Primary aldosteronism: Small molecule antagonists of mutant KCNJ5 potassium channels

Sanas Mir-Bashiri; Martina Tetti; Dennis Froebel; Dunja Reiss; Nicole Bechmann; Mirko Peitzsch; Graeme Eisenhofer; Martin Reincke; Tracy Ann Williams

doi:10.1530/endoabs.99.P419

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Endocrine Abstracts (2024) 99 P419 | DOI: 10.1530/endoabs.99.P419

ECE2024 Poster Presentations Adrenal and Cardiovascular Endocrinology (95 abstracts)

Primary aldosteronism: Small molecule antagonists of mutant KCNJ5 potassium channels

Sanas Mir-Bashiri ¹ , Martina Tetti ² , Dennis Froebel ³ , Dunja Reiss ¹ , Nicole Bechmann ³ , Mirko Peitzsch ³ , Graeme Eisenhofer ³ , Martin Reincke ¹ & Tracy Ann Williams ¹

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¹Klinikum der Universität München, Endocrine Research Unit, München, Germany; ²University of Turin, Torino, Italy; ³University Hospital Carl Gustav Carus Dresden, Dresden, Germany

Background: Primary aldosteronism (PA) is the most frequent cause of endocrine hypertension associated with excess aldosterone production from one or both adrenal glands. Somatic or germline mutations in the KCNJ5 potassium channel cause an imbalance in intracellular ion homeostasis. This ultimately drives aldosterone overproduction in some sporadic forms of PA and a familial form of the disease (familial hyperaldosteronism type 3). Our objective was to identify small molecule compounds that could be used in managing patients with PA driven by a KCNJ5 mutation.

Methods: A virtual screening of > 6 million low molecular weight compounds was used to identify candidate molecules potentially interacting with the KCNJ5 channel. Functional testing through WST-1 assays and flow cytometry was performed to quantify the inhibition of cell death mediated by high-level expression of KCNJ5 mutants in human adrenocortical cell lines (HAC15).

Results: In silico screening of the small molecule library identified 108 candidate molecules. One of these, referred to as C-81, was a spirocyclic molecule featuring an indene and pyrroloquinoline system that inhibited HAC15 cell death induced by mutant KCNJ5 overexpression by 34.95% (measured via flow cytometry, P<0.001). The effect of C-81 on different KCNJ5 mutations close to the channel pore was quantified by qPCR showing a 75% decrease in CYP11B2 (aldosterone synthase) gene expression for KCNJ5 L168R mutations (P<0.001) and 91% decrease for T158A mutations (P<0.001). In contrast, C-81 only had a non-significant effect on CYP11B2 gene expression levels in native HAC15 cells (P=0.25). Using a steady state system for in vitroevaluation of steroidogenic pathway dynamics, C-81 treatment resulted in up to a 50% reduction of aldosterone production.

Conclusion: C-81 is a candidate small molecule antagonist of mutated KCNJ5 which could have potential therapeutic use to decrease pathological aldosterone secretion in some sporadic and familial forms of PA.