YAP1 inhibits circRNA-000425 expression and thus promotes oncogenic activities of miR-17 and miR-106.

YAP1, a vital effector of Hippo pathway, promotes cancer development via transcriptionally regulating a batch of target genes involved in various signaling pathways, including proliferation, apoptosis, and cell drug sensitivity. Recently, circular RNAs (circRNAs) have been shown to control gene expression post-transcriptionally and become a new layer of gene regulation. However, whether circRNAs play roles in YAP1-induced tumorigenesis is still largely elusive. Here, we identify circRNA-000425 as a new inhibitory target of YAP1, and also find that it binds to miR-17/miR-106b, and thus suppresses cancer cell growth induced by these miRNAs. circRNA-000425 is revealed as a YAP1 target through circRNA microarray analysis of RNAs extracted from cells treated with or without YAP1 siRNAs, and further confirmed by RT-q-PCR and ChIP assays. Interestingly, bioinformatics analysis, luciferase assay, and RT-q-PCR results showed that circRNA-000425 binds to miR-17 and miR-106b, but not let-7a, and rescues the inhibitory effect of miR-17/miR-106 on the expressions of both p21 and BIM. In addition, colony formation and MTT assay showed that circRNA-000425 inhibits cancer cell growth induced by miR-17. These findings reveal a mechanism by which YAP1 promotes oncogenic activities of miR-17 and miR-106b through transcriptionally inhibiting circRNA-000425 expression.