Constitutive beta-catenin activation induces adrenal hyperplasia and promotes adrenal cancer development

Chronic activation of adrenal Gq signaling induces Cyp11b2 expression in the zona fasciculata and hyperaldosteronism

Hyperaldosteronism is often associated with inappropriate aldosterone production and aldosterone synthase (Cyp11b2) expression. Normally, Cyp11b2 expression is limited to the adrenal zona glomerulosa (ZG) and regulated by angiotensin II which signals through Gq protein-coupled receptors. As cells migrate inwards, they differentiate into 11β-hydroxylase-expressing zona fasciculata (ZF) cells lacking Cyp11b2. The mechanism causing ZG-specific aldosterone biosynthesis is still unclear. We investigated the effect of chronic Gq signaling using transgenic mice with a clozapine N-oxide (CNO)-activated human M3 muscarinic receptor (DREADD) coupled to Gq (hM3Dq) that was expressed throughout the adrenal cortex. CNO raised circulating aldosterone in the presence of a high sodium diet with greater response seen in females compared to males. Immunohistochemistry and transcriptomics indicated disrupted zonal Cyp11b2 expression while Wnt signaling remained unchanged. Chronic Gq-DREADD signaling also induced an intra-adrenal RAAS in CNO-treated mice. Chronic Gq signaling disrupted adrenal cortex zonal aldosterone production associated with ZF expression of Cyp11b2.

Prehatching development of the adrenal gland in Japanese quail (Coturnix japonica): Histological, immunohistochemical, and electron microscopic studies

The adrenal glands play a key role in maintaining the physiological balance of birds and helping them to survive environmental changes. The objective of the present work was to give a detailed investigation of the histological, ultrastructural, and immunohistochemical findings of the adrenal gland in Japanese quail during the prehatching phase. The current study was performed on 45 healthy Japanese quail embryos at different prehatching periods. Our results showed the primordium of the quail's adrenocortical tissue appeared at 3 days of incubation as a thickening of the splanchnic mesoderm. The prospective chromaffin cells appeared at 5 days as clusters of cells migrated from the neural crest cells along the dorsal aorta toward the interrenal tissue. TH immunoreactivity was observed in the neural crest cells during their migration toward the adrenal primordium. Furthermore, these TH immunopositive cells were intermingled with the developing interrenal cell cords that developed from the coelomic epithelium. NSE immunostaining was detected within the cytoplasm of interrenal cells, chromaffin cells, and ganglion cells. Sox10 is expressed in chromaffin and ganglion cells with different staining intensities. On the 13th day of prehatching, both interrenal and chromaffin cells were β-catenin immunonegative, but on the 17th day, both cells were immunopositively. Our findings show that during prenatal life, the adrenal gland undergoes significant morphological changes. Together, the present data suggest that studying the prenatal development of the adrenal gland in birds is important for advancing our understanding of this critical organ and its functions. RESEARCH HIGHLIGHTS: The present study aimed to give a detailed study of the histological, ultrastructural, and immunohistochemical investigations of the adrenal gland in Japanese quail during the prehatching period. The interrenal primordium was observed on the third embryonic day, on the fifth ED the primordium of the chromaffin tissue appeared as row of migrating neural crest cell. At the ultrastructural level, the interrenal cells take steroid-secreting cells characters, they have varying amounts of lipid droplets and abundant mitochondria at 15th ED contained moderate number of lysosomes and mitochondria.

Advances in translational research of the rare cancer type adrenocortical carcinoma

Adrenocortical carcinoma is a rare malignancy with an annual worldwide incidence of 1-2 cases per 1 million and a 5-year survival rate of <60%. Although adrenocortical carcinoma is rare, such rare cancers account for approximately one third of patients diagnosed with cancer annually. In the past decade, there have been considerable advances in understanding the molecular basis of adrenocortical carcinoma. The genetic events associated with adrenocortical carcinoma in adults are distinct from those of paediatric cases, which are often associated with germline or somatic TP53 mutations and have a better prognosis. In adult primary adrenocortical carcinoma, the main somatic genetic alterations occur in genes that encode proteins involved in the WNT-β-catenin pathway, cell cycle and p53 apoptosis pathway, chromatin remodelling and telomere maintenance pathway, cAMP-protein kinase A (PKA) pathway or DNA transcription and RNA translation pathways. Recently, integrated molecular studies of adrenocortical carcinomas, which have characterized somatic mutations and the methylome as well as gene and microRNA expression profiles, have led to a molecular classification of these tumours that can predict prognosis and have helped to identify new therapeutic targets. In this Review, we summarize these recent translational research advances in adrenocortical carcinoma, which it is hoped could lead to improved patient diagnosis, treatment and outcome.

Post-hatching developmental changes in the adrenal gland of the Japanese quail (Coturnix coturnix japonica): Histological, immunohistochemical, and electron microscopic studies

The adrenal glands are paired abdominal endocrine organs vital to the bird's health. The present research aimed to provide a comprehensive examination of the histological, ultrastructural, and immunohistochemical investigations of the adrenal gland in Japanese quail during the post hatching period. The current study was performed on 21 healthy Japanese quail chicks at different post hatching periods. Our results showed the adrenal gland is surrounded by a connective tissue capsule, which consists of dense collagen fibers containing large blood vessels, chromaffin cells, autonomic ganglia, fibroblasts, and migrating Schwann cells. The zonation of the adrenal gland is composed of a subcapsular layer, a peripheral zone, and a central zone, which gets more pronounced with age. At the ultrastructural level, the interrenal cells take the steroid-secreting cells characters; they have varying amounts of lipid droplets and abundant mitochondria. Adrenal medullary chromaffin cells showed positive immunoreactivity to the NSE. With increasing age, the chromaffin tissue's Sox10 immunoreactivity increased. β-catenin is expressed within the plasmalemma and the cytoplasm of the interrenal and chromaffin cells and its reactivity increased with age, especially in the chromaffin cells. Our results indicate the adrenal gland undergoes significant morphological changes during the postnatal life. Overall, the postnatal period is an important time for the development and maturation of the adrenal glands.

Age-related Changes in the Adrenal Cortex: Insights and Implications

Aging is characterized by a gradual decline in physiological function. This process affects all organs including the adrenal cortex, which normally functions to produce essential steroid hormones including mineralocorticoids, glucocorticoids, and androgens. With increasing age, features such as reduced adrenal cortex size, altered zonation, and increased myeloid immune cell infiltration substantially alter the structure and function of the adrenal cortex. Many of these hallmark features of adrenal cortex aging occur both in males and females, yet are more enhanced in males. Hormonally, a substantial reduction in adrenal androgens is a key feature of aging, which is accompanied by modest changes in aldosterone and cortisol. These hormonal changes are associated with various pathological consequences including impaired immune responses, decreased bone health, and accelerated age-related diseases. One of the most notable changes with adrenal aging is the increased incidence of adrenal tumors, which is sex dimorphic with a higher prevalence in females. Increased adrenal tumorigenesis with age is likely driven by both an increase in genetic mutations as well as remodeling of the tissue microenvironment. Novel antiaging strategies offer a promising avenue to mitigate adrenal aging and alleviate age-associated pathologies, including adrenal tumors.

