title: In vitro effects of mycophenolic acid on survival, function, and gene expression of pancreatic beta-cells.
abstract: Post-transplant diabetes mellitus represents an important complication of prolonged immunosuppressive treatment after solid organ transplantation. The immunosuppressive toxicity, responsible for a persistent impairment of glucose metabolism in pancreatic islet-transplanted patients, is mainly attributed to calcineurin inhibitors and steroids, while other immunosuppressive molecules (azathioprine and mycophenolic acid, MPA) are considered not to have a toxic effect. In the present study, in vitro effects of MPA have been investigated in mouse beta-cell lines (βTC-1 and βTC-6) and in purified human pancreatic islets. βTC-1, βTC-6, and human pancreatic islets were exposed to various concentrations of MPA for different times. Consequently, we evaluated the viability, the induction of apoptosis, the glucose-stimulated insulin secretion, and the expression of β-cell function genes (Isl1, Pax6, Glut-2, glucokinase) and apoptosis-related genes (Bax and Bcl2). βTC-1, βTC-6, and human islets treated, respectively, for 48 and 72 h with 15-30 nM MPA showed altered islet architecture, as compared with control cells. We observed for βTC-1 and βTC-6 almost 70% reduction in cell viability; three to sixfold induction of TUNEL/apoptotic-positive cells quantified by FACS analysis. A twofold increase in apoptotic cells was observed in human islets after MPA exposure associated with strong inhibition of glucose-stimulated insulin secretion. Furthermore, we showed significant down-regulation of gene expression of molecules involved in β-cell function and increase rate between Bax/Bcl2. Our data demonstrate that MPA has an in vitro diabetogenic effect interfering at multiple levels with survival and function of murine and human pancreatic β-cells.
authors.affiliation: Department of Internal Medicine, Diabetes Unit, Endocrine and Metabolic Sciences and Biochemistry, University of Siena, Viale Bracci 18, 53100 Siena, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Gallo
authors.forename: M
authors.initials: M
authors.lastname: Natale
authors.forename: F
authors.initials: F
authors.lastname: Vendrame
authors.forename: U
authors.initials: U
authors.lastname: Boggi
authors.forename: F
authors.initials: F
authors.lastname: Filipponi
authors.forename: P
authors.initials: P
authors.lastname: Marchetti
authors.forename: F
authors.initials: F
authors.lastname: Laghi Pasini
authors.forename: F
authors.initials: F
authors.lastname: Dotta
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D051273:Glucose Transporter Type 2 / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects; D008297:Male; D051379:Mice; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000494:pharmacology*; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D055815:Young Adult
chemical_list: D005136:Eye Proteins; D051273:Glucose Transporter Type 2; D018398:Homeodomain Proteins; D007166:Immunosuppressive Agents; D007328:Insulin; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D012097:Repressor Proteins; D009173:Mycophenolic Acid