Macrolides selectively inhibit mutant KCNJ5 potassium channels that cause aldosterone-producing adenoma
Ute I. Scholl, Laura Abriola, Chengbiao Zhang, Esther N. Reimer, Mark Plummer, Barbara I. Kazmierczak, Junhui Zhang, Denton Hoyer, Jane S. Merkel, Wenhui Wang, Richard P. Lifton
Ute I. Scholl, Laura Abriola, Chengbiao Zhang, Esther N. Reimer, Mark Plummer, Barbara I. Kazmierczak, Junhui Zhang, Denton Hoyer, Jane S. Merkel, Wenhui Wang, Richard P. Lifton
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Research Article Endocrinology Nephrology

Macrolides selectively inhibit mutant KCNJ5 potassium channels that cause aldosterone-producing adenoma

Abstract

Aldosterone-producing adenomas (APAs) are benign tumors of the adrenal gland that constitutively produce the salt-retaining steroid hormone aldosterone and cause millions of cases of severe hypertension worldwide. Either of 2 somatic mutations in the potassium channel KCNJ5 (G151R and L168R, hereafter referred to as KCNJ5MUT) in adrenocortical cells account for half of APAs worldwide. These mutations alter channel selectivity to allow abnormal Na+ conductance, resulting in membrane depolarization, calcium influx, aldosterone production, and cell proliferation. Because APA diagnosis requires a difficult invasive procedure, patients often remain undiagnosed and inadequately treated. Inhibitors of KCNJ5MUT could allow noninvasive diagnosis and therapy of APAs carrying KCNJ5 mutations. Here, we developed a high-throughput screen for rescue of KCNJ5MUT-induced lethality and identified a series of macrolide antibiotics, including roxithromycin, that potently inhibit KCNJ5MUT, but not KCNJ5WT. Electrophysiology demonstrated direct KCNJ5MUT inhibition. In human aldosterone-producing adrenocortical cancer cell lines, roxithromycin inhibited KCNJ5MUT-induced induction of CYP11B2 (encoding aldosterone synthase) expression and aldosterone production. Further exploration of macrolides showed that KCNJ5MUT was similarly selectively inhibited by idremcinal, a macrolide motilin receptor agonist, and by synthesized macrolide derivatives lacking antibiotic or motilide activity. Macrolide-derived selective KCNJ5MUT inhibitors thus have the potential to advance the diagnosis and treatment of APAs harboring KCNJ5MUT.

Authors

Ute I. Scholl, Laura Abriola, Chengbiao Zhang, Esther N. Reimer, Mark Plummer, Barbara I. Kazmierczak, Junhui Zhang, Denton Hoyer, Jane S. Merkel, Wenhui Wang, Richard P. Lifton

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Figure 3

Dose-response curves of lead macrolide compounds on WT and mutant KCNJ5.

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Dose-response curves of lead macrolide compounds on WT and mutant KCNJ5....
Dose-response curves of roxithromycin, clarithromycin, and idremcinal on activity of WT and mutant (G151R and L168R) KCNJ5 are shown. For mutant KCNJ5, percentage of inhibition denotes increase in ATP, measured by luminescence, in the presence of drug. For WT KCNJ5, percentage of inhibition denotes change in membrane potential in the presence of drug (see Methods). Compounds were tested in technical triplicates at 20, 10, 5, 2.5, 1.25, 0.625, 0.3125, 0.1563, 0.0781, and 0.0391 μM concentrations. Data were fit with a 4-parameter nonlinear regression of log-dose versus response. While inhibition of mutant channels showed a strong dose-response relationship with all 3 compounds, there was no significant inhibition of WT channels. See Table 1 for inhibition data.