Q.C.); (M.D.)
- Department of Biostatistics, Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Youngman Oh
- Department of Pathology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298, USA; (Q.C.); (M.D.)
- Correspondence: ; Tel.: +1-804-827-1324
| |
Collapse
|
4
|
Yücel ÇY, Erden G, Yılmaz FM, Sezer S, Çalcı E. IGF-I and IGFBP-3 levels and their correlations with carcinoembryonic antigen in colorectal cancer patients. ALEXANDRIA JOURNAL OF MEDICINE 2019. [DOI: 10.1016/j.ajme.2017.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
| | - Gönül Erden
- Ankara Numune Training and Research Hospital, Biochemistry Clinic, Turkey
| | - Fatma Meriç Yılmaz
- Yıldırım Beyazıt University, Medical Faculty, Department of Biochemistry, Turkey
| | - Sevilay Sezer
- Ankara Numune Training and Research Hospital, Biochemistry Clinic, Turkey
| | - Esin Çalcı
- Ankara Numune Training and Research Hospital, Biochemistry Clinic, Turkey
| |
Collapse
|
5
|
Kotzsch A, Skovgaard T, Buus U, Andersen S, Devkota K, Berthelsen J. A substrate-optimized electrophoretic mobility shift assay for ADAM12. Anal Biochem 2014; 452:34-42. [PMID: 24534253 DOI: 10.1016/j.ab.2014.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/31/2014] [Accepted: 02/02/2014] [Indexed: 11/17/2022]
Abstract
ADAM12 belongs to the A disintegrin and metalloprotease (ADAM) family of secreted sheddases activating extracellular growth factors such as epidermal growth factor receptor (EGFR) ligands and tumor necrosis factor-alpha (TNF-α). ADAM proteases, most notably ADAM17 (TNF-α-converting enzyme), have long been investigated as pharmaceutical drug targets; however, due to lack of potency and in vivo side effects, none of the small-molecule inhibitors discovered so far has made it beyond clinical testing. Ongoing research on novel selective inhibitors of ADAMs requires reliable biochemical assays to validate molecular probes from large-scale screening efforts. Here we describe an electrophoretic mobility shift assay for ADAM12 based on the identification of an optimized peptide substrate that is characterized by excellent performance and reproducibility.
Collapse
Affiliation(s)
- Alexander Kotzsch
- Facility for Protein Purification and Function at the Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark.
| | - Tine Skovgaard
- Facility for Protein Purification and Function at the Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Uwe Buus
- Facility for Protein Purification and Function at the Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Simon Andersen
- Facility for Protein Purification and Function at the Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Kanchan Devkota
- Facility for Protein Purification and Function at the Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Jens Berthelsen
- Facility for Protein Purification and Function at the Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| |
Collapse
|
6
|
Lee H, Kim SR, Oh Y, Cho SH, Schleimer RP, Lee YC. Targeting insulin-like growth factor-I and insulin-like growth factor-binding protein-3 signaling pathways. A novel therapeutic approach for asthma. Am J Respir Cell Mol Biol 2014; 50:667-77. [PMID: 24219511 PMCID: PMC5455301 DOI: 10.1165/rcmb.2013-0397tr] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/05/2013] [Indexed: 02/04/2023] Open
Abstract
Insulin-like growth factor (IGF)-I has been recognized to play critical roles in the pathogenesis of asthma, whereas IGF-binding protein (IGFBP)-3 blocks crucial physiologic manifestations of asthma. IGF-I enhances subepithelial fibrosis, airway inflammation, airway hyperresponsiveness, and airway smooth muscle hyperplasia by interacting with various inflammatory mediators and complex signaling pathways, such as intercellular adhesion molecule-1, and the hypoxia-inducible factor/vascular endothelial growth factor axis. On the other hand, IGFBP-3 decreases airway inflammation and airway hyperresponsiveness through IGFBP-3 receptor-mediated activation of caspases, which subsequently inhibits NF-κB signaling pathway. It also inhibits the IGF-I/hypoxia-inducible factor/vascular endothelial growth factor axis via IGF-I-dependent and/or IGF-I-independent mechanisms. This Translational Review summarizes the role of IGF-I and IGFBP-3 in the context of allergic airway disease, and discusses the therapeutic potential of various strategies targeting the IGF-I and IGFBP-3 signaling pathways for the management of asthma.
