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Development of a Sensitive Bioassay for the Analysis of IGF-Related Activation of AKT/mTOR Signaling in Biological Matrices. Cells 2021; 10:cells10030482. [PMID: 33668197 PMCID: PMC7995968 DOI: 10.3390/cells10030482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 02/15/2021] [Accepted: 02/21/2021] [Indexed: 12/11/2022] Open
Abstract
The bioactivity of the IGF system is not a function of isolated hormone concentrations in a given biological matrix. Instead, the biological activities of IGFs are regulated by IGFBPs, IGFBP proteases, and inhibitors of IGFBP proteases. Therefore, assays based on IGF-related bioactivity may describe functions of the complete IGF system in a given biological matrix. Of particular interest are the IGF system effects on the AKT/mTOR pathway, as a dominant system for controlling growth, metabolism, and aging. In order to improve the sensitivity of IGF-dependent bioactivity, we made use of the known short-term and enhancing effects of IGFBP2 on the intracellular PI3K pathway. As a specific readout of this pathway, and further as a marker of the mTOR pathway, we assessed the phosphorylation of AKT-Ser473. Preincubation using IGFBP2 enhanced IGF1-dependent AKT-Ser473 phosphorylation in our experimental system. The assay's specificity was demonstrated by inhibition of IGF1 receptors outside or inside the cell, using antiserum or small molecule inhibitors, which reduced AKT phosphorylation in response to exogenous IGF1 (p < 0.05). The maximal response of AKT phosphorylation was recorded 15 to 60 min after the addition of IGF1 to cell monolayers (p < 0.001). In our cellular system, insulin induced AKT phosphorylation only at supra-physiological concentrations (µM). Using this novel assay, we identified the differential biological activity of the IGF system in AKT-Ser473 phosphorylation in serum (mouse, naked mole rat, and human), in cerebrospinal fluid (human), and in colostrum or mature milk samples (dairy cow). We have developed a sensitive and robust bioassay to assess the IGF-related activation of the AKT/mTOR pathway. The assay works efficiently and does not require expensive cell culture systems. By using capillary immuno-electrophoresis, the readout of IGF-related bioactivity is substantially accelerated, requiring a minimum of hands-on time. Importantly, the assay system is useful for studying IGF-related activity in the AKT/mTOR pathway in a broad range of biological matrices.
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Frystyk J, Teran E, Gude MF, Bjerre M, Hjortebjerg R. Pregnancy-associated plasma proteins and Stanniocalcin-2 - Novel players controlling IGF-I physiology. Growth Horm IGF Res 2020; 53-54:101330. [PMID: 32693362 DOI: 10.1016/j.ghir.2020.101330] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 06/04/2020] [Accepted: 06/06/2020] [Indexed: 10/23/2022]
Abstract
IGF-I was originally discovered as a GH-dependent growth factor stimulating longitudinal growth. Currently, however, it has become evident that the biological activities of IGF-I extend well beyond those of a simple growth factor and impact such processes as insulin sensitivity, aging, cancer and cardiovascular disease. The vast majority of IGF-I is tightly bound to IGF-binding proteins (IGFBPs), which renders IGF-I unable to stimulate the IGF-I receptor (IGF-IR) in vivo. This binding means that liberation of IGF-I from the IGFBPs is an important step controlling IGF-I action. In this context, IGFBP-cleaving enzymes appear to play a key role. Enzymatic cleavage of the IGFBPs markedly lowers their ligand affinity, and as a consequence, IGF-I becomes liberated and hence available for stimulation of the IGF-IR. Two of the best-characterized IGFBP-cleaving enzymes are pregnancy-associated plasma protein-A (PAPP-A) and its paralog PAPP-A2. The two enzymes (often referred to as pappalysins) regulate the liberation of IGF-I in a highly controlled manner. PAPP-A is believed to act predominantly in tissues, serving to liberate IGF-I at the cell surface in close proximity to the IGF-IR. In keeping with this notion, mice lacking PAPP-A exhibit reduced body size, despite having normal circulating IGF-I concentrations. In contrast, human findings indicate that altered PAPP-A2 activity changes circulating IGF-I concentrations, although PAPP-A2 is also present in high concentrations in tissues. Thus, PAPP-A2 appears to impact circulating, as well as tissue, IGF-I activity. The enzymatic activity of PAPP-A and PAPP-A2 was recently discovered to be regulated by the protein Stanniocalcin-2 (STC2). By binding to the enzymatic sites of PAPP-A and PAPP-A2, STC2 inhibits their activity. To date, the majority of findings demonstrating the ability of pappalysins and STC2 to regulate IGF-I action are from preclinical studies. However, clinical studies are now beginning to emerge. In this review, we will summarize our data on STC2, PAPP-A and PAPP-A2 in humans. These results indicate that pappalysins and STC2 constitute an important IGF-I activity-regulating system that warrants further investigation.
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Affiliation(s)
- Jan Frystyk
- Endocrine Research Unit, Department of Endocrinology, Odense University Hospital & Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark.
| | - Enrique Teran
- Colegio de Ciencias de la Salud, Universidad San Francisco de Quito, Quito, Ecuador
| | - Mette Faurholdt Gude
- Medical Research Laboratory, Department of Clinical Medicine, Health, Aarhus University, Aarhus, Denmark
| | - Mette Bjerre
- Medical Research Laboratory, Department of Clinical Medicine, Health, Aarhus University, Aarhus, Denmark
| | - Rikke Hjortebjerg
- Endocrine Research Unit, Department of Endocrinology, Odense University Hospital & Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark; Steno Diabetes Center Odense (SDCO), Odense University Hospital, Odense, Denmark
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Chen YM, Qi S, Perrino S, Hashimoto M, Brodt P. Targeting the IGF-Axis for Cancer Therapy: Development and Validation of an IGF-Trap as a Potential Drug. Cells 2020; 9:cells9051098. [PMID: 32365498 PMCID: PMC7290707 DOI: 10.3390/cells9051098] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 12/13/2022] Open
Abstract
The insulin-like growth factor (IGF)-axis was implicated in cancer progression and identified as a clinically important therapeutic target. Several IGF-I receptor (IGF-IR) targeting drugs including humanized monoclonal antibodies have advanced to phase II/III clinical trials, but to date, have not progressed to clinical use, due, at least in part, to interference with insulin receptor signaling and compensatory signaling by the insulin receptor (IR) isoform A that can bind IGF-II and initiate mitogenic signaling. Here we briefly review the current state of IGF-targeting biologicals, discuss some factors that may be responsible for their poor performance in the clinic and outline the stepwise bioengineering and validation of an IGF-Trap—a novel anti-cancer therapeutic that could bypass these limitations. The IGF-Trap is a heterotetramer, consisting of the entire extracellular domain of the IGF-IR fused to the Fc portion of human IgG1. It binds human IGF-I and IGF-II with a three-log higher affinity than insulin and could inhibit IGF-IR driven cellular functions such as survival, proliferation and invasion in multiple carcinoma cell models in vitro. In vivo, the IGF-Trap has favorable pharmacokinetic properties and could markedly reduce metastatic outgrowth of colon and lung carcinoma cells in the liver, outperforming IGF-IR and ligand-binding monoclonal antibodies. Moreover, IGF-Trap dose-response profiles correlate with their bio-availability profiles, as measured by the IGF kinase receptor-activation (KIRA) assay, providing a novel, surrogate biomarker for drug efficacy. Our studies identify the IGF-Trap as a potent, safe, anti-cancer therapeutic that could overcome some of the obstacles encountered by IGF-targeting biologicals that have already been evaluated in clinical settings.
