Multiple aberrant hormone receptors in Cushing's syndrome

Cushing's syndrome diagnosed incidentally on CT imaging

In this case report, we describe an uncommon presentation of Cushing's syndrome in a patient in their 60s who presented to the emergency department with left-sided chest pain. The initial workup for the patient was unremarkable except for an elevated blood pressure and elevated fasting plasma glucose. A CT scan of the chest, abdomen and pelvis was performed, demonstrating a splenic artery thrombus with multiple splenic infarcts, in addition to a combination of macronodular adrenal hyperplasia, bilateral gynecomastia, centripetal fat distribution and suspected mild bone demineralisation. Adrenocorticotropic hormone-independent macronodular adrenal hyperplasia, a rare aetiology responsible for Cushing's syndrome, was raised as a potential unifying diagnosis for the patient's hypercoagulable status, which was subsequently confirmed on an endocrinological investigation. The case report underscores the importance of communicating clinically relevant details to the imaging specialist in combination with considering a broad differential, including endocrine disorders, when evaluating an undifferentiated patient with atypical imaging findings.

Primary bilateral macronodular adrenal hyperplasia: A series of 32 cases and literature review

Primary bilateral macronodular adrenal hyperplasia (PBMAH) accounts for <2% of cases of Cushing's syndrome. The majority of patients present with no obvious steroid excess it means with autonomous cortisol secretion (ACS). The classic treatment for patients with overt Cushing's syndrome is bilateral adrenalectomy, but unilateral resection of the larger adrenal gland can result in clinical and/or biochemical remission in >90% of cases, especially in cases of ACS. In this article, a series of 32 cases with PBMAH is described. Most of the cases of PBMAH had ACS, except for one case with overt Cushing's syndrome. A study of aberrant receptors was performed in six patients, being negative in three cases, positive in the metoclopramide test in two cases and positive in the metoclopramide test and in the mixed meal test in another patient. The patient with overt Cushing's syndrome was treated with adrenostatic therapy achieving biochemical control, while two patients with ACS underwent unilateral adrenalectomy with resection of the largest adrenal gland, demonstrating hypercortisolism remission and improvement of cardiovascular risk factors after surgery. This article describes a series of 32 cases of PBMAH and offers a comprehensive review of PBMAH.

The effect of unilateral adrenalectomy on patients with primary bilateral macronodular adrenal hyperplasia

PURPOSE

To evaluate the long-term effect of unilateral adrenalectomy (uADX) on patients with primary bilateral macronodular adrenal hyperplasia (PBMAH).

METHODS

We retrospectively reviewed 29 patients (including 11 men and 18 women) with PBMAH and Cushing's syndrome (CS) between 2005 and 2019 who underwent uADX in our center. Clinical symptoms, serum cortisol (8:00 a.m., 4:00 p.m., and 0:00 a.m.), 24 h urinary free cortisol (UFC), computed tomography (CT) scan of the adrenal gland, and pituitary nuclear magnetic resonance (MR) scan performed before and after operation were analyzed.

RESULTS

The median follow-up time was 39 (13-134) months. uADX decreased significantly at 24 h UFC (median: 357.14 vs. 89.50 ug/24 h, P < 0.001) and serum cortisol (8:00 a.m.) (median: 22.88 vs. 12.50 ug/uL, P < 0.001) 1 year after surgery. In total, 17 of 29 patients had normal UFC again 1 year after surgery, while one of them suffered a relapse after 61 months. However, uADX failed to decrease UFC to the normal range in the other patients. Ten of the remaining 12 uncured patients and the relapsed patient finally underwent contralateral adrenalectomy (cADX). The 24 h UFC of the patients who were cured (n = 17) after uADX was significantly lower than that of the uncured patients (n = 12) (222.30 vs. 579.10 ug/24 h, P = 0.011).

CONCLUSION

uADX may be an appropriate treatment for patients with mildly elevated cortisol, while contralateral adrenalectomy (cADX) may be required for patients with highly elevated cortisol. The level of 24 h UFC is helpful to predict patients' prognosis.

Gene Mutations in Cushing's Syndrome

Background

Prolonged exposure to glucocorticoids can result in the development of Cushing's syndrome. Excess serum cortisol can occur due to several factors including exogenous steroids, pituitary and adrenal adenoma, and ectopic ACTH secretion.

Summary

The last 2 decades have seen significant progress in identifying new genetic and molecular mechanisms underlying hypercortisolemia. This has implicated mutations seen in a multitude of aberrant pathways that underpin the pathophysiology of Cushing's syndrome.

Key Messages

There is much overlap between the different, with mutations affecting well-understood molecular pathways such as the cAMP/PKA/MAPK and Wnt signalling systems. Further work should delineate the exact involvement of specific mutations in Cushing's syndrome and the effect of epigenetic/microenvironmental interactions. This could have implications for screening, as the identification of specific mutations may lead to earlier identification and subsequently improved prognosis.

Systematic analysis of the BET family in adrenocortical carcinoma: The expression, prognosis, gene regulation network, and regulation targets

BACKGROUND

Bromodomain and extracellular terminal (BET) family (including BRD2, BRD3, and BRD4) is considered to be a major driver of cancer cell growth and a new target for cancer therapy. Currently, more than 30 targeted inhibitors have shown significant inhibitory effects against various tumors in preclinical and clinical trials. However, the expression levels, gene regulatory networks, prognostic value, and target prediction of BRD2, BRD3, and BRD4 in adrenocortical carcinoma (ACC) have not been fully elucidated. Therefore, this study aimed to systematically analyze the expression, gene regulatory network, prognostic value, and target prediction of BRD2, BRD3, and BRD4 in patients with ACC, and elucidated the association between BET family expression and ACC. We also provided useful information on BRD2, BRD3, and BRD4 and potential new targets for the clinical treatment of ACC.

METHODS

We systematically analyzed the expression, prognosis, gene regulatory network, and regulatory targets of BRD2, BRD3, and BRD4 in ACC using multiple online databases, including cBioPortal, TRRUST, GeneMANIA, GEPIA, Metascape, UALCAN, LinkedOmics, and TIMER.

RESULTS

The expression levels of BRD3 and BRD4 were significantly upregulated in ACC patients at different cancer stages. Moreover, the expression of BRD4 was significantly correlated with the pathological stage of ACC. ACC patients with low BRD2, BRD3, and BRD4 expressions had longer survival than patients with high BRD2, BRD3, and BRD4 expressions. The expression of BRD2, BRD3, and BRD4 was altered by 5%, 5%, and 12% in 75 ACC patients, respectively. The frequency of gene alterations in the 50 most frequently altered BRD2, BRD3, and BRD4 neighboring genes in these ACC patients were ≥25.00%, ≥25.00%, and ≥44.44%, respectively. BRD2, BRD3, and BRD4 and their neighboring genes form a complex network of interactions mainly through co-expression, physical interactions, and shared protein domains. Molecular functions related to BRD2, BRD3, and BRD4 and their neighboring genes mainly include protein-macromolecule adaptor activity, cell adhesion molecule binding, and aromatase activity. Chemokine signaling pathway, thiamine metabolism, and olfactory transduction were found to be enriched as per the KEGG pathway analysis. SP1, NPM1, STAT3, and TP53 are key transcription factors for BRD2, BRD4, and their neighboring genes. MiR-142-3P, miR-484, and miR-519C were the main miRNA targets of BRD2, BRD3, BRD4, and their neighboring genes. We analyzed the mRNA sequencing data from 79 patients with ACC and found that ZSCAN12, DHX16, PRPF4B, EHMT1, CDK5RAP2, POMT1, WIZ, ZNF543, and AKAP8 were the top nine genes whose expression were positively associated with BRD2, BRD3, and BRD4 expression. The expression level of BRD2, BRD3, and BRD4 positively correlated with B cell and dendritic cell infiltration levels. BRD4-targeted drug PFI-1 and (BRD2, BRD3, and BRD4)-targeted drug I-BET-151 may have good inhibitory effects on the SW13 cell line.

