title: Effect of insulin analogues on insulin/IGF1 hybrid receptors: increased activation by glargine but not by its metabolites M1 and M2.
abstract: BACKGROUND
  In diabetic patients, the pharmacokinetics of injected human insulin does not permit optimal control of glycemia. Fast and slow acting insulin analogues have been developed, but they may have adverse properties, such as increased mitogenic or anti-apoptotic signaling. Insulin/IGF1 hybrid receptors (IR/IGF1R), present in most tissues, have been proposed to transmit biological effects close to those of IGF1R. However, the study of hybrid receptors is difficult because of the presence of IR and IGF1R homodimers. Our objective was to perform the first study on the pharmacological properties of the five marketed insulin analogues towards IR/IGF1R hybrids.
  
  
  METHODS
  To study the effect of insulin analogues on IR/IGF1R hybrids, we used our previously developed Bioluminescence Resonance Energy Transfer (BRET) assay that permits specific analysis of the pharmacological properties of hybrid receptors. Moreover, we have developed a new, highly sensitive BRET-based assay to monitor phophatidylinositol-3 phosphate (PIP(3)) production in living cells. Using this assay, we performed a detailed pharmacological analysis of PIP(3) production induced by IGF1, insulin and insulin analogues in living breast cancer-derived MCF-7 and MDA-MB231 cells.
  
  
  RESULTS
  Among the five insulin analogues tested, only glargine stimulated IR/IGF1R hybrids with an EC50 that was significantly lower than insulin and close to that of IGF1. Glargine more efficiently stimulated PIP(3) production in MCF-7 cells but not in MDA-MB231 cells as compared to insulin. In contrast, glargine metabolites M1 and M2 showed lower potency for hybrid receptors stimulation, PIP(3) production, Akt and Erk1/2 phosphorylation and DNA synthesis in MCF-7 cells, compared to insulin.
  
  
  CONCLUSIONS
  Glargine, possibly acting through IR/IGF1R hybrids, displays higher potency, whereas its metabolites M1 and M2 display lower potency than insulin for the stimulation of proliferative/anti-apoptotic pathways in MCF-7 cells.
authors: Institut Cochin, Université Paris Descartes, CNRS (UMR8104), Paris, France.
authors: Cécile
authors: C
authors: Pierre-Eugene
authors: Patrick
authors: P
authors: Pagesy
authors: Tuyet Thu
authors: TT
authors: Nguyen
authors: Marion
authors: M
authors: Neuillé
authors: Georg
authors: G
authors: Tschank
authors: Norbert
authors: N
authors: Tennagels
authors: Cornelia
authors: C
authors: Hampe
authors: Tarik
authors: T
authors: Issad
mesh_terms: D057809:HEK293 Cells; D006801:Humans; D000069036:Insulin Glargine; D049528:Insulin, Long-Acting / Q000378:metabolism* / Q000494:pharmacology*; D061986:MCF-7 Cells; D018129:Phosphatidylinositol Phosphates / Q000096:biosynthesis; D017526:Receptor, IGF Type 1 / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D049528:Insulin, Long-Acting; D018129:Phosphatidylinositol Phosphates; D011993:Recombinant Fusion Proteins; C055525:phosphatidylinositol 3-phosphate; D000069036:Insulin Glargine; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin