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Karl K, Paul MD, Pasquale EB, Hristova K. Ligand bias in receptor tyrosine kinase signaling. J Biol Chem 2020; 295:18494-18507. [PMID: 33122191 PMCID: PMC7939482 DOI: 10.1074/jbc.rev120.015190] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 10/28/2020] [Indexed: 12/14/2022] Open
Abstract
Ligand bias is the ability of ligands to differentially activate certain receptor signaling responses compared with others. It reflects differences in the responses of a receptor to specific ligands and has implications for the development of highly specific therapeutics. Whereas ligand bias has been studied primarily for G protein-coupled receptors (GPCRs), there are also reports of ligand bias for receptor tyrosine kinases (RTKs). However, the understanding of RTK ligand bias is lagging behind the knowledge of GPCR ligand bias. In this review, we highlight how protocols that were developed to study GPCR signaling can be used to identify and quantify RTK ligand bias. We also introduce an operational model that can provide insights into the biophysical basis of RTK activation and ligand bias. Finally, we discuss possible mechanisms underpinning RTK ligand bias. Thus, this review serves as a primer for researchers interested in investigating ligand bias in RTK signaling.
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Affiliation(s)
- Kelly Karl
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Michael D Paul
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Elena B Pasquale
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA.
| | - Kalina Hristova
- Department of Materials Science and Engineering, Institute for NanoBioTechnology, and Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland, USA.
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Jensen VFH, Brinck PR, Nowak J, Thorup I, Sjögren I, Mølck AM. Evaluation of Cell Proliferation in Rat Mammary Glands Is Not Predictive of the Carcinogenic Potential of Insulin In Vivo. Int J Toxicol 2020; 39:560-576. [PMID: 32723118 DOI: 10.1177/1091581820941776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
For nonclinical safety-assessment of insulin analogues in vivo, mitogenic effects are compared to that of human insulin. Besides histopathologic evaluation, this usually includes assessment of cell proliferation (CP) in mammary glands. Insulin analogue X10 is recommended as positive control, due to its known carcinogenic effect in rat mammary glands. Here, we discuss the mitogenic effect of insulin in vivo and use of X10 as positive control. We present results from 4 nonclinical rat studies evaluating effects of repeated dosing with insulin detemir (≤26 weeks) or degludec (52 weeks) in mammary glands. Studies included human insulin-dosed groups as comparators, CP, and histopathologic evaluation. One study included an X10-dosed group (26 weeks), another ≤3 weeks of dosing with X10 or human insulin evaluating effects of these comparators. Neither human insulin, insulin detemir, degludec, nor X10 induced mammary tumors or increased CP in the studies. The CP marker proliferating cell nuclear antigen varied within/between studies and was not correlated with the remaining markers or CP fluctuations during estrous cycle, whereas the other CP markers, Ki-67 and 5-bromo-2'-deoxyuridine (BrdU), correlated with estrous cycle changes and each other. In conclusion, we propose that the mitogenic effect of insulin in rat mammary glands is weak in vivo. Cell proliferation evaluation in nonclinical safety assessment studies is not predictive of the carcinogenic potential of insulin, thus, the value of including this end point is debatable. Moreover, X10 is not recommended as positive control, due to lack of proliferative effects. Typical CP markers vary greatly in quality, BrdU seemingly most reliable.