CONCLUSIONS

The findings of this study provide a partial basis for the role of BRD2, BRD3, and BRD4 in the occurrence and development of ACC. In addition, this study also provides new potential therapeutic targets for ACC, which can serve as a reference for future basic and clinical research.

Clinical, pathophysiologic, genetic and therapeutic progress in Primary Bilateral Macronodular Adrenal Hyperplasia

Patients with primary bilateral macronodular adrenal hyperplasia (PBMAH) usually present bilateral benign adrenocortical macronodules at imaging and variable levels of cortisol excess. PBMAH is a rare cause of primary overt Cushing's syndrome, but may represent up to one third of bilateral adrenal incidentalomas with evidence of cortisol excess. The increased steroidogenesis in PBMAH is often regulated by various G-protein coupled receptors aberrantly expressed in PBMAH tissues; some receptor ligands are ectopically produced in PBMAH tissues creating aberrant autocrine/paracrine regulation of steroidogenesis. The bilateral nature of PBMAH and familial aggregation, led to the identification of germline heterozygous inactivating mutations of the ARMC5 gene, in 20-25% of the apparent sporadic cases and more frequently in familial cases; ARMC5 mutations/pathogenic variants can be associated with meningiomas. More recently, combined germline mutations/pathogenic variants and somatic events inactivating the KDM1A gene were specifically identified in patients affected by GIP-dependent PBMAH. Functional studies demonstrated that inactivation of KDM1A leads to GIP-receptor (GIPR) overexpression and over or down-regulation of other GPCRs. Genetic analysis is now available for early detection of family members of index cases with PBMAH carrying identified germline pathogenic variants. Detailed biochemical, imaging, and co-morbidities assessment of the nature and severity of PBMAH is essential for its management. Treatment is reserved for patients with overt or mild cortisol/aldosterone or other steroid excesses taking in account co-morbidities. It previously relied on bilateral adrenalectomy; however recent studies tend to favor unilateral adrenalectomy, or less frequently, medical treatment with cortisol synthesis inhibitors or specific blockers of aberrant GPCR.

Treatment of Primary Pigmented Nodular Adrenocortical Disease

Primary pigmented nodular adrenocortical disease (PPNAD) is a rare cause of adrenocorticotropin hormone (ACTH)-independent Cushing's syndrome (CS), which mainly occurs in children and young adults. Treatment options with proven clinical efficacy for PPNAD include adrenalectomy (bilateral or unilateral adrenalectomy) and drug treatment to control hypercortisolemia. Previously, the main treatment of PPNAD is bilateral adrenal resection and long-term hormone replacement after surgery. In recent years, cases reports suggest that unilateral or subtotal adrenal resection can also lead to long-term remission in some patients without the need for long-term hormone replacement therapy. Medications for hypercortisolemia, such as Ketoconazole, Metyrapone and Mitotane et.al, have been reported as a preoperative transition for in some patients with severe hypercortisolism. In addition, tryptophan hydroxylase inhibitor, COX2 inhibitor Celecoxib, somatostatin and other drugs targeting the possible pathogenic mechanisms of the disease are under study, which are expected to be applied to the clinical treatment of PPNAD in the future. In this review, we summarize the recent progress on treatment of PPNAD, in which options of surgical methods, research results of drugs acting on possible pathogenic mechanisms, and the management during gestation are described in order to provide new ideas for clinical treatment.

Usefulness of 68 Ga-Pentixafor PET/CT on Diagnosis and Management of Cushing Syndrome

PURPOSE

This pilot study investigated the performance of C-X-C motif chemokine receptor 4 (CXCR4) molecular imaging ( 68 Ga-pentixafor PET/CT) in Cushing syndrome (CS) and the correlation between CXCR4 signaling interactions and glucose metabolism in adrenocorticotropin-cortisol pathway.

METHODS

We retrospectively evaluated 31 patients (16 patients with CS and 15 patients with nonfunctioning pituitary or adrenal adenomas). All patients underwent 68 Ga-pentixafor PET/CT, and 11 with pituitary adenoma also underwent 18 F-FDG PET/CT. The diagnosis accuracy of 68 Ga-pentixafor PET/CT was calculated. The correlation between radiouptake along the pituitary-adrenal axis and hormone levels was calculated.

RESULTS

Patients with Cushing disease characterized a focal uptake in adrenocorticotropic hormone-producing pituitary adenoma (ACTH-PA). In ACTH-independent CS, there was increased uptake of 68 Ga-pentixafor in adrenal lesions but not in the pituitary fossa. The nonfunctioning pituitary or adrenal adenomas showed negative 68 Ga-pentixafor signal. The one patient with metastatic ectopic ACTH syndrome had multiple 68 Ga-pentixafor-avid lesions. Using the threshold of SUV max >8.5 in the adrenal lesions, the sensitivity and specificity of 68 Ga-pentixafor PET/CT to diagnose cortisol-producing adenoma were 100% and 84.9%. A cutoff SUV max value of 3.0 on 68 Ga-pentixafor PET/CT had 100% sensitivity and specificity for differentiating ACTH-PA. The corresponding hormone level was significantly correlated with uptake of 68 Ga-pentixafor in pituitary adenoma and adrenal tissue but not with glucose metabolism.

CONCLUSION

We have characterized the performance of 68 Ga-pentixafor in different subtypes of CS. 68 Ga-pentixafor PET/CT is promising in the differential diagnosis of both ACTH-independent and ACTH-dependent CS. Activated CXCR4 molecular signaling along the pituitary-adrenal axis was found in patients with Cushing disease.

Current approach of primary bilateral adrenal hyperplasia

PURPOSE OF REVIEW

To discuss the most recent findings on the pathophysiology, the genetic and molecular causes of primary bilateral adrenal hyperplasia (PBAH). The diagnostic approach of patients with PBAH will also be presented in detail with an emphasis on the emerging diagnostic tools and finally, the treatment of PBAH will be discussed with an emphasis on the newest surgical and medical treatment approaches.

RECENT FINDINGS

PBAH is a highly heterogeneous condition mostly detected incidentally on abdominal imaging. Based on the size of the nodules, PBAH is subdivided into primary bilateral macronodular adrenal hyperplasia (PBMAH) and micronodular adrenal hyperplasia. A substantial proportion of patients with PBMAH harbor a germline mutation of the armadillo repeat containing 5 tumor suppression gene and therefore genetic testing is strongly recommended. Measurements of plasma or urinary multisteroid profiles show promising results in that PBMAH has a distinctive plasma steroid fingerprint that can help in diagnosis and subtyping of PBMAH. Finally, although surgery is the mainstay of treatment of patients with PBAH, medical therapy is increasingly emerging as an alternative option.

