GLP-1 receptor agonists synergize with DYRK1A inhibitors to potentiate functional human β cell regeneration

Abstract

Glucagon-like peptide-1 receptor (GLP1R) agonists and dipeptidyl peptidase 4 inhibitors are widely prescribed diabetes drugs due to their ability to stimulate insulin secretion from remaining β cells and to reduce caloric intake. Unfortunately, they fail to increase human β cell proliferation. Small-molecule inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) are able to induce adult human β cell proliferation, but rates are modest (~2%), and their specificity to β cells is limited. Here, we provide evidence that combining any member of the GLP1R agonist class with any member of the DYRK1A inhibitor class induces a synergistic increase in human β cell replication (5 to 6%) accompanied by an actual increase in numbers of human β cells. GLP1R agonist–DYRK1A inhibitor synergy required combined inhibition of DYRK1A and an increase in cAMP and did not lead to β cell dedifferentiation. These beneficial effects on proliferation were seen in both normal human β cells and β cells derived from individuals with type 2 diabetes. The ability of the GLP1R agonist–DYRK1A inhibitor combination to enhance human β cell proliferation, human insulin secretion, and blood glucose control extended in vivo to studies of human islets transplanted into euglycemic and streptozotocin-diabetic immunodeficient mice. No adverse events were observed in the mouse studies during a 1-week period. Because of the relative β cell specificity of GLP1R agonists, the combination provides an improved, although not complete, degree of human β cell specificity.

Human Beta Cell Mass Expansion In Vivo With A Harmine and Exendin-4 Combination: Quantification and Visualization By iDISCO+ 3D Imaging

“…We find that harmine and exendin-4 co-administration increases human beta cell mass by a factor of 7fold over three months, without significant alterations in alpha cell mass. These observations, together with prior reports that the harmine and exendin-4 combination enhances human beta cell differentiation and function in vitro and in vivo (1)(2)(3), provide an attractive new path to diabetes treatment, as well as a rigorous, entirely novel and reproducible method to quantify human beta cell mass and response to potential future therapies in vivo.…”

“…The human beta cell proliferation rates from harmine (1), harmine plus TGFβ inhibitors (2) and harmine plus exendin-4 3are substantially higher in vitro than they are in vivo. For example, harmine alone induces a beta cell Ki67 labeling index in human islets in vitro of 1.5-2.5% (1-5), harmine plus TGFβ inhibitors yields 5-8% (2), and harmine plus exendin-4 yields a similar 5-8% Ki67 labeling index in vitro (3). The corresponding Ki67 labeling indices in in vivo studies grafts are 0.7% for harmine alone, 1.5% for harmine plus TGFβ inhibitors, and 1.5% for harmine plus exendin-4 (1-3).…”

“…Harmine also increases proliferation in alpha cells in vitro (1)(2)(3)(4)17). To examine whether the increase in human beta cell mass was accompanied by an increase in alpha cell mass, we analyzed alpha cell volume in the same samples described in Fig.…”

Structure–Activity Relationships and Biological Evaluation of 7-Substituted Harmine Analogs for Human β-Cell Proliferation

“…After assessing the effect of these modifications on DYRK1A inhibition, we next explored the structure-activity relationships for in vitro β-cell proliferation activity of the most potent 7-O-substituted DYRK1A inhibitor harmine analogs. Compounds 1-2b and 1-3b, with DYRK1A inhibitory activities (IC 50 ) of 89 and 91 nM, respectively, were studied as previously reported [5,39,[43][44][45], for their ability to induce human β-cell proliferation in vitro as assessed by Ki-67-insulin co-immunolabeling after 4 days, our standard assay protocol [49] ( Figure 4A). Both the harmine analogues, 1-2b and 1-3b exhibited human β-cell proliferation at 10 µM ( Figure 4A).…”

“…We first determined the effect of these modifications on DYRK1A inhibition, measured by FRET-based LanthaScreen ® Eu Kinase Binding Assay [42]. Since the overall goal of the project is to develop DYRK1A inhibitors that can induce β-cells to proliferate, we also assayed potent 7-substituted harmine analogs for human β-cell proliferation by quantifying Ki67 immunolabeling in beta cells [5,39,[43][44][45].…”