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Yunn NO, Kim J, Ryu SH, Cho Y. A stepwise activation model for the insulin receptor. Exp Mol Med 2023; 55:2147-2161. [PMID: 37779149 PMCID: PMC10618199 DOI: 10.1038/s12276-023-01101-1] [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: 04/28/2023] [Revised: 06/25/2023] [Accepted: 07/24/2023] [Indexed: 10/03/2023] Open
Abstract
The binding of insulin to the insulin receptor (IR) triggers a cascade of receptor conformational changes and autophosphorylation, leading to the activation of metabolic and mitogenic pathways. Recent advances in the structural and functional analyses of IR have revealed the conformations of the extracellular domains of the IR in inactive and fully activated states. However, the early activation mechanisms of this receptor remain poorly understood. The structures of partially activated IR in complex with aptamers provide clues for understanding the initial activation mechanism. In this review, we discuss the structural and functional features of IR complexed with various ligands and propose a model to explain the sequential activation mechanism. Moreover, we discuss the structures of IR complexed with biased agonists that selectively activate metabolic pathways and provide insights into the design of selective agonists and their clinical implications.
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Affiliation(s)
- Na-Oh Yunn
- Postech Biotech Center, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
| | - Junhong Kim
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Sung Ho Ryu
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Yunje Cho
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
- Department of Biomedical Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
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2
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Ong SC, Belgi A, Merriman AL, Delaine CA, van Lierop B, Andrikopoulos S, Robinson AJ, Forbes BE. Minimizing Mitogenic Potency of Insulin Analogues Through Modification of a Disulfide Bond. Front Endocrinol (Lausanne) 2022; 13:907864. [PMID: 35832429 PMCID: PMC9271792 DOI: 10.3389/fendo.2022.907864] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 05/09/2022] [Indexed: 11/13/2022] Open
Abstract
The mechanisms by which insulin activates the insulin receptor to promote metabolic processes and cellular growth are still not clear. Significant advances have been gained from recent structural studies in understanding how insulin binds to its receptor. However, the way in which specific interactions lead to either metabolic or mitogenic signalling remains unknown. Currently there are only a few examples of insulin receptor agonists that have biased signalling properties. Here we use novel insulin analogues that differ only in the chemical composition at the A6-A11 bond, as it has been changed to a rigid, non-reducible C=C linkage (dicarba bond), to reveal mechanisms underlying signaling bias. We show that introduction of an A6-A11 cis-dicarba bond into either native insulin or the basal/long acting insulin glargine results in biased signalling analogues with low mitogenic potency. This can be attributed to reduced insulin receptor activation that prevents effective receptor internalization and mitogenic signalling. Insight gained into the receptor interactions affected by insertion of an A6-A11 cis-dicarba bond will ultimately assist in the development of new insulin analogues for the treatment of diabetes that confer low mitogenic activity and therefore pose minimal risk of promoting cancer with long term use.