Collapse
Affiliation(s)
- Hyun Lee
- Department of Internal Medicine and Research Center for Pulmonary Disorders, Chonbuk National University Medical School, Jeonju, South Korea
| | - So Ri Kim
- Department of Internal Medicine and Research Center for Pulmonary Disorders, Chonbuk National University Medical School, Jeonju, South Korea
| | - Youngman Oh
- Department of Pathology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia; and
| | - Seong Ho Cho
- Division of Allergy–Immunology, Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
| | - Robert P. Schleimer
- Division of Allergy–Immunology, Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
| | - Yong Chul Lee
- Department of Internal Medicine and Research Center for Pulmonary Disorders, Chonbuk National University Medical School, Jeonju, South Korea
| |
Collapse
|
7
|
Fidler MJ, Shersher DD, Borgia JA, Bonomi P. Targeting the insulin-like growth factor receptor pathway in lung cancer: problems and pitfalls. Ther Adv Med Oncol 2012; 4:51-60. [PMID: 22423264 PMCID: PMC3296080 DOI: 10.1177/1758834011427576] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The insulin-like growth factor (IGF) pathway is a complex pathway involving interactions between membrane-bound receptors, ligands, binding proteins, downstream effectors, and other receptor tyrosine kinase signaling cascades. The IGF pathway has been identified as a potential therapeutic target in non-small cell lung cancer (NSCLC) based on the following provocative factors. Preclinical observations in NSCLC have shown that this pathway is involved in tumor cell proliferation, survival, and invasiveness. In addition, IGF-1R protein expression is found in a significant number of non-small cell tumor specimens. Initial therapeutic efforts involved the development of monoclonal antibodies and tyrosine kinase inhibitors that target IGF-1R, a transmembrane receptor tyrosine kinase. Enthusiasm for targeting this pathway increased when a randomized phase II study showed that combining an anti-IGF-1R monoclonal antibody (figitumumab) with a platinum doublet resulted in a higher response rate and trends for superior progression-free survival and overall survival. Subsequently, a phase III study failed to confirm the promising results observed in the phase II trial. Currently, investigators are studying different monoclonal antibodies and tyrosine kinases targeting IGF-1R. In unselected patients, results presented thus far do not suggest efficacy of this agent. However, retrospective subgroup analyses suggest that circulating IGF-1 levels might identify patients who could benefit from treatment with an IGF-1R monoclonal antibody and may warrant further exploratory studies for predictive molecular markers. The purpose of this paper is to briefly discuss the IGF pathway and its relationship with other signaling pathways in lung cancer and to review the ongoing IGF clinical trials and efforts to identify predictive molecular markers.
Collapse
Affiliation(s)
- Mary Jo Fidler
- Section of Medical Oncology, Rush University Medical Center, 1725 West Harrison Street, Suite 821, Chicago, IL 60612, USA
| | | | | | | |
Collapse
|
8
|
Worthmann K, Peters I, Kümpers P, Saleem M, Becker JU, Agustian PA, Achenbach J, Haller H, Schiffer M. Urinary excretion of IGFBP-1 and -3 correlates with disease activity and differentiates focal segmental glomerulosclerosis and minimal change disease. Growth Factors 2010; 28:129-38. [PMID: 20102313 DOI: 10.3109/08977190903512594] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The glomerular microenvironment is influenced by circulating growth factors that are filtered from the blood stream and pass the glomerular filtration barrier. In this study, we wanted to explore the role of IGF-binding proteins (IGFBPs) in two diseases that concern podocytes. We analyzed glomerular expression and urinary excretion of IGFBP-1, -2, and -3 in patients with focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD). We found that patients with active FSGS excrete high amounts of podocalyxin positive cells as well as IGFBP-1 and -3. In human podocytes, we can induce mRNA expression of IGFBP-3 in response to TGF-beta and in human microvascular endothelial cells expression of IGFBP-1 and -3 in response to TGF-beta and Bradykinin. We conclude that the local expression of IGFBPs in podocytes and endothelial cells might contribute to the pathogenesis of glomerular disease and that IGFBP-1 and -3 are potential non-invasive markers of FSGS.
