title: Molecular characterisation of long-acting insulin analogues in comparison with human insulin, IGF-1 and insulin X10.
abstract: OBJECTIVE
  There is controversy with respect to molecular characteristics of insulin analogues. We report a series of experiments forming a comprehensive characterisation of the long acting insulin analogues, glargine and detemir, in comparison with human insulin, IGF-1, and the super-mitogenic insulin, X10.
  
  
  METHODS
  We measured binding of ligands to membrane-bound and solubilised receptors, receptor activation and mitogenicity in a number of cell types.
  
  
  RESULTS
  Detemir and glargine each displayed a balanced affinity for insulin receptor (IR) isoforms A and B. This was also true for X10, whereas IGF-1 had a higher affinity for IR-A than IR-B. X10 and glargine both exhibited a higher relative IGF-1R than IR binding affinity, whereas detemir displayed an IGF-1R:IR binding ratio of ≤ 1. Ligands with high relative IGF-1R affinity also had high affinity for IR/IGF-1R hybrid receptors. In general, the relative binding affinities of the analogues were reflected in their ability to phosphorylate the IR and IGF-1R. Detailed analysis revealed that X10, in contrast to the other ligands, seemed to evoke a preferential phosphorylation of juxtamembrane and kinase domain phosphorylation sites of the IR. Sustained phosphorylation was only observed from the IR after stimulation with X10, and after stimulation with IGF-1 from the IGF-1R. Both X10 and glargine showed an increased mitogenic potency compared to human insulin in cells expressing many IGF-1Rs, whereas only X10 showed increased mitogenicity in cells expressing many IRs.
  
  
  CONCLUSIONS
  Detailed analysis of receptor binding, activation and in vitro mitogenicity indicated no molecular safety concern with detemir.
authors.affiliation: Diabetes Research Unit, Novo Nordisk A/S, Måløv, Denmark. bfh@novonordisk.com
authors.forename: Bo F
authors.initials: BF
authors.lastname: Hansen
authors.forename: Tine
authors.initials: T
authors.lastname: Glendorf
authors.forename: Anne C
authors.initials: AC
authors.lastname: Hegelund
authors.forename: Anders
authors.initials: A
authors.lastname: Lundby
authors.forename: Anne
authors.initials: A
authors.lastname: Lützen
authors.forename: Rita
authors.initials: R
authors.lastname: Slaaby
authors.forename: Carsten Enggaard
authors.initials: CE
authors.lastname: Stidsen
mesh_terms: D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000493:pharmacokinetics* / Q000494:pharmacology; D000069057:Insulin Detemir; D000069036:Insulin Glargine; D049528:Insulin, Long-Acting / Q000493:pharmacokinetics* / Q000494:pharmacology; D061386:Insulin, Regular, Human / Q000493:pharmacokinetics* / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D008938:Mitosis / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D007004:Hypoglycemic Agents; D049528:Insulin, Long-Acting; D061386:Insulin, Regular, Human; C084339:LR(3)IGF-I; D000069036:Insulin Glargine; D000069057:Insulin Detemir; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1