Targeting Oncogenic Wnt/β-Catenin Signaling in Adrenocortical Carcinoma Disrupts ECM Expression and Impairs Tumor Growth

Adrenocortical carcinoma (ACC) is a rare but highly aggressive cancer with limited treatment options and poor survival for patients with advanced disease. An improved understanding of the transcriptional programs engaged in ACC will help direct rational, targeted therapies. Whereas activating mutations in Wnt/β-catenin signaling are frequently observed, the β-catenin-dependent transcriptional targets that promote tumor progression are poorly understood. To address this question, we analyzed ACC transcriptome data and identified a novel Wnt/β-catenin-associated signature in ACC enriched for the extracellular matrix (ECM) and predictive of poor survival. This suggested an oncogenic role for Wnt/β-catenin in regulating the ACC microenvironment. We further investigated the minor fibrillar collagen, collagen XI alpha 1 (COL11A1), and found that COL11A1 expression originates specifically from cancer cells and is strongly correlated with both Wnt/β-catenin activation and poor patient survival. Inhibition of constitutively active Wnt/β-catenin signaling in the human ACC cell line, NCI-H295R, significantly reduced the expression of COL11A1 and other ECM components and decreased cancer cell viability. To investigate the preclinical potential of Wnt/β-catenin inhibition in the adrenal microenvironment, we developed a minimally invasive orthotopic xenograft model of ACC and demonstrated that treatment with the newly developed Wnt/β-catenin:TBL1 inhibitor Tegavivint significantly reduced tumor growth. Together, our data support that the inhibition of aberrantly active Wnt/β-catenin disrupts transcriptional reprogramming of the microenvironment and reduces ACC growth and survival. Furthermore, this β-catenin-dependent oncogenic program can be therapeutically targeted with a newly developed Wnt/β-catenin inhibitor. These results show promise for the further clinical development of Wnt/β-catenin inhibitors in ACC and unveil a novel Wnt/β-catenin-regulated transcriptome.

Senescence-induced immune remodeling facilitates metastatic adrenal cancer in a sex-dimorphic manner

Aging markedly increases cancer risk, yet our mechanistic understanding of how aging influences cancer initiation is limited. Here we demonstrate that the loss of ZNRF3, an inhibitor of Wnt signaling that is frequently mutated in adrenocortical carcinoma, leads to the induction of cellular senescence that remodels the tissue microenvironment and ultimately permits metastatic adrenal cancer in old animals. The effects are sexually dimorphic, with males exhibiting earlier senescence activation and a greater innate immune response, driven in part by androgens, resulting in high myeloid cell accumulation and lower incidence of malignancy. Conversely, females present a dampened immune response and increased susceptibility to metastatic cancer. Senescence-recruited myeloid cells become depleted as tumors progress, which is recapitulated in patients in whom a low myeloid signature is associated with worse outcomes. Our study uncovers a role for myeloid cells in restraining adrenal cancer with substantial prognostic value and provides a model for interrogating pleiotropic effects of cellular senescence in cancer.

Preclinical Models of Adrenocortical Cancer

Adrenocortical cancer is an aggressive endocrine malignancy with an incidence of 0.72 to 1.02 per million people/year, and a very poor prognosis with a five-year survival rate of 22%. As an orphan disease, clinical data are scarce, meaning that drug development and mechanistic research depend especially on preclinical models. While a single human ACC cell line was available for the last three decades, over the last five years, many new in vitro and in vivo preclinical models have been generated. Herein, we review both in vitro (cell lines, spheroids, and organoids) and in vivo (xenograft and genetically engineered mouse) models. Striking leaps have been made in terms of the preclinical models of ACC, and there are now several modern models available publicly and in repositories for research in this area.

New advances in endocrine hypertension: from genes to biomarkers

Hypertension (HT) is a major cardiovascular risk factor that affects 10% to 40% of the general population in an age-dependent manner. Detection of secondary forms of HT is particularly important because it allows the targeted management of the underlying disease. Among hypertensive patients, the prevalence of endocrine HT reaches up to 10%. Adrenal diseases are the most frequent cause of endocrine HT and are associated with excess production of mineralocorticoids (mainly primary aldosteronism), glucocorticoids (Cushing syndrome), and catecholamines (pheochromocytoma). In addition, a few rare diseases directly affecting the action of mineralocorticoids and glucocorticoids in the kidney also lead to endocrine HT. Over the past years, genomic and genetic studies have allowed improving our knowledge on the molecular mechanisms of endocrine HT. Those discoveries have opened new opportunities to transfer knowledge to clinical practice for better diagnosis and specific treatment of affected subjects. In this review, we describe the physiology of adrenal hormone biosynthesis and action, the clinical and biochemical characteristics of different forms of endocrine HT, and their underlying genetic defects. We discuss the impact of these discoveries on diagnosis and management of patients, as well as new perspectives related to the use of new biomarkers for improved patient care.

Loss of LGR4/GPR48 causes severe neonatal salt wasting due to disrupted WNT signaling altering adrenal zonation

Disorders of isolated mineralocorticoid deficiency, which cause potentially life-threatening salt-wasting crisis early in life, have been associated with gene variants of aldosterone biosynthesis or resistance; however, in some patients no such variants are found. WNT/β-catenin signaling is crucial for differentiation and maintenance of the aldosterone-producing adrenal zona glomerulosa (zG). Herein, we describe a highly consanguineous family with multiple perinatal deaths and infants presenting at birth with failure to thrive, severe salt-wasting crises associated with isolated hypoaldosteronism, nail anomalies, short stature, and deafness. Whole exome sequencing revealed a homozygous splice variant in the R-SPONDIN receptor LGR4 gene (c.618-1G>C) regulating WNT signaling. The resulting transcripts affected protein function and stability and resulted in loss of Wnt/β-catenin signaling in vitro. The impact of LGR4 inactivation was analyzed by adrenal cortex-specific ablation of Lgr4, using Lgr4fl/fl mice mated with Sf1:Cre mice. Inactivation of Lgr4 within the adrenal cortex in the mouse model caused decreased WNT signaling, aberrant zonation with deficient zG, and reduced aldosterone production. Thus, human LGR4 mutations establish a direct link between LGR4 inactivation and decreased canonical WNT signaling, which results in abnormal zG differentiation and endocrine function. Therefore, variants in WNT signaling and its regulators should systematically be considered in familial hyperreninemic hypoaldosteronism.

A case of adrenocortical carcinoma diagnosed 9 years after the discovery of adrenal incidentaloma

Adrenocortical carcinoma (ACC) is an uncommon cause of adrenal incidentaloma (AI). ACCs generally occur in large sizes, >4 cm in diameter, at initial presentation and grow rapidly. Therefore, there have been few reports of cases with long-term follow-up with imaging before ACC was diagnosed. Herein, we present a case of an adrenal mass that had remained small and unchanged for 5 years but later grew rapidly and was finally diagnosed as ACC. A 77-year-old hypertensive woman was referred to our hospital for the examination of a 5.4-cm left adrenal mass. Upon reviewing her previous unenhanced computed tomography (CT) scan, a 1.6-cm and 30 Hounsfield units (HU), homogeneous, round, left adrenal mass was incidentally detected 9 years ago. This mass remained unchanged until 4 years ago. One year ago, the mass enlarged to 3.0-cm and changed into an irregular form with heterogeneous density. The hormonal evaluation during the 9 years from the discovery of the AI was inadequate. The present examination diagnosed this case as ACC with subclinical Cushing's syndrome. The patient underwent laparoscopic left adrenalectomy, and a histological diagnosis of high-grade ACC was made. The resected tumor had the CTNNB1 gene mutation. High unenhanced CT attenuation values (>10 HU) are one of the findings that raise suspicion of malignancy. This case suggests that patients with findings atypical of adenomas on an initial unenhanced CT might be carefully followed up given the possibility of development of ACCs, even if the initial tumor size is small.