Collapse
Affiliation(s)
- Kirstin Worthmann
- Department of Medicine/Nephrology, Hannover Medical School, Carl Neuberg Street 1, Hannover, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Qin LQ, He K, Xu JY. Milk consumption and circulating insulin-like growth factor-I level: a systematic literature review. Int J Food Sci Nutr 2009; 60 Suppl 7:330-40. [PMID: 19746296 DOI: 10.1080/09637480903150114] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Studies suggest that the circulating insulin-like growth factor I (IGF-I) level is positively associated with the prostate cancer risk. The association of milk consumption and circulating IGF-I level has been examined in epidemiological studies with inconsistent results. We conducted a systematic literature review to summarize and quantify the current evidence for milk or dairy product consumption and the circulating IGF-I level. We searched relevant papers published in English up to March 2009 in various databases. Fifteen cross-sectional studies and eight randomized controlled trials were finally identified. Ten cross-sectional studies showed statistically positive correlation between milk consumption and the circulating IGF-I level. Randomized controlled trials indicated that the circulating IGF-I level was significantly higher in the milk intervention group. After meta-analysis, the weighted mean difference of the circulating IGF-I level was 13.8 ng/ml (95% confidence interval: 6.1-21.5 ng/ml) comparing the intervention group with the control group. The current evidence suggests that milk consumption may increase the circulating IGF-I level.
Collapse
Affiliation(s)
- Li-Qiang Qin
- Department of Nutrition and Food Hygiene, School of Radiation Medicine and Public Health, Medical College of Soochow University, Suzhou, China.
| | | | | |
Collapse
|
10
|
Jogie-Brahim S, Feldman D, Oh Y. Unraveling insulin-like growth factor binding protein-3 actions in human disease. Endocr Rev 2009; 30:417-37. [PMID: 19477944 PMCID: PMC2819737 DOI: 10.1210/er.2008-0028] [Citation(s) in RCA: 230] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The IGF system plays critical roles in somatic growth in an endocrine fashion (somatomedin hypothesis) as well as proliferation and differentiation of normal and malignant cells in a paracrine/autocrine fashion. IGFBP-3 is known to modulate the actions of IGFs in circulation as well as the immediate extracellular environment. Interestingly, apart from the ability to inhibit or enhance IGF actions, IGFBP-3 also exhibits very clear, distinct biological effects independent of the IGF/IGF-I receptor axis. Over the past decade it has become widely appreciated that IGF/IGF-IR-independent actions of IGFBP-3 (antiproliferative and proapoptotic effects) contribute to improving the pathophysiology of a variety of human diseases, such as cancer, diabetes, and malnutrition. Recent studies have implicated interaction of IGFBP-3 with a variety of proteins or signaling cascades critical to cell cycle control and apoptosis; however, the actual mechanism of IGFBP-3 action is still unclear. This review reinforces the concept in support of the IGF/IGF-IR axis-independent actions of IGFBP-3 and delineates potential underlying mechanisms involved and subsequent biological significance, focusing in particular on functional binding partners and the clinical significance of IGFBP-3 in the assessment of cancer risk.
Collapse
Affiliation(s)
- Sherryline Jogie-Brahim
- Department of Pathology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298-0662, USA
| | | | | |
Collapse
|
11
|
Diorio C, Brisson J, Bérubé S, Pollak M. Intact and total insulin-like growth factor-binding protein-3 (IGFBP-3) levels in relation to breast cancer risk factors: a cross-sectional study. Breast Cancer Res 2008; 10:R42. [PMID: 18471292 PMCID: PMC2481489 DOI: 10.1186/bcr2093] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 05/02/2008] [Accepted: 05/09/2008] [Indexed: 11/25/2022] Open
Abstract
Introduction Levels of insulin-like growth factor (IGF)-I and its main binding protein (IGFBP-3) have been associated with breast cancer risk among premenopausal women. However, associations of IGFBP-3 levels with breast cancer risk have been inconsistent, possibly due to the different predominant forms of circulating IGFBP-3 (intact versus fragmented) that were measured in these studies. Here, we examine the association of breast cancer risk factors with intact and total IGFBP-3 levels. Methods This cross-sectional study includes 737 premenopausal women recruited at screening mammography. Plasma intact and total IGFBP-3 and IGF-I levels were measured by enzyme-linked immunosorbent assay methods. Percent and absolute breast density were estimated using a computer-assisted method. The associations were evaluated using generalized linear models and Pearson (r) or Spearman (rs) partial correlation coefficients. Results Means ± standard deviations of intact and total IGFBP-3 levels (ng/mL) were 1,044 ± 234 and 4,806 ± 910, respectively. Intact and total IGFBP-3 levels were correlated with age and smoking. Levels of intact IGFBP-3 were negatively correlated with waist-to-hip ratio (WHR) (r = -0.128; P = 0.0005), parity (rs = -0.078; P = 0.04), and alcohol intake (r = -0.137; P = 0.0002) and positively correlated with energy intake (r = 0.075; P = 0.04). In contrast, total IGFBP-3 levels were positively correlated with WHR (r = 0.115; P = 0.002), parity (rs = 0.089; P = 0.02), body mass index (BMI) (r = 0.115; P = 0.002), physical activity (r = 0.118; P = 0.002), and IGF-I levels (r = 0.588; P < 0.0001) and negatively correlated with percent or absolute breast density (r = -0.095; P = 0.01 and r = -0.075; P = 0.04, respectively). Conclusion Our data show that associations of some breast cancer risk factors with intact levels of IGFBP-3 are different from those with total (intact and fragmented) IGFBP-3 levels. These findings suggest that different molecular forms of IGFBP-3 may bear different relations to premenopausal breast cancer risk.
