Aldosterone-producing Adrenocortical Adenoma Research Articles

The results of immunohistochemical study of antibodies to CYP11B2 in primary hyperaldosteronism

Background: Aldosterone-producing adrenocortical adenoma (APA) is responsible for the majority of cases clinically diagnosed as primary aldosteronism. Aldosterone synthase (CYP11B2) is one of the enzymes that play essential roles in aldosterone synthesis and is involved in the pathogenesis of primary aldosteronism. Recent studies have demonstrated that various factors influence the expression and function of CYP11B2 in APA. In particular, somatic mutations, such as gain-of-function and loss-of-function mutations have been identified in several genes, each of which encodes a pivotal protein that affects the calcium signaling pathway, the expression of CYP11B2, and aldosterone production. On the other hand, CYP11B2 also catalyzes the conversion of cortisol to 18-hydroxycortisol and subsequently converts 18-hydroxycortisol to 18-oxocortisol. The article also discusses the clinical significance of 18-oxocortisol, an important biomarker for the diagnosis of primary aldosteronism. Somatic mutations in aldosterone-driver genes are strongly associated with CYP11B2 expression and have been only detected in the CYP11B2-positive tumor area, that indicating heterogeneous expression of CYP11B2 in tumor.Aim: to assess the functional heterogeneity of adrenal tumors in primary aldosteronismMaterials and methods: Retrospective evaluation adrenal tumors from patients with primary aldosteronism (n=20). According to CT unilateral macrohyperplasia was detected in 19 patients (95% of total), all of them were confirmed to have unilateral hyperproduction of aldosterone according to AVS. Selected tumors werestained with anty-CYP11B2 antibody. We evaluated the CYP11B2 expression in the adenoma and in the adjacent adrenal cortex.Results: Immunohistochemistry studies of the resected adrenals from 20 patients with PA operated due to unilateral production of aldosterone using CYP11B2 staining showed that 10 of those with an adenoma on CT scanning showed CYP11B2 staining in the adenoma. Furthermore, 5 cases of an unilateral adenoma, showed CYP11B2 staining in the adjacent adrenal cortex and an absence of staining for CYP11B2 in the adenoma. 5 cases showed CYP11B2 expression is heterogeneously immunolocalized throughout the tumor area.Conclusion: Thus, the functional heterogeneity of adrenal tumors in primary aldosteronism has been proven. It is necessary to compare the data of immunohistochemical studies on the expression of CYP11B2 with the indicators of the level of 18-hydroxycortisol, 18-oxocortisol.

In Silico Analysis of the Gene Expression Patterns between Aldosterone-Producing Adenoma and Nonfunctional Adrenocortical Adenoma.

Primary aldosteronism is the most common form of secondary hypertension, and aldosteronoma makes up a significant proportion of primary aldosteronism cases. Aldosteronoma is also called aldosterone-producing adenoma (APA). Although there have been many studies about APA, the pathogenesis of this disease is not yet fully understood. In this study, we aimed to find out the difference of gene expression patterns between APA and nonfunctional adrenocortical adenoma (NFAA) using a weighted gene coexpression network (WGCNA) and differentially expressed gene (DEG) analysis; only the genes that meet the corresponding standards of both methods were defined as real hub genes and then used for further analysis. Twenty-nine real hub genes were found out, most of which were enriched in the phospholipid metabolic process. WISP2, S100A10, SSTR5-AS1, SLC29A1, APOC1, and SLITRK4 are six real hub genes with the same gene expression pattern between the combined and validation datasets, three of which indirectly or directly participate in lipid metabolism including WISP2, S100A10, and APOC1. According to the gene expression pattern of DEGs, we speculated five candidate drugs with potential therapeutic value for APA, one of which is cycloheximide, an inhibitor for phospholipid biosynthesis. All the evidence suggests that phospholipid metabolism may be an important pathophysiological mechanism for APA. Our study provides a new perspective regarding the pathophysiological mechanism of APA and offers some small molecules that may possibly be effective drugs against APA.

MiR-193a-3p functions as a tumour suppressor in human aldosterone-producing adrenocortical adenoma by down-regulating CYP11B2.