SUMMARY

PBAH is a poorly studied and therefore a challenging disease to diagnose and treat. Hopefully with these newest diagnostic and therapeutic tools, a more comprehensive approach will be adopted.

Prevalence and phenotype of primary bilateral macronodular adrenal hyperplasia with autonomous cortisol secretion: a study of 98 patients

AIM

This study evaluated prevalence of primary bilateral macronodular adrenal hyperplasia (PBMAH). It also analyzed the differential phenotype of patients with PBMAH compared to other bilateral adrenal lesions that do not meet the definition of PBMAH.

METHODS

We reviewed the medical records of 732 patients diagnosed with an adrenal incidentaloma at our center. Ninety-eight patients with subclinical hypercortisolism were included in the analysis. We defined PBMAH as the presence of plasma cortisol > 1.8 μg/dL after an over-night 1-mg dexamethasone test, bilateral adrenal hyperplasia, and bilateral adrenal nodules > 1 cm.

RESULTS

A total of 31 patients had PBMAH. Patients with PBMAH showed greater prevalence of autonomous cortisol secretion (plasma cortisol > 5.0 μg/dL after an overnight 1-mg dexamethasone test) than patients without PBMAH (OR 4.1, 95%CI 1.38-12.09, p = 0.010). Tumor size and total adenomatous mass were significantly greater in patients with PBMAH compared to patients without PBMAH (30.2 ± 12.16 vs. 24.3 ± 8.47 mm, p = 0.010 and 53.9 ± 20.8 vs. 43.3 ± 14.62 mm, p = 0.023), respectively. A greater proportion of patients with PBMAH had diabetes compared to patients without PBMAH (45.2% vs. 25.4%, p = 0.05).

CONCLUSION

PBMAH is present in one-third of patients with adrenal incidentaloma and subclinical hypercortisolism. Patients with PBMAH showed greater autonomous cortisol secretion, bigger tumor size, and higher rates of diabetes than those without PBMAH.

A 30-year single-center experience of unilateral adrenalectomy for primary bilateral macronodular adrenal hyperplasia

OBJECTIVE

The aim of this study is to assess the short- and long-term outcomes of unilateral adrenalectomy (UA) in patients with primary bilateral macronodular adrenal hyperplasia (PBMAH).

METHODS

We conducted a retrospective study of 124 patients with PBMAH who underwent UA.

RESULTS

124 adrenalectomies were performed without intraoperative mortality. After a median duration of 28.5months (1∼165months, mean 51.92 ± 47.21 months), 116 patients were available for follow-up. Cushingoid features remitted in 70.8% (43/65) of patients with overt Cushing's Syndrome (CS). Hypertension and diabetes mellitus improved in 82.3% (79/96) and 69.0% (29/42) of patients respectively. 6.0% (7/116) of patients developed glucocorticoid insufficiency postoperatively, and all resolved during the follow-up. The mean 24h-UFC (reference range 12.3∼103.5μg/24h) decreased gradually from 456.02±422.33μg/24hr at baseline to 84.47±70.06μg/24hr within 3 months and then climbed progressively in some patients. 55.2% (64/116) had biochemical recurrence with/without symptom recurrence and 67.2% (43/64) of them received contralateral adrenalectomy. The median interval time of the second operation from the first UA was 24 months (1∼165months, mean 43.58 ± 44.54 months), and it took less time in patients with overt CS (median 22 months, 1∼165 months, mean 37.24 ± 41.85 months) than those without overt CS (median 72 months, 1∼144 months, mean 61.45 ± 46.73 months). Patients with overt CS had larger surgical-side or contralateral adrenal volume than that of patients without overt CS. Patients with contralateral adrenal volume larger than 33.54ml or with pre-operative UFC more than 216.08μg/24hr were more likely to have recurrence.

CONCLUSION

The efficiency of UA is transient for majority of patients, and the indications should be strictly limited to those with subclinical or milder CS. The successful UA patients still require close lifetime follow-up for recurrence of hypercortisolism.

Cushing´s syndrome due to bilateral adrenal cortical disease: Bilateral macronodular adrenal cortical disease and bilateral micronodular adrenal cortical disease

Cushing´s syndrome (CS) secondary to bilateral adrenal cortical disease may be caused by bilateral macronodular adrenal cortical disease (BMACD) or by bilateral micronodular adrenal cortical disease (miBACD). The size of adrenal nodules is a key factor for the differentiation between these two entities (>1cm, BMACD and <1cm; miBACD). BMACD can be associated with overt CS, but more commonly it presents with autonomous cortisol secretion (ACS). Surgical treatment of BMACD presenting with CS or with ACS and associated cardiometabolic comorbidities should be the resection of the largest adrenal gland, since it leads to hypercortisolism remission in up to 95% of the cases. Medical treatment focused on the blockade of aberrant receptors may lead to hypercortisolism control, although cortisol response is frequently transient. miBACD is mainly divided in primary pigmented nodular adrenocortical disease (PPNAD) and isolated micronodular adrenocortical disease (i-MAD). miBACD can present at an early age, representing one of the main causes of CS at a young age. The high-dose dexamethasone suppression test can be useful in identifying a paradoxical increase in 24h-urinary free cortisol, that is a quite specific in PPNAD. Bilateral adrenalectomy is generally the treatment of choice in patients with overt CS in miBACD, but unilateral adrenalectomy could be considered in cases with asymmetric disease and mild hypercortisolism. This article will discuss the clinical presentation, genetic background, hormonal and imaging features and treatment of the main causes of primary bilateral adrenal hyperplasia associated with hypercortisolism.

Bilateral Adrenal Hyperplasia: Pathogenesis and Treatment

Bilateral adrenal hyperplasia is a rare cause of Cushing’s syndrome. Micronodular adrenal hyperplasia, including the primary pigmented micronodular adrenal dysplasia (PPNAD) and the isolated micronodular adrenal hyperplasia (iMAD), can be distinguished from the primary bilateral macronodular adrenal hyperplasia (PBMAH) according to the size of the nodules. They both lead to overt or subclinical CS. In the latter case, PPNAD is usually diagnosed after a systematic screening in patients presenting with Carney complex, while for PBMAH, the diagnosis is often incidental on imaging. Identification of causal genes and genetic counseling also help in the diagnoses. This review discusses the last decades’ findings on genetic and molecular causes of bilateral adrenal hyperplasia, including the several mechanisms altering the PKA pathway, the recent discovery of ARMC5, and the role of the adrenal paracrine regulation. Finally, the treatment of bilateral adrenal hyperplasia will be discussed, focusing on current data on unilateral adrenalectomy.