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Affiliation(s)
| | - Peter R Brinck
- Department of Safety Sciences & Imaging, 1450Novo Nordisk A/S, Maaloev, Denmark
| | - Jette Nowak
- Department of Safety Sciences & Imaging, 1450Novo Nordisk A/S, Maaloev, Denmark
| | - Inger Thorup
- Department of Safety Sciences & Imaging, 1450Novo Nordisk A/S, Maaloev, Denmark
| | - Ingrid Sjögren
- Department of Safety Sciences & Imaging, 1450Novo Nordisk A/S, Maaloev, Denmark
| | - Anne-Marie Mølck
- Department of Safety Sciences & Imaging, 1450Novo Nordisk A/S, Maaloev, Denmark
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3
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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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Bronsveld HK, ter Braak B, Karlstad Ø, Vestergaard P, Starup-Linde J, Bazelier MT, De Bruin ML, de Boer A, Siezen CLE, van de Water B, van der Laan JW, Schmidt MK. Treatment with insulin (analogues) and breast cancer risk in diabetics; a systematic review and meta-analysis of in vitro, animal and human evidence. Breast Cancer Res 2015; 17:100. [PMID: 26242987 PMCID: PMC4531810 DOI: 10.1186/s13058-015-0611-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 07/07/2015] [Indexed: 12/29/2022] Open
Abstract
INTRODUCTION Several studies have suggested that anti-diabetic insulin analogue treatment might increase cancer risk. The aim of this study was to review the postulated association between insulin and insulin analogue treatment and breast cancer development, and plausible mechanisms. METHOD A systematic literature search was performed on breast cell-line, animal and human studies using the key words 'insulin analogue' and 'breast neoplasia' in MEDLINE at PubMed, EMBASE, and ISI Web of Science databases. A quantitative and qualitative review was performed on the epidemiological data; due to a limited number of reported estimates, a meta-analysis was performed for glargine only. A comprehensive overview was composed for in vitro and animal studies. Protein and gene expression was analysed for the cell lines most frequently used in the included in vitro studies. RESULTS In total 16 in vitro, 5 animal, 2 in vivo human and 29 epidemiological papers were included. Insulin AspB10 showed mitogenic properties in vitro and in animal studies. Glargine was the only clinically available insulin analogue for which an increased proliferative potential was found in breast cancer cell lines. However, the pooled analysis of 13 epidemiological studies did not show evidence for an association between insulin glargine treatment and an increased breast cancer risk (HR 1.04; 95 % CI 0.91-1.17; p=0.49) versus no glargine in patients with diabetes mellitus. It has to be taken into account that the number of animal studies was limited, and epidemiological studies were underpowered and suffered from methodological limitations. CONCLUSION There is no compelling evidence that any clinically available insulin analogue (Aspart, Determir, Glargine, Glulisine or Lispro), nor human insulin increases breast cancer risk. Overall, the data suggests that insulin treatment is not involved in breast tumour initiation, but might induce breast tumour progression by up regulating mitogenic signalling pathways.
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Affiliation(s)
- Heleen K Bronsveld
- Division of Molecular Pathology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
- Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands.
| | - Bas ter Braak
- Division of Toxicology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands.
| | - Øystein Karlstad
- Department of Pharmacoepidemiology, Norwegian Institute of Public Health, Oslo, Norway.
| | - Peter Vestergaard
- Departments of Clinical Medicine and Endocrinology, Aalborg University, Aalborg, Denmark.
| | - Jakob Starup-Linde
- Departments of Clinical Medicine and Endocrinology, Aalborg University, Aalborg, Denmark.
- Department of Endocrinology and Internal Medicine (MEA), Aarhus University Hospital THG, Aarhus, Denmark.
| | - Marloes T Bazelier
- Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands.
| | - Marie L De Bruin
- Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands.
| | - Anthonius de Boer
- Division of Pharmacoepidemiology & Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Netherlands.
| | | | - Bob van de Water
- Division of Toxicology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands.
| | - Jan Willem van der Laan
- Division of Toxicology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands.
- Medicines Evaluation Board (MEB), Utrecht, The Netherlands.
