Analysis of Unilateral Adrenal Hyperplasia with Primary Aldosteronism from the Aspect of Messenger Ribonucleic Acid Expression for Steroidogenic Enzymes: A Comparative Study with Adrenal Cortices Adhering to Aldosterone-Producing Adenoma

Abstract

Unilateral adrenal hyperplasia with primary aldosteronism is very rare and shows similar endocrine features to aldosterone-producing adenoma and bilateral adrenal hyperplasia. In this study, the mRNA expression of steroidogenic enzymes in unilateral adrenal hyperplasia was examined by in situ hybridization. We found subcapsular micronodules composed of spironolactone body-containing cells, which showed intense expression for 3beta-hydroxysteroid dehydrogenase, 11beta-hydroxylase, 18-hydroxylase, and 21-hydroxylase but not 17alpha-hydroxylase, indicating aldosterone production. This expression pattern was the same as that in unilateral multiple adrenocortical micronodules, reported recently. Additionally, it was noted that a nodule with active aldosterone production was closely adjacent to one showing intense 17alpha-hydroxylase expression. In the adrenal cortices adhering to aldosterone-producing adenoma, the majority of hyperplastic zona glomerulosa and hyperplastic nodules demonstrated a decreased steroidogenic activity. However, minute nodules indicative of active aldosterone production were found at high frequency. These results suggest that the subcapsular micronodules observed might be the root of aldosterone-producing adenoma. Furthermore, we emphasize the need for long-term follow-up after unilateral adrenalectomy or enucleation of the adenoma because of the possibility that buds with autonomous aldosterone production may still be present in the contralateral or remaining adrenal tissue.

Analysis of mRNA expression for steroidogenic enzymes in the remaining adrenal cortices attached to adrenocortical adenomas.

“…Antisensestrand cRNAs were synthesized using Digoxigenin (DIG)-UTP (Roche Diagnostics) with T 3 or T 7 RNA polymerase (Takara, Otsu, Japan). The probe CYP11B used in this study could not discriminate between 11b-hydroxylase and aldosterone synthase, since the nucleotide sequences of CYP11B1 and CYP11B2 encoding 11b-hydroxylase and aldosterone synthase are 95% identical (11,19).…”

“…In situ hybridization cDNA fragments of steroidogenic acute regulatory protein (StAR), CYP11A1, HSD3B2, CYP11B, CYP17A1, CYP21A2, sulfotransferase (SULT2A1), and melanocortin 2 receptor (MC2R), which were encoding human StAR protein, cholesterol side-chain cleavage enzyme, 3b-hydroxysteroid dehydrogenase, 11b-hydroxylase and/or aldosterone synthase, 17a-hydroxylase, 21-hydroxylase, DHEA sulfotransferase, and receptor for ACTH, respectively, were obtained by reverse transcriptase-PCR and subcloned into pT-NOT vector (11,18). Antisensestrand cRNAs were synthesized using Digoxigenin (DIG)-UTP (Roche Diagnostics) with T 3 or T 7 RNA polymerase (Takara, Otsu, Japan).…”

“…In situ hybridization was performed as described previously (11,18). Briefly, 3 mm thick sections were hybridized with DIG-labeled cRNA probes at 42 8C for 16 h and finally washed in 0.2!SCC at 50 8C for 20 min.…”

“…However, histochemical and electron microscopic studies have shown that some ischemia-related cortical nodules had steroidogenic activity (9,10). We have recently demonstrated that the cortices attached to APA contained not only microscopic subcapsular micronodules suggesting active aldosterone production, as observed in bilateral adrenal hyperplasia (BAH) and unilateral adrenal hyperplasia (UAH), but also cortical nodules suggesting the capability for producing cortisol (11). Hence, the possibility is suggested that buds with autonomous production of aldosterone or cortisol may exist in the cortices attached to APA.…”

G-protein-coupled receptors in aldosterone-producing adenomas: a potential cause of hyperaldosteronism

“…It is currently not clear if the adenomas with low CYP11B2 expression are the source of aldosterone in these patients. Other studies suggest that subcapsular micronodules have varying expression of steroidogenic enzymes -some with aldosterone synthase and some without (Shigematsu et al 2006). Future studies are required to determine whether some tumor-bearing adrenals from PA patients also have small CYP11B2-positive micronodules as the source of aldosterone production.…”