miR-486-5p and miR-144-3p as candidate regulators of cortisol biosynthesis: functional and transcriptomic evidence in adrenocortical cells

BACKGROUND: MicroRNA (miRNA) have been identified to regulate gene expression in adrenal disorders. OBJECTIVE: To investigate the effects of specific miRNAs on cortisol biosynthesis. METHODS: Seven candidate miRNAs were transfected as mimics into steroidogenically active adrenocortical cell lines (NCI-H295R, HAC15, CU-ACC1). Steroids were measured by LC-MS/MS and ELISA. QPCR was performed in all cell lines with additionally microarray analysis in HAC15 cells. Adrenal RNA-Sequencing data from patients with Cushing's syndrome (CS, n = 10) and normal controls (n = 8) were analysed to compare gene expression genes (DEGs) and enrichments. miRNA inhibitors were further used for validation. RESULTS: MiR-486-5p and miR-144-3p mimics reduced cortisol levels by ∼60-70% in NCI-H295R and HAC15 cells, and LC-MS/MS confirmed reduced steroidogenic metabolites. Both miR-486-5p and miR-144-3p mimics significantly inhibited CYP17A1 and CYP11B2 mRNA levels in NCI-H295R and HAC15 cells. Microarray analysis revealed the DEGs induced by miR-486-5p or miR-144-3p both predominantly enriched in "Metabolic Pathways", consistent with enrichment in the CS adrenal dataset. Common metabolic genes (co-DEGs) between patient samples and miRNA mimic-treated cells exhibited complementary expression patterns. Co-transfection of the corresponding inhibitors attenuated cortisol suppression and metabolic gene changes. Protein-protein interaction analysis further clustered the miR-486-5p and miR-144-3p associated co-DEGs into lipid metabolism related biological process. CONCLUSION: MiR-486-5p and miR-144-3p suppress cortisol production in the human adrenocortical cell models of NCI-H295R and its derived HAC15 subclone, and are associated with lipid metabolism related networks, providing new insights into the molecular regulation of cortisol biosynthesis.