Compound-induced NR5A1 circular RNA and aberrant multiple exon-skipping attenuate aberrant steroidogenesis

Despite the intensive search for an effective drug to ameliorate excess steroid production, there are few pharmacological options, especially for diseases as steroid-producing adrenocortical cancers. While splice-modifying-compounds have pleiotropic effects including anticancer properties, none have been tested on abnormal steroidogenesis. Using H295R adrenocortical carcinoma cells, CX-4945 induced multiple exon skipping of the NR5A1 gene, the master regulator of steroidogenesis. The resulting exon-skipped NR5A1 proteins were non-functional when added-back to NR5A1 knocked down H295R cells. This eventually suppressed steroidogenesis and induced dysfunctional autophagy with progression to ER-stress-related apoptosis. Intriguingly, a circular RNA of NR5A1 exons (circNR5A1 ex2-4 RNA) not originating from the skipped exons, was induced. Transient expression of this circNR5A1 ex2-4 RNA induced the same multiple exon-skipped isoforms of the NR5A1 gene. This potential pharmacological control of NR5A1 aberrant multiple exon-skipping and interplay with its circNR5A1 RNA gives us a novel target for treating abnormal steroidogenesis in adrenocortical carcinomas. CX-4945-induced gene expression in H295R adrenocortical cancer cells was compared with solvent (DMSO) treated H295R cells.