Collapse
Affiliation(s)
- Caroline Diorio
- McGill University, Breast Cancer Functional Genomics Group and McGill Centre for Bioinformatics, 3775 University Street, Montreal, QC H3A 2B4, Canada.
| | | | | | | |
Collapse
|
12
|
Veldhuis JD, Roemmich JN, Richmond EJ, Rogol AD, Lovejoy JC, Sheffield-Moore M, Mauras N, Bowers CY. Endocrine control of body composition in infancy, childhood, and puberty. Endocr Rev 2005; 26:114-46. [PMID: 15689575 DOI: 10.1210/er.2003-0038] [Citation(s) in RCA: 273] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Body composition exhibits marked variations across the early human lifetime. The precise physiological mechanisms that drive such developmental adaptations are difficult to establish. This clinical challenge reflects an array of potentially confounding factors, such as marked intersubject differences in tissue compartments; the incremental nature of longitudinal intrasubject variations in body composition; technical limitations in quantitating the unobserved mass of mineral, fat, water, and muscle ad seriatim; and the multifold contributions of genetic, dietary, environmental, hormonal, nutritional, and behavioral signals to physical and sexual maturation. From an endocrine perspective (reviewed here), gonadal sex steroids and GH/IGF-I constitute prime determinants of evolving body composition. The present critical review examines hormonal regulation of body composition in infancy, childhood, and puberty.
Collapse
Affiliation(s)
- Johannes D Veldhuis
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Mayo Medical and Graduate Schools of Medicine, General Clinical Research Center, Mayo Clinic, Rochester, Minnesota 55905, USA.
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Yan X, Forbes BE, McNeil KA, Baxter RC, Firth SM. Role of N- and C-terminal residues of insulin-like growth factor (IGF)-binding protein-3 in regulating IGF complex formation and receptor activation. J Biol Chem 2004; 279:53232-40. [PMID: 15485880 DOI: 10.1074/jbc.m409345200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-like growth factor-binding protein-3 (IGFBP-3), the major IGFBP in the circulation, sequesters IGF in a stable ternary complex with the acid-labile subunit. The high affinity IGF-binding site is proposed to reside within an N-terminal hydrophobic domain in IGFBP-3, but C-terminal residues have also been implicated in the homologous protein IGFBP-5. We have mutated in various combinations Leu(77), Leu(80), and Leu(81) in the N terminus and Gly(217) and Gln(223) in the C terminus of IGF-BP-3. All mutants retained immunoreactivity toward a polyclonal IGFBP-3 antibody, whereas IGF ligand blotting showed that all of the mutants had reduced binding to IGFs. Both solution IGF binding assays and BIAcore analysis indicated that mutations to the N-terminal region caused greater reduction in IGF binding activity than C-terminal mutations. The combined N- and C-terminal mutants showed undetectable binding to IGF-I but retained <10% IGF-II binding activity. Reduced ternary complex formation was seen only in mutants that had considerably reduced IGF-I binding, consistent with previous studies indicating that the binary IGF.IGFBP-3 complex is required for acid-labile subunit binding. Decreased IGF binding was also reflected in the inability of the mutants to inhibit IGF-I signaling in IGF receptor overexpressing cells. However, when present in excess, IGFBP-3 analogs defined as non-IGF-binding by biochemical assays could still inhibit IGF signaling. This suggests that residual binding activity of IGFBP-3 mutants may still be sufficient to inhibit IGF biological activity and questions the use of such analogs to study IGF-independent effects of IGFBP-3.
Collapse
Affiliation(s)
- Xiaolang Yan
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St. Leonards, New South Wales 2065, Australia
| | | | | | | | | |
Collapse
|
14
|
Abstract
Since their initial discovery over 25 years ago as IGF carrier proteins, the insulin-like growth factor binding protein (IGFBP) family has grown to six members, ranging in size from 216 to 289 amino acids. The assumption over the years has been that this family of proteins, having higher affinities for IGF-I and IGF-II than does the IGF-IR, serves to block access of these ligands to the receptor. Although the need for such regulatory proteins is consistent with the constitutive secretion of IGFs from many cell types, it is not surprising that additional functions have begun to be uncovered for these proteins. This review will examine new and old actions of the IGFBPs from a biochemical and cell biological perspective.
