Somatostatin receptor subtypes mRNA in TSH-secreting pituitary adenomas: a case showing a dramatic reduction in tumor size during short octreotide treatment.
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.
Horiguchi
Kazuhiko
K
Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan.
Yamada
Masanobu
M
Umezawa
Ryohei
R
Satoh
Teturo
T
Hashimoto
Koshi
K
Tosaka
Masahiko
M
Yamada
Shozo
S
Mori
Masatomo
M
D000236:Adenoma / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use*; D010911:Pituitary Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017481:Receptors, Somatostatin / Q000235:genetics* / Q000378:metabolism; D052684:Thyrotrophs / Q000378:metabolism / Q000473:pathology*; D013997:Time Factors; D047368:Tumor Burden / Q000187:drug effects*
D018931:Antineoplastic Agents, Hormonal; D020033:Protein Isoforms; D012333:RNA, Messenger; D017481:Receptors, Somatostatin; D015282:Octreotide