Upregulation of microRNA-96 and its oncogenic functions by targeting CDKN1A in bladder cancer

Genome-wide miRNA expression profile has identified microRNA (miR)-96 as one of upregulated miRNAs in clinical bladder cancer (BC) tissues compared to normal bladder tissues. The aim of this study was to confirm the expression pattern of miR-96 in BC tissues and to investigate its involvement in carcinogenesis.

Quantitative real-time PCR was performed to detect the expression levels of miR-96 in 60 BC and 40 normal control tissues. Bioinformatics prediction combined with luciferase reporter assay were used to verify whether the cyclin-dependent kinase inhibitor CDKN1A was a potential target gene of miR-96. Cell counting kit-8 and apoptosis assays were further performed to evaluate the effects of miR-96-CDKN1A axis on cell proliferation and apoptosis of BC cell lines.

We validated that miR-96 was significantly increased in both human BC tissues and cell lines. According to the data of miRTarBase, CDKN1A might be a candidate target gene of miR-96. In addition, luciferase reporter and Western blot assays respectively demonstrated that miR-96 could bind to the putative seed region in CDKN1A mRNA 3'UTR, and significantly reduce the expression level of CDKN1A protein. Moreover, we found that the inhibition of miR-96 expression remarkably decreased cell proliferation and promoted cell apoptosis of BC cell lines, which was consistent with the findings observed following the introduction of CDKN1A cDNA without 3'UTR restored miR-96.

Our data reveal that miR-96 may function as an onco-miRNA in BC. Upregulation of miR-96 may contribute to aggressive malignancy partly through suppressing CDKN1A protein expression in BC cells.