title: Liver X receptor-α/β expression ratio is increased in ACTH-secreting pituitary adenomas.
abstract: The liver X receptors (LXR-α and -β) are nuclear oxysterol receptors that play pivotal roles in regulating the expression of genes involved in cholesterol transport and metabolism. Recently, several groups have reported that the LXRs also regulate adrenal steroidogenesis. In the previous report, we demonstrated that LXR-α is dominantly expressed in the pituitary and that LXR-α positively regulates the proopiomelanocortin (POMC) gene promoter at the transcriptional level. In this report, we evaluated the expression levels of LXR-α and -β gene in the human pituitary tumor. Even though LXR-α mRNA levels are not significantly increased in ACTH-secreting adenomas, LXR-α/β expression ratio is significantly higher than other pituitary tumors including normal pituitaries. Furthermore, in At-T20 cells, which express POMC gene, overexpression of LXR-β decreased POMC gene promoter activities. Thus, we concluded that LXR-α/β gene expression ratio is a critical factor to activate POMC gene expression in ACTH-secreting pituitary adenomas.
authors.affiliation: Department of Medicine and Molecular Science, Graduate School of Medicine, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8511, Gunma, Japan. khashi@med.gunma-u.ac.jp
authors.forename: Koshi
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Shunichi
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Emi
authors.initials: E
authors.lastname: Ishida
authors.forename: Atsuko
authors.initials: A
authors.lastname: Miura
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Horiguchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ozawa
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Shibusawa
authors.forename: Teturou
authors.initials: T
authors.lastname: Satoh
authors.forename: Masanobu
authors.initials: M
authors.lastname: Yamada
authors.forename: Shozo
authors.initials: S
authors.lastname: Yamada
authors.forename: Masatomo
authors.initials: M
authors.lastname: Mori
mesh_terms: D049913:ACTH-Secreting Pituitary Adenoma / Q000235:genetics / Q000378:metabolism*; D000236:Adenoma / Q000235:genetics / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000328:Adult; D005260:Female; D006801:Humans; D000071518:Liver X Receptors; D008297:Male; D008875:Middle Aged; D057093:Orphan Nuclear Receptors / Q000235:genetics / Q000378:metabolism*; D011333:Pro-Opiomelanocortin / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D000071518:Liver X Receptors; C000605213:NR1H3 protein, human; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone