Atorvastatin (ATO), a widely used statin for lowering cholesterol was examined for its chemopreventive/therapeutic activities in prostate... Show moreAtorvastatin (ATO), a widely used statin for lowering cholesterol was examined for its chemopreventive/therapeutic activities in prostate cancer cells. We found that ATO inhibited cell proliferation and induced autophagy in PC3 prostate cancer cells, as marked by significant induction of an autophagy marker LC3-II. Using Taqman RT-PCR technique, we also found that ATO treatment for 24h and 48h consistently up-regulated miR-182 in PC3 cells. However, adding geranylgeraniol (GGOH) to the culture media reversed the effect of ATO in regulating miR-182, suggesting that ATO up-regulates miR-182 through inhibition of geranylgeranyl biosynthesis. Overexpression of miR-182 in PC3 cells significantly decreased cell proliferation by about 36% (MTT assay), while knock-down of miR-182 stimulated cell proliferation by about 43% (MTT assay). In screening for miR-182 target genes, we found that Bcl2 and p21 are potential miR-182 target genes; Bcl2 was significantly down-regulated by ATO at both mRNA and protein levels and miR-182 knock-down up-regulated Bcl2 protein; p21 protein expression was positively correlated with alteration of miR-182 expression levels in PC3 cells. Through screening database of miR-182 target genes from TargetScanHuman 6.2 and PicTar, we found that p21 is not the direct target gene of miR-182, so it could be regulated by miR-182 indirectly. It has recently been established that miR-182 regulation is p53-dependent, since PC3 cells are p53 negative, it is clear that ATO regulates miR-182 in a p53-independent manner. These data demonstrate that miR-182 up-regulation and Bcl2 down-regulation by ATO could be two independent events and both could be involved in ATO mediated cell proliferation and autophagy. M.S. in Biology, May 2013 Show less
