Endocrine Abstracts (2013) 32 P834 | DOI: 10.1530/endoabs.32.P834

No correlation between somatostatine 2 receptor expression analyzed by RNA in-situ hybridization and real-time qRT-PCR in clinically non-functioning pituitary adenomas

Filip Gabalec1, Ales Kohout2, Jan Laco2, Monika Drastikova3, Martin Beranek3, David Netuka4, Vaclav Masopust4, Tomas Cesak5 & Jan Cap1


14th Department of Internal Medicine, Faculty of Medicine in Hradec Kralove, Charles University Hospital, Hradec Kralove, Czech Republic; 2Fingerland’s Department of Pathology, Faculty of Medicine in Hradec Kralove, Charles University Hospital, Hradec Kralove, Czech Republic; 3Faculty of Medicine in Hradec Kralove, Institute of Clinical Biochemistry and Diagnostics, Charles University Hospital, Hradec Kralove, Czech Republic; 4Department of Neurosurgery, 1st Faculty of Medicine, Central Military Hospital, Charles University, Prague, Czech Republic; 5Department of Neurosurgery, Faculty of Medicine in Hradec Kralove, Charles University Hospital, Hradec Kralove, Czech Republic.


Objective: The aim of this study was to quantitatively estimate SSTR2 in clinically non-functioning pituitary adenomas (CNFAs) with use of RNA in-situ hybridization (ISH) and quantitative real-time RT-PCR and correlate the results of both methods.

Methods: A standard histological and immunohistochemical examination was performed on the resected pituitary tumour. Afterwards in-situ hybridization for somatostatine 2 receptor (SSTR2) RNA was performed manually using the RNAscope® 2.0 FFPE Assay (Advanced Cell Diagnostics, Inc., Hayward, CA, USA) on formalin fixed and paraffin embedded tissue sections. Small part of the same tumour resected during operation and stored in RNAlater was used for quantitative real-time RT-PCR.

Results: A 25 adenomas with SSTR2 mRNA expression in qRT-PCR were chosen for further evaluation with RNA ISH. SSTR2 mRNA was expressed in all adenomas from 1413–148 680 copies/5 μl cDNA; the median of relative quantity (after normalization to housekeeping gene GUS) for SSTR2 was 111%. In contrast to qRT-PCR immunostaining was positive only in nine adenomas with the use of RNA ISH. Positive cases were subsequently semi-quantitatively assessed according to the manufacturer’s scoring guideline as follows: 1 adenoma with 1+, 5 with 2+ and 3 with 3+. No adenoma scored 4+ although high expression of SSTR2 mRNA was present. We did not find any correlation between data (Spearman’s rank correlation coefficient 0.243).

Conclusion: Use of somatostatine analogues or dopastatins remains controversial in CNFAs. Verification of SSTR presence before use of drug treatment should be useful. Both RNA ISH and qRT-PCR have their pitfalls. In our case, we did show no correlation between these methods. RNA ISH is definitely less sensitive and specific. We think that interpretation of results for SSTR2 expression in RNA ISH and qRT-PCR should be very careful.

Project is supported by Ministry of Health Project No. NT/11344-4/2010.