Food-dependent Cushing's Syndrome Research Articles

From the First Case Reports to KDM1A Identification: 35 Years of Food (GIP)-Dependent Cushing's Syndrome.

Food-dependent Cushing's syndrome (FDCS) is a rare presentation of hypercortisolism from adrenal origin, mostly observed in primary bilateral macronodular adrenal hyperplasia (PBMAH) but also in some cases of unilateral adrenocortical adenoma. FDCS is mediated by the aberrant expression of glucose-dependent insulinotropic peptide (GIP) receptor (GIPR) in adrenocortical cells. GIP, secreted by duodenal K cells after food intake, binds to its ectopic adrenal receptor, and stimulates cortisol synthesis following meals. FDCS was first described more than 35 years ago, and its genetic cause in PBMAH has been recently elucidated: KDM1A inactivation by germline heterozygous pathogenic variants is constantly associated with a loss-of-heterozygosity of the short arm of chromosome 1, containing the KDM1A locus. This causes biallelic inactivation of KDM1A, resulting in the GIPR overexpression in the adrenal cortex. These new insights allow us to propose the KDM1A genetic screening to all PBMAH patients with signs of FDCS (low fasting cortisol that increases after a mixed meal or oral glucose load) and to all first-degree relatives of KDM1A variant carriers. Given that KDM1A is a tumor suppressor gene that has also been associated with monoclonal gammopathy of uncertain significance and multiple myeloma, the investigation of FDCS in the diagnostic management of patients with PBMAH and further genetic testing and screening for malignancies should be encouraged.

Bilateral Adrenocortical Nodular Disease and Cushing's Syndrome.

Primary Pigmented Nodular Adrenocortical Disease (PPNAD) and Bilateral Macronodular Adrenocortical Disease (BMAD) are two forms of Adrenocortical Nodular Diseases causing Cushing's syndrome, but are two very distinct conditions. PPNAD, affecting mostly young patients with an almost constant severe Cushing's syndrome, is characterized by pigmented micronodules, usually less than 1 cm, not always visible on imaging. On the contrary, BMAD is predominantly diagnosed in the fifth and sixth decades, with highly variable degrees of cortisol excess, from mild autonomous cortisol secretion to overt Cushing's syndrome. BMAD presents as large bilateral adrenal macronodules, easily observed on imaging. Both diseases are often genetically determined: frequently PPNAD is observed in a multiple neoplasia syndrome, Carney complex (CNC), and a germline genetic defect is identified in around 80% of index cases, always affecting key actors of the cAMP/PKA pathway: mostly PRKAR1A, encoding the PKA 1-alpha regulatory subunit. On the other hand, BMAD appears mostly isolated, and two predisposing genes are known at present: ARMC5, accounting for around 20% of index cases, and the recently identified KDM1A, causing the rare presentation with food-dependent Cushing's syndrome, mediated by the ectopic expression of the Glucose-dependent Insulinotropic Polypeptide receptor (GIPR) in adrenal nodules. GIPR was the first demonstrated receptor to illegitimately regulate cortisol secretion in nodular adrenocortical diseases, and a myriad of other receptors and paracrine signals were discovered afterward. The last 30 years were pivotal in the understanding of the genetics and pathophysiology of Bilateral Adrenocortical Nodular Diseases, leading to a personalized approach of these fascinating conditions.