Loss of SUMO-specific protease 2 causes isolated glucocorticoid deficiency by blocking adrenal cortex zonal transdifferentiation in mice

SUMOylation is a dynamic posttranslational modification, that provides fine-tuning of protein function involved in the cellular response to stress, differentiation, and tissue development. In the adrenal cortex, an emblematic endocrine organ that mediates adaptation to physiological demands, the SUMOylation gradient is inversely correlated with the gradient of cellular differentiation raising important questions about its role in functional zonation and the response to stress. Considering that SUMO-specific protease 2 (SENP2), a deSUMOylating enzyme, is upregulated by Adrenocorticotropic Hormone (ACTH)/cAMP-dependent Protein Kinase (PKA) signalling within the zona fasciculata, we generated mice with adrenal-specific Senp2 loss to address these questions. Disruption of SENP2 activity in steroidogenic cells leads to specific hypoplasia of the zona fasciculata, a blunted reponse to ACTH and isolated glucocorticoid deficiency. Mechanistically, overSUMOylation resulting from SENP2 loss shifts the balance between ACTH/PKA and WNT/β-catenin signalling leading to repression of PKA activity and ectopic activation of β-catenin. At the cellular level, this blocks transdifferentiation of β-catenin-positive zona glomerulosa cells into fasciculata cells and sensitises them to premature apoptosis. Our findings indicate that the SUMO pathway is critical for adrenal homeostasis and stress responsiveness.

Update on Biology and Genomics of Adrenocortical Carcinomas: Rationale for Emerging Therapies

The adrenal glands are paired endocrine organs that produce steroid hormones and catecholamines required for life. Adrenocortical carcinoma (ACC) is a rare and often fatal cancer of the peripheral domain of the gland, the adrenal cortex. Recent research in adrenal development, homeostasis, and disease have refined our understanding of the cellular and molecular programs controlling cortical growth and renewal, uncovering crucial clues into how physiologic programs are hijacked in early and late stages of malignant neoplasia. Alongside these studies, genome-wide approaches to examine adrenocortical tumors have transformed our understanding of ACC biology, and revealed that ACC is composed of distinct molecular subtypes associated with favorable, intermediate, and dismal clinical outcomes. The homogeneous transcriptional and epigenetic programs prevailing in each ACC subtype suggest likely susceptibility to any of a plethora of existing and novel targeted agents, with the caveat that therapeutic response may ultimately be limited by cancer cell plasticity. Despite enormous biomedical research advances in the last decade, the only potentially curative therapy for ACC to date is primary surgical resection, and up to 75% of patients will develop metastatic disease refractory to standard-of-care adjuvant mitotane and cytotoxic chemotherapy. A comprehensive, integrated, and current bench-to-bedside understanding of our field's investigations into adrenocortical physiology and neoplasia is crucial to developing novel clinical tools and approaches to equip the one-in-a-million patient fighting this devastating disease.

Transgenic Mouse Models to Study the Development and Maintenance of the Adrenal Cortex

The cortex of the adrenal gland is organized into concentric zones that produce distinct steroid hormones essential for body homeostasis in mammals. Mechanisms leading to the development, zonation and maintenance of the adrenal cortex are complex and have been studied since the 1800s. However, the advent of genetic manipulation and transgenic mouse models over the past 30 years has revolutionized our understanding of these mechanisms. This review lists and details the distinct Cre recombinase mouse strains available to study the adrenal cortex, and the remarkable progress total and conditional knockout mouse models have enabled us to make in our understanding of the molecular mechanisms regulating the development and maintenance of the adrenal cortex.

Animal Models of Cushing's Syndrome

Endogenous Cushing's syndrome is characterized by unique clinical features and comorbidities, and progress in the analysis of its genetic pathogenesis has been achieved. Moreover, prescribed glucocorticoids are also associated with exogenous Cushing's syndrome. Several animal models have been established to explore the pathophysiology and develop treatments for Cushing's syndrome. Here, we review recent studies reporting animal models of Cushing's syndrome with different features and complications induced by glucocorticoid excess. Exogenous corticosterone (CORT) administration in drinking water is widely utilized, and we found that CORT pellet implantation in mice successfully leads to a Cushing's phenotype. Corticotropin-releasing hormone overexpression mice and adrenal-specific Prkar1a-deficient mice have been developed, and AtT20 transplantation methods have been designed to examine the medical treatments for adrenocorticotropic hormone-producing pituitary neuroendocrine tumors. We also review recent advances in the molecular pathogenesis of glucocorticoid-induced complications using animal models.

Wnt/β-catenin signaling in the adrenal glands of rats in various types of experimental hypertension

Wnt/β-catenin signaling plays a key role in maintaining homeostasis, which is disturbed in hypertension. Taking into account the lack of literature describing changes in the Wnt/β-catenin pathway in the adrenal glands under conditions of elevated arterial pressure, here we compare the expression of WNT4, WNT10A, β-catenin, and GSK-3β in the adrenal glands of hypertensive rats of various etiologies. The studies were carried out on the adrenal glands of rats with spontaneous hypertension (SHR), renalvascular (2K1C), and deoxycorticosterone acetate (DOCA)-salt. Immunohistochemical and PCR methods were used to identify the molecular components of the canonical signaling pathway and to evaluate gene expression. Immunoreactivity and expression of WNT4, WNT10A, β-catenin, and GSK-3β in adrenals of SHR was decreased, compared to control rats. In adrenals of 2K1C rats, intensity of immunohistochemical reaction and expression of WNT4 and β-catenin was lower, while immunoreactivity and expression of WNT10A and GSK-3β were higher, compared to normotensive animals. Significantly stronger immunoreaction and expression of WNT4, β-catenin and GSK-3β but weaker immunoreactivity and expression of WNT10A were noted in adrenals in DOCA-salt rats, compared to control rats. In conclusion, our data provide new molecular information indicating that the canonical WNT pathway is disrupted in the adrenal glands of hypertensive rats. They show that the dysregulation of the WNT pathway depends on the etiology of hypertension.

Pathophysiology and histopathology of primary aldosteronism

Primary aldosteronism (PA) can be sporadic or familial and classified into unilateral and bilateral forms. Sporadic PA predominates with excessive aldosterone production usually arising from a unilateral aldosterone-producing adenoma (APA) or bilateral adrenocortical hyperplasia. Familial PA is rare and caused by germline variants, that partly correspond to somatic alterations in APAs. Classification into unilateral and bilateral PA determines the treatment approach but does not accurately mirror disease pathology. Some evidence indicates a disease continuum ranging from balanced aldosterone production from each adrenal to extreme asymmetrical bilateral aldosterone production. Nonetheless, surgical removal of the overactive adrenal in unilateral PA achieves highly successful outcomes and almost all patients are biochemically cured of their aldosteronism.