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Affiliation(s)
- Yinhsuan Michely Chen
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada
- The Research Institute of the McGill University Health Center, Montreal, QC H4A 3J1, Canada
| | - Shu Qi
- The Research Institute of the McGill University Health Center, Montreal, QC H4A 3J1, Canada
| | - Stephanie Perrino
- The Research Institute of the McGill University Health Center, Montreal, QC H4A 3J1, Canada
| | - Masakazu Hashimoto
- The Research Institute of the McGill University Health Center, Montreal, QC H4A 3J1, Canada
- Department of Surgery, McGill University, Montreal, QC H3A 0G4, Canada
| | - Pnina Brodt
- Department of Medicine, Division of Experimental Medicine, McGill University, Montreal, QC H3A 0G4, Canada
- The Research Institute of the McGill University Health Center, Montreal, QC H4A 3J1, Canada
- Department of Surgery, McGill University, Montreal, QC H3A 0G4, Canada
- Department of Oncology, McGill University, Montreal, QC H3A 0G4, Canada
- Correspondence: ; Tel.: +1-514-934-1934
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Kallestrup M, Frystyk J, Espelund U, Hjortebjerg R, Tankisi H, Andersen H. PAPP-A activity is increased in cerebrospinal fluid from patients with diabetic polyneuropathy and correlates with peripheral nerve impairment. Growth Horm IGF Res 2019; 48-49:53-59. [PMID: 31670029 DOI: 10.1016/j.ghir.2019.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 09/29/2019] [Accepted: 10/08/2019] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Insulin-like growth factors (IGFs) have neuroprotective effects. IGF activity is partly controlled by pregnancy-associated plasma protein-A (PAPP-A), an enzyme which enhances IGF-action by cleavage of IGF-binding protein-4 (IGFBP-4). To study the role of PAPP-A and the IGF system in diabetic polyneuropathy (DPN), we measured immunoreactive (total) concentrations of IGF-I and IGF-II, bioactive IGF by cell-based bioassay, PAPP-A, as well as intact and PAPP-A-cleaved IGFBP-4 in cerebrospinal fluid (CSF) and serum from patients with type 2 diabetes (T2D) with and without DPN. DESIGN Twenty-three patients with T2D were included. Based on clinical examination, vibratory perception thresholds and nerve conduction studies, patients were diagnosed with (n = 9) or without (n = 14) DPN. RESULTS In CSF, PAPP-A activity, as estimated by IGFBP-4 fragment levels, was higher in patients with than without DPN (34.57 vs 13.79 μg/L, p = .003) and concentrations correlated with peripheral nerve impairment measures (r = 0.73, p < .01). Furthermore, serum bioactive IGF was lower in patients with than without DPN (0.8 vs 1.3 μg/L, p = .006) and correlated inversely to the severity of DPN (r = -0.67, p < .01). CONCLUSIONS In both CSF and serum, members of the IGF system correlated with measures of peripheral nerve impairment in patients with T2D. This supports a relationship between the IGF system and the development of DPN. Further studies are needed to clarify if these changes are causally linked to the pathogenesis of DPN.
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Affiliation(s)
- M Kallestrup
- Department of Neurology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark.
| | - J Frystyk
- Medical Research Laboratory, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark; Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Campusvej 55, 5000 Odense, Denmark; Department of Endocrinology, Odense University Hospital, Kløvervænget 6, 5000 Odense, Denmark
| | - U Espelund
- Medical Research Laboratory, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark
| | - R Hjortebjerg
- Medical Research Laboratory, Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark; The Danish Diabetes Academy, 5000 Odense, Denmark
| | - H Tankisi
- Department of Neurophysiology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark
| | - H Andersen
- Department of Neurology, Aarhus University Hospital, Palle Juul-Jensens Boulevard 165, 8200 Aarhus N, Denmark
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Vaniotis G, Moffett S, Sulea T, Wang N, Elahi SM, Lessard E, Baardsnes J, Perrino S, Durocher Y, Frystyk J, Massie B, Brodt P. Enhanced anti-metastatic bioactivity of an IGF-TRAP re-engineered to improve physicochemical properties. Sci Rep 2018; 8:17361. [PMID: 30478273 PMCID: PMC6255772 DOI: 10.1038/s41598-018-35407-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/07/2018] [Indexed: 01/22/2023] Open
Abstract
The insulin-like growth factor (IGF) axis has been implicated in the progression of malignant disease and identified as a clinically important therapeutic target. Several IGF-1 receptor (IGF-1R) targeting drugs including humanized monoclonal antibodies have advanced to phase II/III clinical trials, but to date, have not progressed to clinical use, due, at least in part, to interference with insulin receptor signalling. We previously reported on the production of a soluble fusion protein consisting of the extracellular domain of human IGF-1R fused to the Fc portion of human IgG1 (first generation IGF-TRAP) that bound human IGF-1 and IGF-2 with a 3 log higher affinity than insulin. We showed that the IGF-TRAP had potent anti-cancer activity in several pre-clinical models of aggressive carcinomas. Here we report on the re-engineering of the IGF-TRAP with the aim of improving physicochemical properties and suitability for clinical applications. We show that cysteine-serine substitutions in the Fc hinge region of IGF-TRAP eliminated high-molecular-weight oligomerized species, while a further addition of a flexible linker, not only improved the pharmacokinetic profile, but also enhanced the therapeutic profile of the IGF-TRAP, as evaluated in an experimental colon carcinoma metastasis model. Dose-response profiles of the modified IGF-TRAPs correlated with their bio-availability profiles, as measured by the IGF kinase-receptor-activation (KIRA) assay, providing a novel, surrogate biomarker for drug efficacy. This study provides a compelling example of structure-based re-engineering of Fc-fusion-based biologics for better manufacturability that also significantly improved pharmacological parameters. It identifies the re-engineered IGF-TRAP as a potent anti-cancer therapeutic.
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Affiliation(s)
- George Vaniotis
- Department of Surgery, McGill University, Montreal Quebec, Canada
| | - Serge Moffett
- Department of Surgery, McGill University, Montreal Quebec, Canada
| | - Traian Sulea
- Institute of Parasitology, McGill University, Montreal Quebec, Canada
- Human Health Therapeutics Research Centre, National Research Council Canada, Montreal Quebec, Canada
| | - Ni Wang
- Department of Surgery, McGill University, Montreal Quebec, Canada
| | - S Mehdy Elahi
- Human Health Therapeutics Research Centre, National Research Council Canada, Montreal Quebec, Canada
| | - Etienne Lessard
- Human Health Therapeutics Research Centre, National Research Council Canada, Montreal Quebec, Canada
| | - Jason Baardsnes
- Human Health Therapeutics Research Centre, National Research Council Canada, Montreal Quebec, Canada
| | | | - Yves Durocher
- Human Health Therapeutics Research Centre, National Research Council Canada, Montreal Quebec, Canada
| | - Jan Frystyk
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Bernard Massie
- Human Health Therapeutics Research Centre, National Research Council Canada, Montreal Quebec, Canada
| | - Pnina Brodt
- Department of Surgery, McGill University, Montreal Quebec, Canada.