OR08-01 Expression of Gonadal Differentiation Markers in Bilateral Macronodular Adrenocortical Disease

Abstract Disclosure: K. De Sousa: None. V. Pautasso: None. C. Duparc: None. S. Renouf: None. B. Ragazzon: None. F. Violon: None. L. Bouys: None. F. Bonnet-Serrano: None. M. Sibony: None. N. Driessens: None. S. Espiard: None. G. Raverot: None. J.Y. Bertherat: None. E. Louiset: None. H. Lefebvre: None. Context: Bilateral macronodular adrenocortical disease (BMAD) is a rare cause of primary Cushing syndrome, occurring mostly in women. ARMC5 and KDM1A mutations are responsible for distinct forms of BMAD. In particular, KDM1A mutations are associated with food-dependent Cushing syndrome. In addition, BMAD tissues can express illegitimate receptors, including LH receptor, that lead to aberrant control of cortisol secretion by various factors. Moreover, steroidogenic cells are able to abnormally produce bioactive factors, such as ACTH and the Leydig cell hormone INSL3. Since LH receptor, ACTH and INSL3 are known to be produced in gonads, we speculated on a gonadal-like differentiation of adrenocortical cells in BMAD tissues. Aim: The aim of our study was to investigate the presence of different gonadal markers in a series of BMAD tissues, and to search for secretion of adrenal and gonadal hormones by BMAD cells. Methodology: Gene expression of gonadal markers were evaluated by RNAseq. Immunohistochemical studies were performed on 41 BMAD and 9 normal adrenal samples to examine the presence of hormones (ACTH, INSL3, anti-Mullerian hormone [AMH]), the estrogen synthetizing enzyme aromatase, and transcription factors (GATA4, SOX9, FOXL2, MAGEA4) known to be expressed in testis or ovary. Perifusion experiments, coupled to immunoassays or liquid chromatography/mass spectrometry, were conducted to quantify hormone secretion by 2 adrenal explants. Results: BMAD tissues were collected from patients (60% women) without or with ARMC5 (32%) or KDM1A (13%) mutations. ARMC5-mutated tissues overexpressed FOXL2 and CYP19A1 (encoding aromatase) in comparison with other BMAD samples. In normal adrenals, cortisol-producing cells, located in the zona fasciculata, were immunonegative for INSL3, AMH, aromatase, GATA4 and SOX9, whereas FOXL2 and MAGEA4 immunostainings were detected in the cortex. In BMAH tissues, the presence of positive cells for ACTH (100% of BMAD), INSL3 (90%), AMH (50%), aromatase (77%), SOX9 (92%), GATA4 (97%), FOXL2 (100%) and MAGEA4 (100%) were observed in most of the samples regardless of the gender or mutational status. FOXL2 and MAGEA4 immunostainings were detected throughout BMAD tissues. Distribution of other gonadal markers was heterogenous in tissue sections with clusters of cells positive for ACTH, aromatase and GATA4 or ACTH and SOX9. Functional studies revealed pulsatile secretion of different glucocorticoids and INSL3 by BMAD explants. ACTH and hCG stimulated steroid production but were without effect on INSL3 release. Conclusion: These data show that steroidogenic cells in BMAD tissues exhibit a gonadal-type phenotype and abnormally secrete INSL3. They suggest that BMAD may result from a genetically driven defect occurring during early embryogenesis and affecting differentiation and development of adrenal tissues. Presentation: Friday, June 16, 2023

Food-dependent Cushing's syndrome due to unilateral adrenocortical adenoma with cortisol secretion without ACTH elevation detected in peripheral blood by the CRH test: a case report.

We report an extremely rare case of a 61-year old woman with food-dependent Cushing's syndrome (FDC) due to unilateral adrenocortical adenoma (UAA) with cortisol (CORT) secretion without ACTH elevation detected in peripheral blood by the CRH test. She was on oral medications for hypertension and depression, and presented weight gain, general fatigue, muscle weakness, and hypokalemia. Despite the fact that the diurnal variation of ACTH was always suppressed, a diurnal variation in CORT was observed, in the form of low levels in the early morning and high levels in the afternoon. An increase in CORT was shown in a 75 g-oral glucose tolerance test (OGTT) and in a mixed meal tolerance test, but no change in CORT levels was seen in intravenous glucose tolerance tests. Elevated CORT levels were observed in response to intravenous injection of CRH, although ACTH levels were always below the measured sensitivity. Laparoscopic left adrenalectomy was performed, which resulted in postoperative improvement in potassium and ACTH levels and disappearance of the CORT secretory response in the OGTT. Clear expression of glucose-dependent insulinotropic polypeptide receptor (GIPR), CRH and CRH receptor 2 (CRHR2) were confirmed in the surgically-resected UAA specimen by molecular and immunohistochemical analyses, suggesting the involvement of not only GIPR, but also CRH and CRHR2 in FDC.