A case of adrenocortical adenoma harboring venous thrombus mimicking adrenal malignancy

Advances in imaging technology and its widespread use have increased the number of identified patients with bilateral adrenal incidentalomas. The pathology of bilateral adrenal incidentalomas is gradually elucidated by its increased frequency. Although there is no consensus regarding the optimal management of bilateral adrenal lesions, adrenal lesions that are a suspected adrenocortical carcinoma on the basis of radiological imaging require surgical resection. We report a clinically interesting case of a 59-year-old female with adrenocortical adenoma harboring venous thrombus that mimicked adrenal malignancy. She was referred for evaluation of asymptomatic asymmetric lesions on both adrenal glands. Abdominal computed tomography and magnetic resonance imaging showed a 4.7-cm-diameter heterogenous lesion with peripheral enhancement in the right adrenal gland and a 2.0-cm-diameter homogenous lesion in the left adrenal gland. Adrenal scintigraphy with ¹³¹I-adosterol exhibited marked accumulation in the left lesion and slight accumulation in the middle inferior portion of the right lesion. Endocrine data revealed subclinical Cushing syndrome, and the patient underwent right laparoscopic adrenalectomy. The serum cortisol level was not suppressed on an overnight dexamethasone suppression test after the adrenalectomy. The resected tumor revealed a cortisol-producing adrenocortical adenoma harboring an organized and re-canalized venous thrombus, which was associated with focal papillary endothelial hyperplasia. This case illustrates the difficulty with preoperatively diagnosing this heterogeneously enhanced large benign adrenal lesion and differentiating it from adrenocortical carcinoma or angiosarcoma.

Functional characterization of adrenocortical masses in nononcological patients using [68Ga]-pentixafor

Purpose: We aimed to investigate the diagnostic and prognostic value of ⁶⁸Ga-pentixafor positron emission tomography (PET)/computed tomography (CT) imaging in non-cancer patients with suspected adrenal masses. Methods: Sixty-four patients who had benign adrenal masses on CT were retrospectively included in our study. All patients underwent ⁶⁸Ga-pentixafor PET/CT scans, and 56 of these patients subsequently underwent adrenalectomy. The subtypes of 81 adrenal tumors including 14 nonfunctioning adrenal nodules, 4 cortisol-producing adenomas, 41 aldosterone-producing adenomas, 5 suspected unilateral adrenal hyperplasia, 15 idiopathic aldosterone hyperplasia and 2 pheochromocytomas, were determined by histology or follow-up evaluations. The functional lateralization diagnosis efficiency was calculated by visual analysis. Semi-quantitative parameters of these lesions including maximum standardized uptake value (SUV_max), the ratio of lesional SUV_max to normal liver SUVmean (LLR), and the ratio of lesional SUV_max to contralateral adrenal tissue SUVmean (LCR) have also been calculated. Dynamic analysis has also been performed on fifteen patients. Besides, clinical outcomes were assessed and compared in patients who underwent adrenalectomy. Results: The sensitivity and specificity of ⁶⁸Ga-pentixafor PET for functional lateralization of patients with adrenocortical lesions were 97.8% (45/46) and 87.5% (14/16) respectively. The two pheochromocytoma lesions had lower pentixafor uptake compared to the normal adrenal glands. Functioning (active) adrenocortical adenomas showed an elevated SUV_max of 16.3±7.9 in comparison to 4.4±1.7 in nonfunctioning (inactive) adenomas and 5.5±2.7 in hyperplasia lesions (P<0.0001). To identify active adrenocortical adenomas, a cutoff value of 7.1 for SUV_max showed a sensitivity of 90.9% and a specificity of 85.3% (AUC=0.96, P<0.0001); a cutoff value of 2.5 for LLR showed a sensitivity of 95.5% and a specificity of 88.2% (AUC=0.97, P<0.0001); and a cutoff value of 2.4 for LCR showed a sensitivity of 88.6% and a specificity of 91.8% (AUC=0.95, P<0.0001). The graphical Ki of active adrenocortical adenomas was significantly higher than in-active adenomas. Uptake values for ⁶⁸Ga-pentixafor were significantly higher in patients with preferable outcomes (cured/improved) (SUV_max=15.5±8.0, LLR=6.5±4.3, LCR=6.2±5.0) than in patients with nonpreferable outcomes (no improvement) (SUV_max=4.2±0.5, LLR=1.3±0.2, LCR =1.5±0.6, all P<0.0001). Conclusion: ⁶⁸Ga-pentixafor PET/CT imaging exhibits great potential for noninvasive functional lateralization and characterization of patients with adrenocortical masses.

Role of unilateral adrenalectomy in bilateral adrenal hyperplasias with Cushing's syndrome

Primary bilateral adrenocortical hyperplasias are rare forms of pituitary ACTH-independent Cushing's syndrome (CS). They are divided between primary bilateral macronodular adrenal hyperplasia (PBMAH) and micronodular adrenal hyperplasia (MiBAH), which is subdivided in primary pigmented nodular adrenocortical disease (PPNAD) and isolated micronodular adrenocortical disease (i-MAD). One of the most debated aspects surrounding these entities is their most appropriate therapy. Although bilateral adrenalectomy (BA) has previously been the most utilized therapy for patients with overt CS, recent studies have indicated that unilateral adrenalectomy (UA) can be effective in patients with PBMAH and some with MiBAH with fewer long-term side effects. Medical therapies can also be used for bridging to surgery or rarely in the long-term for these patients. We review the various degrees of CS resulting from PBMAH and MiBAH, with a special focus on their respective therapies including UA, taking into account the recent pathophysiological and genetics findings.

Adrenally Directed Medical Therapies for Cushing Syndrome

CONTEXT

Endogenous Cushing syndrome (CS) is characterized by excess cortisol secretion, which is driven by tumorous secretion of corticotropin in the majority of patients. Untreated, CS results in substantial morbidity and mortality. Tumor-directed surgery is generally the first-line therapy for CS. However, hypercortisolism may persist or recur postoperatively; in other cases, the underlying tumor may not be resectable or its location may not be known. Yet other patients may be acutely ill and require stabilization before definitive surgery. In all these cases, additional interventions are needed, including adrenally directed medical therapies.

EVIDENCE ACQUISITION

Electronic literature searches were performed to identify studies pertaining to adrenally acting agents used for CS. Data were abstracted and used to compile this review article.

EVIDENCE SYNTHESIS

Adrenally directed medical therapies inhibit one or several enzymes involved in adrenal steroidogenesis. Several adrenally acting medical therapies for CS are currently available, including ketoconazole, metyrapone, osilodrostat, mitotane, and etomidate. Additional agents are under investigation. Drugs differ with regards to details of their mechanism of action, time course of pharmacologic effect, safety and tolerability, potential for drug-drug interactions, and route of administration. All agents require careful dose titration and patient monitoring to ensure safety and effectiveness, while avoiding hypoadrenalism.

CONCLUSIONS

These medications have an important role in the management of CS, particularly among patients with persistent or recurrent hypercortisolism postoperatively or those who cannot undergo tumor-directed surgery. Use of these drugs mandates adequate patient instruction and close monitoring to ensure treatment goals are being met while untoward adverse effects are minimized.