- Department of Medicine, McGill University, Montreal Quebec, Canada.
- Department of Oncology, McGill University, Montreal Quebec, Canada.
- Cancer Research Program, Research Institute of the McGill University Health Center, Montreal Quebec, Canada.
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Dichtel LE, Bjerre M, Schorr M, Bredella MA, Gerweck AV, Russell BM, Frystyk J, Miller KK. The effect of growth hormone on bioactive IGF in overweight/obese women. Growth Horm IGF Res 2018; 40:20-27. [PMID: 29679919 PMCID: PMC6426149 DOI: 10.1016/j.ghir.2018.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/19/2018] [Accepted: 03/09/2018] [Indexed: 10/17/2022]
Abstract
OBJECTIVE Overweight/obesity is characterized by decreased growth hormone (GH) secretion whereas circulating IGF-I levels are less severely reduced. Yet, the activity of the circulating IGF-system appears to be normal in overweight/obese subjects, as estimated by the ability of serum to activate the IGF-I receptor in vitro (bioactive IGF). We hypothesized that preservation of bioactive IGF in overweight/obese women is regulated by an insulin-mediated suppression of IGF-binding protein-1 (IGFBP-1) and IGFBP-2, and by suppression of IGFBP-3, mediated by low GH. We additionally hypothesized that increases in bioactive IGF would drive changes in body composition with low-dose GH administration. DESIGN Cross-sectional analysis and 3-month interim analysis of a 6-month randomized, placebo-controlled study of GH administration in 50 overweight/obese women without diabetes mellitus. Bioactive IGF (kinase receptor activation assay) and body composition (DXA) were measured. RESULTS Prior to treatment, IGFBP-3 (r = -0.33, p = 0.02), but neither IGFBP-1 nor IGFBP-2, associated inversely with bioactive IGF. In multivariate analysis, lower IGFBP-3 correlated with lower peak stimulated GH (r = 0.45, p = 0.05) and higher insulin sensitivity (r = -0.74, p = 0.003). GH administration resulted in an increase in mean serum IGF-I concentrations (144 ± 56 to 269 ± 66 μg/L, p < 0.0001) and bioactive IGF (1.29 ± 0.39 to 2.60 ± 1.12 μg/L, p < 0.0001). The treatment-related increase in bioactive IGF, but not total IGF-I concentration, predicted an increase in lean mass (r = 0.31, p = 0.03) and decrease in total adipose tissue/BMI (r = -0.43, p = 0.003). CONCLUSIONS Our data suggest that in overweight/obesity, insulin sensitivity and GH have opposing effects on IGF bioactivity through effects on IGFBP-3. Furthermore, increases in bioactive IGF, rather than IGF-I concentration, predicted GH administration-related body composition changes. CLINICAL TRIAL REGISTRATION NUMBER NCT00131378.
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Affiliation(s)
- Laura E Dichtel
- Neuroendocrine Unit, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States.
| | - Mette Bjerre
- Medical Research Lab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Melanie Schorr
- Neuroendocrine Unit, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States
| | - Miriam A Bredella
- Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States
| | - Anu V Gerweck
- Neuroendocrine Unit, Massachusetts General Hospital, Boston, MA, United States
| | - Brian M Russell
- Neuroendocrine Unit, Massachusetts General Hospital, Boston, MA, United States
| | - Jan Frystyk
- Medical Research Lab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Karen K Miller
- Neuroendocrine Unit, Massachusetts General Hospital/Harvard Medical School, Boston, MA, United States
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Sarem Z, Bumke-Vogt C, Mahmoud AM, Assefa B, Weickert MO, Adamidou A, Bähr V, Frystyk J, Möhlig M, Spranger J, Lieske S, Birkenfeld AL, Pfeiffer AFH, Arafat AM. Glucagon Decreases IGF-1 Bioactivity in Humans, Independently of Insulin, by Modulating Its Binding Proteins. J Clin Endocrinol Metab 2017; 102:3480-3490. [PMID: 28911141 PMCID: PMC6287397 DOI: 10.1210/jc.2017-00558] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 06/28/2017] [Indexed: 12/28/2022]
Abstract
CONTEXT Depending on its lipolytic activity, glucagon plays a promising role in obesity treatment. Glucagon-induced growth hormone (GH) release can promote its effect on lipid metabolism, although the underlying mechanisms have not been well-defined. OBJECTIVE The present study highlights the glucagon effect on the GH/insulinlike growth factor 1 (IGF-1)/IGF-binding protein (IGFBP) axis in vivo and in vitro, taking into consideration insulin as a confounding factor. MATERIALS AND METHODS In a double-blind, placebo-controlled study, we investigated changes in GH, IGFBP, and IGF-1 bioactivity after intramuscular glucagon administration in 13 lean controls, 11 obese participants, and 13 patients with type 1 diabetes mellitus (T1DM). The effect of glucagon on the transcription factor forkhead box protein O1 (FOXO1) translocation, the transcription of GH/IGF-1 system members, and phosphorylation of protein kinase B (Akt) was further investigated in vitro. RESULTS Despite unchanged total IGF-1 and IGFBP-3 levels, glucagon decreased IGF-1 bioactivity in all study groups by increasing IGFBP-1 and IGFBP-2. The reduction in IGF-1 bioactivity occurred before the glucagon-induced surge in GH. In contrast to the transient increase in circulating insulin in obese and lean participants, no change was observed in those with T1DM. In vitro, glucagon dose dependently induced a substantial nuclear translocation of FOXO1 in human osteosarcoma cells and tended to increase IGFBP-1 and IGFBP-2 gene expression in mouse primary hepatocytes, despite absent Akt phosphorylation. CONCLUSIONS Our data point to the glucagon-induced decrease in bioactive IGF-1 levels as a mechanism through which glucagon induces GH secretion. This insulin-independent reduction is related to increased IGFBP-1 and IGFBP-2 levels, which are most likely mediated via activation of the FOXO/mTOR (mechanistic target of rapamycin) pathway.