Primary aldosteronism: Pathophysiological mechanisms of cell death and proliferation

Primary aldosteronism is the most common surgically curable form of hypertension. The sporadic forms of the disorder are usually caused by aldosterone overproduction from a unilateral adrenocortical aldosterone-producing adenoma or from bilateral adrenocortical hyperplasia. The main knowledge-advances in disease pathophysiology focus on pathogenic germline and somatic variants that drive the excess aldosterone production. Less clear are the molecular and cellular mechanisms that lead to an increased mass of the adrenal cortex. However, the combined application of transcriptomics, metabolomics, and epigenetics has achieved substantial insight into these processes and uncovered the evolving complexity of disrupted cell growth mechanisms in primary aldosteronism. In this review, we summarize and discuss recent progress in our understanding of mechanisms of cell death, and proliferation in the pathophysiology of primary aldosteronism.

Familial Hyperaldosteronism Type 3 with a Rapidly Growing Adrenal Tumor: An In Situ Aldosterone Imaging Study

Primary aldosteronism is most often caused by aldosterone-producing adenoma (APA) and bi-lateral adrenal hyperplasia. Most APAs are caused by somatic mutations of various ion channels and pumps, the most common being the inward-rectifying potassium channel KCNJ5. Germ line mutations of KCNJ5 cause familial hyperaldosteronism type 3 (FH3), which is associated with severe hyperaldosteronism and hypertension. We present an unusual case of FH3 in a young woman, first diagnosed with primary aldosteronism at the age of 6 years, with bilateral adrenal hyperplasia, who underwent unilateral adrenalectomy (left adrenal) to alleviate hyperaldosteronism. However, her hyperaldosteronism persisted. At the age of 26 years, tomography of the remaining adrenal revealed two different adrenal tumors, one of which grew substantially in 4 months; therefore, the adrenal gland was removed. A comprehensive histological, immunohistochemical, and molecular evaluation of various sections of the adrenal gland and in situ visualization of aldosterone, using matrix-assisted laser desorption/ionization imaging mass spectrometry, was performed. Aldosterone synthase (CYP11B2) immunoreactivity was observed in the tumors and adrenal gland. The larger tumor also harbored a somatic β-catenin activating mutation. Aldosterone visualized in situ was only found in the subcapsular regions of the adrenal and not in the tumors. Collectively, this case of FH3 presented unusual tumor development and histological/molecular findings.

Adrenal Cortex Development and Maintenance: Knowledge Acquired From Mouse Models

The adrenal cortex is an endocrine organ organized into concentric zones that are specialized to produce specific steroid hormones essential for life. The development and maintenance of the adrenal cortex are complex, as a fetal adrenal is first formed from a common primordium with the gonads, followed by its separation in a distinct primordium, the invasion of the adrenal primordium by neural crest-derived cells to form the medulla, and finally its encapsulation. The fetal cortex is then replaced by a definitive cortex, which will establish zonation and be maintained throughout life by regeneration relying on the proliferation, centripetal migration, and differentiation of several stem/progenitor cell populations whose activities are sex-specific. Here, we highlight the advances made, using transgenic mouse models, to delineate the molecular mechanisms regulating these processes.

Dichlorodiphenyltrichloroethane and the Adrenal Gland: From Toxicity to Endocrine Disruption

Endocrine disruptors are exogenous compounds that pollute the environment and have effects similar to hormones when inside the body. One of the most widespread endocrine disruptors in the wild is the pesticide dichlorodiphenyltrichloroethane (DDT). Toxic doses of DDT are known to cause cell atrophy and degeneration in the adrenal zona fasciculata and zona reticularis. Daily exposure in a developing organism to supposedly non-toxic doses of DDT have been found to impair the morphogenesis of both the cortex and the medulla of the adrenal glands, as well as disturbing the secretion of hormones in cortical and chromaffin cells. Comparison of high and very low levels of DDT exposure revealed drastic differences in the morphological and functional changes in the adrenal cortex. Moreover, the three adrenocortical zones have different levels of sensitivity to the disruptive actions of DDT. The zona glomerulosa and zona reticularis demonstrate sensitivity to both high and very low levels of DDT in prenatal and postnatal periods. In contrast, the zona fasciculata is less damaged by low (supposedly non-toxic) exposure to DDT and its metabolites but is affected by toxic levels of exposure; thus, DDT exerts both toxic and disruptive effects on the adrenal glands, and sensitivity to these two types of action varies in adrenocortical zones. Disruptive low-dose exposure leads to more severe affection of the adrenal function.

Steroidogenic cell microenvironment and adrenal function in physiological and pathophysiological conditions

The human adrenal cortex is a complex organ which is composed of various cell types including not only steroidogenic cells but also mesenchymal cells, immunocompetent cells and neurons. Intermingling of these diverse cell populations favors cell-to-cell communication processes involving local release of numerous bioactive signals such as biogenic amines, cytokines and neuropeptides. The resulting paracrine interactions play an important role in the regulation of adrenocortical cell functions both in physiological and pathophysiological conditions. Especially, recent evidence indicates that adrenocortical cell microenvironment is involved in the pathogenesis of adrenal disorders associated with corticosteroid excess. The paracrine factors involved in these intraadrenal regulatory mechanisms may thus represent valuable targets for future pharmacological treatments of adrenal diseases.

Adrenal cortex renewal in health and disease

Resident progenitor and/or stem cell populations in the adult adrenal cortex enable cortical cells to undergo homeostatic renewal and regeneration after injury. Renewal occurs predominantly in the outer layers of the adrenal gland but newly formed cells undergo centripetal migration, differentiation and lineage conversion in the process of forming the different functional steroidogenic zones. Over the past 10 years, advances in the genetic characterization of adrenal diseases and studies of mouse models with altered adrenal phenotypes have helped to elucidate the molecular pathways that regulate adrenal tissue renewal, several of which are fine-tuned via complex paracrine and endocrine influences. Moreover, the adrenal gland is a sexually dimorphic organ, and testicular androgens have inhibitory effects on cell proliferation and progenitor cell recruitment in the adrenal cortex. This Review integrates these advances, including the emerging role of sex hormones, into existing knowledge on adrenocortical cell renewal. An in-depth understanding of these mechanisms is expected to contribute to the development of novel therapies for severe endocrine diseases, for which current treatments are unsatisfactory.

Rosette morphology in zona glomerulosa formation and function

How morphology informs function is a fundamental biological question. Here, we review the morphological features of the adrenal zona glomerulosa (zG), highlighting recent cellular and molecular discoveries that govern its formation. The zG consists of glomeruli enwrapped in a Laminin-β1-enriched basement membrane (BM). Within each glomerulus, zG cells are organized as rosettes, a multicellular structure widely used throughout development to mediate epithelial remodeling, but not often found in healthy adult tissues. Rosettes arise by constriction at a common cellular contact point mediated/facilitated by adherens junctions (AJs). In mice, small, dispersed AJs first appear postnatally and enrich along the entire cell-cell contact around 10 days after birth. Subsequently, these AJ-rich contacts contract, allowing rosettes to form. Concurrently, flat sheet-like domains in the nascent zG, undergo invagination and folding, gradually giving rise to the compact round glomeruli that comprise the adult zG. How these structures impact adrenal function is discussed.