OR04-3 Genetic Alterations of ARMC5 and KDM1A Are Associated With Different Expression Profiles of Illegitimate Receptors in Primary Bilateral Macronodular Adrenal Hyperplasia

Abstract Introduction Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH) is a heterogeneous disease characterized by bilateral adrenal macronodules responsible for adrenal Cushing. To date, two genetic causes of PBMAH are known: germline inactivating variants of the tumor suppressor genes ARMC5 identified in 2013 (Assié, N Eng J Med 2013), responsible for 20 to 25% of index cases, and KDM1A, identified recently (Vaczlavik, GIM 2021; Chasseloup, Lancet D&E 2021), responsible for the rare presentation associated with food-dependent Cushing's syndrome (FDCS) due to aberrant expression of the GIP receptor (GIPR) in adrenocortical cells. Multiple other illegitimate receptors are known to be responsible for abnormal cortisol response to various physiological stimuli in PBMAH. A recent multiomic analysis, identified three distinct molecular PBMAH groups: G1 with ARMC5-mutated tumors, G2 with KDM1A-mutated tumors from FDCS patients, and G3 with no identified genetic cause at present. We aimed to identify specific expression profiles of illegitimate receptors in the three groups. Methods Based on the transcriptome data obtained by RNA sequencing (Illumina) of the tumors from 31 patients (G1/ARMC5, 16 patients; G2/KDM1A, 6 patients; G3, 9 patients), expression of the following genes, encoding potential illegitimate receptors, were compared: ADRA1A, ADRA1B, ADRA1D, ADRA2A, ADRA2B, ADRA2C, ADRB1, ADRB2, ADRB3, AVPR1A, AVPR1B, AVPR2, GCGR, GIPR, HTR4, HTR7, LHCGR. Calculations were performed using R statistical software. The Bioconductor limma package was used to analyze mRNA differential expression. Results G1/ARMC5 tumors showed a relative overexpression of the vasopressin receptors AVPR1A and AVPR1B compared to the two other groups (fold-change [FC] =7.39, p<0.001 and 3.98, p<0.001, respectively) but a lower expression of AVPR2 (FC=0.43, p=0.015). G2/KDM1A tumors showed a dramatic overexpression of GIPR compared to the two other groups (FC=105.02, p<0.001) but also of the adrenergic receptors ADRA1D and ADRA2A (FC=2.93, p=0.027 and 9.99, p<0.001, respectively) and of the LH/hCG receptor (LHCGR) (FC=12.20, p<0.001). G3 tumors showed a slight overexpression of the adrenergic receptor ADRA1B (FC=3.49, p=0.001) and in few tumors ADRA1D, AVPR2 and LHCGR were highly expressed suggesting molecular heterogeneity in G3. Conclusion This study reveals specific expression profiles of illegitimate receptors related to the three molecular groups. ARMC5 tumors are associated with the overexpression of two vasopressin receptors, while, besides GIPR, KDM1A inactivation seems to drive the overexpression of the LH/hCG receptor, as previously suggested in patients with FDCS (Bertherat, JCE&M 2005), potentially responsible for Cushing's syndrome associated with pregnancy and menopause. These molecular patterns need to be corroborated by clinical data with a systematic testing of the aberrant cortisol responses. Additionally, further studies would be needed to investigate the clinical relevance and significance of moderate fold-changes in gene expression (e.g. <4). Presentation: Saturday, June 11, 2022 12:00 p.m. - 12:15 p.m.

