Compound-induced NR5A1 exon-skipping and circular-RNA expression show impaired steroidogenesis in adrenocortical cancer cells

Despite the intensive search for an effective drug to treat steroid-producing adrenocortical carcinomas, there are few therapeutic options. We sought whether splicing modifying compounds are effective on this devastating disease. Here, we show that a chemical compound in clinical trial, CX-4945, suppressed the expression of NR5A1 through aberrant multiple exon skipping leading to suppressed steroidogenesis and induced dysfunctional autophagy and progression to ER-stress-related apoptosis. A circular RNA of NR5A1 exons with an IRE1α-cleavage site on the ligated ends (circAd4BP HAC1-type ex1-6 RNA) is expressed in normal adrenal cortex but not in H295R adrenocortical cancer cells, and CX-4945 induced a different circular RNA of NR5A1 exons (circAd4BP ex2-4 RNA). This potential pharmacological control of abnormal steroidogenesis through NR5A1 aberrant splicing and interplay with its circAd4BP makes CX-4945 a strong candidate novel drug for the treatment of adrenocortical carcinomas. CX-4945-induced gene expression in H295R adrenocortical cancer cells was compared with solvent (DMSO) treated H295R cells.