Primary Aldosteronism: Metabolic Reprogramming and the Pathogenesis of Aldosterone-Producing Adenomas

Metabolic phenotypes and fatty acid profiles associated with histopathology of primary aldosteronism

Primary aldosteronism (PA) caused by aldosterone hypersecretion is treated by adrenalectomy or medications. Histopathologic examination of resected adrenals reveals diverse histopathologic features. This study aimed to investigate the potential association of peripheral and adrenal tissue metabolic profiles with the histopathologic features of PA. The retrospective study included 105 surgically treated and 43 medically treated patients with PA. Adrenal specimens were categorized according to the HISTALDO (HISTopathology of primary ALDOsteronism) consensus. Peripheral and adrenal tissue metabolic profiles were assessed, including adiposity, adipokines and fatty acid abundances. The distinct fatty acid, arachidonic acid, was further functionally characterized. Surgically treated patients with classical histopathologic findings (n = 71) displayed lower body mass indexes, a lower prevalence of obesity, smaller waist circumference and visceral adipose tissue areas, and lower leptin concentrations compared with operated patients with the nonclassical histopathology (n = 34). No such differences were identified between the nonclassical histopathology group and medically treated group. Distinct concentrations of 18 out of 35 peripheral venous fatty acids, including arachidonic acid, were identified among the 3 groups. Further, accumulation of arachidonic acid was demonstrated in 4 aldosterone-producing adenomas compared with paired adjacent cortex possibly linked with suppressed peroxisomal beta-oxidation. Stimulation of human adrenocortical cells with arachidonic acid or peroxisomal beta-oxidation inhibitor caused 3.8-fold (P = 0.0050) and 1.7-fold (P = 0.0328) amplification of CYP11B2 expression, respectively, which were ablated by BAPTA-AM or KN93, and induced oxidative stress and apoptosis. Our findings show metabolic heterogeneity related to histopathology and support a role for arachidonic acid in PA pathophysiology.

EGR1 regulates oxidative stress and aldosterone production in adrenal cells and aldosterone-producing adenomas

Aldosterone-producing adenomas (APAs) are a major cause of primary aldosteronism, a common form of endocrine hypertension. Here, we demonstrate that Early Growth Response 1 (EGR1) plays a dual role in adrenal cell biology, regulating both oxidative stress and aldosterone production. Using RNA sequencing of RSL3-treated human adrenal cells and spatial transcriptomics of adrenal glands from patients with primary aldosteronism, we identify EGR1 as a key gene associated with RSL3-related oxidative stress and APAs. We show that EGR1 silencing decreases oxidative stress and increases CYP11B2 gene expression and aldosterone production in adrenal cells, while its overexpression has the opposite effects. Notably, EGR1 expression is downregulated in APAs and aldosterone-producing micronodules compared to the adjacent adrenal cortex, which correlates in part with decreased levels of oxidative stress markers. The adrenal cortex of pigs with secondary hyperaldosteronism shows decreased immunostaining of EGR1 and a marker of oxidative stress, suggesting a potential link between EGR1 expression, oxidative stress levels, and adrenocortical function. These findings reveal a novel mechanism linking EGR1 to oxidative stress regulation and aldosterone production in adrenal cells, with potential implications for the pathogenesis of APAs and other adrenocortical tumors.

Exogenous dihomo-γ-linolenic acid triggers ferroptosis via ACSL4-mediated lipid metabolic reprogramming in acute myeloid leukemia cells

Ferroptosis is a novel type of programmed cell death caused by excessive iron-dependent lipid peroxidation. According to various studies, there may be a link between ferroptosis and lipid metabolism. However, few studies have been reported on the lipid metabolism of ferroptosis in acute myeloid leukemia (AML). Here, we analyzed the relationship between lipid metabolism and ferroptosis in AML cells to explore new clinical treatment strategies. This study found that 12 fatty acids were significantly changed in acute myeloid leukemia cell ferroptosis, including dihomo-γ-linolenic acid (DGLA), arachidonic acid (AA), docosahexaenoic acid (DHA), etc. Exogenous DGLA substantially increases the sensitivity to ferroptosis and induces ferroptosis alone in AML cells. In addition, acyl-CoA synthetase long-chain family member 4 (ACSL4) knockout significantly inhibited DGLA-induced AML cells ferroptosis, and ACSL4 regulates DGLA-associated lipid synthesis to affect the sensitivity of AML cells to ferroptosis. Collectively, our studies indicate that a DGLA-enriched diet significantly restricted the growth of leukemia cells as well as induced ferroptosis in vivo.