Etoposide Triggers Cellular Senescence by Inducing Multiple Centrosomes and Primary Cilia in Adrenocortical Tumor Cells

Etoposide (ETO) has been used in treating adrenocortical tumor (ACT) cells. Our previous study showed that ETO inhibits ACT cell growth. In the present study, we show that ETO treatment at IC50 (10 μM) inhibited ACT cell growth by inducing cellular senescence rather than apoptosis. Several markers of cellular senescence, including enlarged nuclei, activated senescence-associated β-galactosidase activity, elevated levels of p53 and p21, and down-regulation of Lamin B1, were observed. We further found that ETO induced multiple centrosomes. The inhibition of multiple centrosomes accomplished by treating cells with either roscovitine or centrinone or through the overexpression of NR5A1/SF-1 alleviated ETO-induced senescence, suggesting that ETO triggered senescence via multiple centrosomes. Primary cilia also played a role in ETO-induced senescence. In the mechanism, DNA-PK-Chk2 signaling was activated by ETO treatment; inhibition of this signaling cascade alleviated multiple ETO-induced centrosomes and primary cilia followed by reducing cellular senescence. In addition to DNA damage signaling, autophagy was also triggered by ETO treatment for centrosomal events and senescence. Importantly, the inactivation of DNA-PK-Chk2 signaling reduced ETO-triggered autophagy; however, the inhibition of autophagy did not affect DNA-PK-Chk2 activation. Thus, ETO activated the DNA-PK-Chk2 cascade to facilitate autophagy. The activated autophagy further induced multiple centrosomes and primary cilia followed by triggering senescence.

Inhibition of Aurora kinase A activity enhances the antitumor response of beta-catenin blockade in human adrenocortical cancer cells

Adrenocortical cancer (ACC) is a rare and aggressive type of endocrine tumor with high risk of recurrence and metastasis. The overall survival of patients diagnosed with ACC is low and treatment for metastatic stages remain limited to mitotane, which has low efficiency in advanced stages of the disease and is associated with high toxicity. Therefore, identification of new biological targets to improve ACC treatment is crucial. Blockade of the Wnt/beta-catenin pathway decreased adrenal steroidogenesis and increased apoptosis of NCI-H295 human ACC cells, in vitro and in a xenograft mouse model. Aurora kinases play important roles in cell division during the G1-M phase and their aberrant expression is correlated with a poor prognosis in different types of tumors. Hence, we hypothesized that inhibition of aurora kinases activity combined with the beta-catenin pathway blockade would improve the impairment of ACC cell growth in vitro. We studied the combinatorial effects of AMG 900, an aurora kinase inhibitor and PNU-74654, a beta-catenin pathway blocker, on proliferation, survival and tumor progression in multiple ACC cell lines: NCI-H295, CU-ACC1 and CU-ACC2. Exposure of ACC cells to the combination of AMG 900 with PNU-74654 decreased cell proliferation and viability compared to either treatment alone. In addition, AMG 900 inhibited cell invasion and clonogenesis compared to PNU-74654, and the combination showed no greater effects. In contrast, PNU-74654 was more effective in decreasing cortisol secretion. These data suggest that inhibition of aurora kinases activity combined with blockade of the beta-catenin pathway may provide a combinatorial approach for targeting ACC tumors.

Beta-Catenin Causes Adrenal Hyperplasia by Blocking Zonal Transdifferentiation

Activating mutations in the canonical Wnt/β-catenin pathway are key drivers of hyperplasia, the gateway for tumor development. In a wide range of tissues, this occurs primarily through enhanced effects on cellular proliferation. Whether additional mechanisms contribute to β-catenin-driven hyperplasia remains unknown. The adrenal cortex is an ideal system in which to explore this question, as it undergoes hyperplasia following somatic β-catenin gain-of-function (βcat-GOF) mutations. Targeting βcat-GOF to zona Glomerulosa (zG) cells leads to a progressive hyperplastic expansion in the absence of increased proliferation. Instead, we find that hyperplasia results from a functional block in the ability of zG cells to transdifferentiate into zona Fasciculata (zF) cells. Mechanistically, zG cells demonstrate an upregulation of Pde2a, an inhibitor of zF-specific cAMP/PKA signaling. Hyperplasia is further exacerbated by trophic factor stimulation leading to organomegaly. Together, these data indicate that β-catenin drives adrenal hyperplasia through both proliferation-dependent and -independent mechanisms.

Using the adrenal cortex as a model for slow-cycling tissues, Pignatti et al. show that activation of the canonical Wnt/β-catenin pathway leads to tissue hyperplasia by blocking cellular differentiation/cell-fate commitment, independent of its effects on cellular proliferation.

The Sexually Dimorphic Adrenal Cortex: Implications for Adrenal Disease

Many adrenocortical diseases are more prevalent in women than in men, but the reasons underlying this sex bias are still unknown. Recent studies involving gonadectomy and sex hormone replacement experiments in mice have shed some light onto the molecular basis of sexual dimorphism in the adrenal cortex. Indeed, it has been shown that gonadal hormones influence many aspects of adrenal physiology, ranging from stem cell-dependent tissue turnover to steroidogenesis and X-zone dynamics. This article reviews current knowledge on adrenal cortex sexual dimorphism and the potential mechanisms underlying sex hormone influence of adrenal homeostasis. Both topics are expected to contribute to personalized and novel therapeutic approaches in the future.

Adrenal cortex development and related disorders leading to adrenal insufficiency

The adult human adrenal cortex produces steroid hormones that are crucial for life, supporting immune response, glucose homeostasis, salt balance and sexual maturation. It consists of three histologically distinct and functionally specialized zones. The fetal adrenal forms from mesodermal material and produces predominantly adrenal C₁₉ steroids from its fetal zone, which involutes after birth. Transition to the adult cortex occurs immediately after birth for the formation of the zona glomerulosa and fasciculata for aldosterone and cortisol production and continues through infancy until the zona reticularis for adrenal androgen production is formed with adrenarche. The development of this indispensable organ is complex and not fully understood. This article gives an overview of recent knowledge gained of adrenal biology from two perspectives: one, from basic science studying adrenal development, zonation and homeostasis; and two, from adrenal disorders identified in persons manifesting with various isolated or syndromic forms of primary adrenal insufficiency.

Update on Genetics of Primary Aldosteronism

Primary aldosteronism (PA) is the most common form of secondary hypertension, with a prevalence of 5–10% among patients with hypertension. PA is mainly classified into two subtypes: aldosterone-producing adenoma (APA) and bilateral idiopathic hyperaldosteronism. Recent developments in genetic analysis have facilitated the discovery of mutations in KCNJ5, ATP1A1, ATP2B3, CACNA1D, CACNA1H, CLCN2, and CTNNB1 in sporadic or familial forms of PA in the last decade. These findings have greatly advanced our understanding of the mechanism of excess aldosterone synthesis, particularly in APA. Most of the causative genes encode ion channels or pumps, and their mutations lead to depolarization of the cell membrane due to impairment of ion transport. Depolarization activates voltage-gated Ca²⁺ channels and intracellular calcium signaling and promotes the transcription of aldosterone synthase, resulting in overproduction of aldosterone. In this article, we review recent findings on the genetic and molecular mechanisms of PA.