Collapse
Affiliation(s)
- Steven A Rosenzweig
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Hollings Cancer Center, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29403, USA.
| |
Collapse
|
15
|
London CA, Sekhon HS, Arora V, Stein DA, Iversen PL, Devi GR. A novel antisense inhibitor of MMP-9 attenuates angiogenesis, human prostate cancer cell invasion and tumorigenicity. Cancer Gene Ther 2004; 10:823-32. [PMID: 14605668 DOI: 10.1038/sj.cgt.7700642] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Androgen deprivation therapy causes a paradoxical elevation of matrix metalloproteinases (MMPs) including MMP-9 resulting in aggressive tumor phenotype in many patients with prostate cancer. In this study, we have evaluated a novel antisense phosphorodiamidate Morpholino oligomer (PMO) targeted against MMP-9 in models of angiogenesis and in human prostate xenograft in athymic mice. The treatment of androgen-independent DU145 human prostate cells with a 21-mer MMP-9 antisense PMO caused a dose-dependent inhibition of cell proliferation compared to scrambled or MMP-2 antisense PMO at similar concentrations. This was associated with decreases in MMP-9 expression, gelatinolytic activity and increased stability of the insulin-like growth factor-binding protein (IGFBP-3), a proapoptotic factor and MMP-9 substrate. In vitro invasion assays revealed a 40-60% inhibition of DU145 cell invasion in the presence of 25 microM MMP-9 antisense PMO. A significant decrease in endothelial cell migration and vascularization was observed in the Matrigel plug assay in mice when treated intraperitoneally with 300 microg/day MMP-9 antisense for 21 days. In the highly vascular DU145 tumor xenografts, MMP-9 inhibition caused decreased tumor growth with regression in 50% of the animals. Histological analysis revealed increased apoptosis and fibrous tissue deposits in the MMP-9 antisense-treated tumors compared to the scrambled and saline controls. No apparent toxicity or mortality was associated with the MMP-9 PMO treatment. In summary, the MMP-9 antisense PMO inhibited in vitro prostate cancer cell proliferation, invasion and in vivo angiogenesis. These data establish the feasibility of developing a site-directed, nontoxic antisense therapeutic agent for inhibiting local invasion and metastasis.
Collapse
Affiliation(s)
- Carla A London
- AVI BioPharma Inc., 4575 SW Research Way, Suite 200, Corvallis, Oregon 97333, USA
| | | | | | | | | | | |
Collapse
|
16
|
Huang SS, Tang FM, Huang YH, Liu IH, Hsu SC, Chen ST, Huang JS. Cloning, expression, characterization, and role in autocrine cell growth of cell surface retention sequence binding protein-1. J Biol Chem 2003; 278:43855-69. [PMID: 12912978 DOI: 10.1074/jbc.m306411200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cell surface retention sequence binding protein-1 (CRSBP-1) is a cell surface binding protein for the cell surface retention sequence (CRS) motif of the v-sis gene product (platelet-derived growth factor-BB). It has been shown to be responsible for cell surface retention of the v-sis gene product in v-sis-transformed cells (fibroblasts) and has been hypothesized to play a role in autocrine growth and transformation of these cells. Here we demonstrate that the CRSBP-1 cDNA cloned from bovine liver libraries encodes a 322-residue type I membrane protein containing a 23-residue signal peptide, a 215-residue cell surface domain, a 21-residue transmembrane domain, and a 63-residue cytoplasmic domain. CRSBP-1 expressed in transfected cells is an approximately 120-kDa disulfide-linked homodimeric glycoprotein and exhibits dual ligand (CRS-containing growth regulators (v-sis gene product and insulin-like growth factor binding protein-3, IGFBP-3) and hyaluronic acid) binding activity. CRSBP-1 overexpression (by stable transfection of cells with CRSBP-1 cDNA) enhances autocrine loop signaling, cell growth, and tumorigenicity (in mice) of v-sis-transformed cells. CRSBP-1 expression also enhances autocrine cell growth mediated by IGFBP-3 in human lung carcinoma cells (H1299 cells), which express very little, if any, endogenous CRSBP-1 and exhibits a mitogenic response to exogenous IGFBP-3, stably transfected with IGFBP-3 cDNA. However, CRSBP-1 overexpression does not affect growth of normal and transformed cells that do not produce these CRS-containing growth regulators. These results suggest that CRSBP-1 plays a role in autocrine regulation of cell growth mediated by growth regulators containing CRS.