Identification and validation of Novel Estrogen Biosynthesis Biomarkers in Sinonasal Inverted Papilloma

Background: Sinonasal inverted papilloma (SNIP) is characterized by a high recurrence rate and potential for malignant transformation. Although metabolic reprogramming plays a role in benign neoplasms, the specific metabolic pathways and biomarkers involved in SNIP pathogenesis remain unclear. Methods: RNA sequencing on paired SNIP and normal tissues identified altered genes with enzyme annotations and metabolic pathways by intersecting our cohort data (GSE270193, N=2) with the GSE193016 (N=4) dataset using Ingenuity Pathway Analysis. Functional and interaction assessments were performed using Metascape and STRING, with further validation via tissue microarray from an independent SNIP cohort (N=30). Results: The estrogen biosynthesis pathway was significantly altered in both datasets. Five key biomarkers, AKR1B10, CYP1B1, CYP2C19, CYP3A5, and HSD17B13, were significantly altered in SNIP tissues. These markers, sharing Gene Ontology terms, showed significant correlations at both the transcript and protein levels. Functional analysis revealed enrichment in epithelial cell proliferation and regulation of EGFR signaling, suggesting a role in SNIP pathogenesis. Validation in an independent cohort confirmed elevated protein levels of these markers, all positively correlated with EGFR in SNIP tissues. Notably, AKR1B10, CYP2C19, and CYP3A5 exhibited specific expression patterns distinguishing SNIP from sinonasal squamous cell carcinoma. Conclusion: Altered estrogen biosynthesis signaling plays a role in SNIP pathogenesis, revealing distinct biomarkers that could serve as novel diagnostic markers and therapeutic targets for SNIP management.

Evolutionary Characteristics in Primary Aldosteronism Patients

BACKGROUND

Primary aldosteronism is predominantly caused by excessive aldosterone production from the adrenal cortex, and the aldosterone-producing structures could take many forms, like adenomas, nodules, micronodules, and so on. Most studies of primary aldosteronism were limited to the hotspot driver genes responsible for autonomous aldosterone production; however, the panoramic genetic architecture and genomic alterations of aldosterone-producing structures and their adjacent hyperplasia glands remain unknown.

METHODS

In this study, whole-exome sequencing and transcriptome sequencing (RNA-seq) analyses were performed using functional nodules and matched hyperplasia tissues, which were microdissected guided by aldosterone synthase immunohistochemistry. Phylogenetic trees were constructed based on the shared and unique mutations, gene mutation spectrums, and clonal characteristics.

RESULTS

The rates of mutations represented higher means of functional nodules than hyperplasia samples, and the little mutational overlap was shown between the 2 groups on phylogenetic trees. The mutations of the aldosterone driver gene (KCNJ5 or CACNA1D) were only observed in functional nodules and indicated almost the largest values of cancer cell fraction. Moreover, the functional nodules also harbored some potential variants related to cell proliferation, which were not detected in hyperplasia tissues. Transcriptome analysis suggested that only 25.5% upregulated and 23.3% downregulated genes overlapped between functional nodules and hyperplasia tissues.

CONCLUSIONS

This study demonstrated a genetic and transcriptome landscape of aldosterone-producing structures and adjacent hyperplasia glands in primary aldosteronism. The results indicated independent clonal origins on functional nodules and hyperplasia tissues, and little mutual evolutionary relationship was found on their phylogenetic trees.

