Livin expression may be regulated by miR-198 in human prostate cancer cell lines

Livin has been recently described as an inhibitor of apoptosis, which is established to be associated with a variety of cancers. Metastatic prostate cancer cell line DU145 expresses high level of Livin mRNA yet low level of its protein. Thus, we hypothesised that Livin was regulated by some miRNAs in prostate cancer cells. Livin mRNA and protein expression were investigated by reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot, respectively. Hairpin RT-PCR was performed to analyse suspected miRNAs. Livin 3'-untranslated region (3'-UTR) wild type and mutant dual-luciferase reporter vectors were constructed. The miRNAs targeting Livin were predicted by the online software - TargetScan and miRBase, and then validated by dual luciferase reporter gene assay. We found that post-transcriptional inhibition of Livin occurred in DU145 cells, assumedly due to the miRNA pathway. Among 6 candidate miRNAs, miR-198 expression was identified to be negatively correlated with Livin expression level in some prostate cancer cell lines. Further study revealed miR-198-mediated repression of Livin expression. Therefore, the regulation of Livin expression may involve miR-198 in prostate cancer cell lines.