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Affiliation(s)
- Shee Chee Ong
- Discipline of Medical Biochemistry, Flinders Health and Medical Research Institute, Flinders University of South Australia, Bedford Park, SA, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, VIC, Australia
| | - Allanah L. Merriman
- Discipline of Medical Biochemistry, Flinders Health and Medical Research Institute, Flinders University of South Australia, Bedford Park, SA, Australia
| | - Carlie A. Delaine
- Discipline of Medical Biochemistry, Flinders Health and Medical Research Institute, Flinders University of South Australia, Bedford Park, SA, Australia
| | | | | | | | - Briony E. Forbes
- Discipline of Medical Biochemistry, Flinders Health and Medical Research Institute, Flinders University of South Australia, Bedford Park, SA, Australia
- *Correspondence: Briony E. Forbes,
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3
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Tseng CH. The Relationship between Diabetes Mellitus and Gastric Cancer and the Potential Benefits of Metformin: An Extensive Review of the Literature. Biomolecules 2021; 11:biom11071022. [PMID: 34356646 PMCID: PMC8301937 DOI: 10.3390/biom11071022] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/02/2021] [Accepted: 07/08/2021] [Indexed: 12/14/2022] Open
Abstract
The objective of this review is to summarize the findings of published research that investigated the relationship between diabetes mellitus and gastric cancer (GCa) and the potential benefits of metformin on GCa. Related literature has been extensively reviewed, and findings from studies investigating the relationship between diabetes mellitus and GCa suggest that hyperglycemia, hyperinsulinemia and insulin resistance are closely related to the development of GCa. Although not supported by all, most observational studies suggest an increased risk of GCa in patients with type 2 diabetes mellitus, especially in women and in Asian populations. Incidence of second primary malignancy diagnosed after GCa is significantly higher in diabetes patients. Diabetes patients with GCa may have more complications after gastrectomy or chemotherapy and they may have a poorer prognosis than patients with GCa but without diabetes mellitus. However, glycemic control may improve in the diabetes patients with GCa after receiving gastrectomy, especially after procedures that bypass the duodenum and proximal jejunum, such as Roux-en-Y gastric bypass or Billroth II reconstruction. The potential links between diabetes mellitus and GCa may involve the interactions with shared risk factors (e.g., obesity, hyperglycemia, hyperinsulinemia, insulin resistance, high salt intake, smoking, etc.), Helicobacter pylori (HP) infection, medications (e.g., insulin, metformin, statins, aspirin, proton pump inhibitors, antibiotics, etc.) and comorbidities (e.g., hypertension, dyslipidemia, vascular complications, heart failure, renal failure, etc.). With regards to the potential benefits of metformin on GCa, results of most observational studies suggest a reduced risk of GCa associated with metformin use in patients with T2DM, which can be supported by evidence derived from many in vitro and animal studies. Metformin use may also reduce the risk of HP infection, an important risk factor of GCa. In patients with GCa, metformin users may have improved survival and reduced recurrence. More studies are required to clarify the pathological subtypes/anatomical sites of GCa associated with type 2 diabetes mellitus or prevented by metformin, to confirm whether GCa risk can also be increased in patients with type 1 diabetes mellitus and to explore the possible role of gastric microbiota in the development of GCa.
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Affiliation(s)
- Chin-Hsiao Tseng
- Department of Internal Medicine, National Taiwan University College of Medicine, Taipei 10051, Taiwan; ; Tel.: +886-2-2388-3578
- Division of Endocrinology and Metabolism, Department of Internal Medicine, National Taiwan University Hospital, Taipei 10051, Taiwan
- Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Zhunan 350, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, No. 7 Chung-Shan South Road, Taipei 100, Taiwan
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4
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Biondo LA, Teixeira AAS, de O. S. Ferreira KC, Neto JCR. Pharmacological Strategies for Insulin Sensitivity in Obesity and Cancer: Thiazolidinediones and Metformin. Curr Pharm Des 2020; 26:932-945. [DOI: 10.2174/1381612826666200122124116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 12/21/2019] [Indexed: 12/19/2022]
Abstract
Background:
Chronic diseases, such as obesity and cancer, have high prevalence rates. Both diseases
have hyperinsulinemia, hyperglycemia, high levels of IGF-1 and inflammatory cytokines in common. Therefore,
these can be considered triggers for cancer development and growth. In addition, low-grade inflammation that
modulates the activation of immune cells, cellular metabolism, and production of cytokines and chemokines are
common in obesity, cancer, and insulin resistance. Pharmacological strategies are necessary when a change in
lifestyle does not improve glycemic homeostasis. In this regard, thiazolidinediones (TZD) possess multiple molecular
targets and regulate PPARγ in obesity and cancer related to insulin resistance, while metformin acts
through the AMPK pathway.
Objective:
The aim of this study was to review TZD and metformin as pharmacological treatments for insulin
resistance associated with obesity and cancer.