The mechanism of aldosterone-producing adrenocortical adenoma (APA) pathogenesis and the role of microRNAs (miRNAs) in APA pathogenesis have not been completely clarified. We examined the expression and function of miR-140-3p, miR-193a-3p and miR-22-3p, which have binding sites in CYP11B2. Expression of miRNAs and CYP11B2 mRNA was measured by quantitative reverse transcription PCR (qRT-PCR). Cell proliferation was monitored by colorimetric analysis, and cell apoptosis and cell cycle progression were analysed by flow cytometry. ELISA was carried out to detect aldosterone levels in cell culture supernatants. Luciferase reporter assays, qRT-PCR and Western blotting were performed to identify CYP11B2 as a target of miR-193a-3p. Of the three miRNAs examined, miR-193a-3p exhibited a significant decrease and CYP11B2 mRNA exhibited a significant increase in expression in APA compared with adjacent normal adrenal gland tissue. Transfection of miR-193a-3p mimic into the human adrenocortical cell line H295R showed that elevated miR-193a-3p expression inhibits proliferation and aldosterone secretion, induces G1-phase arrest and promotes apoptosis in H295R cells. Furthermore, in luciferase reporter assays, overexpression of miR-193a-3p in H295R cells significantly reduced the luciferase activity of the wild-type CYP11B2 3'-UTR construct, which could be reversed by mutation of the miR-193a-3p-binding site. Moreover, miR-193a-3p overexpression downregulated CYP11B2 mRNA and protein expression. Finally, overexpression of CYP11B2 diminished the effects of miR-193a-3p on H295R cells. Taken together, our results suggest that CYP11B2 levels may be modulated by miR-193a-3p in APA, which could explain, at least partially, why downregulation of miR-193a-3p during APA formation may promote cell growth and suppress apoptosis.

Tumor microenvironment in functional adrenocortical adenomas: immune cell infiltration in cortisol-producing adrenocortical adenoma

The tumor microenvironment plays pivotal roles in various human neoplasms. However, that of benign tumor, particularly hormone-secreting endocrine tumors, has remained virtually unknown. Therefore, we firstly attempted to analyze the tumor microenvironment of autonomous hormone-secreting adrenocortical adenomas. We first histologically evaluated 21 cortisol-producing adrenocortical adenoma (CPA) and 13 aldosterone-producing adrenocortical adenoma (APA) cases. Quantitative histologic analysis revealed that intratumoral immune cell infiltration (ICI) was more pronounced in CPAs than in APAs. We then evaluated the cytokine and chemokine profiles using polymerase chain reaction arrays in APAs and CPAs. Angiogenic chemokines, C-X-C motif chemokine ligand (CXCL) 1 and CXCL2, were significantly more abundant in CPAs than in APAs using subsequent quantitative polymerase chain reaction and immunohistochemical analyses. We then examined the vascular density between these 2 adenomas, and the density was significantly higher in overt CPAs than in APAs. Of particular interest, CXCL12-positive vessels were detected predominantly in CPAs, and their infiltrating immune cells were C-X-C motif chemokine receptor 4 (CXCR4) positive. These results above indicated that CXCL12-CXCR4 signaling could partly account for ICI detected predominantly in CPAs. We then further explored the etiology of ICI in CPAs by evaluating the senescence of tumor cells possibly caused by excessive cortisol in CPAs. The status of senescence markers, p16 and p21, was significantly more abundant in CPAs than in APAs. In addition, all CPA cases examined were positive for senescence-associated β-galactosidase. These results all indicated that exposure to local excessive cortisol could result in senescence of tumors cells and play essential roles in constituting the characteristic tissue microenvironment of CPAs.

Adrenal Vein Sampling Is the Preferred Method to Select Patients With Primary Aldosteronism for Adrenalectomy: Con Side of the Argument.

Primary aldosteronism (PA) is a secondary form of hypertension caused by autonomous secretion of the sodium-retaining hormone aldosterone by one or both adrenal glands, leading to hypertension and in a subset of patients to hypokalemia.1 PA can be cured by adrenalectomy in patients who have a unilateral aldosterone-producing adrenocortical adenoma (APA), present in about half of patients. Cure has 2 aspects in this disease: most, but not all, patients are cured biochemically, that is, have normalization of aldosterone secretion, whereas only a minority will be cured from hypertension.2 The majority of patients who remain hypertensive after adrenalectomy will reach lower blood pressure levels with less medication. They will rarely need mineralocorticoid receptor antagonists like spironolactone. These mineralocorticoid receptor antagonists are indicated for the other half of patients with PA, who are thought to have bilateral adrenocortical hyperplasia. Although blood pressure and hypokalemia can be controlled in almost all patients by adrenalectomy or mineralocorticoid receptor antagonists, quality of life improves most after adrenalectomy.3 Hence, proper selection of patients for adrenalectomy is of critical importance to achieve an optimal outcome for patients. The Endocrine Society Clinical Practice guideline (guideline)1 recommends adrenal vein sampling (AVS) as the preferred method to select patients with PA for adrenalectomy. In AVS, adrenal veins are cannulated and from each a blood sample is drawn that is used to determine cortisol and aldosterone. Measurement of cortisol is critical to assess selectivity of cannulation of an adrenal vein and to correct for admixture of nonadrenal blood. The widely available and most frequently used alternative to AVS, the adrenal computed tomographic (CT) scan, is considered by the guideline to be inferior to identify APA. Indeed, the results of CT scanning and AVS differ in their conclusion on the presence of APA in almost 40% of cases …