[Immunohistochemical study on the expression/hyperexpression of aberrant/eutopic receptors in patients with bilateral macronodular adrenal hyperplasia]

Bilateral macronodular adrenal hyperplasia (BMAH) is a rare cause of Cushing's syndrome. In this case cortisol production can be regulated by both genetic factors and various molecular mechanisms. The presence of aberrant or overexpression of eutopic receptors on the membrane of adrenal cortex may lead to activation of cAMP/PKA signaling pathways and consequently, pathological stimulation of steroidogenesis. Since proving the effectiveness of unilateral adrenalectomy in BMAH by achievement of stable remission, preoperative clinical and laboratory tests (ligand-induced tests) are no longer of relevant. Nevertheless, in the absence of normalization of the level of cortisol in the postoperative period or its recurrence, subsequent specific targeted medical options can be offered only if expression/hyperexpression predominance of one or another receptor. Their detection becomes possible using more reliable diagnostic methods such as polymerase chain reaction (PCR) and immunohistochemical studies (IHC) than clinical laboratory tests. At the moment, PCR has gained a wider application. This article summarizes data on the use of immunohistochemical study in BMAH.

Adrenal Incidentaloma

An adrenal incidentaloma is now established as a common endocrine diagnosis that requires a multidisciplinary approach for effective management. The majority of patients can be reassured and discharged, but a personalized approach based upon image analysis, endocrine workup, and clinical symptoms and signs are required in every case. Adrenocortical carcinoma remains a real concern but is restricted to <2% of all cases. Functional adrenal incidentaloma lesions are commoner (but still probably <10% of total) and the greatest challenge remains the diagnosis and optimum management of autonomous cortisol secretion. Modern-day surgery has improved outcomes and novel radiological and urinary biomarkers will improve early detection and patient stratification in future years to come.

ARMC5 Primary Bilateral Macronodular Adrenal Hyperplasia Associated with a Meningioma: A Family Report

Primary bilateral adrenal macronodular hyperplasia is characterized by functioning adrenal macronodules and variable cortisol secretion. Familial clustering suggests a genetic cause that has been confirmed with the identification of some genetic mutations, including inactivating germline mutations, in armadillo repeat containing 5 (ARMC5) gene. The identification of the pathogenic variant enables the physician to identify and treat these patients earlier and more effectively. It has also been noticed that patients with germline causative variants show a different clinical spectrum, presenting specific clinical characteristics, as the association with the presence of meningiomas.

Update of Genetic and Molecular Causes of Adrenocortical Hyperplasias Causing Cushing Syndrome

Bilateral hyperplasias of the adrenal cortex are rare causes of chronic endogenous hypercortisolemia also called Cushing syndrome. These hyperplasias have been classified in two categories based on the adrenal nodule size: the micronodular types include Primary Pigmented Nodular Adrenocortical Disease (PPNAD) and isolated Micronodular Adrenal Disease (iMAD) and the macronodular also named Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH). This review discusses the genetic and molecular causes of these different forms of hyperplasia that involve mutations and dysregulation of various regulators of the cAMP/protein kinase A (PKA) pathway. PKA signaling is the main pathway controlling cortisol secretion in adrenocortical cells under ACTH stimulation. Although mutations of the regulatory subunit R1α of PKA (PRKAR1A) is the main cause of familial and sporadic PPNAD, inactivation of two cAMP-binding phosphodiesterases (PDE11A and PDE8B) are associated with iMAD even if they are also found in PPNAD and PBMAH cases. Interestingly, PBMAH that is observed in multiple familial syndrome such as APC, menin, fumarate hydratase genes, has initially been associated with the aberrant expression of G-protein coupled receptors (GPCR) leading to an activation of cAMP/PKA pathway. However, more recently, the discovery of germline mutations in Armadillo repeat containing protein 5 (ARMC5) gene in 25-50% of PBMAH patients highlights its importance in the development of PBMAH. The potential relationship between ARMC5 mutations and aberrant GPCR expression is discussed as well as the potential other causes of PBMAH.

Mass spectrometry-based steroid profiling in primary bilateral macronodular adrenocortical hyperplasia

Biochemical characterization of primary bilateral macronodular adrenocortical hyperplasia (PBMAH) by distinct plasma steroid profiles and its putative correlation to disease has not been previously studied. LC-MS/MS-based steroid profiling of 16 plasma steroids was applied to 36 subjects (22 females, 14 males) with PBMAH, 19 subjects (16 females, 3 males) with other forms of adrenal Cushing's syndrome (ACS), and an age and sex-matched control group. Germline ARMC5 sequencing was performed in all PBMAH cases. Compared to controls, PBMAH showed increased plasma 11-deoxycortisol, corticosterone, 11-deoxycorticosterone, 18-hydroxycortisol, and aldosterone, but lower progesterone, DHEA, and DHEA-S with distinct differences in subjects with and without pathogenic variants in ARMC5. Steroids that showed isolated differences included cortisol and 18-oxocortisol with higher (P < 0.05) concentrations in ACS than in controls and aldosterone with higher concentrations in PBMAH when compared to controls. Larger differences in PBMAH than with ACS were most clear for corticosterone, but there were also trends in this direction for 18-hydroxycortisol and aldosterone. Logistic regression analysis indicated four steroids - DHEA, 11-deoxycortisol, 18-oxocortisol, and corticosterone - with the most power for distinguishing the groups. Discriminant analyses with step-wise variable selection indicated correct classification of 95.2% of all subjects of the four groups using a panel of nine steroids; correct classification of subjects with and without germline variants in ARMC5 was achieved in 91.7% of subjects with PBMAH. Subjects with PBMAH show distinctive plasma steroid profiles that may offer a supplementary single-test alternative for screening purposes.

Adrenocortical hyperplasia: A multifaceted disease

Adrenocortical hyperplasia may develop in different contexts. Primary adrenal hyperplasia may be secondary to primary bilateral macronodular adrenocortical hyperplasia (PBMAH) or micronodular bilateral adrenal hyperplasia (MiBAH) which may be divided in primary pigmented nodular adrenocortical disease (PPNAD) and isolated micronodular adrenocortical disease (i-MAD). Both lead to oversecretion of cortisol and potentially to Cushing's syndrome. Moreover, adrenocortical hyperplasia may be secondary to longstanding ACTH stimulation in ACTH oversecretion as in Cushing's disease, ectopic ACTH secretion or glucocorticoid resistance syndrome and congenital adrenal hyperplasia secondary to various enzymatic defects within the cortex. Finally, idiopathic bilateral adrenal hyperplasia is the most common cause of primary aldosteronism. We will discuss recent findings on the multifaceted forms of adrenocortical hyperplasia.

Cushing's syndrome: Treatment and new therapeutic approaches

Overt Cushing's syndrome is a severe condition responsible for multiple comorbidities and increased mortality. Effective treatment is essential to reduce mortality, improve comorbidities and long-term quality of life. Surgical resection of the causal lesion(s) is generally the first-line and most effective treatment to normalize cortisol secretion. Adjunctive symptomatic treatments of co-morbidities are often necessary both during the active phase of the disease and for persisting co-morbidities after cessation of hypercortisolism. Second-line treatments include various pharmacological treatments, bilateral adrenalectomy, and radiotherapy of corticotroph tumors. The choice of these treatments is complex, must be performed in a multidisciplinary expert team to be individualized for each patient, and use a shared decision-making approach.