Primary bilateral macronodular adrenal hyperplasia: definitely a genetic disease.

Primary bilateral macronodular adrenal hyperplasia (PBMAH) is an adrenal cause of Cushing syndrome. Nowadays, a PBMAH diagnosis is more frequent than previously, as a result of progress in the diagnostic methods for adrenal incidentalomas, which are widely available. Although some rare syndromic forms of PBMAH are known to be of genetic origin, non-syndromic forms of PBMAH have only been recognized as a genetic disease in the past 10 years. Genomics studies have highlighted the molecular heterogeneity of PBMAH and identified molecular subgroups, allowing improved understanding of the clinical heterogeneity of this disease. Furthermore, the generation of these subgroups permitted the identification of new genes responsible for PBMAH. Constitutive inactivating variants in ARMC5 and KDM1A are responsible for the development of distinct forms of PBMAH. To date, pathogenic variants of ARMC5 are responsible for 20-25% of PBMAH, whereas germline KDM1A alterations have been identified in >90% of PBMAH causing food-dependent Cushing syndrome. The identification of pathogenic variants in ARMC5 and KDM1A demonstrated that PBMAH, despite mostly being diagnosed in adults aged 45-60 years, is a genetic disorder. This Review summarizes the important progress made in the past 10 years in understanding the genetics of PBMAH, which have led to a better understanding of the pathophysiology, opening new clinical perspectives.

Integrated genomics reveals the molecular classification of Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH), correlating with specific profiles of illegitimate receptors expression and identifies KDM1A as the genetic cause of food-dependent Cushing syndrome

Integrated genomics reveals the molecular classification of Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH), correlating with specific profiles of illegitimate receptors expression and identifies KDM1A as the genetic cause of food-dependent Cushing syndrome

An Overview of the Heterogeneous Causes of Cushing Syndrome Resulting From Primary Macronodular Adrenal Hyperplasia (PMAH).

Primary macronodular adrenal hyperplasia (PMAH) is considered a rare cause of adrenal Cushing syndrome, is pituitary ACTH-independent, generally results from bilateral adrenal macronodules (>1 cm), and is often associated with variable cortisol secretion, resulting in a heterogeneous clinical presentation. Recent advances in the molecular pathogenesis of PMAH have offered new insights into the comprehension of this heterogeneous and complex adrenal disorder. Different molecular mechanisms involving the actors of the cAMP/protein kinase A pathway have been implicated in the development of PMAH, including germline and/or somatic molecular defects such as hyperexpression of the G-protein aberrant receptors and pathogenic variants of MC2R, GNAS, PRKAR1A, and PDE11A. Nevertheless, since 2013, the ARMC5 gene is believed to be a major genetic cause of PMAH, accounting for more than 80% of the familial forms of PMAH and 30% of apparently sporadic cases, except in food-dependent Cushing syndrome in which ARMC5 is not involved. Recently, 2 independent groups have identified that the tumor suppressor gene KDM1A is responsible for PMAH associated specifically with food-dependent Cushing syndrome. Consequently, PMAH has been more frequently genetically associated than previously assumed. This review summarizes the most important aspects, including hormone secretion, clinical presentation, radiological imaging, and molecular mechanisms, involved in familial Cushing syndrome associated with PMAH.