Dysregulation of Aldosterone Secretion in Mast Cell-Deficient Mice.

Resident adrenal mast cells have been shown to activate aldosterone secretion in rat and man. Especially, mast cell proliferation has been observed in adrenal tissues from patients with aldosterone-producing adrenocortical adenoma. In the present study, we show that the activity of adrenal mast cells is stimulated by low-sodium diet and correlates with aldosterone synthesis in C57BL/6 and BALB/c mice. We have also investigated the regulation of aldosterone secretion in mast cell-deficient C57BL/6 KitW-sh/W-sh mice in comparison with wild-type C57BL/6 mice. KitW-sh/W-sh mice submitted to normal sodium diet had basal plasma aldosterone levels similar to those observed in wild-type animals. Conversely, low-sodium diet unexpectedly induced an exaggerated aldosterone response, which seemed to result from an increase in adrenal renin and angiotensin type 1 receptor expression. Severe hyperaldosteronism was associated with an increase in systolic blood pressure and marked hypokalemia, which favored polyuria. Adrenal renin and angiotensin type 1 receptor overexpression may represent a compensatory mechanism aimed at activating aldosterone production in the absence of mast cells. Finally, C57BL/6 KitW-sh/W-sh mice represent an unexpected animal model of primary aldosteronism, which has the particularity to be triggered by sodium restriction.

Expression of CYP11B2 in Aldosterone-Producing Adrenocortical Adenoma: Regulatory Mechanisms and Clinical Significance.

Aldosterone-producing adrenocortical adenoma (APA) is responsible for the majority of cases clinically diagnosed as primary aldosteronism. Aldosterone synthase (CYP11B2) is one of the enzymes that play essential roles in aldosterone synthesis and is involved in the pathogenesis of APA. Recent studies have demonstrated that various factors and regulators influence the expression and function of CYP11B2 in APA. In particular, somatic mutations, such as gain-of-function and loss-of-function mutations, have been identified in several genes, each of which encodes a pivotal protein that affects the calcium signaling pathway, the expression of CYP11B2, and aldosterone production. The gain-of-function mutations were reported in KCNJ5 that encodes G-protein activated inward rectifier K+ channel 4 (Kir3.4) and in CACNA1D, encoding calcium channel, voltage-dependent, L type, alpha subunit Cav1.3. The loss-of-function mutations were found in ATP1A1 that encodes Na+/K+ ATPase α subunit and in ATP2B3, encoding Ca2+ ATPase. Furthermore, the aberrant expression of gonadotropin-releasing hormone receptor is associated with the overexpression of CYP11B2 and overproduction of aldosterone in APA with activating mutations in CTNNB1 encoding β-catenin. On the other hand, CYP11B2 also catalyzes the conversion of cortisol to 18-hydroxycortisol and subsequently converts 18-hydroxycortisol to 18-oxocortisol. The recent studies have identified 18-oxocortisol as an important and distinct biomarker to diagnose primary aldosteronism. In this review, we summarize the recent findings on CYP11B2 and discuss the molecular pathogenesis of APA and the clinical significance of CYP11B2.

Laparoscopic Adrenalectomy in a Patient with Situs Inversus

Situs inversus is a relatively rare congenital disease. A patient with a right adrenal tumor complicated by total situs inversus was treated by laparoscopy. The patient was a 45-y-old male with lower limb weakness. He had been diagnosed with situs inversus during a general health check-up as an infant. His blood pressure was 230/160 mm Hg, and the serum potassium level was 2.0 mEq/L. Abdominal ultrasonography and magnetic resonance imaging showed a mass of about 2cm in diameter in contact with the right adrenal gland. Total situs inversus was simultaneously confirmed. The plasma aldosterone concentration was elevated to 442pg/mL, and renin activity was suppressed, at 0.3ng/mL/hr. These findings indicated a diagnosis of primary aldosteronism due to an adrenal tumor, and the right adrenal tumor was resected laparoscopically. The right adrenal gland was approached and resected from the lateral side of the spleen, which was located on the right side because of situs inversus. The resected specimen was 4.5cm x 1.6cm, and no intraoperative complications occurred. The histopathological examination showed the tumor to be an aldosterone-producing adrenocortical adenoma.

