GSTA1 expression is correlated with aldosterone level in KCNJ5-mutated adrenal aldosterone-producing adenoma

Abstract

Context: KCNJ5 mutation is a major cause of aldosterone-producing adenomas (APAs). The development of APA apart from KCNJ5 mutation is less investigated. Objective: To investigate other mechanisms affecting aldosterone secretion apart from KCNJ5. Patients and Methods: Six pairs of KCNJ5-mutated, high and low aldosterone-secreting APAs, five non-KCNJ5-mutated APAs, and four normal adrenal glands were assayed by Affymetrix GeneChip Human Transcriptome Array 2.0. A total of 113APA samples were investigated to explore the expression of glutathione-S-transferase A1 (GSTA1). H295R cells were used to verify the function of GSTA1. Results: GSTA1 was the top gene downregulated in high-aldosterone KCNJ5-mutated APAs. GSTA1 was also down regulated in KCNJ5-mutated APAs compared with wild-type KCNJ5 APAs. Accordingly, mutant KCNJ5 decreased GSTA1 messenger RNA and protein expression levels. GSTA1 overexpression suppressed aldosterone secretion whether in wild-type or mutant KCNJ5 H295R cells. Adding ethacrynic acid or silencing of GSTA1 increased aldosterone secretion by increasing reactive oxygen species (ROS), superoxide, H2O2 levels, and Ca2+ influx. The expression of the transcription factors NR4A1, NR4A2, and CAMK1 and intracellular Ca2+ were significantly upregulated by GSTA1 inhibition. The reduced form of NAD phosphate oxidase inhibitor or H2O2 scavenger or blocking calmodulin or calcium channels could significantly reduce aldosterone secretion in GSTA1-inhibited cells. Conclusions: (1) GSTA1 expression is reversely correlated with aldosterone level in KCNJ5-mutated APAs, (2) GSTA1 regulates aldosterone secretion by ROS and Ca2+ signaling, and (3) KCNJ5 mutation downregulates GSTA1 expression, and overexpression of GSTA1 reverses increased aldosterone in KCNJ5-mutated adrenal cells.