- Centre for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
| | - Marjanka K Schmidt
- Division of Molecular Pathology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
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Lundby A, Bolvig P, Hegelund AC, Hansen BF, Worm J, Lützen A, Billestrup N, Bonnesen C, Oleksiewicz MB. Surface-expressed insulin receptors as well as IGF-I receptors both contribute to the mitogenic effects of human insulin and its analogues. J Appl Toxicol 2014; 35:842-50. [DOI: 10.1002/jat.3082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 09/13/2014] [Accepted: 09/15/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Anders Lundby
- Department of Biomedical Sciences; University of Copenhagen; Blegdamsvej 3 2200 Copenhagen N Denmark
| | - Pernille Bolvig
- Diabetes Research Unit, Novo Nordisk A/S; Novo Nordisk Park 2760 Maaloev Denmark
| | | | - Bo F. Hansen
- Diabetes Research Unit, Novo Nordisk A/S; Novo Nordisk Park 2760 Maaloev Denmark
| | - Jesper Worm
- Diabetes Research Unit, Novo Nordisk A/S; Novo Nordisk Park 2760 Maaloev Denmark
| | - Anne Lützen
- Diabetes Research Unit, Novo Nordisk A/S; Novo Nordisk Park 2760 Maaloev Denmark
| | - Nils Billestrup
- Department of Biomedical Sciences; University of Copenhagen; Blegdamsvej 3 2200 Copenhagen N Denmark
| | - Christine Bonnesen
- Diabetes Research Unit, Novo Nordisk A/S; Novo Nordisk Park 2760 Maaloev Denmark
| | - Martin B. Oleksiewicz
- Centre for Biosecurity and Biopreparedness; Statens Serum Institute; Artillerivej 5 2300 Copenhagen S Denmark
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Down-regulation of cyclin G2 by insulin, IGF-I (insulin-like growth factor 1) and X10 (AspB10 insulin): role in mitogenesis. Biochem J 2014; 457:69-77. [PMID: 24059861 DOI: 10.1042/bj20130490] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The mechanisms whereby insulin analogues may cause enhanced mitogenicity through activation of either the IR (insulin receptor) or the IGF-IR (insulin-like growth factor 1 receptor) are incompletely understood. We demonstrate that in L6 myoblasts expressing only IGF-IRs as well as in the same cells overexpressing the IR, IGF-I (insulin-like growth factor 1), insulin and X10 (AspB10 insulin) down-regulate the mRNA expression level of the cell cycle inhibitor cyclin G2, as measured by qRT-PCR (quantitative reverse transcription-PCR), and induce cell growth measured by [6-(3)H]thymidine incorporation into DNA. Western blotting showed a marked down-regulation of cyclin G2 at the protein level in both cell lines. Overexpression of cyclin G2 in the two cell lines diminished the mitogenic effect of all three ligands. The use of specific inhibitors indicated that both the MAPK (mitogen-activated protein kinase) and the PI3K (phosphoinositide 3-kinase) pathways mediate the down-regulation of Ccng2. The down-regulation of CCNG2 by the three ligands was also observed in other cell lines: MCF-7, HMEC, Saos-2, R(-)/IR and INS-1. These results indicate that regulation of cyclin G2 is a key mechanism whereby insulin, insulin analogues and IGF-I stimulate cell proliferation.
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Hvid H, Blouin MJ, Birman E, Damgaard J, Poulsen F, Fels JJ, Fledelius C, Hansen BF, Pollak M. Treatment with insulin analog X10 and IGF-1 increases growth of colon cancer allografts. PLoS One 2013; 8:e79710. [PMID: 24260289 PMCID: PMC3832545 DOI: 10.1371/journal.pone.0079710] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 09/24/2013] [Indexed: 12/28/2022] Open
Abstract
Obesity and type 2 diabetes are associated with an increased risk for development of certain forms of cancer, including colon cancer. The publication of highly controversial epidemiological studies in 2009 raised the possibility that use of the insulin analog glargine increases this risk further. However, it is not clear how mitogenic effects of insulin and insulin analogs measured in vitro correlate with tumor growth-promoting effects in vivo. The aim of this study was to examine possible growth-promoting effects of native human insulin, insulin X10 and IGF-1, which are considered positive controls in vitro, in a short-term animal model of an obesity- and diabetes-relevant cancer. We characterized insulin and IGF-1 receptor expression and the response to treatment with insulin, X10 and IGF-1 in the murine colon cancer cell line (MC38 cells) in vitro and in vivo. Furthermore, we examined pharmacokinetics and pharmacodynamics and monitored growth of MC38 cell allografts in mice with diet-induced obesity treated with human insulin, X10 and IGF-1. Treatment with X10 and IGF-1 significantly increased growth of MC38 cell allografts in mice with diet-induced obesity and we can therefore conclude that supra-pharmacological doses of the insulin analog X10, which is super-mitogenic in vitro and increased the incidence of mammary tumors in female rats in a 12-month toxicity study, also increase growth of tumor allografts in a short-term animal model.
