For instance, Fujita et al. (2008) demonstrated that miR-34a expression is downregulated in PC3 and DU145 prostate cancer cells, and ectopic expression of miR-34a downregulates SIRT1 protein expression in PC3 prostate cancer cells at the transcriptional level (that is, via reduction of SIRT1 promoter activity) but not at the post-transcriptional level (that is, via interaction with SIRT1 3′-UTR). This evidence concerns the gene SIRT1 and prostate cancer.