The pathogenic role of the GIP/GIPR axis in human endocrine tumors: emerging clinical mechanisms beyond diabetes

The glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone produced in the gastrointestinal tract in response to nutrients. GIP has a variety of effects on different systems, including the potentiation of insulin secretion from pancreatic β-cells after food intake (i.e. incretin effect), which is probably the most important. GIP effects are mediated by the GIP receptor (GIPR), a G protein-coupled receptor expressed in several tissues, including islet β-cells, adipocytes, bone cells, and brain. As well as its involvement in metabolic disorders (e.g. it contributes to the impaired postprandial insulin secretion in type 2 diabetes (T2DM), and to the pathogenesis of obesity and associated insulin resistance), an inappropriate GIP/GIPR axis activation of potential diagnostic and prognostic value has been reported in several endocrine tumors in recent years. The ectopic GIPR expression seen in patients with overt Cushing syndrome and primary bilateral macronodular adrenal hyperplasia or unilateral cortisol-producing adenoma has been associated with an inverse rhythm of cortisol secretion, with low fasting morning plasma levels that increase after eating. On the other hand, most acromegalic patients with an unusual GH response to oral glucose suppression have GIPR-positive somatotropinomas, and a milder phenotype, and are more responsive to medical treatment. Neuroendocrine tumors are characterized by a strong GIPR expression that may correlate positively or inversely with the proliferative index MIB-1, and that seems an attractive target for developing novel radioligands. The main purpose of this review is to summarize the role of the GIP/GIPR axis in endocrine neoplasia, in the experimental and the clinical settings.

Advances in the medical treatment of Cushing's syndrome

Cushing's syndrome is associated with multisystem morbidity and, when suboptimally treated, increased mortality. Medical therapy is an option for patients if surgery is not successful and can be classified into pituitary-directed drugs, steroid synthesis inhibitors, and glucocorticoid receptor antagonists. In the last decade there have been new developments in each drug category. Targeting dopamine and somatostatin receptors on corticotroph adenomas with cabergoline or pasireotide, or both, controls cortisol production in up to 40% of patients. Potential new targets in corticotroph adenomas include the epidermal growth factor receptor, cyclin-dependent kinases, and heat shock protein 90. Osilodrostat and levoketoconazole are new inhibitors of steroidogenesis and are currently being evaluated in multicentre trials. CORT125134 is a new selective glucocorticoid receptor antagonist under investigation. We summarise the drug therapies for various forms of Cushing's syndrome and focus on emerging drugs and drug targets that have the potential for new and effective tailor-made pharmacotherapy for patients with Cushing's syndrome.

Autonomous cortisol secretion in adrenal incidentalomas

Adrenal incidentalomas (AI) are one of the most frequent reasons for consultation in Endocrinology, as they are present in 3-10% of the general population. Up to 20% of them may have autonomous cortisol secretion (ACS), a term that refers to AI carriers with biochemical evidence of excess cortisol, but without the "specific" clinical signs of Cushing's syndrome. As ACS is associated with an increased risk of diabetes, obesity, high blood pressure (HBP), osteoporosis, cardiovascular events, and global mortality; its correct identification is of great importance. There are different laboratory assays to detect ACS, but all of them have some limitations. The dexamethasone suppression test is the most accepted for screening. However, there is no consensus on the cutoff point that should be used. Low levels of ACTH and DHEA-S and high urinary free cortisol are also associated with ACS, but in isolation they are of little value to establish the diagnosis. Considering its clinical implications and the lack of consensus in the diagnosis and in which is the most appropriate management of these patients, this review offers a quick reference guide of ACS, presenting an exhaustive review of the topic: its definition, epidemiology, diagnosis, clinical implications, treatment, and follow-up.

Retention of aberrant cortisol secretion in a patient with bilateral macronodular adrenal hyperplasia after unilateral adrenalectomy

Aberrant cortisol secretion responses after exogenous stimuli such as upright posture, eating a mixed meal or receiving agents influencing aberrant G-protein-coupled receptors in adrenal glands, are often observed in patients with bilateral macronodular adrenal hyperplasia (BMAH). However, little is known about whether this aberrant response is retained after unilateral adrenalectomy. Here, we describe a 61-year-old postmenopausal Japanese woman with unsatisfactorily controlled hypertension who was referred to us for further investigation due to her pre-obesity characteristics (body mass index 28.4 kg/m²). Cushing’s signs and serum cortisol at 16.2 µg/dL with undetectable adrenocorticotropic hormone indicated adrenal Cushing’s syndrome. Adrenal imaging revealed bilaterally enlarged adrenal glands with 131-I adosterol uptake; hence, BMAH was diagnosed. Preoperatively, in vivo screening for aberrant adrenal receptors revealed an aberrant response of cortisol secretion on metoclopramide challenge. The patient underwent unilateral adrenalectomy; thereafter, glucocorticoid replacement therapy was reduced to hydrocortisone 15 mg/day at postoperative day 6. Fasting morning serum cortisol level measured at postoperative day 8 was 2.96 µg/dL, suggesting adrenal insufficiency. However, following metoclopramide administration serum cortisol level rose to 19.7 µg/dL, indicating potential efficient adrenal function. Aberrant cortisol secretory capacity was thus preserved in BMAH, even in a state of adrenal insufficiency after unilateral adrenalectomy. Caution should be exercised when assessing the hypothalamus-pituitary-adrenal axis, because in this patient, a high cortisol level did not guarantee appropriate adrenal function when the patient was challenged by exogenous stimuli.

TRH-induced secretion of adrenocorticotropin and cortisol in dogs with pituitary-dependent hypercortisolism

Background: In dogs, spontaneous Cushing’s syndrome is most often pituitary-dependent and caused by hypersecretion of adrenocorticotropic hormone (ACTH), resulting in increased adrenocortical glucocorticoid secretion similar to horses. In horses with Cushing’s syndrome (or pituitary pars intermedia dysfunction [PPID]) a thyrotropin-releasing hormone (TRH) stimulation test can be used for diagnosis, as TRH administration results in increased circulating ACTH and cortisol concentrations in affected horses.

Objective: The aim of this study was to investigate the effect of TRH administration on the circulating ACTH and cortisol concentrations in dogs with pituitary-dependent hypercortisolism (PDH).

Methods: Ten clinically normal control dogs and 10 dogs with PDH, all client owned, underwent a TRH stimulation test with measurement of plasma concentrations of ACTH and cortisol, before and after intravenous administration of 10 μg TRH/kg bodyweight.

Results: Plasma ACTH concentration did not rise significantly after TRH stimulation, neither in PDH dogs nor in clinically normal dogs. In contrast, the plasma cortisol concentration did increase significantly after TRH stimulation in both groups (p = .003 in PDH and p < .001 in control). Immunohistochemistry of normal adrenal glands demonstrated the presence of TRH receptors in the whole adrenal cortex.

Conclusions: The results of this study demonstrate that the TRH stimulation test should be rejected as a tool to diagnose PDH in dogs. The observed TRH-induced increase in plasma cortisol concentration without a significant rise in plasma ACTH concentration may be explained by a direct effect of TRH on adrenocortical cells mediated by adrenocortical TRH receptors.