KDM1A inactivation causes hereditary food-dependent Cushing syndrome

PurposeThis study aimed to investigate the genetic cause of food-dependent Cushing syndrome (FDCS) observed in patients with primary bilateral macronodular adrenal hyperplasia (PBMAH) and adrenal ectopic expression of the glucose-dependent insulinotropic polypeptide receptor. Germline ARMC5 alterations have been reported in about 25% of PBMAH index cases but are absent in patients with FDCS. MethodsA multiomics analysis of PBMAH tissues from 36 patients treated by adrenalectomy was performed (RNA sequencing, single-nucleotide variant array, methylome, miRNome, exome sequencing). ResultsThe integrative analysis revealed 3 molecular groups with different clinical features, namely G1, comprising 16 patients with ARMC5 inactivating variants; G2, comprising 6 patients with FDCS with glucose-dependent insulinotropic polypeptide receptor ectopic expression; and G3, comprising 14 patients with a less severe phenotype. Exome sequencing revealed germline truncating variants of KDM1A in 5 G2 patients, constantly associated with a somatic loss of the KDM1A wild-type allele on 1p, leading to a loss of KDM1A expression both at messenger RNA and protein levels (P = 1.2 × 10–12 and P < .01, respectively). Subsequently, KDM1A pathogenic variants were identified in 4 of 4 additional index cases with FDCS. ConclusionKDM1A inactivation explains about 90% of FDCS PBMAH. Genetic screening for ARMC5 and KDM1A can now be offered for most PBMAH operated patients and their families, opening the way to earlier diagnosis and improved management.

The Glucose-Dependent Insulinotropic Polypeptide Receptor is Overexpressed Amongst GNAS1 Mutation-Negative Somatotropinomas and Drives Growth Hormone (GH)-Promoter Activity in GH3 Cells

Somatic mutations in the GNAS1 gene, encoding the α-subunit of the heterotrimeric stimulatory G protein (Gαs), occur in approximately 40% of growth hormone (GH)-secreting pituitary tumours. By altering the adenylate cyclase-cAMP-protein kinase A pathway, they unequivocally give somatotroph cells a growth advantage. Hence, the pathogenesis of somatotropinomas could be linked to anomalies in receptors coupled to the cAMP second-messenger cascade. Among them, the glucose-dependent insulinotropic polypeptide receptor (GIPR) is already known to play a primary role in the impaired cAMP-dependent cortisol secretion in patients affected by food-dependent Cushing's syndrome. In the present study, 43 somatotropinomas and 12 normal pituitary glands were investigated for GIPR expression by quantitative reverse transcriptase-polymerase chain reaction, western blotting and immunohistochemistry. Tumoural specimens were also evaluated for GNAS1 mutational status. The effect of GIPR overexpression on cAMP levels and GH transcription was evaluated in an in vitro model of somatotropinomas, the GH-secreting pituitary cell line GH3. GIPR was expressed at higher levels compared to normal pituitaries in 13 GNAS1 mutation-negative somatotropinomas. GIP stimulated adenylyl cyclase and GH-promoter activity in GIPR-transfected GH3 cells, confirming a correct coupling of GIPR to Gαs. In a proportion of acromegalic patients, GIPR overexpression appeared to be associated with a paradoxical increase in GH after an oral glucose tolerance test. Whether GIPR overexpression in acromegalic patients may be associated with this paradoxical response or more generally involved in the pathogenesis of acromegaly, as suggested by the mutually exclusive high GIPR levels and GNAS1 mutations, remains an open question.

Food-dependent Cushing's syndrome: from molecular characterization to therapeutical results

Cortisol secretion in ACTH-independent macronodular adrenal hyperplasia (AIMAH) may be regulated by the aberrant expression of several G-protein-coupled receptors. Bilateral adrenalectomy is the treatment of choice in most cases. We searched for aberrant receptor expression in a patient with AIMAH and evaluated the response to medical and surgical treatment. A 35-year-old woman with amenorrhea, hirsutism, and hypertension presented ACTH-independent cortisol secretion with high androgen levels. Abdominal computed tomography showed bilateral adrenal macronodules (4.5 cm right and 1.0 cm left). Scintigraphy with I(131)-norcholesterol showed bilateral uptake, prevalent on the right side. Several in vivo stimulation tests were assessed before and after treatment and in vitro studies were performed after unilateral adrenalectomy. Plasma cortisol increased after a standard meal test (60%) and oral glucose loading (147%), and the response was blunted by pretreatment with 100 microg s.c. octreotide. The therapy with long-acting release octreotide (octreotide-LAR) showed an improvement in urinary free cortisol (UFC) levels. Unilateral adrenalectomy was performed and histopathology revealed macronodular AIMAH. Cortisol and androgens increased after perifusion of tumoral tissue with glucose-dependent insulinotropic polypeptide (GIP), and GIP and LH-receptor overexpression was found in both the adrenal nodules and the adjacent cortex. After surgery, UFC and androgen levels normalized followed by clinical improvement. GIP and LH-receptor expression may coexist in AIMAH, influencing the functional and morphological phenotype. Aberrant hormone receptor expression enables specific pharmacological treatment, but long-term studies are needed to evaluate its real efficacy. Unilateral adrenalectomy may be a safe initial option, particularly for asymmetric bilateral adrenal enlargements.

