Abstract
Background: Primary aldosteronism (PA) is the most common cause of secondary hypertension, accounting for 5-8% of all hypertension. PA is most commonly attributed to an aldosterone-producing adenoma (APA) or to bilateral hyperaldosteronism (BHA). Mutations in the inward-rectifying K(+) channel (mKCNJ5), which increase autonomous aldosterone production, are most frequently detected in APAs. APAs with mKCNJ5 display aberrant expression of aldosterone synthase (CYP11B2) and 17α-hydroxylase (CYP17A1), which are involved in aldosterone and cortisol synthesis, respectively. Co-expression of these enzymes results in the production of a set of “hybrid” steroids, which have been proposed as serum biomarkers. The relative production of hybrid steroids in adrenal tumors vs. adjacent normal adrenal (NA) tissue has not been investigated. Objectives: To determine the utility of OCT-embedded adrenal tumor tissue for steroid profiling. To use immunohistochemistry (IHC)-guided OCT tumor capture for intratumoral hybrid steroid profiling in mKCNJ5 APA and NA tissue. Methods: OCT-embedded adrenal tissue from 9 patients (8 women, Age 45.9 ± 3.3 years) with APAs harboring known KCNJ5 mutations were used for the study. Where available OCT-embedded normal adrenal (NA) tissue adjacent to APAs were used as controls (n=4). IHC was performed for CYP11B2 and CYP17A1 on OCT tissue allowing guided APA capture from serial sections. Steroids were extracted from APA and adjacent NA tissue, and quantified by liquid chromatography/tandem mass spectrometry. Steroids measured were normalized to the protein content of the extracted tissue. Results: Compared to NA, APA tissue demonstrated 23-, 5.6- and 6.4-fold higher levels of aldosterone, 11-deoxycorticosterone, and 18-hydroxycorticosterone, respectively (P<0.05). In addition, the “hybrid” steroid products, 18-oxocortisol and 18-hydroxycortisol, were significantly elevated in APA vs. NA (P<0.01). Conversely, the adrenal androgens dehydroepiandrosterone and 11-hydroxyandrostenedione were lower in APA as compared with NA (P<0.05). All mKCNJ5 APAs were also found to co-express CYP11B2 and CYP17A1. Conclusion: IHC-guided mKCNJ5 APA capture and steroid extraction identified a distinct intratumoral hybrid steroid signature that associated with co-expression of CYP11B2 and CYP17A1.These findings also demonstrate that OCT-embedded tissue can be used to accurately define intra-tissue steroid profiles, which will have application for steroid-producing and steroid-responsive tumors.