Developmental mechanisms of adrenal cortex formation and their links with adult progenitor populations

The adrenal cortex is the main steroid producing organ of the human body. Studies on adrenal tissue renewal have been neglected for many years, but recent intensified research has seen tremendous progress in our understanding of the formation and homeostasis of this organ. However, cell turnover of the adrenal cortex appears to be complex and several cell populations have been identified that can differentiate into steroidogenic cells and contribute to adrenal cortex renewal. The purpose of this review is to provide an overview of how the adrenal cortex develops and how stem cell populations relate to its developmental progenitors. Finally, we will summarize present and future approaches to harvest the potential of progenitor/stem cells for future cell replacement therapies.

Flow-dependent differentiation of cultured adrenal cells under different stimuli

It still remains unclear how the functional organisation of the adrenal cortex arises. One aim of this study was to create a setup which allows for the establishment of a concentration gradient in vitro. This was achieved by a continuous flow of medium through the culture flask which caused differences in glucose and cortisol concentrations as well as in pH values between the sites of inflow and outflow of medium. Using real-time polymerase chain reaction, we found that a continuous supply of 1 ml medium per hour significantly increased the expression of MC2R, CYP11B1 and CYP17A1 genes of NCI-H295R cells in the distal area of the flask as compared with the proximal part. The expression of the AT1R showed a reverse regulation. The addition of dexamethasone to the medium led to an increase in gene expression of MC2R while AT1R was downregulated. Moreover, we detected a higher expression of CYP11B2 and a decreased expression of CYP11B1 when endothelial cell-conditioned medium (ECCM) was added to the inflow. Our experiments show that a directed medium delivery system creates different gradients and affects the functional differentiation of the NCI-H295R cells. Also, our results emphasise that products of endothelial cells have additional effects on the differentiation of the cultured adrenal cortical cells. Our results are in support that the regulation of the adrenal zonation is possible through different concentration gradients.

What Did We Learn from the Molecular Biology of Adrenal Cortical Neoplasia? From Histopathology to Translational Genomics

Approximately one-tenth of the general population exhibit adrenal cortical nodules, and the incidence has increased. Afflicted patients display a multifaceted symptomatology-sometimes with rather spectacular features. Given the general infrequency as well as the specific clinical, histological, and molecular considerations characterizing these lesions, adrenal cortical tumors should be investigated by endocrine pathologists in high-volume tertiary centers. Even so, to distinguish specific forms of benign adrenal cortical lesions as well as to pinpoint malignant cases with the highest risk of poor outcome is often challenging using conventional histology alone, and molecular genetics and translational biomarkers are therefore gaining increased attention as a possible discriminator in this context. In general, our understanding of adrenal cortical tumorigenesis has increased tremendously the last decade, not least due to the development of next-generation sequencing techniques. Comprehensive analyses have helped establish the link between benign aldosterone-producing adrenal cortical proliferations and ion channel mutations, as well as mutations in the protein kinase A (PKA) signaling pathway coupled to cortisol-producing adrenal cortical lesions. Moreover, molecular classifications of adrenal cortical tumors have facilitated the distinction of benign from malignant forms, as well as the prognostication of the individual patients with verified adrenal cortical carcinoma, enabling high-resolution diagnostics that is not entirely possible by histology alone. Therefore, combinations of histology, immunohistochemistry, and next-generation multi-omic analyses are all needed in an integrated fashion to properly distinguish malignancy in some cases. Despite significant progress made in the field, current clinical and pathological challenges include the preoperative distinction of non-metastatic low-grade adrenal cortical carcinoma confined to the adrenal gland, adoption of individualized therapeutic algorithms aligned with molecular and histopathologic risk stratification tools, and histological confirmation of functional adrenal cortical disease in the context of multifocal adrenal cortical proliferations. We herein review the histological, genetic, and epigenetic landscapes of benign and malignant adrenal cortical neoplasia from a modern surgical endocrine pathology perspective and highlight key mechanisms of value for diagnostic and prognostic purposes.

β-catenin in adrenal zonation and disease

The Wnt signaling pathway is a critical mediator of the development and maintenance of several tissues. The adrenal cortex is highly dependent upon Wnt/β-catenin signaling for proper zonation and endocrine function. Adrenocortical cells emerge in the peripheral capsule and subcapsular cortex of the gland as progenitor cells that centripetally differentiate into steroid hormone-producing cells of three functionally distinct concentric zones that respond robustly to various endocrine stimuli. Wnt/β-catenin signaling mediates adrenocortical progenitor cell fate and tissue renewal to maintain the gland throughout life. Aberrant Wnt/β-catenin signaling contributes to various adrenal disorders of steroid production and growth that range from hypofunction and hypoplasia to hyperfunction, hyperplasia, benign adrenocortical adenomas, and malignant adrenocortical carcinomas. Great strides have been made in defining the molecular underpinnings of adrenocortical homeostasis and disease, including the interplay between the capsule and cortex, critical components involved in maintaining the adrenocortical Wnt/β-catenin signaling gradient, and new targets in adrenal cancer. This review seeks to examine these and other recent advancements in understanding adrenocortical Wnt/β-catenin signaling and how this knowledge can inform therapeutic options for adrenal disease.

Pde8b haploinsufficiency in mice is associated with modest adrenal defects, impaired steroidogenesis, and male infertility, unaltered by concurrent PKA or Wnt activation

PDE8B, PRKAR1A and the Wnt/β-catenin signaling are involved in endocrine disorders. However, how PDEB8B interacts with both Wnt and protein kinase A (PKA) signaling in vivo remains unknown. We created a novel Pde8b knockout mouse line (Pde8b-/-); Pde8b haploinsufficient (Pde8b+/-) mice were then crossed with mice harboring: (1) constitutive beta-catenin activation (Pde8b+/-;ΔCat) and (2) Prkar1a haploinsufficieny (Pde8b+/-;Prkar1a+/-). Adrenals and testes from mice (3-12-mo) were evaluated in addition to plasma corticosterone, aldosterone and Dkk3 concentrations, and the examination of expression of steroidogenesis-, Wnt- and cAMP/PKA-related genes. Pde8b-/- male mice were infertile with down-regulation of the Wnt/β-catenin pathway which did not change significantly in the Pde8b+/-;ΔCat mice. Prkar1a haploinsufficiency also did not change the phenotype significantly. In vitro studies showed that PDE8B knockdown upregulated the Wnt pathway and increased proliferation in CTNNB1-mutant cells, whereas it downregulated the Wnt pathway in PRKAR1A-mutant cells. These data support an overall weak, if any, role for PDE8B in adrenocortical tumorigenesis, even when co-altered with Wnt signaling or PKA upregulation; on the other hand, PDE8B appears to play a significant role in male fertility.

Transcription factors β-catenin and Hex in postnatal development of the rat adrenal cortex: implication in proliferation control

Transcriptional regulation of growth, maturation, and cell turnover in adrenal cortex during postnatal development has been significantly less studied than in embryonic period, while elucidation of factors mediating its normal postnatal morphogenesis could clarify mechanisms of tumorigenesis in adrenal cortex. Expression of transcription factors Hex, β-catenin, and Wnt signaling in the adrenal cortex of male pubertal and postpubertal Wistar rats were examined. Adrenal cortex morphology and hormone production during postnatal development were also studied. Adrenocortical zones demonstrated similar reduction of Ki-67-expressing cells, but different patterns of morphological and functional changes. Age-dependent decrease in percentage of cells with membrane localization of β-catenin and stable rate of cells with nuclear β-catenin, indicative of Wnt signaling activation, were revealed in each cortical zone. Nuclear β-catenin was not observed in immature areas of zona fasciculata. No association between Wnt signaling activation and rates of proliferation as well as changes in secretion of adrenocortical hormones was observed in postnatal development of rat adrenal cortex. Hex, known as antiproliferative factor, showed up-regulation of expression after puberty. Strong inverse correlations between ratio of Hex-positive cells and proliferating cells were found in zona glomerulosa and zona fasciculata. Zona reticularis demonstrated moderate correlation. Thus, these findings suggest a role for Hex in proliferation control during postnatal development of the rat adrenal cortex and possible implication of Hex down-regulation in adrenocortical dysplasia and neoplasia, which requires further study. Evaluation of Hex expression may also be considered a potent tool in assessment of cell proliferation in rat adrenal cortex.

Stem cell function and plasticity in the normal physiology of the adrenal cortex

The adrenal cortex functions to produce steroid hormones necessary for life. To maintain its functional capacity throughout life, the adrenal cortex must be continually replenished and rapidly repaired following injury. Moreover, the adrenal responds to endocrine-mediated organismal needs, which are highly dynamic and necessitate a precise steroidogenic response. To meet these diverse needs, the adrenal employs multiple cell populations with stem cell function. Here, we discuss the literature on adrenocortical stem cells using hematopoietic stem cells as a benchmark to examine the functional capacity of particular cell populations, including those located in the capsule and peripheral cortex. These populations are coordinately regulated by paracrine and endocrine signaling mechanisms, and display remarkable plasticity to adapt to different physiological and pathological conditions. Some populations also exhibit sex-specific activity, which contributes to highly divergent proliferation rates between sexes. Understanding mechanisms that govern adrenocortical renewal has broad implications for both regenerative medicine and cancer.

HOX genes promote cell proliferation and are potential therapeutic targets in adrenocortical tumours

Background

Understanding the pathways that drive adrenocortical carcinoma (ACC) is essential to the development of more effective therapies. This study investigates the role of the transcription factor HOXB9 and other HOX factors in ACC and its treatment.

Methods

We used transgenic mouse models to determine the role of Hoxb9 in adrenal tumour development. Patient transcriptomic data was analysed for the expression of HOX genes and their association with disease. Drug response studies on various adrenocortical models were done to establish novel therapeutic options.

Results

Our human ACC dataset analyses showed high expression of HOXB9, and other HOX factors, are associated with poorer prognosis. Transgenic overexpression of Hoxb9 in the adrenal cortex of mice with activated Ctnnb1 led to larger adrenal tumours. This phenotype was preferentially observed in male mice and was characterised by more proliferating cells and an increase in the expression of cell cycle genes, including Ccne1. Adrenal tumour cells were found to be dependent on HOX function for survival and were sensitive to a specific peptide inhibitor.

Conclusions

These studies show Hoxb9 can promote adrenal tumour progression in a sex-dependent manner and have identified HOX factors as potential drug targets, leading to novel therapeutic approaches in ACC.

Key MicroRNA's and Their Targetome in Adrenocortical Cancer

Adrenocortical Carcinoma (ACC) is a rare but aggressive malignancy with poor prognosis and limited response to available systemic therapies. Although complete surgical resection gives the best chance for long-term survival, ACC has a two-year recurrence rate of 50%, which poses a therapeutic challenge. High throughput analyses focused on characterizing the molecular signature of ACC have revealed specific micro-RNAs (miRNAs) that are associated with aggressive tumor phenotypes. MiRNAs are small non-coding RNA molecules that regulate gene expression by inhibiting mRNA translation or degrading mRNA transcripts and have been generally implicated in carcinogenesis. This review summarizes the current insights into dysregulated miRNAs in ACC tumorigenesis, their known functions, and specific targetomes. In addition, we explore the possibility of particular miRNAs to be exploited as clinical biomarkers in ACC and as potential therapeutics.

Chemogenetic activation of adrenocortical Gq signaling causes hyperaldosteronism and disrupts functional zonation

The mineralocorticoid aldosterone is produced in the adrenal zona glomerulosa (ZG) under the control of the renin-angiotensin II (AngII) system. Primary aldosteronism (PA) results from renin-independent production of aldosterone and is a common cause of hypertension. PA is caused by dysregulated localization of the enzyme aldosterone synthase (Cyp11b2), which is normally restricted to the ZG. Cyp11b2 transcription and aldosterone production are predominantly regulated by AngII activation of the Gq signaling pathway. Here, we report the generation of transgenic mice with Gq-coupled designer receptors exclusively activated by designer drugs (DREADDs) specifically in the adrenal cortex. We show that adrenal-wide ligand activation of Gq DREADD receptors triggered disorganization of adrenal functional zonation, with induction of Cyp11b2 in glucocorticoid-producing zona fasciculata cells. This result was consistent with increased renin-independent aldosterone production and hypertension. All parameters were reversible following termination of DREADD-mediated Gq signaling. These findings demonstrate that Gq signaling is sufficient for adrenocortical aldosterone production and implicate this pathway in the determination of zone-specific steroid production within the adrenal cortex. This transgenic mouse also provides an inducible and reversible model of hyperaldosteronism to investigate PA therapeutics and the mechanisms leading to the damaging effects of aldosterone on the cardiovascular system.

Intratumor heterogeneity of prognostic DNA-based molecular markers in adrenocortical carcinoma

BACKGROUND

The prognosis of adrenocortical carcinoma (ACC) is heterogeneous. Genomic studies have identified ACC subgroups characterized by specific molecular alterations, including features measured at DNA level (somatic mutations, chromosome alterations, DNA methylation), which are closely associated with outcome. The aim of this study was to evaluate intratumor heterogeneity of prognostic molecular markers at the DNA level.

METHODS

Two different tissue samples (primary tumor, local recurrence or metastasis) were analyzed in 26 patients who underwent surgery for primary or recurrent ACC. DNA-related biomarkers with prognostic role were investigated in frozen and paraffin-embedded samples. Somatic mutations of p53/Rb and Wnt/β-catenin pathways were assessed using next-generation sequencing (n = 26), chromosome alteration profiles were determined using SNP arrays (n = 14) and methylation profiles were determined using four-gene bisulfite pyrosequencing (n = 12).

RESULTS

Somatic mutations for ZNRF3, TP53, CTNN1B and CDKN2A were found in 7, 6, 6 and 4 patients, respectively, with intratumor heterogeneity in 8/26 patients (31%). Chromosome alteration profiles were 'Noisy' (numerous and anarchic alterations) in 8/14 and 'Chromosomal' (extended patterns of loss of heterozygosity) in 5/14 of the study samples. For these profiles, no intratumor heterogeneity was observed. Methylation profiles were hypermethylated in 5/12 and non-hypermethylated in 7/12 of the study samples. Intratumor heterogeneity of methylation profiles was observed in 2/12 patients (17%).

