Metabolic effect and receptor signalling profile of a non-metabolisable insulin glargine analogue

Abstract

ContextInsulin glargine (GLA) is rapidly metabolized in vivo to metabolite M1, which has in vitro metabolic and mitogenic profiles comparable with human insulin (HI).ObjectiveTo investigate the pharmacologic and signalling profiles of a non-metabolizable analogue (A21Gly,DiD-Arg) insulin (D-GLA).MethodsRats were injected s.c. with 1, 12.5 or 200 U/kg of GLA or D-GLA; blood glucose and phosphorylation status of the insulin receptor (IR), Akt and IGF-1 receptor (IGF1R) in tissue samples were investigated after 1 h. Plasma samples were analysed for insulin by LC-MS/MS.ResultsBlood glucose lowering was prolonged with D-GLA. D-GLA comprised ≥98% of insulin after D-GLA injection; M1 comprised 76–92% after GLA injection. IR and Akt phosphorylation were comparable with GLA and D-GLA. Neither analogue stimulated IGF1R phosphorylation.ConclusionsSuprapharmacological doses of D-GLA did not activate IGF1R in vivo. Mitogenic effects of insulin and insulin analogues might be solely based on IR growth-promoting activity.

Non-metabolisable insulin glargine does not promote breast cancer growth in a mouse model of type 2 diabetes

“…As described in the Methods section, a non-metabolisable form of insulin glargine was generated by replacing the L-arginine resides at position 31 and 32 on the B chain of insulin with D-arginine residues (A21Gly,DiD-Arg) [8]. These D-arginines are not cleaved by carboxypeptidases.…”

“…Previous in vitro studies have found that A21Gly,DiD-Arg has similar affinity for IGF-1R and similar mitogenic potency as insulin glargine in SAOS-2 cells [8]. The A21Gly,DiD-Arg analogue allowed us to model the effects that insulin glargine may have in a tumour-bearing person with the postulated slow rate of metabolism of insulin glargine, and greater exposure to higher circulating levels of the parent glargine than the M1 metabolite.…”

“…Insulin glargine has two L-arginine residues added to the C-terminal of the B chain and an amino acid substitution of glycine (instead of asparagine) at position 21 of the A chain [11]. Non-metabolisable insulin glargine (A21Gly,DiD-Arg) has the same amino acid sequence as insulin glargine but with D-arginine residues at B31 and B32 instead of L-arginine residues [8]. Insulin detemir is also a truncated form of human insulin, lacking threonine at position 30 of the B chain, and with the addition of a tetradecanoic (myristic) acid, acylated to lysine at B29 [12].…”

“…The binding of insulin, insulin glargine, glargine M1 metabolite, A21Gly,DiD-Arg and IGF-1 to insulin receptor isoform A (IR-A) and IR-B were analysed using a competitive binding assay, using methods as previously described [8, 9], except that for these assays the plasma membranes were enriched from Chinese hamster ovary cells overexpressing either human IR-A or IR-B, and competitive binding assays were performed using 110 pmol A14[ 125 I]-insulin.…”

“…However, when glargine is injected into individuals with type 2 diabetes it is rapidly metabolised into intermediate metabolites, the M1 and M2 metabolites. The M1 metabolite accounts for >90% of plasma insulin content after administration of insulin glargine to animals and patients, whereas M2 metabolite is usually undetectable, and parent glargine accounts for <10% of plasma insulin [7, 8]. In vitro, the M1 metabolite has an affinity for IGF-1R similar to that of human insulin, and has equivalent mitogenic potency to that of human insulin [9].…”