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Affiliation(s)
- Henning Hvid
- Diabetes Research Unit, Novo Nordisk A/S, Maaloev, Denmark
- * E-mail:
| | - Marie-José Blouin
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Elena Birman
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | | | - Fritz Poulsen
- Diabetes Research Unit, Novo Nordisk A/S, Maaloev, Denmark
| | | | | | | | - Michael Pollak
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
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Gallagher EJ, Alikhani N, Tobin-Hess A, Blank J, Buffin NJ, Zelenko Z, Tennagels N, Werner U, LeRoith D. Insulin receptor phosphorylation by endogenous insulin or the insulin analog AspB10 promotes mammary tumor growth independent of the IGF-I receptor. Diabetes 2013; 62:3553-60. [PMID: 23835331 PMCID: PMC3781483 DOI: 10.2337/db13-0249] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Endogenous hyperinsulinemia and insulin receptor (IR)/IGF-I receptor (IGF-IR) phosphorylation in tumors are associated with a worse prognosis in women with breast cancer. In vitro, insulin stimulation of the IR increases proliferation of breast cancer cells. However, in vivo studies demonstrating that IR activation increases tumor growth, independently of IGF-IR activation, are lacking. We hypothesized that endogenous hyperinsulinemia increases mammary tumor growth by directly activating the IR rather than the IGF-IR or hybrid receptors. We aimed to determine whether stimulating the IR with the insulin analog AspB10 could increase tumor growth independently of IGF-IR signaling. We induced orthotopic mammary tumors in control FVB/n and hyperinsulinemic MKR mice, and treated them with the insulin analog AspB10, recombinant human IGF-I, or vehicle. Tumors from mice with endogenous hyperinsulinemia were larger and had greater IR phosphorylation, but not IGF-IR phosphorylation, than those from control mice. Chronic AspB10 administration also increased tumor growth and IR (but not IGF-IR) phosphorylation in tumors. IGF-I led to activation of both the IGF-IR and IR and probably hybrid receptors. Our results demonstrate that IR phosphorylation increases tumor growth, independently of IGF-IR/hybrid receptor phosphorylation, and warrant consideration when developing therapeutics targeting the IGF-IR, but not the IR.
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Affiliation(s)
- Emily Jane Gallagher
- Division of Endocrinology, Diabetes and Bone Diseases, Samuel Bronfman Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Nyosha Alikhani
- Division of Endocrinology, Diabetes and Bone Diseases, Samuel Bronfman Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Aviva Tobin-Hess
- Division of Endocrinology, Diabetes and Bone Diseases, Samuel Bronfman Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jeffrey Blank
- Division of Endocrinology, Diabetes and Bone Diseases, Samuel Bronfman Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Nicholas J. Buffin
- Division of Endocrinology, Diabetes and Bone Diseases, Samuel Bronfman Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Zara Zelenko
- Division of Endocrinology, Diabetes and Bone Diseases, Samuel Bronfman Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Norbert Tennagels
- R&D Diabetes Division, Sanofi-Aventis Deutschland, Frankfurt am Main, Germany
| | - Ulrich Werner
- R&D Diabetes Division, Sanofi-Aventis Deutschland, Frankfurt am Main, Germany
| | - Derek LeRoith
- Division of Endocrinology, Diabetes and Bone Diseases, Samuel Bronfman Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
- Corresponding author: Derek LeRoith,
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Maria Rotella C, Pala L, Mannucci E. Role of insulin in the type 2 diabetes therapy: past, present and future. Int J Endocrinol Metab 2013; 11:137-44. [PMID: 24348585 PMCID: PMC3860110 DOI: 10.5812/ijem.7551] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/26/2012] [Accepted: 09/28/2012] [Indexed: 12/29/2022] Open
Abstract
CONTEXT Since 2006 a relevant number of therapeutical algorithms for the management of type 2 diabetes have been proposed, generating a lively debate in the scientific community, particularly on the ideal timing for introduction of insulin therapy and on which drug should be preferred as add-on therapy in patients failing to metformin. At the moment, there is no real consensus. The aim of the present review is to summarize established knowledge and areas for debate with respect to insulin therapy in type 2 diabetes. EVIDENCE ACQUISITION In type 2 diabetic patients, insulin represents a therapy with a long and well-established history, but, considering the modern insulin therapy, several points must be carefully examined. The role played by the introduction of insulin analogues, the choice of insulin regimens, the ongoing debate on insulin and cancer, the cardiovascular effects of insulin, the role of insulin on β-cell protection and the actual clinical perspective in the treatment of the disease. Nevertheless, still many exciting expectations exist: the new insulin analogues, the technological options, the inhaled and oral insulin and the issue of transplantation. CONCLUSIONS Although insulin is the more potent hypoglicemic agent, the availability of a wider spectrum of therapeutic agents, many of which are better tolerated than insulin, has reduced the field of application for insulin treatment; presently, insulin is used only in those who cannot maintain an adequate glycemic control with other drugs. Furthermore, a lively research activity is currently ongoing, in order to make insulin therapy even safer and simpler for patients.
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Affiliation(s)
- Carlo Maria Rotella
- Obesity Agency, University of Florence Medical School, Careggi Teaching Hospital, Firenze, Italy
| | - Laura Pala
- Endocrinolgy Unit , University of Florence Medical School, Careggi Teaching Hospital, Firenze, Italy
| | - Edoardo Mannucci
- Diabetes Agency, University of Florence Medical School, Careggi Teaching Hospital, Firenze, Italy
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Tennagels N, Werner U. The metabolic and mitogenic properties of basal insulin analogues. Arch Physiol Biochem 2013; 119:1-14. [PMID: 23373726 PMCID: PMC3581051 DOI: 10.3109/13813455.2012.754474] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 11/21/2012] [Accepted: 11/26/2012] [Indexed: 12/28/2022]
Abstract
CONTEXT Retrospective, observational studies have reported an association between diabetes treatment with insulin and a higher incidence of cancer. OBJECTIVE Overview the literature for in vitro and in vivo studies of the metabolic and mitogenic properties of basal insulin analogues and assess the implications for clinical use. METHODS Relevant studies were identified through PubMed and congress abstract database searches; data on metabolic and mitogenic signalling in relation to insulin treatment of diabetes are included in this review. RESULTS The balance of evidence shows that although some analogues have demonstrated mitogenic potency in some in vitro studies in cancer cell lines, these findings do not translate to the in vivo setting in animals or to the clinical setting in humans. CONCLUSIONS The current consensus is that there is no clinical or in vivo evidence to indicate that any commercially available insulin analogue has carcinogenic effects. Large-scale, prospective clinical and observational studies will further establish any potential link.
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Affiliation(s)
- Norbert Tennagels
- R&D Diabetes Division, Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany.
