Immunohistochemical, genetic and clinical characterization of sporadic aldosterone-producing adenomas

Abstract

Adrenal glands removed for unilateral primary aldosteronism (PA) display marked histological heterogeneity. Recently reported somatic mutations in KCNJ5, ATP1A1, ATP2B3 and CACNA1D can partially account for these differences. In this study we aimed at combining phenotypic and genotypic characteristics, integrating genetic and immunohistochemistry correlates in sporadic PA. Seventy-one adrenal glands have been included in the study and analyzed for mutations in KCNJ5, ATP1A1, ATP2B3 and CACNA1D. Histological examination and immunohistochemical staining for CYP11B1 (11β-hydroxylase) and CYP11B2 (aldosterone synthase) were performed on aldosterone-producing adenomas (APAs) and adjacent adrenal cortex. In our cohort, the final histopathological diagnosis was multinodular hyperplasia in 22.5% of the patients and single nodule in 77.5%. Forty-five percent of the removed adrenals displayed extra-APA CYP11B2-positive cell nests (B2-CN). Among adrenal vein sampling parameters the suppression of contralateral adrenal was more frequent and the lateralization index was higher in the subgroup of patients without extra-APA B2-CN compared to the subgroup with extra-APA B2-CN. KCNJ5-mutated APAs were composed mainly of zona fasciculata-like cells with high expression of CYP11B1, while ATP1A1, ATP2B3 and CACNA1D-mutated APAs presented more frequently a zona-glomerulosa-like phenotype with high expression of CYP11B2. We observed a significant inverse correlation between CYP11B2 expression and the size of the nodules and, if CYP11B2 expression was corrected for tumor volume, a significant correlation with plasma aldosterone and aldosterone to renin ratio. Our findings indicate that combination of genotyping and immunohistochemistry improves the final histopathological diagnosis between single nodule and multinodular hyperplasia of the assessed adrenals.

Aldosterone-stimulating somatic gene mutations are common in normal adrenal glands

“…Such approaches may illuminate drivers in ∼65% of APCCs that did not harbor candidate drivers by our panel-based approach. Of interest, no well-supported somatic KCNJ5 mutations were observed in our APCCs subjected to NGS, although mutations in KCNJ5 occur in at least 30% of APAs (7,8,17,21). Given that APCCs in our cohort harbored somatic mutations in CACNA1D (26%) and ATP1A1 (9%), at residues previously reported in APA, APCCs may represent a precursor population of cells that lead to APA with these mutations through unknown mechanisms.…”

“…There have been several reports that find cellular histologic correlations with aldosterone-stimulating mutations (9,13,17,27). Therefore, we examined the cell histology of APCC samples that were captured for sequence analysis (Fig.…”

“…These clusters or nests of cells, therefore, differ from the typical zonation seen in human and rodent adrenals [zona glomerulosa (ZG), ZF, and zona reticularis (ZR)]. Interestingly, APCCs are also frequently found in adrenal tissue adjacent to APA, despite the low circulating renin/angiotensin levels found in patients with APA, suggesting that APCC production of aldosterone is renin-independent (autonomous) (15)(16)(17). Although these studies suggest a role for APCCs in autonomous aldosterone production and potentially, PA, previous reports have been limited to immunohistochemical analysis.…”

Targeting CXCR4 (CXC Chemokine Receptor Type 4) for Molecular Imaging of Aldosterone-Producing Adenoma

“…Patients with unilateral APA had been diagnosed according to the 2008 Endocrine Society Practice Guidelines. 32 Collection of patient data and samples was approved by the ethical committees of the respective institutions (Wuerzburg 88/11, Essen 01-187-1787-Z, Charité Berlin EA1/169/08, 33 Munich 379/10, Turin CEI/349). All patients had provided written informed consent.…”

The Plasma Membrane Calcium ATPasesand Their Role as Major New Players in Human Disease

“…With the exception of one Taiwanese patient who exhibited a Tyr410Asp substitution (404), all mutations identified thus far involve the deletion of one or more amino acids between Thr-423 and Leu-433 lying in the M4 region of the plasma membrane, believed to be important in Ca 2ϩ binding during its transport to the extracellular space. Clinically APAs containing ATP2B3 mutations are associated with higher levels of aldosterone secretion when compared with wild-type APAs (27,186,397), most likely as a result of an observed increase in aldosterone synthase CYP11B2 expression (250,254,396). Recently these associations have been confirmed through the transfection of ATP2B3 carrying the common Leu425_Val426 deletion into adrenocortical NCI-H295R cells, resulting in impaired Ca 2ϩ clearance accompanied by elevated basal Ca 2ϩ , CYP11B2 expression, and aldosterone secretion (370).…”