title: Differential somatostatin receptor (SSTR) 1-5 expression and downstream effectors in histologic subtypes of growth hormone pituitary tumors.
abstract: OBJECTIVE
  The aim of this study was to examine whether differential expression of somatostatin receptors (SSTR) 1-5 and downstream effectors are different in densely (DG) and sparsely (SG) granulated histological growth hormone (GH) pituitary tumor subtypes.
  
  
  METHODS
  The study included 33 acromegalic patients with 23 DG and 10 SG tumors. SSTR1-5 were measured by qPCR and immunoblotting. Signaling candidates downstream of SSTR2 were also assessed.
  
  
  RESULTS
  SSTR2 mRNA and protein levels were significantly higher in DG compared to SG tumors. Downstream of SSTR2, p27(kip1) was decreased (2.6-fold) in SG compared to DG tumors, suggesting a potential mechanism of SSA resistance in SG tumors with intact SSTR2 expression. Re-expression of E-cadherin in GH pituitary cell increased p27(kip1) levels.
  
  
  CONCLUSIONS
  Histological subtyping correlated with SSTR2, E cadherin and p27(kip) protein levels and these may serve as useful biomarkers in GH tumors to predict behavior and response to therapy with SSA.
authors.affiliation: Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Research Service Veterans Affairs Medical Center, Denver, CO 80220, USA. Electronic address: katja.kiseljak-vassiliades@ucdenver.edu.
authors.forename: Katja
authors.initials: K
authors.lastname: Kiseljak-Vassiliades
authors.affiliation: Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
authors.forename: Mei
authors.initials: M
authors.lastname: Xu
authors.affiliation: Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
authors.forename: Taylor S
authors.initials: TS
authors.lastname: Mills
authors.affiliation: Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Smith
authors.affiliation: Division of Biostatistics and Bioinformatics, National Jewish Health, Denver, CO 80206, USA.
authors.forename: Lori J
authors.initials: LJ
authors.lastname: Silveira
authors.affiliation: Department of Neurosurgery, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
authors.forename: Kevin O
authors.initials: KO
authors.lastname: Lillehei
authors.affiliation: Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
authors.forename: Janice M
authors.initials: JM
authors.lastname: Kerr
authors.affiliation: Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Department of Neurosurgery, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
authors.forename: B K
authors.initials: BK
authors.lastname: Kleinschmidt-DeMasters
authors.affiliation: Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Research Service Veterans Affairs Medical Center, Denver, CO 80220, USA.
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Wierman
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D017481:Receptors, Somatostatin / Q000235:genetics* / Q000378:metabolism*; D012189:Retrospective Studies; D015398:Signal Transduction
chemical_list: D014408:Biomarkers, Tumor; C436291:CDKN1B protein, human; D015820:Cadherins; D017481:Receptors, Somatostatin; C574734:SSTR2 protein, human; D050760:Cyclin-Dependent Kinase Inhibitor p27
keywords: Acromegaly; Dense GH tumors; Somatostatin receptor; Sparse GH tumors