Two cases of Cushing's syndrome due to primary bilateral macronodular adrenal hyperplasia secondary to aberrant adrenal expression of hormone receptors

OBJECTIVES

Primary bilateral macronodular adrenal hyperplasia is an uncommon cause of endogenous Cushing's syndrome characterized by the presence of aberrant adrenal expression of ectopic receptors that regulate steroidogenesis by mimicking the events triggered by ACTH receptor activation. Receptors of this type have been described for several hormones. The aim of the study is to detect these receptors in two patients with ACTH-independent hypercortisolism by means of the application of a screening protocol.

DESIGN AND METHODS

A protocolized study of aberrant receptors was performed including measurements of ACTH, cortisol and other steroids and hormones. Upright posture test, mixed food and administration of Gonadotropin-Releasing Hormone (GnRH) were used as stimuli. In both patients, a stimulation test with intravenous ACTH was conducted to determinate the cortical response capacity. The study was carried out in three separate days.

RESULTS

The first patient, who had a hypergonadotropic hypogonadism, presented anomalous cortisol response to the GnRH stimulation, with potential medical treatment by the use of exogenous testosterone. In the second case, the patient with clinical Cushing's syndrome presented anomalous cortisol response to standing, whose potential medical treatment would be the use of beta-blockers.

CONCLUSIONS

This etiological variant of ACTH-independent Cushing's syndrome leads to the use of specific pharmacologic therapies in some cases as alternatives to adrenalectomy. The studied cases show the importance of having a high degree of suspicion when diagnosing less frequent types of Cushing's syndrome.

Recent Advances on Subclinical Hypercortisolism

During the last 20 years, a significant body of literature has accumulated regarding subclinical hypercortisolism in patients with adrenal incidentalomas. Retrospective studies have indicated these patients have an increase in cardiovascular events and mortality. Current recommendations for patients with adrenal incidentalomas include an overnight low-dose dexamethasone suppression test and a thorough evaluation of cardiovascular and metabolic risk factors. Further hormonal testing and close monitoring are necessary in patients with incomplete suppression. Unilateral adrenalectomy may be beneficial in cases with abnormal suppression and comorbidities related to hypercortisolemia. Prospective studies are need for a better risk stratification and tailored therapy.

Aberrant G-protein coupled hormone receptor in adrenal diseases

The regulation of cortisol or aldosterone production when ACTH of pituitary origin or the renin-angiotensin systems are suppressed in primary adrenal Cushing's syndrome or in primary aldosteronism is exerted by diverse genetic and molecular mechanisms. In addition to recently identified mutations in various genes implicated in the cyclic AMP or ion channel pathways, steroidogenesis is not really autonomous as it is frequently regulated by the aberrant adrenocortical expression of diverse hormone receptors, particularly G-protein coupled hormone receptors (GPCR) which can substitute for the normal function of ACTH or angiotensin-II. In addition, paracrine or autocrine production of ligands for the aberrant GPCR such as ACTH or serotonin is found in some adrenal tumors or hyperplasias and participates in a complex regulatory loop causing steroid excess. Targeted therapies to block the aberrant ligands or their receptors could become useful in the future, particularly for patients with bilateral source of steroid excess.

Vasopressin and metabolic disorders: translation from experimental models to clinical use

Vasopressin has many physiological actions in addition to its well-defined role in the control of fluid homeostasis and urine concentration. An increasing body of evidence suggests that the vasopressin-hydration axis plays a role in glucose homeostasis. This review summarizes the knowledge accumulated over the last decades about the influence of vasopressin in the short-term regulation of glycaemia. It describes the possible role of this hormone through activation of V1a and V1b receptors on liver and pancreas functions and on the hypothalamic-pituitary-adrenal axis. Moreover, we report recent in vivo studies demonstrating the role of vasopressin in the long-term regulation of glycaemia. Indeed, V1a- or double-V1aV1b-receptor knockout mice display significant changes in the glucose and lipid metabolism. In rats, sustained high V1aR activation increases basal glycaemia and aggravates glucose intolerance in obese rats. Finally, the translation from animal findings to human was evidenced by epidemiological and genetic studies that showed that high vasopressin level is a risk factor for hyperglycaemia, metabolic disorders and diabetes.

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

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.

Prevalence of primary aldosteronism without hypertension in the general population: Results in Shika study

OBJECTIVE

Recent studies have reported a high prevalence of primary aldosteronism (PA) among hypertensive patients. However, few data exist regarding the prevalence of PA in the general population. Therefore, we examined the prevalence of PA in the general population including normotensive subjects.

METHODS

Plasma renin activity (ng/mL/hr), plasma aldosterone concentration (pg/mL) and aldosterone renin ratio (ARR) were determined in 309 subjects aged >40 years in Horimatsu and Higashi-Matsuho district, Shika-machi, Ishikawa, Japan.

RESULTS

Among them, 195 subjects (78 males, mean age: 62 ± 11 years) did not take antihypertensive agents: 113 normotensive subjects and 82 hypertensive subjects. Under these conditions, 68 subjects (13 males, age 62 ± 10 years) had an ARR >200. In 14 subjects who underwent captopril suppression test, PA was documented in 5 subjects, yielding a minimum prevalence of 2.6% in total subjects (1.8% in normotensive subjects and 3.7% in hypertensive subjects). Interestingly, females subjects demonstrated significant differences in ARR between subjects with age <50 (172 ± 105) and those with age 51-60 (388 ± 531), although there were no differences in male subjects.

CONCLUSIONS

These results demonstrate that PA including normotensive subjects exists more commonly than that expected in the general population. We suggest further investigation about the cause and progression of PA associated with sex and aging.

The GIP/GIPR axis is functionally linked to GH-secretion increase in a significant proportion of gsp- somatotropinomas

OBJECTIVE

Glucose-dependent insulinotropic polypeptide receptor (GIPR) overexpression has been recently described in a proportion of gsp^- somatotropinomas and suggested to be associated with the paradoxical increase of GH (GH-PI) during an oral glucose load.

DESIGN AND METHODS

This study was aimed at linking the GIP/GIPR pathway to GH secretion in 25 somatotropinomas-derived primary cultures and correlating molecular with clinical features in acromegalic patients. Given the impairment of the GIP/GIPR axis in acromegaly, an additional aim was to assess the effect of GH/IGF-1 stimulation on GIP expression in the enteroendocrine cell line STC-1.

RESULTS

Nearly 80% of GIPR-expressing somatotropinomas, all of them negative for gsp mutations, show increased GH secretion upon GIP stimulation, higher sensitivity to Forskolin but not to somatostatin analogs. Besides increased frequency of GH-PI, GIPR overexpression does not appear to affect acromegalic patients' clinical features. In STC-1 cells transfected with GIP promoter-driven luciferase vector, IGF-1 but not GH induced dose-dependent increase in luciferase activity.

CONCLUSIONS

We demonstrate that GIPR mediates the GH-PI in a significant proportion of gsp^- acromegalic patients. In these cases, the stimulatory effect of IGF-1 on GIP promoter support the hypothesis of a functional GH/IGF-1/GIP axis. Further studies based on larger cohorts and the development of a stable transgenic model with inducible GIPR overexpression targeted to pituitary somatotroph lineage will be mandatory to establish the real role of GIPR in the pathogenesis of somatotropinomas.