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Knudsen L, Hansen BF, Jensen P, Pedersen TÅ, Vestergaard K, Schäffer L, Blagoev B, Oleksiewicz MB, Kiselyov VV, De Meyts P. Agonism and antagonism at the insulin receptor. PLoS One 2012; 7:e51972. [PMID: 23300584 PMCID: PMC3531387 DOI: 10.1371/journal.pone.0051972] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 11/14/2012] [Indexed: 11/29/2022] Open
Abstract
Insulin can trigger metabolic as well as mitogenic effects, the latter being pharmaceutically undesirable. An understanding of the structure/function relationships between insulin receptor (IR) binding and mitogenic/metabolic signalling would greatly facilitate the preclinical development of new insulin analogues. The occurrence of ligand agonism and antagonism is well described for G protein-coupled receptors (GPCRs) and other receptors but in general, with the exception of antibodies, not for receptor tyrosine kinases (RTKs). In the case of the IR, no natural ligand or insulin analogue has been shown to exhibit antagonistic properties, with the exception of a crosslinked insulin dimer (B29-B’29). However, synthetic monomeric or dimeric peptides targeting sites 1 or 2 of the IR were shown to be either agonists or antagonists. We found here that the S961 peptide, previously described to be an IR antagonist, exhibited partial agonistic effects in the 1–10 nM range, showing altogether a bell-shaped dose-response curve. Intriguingly, the agonistic effects of S961 were seen only on mitogenic endpoints (3H-thymidine incorporation), and not on metabolic endpoints (14C-glucose incorporation in adipocytes and muscle cells). The agonistic effects of S961 were observed in 3 independent cell lines, with complete concordance between mitogenicity (3H-thymidine incorporation) and phosphorylation of the IR and Akt. Together with the B29-B’29 crosslinked dimer, S961 is a rare example of a mixed agonist/antagonist for the human IR. A plausible mechanistic explanation based on the bivalent crosslinking model of IR activation is proposed.
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Affiliation(s)
- Louise Knudsen
- Receptor Systems Biology Laboratory, Hagedorn Research Institute, Gentofte, Denmark.
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Hvid H, Fendt SM, Blouin MJ, Birman E, Voisin G, Svendsen AM, Frank R, Vander Heiden MG, Stephanopoulos G, Hansen BF, Pollak M. Stimulation of MC38 tumor growth by insulin analog X10 involves the serine synthesis pathway. Endocr Relat Cancer 2012; 19:557-74. [PMID: 22685267 DOI: 10.1530/erc-12-0125] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Recent evidence suggests that type II diabetes is associated with increased risk and/or aggressive behavior of several cancers, including those arising from the colon. Concerns have been raised that endogenous hyperinsulinemia and/or exogenous insulin and insulin analogs might stimulate proliferation of neoplastic cells. However, the mechanisms underlying possible growth-promoting effects of insulin and insulin analogs in cancer cells in vivo, such as changes in gene expression, are incompletely described. We observed that administration of the insulin analog X10 significantly increased tumor growth and proliferation in a murine colon cancer model (MC38 cell allografts). Insulin and X10 altered gene expression in MC38 tumors in a similar fashion, but X10 was more potent in terms of the number of genes influenced and the magnitude of changes in gene expression. Many of the affected genes were annotated to metabolism, nutrient uptake, and protein synthesis. Strikingly, expression of genes encoding enzymes in the serine synthesis pathway, recently shown to be critical for neoplastic proliferation, was increased following treatment with insulin and X10. Using stable isotopic tracers and mass spectrometry, we confirmed that insulin and X10 increased glucose contribution to serine synthesis in MC38 cells. The data demonstrate that the tumor growth-promoting effects of insulin and X10 are associated with changes in expression of genes involved in cellular energy metabolism and reveal previously unrecognized effects of insulin and X10 on serine synthesis.
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Affiliation(s)
- Henning Hvid
- Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Cote-Ste.-Catherine, Montreal, Quebec, Canada H3T 1E2.
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13
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Hansen BF, Kurtzhals P, Jensen AB, Dejgaard A, Russell-Jones D. Insulin X10 revisited: a super-mitogenic insulin analogue. Diabetologia 2011; 54:2226-31. [PMID: 21633908 DOI: 10.1007/s00125-011-2203-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 04/06/2011] [Indexed: 12/13/2022]
Abstract
The molecular safety of insulin analogues has received a great deal of attention over the last year. In particular, attention has been directed to the mitogenic properties of insulin analogues as compared with human insulin. Understanding the mechanisms implicated in mediating mitogenic effects of insulin is therefore of particular interest. In this review we detail the story of the rapid-acting insulin analogue known as X10, which was the first insulin analogue in clinical development, but ended up being discontinued at an early clinical development stage following findings of mammary tumours in female Sprague-Dawley rats. The molecular characteristics of insulin X10, along with its interaction at both the IGF-1 receptor and the insulin receptor, have provided us with important insights into mechanisms implicated in metabolic and mitogenic signalling of insulin analogues.
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