title: Beneficial effects of growth hormone-releasing hormone agonists on rat INS-1 cells and on streptozotocin-induced NOD/SCID mice.
abstract: Agonists of growth hormone-releasing hormone (GHRH) have been previously reported to promote growth, function, and engraftment of islet cells following transplantation. Here we evaluated recently synthesized GHRH agonists on the proliferation and biological functions of rat pancreatic β-cell line (INS-1) and islets. In vitro treatment of INS-1 cells with GHRH agonists increased cell proliferation, the expression of cellular insulin, insulin-like growth factor-1 (IGF1), and GHRH receptor, and also stimulated insulin secretion in response to glucose challenge. Exposure of INS-1 cells to GHRH agonists, MR-356 and MR-409, induced activation of ERK and AKT pathways. Agonist MR-409 also significantly increased the levels of cellular cAMP and the phosphorylation of cAMP response element binding protein (CREB) in INS-1 cells. Treatment of rat islets with agonist, MR-409 significantly increased cell proliferation, islet size, and the expression of insulin. In vivo daily s.c. administration of 10 μg MR-409 for 3 wk dramatically reduced the severity of streptozotocin (STZ)-induced diabetes in nonobese diabetic severe combined immunodeficiency (NOD/SCID) mice. The maximal therapeutic benefits with respect to the efficiency of engraftment, ability to reach normoglycemia, gain in body weight, response to high glucose challenge, and induction of higher levels of serum insulin and IGF1 were observed when diabetic mice were transplanted with rat islets preconditioned with GHRH agonist, MR-409, and received additional treatment with MR-409 posttransplantation. This study provides an improved approach to the therapeutic use of GHRH agonists in the treatment of diabetes mellitus.
authors.affiliation: Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL 33136; Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125; South Florida Veterans Affairs Foundation for Research and Education, Miami, FL 33125; xyzhang@med.miami.edu andrew.schally@va.gov.
authors.forename: Xianyang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL 33136; Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125; South Florida Veterans Affairs Foundation for Research and Education, Miami, FL 33125;
authors.forename: Tengjiao
authors.initials: T
authors.lastname: Cui
authors.affiliation: Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125; South Florida Veterans Affairs Foundation for Research and Education, Miami, FL 33125;
authors.forename: Jinlin
authors.initials: J
authors.lastname: He
authors.affiliation: Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL 33136; Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125;
authors.forename: Haibo
authors.initials: H
authors.lastname: Wang
authors.affiliation: Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL 33136; Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125; South Florida Veterans Affairs Foundation for Research and Education, Miami, FL 33125;
authors.forename: Renzhi
authors.initials: R
authors.lastname: Cai
authors.affiliation: Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125; Department of Medicine III, University Hospital Carl Gustav Carus, 01307 Dresden, Germany;
authors.forename: Petra
authors.initials: P
authors.lastname: Popovics
authors.affiliation: Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125; South Florida Veterans Affairs Foundation for Research and Education, Miami, FL 33125;
authors.forename: Irving
authors.initials: I
authors.lastname: Vidaurre
authors.affiliation: Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, Miami, FL 33136; Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125;
authors.forename: Wei
authors.initials: W
authors.lastname: Sha
authors.affiliation: Department of Medicine III, University Hospital Carl Gustav Carus, 01307 Dresden, Germany;
authors.forename: Janine
authors.initials: J
authors.lastname: Schmid
authors.affiliation: Department of Medicine III, University Hospital Carl Gustav Carus, 01307 Dresden, Germany;
authors.forename: Barbara
authors.initials: B
authors.lastname: Ludwig
authors.affiliation: Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125; South Florida Veterans Affairs Foundation for Research and Education, Miami, FL 33125; Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136; Division of Hematology and Oncology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL 33136;
authors.forename: Norman L
authors.initials: NL
authors.lastname: Block
authors.affiliation: Department of Medicine III, University Hospital Carl Gustav Carus, 01307 Dresden, Germany;
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Bornstein
authors.affiliation: Endocrine, Polypeptide, and Cancer Institute, Veterans Affairs Medical Center, Miami, FL 33125; South Florida Veterans Affairs Foundation for Research and Education, Miami, FL 33125; Department of Pathology, Miller School of Medicine, University of Miami, Miami, FL 33136; Division of Hematology and Oncology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL 33136; Division of Endocrinology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL 33136 xyzhang@med.miami.edu andrew.schally@va.gov.
authors.forename: Andrew V
authors.initials: AV
authors.lastname: Schally
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D013007:Growth Hormone-Releasing Hormone / Q000819:agonists*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D051381:Rats; D013311:Streptozocin
chemical_list: D013311:Streptozocin; D013007:Growth Hormone-Releasing Hormone
keywords: GHRH agonists; INS-1; diabetes; signaling pathways; transplantation