A multicenter experience on the prevalence of ARMC5 mutations in patients with primary bilateral macronodular adrenal hyperplasia: from genetic characterization to clinical phenotype

ARMC5 mutations have recently been identified as a common genetic cause of primary bilateral macronodular adrenal hyperplasia (PBMAH). We aimed to assess the prevalence of ARMC5 germline mutations and correlate genotype with phenotype in a large cohort of PBMAH patients. A multicenter study was performed, collecting patients from different endocrinology units in Italy. Seventy-one PBMAH patients were screened for small mutations and large rearrangements in the ARMC5 gene: 53 were cortisol-secreting (two with a family history of adrenal hyperplasia) and 18 were non-secreting cases of PBMAH. Non-mutated and mutated patients' clinical phenotypes were compared and related to the type of mutation. A likely causative germline ARMC5 mutation was only identified in cortisol-secreting PBMAH patients (one with a family history of adrenal hyperplasia and ten apparently sporadic cases). Screening in eight first-degree relatives of three index cases revealed four carriers of an ARMC5 mutation. Evidence of a second hit at somatic level was identified in five nodules. Mutated patients had higher cortisol levels (p = 0.062), and more severe hypertension and diabetes (p < 0.05). Adrenal glands were significantly larger, with a multinodular phenotype, in the mutant group (p < 0.01). No correlation emerged between type of mutation and clinical parameters. ARMC5 mutations are frequent in cortisol-secreting PBMAH and seem to be associated with a particular pattern of the adrenal masses. Their identification may have implications for the clinical care of PBMAH cases and their relatives.

Role of cAMP/PKA pathway and T-type calcium channels in the mechanism of action of serotonin in human adrenocortical cells

In human adrenal, serotonin (5-HT), produced by mast cells located in zona glomerulosa, stimulates production of corticosteroids through a paracrine mechanism involving the 5-HT receptor type 4 (5-HT₄). The aim of the present study was to investigate the transduction mechanisms associated with activation of 5-HT₄ receptors in human adrenocortical cells. Our results show that 5-HT₄ receptors are present in the outer adrenal cortex, both in glomerulosa and fasciculata zonae. In the zona glomerulosa. 5-HT₄ receptor was detected both in immunopositive and immunonegative cells for 11β-hydroxylase, an enzyme involved in cortisol synthesis. The data demonstrate that 5-HT₄ receptors are positively coupled to adenylyl cyclases and cAMP-dependent protein kinases (PKA). The activation of the cAMP-PKA pathway is associated with calcium influx through T-type calcium channels. Both the adenylyl cyclase/PKA pathway and the calcium influx are involved in 5-HT-induced cortisol secretion.

ENDOCRINE TUMOURS: The genomics of adrenocortical tumors

The last decade witnessed the emergence of genomics, a set of high-throughput molecular measurements in biological samples. These pan-genomic and agnostic approaches have revolutionized the molecular biology and genetics of malignant and benign tumors. These techniques have been applied successfully to adrenocortical tumors. Exome sequencing identified new major drivers in all tumor types, including KCNJ5, ATP1A1, ATP2B3 and CACNA1D mutations in aldosterone-producing adenomas (APA), PRKACA mutations in cortisol-producing adenomas (CPA), ARMC5 mutations in primary bilateral macronodular adrenocortical hyperplasia (PBMAH) and ZNRF3 mutations in adrenocortical carcinomas (ACC). Moreover, the various genomic approaches - including exome sequencing, transcriptome, miRNome, genome and methylome - converge into a single molecular classification of adrenocortical tumors. Especially for ACC, two main molecular groups have emerged, showing major differences in outcomes. These ACC groups differ by their gene expression profiles, but also by recurrent mutations and specific DNA hypermethylation patterns in the subgroup of poor outcome. The clinical impact of these findings is just starting. The main altered signaling pathways now become therapeutic targets. The molecular groups of diseases individualize robust subtypes within diseases such as APA, CPA, PBMAH and ACC. A revised nosology of adrenocortical tumors should impact the clinical research. Obvious consequences also include genetic counseling for the new genetic diseases such as ARMC5 mutations in PBMAH, and a better prognostication of ACC based on targeted measurements of a few discriminant molecular alterations. Identifying the main molecular groups of adrenocortical tumors by extensively gathering the molecular variations is a significant step forward towards precision medicine.

Role of ACTH and Other Hormones in the Regulation of Aldosterone Production in Primary Aldosteronism

The major physiological regulators of aldosterone production from the adrenal zona glomerulosa are potassium and angiotensin II; other acute regulators include adrenocorticotropic hormone (ACTH) and serotonin. Their interactions with G-protein coupled hormone receptors activate cAMP/PKA pathway thereby regulating intracellular calcium flux and CYP11B2 transcription, which is the specific steroidogenic enzyme of aldosterone synthesis. In primary aldosteronism (PA), the increased production of aldosterone and resultant relative hypervolemia inhibits the renin and angiotensin system; aldosterone secretion is mostly independent from the suppressed renin-angiotensin system, but is not autonomous, as it is regulated by a diversity of other ligands of various eutopic or ectopic receptors, in addition to activation of calcium flux resulting from mutations of various ion channels. Among the abnormalities in various hormone receptors, an overexpression of the melanocortin type 2 receptor (MC2R) could be responsible for aldosterone hypersecretion in aldosteronomas. An exaggerated increase in plasma aldosterone concentration (PAC) is found in patients with PA secondary either to unilateral aldosteronomas or bilateral adrenal hyperplasia (BAH) following acute ACTH administration compared to normal individuals. A diurnal increase in PAC in early morning and its suppression by dexamethasone confirms the increased role of endogenous ACTH as an important aldosterone secretagogue in PA. Screening using a combination of dexamethasone and fludrocortisone test reveals a higher prevalence of PA in hypertensive populations compared to the aldosterone to renin ratio. The variable level of MC2R overexpression in each aldosteronomas or in the adjacent zona glomerulosa hyperplasia may explain the inconsistent results of adrenal vein sampling between basal levels and post ACTH administration in the determination of source of aldosterone excess. In the rare cases of glucocorticoid remediable aldosteronism, a chimeric CYP11B2 becomes regulated by ACTH activating its chimeric CYP11B1 promoter of aldosterone synthase in bilateral adrenal fasciculate-like hyperplasia. This review will focus on the role of ACTH on excess aldosterone secretion in PA with particular focus on the aberrant expression of MC2R in comparison with other aberrant ligands and their GPCRs in this frequent pathology.

Pregnancy, Primary Aldosteronism, and Adrenal CTNNB1 Mutations

Recent discoveries of somatic mutations permit the recognition of subtypes of aldosterone-producing adenomas with distinct clinical presentations and pathological features. Here we describe three women with hyperaldosteronism, two who presented in pregnancy and one who presented after menopause. Their aldosterone-producing adenomas harbored activating mutations of CTNNB1, encoding β-catenin in the Wnt cell-differentiation pathway, and expressed LHCGR and GNRHR, encoding gonadal receptors, at levels that were more than 100 times as high as the levels in other aldosterone-producing adenomas. The mutations stimulate Wnt activation and cause adrenocortical cells to de-differentiate toward their common adrenal-gonadal precursor cell type. (Funded by grants from the National Institute for Health Research Cambridge Biomedical Research Centre and others.).