The Aberrant Expression of the Gastric Inhibitory Polypeptide (GIP) Receptor in Adrenal Hyperplasia: Does Chronic Adrenocorticotropin Exposure Stimulate Up-Regulation of GIP Receptors in Cushing’s Disease?

Cortisol secretion is usually under the control of ACTH. However, cortisol secretion occurs in response to gastric inhibitory polypeptide (GIP) in rare cases of food-dependent Cushing's syndrome (CS). We have investigated whether chronic ACTH stimulation or activation of the ACTH signaling pathway might be associated with GIP receptor (GIPR) expression. RT-PCR analysis and primary culture of hyperplastic adrenals. All patients presented with CS: 20 unilateral adrenal adenomas, five Cushing's disease, one food-dependent CS. RT-PCR revealed GIPR expression in all hyperplastic adrenals studied. No RT-PCR product could be detected in two normal adrenals or 20 hyperfunctioning adrenal adenomas. Primary culture revealed a significant cAMP response to ACTH in all adrenals available for study (EC50, 8.1 x 10(-10) M in normals, 4.7 x 10(-10) M in Cushing's disease, and 4.4 x 10(-10) M in food-dependent disease). However, cultures taken from all four ACTH-dependent and the one food-dependent hyperplastic adrenals studied were also responsive to GIP (EC50 for cAMP, 1.3 x 10(-9) M in Cushing's disease and 4.1 x 10(-10) M in food-dependent disease). Fasting cortisol levels were low in the case of food-dependant Cushing's, rising postprandially as predicted. However, there was no trend toward low fasting or high postprandial cortisol in the other cases, suggesting that the presence of detectable GIPR alone, albeit with definite function in vitro, is not sufficient to cause clinically food-dependent CS. These data are consistent with the hypothesis that chronic ACTH stimulation or constitutive activation of the ACTH signaling pathway may be associated with aberrant GIPR expression, and suggest one mechanism for the pathogenesis of this phenomenon.

The ectopic expression of the gastric inhibitory polypeptide receptor is frequent in adrenocorticotropin-independent bilateral macronodular adrenal hyperplasia, but rare in unilateral tumors.