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Affiliation(s)
- Zeinab Sarem
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
- Department of Clinical Nutrition, German Institute of Human Nutrition
Potsdam-Rehbrücke, Nuthetal 14558, Germany
| | - Christiane Bumke-Vogt
- Department of Clinical Nutrition, German Institute of Human Nutrition
Potsdam-Rehbrücke, Nuthetal 14558, Germany
| | - Ayman M Mahmoud
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
- Department of Endocrinology, Diabetes, and Nutrition, Center for
Cardiovascular Research, Charité-University Medicine Berlin, Berlin 10115, Germany
- Division of Physiology, Department of Zoology, Faculty of Science, Beni-Suef
University, Beni Suef 62514, Egypt
| | - Biruhalem Assefa
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
- Department of Endocrinology, Diabetes, and Nutrition, Center for
Cardiovascular Research, Charité-University Medicine Berlin, Berlin 10115, Germany
| | - Martin O Weickert
- Warwickshire Institute for the Study of Diabetes, Endocrinology and
Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry CV2 2DX,
United Kingdom
- Division of Metabolic and Vascular Health, Warwick Medical School,
University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Aikatarini Adamidou
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
| | - Volker Bähr
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
| | - Jan Frystyk
- Medical Research Laboratory, Institute of Clinical Medicine, Faculty of
Health Sciences, Aarhus University, Aarhus DK-8000, Denmark
| | - Matthias Möhlig
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
| | - Joachim Spranger
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
- Department of Endocrinology, Diabetes, and Nutrition, Center for
Cardiovascular Research, Charité-University Medicine Berlin, Berlin 10115, Germany
- Department of Endocrinology, Diabetes and Nutrition, Experimental and
Clinical Research Centre, Charité-University Medicine Berlin and Max-Delbrück Centre
Berlin-Buch, Berlin 13125, Germany
| | - Stefanie Lieske
- Section of Metabolic Vascular Medicine, Medical Clinic III, and Paul
Langerhans Institute Dresden, Dresden University of Technology, Dresden 01069, Germany
| | - Andreas L Birkenfeld
- Section of Metabolic Vascular Medicine, Medical Clinic III, and Paul
Langerhans Institute Dresden, Dresden University of Technology, Dresden 01069, Germany
- Division of Diabetes and Nutritional Sciences, Faculty of Life Sciences and
Medicine, King’s College London, London SE1 8WA, United Kingdom
| | - Andreas F H Pfeiffer
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
- Department of Clinical Nutrition, German Institute of Human Nutrition
Potsdam-Rehbrücke, Nuthetal 14558, Germany
| | - Ayman M Arafat
- Department of Endocrinology, Diabetes, and Nutrition, Charité-University
Medicine Berlin, Berlin 10117, Germany
- Department of Clinical Nutrition, German Institute of Human Nutrition
Potsdam-Rehbrücke, Nuthetal 14558, Germany
- Department of Endocrinology, Diabetes, and Nutrition, Center for
Cardiovascular Research, Charité-University Medicine Berlin, Berlin 10115, Germany
- Address all correspondence and requests for reprints to: Ayman M. Arafat,
MD, Department of Endocrinology, Diabetes, and Nutrition, Charité-University Medicine
Berlin, Chariteplatz 1, Berlin 10117, Germany. E-mail:
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Thomsen J, Hjortebjerg R, Espelund U, Ørtoft G, Vestergaard P, Magnusson NE, Conover CA, Tramm T, Hager H, Høgdall C, Høgdall E, Oxvig C, Frystyk J. PAPP-A proteolytic activity enhances IGF bioactivity in ascites from women with ovarian carcinoma. Oncotarget 2016; 6:32266-78. [PMID: 26336825 PMCID: PMC4741676 DOI: 10.18632/oncotarget.5010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 08/14/2015] [Indexed: 11/25/2022] Open
Abstract
Pregnancy-associated plasma protein-A (PAPP-A) stimulates insulin-like growth factor (IGF) action through proteolysis of IGF-binding protein (IGFBP)-4. In experimental animals, PAPP-A accelerates ovarian tumor growth by this mechanism. To investigate the effect of PAPP-A in humans, we compared serum and ascites from 22 women with ovarian carcinoma. We found that ascites contained 46-fold higher PAPP-A levels as compared to serum (P < 0.001). The majority (80%) of PAPP-A was enzymatically active. This is supported by the finding that ascites contained more cleaved than intact IGFBP-4 (P < 0.03). Ascites was more potent than serum in activating the IGF-I receptor (IGF-IR) in vitro (+31%, P < 0.05); in 8 of 22 patients by more than two-fold. In contrast, ascites contained similar levels of immunoreactive IGF-I, and lower levels of IGF-II (P < 0.001). Immunohistochemistry demonstrated the presence of IGF-IR in all but one tumor, whereas all tumors expressed PAPP-A, IGFBP-4, IGF-I and IGF-II. Addition of recombinant PAPP-A to ascites increased the cleavage of IGFBP-4 and enhanced IGF-IR activation (P < 0.05). In conclusion, human ovarian tumors express PAPP-A, IGFBP-4 and IGFs and these proteins are also present in ascites. We suggest that both soluble PAPP-A in ascites and tissue-associated PAPP-A serve to increase IGF bioactivity and, thereby, to stimulate IGF-IR-mediated tumor growth.
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Affiliation(s)
- Jacob Thomsen
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Rikke Hjortebjerg
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Ulrick Espelund
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Gitte Ørtoft
- Department of Gynecology, Aarhus University Hospital, DK-8200 Aarhus N, Denmark
| | - Poul Vestergaard
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark.,Department of Endocrinology and Internal Medicine, Aarhus University Hospital, DK-8000 Aarhus C, Denmark
| | - Nils E Magnusson
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Cheryl A Conover
- Division of Endocrinology and Metabolism, Endocrine Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Trine Tramm
- Department of Pathology, Aarhus University Hospital, DK-8000 Aarhus C, Denmark
| | - Henrik Hager
- Department of Pathology, Aarhus University Hospital, DK-8000 Aarhus C, Denmark
| | - Claus Høgdall
- Clinic of Gynecology, Juliane Marie Centret, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Estrid Høgdall
- Department of Pathology, Herlev University Hospital, DK-2730 Herlev, Denmark
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, Faculty of Science & Technology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Jan Frystyk
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark.,Department of Endocrinology and Internal Medicine, Aarhus University Hospital, DK-8000 Aarhus C, Denmark
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Yuen KCJ, Frystyk J, Rhoads SA, Bidlingmaier M. Pegvisomant-primed glucagon stimulation test in assessing GH reserve and GH/IGF kinetics in adults suspected of GH deficiency. Pituitary 2016; 19:65-74. [PMID: 26496767 DOI: 10.1007/s11102-015-0688-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
PURPOSE The accuracy of the glucagon stimulation test(GST) in diagnosing adult GH deficiency (GHD) has recently been questioned. Because pegvisomant (PegV)increases endogenous GH secretion, we hypothesized that priming PegV to the GST (PegV-GST) 72 h beforehand would improve the diagnostic accuracy of this test. This pilot study aimed to prospectively compare PegV-GST to two other diagnostic tests for adult GHD. METHODS Adults suspected of GHD underwent PegVGST,GST and insulin tolerance test (ITT) in random order.Growth hormone levels (measured by a PegV insensitive assay) during PegV-GST, GST and ITT were compared,and acute effects of PegV on GH/IGF kinetics were assessed. RESULTS Ten subjects with hypothalamic-pituitary disease and 1–4 pituitary hormone deficiencies were studied. Basal and peak GH levels with the PegV-GST were comparable to those of the GST and ITT. The five subjects that failed the GST and ITT were the same subjects that failed the PegVGST,using the peak GH cut point of<3 ng/mL for this test. After PegV priming, basal GH and GH binding protein(GHBP) increased (both P<0.01) and total IGF-I and bioactive IGF decreased (both P<0.05), whereas IGF-II and IGFBPs -1, -2 and -3 were unchanged compared to pre-PegV priming. Serum PegV levels correlated positively with basal GH, peak GH, IGFBP-1 and IGFBP-2 levels, and negatively with D bioactive IGF and DGHBP (all P<0.05). CONCLUSION Single dose PegV administration in adults suspected of GHD increased basal GH and GHBP, with concomitant rapid fall in IGF-I levels and bioactive IGF. PegV priming did not appear to improve the diagnostic accuracy of the GST. Further studies involving larger subject numbers are needed to verify the clinical utility of PegV-GST in evaluating adult GHD.
