Correlation of in vitro and in vivo somatotropic adenoma responsiveness to somatostatin analogs and dopamine agonists with immunohistochemical evaluation of somatostatin and dopamine receptors and electron microscopy

Diego Ferone, Wouter W. De Herder, Rosario Pivonello, Johan M. Kros, Peter M. Van Koetsveld, Ton De Jong, Francesco Minuto, Annamaria Colao, Steven W J Lamberts, Leo J. Hofland

Research output: Contribution to journalArticle

Abstract

Objective and Patients: Twenty-four pituitary adenomas from acromegalic patients (13 females, 11 males; age range 19-65 yr) were characterized for somatostatin receptor subtype 2A (sst2A), dopamine D2 receptor (D2R), GH, and prolactin (PRL) expression by immunohistochemistry, and results correlated with the in vitro and in vivo hormone responses to octreotide and quinagolide. In nine cases, GH and PRL content was further studied by immunoelectron microscopy. Results: Immunoreactivity was semiquantitatively scored as 2 (>50% stained cells), 1 (10-50% stained cells), and 0 (2A was scored as 2 in 13 cases, 1 in 10, and 0 in one; D2R was scored as 2 in 13 cases, 1 in nine, and 0 in 2; GH was 2 in 15 cases and 1 in nine; PRL was 2 in six cases, 1 in 13, and 0 in 5. Sst2A was positively correlated with in vitro (P = 0.003) and in vivo (P = 0.006) percent GH suppression by octreotide and with the chronic suppression of IGF-I by somatostatin analogs (P =0.008). D2R was positively correlated with in vitro percent GH (P =0.000) and PRL (P =0.005) suppression by quinagolide. Electron microscopy revealed two pure somatotroph adenomas, five somatomammotrophs with a variable coexpression of GH and PRL in the same cells, and two tumors consisting of mixed cell types, which were less sensitive to quinagolide and octreotide. Conclusion: Sst2A and D2R are frequently coexpressed in adenomas from acromegalic patients, and immunohistochemistry may be helpful in characterizing receptor expression in pituitary adenomas to select patients responsive to different treatments.

Original languageEnglish
Pages (from-to)1412-1417
Number of pages6
JournalJournal of Clinical Endocrinology and Metabolism
Volume93
Issue number4
DOIs
Publication statusPublished - Apr 2008

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology, Diabetes and Metabolism

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