Control of cortisol secretion by the abnormal expression of the gastric inhibitory polypeptide receptor (GIP-R) have been observed in some rare cases of ACTH-independent, food-dependent Cushing's syndrome (FD-ACS) due to adrenal adenoma (AA) or bilateral macronodular hyperplasia (AIMAH). This study was performed to determine the prevalence of GIP-R ectopic expression in ACS and its correlation with fasting cortisol levels. GIP-R expression was studied by RT-PCR in 30 unilateral adrenal tumors [16 AA and 14 adrenocortical cancer (AC)] and 8 AIMAH tissues. Fasting and postprandial cortisol levels were assayed, respectively, at 0800 and 1200 h in AA, AC, and AIMAH, and 1 h after a morning standard meal in 6 AIMAH patients. Similar expression of 2 GIP-R isoforms was observed in 1 of 16 AA, 0 of 14 AC, and 4 of 8 AIMAH as well as in the 4 insulinomas used as positive controls. In vitro study of the GIP-R-expressing AA showed stimulation of cortisol secretion and cAMP production by GIP. The fasting 0800-h plasma cortisol level was above 276 nmol/liter in all patients except 1 AA case and 1 AIMAH case, both of whom expressed GIP-R. In the 3 additional AIMAH cases that expressed the GIP-R, fasting plasma cortisol levels were above 276 nmol/liter. This study demonstrates that ectopic expression of GIP-R is rare in AA and is usually associated with the low fasting plasma cortisol levels that characterize FD-ACS. In contrast, GIP-R expression is frequent in AIMAH and might not always be associated with a low fasting plasma cortisol level. This suggests that maintenance of hypercortisolemia in GIP-R- expressing AIMAH does not always depend solely on GIP-R, and that simultaneous abnormal expression of other membrane receptors might be present. The expression of GIP-R could not be observed during malignant transformation of the adrenal cortex. This study highlighted the major role of cAMP alterations secondary to GIP-R ectopic expression in the pathophysiology of AIMAH and in some rare cases of well differentiated benign adrenocortical tumors.

Food-Dependent Cushing's Syndrome: Possible Involvement of Leptin in Cortisol Hypersecretion

Food-Dependent Cushing's Syndrome: Possible Involvement of Leptin in Cortisol Hypersecretion

Food-dependent Cushing's syndrome: characterization and functional role of gastric inhibitory polypeptide receptor in the adrenals of three patients.

In the present work, the presence of gastric inhibitory polypeptide (GIP) receptors and their functional role in the adrenal cells of three patients with food-dependent Cushing's syndrome were studied. RT-PCR and in situ hybridization studies demonstrated the presence of GIP receptor in the adrenals of the three patients. The presence of this receptor was also demonstrated in two human fetal adrenals, but not in two normal adult human adrenals or in the adrenals of one patient with nonfood-dependent Cushing's syndrome. Freshly isolated cells from patient adrenals responded in a dose-dependent manner to the steroidogenic action of both ACTH and GIP, whereas cells from normal adrenals responded only to ACTH. Treatment of cultured normal adrenal cells with ACTH, but not with GIP, increased the messenger ribonucleic acid (mRNA) levels of cholesterol side-chain cleavage cytochrome P-450, P450c17, and 3beta-hydroxysteroid dehydrogenase, whereas both hormones enhanced these mRNAs in patients' adrenal cells, although the effects of ACTH were greater than those of GIP. Moreover, pretreatment with ACTH enhanced the steroidogenic responsiveness of both normal and patient adrenal cells, whereas GIP caused homologous desensitization, and this was associated with a marked reduction of GIP receptor mRNA levels, as demonstrated by RT-PCR and in situ hybridization. Finally, both ACTH and GIP inhibited DNA synthesis in one patient's adrenal cells, whereas in normal adrenal cells only ACTH had this effect. In conclusion, the present data demonstrate that ectopic expression of functional GIP receptors is the main cause of food-dependent Cushing's syndrome.

Food-Dependent Cushing's Syndrome: Characterization and Functional Role of Gastric Inhibitory Polypeptide Receptor in the Adrenals of Three Patients

Food-Dependent Cushing's Syndrome: Characterization and Functional Role of Gastric Inhibitory Polypeptide Receptor in the Adrenals of Three Patients

Adrenocortical overexpression of gastric inhibitory polypeptide receptor underlies food-dependent Cushing's syndrome.

