Somatostatin receptor subtypes mRNA in TSH-secreting pituitary adenomas: a case showing a dramatic reduction in tumor size during short octreotide treatment.

Abstract

TSH-secreting adenoma is a rare pituitary adenoma, and the expression levels of the specific subtypes of somatostatin receptors (sstr) mRNAs have remained obscure. To determine the quantitative expression of the sstr1-5 mRNAs in TSH-secreting adenomas that may be related to the efficacy of treatment with a somatostatin analogue, expression of the sstr1-5 mRNAs was examined and compared in TSH-secreting adenomas and other pituitary adenomas. The pituitary adenomas were obtained at transsphenoidal surgery from 4 cases of TSH-secreting adenoma, including 1 patient showing a significant shrinkage of the tumor size after only 10 days of octreotide treatment, 2 patients without tumor size reduction and 1 patient without treatment, and 5 GH-secreting adenomas, 6 prolactinomas, 5 nonfunctioning adenomas, 4 ACTH-secreting adenomas and normal pituitaries at autopsy from 4 normal subjects. In comparison to the normal pituitary, sstr2A>sstr1>sstr5>sstr3 mRNAs were expressed in the TSH-secreting adenomas examined. No expression of sstr2B or sstr4 mRNA was observed. The expression level of sstr2 mRNA was significantly higher than those in normal pituitary, prolactinomas, ACTH-secreting and nonfunctioning pituitary adenomas. The patient with marked shrinkage of the tumor showed the highest expression of both sstr2 and sstr5 mRNAs among all the cases of pituitary adenoma. A TSH-secreting tumor without shrinkage showed a similar expression level of sstr2 mRNA. These findings demonstrated that TSH-secreting adenomas express sstr1, 2A, 3 and 5 mRNAs, predominantly sstr2A, and in addition to the expression of sstr2 mRNA, the expression level of sstr5 mRNA may be a factor affecting the tumor shrinkage by somatostatin analogues against TSH-secreting adenomas.

• Authors: Kazuhiko Horiguchi, Masanobu Yamada, Ryohei Umezawa, Teturo Satoh, Koshi Hashimoto, Masahiko Tosaka, Shozo Yamada, Masatomo Mori
• Journal: Endocrine journal (Endocr J) Vol. 54 Issue 3 Pg. 371-8 (Jun 2007) ISSN: 0918-8959 [Print] Japan
• PMID: 17420609 (Publication Type: Case Reports, Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents, Hormonal
• Protein Isoforms
• RNA, Messenger
• Receptors, Somatostatin
• Octreotide

Topics

• Adenoma (drug therapy, genetics, metabolism, pathology)
• Adult
• Aged
• Aged, 80 and over
• Antineoplastic Agents, Hormonal (therapeutic use)
• Female
• Gene Expression Regulation, Neoplastic (drug effects)
• Humans
• Male
• Middle Aged
• Octreotide (therapeutic use)
• Pituitary Neoplasms (drug therapy, genetics, metabolism, pathology)
• Protein Isoforms (genetics, metabolism)
• RNA, Messenger (metabolism)
• Receptors, Somatostatin (genetics, metabolism)
• Thyrotrophs (metabolism, pathology)
• Time Factors
• Tumor Burden (drug effects)