Differential somatostatin receptor (SSTR) 1-5 expression and downstream effectors in histologic subtypes of growth hormone pituitary tumors.

Authors :: Kiseljak-Vassiliades K
Xu M
Mills TS
Smith EE
Silveira LJ
Lillehei KO
Kerr JM
Kleinschmidt-DeMasters BK
Wierman ME
Source :: Molecular and cellular endocrinology [Mol Cell Endocrinol] 2015 Dec 05; Vol. 417, pp. 73-83. Date of Electronic Publication: 2015 Sep 21.
Publication Year :: 2015
Abstract: Purpose: 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.<br />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.<br />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.<br />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.<br /> (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

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