Context: The aberrant expression or alternation of miRNA in the pathogenesis of aldosterone-producing adenomas (APAs) is still largely unknown.
Objective: We investigated the role of miRNA-203 (screened from miRNA microarrays) and elucidated its effects on the Wnt/β-catenin pathway regarding aldosterone production and cell proliferation in APAs.
Methods: miR-203 expression was upregulated or downregulated by transfecting miR-203 mimics or inhibitors into primary APA cells, the human adrenocortical cell line HAC15, and C57BL/6 mice. In vitro and biochemical data were correlated with the respective clinical parameters of APAs to evaluate their clinical importance.
Results: The expression of miR-203 in human APA samples was significantly lower than that of peritumor adrenal samples. Tumoral miR-203 abundance correlated negatively with both plasma aldosterone level and tumor size in patients with APAs. miR-203 inhibitors increased aldosterone production and cell proliferation in HAC15 cells, and restoration of expression via miR-203 mimics showed decreased cell proliferation and aldosterone hypersecretion in APA cell cultures. In vivo selective inhibition of miR-203 via intra-adrenal injection of miR-203 inhibitors in mice led to a substantial increase in systolic blood pressure and plasma aldosterone levels. Additionally, the dual-luciferase reporter assay demonstrated that WNT5A is a direct target of miR-203. Furthermore, plasma Wnt5a levels in adrenal vein sampling were helpful in differentiating tumor localization, and preoperative plasma Wnt5a levels predicted the cure of hypertension after adrenalectomy.
Conclusion: We have demonstrated that attenuated miR-203 expression in APAs increases aldosterone production and the tumorigenesis of adrenal cells by activating the Wnt5a/β-catenin pathway.