Expression of Pit-1 and growth hormone-releasing hormone receptor mRNA in human pituitary adenomas: difference among functioning, silent, and other nonfunctioning adenomas.
We analyzed the expression of Pit-1 and growth hormone-releasing hormone receptor (GHRH-R) mRNA in various types of functioning and nonfunctioning adenomas using a quantitative reverse transcriptase polymerase chain reaction (RT-PCR) method. Among clinically nonfunctioning adenomas, tumors considered as silent adenomas were reclassified on a pathologic basis. Competitive RT-PCR showed that the levels of Pit-1 and GHRH-R mRNA expression in silent somatotroph adenomas and silent prolactinomas were similar to those in the corresponding functioning adenomas. In silent thyrotroph adenomas, both mRNAs showed high levels of expression that were similar to those in functioning and silent somatotroph adenomas. The results suggest that the cause of the silence in these tumors seems to be in the downstream to transcription of Pit-1 gene in the signaling pathway leading to hormone secretion. Competitive RT-PCR assay could distinguish silent adenomas of the Pit-1 group from the other nonfunctioning adenomas in the expression levels of Pit-1 and GHRH-R mRNAs. In the future, precise diagnosis of various adenomas may become possible by assaying transcription factors such as steroidogenic factor-1 and thyrotroph embryonic factor, which are thought to be related to adenohypophyseal cytodifferentiation.
Kobayashi
Ikuo
I
Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
Oka
Hidehiro
H
Naritaka
Heiji
H
Sato
Yuichi
Y
Fujii
Kiyotaka
K
Kameya
Toru
T
D000236:Adenoma / Q000145:classification / Q000175:diagnosis* / Q000378:metabolism* / Q000648:ultrastructure; D000328:Adult; D000368:Aged; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000378:metabolism* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000096:biosynthesis*; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D054339:Steroidogenic Factor 1; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000096:biosynthesis*
D004268:DNA-Binding Proteins; C515057:NR5A1 protein, human; C494187:POU1F1 protein, human; D012333:RNA, Messenger; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D054339:Steroidogenic Factor 1; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C048250:somatotropin releasing hormone receptor