Abnormal responsiveness of adrenocortical cells to gastric inhibitory polypeptide (GIP) in food-dependent Cushing's syndrome suggested that adrenal expression of ectopic, overexpressed, or mutated GIP receptor (GIPR) underlies this syndrome. The expression of GIPR was studied by RT-PCR in human adrenal tissues from two patients with GIP-dependent Cushing's syndrome (adenoma, bilateral hyperplasia), five fetal or adult controls, one patient with Cushing's disease, and four patients with non-food-dependent cortisol-secreting adenomas or bilateral hyperplasias and compared to that in normal pancreas. Hybridization of the RT-PCR-amplified ribonucleic acids with the human GIPR complementary DNA showed an overexpression of GIPR in the adrenals of the two GIP-dependent Cushing's syndrome patients compared to that in normal adrenal tissues (2-3 orders of magnitude) or pancreas (10-fold); no signal could be seen in adrenal adenomas or macronodular hyperplasia from cases of non-food-dependent Cushing's syndrome. No mutation of the GIPR was identified by sequencing the full-length receptor in GIP-dependent adrenal tissue. New alternative spliced isoforms of the GIPR were found, but are identical in GIP-dependent and normal adrenal tissues. Incubation of adrenal cells with GIP stimulates cortisol secretion in GIP-dependent, but not in normal fetal, adult, or non-food-dependent Cushing's syndrome, adrenals. We conclude that the GIPR overexpression and its coupling to steroidogenesis underlie GIP-dependent Cushing's syndrome.

Gastric inhibitory polypeptide (GIP) stimulates cortisol secretion, cAMP production and DNA synthesis in an adrenal adenoma responsible for food-dependent cushing's syndrome.

We studied in vitro an adrenal tumor responsible for food-dependent, ACTH independent, Cushing's's syndrome. Cortisol secretion by isolated tumor cells was stimulated by GIP and ACTH, but not by the gut hormone glucagon-like peptide-1 (GLP-1). Both GIP and ACTH stimulated production of cAMP but not inositol 1,4,5-trisphosphate IP3). In quiescent tumor cells, GIP and ACTH stimulated [3H]-thymidine incorporation and p42-p44 MAP kinase activity. In normal human adrenocortical cells cortisol secretion and [3H]-thymidine incorporation were stimulated by ACTH but not by GIP. GIP receptor mRNA, assessed by RT-PCR, was highly expressed in the tumor, but undetectable in the adjacent hypotrophic adrenal tissue, in a normal adrenal, in two adrenal tumors responsible for food-independent Cushing's syndrome and in two hyperplastic adrenals associated with ACTH hypersecretion. Low levels of ACTH receptor mRNA were also detectable in the tumor. We conclude that abnormal expression of the GIP receptor allows adrenocortical cells to respond to food intake with an increase of cAMP that may participate in stimulation of both cortisol secretion and proliferation of the tumor cells.

Food-dependent Cushing's syndrome resulting from abundant expression of gastric inhibitory polypeptide receptors in adrenal adenoma cells

Food-dependent Cushing's syndrome resulting from abundant expression of gastric inhibitory polypeptide receptors in adrenal adenoma cells

Food-dependent Cushing syndrome: a new entity of organic hypercorticism

Diagnosis of Cushing's syndrome is quite difficult in endocrinology. Spontaneous Cushing's syndrome is usually divided into two subgroups, one which is dependent on corticotropin (ACTH) and another one which is not. In the first class are Cushing's disease, the ectopic corticotropin syndrome and the rare ectopic corticotropin-releasing hormone (CRH) syndrome; these ACTH-dependent Cushing's syndrome have usually diffusely enlarged adrenal glands. In the second class are cortisol producing unilateral adrenocortical adenomas or carcinomas, and the recent Cushing's syndrome with food dependent periodic hormonogenesis. This food dependent Cushing's syndrome is an ACTH-independent Cushing's syndrome with multinodular enlargement of both adrenal glands. Pathogenesis is an aberrant adrenal sensitivity to physiologic secretion of gastric inhibitory peptide (GIP). Ectopic expression of GIP receptors on adrenal cells involve pathologic food induced cortisol secretion. Food dependent Cushing's syndrome is a new cause of Cushing's syndrome. Food induced cortisol secretion may have to be explored in the ACTH-independent Cushing's syndrome.