ECE2019 Poster Presentations Adrenal and Neuroendocrine Tumours 1 (60 abstracts)
Role of KCNJ5 mutations in mediating cell growth in aldosterone-producing adenomas
Yuhong Yang 1 , Lucie S Meyer 1 , Diana Jaquin 1 , Holger Schneider 1 , Maria Ploncynski 2 , Felix Beuschlein 3 , Celso E Gomez-Sanchez 2 , Martin Reincke 1 & Tracy Ann Williams 1,
1Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Ludwig-Maximilians-Universität München, Munich, Germany; 2Endocrine Division, G.V. (Sonny) Montgomery VA Medical Center, University of Mississippi Medical Center, Jackson, MS, USA; 3Klinik für Endokrinologie, Diabetologie und Klinische Ernährung, Universitätsspital Zürich, Zürich, Switzerland; 4Division of Internal Medicine and Hypertension, Department of Medical Sciences, University of Turin, Turin, Italy.
Background: Primary aldosteronism is commonly caused by an aldosterone-producing adenoma (APA). Somatic mutations in the KCNJ5 gene (encoding an inwardly rectifying potassium channel) are found in around 40% of APAs, KCNJ5 germline mutations cause familial hyperaldosteronism type III. The role of KCNJ5 mutations in excessive aldosterone production is established but their role in cell growth is unclear.
Objective: To study the effects of KCNJ5 mutations on cell viability and apoptosis under controlled conditions of gene expression and to assess the expression level of KCNJ5 in APAs.
Methods: Human adrenocortical (HAC15) cell lines stably expressing either a KCNJ5 mutant (G151R, L168R, G151E or T158A) or wild type KCNJ5 and a control cell line transfected with empty vector were established using a cumate-inducible PiggyBac vector system. Cell viability and cell death by apoptosis were quantified using specific assays following induction with cumate. A highly specific monoclonal antibody for KCNJ5 was developed and used in immunohistochemistry and immunofluoresence to demonstrate the distribution and expression level of KCNJ5 in normal adrenals, APAs and corresponding adjacent cortex.
Findings: Under the conditions tested, expression of KCNJ5 G151R, L168R and G151E mutants in HAC15 cells induced apoptosis, KCNJ5 T158A had no effect on cell death. After 12 hours, low level expression of mutated KCNJ5 caused a significant increase in cell proliferation compared with control cells. KCNJ5 displayed low level expression in APAs carrying a KCNJ5 mutation but high expression in APAs with wild type KCNJ5 or with somatic mutations in other genes.
Interpretation: Expression of mutated KCNJ5 at a low level induces cell proliferation in adrenocortical cells. In APAs with KCNJ5 mutations, cell growth is sustained when expression of mutated KCNJ5 is low.
Funding Source: This work was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No [694913]) and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) Projektnummer: 314061271-TRR 205.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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