An Unusual Case of an Aldosterone-Producing Adrenocortical Adenoma Presenting with Rhabdomyolysis

Rhabdomyolysis is a rare presentation of hypokalemia, although muscle weakness is a well known manifestation of marked hypokalemia. Here, we report a case of primary hyperaldosteronism due to unilateral aldosterone-producing adenoma in a 14 year-old girl who developed rhabdomyolysis following hypokalemia. To our knowledge, this is the first case of adrenocortical adenoma presenting with rhabdomyolysis in a child.

Coexistence of Aldosterone-Producing Adrenocortical Adenoma and Pheochromocytoma in an Ipsilateral Adrenal Gland

A 40-year-old female, diagnosed as essential hypertension, demonstrated a 2 cm mass in left adrenal gland by computed tomography without abnormal endocrinological findings. (131)I-adosterol and (123)I-metaiodobenzylguanidine (MIBG) scintigraphy at 39 years of age showed no abnormal accumulation. Follow up (131)I-adosterol scintigraphy performed one year later showed apparently abnormal uptake and slightly elevated uptake in left adrenal gland. Her physical examination was unremarkable except for mild hypertension. Routine blood chemistry was normal except for hypokalemia. Endocrinological date revealed suppressed plasma renin activity, and elevated plasma aldosterone concentration, and noradrenalin levels. Serial T2-weighted magnetic resonance imaging clearly demonstrated two distinct tumors. Furthermore, selective adrenal venous sampling with intravenous ACTH infusion indicated aldosterone-producing adrenocortical adenoma (APA) in left adrenal gland. During operation of adrenal tumor, blood pressure elevated markedly and complication of pheochromocytoma (PC) was suspected. Immunohistochemical findings after left adrenolectomy revealed that the adrenal mass was compatible with APA and PC. Risk of operation against undiagnosed PC is very high and, therefore, it must be diagnosed before surgery. Herein, we present an extremely rare case of the simultaneous occurrence of both APA and PC in an ipsilateral adrenal gland.

46,XY agonadism associated with adrenal adenoma/myelolipoma: report of a case analyzing Y-chromosome-specific sequences

A unique patient with 46,XY agonadism associated with adrenal adenoma/myelolipoma is described. The patient was an 18-year-old female with primary amenorrhea, lack of secondary sexual development and an aldosterone-producing adrenocortical adenoma associated with foci of myelolipoma. Molecular analyses of Y-chromosome-specific regions, including automated sequencing of the entire coding region of SRY, the Y-linked testis-determining gene, were performed. Our results excluded the possibility that a mutation in SRY was responsible for this unusual clinical combination.

Genetic alterations in patients with primary aldosteronism.

The syndrome of primary aldosteronism is characterized by hypertension with excessive production of aldosterone, potassium loss, and suppression of the renin-angiotensin system. The most common clinical subtypes of primary aldosteronism are aldosterone-producing adrenocortical adenoma (APA) and bilateral adrenal cortical hyperplasia (idiopathic hyperaldosteronism, or IHA). It has been reported that renin suppression and aldosterone levels are lower and hypokalemia milder in patients with IHA than in patients with APA. In the present study, we investigated the genetic analysis of aldosterone synthase gene, CYP11B2 in patients with primary aldosteronism and review the recent studies. The chimeric CYP11B1/CYP11B2 gene, which is a candidate gene for glucocorticoid-remediable hyperaldosteronism, was not found in either the DNA from aldosteronoma or in the genomic DNA from patients with APA or IHA. Mutations in the CYP21 or CYP11B1 gene were not present in patients with APA. No mutations in the coding region of the CYP11B2 gene were found in patients with IHA or APA. The level of CYP11B2 messenger RNA (mRNA) was much higher in the aldosteronoma portion than in nonadenomatous portion. The overexpression of CYP11B2 mRNA seen in the mononuclear leukocytes of patients with IHA suggests that unidentified aldosterone-stimulating factors or abnormalities of the CYP11B2 promoter region may cause the overproduction of aldosterone characteristic of IHA. The variants of the CYP11B2 gene may also contribute to dysregulation of aldosterone synthesis and lead to susceptibility to IHA.

A Case of Aldosterone-Producing Adrenocortical Adenoma Associated with Preclinical Cushing's Syndrome and Hypersecretion of Parathyroid Hormone.