Conclusions:
Thiazolidinediones restored adiponectin secretion and leptin sensitivity, reduced lipid droplets in
hepatocytes and orexigen peptides in the hypothalamus. In cancer cells, TZD reduced proliferation, production of
reactive oxygen species, and inflammation by acting through the mTOR and NFκB pathways. Metformin has
similar effects, though these are AMPK-dependent. In addition, both drugs can be efficient against certain side
effects caused by chemotherapy.
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Affiliation(s)
- Luana A. Biondo
- Immunometabolism Research Group, Department of Cell Biology and Development, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Alexandre A. S. Teixeira
- Immunometabolism Research Group, Department of Cell Biology and Development, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Karen C. de O. S. Ferreira
- Immunometabolism Research Group, Department of Cell Biology and Development, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Jose C. R. Neto
- Immunometabolism Research Group, Department of Cell Biology and Development, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
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Yunn NO, Kim J, Kim Y, Leibiger I, Berggren PO, Ryu SH. Mechanistic understanding of insulin receptor modulation: Implications for the development of anti-diabetic drugs. Pharmacol Ther 2018; 185:86-98. [DOI: 10.1016/j.pharmthera.2017.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Belfiore A, Malaguarnera R, Vella V, Lawrence MC, Sciacca L, Frasca F, Morrione A, Vigneri R. Insulin Receptor Isoforms in Physiology and Disease: An Updated View. Endocr Rev 2017; 38:379-431. [PMID: 28973479 PMCID: PMC5629070 DOI: 10.1210/er.2017-00073] [Citation(s) in RCA: 234] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/13/2017] [Indexed: 02/08/2023]
Abstract
The insulin receptor (IR) gene undergoes differential splicing that generates two IR isoforms, IR-A and IR-B. The physiological roles of IR isoforms are incompletely understood and appear to be determined by their different binding affinities for insulin-like growth factors (IGFs), particularly for IGF-2. Predominant roles of IR-A in prenatal growth and development and of IR-B in metabolic regulation are well established. However, emerging evidence indicates that the differential expression of IR isoforms may also help explain the diversification of insulin and IGF signaling and actions in various organs and tissues by involving not only different ligand-binding affinities but also different membrane partitioning and trafficking and possibly different abilities to interact with a variety of molecular partners. Of note, dysregulation of the IR-A/IR-B ratio is associated with insulin resistance, aging, and increased proliferative activity of normal and neoplastic tissues and appears to sustain detrimental effects. This review discusses novel information that has generated remarkable progress in our understanding of the physiology of IR isoforms and their role in disease. We also focus on novel IR ligands and modulators that should now be considered as an important strategy for better and safer treatment of diabetes and cancer and possibly other IR-related diseases.
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Affiliation(s)
- Antonino Belfiore
- Endocrinology, Department of Health Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Roberta Malaguarnera
- Endocrinology, Department of Health Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Veronica Vella
- School of Human and Social Sciences, University Kore of Enna, via della Cooperazione, 94100 Enna, Italy
| | - Michael C. Lawrence
- Structural Biology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Laura Sciacca
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
| | - Francesco Frasca
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
| | - Andrea Morrione
- Department of Urology and Biology of Prostate Cancer Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Riccardo Vigneri
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
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Zhang D, Fei Q, Li J, Zhang C, Sun Y, Zhu C, Wang F, Sun Y. 2-Deoxyglucose Reverses the Promoting Effect of Insulin on Colorectal Cancer Cells In Vitro. PLoS One 2016; 11:e0151115. [PMID: 26939025 PMCID: PMC4777557 DOI: 10.1371/journal.pone.0151115] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 02/22/2016] [Indexed: 12/20/2022] Open
Abstract
An increased risk of colorectal cancer is related to the development of metabolic syndromes including hyperglycemia, and hyperinsulinemia. The high circulatory levels of glucose and/or insulin or the application of exogenous insulin may promote carcinogenesis, cancer progression and metastasis, which can be attributed to the Warburg effect or aerobic glycolysis. We attempted to resolve these existing questions by applying the glucose analog 2-deoxyglucose (2DG). According to the in vitro studies we performed, the glycolysis of colorectal cancer cells could be interrupted by 2DG as it decreased the cellular productions of ATP and lactate. In addition, 2DG induced apoptosis and cell cycle arrest, and inhibited proliferation, migration and invasion of these cells. Since insulin can stimulate the cellular uptake of hexose, including 2DG, the combination of 2DG and insulin improved the cytotoxicity of 2DG and meanwhile overcame the cancer-promoting effects of insulin. This in vitro study provided a viewpoint of 2DG as a potential therapeutic agent against colorectal cancer, especially for patients with concomitant hyperinsulinemia or treated with exogenous insulin.