Collapse
Affiliation(s)
- Shuan Shian Huang
- Departments of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA.
| | | | | | | | | | | | | |
Collapse
|
17
|
Kricker JA, Towne CL, Firth SM, Herington AC, Upton Z. Structural and functional evidence for the interaction of insulin-like growth factors (IGFs) and IGF binding proteins with vitronectin. Endocrinology 2003; 144:2807-15. [PMID: 12810534 DOI: 10.1210/en.2002-221086] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Previous studies demonstrated that IGF-II binds directly to vitronectin (VN), whereas IGF-I binds poorly. However, binding of VN to integrins has been demonstrated to be essential for a range of IGF-I-stimulated biological effects, including IGF binding protein (IGFBP)-5 production, IGF type-1 receptor autophosphorylation, and cell migration. Thus, we hypothesized that a link between IGF-I and VN must occur and may be mediated through IGFBPs. This was tested using competitive binding assays with VN and (125)iodine-labeled IGFs in the absence and presence of IGFBPs. IGFBP-4, IGFBP-5, and nonglycosylated IGFBP-3 were shown to significantly enhance binding of IGF-I to VN, whereas IGFBP-2 and glycosylated IGFBP-3 had a smaller effect. Furthermore, binding studies with analogs indicate that glycosylation status and the heparin-binding domain of IGFBP-3 are important in this interaction. To examine the functional significance of IGFs binding to VN, cell migration in MCF7 cells was measured and found to be enhanced when VN was prebound to IGF-I in the presence of IGFBP-5. The effect required IGF:IGFBP:VN complex formation; this was demonstrated by use of a non-IGFBP-binding IGF-I analog. Together, these data indicate the importance of IGFBPs in modulating IGF-I binding to VN and that this binding has functional consequences in cells.
Collapse
Affiliation(s)
- Jennifer A Kricker
- Tissue BioRegeneration and Integration Program, School of Life Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
| | | | | | | | | |
Collapse
|
18
|
Abstract
In addition to their roles in IGF transport, the six IGF-binding proteins (IGFBPs) regulate cell activity in various ways. By sequestering IGFs away from the type I IGF receptor, they may inhibit mitogenesis, differentiation, survival, and other IGF-stimulated events. IGFBP proteolysis can reverse this inhibition or generate IGFBP fragments with novel bioactivity. Alternatively, IGFBP interaction with cell or matrix components may concentrate IGFs near their receptor, enhancing IGF activity. IGF receptor-independent IGFBP actions are also increasingly recognized. IGFBP-1 interacts with alpha(5)beta(1) integrin, influencing cell adhesion and migration. IGFBP-2, -3, -5, and -6 have heparin-binding domains and can bind glycosaminoglycans. IGFBP-3 and -5 have carboxyl-terminal basic motifs incorporating heparin-binding and additional basic residues that interact with the cell surface and matrix, the nuclear transporter importin-beta, and other proteins. Serine/threonine kinase receptors are proposed for IGFBP-3 and -5, but their signaling functions are poorly understood. Other cell surface IGFBP-interacting proteins are uncharacterized as functional receptors. However, IGFBP-3 binds and modulates the retinoid X receptor-alpha, interacts with TGFbeta signaling through Smad proteins, and influences other signaling pathways. These interactions can modulate cell cycle and apoptosis. Because IGFBPs regulate cell functions by diverse mechanisms, manipulation of IGFBP-regulated pathways is speculated to offer therapeutic opportunities in cancer and other diseases.
