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Endocrine Abstracts (2013) 32 P828 | DOI: 10.1530/endoabs.32.P828

ECE2013 Poster Presentations Pituitary–Basic (<emphasis role="italic">Generously supported by IPSEN</emphasis>) (17 abstracts)

Expression of somatostatin receptors, SSTR2A and SSTR5, in 108 pituitary adenomas, using immunohistochemical detection with specific MABs

Laura Chinezu 1 , Alexandre Vasiljevic 2, , Emmanuel Jouanneau 2, , Patrick Francois 4 , Angela Borda 1 , Gerald Raverot 2, & Jacqueline Trouillas 2,


1Department of Histology, University of Medicine and Pharmacy Targu Mures, Targu Mures, Romania; 2Université Lyon 1, Université de Lyon, INSERM, UMR-S1028, Lyon Neuroscience Research Center, Oncoflam Team, Lyon, France; 3Hospices Civils de Lyon, Lyon, France; 4Service de Neurochirurgie, Hôpital Bretonneau, Centre Hospitalier Régional Universitaire de Tours, Tours, France.


Background: Medical treatment of pituitary adenomas with somatostatin analogs depends on tumor type and somatostatin receptor expression. Using polyclonal antibodies, their immunohistochemical (IHC) detection gave conflicting results. Therefore, we studied the IHC expression of SSTR2A and SSTR5 using two specific MABs in five types of pituitary adenomas.

Methods: SSTR2A and SSTR5 expression was studied using two MABs (clone UMB1 and UMB4 for type 2A and 5 respectively) in 108 pituitary adenomas classified into five types: GH (n=60), ACTH (n=15), FSH/LH (n=23), PRL (n=7) and TSH (n=3). A comparative study was performed using two fixatives (Bouin-Hollande and Formol-Zinc) and two technical procedures (manual and automated IHC). GH adenomas were classified as pure or mixte GH/PRL, densely (DG) or sparsely granulated (SG) or according to the percentage of SSTR immunoreactive cells (<25%; 25–75%; >75%). In the other types of adenomas, the SSTR expression was considered as positive when more than 5% of the cells were immunoreactive.

Results: Whatever the fixatives, the techniques or the antibodies used, only specific membrane staining, without cytoplasmic reaction, was observed. Almost all GH adenomas expressed SSTR2A (93.3%) and SSTR5 (81.6%) with high expression (>75%) in 53.6 and 36.5% respectively. No significant difference of SSTR2A and SSTR5 expression was observed between DG and SG, or between pure and mixte GH/PRL adenomas. Moreover, SSTR2A was also expressed in 100% of TSH adenomas, and weakly expressed in 26% of FSH/LH adenomas, ACTH or PRL adenomas being negative. SSTR5 expression was noted in 66% of TSH adenoma but only in 20% of ACTH adenomas, LH/FSH and PRL adenomas being negative.

Conclusion: SSTR2A and SSTR5 were only highly expressed in GH and TSH adenomas. The IHC detection of SSTR with MABs is a reproducible and specific method which can be performed in everyday practice and could be helpful to predict post-operative treatment with somatostatin analogs, in particular in ACTH adenomas.

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