title: Lack of Ubiquitin Specific Protease 8 (USP8) Mutations in Canine Corticotroph Pituitary Adenomas.
abstract: OBJECTIVE
  Cushing's disease (CD), also known as pituitary-dependent hyperadrenocorticism, is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary tumours. Affected humans and dogs have similar clinical manifestations, however, the incidence of the canine disease is thousand-fold higher. This makes the dog an obvious model for studying the pathogenesis of pituitary-dependent hyperadrenocorticism. Despite certain similarities identified at the molecular level, the question still remains whether the two species have a shared oncogenetic background. Recently, hotspot recurrent mutations in the gene encoding for ubiquitin specific protease 8 (USP8) have been identified as the main driver behind the formation of ACTH-secreting pituitary adenomas in humans. In this study, we aimed to verify whether USP8 mutations also play a role in the development of such tumours in dogs.
  
  
  METHODS
  Presence of USP8 mutations was analysed by Sanger and PCR-cloning sequencing in 38 canine ACTH-secreting adenomas. Furthermore, the role of USP8 and EGFR protein expression was assessed by immunohistochemistry in a subset of 25 adenomas.
  
  
  RESULTS
  None of the analysed canine ACTH-secreting adenomas presented mutations in the USP8 gene. In a subset of these adenomas, however, we observed an increased nuclear expression of USP8, a phenotype characteristic for the USP8 mutated human tumours, that correlated with smaller tumour size but elevated ACTH production in those tumours.
  
  
  CONCLUSIONS
  Canine ACTH-secreting pituitary adenomas lack mutations in the USP8 gene suggesting a different genetic background of pituitary tumourigenesis in dogs. However, elevated nuclear USP8 protein expression in a subset of tumours was associated with a similar phenotype as in their human counterparts, indicating a possible end-point convergence of the different genetic backgrounds in the two species. In order to establish the dog as a useful animal model for the study of CD, further comprehensive studies are needed.
authors.affiliation: Department of Internal Medicine I, Division of Endocrinology and Diabetes, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.
authors.forename: Silviu
authors.initials: S
authors.lastname: Sbiera
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Marianna A
authors.initials: MA
authors.lastname: Tryfonidou
authors.affiliation: Department of Internal Medicine I, Division of Endocrinology and Diabetes, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.
authors.forename: Isabel
authors.initials: I
authors.lastname: Weigand
authors.affiliation: Departement of Pathobiology, Veterinary Pathology Diagnostic Center, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Guy C M
authors.initials: GC
authors.lastname: Grinwis
authors.affiliation: Laboratory for Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Broeckx
authors.affiliation: Clinical Chemistry and Laboratory Medicine, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Herterich
authors.affiliation: Department of Internal Medicine I, Division of Endocrinology and Diabetes, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.
authors.forename: Bruno
authors.initials: B
authors.lastname: Allolio
authors.affiliation: Clinical Chemistry and Laboratory Medicine, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Deutschbein
authors.affiliation: Department of Internal Medicine I, Division of Endocrinology and Diabetes, University Hospital Würzburg, University of Würzburg, Würzburg, Germany.|Laboratory for Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium.|Comprehensive Cancer Center Mainfranken, University of Würzburg, Würzburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Fassnacht
authors.affiliation: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Björn P
authors.initials: BP
authors.lastname: Meij
mesh_terms: D049913:ACTH-Secreting Pituitary Adenoma / Q000235:genetics / Q000662:veterinary*; D000818:Animals; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs; D010450:Endopeptidases / Q000235:genetics*; D005260:Female; D008297:Male; D009154:Mutation; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D043222:Ubiquitin Thiolesterase / Q000235:genetics*
chemical_list: D010450:Endopeptidases; D043222:Ubiquitin Thiolesterase