Collapse
Affiliation(s)
- Sue M Firth
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St Leonards, New South Wales 2065, Australia
| | | |
Collapse
|
19
|
Schedlich LJ, Graham LD. Role of insulin-like growth factor binding protein-3 in breast cancer cell growth. Microsc Res Tech 2002; 59:12-22. [PMID: 12242693 DOI: 10.1002/jemt.10173] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The mitogenic effects of insulin-like growth factors (IGFs) are regulated by a family of insulin-like growth factor binding proteins (IGFBPs). One member of this family, IGFBP-3, mediates the growth-inhibitory and apoptosis-inducing effects of a number of growth factors and hormones such as transforming growth factor-beta, retinoic acid, and 1,25-dihydroxyvitamin D3. IGFBP-3 may act in an IGF-dependent manner by attenuating the interaction of pericellular IGFs with the type-I IGF receptor. It may also act in an IGF-independent manner by initiating intracellular signaling from a cell surface receptor, or by direct nuclear action, or both. The possibility of a membrane-bound receptor is strengthened by recent studies which have identified members of the transforming growth factor-beta receptor family as having a role, either directly or indirectly, in signaling from the cell surface by IGFBP-3. A number of growth factors and hormones stimulate the expression and secretion of cellular IGFBP-3, which then signals from the cell surface to bring about some of the effects attributed to the primary agents. Within the cell, the apoptosis-inducing tumor suppressor, p53, can also induce IGFBP-3 expression and secretion. Since IGFBP-3 upregulates the cell cycle inhibitor, p21(Waf1), and increases the ratio of proapoptotic to antiapoptotic members of the Bcl family, it appears to exert the same effects on major downstream targets of cell signaling as p53 does. The nuclear localization of IGFBP-3 has been described in a number of cell types. IGFBP-3 may act to import IGFs or other nuclear localization signal-deficient signaling molecules into the nucleus. It may also act directly in the nucleus by enhancing the activity of retinoid X receptor-alpha and thereby promote apoptosis. All of the above phenomena will be discussed with particular emphasis on the growth of breast cancer cells.
Collapse
Affiliation(s)
- Lynette J Schedlich
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, Sydney, Australia.
| | | |
Collapse
|
20
|
Devi GR, Sprenger CC, Plymate SR, Rosenfeld RG. Insulin-like growth factor binding protein-3 induces early apoptosis in malignant prostate cancer cells and inhibits tumor formation in vivo. Prostate 2002; 51:141-52. [PMID: 11948969 DOI: 10.1002/pros.10068] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Insulin-like growth factor binding protein (IGFBP-3) levels are significantly reduced in malignant prostate epithelial cells. In this study, we evaluated the role of endogenous IGFBP-3 on prostate cancer cell growth and tumorigenesis. METHODS IGFBP-3 was re-expressed by stable transfection of human IGFBP-3 cDNA in a model of human prostate cancer, M12, a malignant subline in which IGFBP-3 levels are undetectable in comparison to the parent epithelial cell, P69. Effect of IGFBP-3 re-expression (M12-BP-3) on growth kinetics, morphology, propensity to apoptosis, and in vivo tumor formation were studied. RESULTS M12-BP-3 cells secreted IGFBP-3 and growth arrested at a cell density that was threefold lower than control cells and this was associated with marked alteration in cell morphology. Control cells when grown in conditioned media secreted by M12-BP-3 also showed altered morphology compared to when cultured in IGFBP-3-immunodepleted conditioned media. The M12-BP-3 clones showed altered mitochondrial membrane potential, increased PARP cleavage, increase in sub-G1 peak, decreased levels of neuron specific enolase, and decreased tumor formation in athymic, nude mice. CONCLUSIONS These data suggest that IGFBP-3 induces early apoptosis and has potential tumor suppressive effect in prostate cancer. Prostate 51: 141-152, 2002.
Collapse
Affiliation(s)
- Gayathri R Devi
- Department of Pediatrics, School of Medicine, Oregon Health Sciences University, Portland, Oregon, USA.
| | | | | | | |
Collapse
|
21
|
Forsten KE, Akers RM, San Antonio JD. Insulin-like growth factor (IGF) binding protein-3 regulation of IGF-I is altered in an acidic extracellular environment. J Cell Physiol 2001; 189:356-65. [PMID: 11748593 DOI: 10.1002/jcp.10033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
While extracellular acidification within solid tumors is well-documented, how reduced pH impacts regulation of insulin-like growth factor-I (IGF-I) has not been studied extensively. Because IGF-I receptor binding is affected by IGF binding proteins (IGFBPs), we examined how pH impacted IGFBP-3 regulation of IGF-I. IGF-I binding in the absence of IGFBP-3 was diminished at reduced pH. Addition of IGFBP-3 reduced IGF-I cell binding at pH 7.4 but increased surface association at pH 5.8. This increase in IGF-I binding at pH 5.8 corresponded with an increase in IGFBP-3 cell association. This, however, was not due to an increase in affinity of IGFBP-3 for heparin at reduced pH although both heparinase III treatment and heparin addition reduced IGFBP-3 enhancement of IGF-I binding. An increase in IGF-I binding to IGFBP-3, though, was seen at reduced pH using a cell-free assay. We hypothesize that the enhanced binding of IGF-I at pH 5.8 is facilitated by increased association of IGFBP-3 at this pH and that the resulting cell associated IGF-I is IGFBP-3 and not IGF-IR bound. Increased internalization and nuclear association of IGF-I at pH 5.8 in the presence of IGFBP-3 was evident, yet cell proliferation was reduced by IGFBP-3 at both pH 5.8 and 7.4 indicating that IGFBP-3-cell associated IGF-I does not signal the cell to proliferate and that the resulting transfer of bound IGF-I from IGF-IR to IGFBP-3 results in diminished proliferation. Solution binding of IGF-I by IGFBP-3 is one means by which IGF-I-induced proliferation is inhibited. Our work suggests that an alternative pathway exists by which IGF-I and IGFBP-3 both associate with the cell surface and that this association inhibits IGF-I-induced proliferation.