A rare case of aldosterone-producing adrenocortical adenoma with preclinical Cushing's syndrome and hypersecretion of parathyroid hormone (PTH) is described. A 64-year-old male patient had a history of hypertension for two decades and hypokalemia for 4 years. He suffered from left hemiparesis and aphasia due to cerebral hemorrhage, but his appearance was not Cushingoid. His plasma renin activity was below the normal range, while plasma aldosterone concentration was high. They did not respond to furosemide-upright test. His plasma cortisol level in the morning was at the upper limit of the normal range, but it did not show a diurnal rhythm nor was it suppressed by 1 mg and 8 mg of dexamethasone. Computed tomography showed a low density tumor in the right adrenal gland. An adrenal scintigram under dexamethasone treatment revealed an uptake of the tracer on the right side, and plasma aldosterone and cortisol concentrations in the adrenal vein were higher on the right side than on the opposite. The diagnosis of right aldosterone-producing adrenal adenoma with an autonomous production of cortisol was confirmed by right adrenalectomy. Histological findings showed an adenoma consisting mostly of clear cells, but that the nests of compact cells were scattered. Analysis of an extract from the adenoma revealed that the adenoma contained an excess amount of aldosterone and that the cortisol/corticosterone ratio was higher than that of aldosterone-producing adenoma. Both serum calcium and PTH levels remained high one year after adrenalectomy. Ultrasonography revealed the swelling of a parathyroid gland on the left side, indicating the coexistence of an autonomous hyperparathyroidism.

Primary Aldosteronism in a Patient With Familial Adenomatous Polyposis

Patients with familial adenomatous polyposis (FAP) frequently have extracolonic manifestations of their disease. Prior reports have indicated an increased prevalence of adrenal lesions in patients with FAP. Although most of the adrenal lesions represent nonfunctioning adenomas, some patients have had hypercortisolism due to adrenocortical carcinoma or bilateral nodular hyperplasia. We present a case of a patient with FAP who had mineralocorticoid excess due to an aldosterone-producing adrenocortical adenoma.

Gene expression and roles of angiotensin II type 1 and type 2 receptors in human adrenals.

Although stimulation of aldosterone secretion is one of the functions of angiotensin II, the gene expression and biological significance of the angiotensin II receptor subtypes, AT1 and AT2, in the human adrenal have not been characterized. We therefore investigated the transcription levels of the receptor subtype genes and their roles in regulation of steroid secretion by human adrenals. The expression of AT1 and AT2 receptor mRNA was assessed by reverse transcription-polymerase chain reaction followed by Southern blot analysis in normal adrenocortical tissues (n = 6) and a series of adrenal tumour tissues: aldosterone-producing adrenocortical adenoma (n=6), Cushing's syndrome (n = 6) and pheochromocytoma (n = 6). The role of the two receptor subtypes in steroid secretion in vitro was examined by incubating the tissue with angiotensin II(1 microM) with or without the selective AT1 antagonist CV-11974 (1 microM). Both AT1 and AT2 receptor mRNA transcripts were demonstrated in all of the human adrenal tissues tested. Angiotensin II-induced aldosterone secretion was suppressed 50% upon the addition of CV-11974. The selective AT2 agonist CGP-42112 increased aldosterone secretion by 55% over the control, which was not suppressed by CV-11974. Angiotensin II and CGP-42112 did not affect cortisol secretion. These results suggest that both AT2 and AT1 receptors may be involved in the regulation of aldosterone secretion and tumorigenesis of the human adrenals.

Primary aldosteronism in a patient with an aldosterone-producing adenoma

We describe an unusual patient presenting with a history of refractory hypertension and hypokalemia. Initial screening tests for adrenal hypertension were consistent with primary aldosteronism and an abdominal computed tomography scan showed an 8-mm left adrenal mass. However, adrenal venous sampling revealed markedly suppressed plasma aldosterone in the left adrenal vein but increased plasma aldosterone in the right adrenal vein. Therefore, on the basis of the clinical, radiographic, and laboratory findings, we concluded that the patient had a nonfunctioning adrenocortical adenoma on the left and an aldosterone-producing adrenocortical adenoma on the right, with the aldosteronoma resulting in hypertension and hypokalemia. Right adrenalectomy decreased the hypertension and corrected the hypokalemia. The right adrenal contained a 7-mm nodule microscopically consistent with the diagnosis of a cortical adenoma. The case highlights key steps and potential pitfalls in the evaluation of adrenal hypertension.