Ferroptosis and its Potential Determinant Role in Myocardial Susceptibility to Ischemia/Reperfusion Injury in Diabetes

Myocardial ischemia/reperfusion injury (MIRI) is a major cause of cardiac death particularly in patients with diabetes. When the coronary artery is partially or completely blocked, restoration of blood perfusion can normally be achieved within a certain time due to the development of advanced techniques such as percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) surgery. However, cardiac tissue injury may aggravate progressively even after the ischemic myocardium is restored to normal perfusion. MIRI is often associated with various forms of cell death, including apoptosis, autophagy, programmed necrosis, pyroptosis, and ferroptosis, among others. Ferroptosis is known as iron-dependent cell death that is distinct from other programmed modes of cell death. Ferroptosis is under constitutive control by glutathione peroxidase 4 (GPX4), and the reduction of GPX4 may result in ferroptosis even if iron homeostasis is physiologically maintained. The essences of ferroptosis are substantial iron accumulation and lipid peroxidation that trigger cell death. Under impaired antioxidant system, cellular reactive oxygen species (ROS) accumulation leads to lipid peroxidation which consequently results in ferroptosis. Ferroptosis shares a few common features with several types of cell death and interplays with various forms of cell death such as autophagy and apoptosis in the development of cardiovascular diseases. More and more recent studies have demonstrated that ferroptosis plays an important role in MIRI. However, few studies have addressed the relative importance of ferroptosis in MIRI relative to other forms of cell deaths. In this review, we summarized the basic aspects and advances regarding the molecular pathogenesis of ferroptosis, evaluated its role in MIRI, and propose that the levels of ferroptosis may function as a major determinant of myocardial susceptibility to ischemia/reperfusion injury (IRI) in general and of the enhanced vulnerability to MIRI specifically in diabetes.

Mammalian Target of Rapamycin Inhibition Decreases Angiotensin II-Induced Steroidogenesis in HAC15 Human Adrenocortical Carcinoma Cells

BACKGROUND

Mammalian target of rapamycin (mTOR) inhibitors suppress adrenal cortical carcinoma cell proliferation and cortisol production; the relationship between mTOR and aldosterone production has not been examined.

METHODS

HAC15 cells were incubated with an mTOR activator and several inhibitors including AZD8055 (AZD) in the presence and absence of angiotensin II (AngII). The expression of rapamycin-sensitive adapter protein of mTOR (Raptor) and rapamycin-insensitive companion of mTOR (Rictor), adaptor proteins of mTOR complex 1 and 2, respectively, were studied in the HAC15 cells and deleted by CRISPR/gRNA.

RESULTS

The mTOR inhibitors decreased aldosterone induced by AngII. Inhibition of mTOR by AZD significantly suppressed AngII-induced aldosterone and cortisol formation in a dose-dependent manner, whereas the mTOR activator MHY had no effect. AZD did not alter forskolin-induced aldosterone production showing that it is specific to the AngII signaling pathway. AngII-mediated ERK and mTOR activation were suppressed by AZD, along with a concomitant dose-dependent reduction of AngII-induced steroidogenic enzymes including steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase-type 2, CYP17A1, and aldosterone synthase protein. Furthermore, mTOR components ribosomal protein S6 kinase (P70S6K) and protein kinase B phosphorylation levels were decreased by AZD. As mTOR exerts its main effects by forming complexes with adaptor proteins Raptor and Rictor, the roles of these individual complexes were studied. We found an increase in the phosphorylation of Raptor and Rictor by AngII and that their CRISPR/gRNA-mediated knockdown significantly attenuated AngII-induced aldosterone and cortisol production.

CONCLUSION

mTOR signaling has a critical role in transducing the AngII signal initiating aldosterone and cortisol synthesis in HAC15 cells and that inhibition of mTOR could be a therapeutic option for conditions associated with excessive renin-angiotensin system-mediated steroid synthesis.

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.

