title: Mapping of somatostatin receptor types in GH or/and PRL producing pituitary adenomas.
abstract: BACKGROUND
  Somatostatin is a tetradecapeptide exerting inhibitory action on endocrine and exocrine cell secretion and proliferation. Somatostatin receptors (SST) are widely expressed in various neoplasms including endocrine tumours. Using immunohistochemistry, the expression of SST(1), SST(2A), SST(2B), SST(3), SST(4), and SST(5) was studied in tissue microarrays (TMAs), using a series of 90 human pituitary adenomas producing growth hormone and/or prolactin, including 30 of each somatotroph, lactotroph, and mixed somatotroph/lactotroph adenoma type.
  
  
  METHODS
  For immunohistochemistry, the standard avidin biotin complex method enhanced by tyramide was used, using polyclonal antisera for all SST types. A four point scoring system was used to assess the membranous immunopositivity.
  
  
  RESULTS
  All SST types were positive in all tumour types, showing varying immunoreactivity scores. SST(5) and SST(2A) were the predominant receptors, showing strong expression in high frequency in all three adenoma types. Strong expression of SST(1) was higher in lactotroph adenomas than in other tumour types.
  
  
  CONCLUSIONS
  The immunohistochemical results of SST expression are in agreement with most findings of previous molecular studies. The fact that SST(2A) expression is predominant suggests that pharmaceutical octapeptide somatostatin analogues may act through this receptor, while the role of SST(2B) may be merely synergistic.
authors.affiliation: Department of Pathology, G. Gennimatas Athens General Hospital, Athens, Greece.
authors.forename: E
authors.initials: E
authors.lastname: Thodou
authors.forename: G
authors.initials: G
authors.lastname: Kontogeorgos
authors.forename: D
authors.initials: D
authors.lastname: Theodossiou
authors.forename: M
authors.initials: M
authors.lastname: Pateraki
mesh_terms: D000236:Adenoma / Q000737:chemistry* / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000032:analysis*; D016022:Case-Control Studies; D005260:Female; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008565:Membrane Proteins / Q000032:analysis; D010911:Pituitary Neoplasms / Q000737:chemistry*; D015175:Prolactinoma / Q000737:chemistry; D017481:Receptors, Somatostatin / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; D008565:Membrane Proteins; D017481:Receptors, Somatostatin; C103631:somatostatin receptor 3; C098681:somatostatin receptor subtype-4; C094573:somatostatin receptor 5; D013006:Growth Hormone; C093733:somatostatin receptor 2