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Tzschoppe A, Riedel C, von Kries R, Struwe E, Rascher W, Dörr HG, Beckmann MW, Schild RL, Goecke TW, Flyvbjerg A, Frystyk J, Dötsch J. Differential effects of low birthweight and intrauterine growth restriction on umbilical cord blood insulin-like growth factor concentrations. Clin Endocrinol (Oxf) 2015; 83:739-45. [PMID: 26118397 DOI: 10.1111/cen.12844] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/28/2015] [Accepted: 06/10/2015] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Alterations in the growth hormone-insulin-like growth factor (IGF) axis have been considered as a causal factor for intrauterine growth restriction (IUGR) and for the increased risk of metabolic disease in later life. We compared members of the IGF axis in umbilical cord blood between IUGR neonates, small for gestational age without foetal restriction (SGA) and appropriate for gestational age (AGA) neonates. DESIGN Prospective controlled multicenter study. PATIENTS Sixteen ultrasound-proven IUGR, 8 SGA and 40 AGA neonates. MEASUREMENTS Concentrations of total IGF-I and total IGF-II by immunoassays, bioactive IGF by cell-based bioassay and IGFBP-I in mixed venous and arterial umbilical cord blood samples at birth. Auxological parameters at birth. RESULTS IGF-I concentrations in IUGR [17·7 μg/l (CI 13·8;21·6)] were clearly below those in AGA [48·3 μg/l (CI 43·7;52·9)] and SGA neonates [36·0 μg/l (CI 26·6;45·4)]. IGF-II levels were significantly reduced in IUGR [201·4 μg/l (CI 190·2;212·6)] compared to AGA neonates [231·2 μg/l (CI 220·6;241·9)]. A trend for lower IGF-II concentrations was observed in IUGR when compared to SGA neonates [232·0 μg/l (CI 207·2;256·8)]. These differences could not be explained by confounding. For IGFBP-1, a trend towards higher values in IUGR was observed. CONCLUSIONS Low IGF-I cord blood concentrations in hypotrophic neonates after IUGR might not only result from low birthweight per se, but also reflect prenatal placental environment. Alterations of the IGF axis could be in the causal pathway of IUGR and thus constitute a potential surrogate marker for IUGR in the assessment of foetal programming.
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Affiliation(s)
- Anja Tzschoppe
- Department of Paediatrics and Adolescent Medicine, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Christina Riedel
- Institute of Social Paediatrics and Adolescent Medicine, University of Munich, Munich, Germany
| | - Rüdiger von Kries
- Institute of Social Paediatrics and Adolescent Medicine, University of Munich, Munich, Germany
| | - Ellen Struwe
- Regional Centre for Social Paediatrics, Klinikum Konstanz, Konstanz, Germany
| | - Wolfgang Rascher
- Department of Paediatrics and Adolescent Medicine, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Helmuth G Dörr
- Department of Paediatrics and Adolescent Medicine, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Matthias W Beckmann
- Department of Obstetrics and Gynaecology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Ralf L Schild
- Department of Obstetrics and Gynaecology, Diakonische Dienste Hannover, Hannover, Germany
| | - Tamme W Goecke
- Department of Obstetrics and Gynaecology, University of Aachen, Aachen, Germany
| | - Allan Flyvbjerg
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark
| | - Jan Frystyk
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark
| | - Jörg Dötsch
- Department of Paediatrics and Adolescent Medicine, University of Cologne, Cologne, Germany
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Sorensen JS, Birkebaek NH, Bjerre M, Pociot F, Kristensen K, Hoejberg AS, Frystyk J. Residual β-cell function and the insulin-like growth factor system in Danish children and adolescents with type 1 diabetes. J Clin Endocrinol Metab 2015; 100:1053-61. [PMID: 25532040 DOI: 10.1210/jc.2014-3521] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
CONTEXT C-peptide-positive adults with type 1 diabetes (T1D) have higher circulating total and free IGF-1 and lower IGF binding protein 1 (IGFBP-1) than C-peptide-negative patients. Whether this is also the case in children remains unknown. OBJECTIVE The objective of the study was to examine the IGF system in children/adolescents with and without residual β-cell function (RBF). DESIGN AND PATIENTS This was a cross-sectional study containing 136 prepubertal (hereof 15 RBF positive) and 206 pubertal (hereof 42 RBF positive) children/adolescents with T1D for 3-6 years as well as 40 prepubertal and 30 pubertal healthy controls. RBF was evaluated by meal-stimulated C-peptide. MAIN OUTCOME MEASURES Fasting serum levels of bioactive IGF (ie, the ability of serum to activate the IGF-1 receptor in vitro), total IGF-1, total IGF-2, and IGFBP-1 and -3. RESULTS Irrespective of pubertal status, patients with T1D showed lower bioactive IGF and total IGF-1, but higher IGFBP-1 as compared with controls (P < .05). When stratified according to RBF status, a positive RBF was associated with normalization of all IGF-related peptides but IGFBP-1 in prepubertal children (P < .05), whereas none of the IGF components were normalized in prepubertal, RBF-negative children. In pubertal children, total IGF-1 and bioactive IGF remained subnormal and IGFBP-1 supranormal, irrespective of RBF status (P < .05). CONCLUSION Independent of pubertal status, T1D was associated with an abnormal IGF system. However, a positive RBF status appeared important but only in prepubertal children, in whom all IGF components but IGFBP-1 were normalized. We speculate that the pubertal GH surge induces insulin resistance, which overrides the stimulatory effect that an RBF may exert on the liver-derived IGF system.
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Affiliation(s)
- Jesper S Sorensen
- Departments of Pediatrics (J.S.S., N.H.B., K.K.) and Endocrinology and Internal Medicine (J.F.), Aarhus University Hospital, and The Medical Research Laboratory (M.B., J.F.), Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark; Department of Pediatrics (J.S.S.), Randers Regional Hospital, DK-8930 Randers, Denmark; Department of Pediatrics E (F.P.), Herlev University Hospital, DK-2730 Herlev, Denmark; and Department of Pediatrics (A.S.H.), Aalborg University Hospital, DK-9000 Aalborg, Denmark
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12
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Yuen KCJ, Roberts CT, Frystyk J, Rooney WD, Pollaro JR, Klopfenstein BJ, Purnell JQ. Short-term, low-dose GH therapy improves insulin sensitivity without modifying cortisol metabolism and ectopic fat accumulation in adults with GH deficiency. J Clin Endocrinol Metab 2014; 99:E1862-9. [PMID: 25013996 PMCID: PMC4184063 DOI: 10.1210/jc.2014-1532] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Low-dose GH (LGH) therapy has been reported to improve insulin sensitivity in GH-deficient adults; however, the mechanism is unclear. HYPOTHESIS Effects of LGH therapy on insulin sensitivity are mediated through changes in cortisol metabolism and ectopic fat accumulation. DESIGN AND SETTING This was a double-blind, placebo-controlled, parallel, 3-month study. PARTICIPANTS AND INTERVENTION Seventeen GH-deficient adults were randomized to receive either daily LGH or placebo injections. Fasting blood samples were collected at baseline, and months 1 and 3, whereas hyperinsulinemic-euglycemic clamps, magnetic resonance spectroscopy scans, 24-hour cortisol production rates (CPRs), and sc abdominal fat biopsies were performed at baseline and month 3. MAIN OUTCOME MEASURES Clamp glucose infusion rate, intramyocellular, extramyocellular, and intrahepatic lipid content, 24-hour CPRs, adipocyte size, and adipocyte 11β-hydroxysteroid dehydrogenase activity in adults with GH deficiency were evaluated. RESULTS At month 1, LGH did not alter fasting levels of glucose, insulin, C-peptide, free fatty acid, adiponectin, total IGF-1, IGF-1 bioactivity, IGF-2, IGF binding protein (IGFBP)-2, or IGF-1 to IGFBP-3 molar ratio. At month 3, LGH increased clamp glucose infusion rates (P < .01) and IGF-1 to IGFBP-3 molar ratio (P < .05), but fasting glucose, insulin, C-peptide, free fatty acid, adiponectin, IGF-1 bioactivity, IGF-2, IGFBP-2, 24-hour CPRs, adipocyte size, adipocyte 11β-hydroxysteroid dehydrogenase activity, intrahepatic lipid, extramyocellular, or intramyocellular were unchanged. In the placebo group, all within-group parameters from months 1 and 3 compared with baseline were unchanged. CONCLUSIONS Short-term LGH therapy improves insulin sensitivity without inducing basal lipolysis and had no effect on cortisol metabolism and ectopic fat accumulation in GH-deficient adults. This may reflect an LGH-induced increase in IGF-1 to IGFBP-3 molar ratio exerting insulin-like effects through the abundant muscle IGF-1 receptors, but this hypothesis requires confirmation with further studies.