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Affiliation(s)
- Dongsheng Zhang
- Department of Colorectal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Qiang Fei
- Department of Colorectal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
- The First School of Clinical Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Juan Li
- Department of Colorectal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
- The First School of Clinical Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Chuan Zhang
- Department of Colorectal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
- The First School of Clinical Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Ye Sun
- Department of Colorectal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
- The First School of Clinical Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Chunyan Zhu
- Department of Colorectal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
- The First School of Clinical Medicine, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Fengzhen Wang
- Department of Pharmaceutics, China Pharmaceutical University, Nanjing, Jiangsu, China
| | - Yueming Sun
- Department of Colorectal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
- * E-mail:
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Villadolid J, Ersek JL, Fong MK, Sirianno L, Story ES. Management of hyperglycemia from epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) targeting T790M-mediated resistance. Transl Lung Cancer Res 2015; 4:576-83. [PMID: 26629426 DOI: 10.3978/j.issn.2218-6751.2015.10.01] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) patients are associated with sensitivity to small molecule tyrosine kinase inhibitors (TKIs) such as erlotinib, gefitinib, and afatinib. Although studies show an increased progression free survival (PFS) with use of EGFR TKIs in the first-line setting, most patients will develop resistance to therapy after the first 8-16 months. T790M is an acquired resistance mutation reported in 60-70% of patients who initially responded to a prior EGFR TKI. Recently, EGFR TKIs targeting T790M have been developed to overcome resistance with positive results in PFS and objective response rate in patients who have had disease progression on at least one TKI. Two EGFR TKIs targeting T790M, AZD9291 and rociletinib, are new active treatment options for NSCLC but differ in adverse effect profiles. Dose-limiting hyperglycemia has been reported with rociletinib and has required dose reduction, an oral antihyperglycemic, or both, without discontinuation of therapy. This suggests that patients may be effectively treated chronically for hyperglycemia associated with EGFR TKIs targeting T790M, however, guidelines for treatment of hyperglycemia in this setting have not been published. We discuss mechanisms of hyperglycemia associated with TKIs and initial management of hyperglycemia, including benefits and limitations of oral antihyperglycemic options, adjustment of therapy based on grade of hyperglycemia, and recommendations for follow-up glucose monitoring.