Collapse
Affiliation(s)
- K E Forsten
- Department of Chemical Engineering, Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA.
| | | | | |
Collapse
|
22
|
Buckway CK, Wilson EM, Ahlsén M, Bang P, Oh Y, Rosenfeld RG. Mutation of three critical amino acids of the N-terminal domain of IGF-binding protein-3 essential for high affinity IGF binding. J Clin Endocrinol Metab 2001; 86:4943-50. [PMID: 11600567 DOI: 10.1210/jcem.86.10.7936] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The N-terminal domain is conserved in all members of the IGF-binding protein superfamily. Most recently, studies have demonstrated the importance of an IGF-binding protein N-terminal hydrophobic pocket for IGF binding. To examine more critically the amino acids important for IGF binding within the full-length IGF-binding protein-3 protein while minimizing changes in the tertiary structure, we targeted residues I56, L80, and L81 within the proposed hydrophobic pocket for mutation. With a single change at these sites to the nonconserved glycine there was a notable decrease in binding. A greater reduction was seen when both L80 and L81 were substituted with glycine, and complete loss of affinity for IGF-I and IGF-II occurred when all three targeted amino acids were changed to glycine. Furthermore, the ability of the IGF-binding protein-3 mutants to inhibit IGF-I-stimulated phosphorylation of its receptor was a reflection of their affinity for IGF, with the lowest affinity mutants having the least inhibitory effect. These studies, thus, support the hypothesis that an N-terminal hydrophobic pocket is the primary site of high affinity binding of IGF to IGF-binding protein-3. The mutants provide a tool for future studies directed at IGF-dependent and IGF-independent actions of IGF-binding protein-3.
Collapse
Affiliation(s)
- C K Buckway
- Department of Pediatrics, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97201, USA.
| | | | | | | | | | | |
Collapse
|
23
|
Devi GR, Graham DL, Oh Y, Rosenfeld RG. Effect of IGFBP-3 on IGF- and IGF-analogue-induced insulin-like growth factor-I receptor (IGFIR) signalling. Growth Horm IGF Res 2001; 11:231-239. [PMID: 11735239 DOI: 10.1054/ghir.2001.0231] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Insulin-like growth factor binding protein-3 (IGFBP-3) binds IGF-I and IGF-II with high affinity, at least an order of magnitude higher than the affiniy of the IGFs for the IGFIR. It has been hypothesized that IGFBP-3 inhibits IGF binding to the IGFIR via a mechanism independent of its ability to sequester IGFs. In the present study, we examined the effects of IGFBP-3 and its proteolytic fragments on the initial events of the IGFIR signalling pathway. IGFBP-3 inhibited IGF-I-, IGF-II-, Des(1-3)IGF-I- and Long(R3)IGF-I-induced IGFIR phosphorylation in a dose-dependent manner at similar concentration range but not QAYL-induced IGFIR-P. The((1-97))IGFBP-3 fragment was able to inhibit only IGF-I-induced IGFIR-P. The((1-97))IGFBP-3 fragment but not intact IGFBP-3 inhibited insulin-induced IGFIR-P. Monolayer cross-linking with [(125)I]IGFBP-3 indicated that there is no direct interaction of IGFBP-3 with the IGFIR. This study demonstrates that the effect on the initial step of IGFIR signalling by IGFBP-3 is largely due to its ability to sequester IGF and the IGF analogues in the extracellular milieu and not the result of any interaction of IGFBP-3 with the IGFIR or a mechanism independent of its ability to bind IGFs.
Collapse
Affiliation(s)
- G R Devi
- Department of Pediatrics, School of Medicine, Oregon Health Sciences University, Portland, OR 97201-3042, USA.
| | | | | | | |
Collapse
|