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Affiliation(s)
- Kevin C J Yuen
- Division of Endocrinology, Diabetes, and Clinical Nutrition (K.C.J.Y., C.T.R., B.J.K., J.Q.P.), Department of Medicine, and Advanced Imaging Research Center (W.D.R., J.R.P.), Oregon Health and Science University, Portland, Oregon 97239; Oregon National Primate Research Center (C.T.R.), Beaverton, Oregon 97006; and Institute of Clinical Medicine N (J.F.), Aarhus University, DK-8000 Aarhus, Denmark
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13
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Reinhard M, Frystyk J, Jespersen B, Randers E, Bjerre M, Christiansen JS, Flyvbjerg A, Bibby BM, Ivarsen P. Impaired postprandial response of the insulin-like growth factor system in maintenance haemodialysis. Clin Endocrinol (Oxf) 2014; 80:757-65. [PMID: 24138555 DOI: 10.1111/cen.12352] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 09/02/2013] [Accepted: 10/15/2013] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Patients on maintenance haemodialysis (HD) have reduced circulating free and bioactive insulin-like growth factor I (IGF-I) due to increased IGF-binding proteins (IGFBPs). This study investigated the postprandial response of the IGF system in HD patients compared with matched healthy subjects. DESIGN AND PATIENTS In a crossover study, twelve nondiabetic HD patients were assigned in a random order to three 10-h study days: (1) a non-HD day with one meal served at baseline (NHDM1), (2) an HD day with one meal served during HD (HDM1) and (3) an HD day with two meals served during and after HD, respectively (HDM2). Twelve healthy controls conducted session 1. RESULTS After the baseline meal, insulin concentrations changed similarly in HD patients and controls, whereas hyperglycaemia was more prolonged in HD patients (P < 0·001). Postprandial IGFBP-1 showed greater reductions from baseline in controls (-76% [-81; -70%], mean [95% confidence intervals], P < 0·001) than in patients on non-HD days (-45% [-57; -30%], P < 0·001). In the latter group, the response was even more attenuated during HD (-22% [-38; -1%] and -24% [-40; -4%], P ≤ 0·041). After the second meal on HDM2 days, IGFBP-1 further decreased (-50% [-61; -37%], P < 0·001), whereas IGFBP-1 returned to baseline levels on the other study days. Consistently, at the end of the study days, bioactive IGF-I was significantly above baseline only on HDM2 days (+22% [+5; +43%], P = 0·012). CONCLUSIONS HD patients were unable to suppress IGFBP-1 to the same extent as healthy controls, which may increase the risk of protein-energy wasting in maintenance HD. A second meal after HD, however, effectively suppressed IGFBP-1 and increased bioactive IGF-I.
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Affiliation(s)
- Mark Reinhard
- Department of Renal Medicine, Aarhus University Hospital, Aarhus C, Denmark; Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus C, Denmark
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Ma Z, Christiansen JS, Laursen T, Wu C, Lauritzen T, Parkner T, Frystyk J. Effects of human insulin and insulin aspart preparations on levels of IGF-I, IGFBPs and IGF bioactivity in patients with type 1 diabetes. BMC Endocr Disord 2014; 14:35. [PMID: 24725803 PMCID: PMC3986432 DOI: 10.1186/1472-6823-14-35] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 04/01/2014] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Insulin aspart (IAsp) and its biphasic preparations BIAsp50 and BIAsp70 (containing 50% and 70% IAsp, respectively) have distinct glucose-lowering properties as compared to human insulin (HI). We investigated whether this affected the circulating IGF-system which depends on the hepatic insulin exposure. METHODS In a randomized, four-period crossover study, 19 patients with type 1 diabetes received identical doses (0.2 U/kg sc) of IAsp, BIAsp70, BIAsp50 and HI together with a standardized meal. Serum total IGF-I and IGFBP-1 to -3 were measured by immunoassays for nine hours post-prandially. Bioactive IGF was determined by an in-house, cell-based IGF-I receptor kinase activation (KIRA) assay. RESULTS Despite marked differences in peripheral insulin concentrations and plasma glucose, the four insulin preparations resulted in parallel decreases in IGFBP-1 levels during the first 3 hours, and parallel increases during the last part of the study (3-9 hours). Thus, only minor significances were seen. Insulin aspart and human insulin resulted in a lower area under the curve (AUC) during the first 3 hours as compared to BIAsp70 (p = 0.009), and overall, human insulin resulted in a lower IGFBP-1 AUC than BIAsp70 (p = 0.025). Nevertheless, responses and AUCs of bioactive IGF were similar for all four insulin preparations. Changes in levels of bioactive IGF were inversely correlated to those of IGFBP-1, increasing during the first 3 hours, whereafter levels declined (-0.83 ≤ r ≤ -0.30; all p-values <0.05).Total IGF-I and IGFBP-3 remained stable during the 9 hours, whereas IGFBP-2 changed opposite of IGFBP-1, increasing after 3-4 hours whereafter levels gradually declined. The four insulin preparations resulted in similar profiles and AUCs of total IGF-I, IGFBP-2 and IGFBP-3. CONCLUSIONS Despite distinct glucose-lowering properties, the tested insulin preparations had similar effects on IGF-I concentration and IGF bioactivity, IGFBP-2 and IGFBP-3 as compared to HI; only small differences in IGFBP-1 were seen and they did not affect bioactive IGF. Thus, insulin aspart containing preparation behaves as HI in regards to the circulating IGF-system. However, bioactive IGF appeared to be more sensitive to insulin exposure than total IGF-I. The physiological significance of this finding remains to be determined. TRIAL REGISTRATION NCT00888732.
