Dataset Information

Adrenal GIPR expression and chromosome 19q13 microduplications in GIP-dependent Cushing's syndrome.

ABSTRACT: GIP-dependent Cushing's syndrome is caused by ectopic expression of glucose-dependent insulinotropic polypeptide receptor (GIPR) in cortisol-producing adrenal adenomas or in bilateral macronodular adrenal hyperplasias. Molecular mechanisms leading to ectopic GIPR expression in adrenal tissue are not known. Here we performed molecular analyses on adrenocortical adenomas and bilateral macronodular adrenal hyperplasias obtained from 14 patients with GIP-dependent adrenal Cushing's syndrome and one patient with GIP-dependent aldosteronism. GIPR expression in all adenoma and hyperplasia samples occurred through transcriptional activation of a single allele of the GIPR gene. While no abnormality was detected in proximal GIPR promoter methylation, we identified somatic duplications in chromosome region 19q13.32 containing the GIPR locus in the adrenocortical lesions derived from 3 patients. In 2 adenoma samples, the duplicated 19q13.32 region was rearranged with other chromosome regions, whereas a single tissue sample with hyperplasia had a 19q duplication only. We demonstrated that juxtaposition with cis-acting regulatory sequences such as glucocorticoid response elements in the newly identified genomic environment drives abnormal expression of the translocated GIPR allele in adenoma cells. Altogether, our results provide insight into the molecular pathogenesis of GIP-dependent Cushing's syndrome, occurring through monoallelic transcriptional activation of GIPR driven in some adrenal lesions by structural variations.

SUBMITTER: Lecoq AL

PROVIDER: S-EPMC5621881 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Adrenal GIPR expression and chromosome 19q13 microduplications in GIP-dependent Cushing's syndrome.

Lecoq Anne-Lise AL Stratakis Constantine A CA Viengchareun Say S Chaligné Ronan R Tosca Lucie L Deméocq Vianney V Hage Mirella M Berthon Annabel A Faucz Fabio R FR Hanna Patrick P Boyer Hadrien-Gaël HG Servant Nicolas N Salenave Sylvie S Tachdjian Gérard G Adam Clovis C Benhamo Vanessa V Clauser Eric E Guiochon-Mantel Anne A Young Jacques J Lombès Marc M Bourdeau Isabelle I Maiter Dominique D Tabarin Antoine A Bertherat Jérôme J Lefebvre Hervé H de Herder Wouter W Louiset Estelle E Lacroix André A Chanson Philippe P Bouligand Jérôme J Kamenický Peter P

JCI insight 20170921 18

GIP-dependent Cushing's syndrome is caused by ectopic expression of glucose-dependent insulinotropic polypeptide receptor (GIPR) in cortisol-producing adrenal adenomas or in bilateral macronodular adrenal hyperplasias. Molecular mechanisms leading to ectopic GIPR expression in adrenal tissue are not known. Here we performed molecular analyses on adrenocortical adenomas and bilateral macronodular adrenal hyperplasias obtained from 14 patients with GIP-dependent adrenal Cushing's syndrome and one ...[more]

PMID: 28931750

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Project description:Abstract submitted to the Journal of clinical encodcrinology and metabolism: The molecular mechanisms responsible for the ectopic expression of the GIP receptor in the adrenal cortex of patients with GIP-dependent Cushing’s syndrome (CS) are unknown. Chronic adrenal stimulation by ACTH in Cushing’s disease (CD) or by GIP in GIP-dependent AIMAH both lead to induction of a set of genes which stimulate adrenal proliferation and steroidogenesis. The objective of this study was to compare the whole genome expression profile of adrenal glands of five cases of GIP-dependent bilateral macronodular adrenal hyperplasia with CS, one case of GIP-dependent adenoma, compared to five cases of ACTH-dependant hyperplasias (CD) and a pool of adrenals from 62 normal individuals. We used the genome-spanning Affymetrix U133 plus 2.0 microarray oligochips to identify genes differentially expressed specifically in GIP-dependent CS and which would be candidate genes implicated in the ectopic expression of the GIP receptor in the adrenal cortex. After data normalization and filtering, genes with differential expression were identified with a multi-step statistical analysis involving a student’s t-test, a filter on flags and a SAM analysis. A total of 721 probesets were thus isolated with intensity levels robustly related to the presence of a GIP-dependent hyperplasia. We performed a functional classification to further define potentially important biological processes and signaling mechanism for the formation of GIP-dependent AIMAH. Various probesets were related to metabolic processes, cell-surface and intracellular signaling, tumorigenesis, transport and transcription factors. The most relevant genes had their expression profile confirmed by real-time RT-PCR. This study reports an extensive series of potentially novel targets in the identification of the molecular mechanisms of ectopic expression of the GIP-receptor in this pathology. Keywords: Comparative genomic analysis

Project description:Previous studies have linked systemic glucocorticoid use with intestinal perforation. However, the association between intestinal perforation and endogenous hypercortisolism has not been well described, with only 14 previously published case reports. In this study, we investigated if intestinal perforation occurred more frequently in patients with ectopic ACTH syndrome and in those with a greater than 10-fold elevation of 24-hour urinary free cortisol level. Of 110 patients with ACTH-dependent Cushing's syndrome followed in two clinics in Canada, six cases with intestinal perforation were identified over 15 years. Age of patients ranged from 52 to 72, five females and one male, four with Cushing's disease and two with ectopic ACTH production, one from a pancreatic neuroendocrine tumor and one from medullary carcinoma of the thyroid. Five had diverticular perforation and one had intestinal perforation from a stercoral ulcer. All cases had their lower intestinal perforation when the cortisol production was high, and one patient had diverticular perforation 15 months prior to the diagnosis of Cushing's disease. As in previously reported cases, most had hypokalemia and abdominal pain with minimal or no peritoneal symptoms and this occurred during the active phase of Cushing's syndrome. Whereas all previously reported cases occurred in patients with 24-hour urinary free cortisol levels greater than 10-fold the upper limit of normal when measured and 11 of 14 patients had ectopic ACTH production, only one of our patients had this degree of hypercortisolism and four of our six patients had Cushing's disease. Similar to exogenous steroid use, patients with endogenous hypercortisolism also have a higher risk of intestinal, in particular diverticular, perforation and should be monitored closely for its occurrence with a low threshold for investigation and surgical intervention. Elective colonoscopy probably should be deferred until Cushing's syndrome is under control.

Dataset Information

Adrenal GIPR expression and chromosome 19q13 microduplications in GIP-dependent Cushing's syndrome.

Publications

Adrenal GIPR expression and chromosome 19q13 microduplications in GIP-dependent Cushing's syndrome.

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