Proopiomelanocortin, glucocorticoid, and CRH receptor expression in human ACTH-secreting pituitary adenomas

被引:0
作者
Maria Francesca Cassarino
Antonella Sesta
Luca Pagliardini
Marco Losa
Giovanni Lasio
Francesco Cavagnini
Francesca Pecori Giraldi
机构
[1] Istituto Auxologico Italiano IRCCS,Neuroendocrinology Research Laboratory
[2] Ospedale San Raffaele IRCCS,Department of Neurosurgery
[3] Istituto Clinico Humanitas,Department of Neurosurgery
[4] University of Milan,Department of Clinical Sciences and Community Health
来源
Endocrine | 2017年 / 55卷
关键词
Cushing’s disease; POMC; ACTH; CRH; Dexamethasone;
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中图分类号
学科分类号
摘要
ACTH-secreting pituitary tumors are by definition partially autonomous, i.e., secrete ACTH independent of physiological control. However, only few, small-sized studies on proopiomelanocortin (POMC) and its regulation by corticotropin-releasing hormone (CRH) or glucocorticoids are available. Objective of the present study was to report on constitutive and CRH- and dexamethasone-regulated POMC, CRH (CRH-R1), and glucocorticoid receptor (NR3C1) gene expression in a large series of human corticotrope adenomas. Fifty-three ACTH-secreting adenomas were incubated with 10 nM CRH or 10 nM dexamethasone for 24 h. POMC, CRH-R1,NR3C1, and its alpha and beta isoforms were quantified and medium ACTH measured. Constitutive POMC expression proved extremely variable, with macroadenomas exhibiting higher levels than microadenomas. POMC increased during CRH in most specimens; conversely, changes induced by dexamethasone were varied, ranging from decrease to paradoxical increase. No correlation between POMC and ACTH was detected in any experimental condition. CRH-R1 expression was not linked to the response to CRH while NR3C1 was expressed at greater levels in specimens who failed to inhibit during dexamethasone; glucocorticoid receptor α was the more abundant isoform and subject to down-regulation by dexamethasone. Our results demonstrate a considerable variability in POMC expression among tumors and no correlation between POMC and ACTH, suggesting that POMC peptide processing/transport plays a major role in modulating ACTH secretion. Further, CRH-R1 and NR3C1 expression were not linked to the expected ligand-induced outcome, indicating that receptor signaling rather than abundance determines corticotrope responses. Our findings pave the way to new avenues of research into Cushing’s disease pathophysiology.
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页码:853 / 860
页数:7
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