CONCLUSIONS

Intratumor heterogeneity impacts DNA-related molecular markers. While somatic mutation can differ, prognostic DNA methylation and chromosome alteration profile seem rather stable and might be more robust for the prognostic assessment.

Molecular Basis of Primary Aldosteronism and Adrenal Cushing Syndrome

This review reports the main molecular alterations leading to development of benign cortisol- and/or aldosterone-secreting adrenal tumors. Causes of adrenal Cushing syndrome can be divided in 2 groups: multiple bilateral tumors or adenomas secreting cortisol. Bilateral causes are mainly primary pigmented nodular adrenocortical disease, most of the time due to PRKAR1A germline-inactivating mutations, and primary bilateral macronodular adrenal hyperplasia that can be caused in some rare syndromic cases by germline-inactivating mutations of MEN1, APC, and FH and of ARMC5 in isolated forms. PRKACA somatic-activating mutations are the main alterations in unilateral cortisol-producing adenomas. In primary hyperaldosteronism (PA), familial forms were identified in 1% to 5% of cases: familial hyperaldosteronism type I (FH-I) due to a chimeric CYP11B1/CYP11B2 hybrid gene, FH-II due to CLCN-2 germline mutations, FH-III due to KCNJ5 germline mutations, FH-IV due to CACNA1H germline mutations and PA, and seizures and neurological abnormalities syndrome due to CACNA1D germline mutations. Several somatic mutations have been found in aldosterone-producing adenomas in KCNJ5, ATP1A1, ATP2B3, CACNA1D, and CTNNB1 genes.

In addition to these genetic alterations, genome-wide approaches identified several new alterations in transcriptome, methylome, and miRnome studies, highlighting new pathways involved in steroid dysregulation.

Wnt/β-catenin activation cooperates with loss of p53 to cause adrenocortical carcinoma in mice

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with limited therapeutic options. The lack of mouse models that recapitulate the genetics of ACC has hampered progress in the field. We analyzed The Cancer Genome Atlas (TCGA) dataset for ACC and found that patients harboring alterations in both p53/Rb and Wnt/β-catenin signaling pathways show a worse prognosis compared with patients that harbored alterations in only one. To model this, we utilized the Cyp11b2(AS)^Cre mouse line to generate mice with adrenocortical-specific Wnt/β-catenin activation, Trp53 deletion, or the combination of both. Mice with targeted Wnt/β-catenin activation or Trp53 deletion showed no changes associated with tumor formation. In contrast, alterations in both pathways led to ACC with pulmonary metastases. Similar to ACCs in humans, these tumors produced increased levels of corticosterone and aldosterone and showed a high proliferation index. Gene expression analysis revealed that mouse tumors exhibited downregulation of Star and Cyp11b1 and upregulation of Ezh2, similar to ACC patients with a poor prognosis. Altogether, these data show that altering both Wnt/β-catenin and p53/Rb signaling is sufficient to drive ACC in mouse. This autochthonous model of ACC represents a new tool to investigate the biology of ACC and to identify new treatment strategies.

Update on in-vivo preclinical research models in adrenocortical carcinoma

PURPOSE OF REVIEW

The aim of this review is to summarize recent advances on development of in vivo preclinical models of adrenocortical carcinoma (ACC).

RECENT FINDINGS

Significant progress has been achieved in the underlying molecular mechanisms of adrenocortical tumorigenesis over the last decade, and recent comprehensive profiling analysis of ACC tumors identified several genetic and molecular drivers of this disease. Therapeutic breakthroughs, however, have been limited because of the lack of preclinical models recapitulating the molecular features and heterogeneity of the tumors. Recent publications on genetically engineered mouse models and development of patient-derived ACC xenografts in both nude mice and humanized mice now provide researchers with novel tools to explore therapeutic targets in the context of heterogeneity and tumor microenvironment in human ACC.

SUMMARY

We review current in-vivo models of ACC and discuss potential therapeutic opportunities that have emerged from these studies.

β-Catenin and FGFR2 regulate postnatal rosette-based adrenocortical morphogenesis

Rosettes are widely used in epithelial morphogenesis during embryonic development and organogenesis. However, their role in postnatal development and adult tissue maintenance remains largely unknown. Here, we show zona glomerulosa cells in the adult adrenal cortex organize into rosettes through adherens junction-mediated constriction, and that rosette formation underlies the maturation of adrenal glomerular structure postnatally. Using genetic mouse models, we show loss of β-catenin results in disrupted adherens junctions, reduced rosette number, and dysmorphic glomeruli, whereas β-catenin stabilization leads to increased adherens junction abundance, more rosettes, and glomerular expansion. Furthermore, we uncover numerous known regulators of epithelial morphogenesis enriched in β-catenin-stabilized adrenals. Among these genes, we show Fgfr2 is required for adrenal rosette formation by regulating adherens junction abundance and aggregation. Together, our data provide an example of rosette-mediated postnatal tissue morphogenesis and a framework for studying the role of rosettes in adult zona glomerulosa tissue maintenance and function.

CTNNB1 Knockdown Inhibits Cell Proliferation and Aldosterone Secretion Through Inhibiting Wnt/β-Catenin Signaling in H295R Cells

Aldosterone-producing adenomas (APA) is one of the causative factors of primary aldosteronism. Previous studies have suggested that there are somatic CTNNB1 mutations in APA, but the specific mechanism of CTNNB1 mutation in APA tumorigenesis and aldosterone secretion remains unclear. In the present study, human adrenocortical carcinoma cell line H295 R was used to establish stable CTNNB1 knockdown cell lines. Cell proliferation and aldosterone secretion of H295 R cells in response to angiotensin Ⅱ (Agn Ⅱ) were analyzed. We found that CTNNB1 knockdown reduced β-catenin expression and inhibited proliferation of H295 R cells. CTNNB1 knockdown inhibited Wnt/β-catenin signaling pathway and downregulated expression of downstream genes including axin 2, lymphoid enhancer binding factor 1 (LEF1), and cyclin D1. In addition, CTNNB1 knockdown decreased responses of H295 R cells to Agn Ⅱ and decreased aldosterone secretion. Our findings suggest that CTNNB1 knockdown can inhibit H295 R cell proliferation and decrease aldosterone secretion in the responses of H295 R cells to Ang II through inhibiting Wnt/β-catenin signaling pathway, indicating that targeting Wnt/β-catenin signaling pathway may be an important approach to decrease aldosterone secretion in the treatment of aldoster-producing adenomas.

Stem Cells, Self-Renewal, and Lineage Commitment in the Endocrine System

The endocrine system coordinates a wide array of body functions mainly through secretion of hormones and their actions on target tissues. Over the last decades, a collective effort between developmental biologists, geneticists, and stem cell biologists has generated a wealth of knowledge related to the contribution of stem/progenitor cells to both organogenesis and self-renewal of endocrine organs. This review provides an up-to-date and comprehensive overview of the role of tissue stem cells in the development and self-renewal of endocrine organs. Pathways governing crucial steps in both development and stemness maintenance, and that are known to be frequently altered in a wide array of endocrine disorders, including cancer, are also described. Crucially, this plethora of information is being channeled into the development of potential new cell-based treatment modalities for endocrine-related illnesses, some of which have made it through clinical trials.