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Affiliation(s)
- Zhulin Ma
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade, DK-8000 Aarhus C, Denmark
| | - Jens Sandahl Christiansen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade, DK-8000 Aarhus C, Denmark
| | - Torben Laursen
- Department of Biomedicine - Pharmacology, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Chunsen Wu
- Department of Public Health, Section for Epidemiology, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Torsten Lauritzen
- Department of Public Health, Section of General Practice, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Tina Parkner
- Department of Clinical Biochemistry, Aarhus University Hospital, Nørrebrogade, DK-8000 Aarhus C, Denmark
| | - Jan Frystyk
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade, DK-8000 Aarhus C, Denmark
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Birzniece V, Magnusson NE, Ho KKY, Frystyk J. Effects of raloxifene and estrogen on bioactive IGF1 in GH-deficient women. Eur J Endocrinol 2014; 170:375-83. [PMID: 24347426 DOI: 10.1530/eje-13-0835] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
CONTEXT GH action is attenuated by estrogens and selective estrogen receptor modulators (SERMs) administered orally. During GH therapy in hypopituitary women, co-treatment with raloxifene, a SERM, induced a smaller gain in lean body mass (LBM) compared with estrogen, despite an equal reduction in IGF1. As a higher IGF-binding protein-3 (IGFBP3) level was observed with raloxifene co-treatment, we hypothesize that an increase in IGFBP3 reduced IGF1 bioactivity causing the attenuated anabolic effect. OBJECTIVE To assess the effects of 17β-estradiol (E₂) and raloxifene on bioactive IGF1. DESIGN In study 1, 12 GH-deficient (GHD) women were randomized to raloxifene 120 mg/day or E₂ 4 mg/day for 1 month. In study 2, 16 GHD women were randomized to 1 month GH treatment alone (0.5 mg/day) and in combination with raloxifene (60 mg/day) or E₂ (2 mg/day). We measured bioactive IGF1, immunoreactive IGF1 and IGF2, and IGFBP3 immunoreactivity and fragmentation. RESULTS Raloxifene and estrogen suppressed (P<0.05) total IGF1 equally in GHD and GH-replaced hypopituitary women. In GHD patients, neither raloxifene nor estrogen affected bioactive IGF1. GH significantly increased IGF1 bioactivity, an effect attenuated by co-treatment with raloxifene (Δ -23 ± 7%, P<0.01) and estrogen (Δ -26 ± 3%, P=0.06). Total IGF1 correlated (r(2)=0.54, P<0.001) with bioactive IGF1, which represented 3.1 ± 0.2% of the total IGF1, irrespective of the treatments. Total IGF2 was unchanged by raloxifene and estrogen treatment. IGFBP3 was significantly higher during raloxifene administration, whereas no differences in IGFBP3 fragmentation were observed. CONCLUSION Raloxifene effect on bioactive IGF1 is similar to that of estrogen despite higher IGFBP3 levels during raloxifene administration. We conclude that the observed different effects on LBM between raloxifene and estrogen treatments cannot be explained by differences in IGF1 bioactivity.
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Affiliation(s)
- Vita Birzniece
- Department of Endocrinology, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
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Vestergaard PF, Hansen M, Frystyk J, Espelund U, Christiansen JS, Jørgensen JOL, Fisker S. Serum levels of bioactive IGF1 and physiological markers of ageing in healthy adults. Eur J Endocrinol 2014; 170:229-36. [PMID: 24179101 DOI: 10.1530/eje-13-0661] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Senescent changes in body composition and muscle strength are accompanied by reduced production of GH and IGF1, but the causal relationship remains elusive. We speculate that serum bioactive IGF1, measured by the IGF1 kinase receptor activation assay, is closer related to human physiological ageing than total IGF1 measured by immunoassay. DESIGN We conducted a cross-sectional study in 150 adult males and females, between 20 and 70 years. After an overnight fasting, serum levels of bioactive IGF1, total IGF1 and IGF-binding protein 1 (IGFBP1) and IGFBP3 were assessed. Furthermore, body composition and muscle strength was measured. RESULTS Total IGF1 levels were higher in females (P=0.048). Bioactive IGF1 were identical in males and females (P=0.31), decreasing with age. Total IGF1 tended to decrease more with age compared with bioactive IGF1 (-1.48 vs -0.89 percent/year, P=0.052). Total body fat (TBF) was lower and BMI was higher in males (P<0.001 and P=0.005), and both increased with age. Knee extension and elbow flexion force were higher in males (P=0.001 and P=0.001), but decreased with age in both genders. Total but not bioactive IGF1 was positively correlated to TBF, knee extension and muscle function in males. In multiple linear regression, only age predicted total IGF1, whereas age and IGFBP1 predicted bioactive IGF1. CONCLUSIONS Bioactive IGF1 tends to decrease to a lesser extent than total IGF1 with age and was not correlated with measures of body composition or muscle strength. Therefore, levels of circulating bioactive IGF1 does not appear to be a better biomarker of physiological ageing than total IGF1.
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Affiliation(s)
- Poul Frølund Vestergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, DK-8000 Aarhus C, Denmark
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Abstract
The worldwide clinical and scientific interest in peptides belonging to the insulin-like growth factor (IGF) system has brought along a call for standardization of assays used to quantify the different IGF related proteins. This relates in particular to the measurement of IGF-I, which has stood the test of time as an important biochemical tool in the diagnosis and treatment of growth hormone (GH) related disorders. The first international consensus statement on the measurement of IGF-I in 2011 represents an important milestone and will undoubtedly improve commutability of reference ranges for IGF-I and clinically applicable cut-off values. By contrast, there is no consensus addressing the measurements of the other IGF-related peptides. Nevertheless, measurement of these peptides may be of interest, either as additional tools in GH disorders or as prognostic biomarkers of various diseases. Therefore, standardization of assays for the other IGF-related peptides is highly relevant. This chapter discusses the recent consensus on IGF-I measurements and how this approach may be applied to measurement of the other IGF-related peptides. In addition, assay pitfalls, pre- and post-analytical challenges, alternative methods for IGF-I measurements and potential assays of tomorrow will be discussed.
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Affiliation(s)
- Rikke Hjortebjerg
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, DK-8000 Aarhus C, Denmark
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Hjortebjerg R, Flyvbjerg A, Frystyk J. Insulin growth factor binding proteins as therapeutic targets in type 2 diabetes. Expert Opin Ther Targets 2013; 18:209-24. [PMID: 24261835 DOI: 10.1517/14728222.2014.858698] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
INTRODUCTION The signaling pathways of the insulin-like growth factors (IGFs) have been implicated in the aetiology of type 2 diabetes (T2D) and a number of therapeutic modalities aiming at the IGF-axis have been considered. Administration of IGF-I has been reported to improve insulin sensitivity in healthy subjects and patients with T2D. In recent years, the IGF binding proteins (IGFBPs) have also been associated with metabolic disorders, prompting the idea that IGFBPs play important roles in the pathogenesis of T2D. Thus, by virtue of their role in the regulation of IGF effects, the IGFBPs have emerged as potential biomarkers and therapeutic targets in metabolic syndromes and T2D. AREAS COVERED The article provides an overview on recent findings in clinical and experimental IGFBP-research and addresses the studies that have investigated the potentials of the IGFBPs as therapeutic targets in T2D. EXPERT OPINION There is plenty of therapeutic promise within the IGF system, but further understanding of the IGFs in T2D is necessary to avoid off-target effects. Strong evidence supports the use of IGFBPs as therapeutic targets in the treatment of T2D, and it is not difficult to foresee the use of IGFBPs as part of a combination therapy alongside other anti-diabetic drugs.
