ECE2006 Poster Presentations Endocrine tumours and neoplasia (116 abstracts)
Somatostatin receptor subtypes 1–5 in pituitary tumors of various etiologies: investigation by immunohistochemistry
N Unger 1 , I Serdiuk 1 , W Saeger 2 , H Wiedemeyer 3 , J Van de Nes 4 , S Schulz 5 , D Stolke 3 , K Mann 1 & S Petersenn 1
1Division of Endocrinology, Medical Center, University of Essen, Essen, Germany; 2Institute of Pathology, Marienhospital, Hamburg, Germany; 3Department of Neurosurgery, University of Essen, Essen, Germany; 4Institute of Pathology, University of Essen, Essen, Germany; 5Institute of Pharmacology and Toxicology, University of Magdeburg, Magdeburg, Germany.
For somatostatin, five receptor subtypes (sst1-5) have been identified that are widely distributed in various endocrine tissues and tumors. Potent somatostatin analogs like octreotide, lanreotide and the new multiligand SOM230 – with different binding properties to the receptor subtypes - have been developed. We examined somatostatin receptor protein expression in 134 pituitary tumors of various etiologies. Immunostaining was performed with specific polyclonal antibodies for sst1-5. Seventeen growth hormone-producing adenomas (GH), 23 ACTH-producing adenomas (CUSH), 36 prolactinomas (PROL) and 47 non-functioning adenomas (NFA), as well as 11 atypical adenomas (AA) were investigated. Staining pattern, distribution and subcellular localization of ssts were evaluated. A tissue known to stain positively for the respective sst was used as a positive control. About 70% of GH were positively stained for sst2A. About 20% expressed sst1 and 6% were positive for each sst3, 4 and 5. Sst5 was detected in >60% of positively stained tumor cells, while sst1, 3 and 4 were found in <60% of tumor cells. About 11% of PROL expressed sst2A. Sst4 was found in about 6% of PROL and about 3% were positively stained for each sst1, 3 and 5.Seventy percent of CUSH were positively stained for sst2A. Interestingly, sst4 was detected in 40% of CUSH. Sst1 and 3 were found in about 10% and sst5 was detected in 5% of CUSH only. About 40% of NFA were positive for sst2A, about 30% for sst3, 20% for sst1 and 4, and 11% for sst5. AA revealed an sst2A-immunostaining in approx. 30%. Sst3 and 4 were expressed in 20% of AA, whereas sst1 and sst5 were not detected. In pituitary tumors, Somatostatin receptor proteins are expressed with tumor-specific distribution pattern. This may offer new diagnostic and therapeutic possibilities with multiligand or subtype specific somatostatin analogs.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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