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Affiliation(s)
- Jeryl Villadolid
- 1 Department of Pharmacy, 2 Department of Solid Tumor Oncology and Investigational Therapeutics, 3 Department of Solid Tumor Oncology, 4 Endocrine Center, Levine Cancer Institute, Carolinas HealthCare System, Charlotte, NC 28204, USA
| | - Jennifer L Ersek
- 1 Department of Pharmacy, 2 Department of Solid Tumor Oncology and Investigational Therapeutics, 3 Department of Solid Tumor Oncology, 4 Endocrine Center, Levine Cancer Institute, Carolinas HealthCare System, Charlotte, NC 28204, USA
| | - Mei Ka Fong
- 1 Department of Pharmacy, 2 Department of Solid Tumor Oncology and Investigational Therapeutics, 3 Department of Solid Tumor Oncology, 4 Endocrine Center, Levine Cancer Institute, Carolinas HealthCare System, Charlotte, NC 28204, USA
| | - Lindsey Sirianno
- 1 Department of Pharmacy, 2 Department of Solid Tumor Oncology and Investigational Therapeutics, 3 Department of Solid Tumor Oncology, 4 Endocrine Center, Levine Cancer Institute, Carolinas HealthCare System, Charlotte, NC 28204, USA
| | - Ellen S Story
- 1 Department of Pharmacy, 2 Department of Solid Tumor Oncology and Investigational Therapeutics, 3 Department of Solid Tumor Oncology, 4 Endocrine Center, Levine Cancer Institute, Carolinas HealthCare System, Charlotte, NC 28204, USA
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9
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Bedinger DH, Adams SH. Metabolic, anabolic, and mitogenic insulin responses: A tissue-specific perspective for insulin receptor activators. Mol Cell Endocrinol 2015; 415:143-56. [PMID: 26277398 DOI: 10.1016/j.mce.2015.08.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/05/2015] [Accepted: 08/09/2015] [Indexed: 12/17/2022]
Abstract
Insulin acts as the major regulator of the fasting-to-fed metabolic transition by altering substrate metabolism, promoting energy storage, and helping activate protein synthesis. In addition to its glucoregulatory and other metabolic properties, insulin can also act as a growth factor. The metabolic and mitogenic responses to insulin are regulated by divergent post-receptor signaling mechanisms downstream from the activated insulin receptor (IR). However, the anabolic and growth-promoting properties of insulin require tissue-specific inter-relationships between the two pathways, and the nature and scope of insulin-regulated processes vary greatly across tissues. Understanding the nuances of this interplay between metabolic and growth-regulating properties of insulin would have important implications for development of novel insulin and IR modulator therapies that stimulate insulin receptor activation in both pathway- and tissue-specific manners. This review will provide a unique perspective focusing on the roles of "metabolic" and "mitogenic" actions of insulin signaling in various tissues, and how these networks should be considered when evaluating selective pharmacologic approaches to prevent or treat metabolic disease.
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Affiliation(s)
| | - Sean H Adams
- Arkansas Children's Nutrition Center and University of Arkansas for Medical Sciences, Department of Pediatrics, Little Rock, AR, USA
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Janssen JAMJL, Varewijck AJ. IGF-IR Targeted Therapy: Past, Present and Future. Front Endocrinol (Lausanne) 2014; 5:224. [PMID: 25566194 PMCID: PMC4275034 DOI: 10.3389/fendo.2014.00224] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/08/2014] [Indexed: 01/01/2023] Open
Abstract
The IGF-I receptor (IGF-IR) has been studied as an anti-cancer target. However, monotherapy trials with IGF-IR targeted antibodies or with IGF-IR specific tyrosine kinase inhibitors have, overall, been very disappointing in the clinical setting. This review discusses potential reasons why IGF-I R targeted therapy fails to inhibit growth of human cancers. It has become clear that intracellular signaling pathways are highly interconnected and complex instead of being linear and simple. One of the most potent candidates for failure of IGF-IR targeted therapy is the insulin receptor isoform A (IR-A). Activation of the IR-A by insulin-like growth factor-II (IGF-II) bypasses the IGF-IR and its inhibition. Another factor may be that anti-cancer treatment may reduce IGF-IR expression. IGF-IR blocking drugs may also induce hyperglycemia and hyperinsulinemia, which may further stimulate cell growth. In addition, circulating IGF-IRs may reduce therapeutic effects of IGF-IR targeted therapy. Nevertheless, it is still possible that the IGF-IR may be a useful adjuvant or secondary target for the treatment of human cancers. Development of functional inhibitors that affect the IGF-IR and IR-A may be necessary to overcome resistance and to make IGF-IR targeted therapy successful. Drugs that modify alternative downstream effects of the IGF-IR, so called "biasing agonists," should also be considered.
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Affiliation(s)
- Joseph A. M. J. L. Janssen
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, Rotterdam, Netherlands
- *Correspondence: Joseph A. M. J. L. Janssen, Department of Internal Medicine, Erasmus MC, Room D-443, ‘s-Gravendijkwal 230, Rotterdam 3015 CE, Netherlands e-mail:
| | - Aimee J. Varewijck
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, Rotterdam, Netherlands
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