Hypomethylation associated vitamin D receptor expression in ATP1A1 mutant aldosterone-producing adenoma

DNA methylation alteration is tissue-specific and play a pivotal role in regulating gene transcription during cell proliferation and survival. We aimed to detect genes regulated by DNA methylation, and then investigated whether the gene influenced cell proliferation or survival in adrenal cells. DNA methylation and qPCR analyses were performed in nonfunctioning adrenocortical adenoma (NFA, n = 12) and aldosterone-producing adenoma (APA, n = 35) samples. The VDR gene promoter was markedly hypomethylated in APA with ATP1A1 mutation, and the promoter methylation levels showed a significant inverse association with the transcripts in APA. ATP1A1 mutation led to VDR transcription in HAC15 cells, and VDR suppression abrogated ATP1A1 mutation-mediated cell proliferation in HAC15 cells. We demonstrated that APA with ATP1A1 mutation showed entire hypomethylation in the VDR promoter and abundant VDR mRNA and protein expression. VDR suppression abrogated ATP1A1 mutation-mediated cell proliferation in HAC15 cells. Abundant VDR expression would be essential for ATP1A1 mutation-mediated cell proliferation.

Transcriptomics, Epigenetics, and Metabolomics of Primary Aldosteronism

INTRODUCTION

Primary aldosteronism (PA) is the most common cause of endocrine hypertension, mainly caused by aldosterone-producing adenomas or hyperplasia; understanding its pathophysiological background is important in order to provide ameliorative treatment strategies. Over the past several years, significant progress has been documented in this field, in particular in the clarification of the genetic and molecular mechanisms responsible for the pathogenesis of aldosterone-producing adenomas (APAs).

METHODS

Systematic searches of the PubMed and Cochrane databases were performed for all human studies applying transcriptomic, epigenetic or metabolomic analyses to PA subjects. Studies involving serial analysis of gene expression and microarray, epigenetic studies with methylome analyses and micro-RNA expression profiles, and metabolomic studies focused on improving understanding of the regulation of autonomous aldosterone production in PA were all included.

RESULTS

In this review we summarize the main findings in this area and analyze the interplay between primary aldosteronism and several signaling pathways with differential regulation of the RNA and protein expression of several factors involved in, among others, steroidogenesis, calcium signaling, and nuclear, membrane and G-coupled protein receptors. Distinct transcriptomic and metabolomic patterns are also presented herein, depending on the mutational status of APAs. In particular, two partially opposite transcriptional and steroidogenic profiles appear to distinguish APAs carrying a KCNJ5 mutation from all other APAs, which carry different mutations.

CONCLUSIONS

These findings can substantially contribute to the development of personalized treatment in patients with PA.

ATP1A1 Mutant in Aldosterone-Producing Adenoma Leads to Cell Proliferation

The molecular mechanisms by which ATP1A1 mutation-mediated cell proliferation or tumorigenesis in aldosterone-producing adenomas (APAs) have not been elucidated. First, we investigated whether the APA-associated ATP1A1 L104R mutation stimulated cell proliferation. Second, we aimed to clarify the molecular mechanisms by which the ATP1A1 mutation-mediated cell proliferated. We performed transcriptome analysis in APAs with ATP1A1 mutation. ATP1A1 L104R mutation were modulated in human adrenocortical carcinoma (HAC15) cells (ATP1A1-mutant cells), and we evaluated cell proliferation and molecular signaling events. Transcriptome and immunohistochemical analysis showed that Na/K-ATPase (NKA) expressions in ATP1A1 mutated APA were more abundant than those in non-functioning adrenocortical adenoma or KCNJ5 mutated APAs. The significant increase of number of cells, amount of DNA and S-phase population were shown in ATP1A1-mutant cells. Fluo-4 in ATP1A1-mutant cells were significantly increased. Low concentration of ouabain stimulated cell proliferation in ATP1A1-mutant cells. ATP1A1-mutant cells induced Src phosphorylation, and low concentration of ouabain supplementation showed further Src phosphorylation. We demonstrated that NKAs were highly expressed in ATP1A1 mutant APA, and the mutant stimulated cell proliferation and Src phosphorylation in ATP1A1-mutant cells. NKA stimulations would be a risk factor for the progression and development to an ATP1A1 mutant APA.