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Affiliation(s)
- Rikke Hjortebjerg
- Aarhus University, Department of Clinical Medicine, Medical Research Laboratory, Faculty of Health , DK-8000 Aarhus C , Denmark
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Reinhard M, Frystyk J, Jespersen B, Bjerre M, Christiansen JS, Flyvbjerg A, Ivarsen P. Effect of hyperinsulinemia during hemodialysis on the insulin-like growth factor system and inflammatory biomarkers: a randomized open-label crossover study. BMC Nephrol 2013; 14:80. [PMID: 23557110 PMCID: PMC3637492 DOI: 10.1186/1471-2369-14-80] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 03/27/2013] [Indexed: 12/16/2022] Open
Abstract
Background A marked reduction in serum levels of bioactive insulin-like growth factor-I (IGF-I) has been observed in fasting hemodialysis (HD) patients during a 4-h HD session. The aim of the present study was to investigate the beneficial effect of hyperinsulinemia during HD on bioactive IGF-I and inflammatory biomarkers. Methods In a randomized cross-over study, 11 non-diabetic HD patients received a standardised HD session with either: 1) no treatment, 2) glucose infusion (10% glucose, 2.5 mL/kg/h), or 3) glucose-insulin infusion (10% glucose added 30 IU NovoRapid® per litre, 2.5 mL/kg/h). Each experiment consisted of three periods: pre-HD (−120 to 0 min), HD (0 to 240 min), and post-HD (240 to 360 min). A meal was served at baseline (−120 min); infusions were administered from baseline to 240 min. The primary outcome was change in bioactive IGF-I during the experiment. Secondary outcomes were changes in high-sensitivity C-reactive protein, interleukin-1β, interleukin-6, and tumor necrosis factor α. Comparisons were performed using mixed-model analysis of variance for repeated measures. Results From baseline to the end of study, no significant differences were observed in the changes in either serum bioactive IGF-I or total IGF-I between study days. Overall, serum bioactive IGF-I levels rose above baseline at 120 to 300 min with a maximum increase of 20% at 120 min (95% confidence interval (CI), 9 to 31%; p < 0.001), whereas total IGF-I levels rose above baseline at 180 to 300 min with a maximum increase of 5% at 240 min (95% CI, 2 to 9%; p = 0.004). A significant difference was observed in the changes in serum IGF-binding protein-1 (IGFBP-1) between study days (p = 0.008), but differences were only significant in the post-HD period. From baseline to the end of HD, no significant difference was observed in the changes in serum IGFBP-1 levels between study days, and in this time period overall serum IGFBP-1 levels were below baseline at all time points with a maximum decrease of 51% at 180 min (95% CI, 45 to 57%; p < 0.001). None of the investigated inflammatory biomarkers showed any differences in the changes over time between study days. Conclusions Postprandial insulin secretion stimulated the IGF-system during HD with no further effect of adding glucose or glucose-insulin infusion. Hyperinsulinemia during HD had no effect on biomarkers of inflammation. Trial registration ClinicalTrials.gov registry: NCT01209403
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Frystyk J, Schou AJ, Heuck C, Vorum H, Lyngholm M, Flyvbjerg A, Wolthers OD. Prednisolone reduces the ability of serum to activate the IGF1 receptor in vitro without affecting circulating total or free IGF1. Eur J Endocrinol 2013; 168:1-8. [PMID: 23038624 DOI: 10.1530/eje-12-0518] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE End-point bioassays based on thymidine or sulfate incorporation have demonstrated that glucocorticoid (GC) treatment inhibits serum IGF1 action, but the mechanism is unknown as serum IGF1 concentrations have been reported to either increase or remain unchanged. AIM To investigate whether GC treatment affects the ability of serum to activate the IGF1 receptor (IGF1R) in vitro (i.e. bioactive IGF1), using a specific cell-based IGF1 kinase receptor activation assay. SUBJECTS AND METHODS Twenty children with stable asthma (age 7.7-13.8 years) treated for 1 week with 5 mg prednisolone in a randomized, double-blind, placebo-controlled crossover study. Non-fasting serum samples were collected in the afternoon after each 7-day period and assayed for bioactive IGF1, free IGF1, total IGFs, IGF-binding proteins (IGFBPs), and insulin. RESULTS Prednisolone treatment reduced IGF1 bioactivity by 12.6% from 2.22±0.18 to 1.94±0.15 μg/l (P=0.01) compared with placebo. In contrast, no changes were observed for (μg/l; placebo vs prednisolone) total IGF1 (215±27 vs 212±24), free IGF1 (1.50±0.16 vs 1.43±0.17), total IGF2 (815±26 vs 800±31), IGFBP3 (3140±101 vs 3107±95), IGFBP2 (238±21 vs 220±19), IGFBP1 (32±6 vs 42±10), or IGFBP1-bound IGF1 (24±5 vs 26±7). Insulin remained unchanged as did IGFBP levels as estimated by western ligand blotting. Prednisolone had no direct effects on IGF1R phosphorylation. CONCLUSIONS Our study gives evidence that GC treatment induces a circulating substance that is able to inhibit IGF1R activation in vitro without affecting circulating free or total IGF1. This may be one of the mechanisms by which GC inhibits IGF1 action in vivo. However, the nature of this circulating substance remains to be identified.
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Affiliation(s)
- Jan Frystyk
- Institute of Clinical Medicine, Aarhus University, Aarhus C, Denmark.
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Espelund U, Søndergaard K, Bjerring P, Flyvbjerg A, Frystyk J. Interstitial fluid contains higher in vitro IGF bioactivity than serum: a study utilizing the suction blister technique. Growth Horm IGF Res 2012; 22:234-239. [PMID: 22939216 DOI: 10.1016/j.ghir.2012.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 08/06/2012] [Accepted: 08/06/2012] [Indexed: 11/25/2022]
Abstract
CONTEXT Circulating insulin-like growth factors (IGFs) are bound in complexes which affect their tissue-accessibility. Interstitial fluid is in close proximity to target cells, but the IGF-system is not well-described herein. OBJECTIVE To perform a thorough comparison of the IGF-system in suction blister fluid (SBF) vs. in serum, with emphasis on bioactive IGF levels. DESIGN Eight hour study including samples collected in the fasting state (20 h) and after a meal. SETTING Clinical research facility. PARTICIPANTS Six healthy males (age 37.0±8.8 years, BMI 22.5±1.4 kg/m(2)) (mean±SD). MAIN OUTCOME MEASURE Serum and SBF concentrations of bioactive IGF (determined in vitro by specific IGF-I receptor (IGF-IR) phosphorylation assay), immunoreactive IGF and IGF binding protein (IGFBP) levels, Western ligand blotting (WLB) of IGFBPs and IGFBP-3 Western immunoblotting (WiB). RESULTS The ability of SBF to phosphorylate the IGF-IR in vitro was 41±27% higher than that of serum (P=0.007 by repeated measures ANOVA). By contrast, immunoreactive IGF and IGFBP-concentrations were approximately 50% lower in SBF than in serum (all P≤0.002). A marked difference in the composition of IGFBPs between serum and SBF was observed, including 3-fold elevated amounts of IGFBP-3 fragments in SBF (P<0.001). For both IGF-I, IGF-II and IGFBP-2, the effect of food intake differed between serum and SBF (all P≤0.03). CONCLUSION Despite lower concentrations, the in vitro IGF bioactivity was higher in SBF than in serum. This may relate to an increased enzymatic IGFBP-degradation and an altered IGFBP-composition in SBF, making more IGF-I and -II accessible to the IGF-IR. The impact of food intake on the IGF system differs between serum and interstitial fluid.
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Affiliation(s)
- Ulrick Espelund
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Denmark.
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