title: Characterization of SNARE proteins in human pituitary adenomas: targeted secretion inhibitors as a new strategy for the treatment of acromegaly?
abstract: BACKGROUND
  Targeted secretion inhibitors (TSIs), a new class of recombinant biotherapeutic proteins engineered from botulinum toxin, represent a novel approach for treating diseases with excess secretion. They inhibit hormone secretion from targeted cell types through cleavage of SNARE (soluble N-ethylmaleimide-sensitive factor-activating protein receptor) proteins. qGHRH-LH(N)/D is a TSI targeting pituitary somatotroph through binding to the GHRH-receptor and cleavage of the vesicle-associated membrane protein (VAMP) family of SNARE proteins.
  
  
  OBJECTIVE
  Our objective was to study SNARE protein expression in pituitary adenomas and to inhibit GH secretion from somatotropinomas using qGHRH-LH(N)/D.
  
  
  METHODS
  We analyzed human pituitary adenoma analysis for SNARE expression and response to qGHRH-LH(N)/D treatment.
  
  
  METHODS
  The study was conducted in University Hospitals.
  
  
  METHODS
  We used pituitary adenoma samples from 25 acromegaly and 47 nonfunctioning pituitary adenoma patients.
  
  
  RESULTS
  Vesicle-SNARE (VAMP1-3), target-SNARE (syntaxin1, SNAP-23, and SNAP-25), and GHRH-receptor detection with RT-qPCR, immunocytochemistry, and immunoblotting. Assessment of TSI catalytic activity on VAMPs and release of GH from adenoma cells.
  
  
  RESULTS
  SNARE proteins were variably expressed in pituitary samples. In vitro evidence using recombinant GFP-VAMP2&3 or pituitary adenoma lysates suggested sufficient catalytic activity of qGHRH-LH(N)/D to degrade VAMPs, but was unable to inhibit GH secretion in somatotropinoma cell cultures.
  
  
  CONCLUSIONS
  SNARE proteins are present in human pituitary somatotroph adenomas that can be targeted by TSIs to inhibit GH secretion. qGHRH-LH(N)/D was unable to inhibit GH secretion from human somatotroph adenoma cells. Further studies are required to understand how the SNARE proteins drive GH secretion in human somatotrophs to allow the development of novel TSIs with a potential therapeutic benefit.
authors.affiliation: Cancer Research UK Centre, Somers Building, Tremona Road, Southampton, SO16 6YD, UK. eagc1f12@southampton.ac.uk.
authors.forename: Edwin A
authors.initials: EA
authors.lastname: Garcia
authors.forename: Giampaolo
authors.initials: G
authors.lastname: Trivellin
authors.forename: Elena D
authors.initials: ED
authors.lastname: Aflorei
authors.forename: Michael
authors.initials: M
authors.lastname: Powell
authors.forename: Joana
authors.initials: J
authors.lastname: Grieve
authors.forename: Ghassan
authors.initials: G
authors.lastname: Alusi
authors.forename: Luis
authors.initials: L
authors.lastname: Pobereskin
authors.forename: Babak
authors.initials: B
authors.lastname: Shariati
authors.forename: Simon
authors.initials: S
authors.lastname: Cudlip
authors.forename: Federico
authors.initials: F
authors.lastname: Roncaroli
authors.forename: Nigel
authors.initials: N
authors.lastname: Mendoza
authors.forename: Ashley B
authors.initials: AB
authors.lastname: Grossman
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Harper
authors.forename: Márta
authors.initials: M
authors.lastname: Korbonits
mesh_terms: D000172:Acromegaly / Q000209:etiology / Q000517:prevention & control; D000236:Adenoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001905:Botulinum Toxins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D015195:Drug Design; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D013007:Growth Hormone-Releasing Hormone / Q000031:analogs & derivatives / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D049912:Growth Hormone-Secreting Pituitary Adenoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D019382:Human Growth Hormone / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008024:Ligands; D058990:Molecular Targeted Therapy; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010911:Pituitary Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D015202:Protein Engineering; D017434:Protein Structure, Tertiary; D011966:Receptors, LHRH / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D050600:SNARE Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D055571:Secretory Pathway / Q000187:drug effects*; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; C484844:GNRHR protein, human; D008024:Ligands; D009363:Neoplasm Proteins; D011966:Receptors, LHRH; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; C585484:SXN101959; D019382:Human Growth Hormone; C096325:botulinum toxin type D; D013007:Growth Hormone-Releasing Hormone; D001905:Botulinum Toxins