/Han Lei(韓磊，Dept Neurosurg，Tianjin Med Univ Gen Hosp，Lab Neurooncol，Tianjin Neurol Inst，Tianjin 300052)…∥Chin J Neurosurg.-2011，27(2).-131～135

ObjectiveTo investigate the effect of knocking down Dicer by RNAi on the biological characteristics of human glioma cells U251 in vitro.MethodsThe recombinant adenovirus expression vector which contained short hairpin RNA targeting Dicer(rAd-Dicer)was transfected into U251 cells.The silencing effect of RNAi on Dicer expression was identified by RT-PCR，immumofluorecence staining and Western blot.Western blot was also undertaken to analyze the expression of some functional proteins.The biological behavior changes of U251 cells trasfected by rAd-Dicer were evaluated by MTT，FCM and transwell assay.ResultsrAd-Dicer dramatically down-regulated the expression of Dicer in U251 cells.As compared with parental and rAd-HK transfected cells，the protein expression of p-AKT，MMP2/9，PCNA，Cyclin a，VEGF，CD34 were up-regulated in rAd-Dicer treated cells.Decreased dicer expression in rAd-Dicer transfected cells was accompanied by 14.1%to 15.3%increase in U251 cells in S phase.Meanwhile，the proliferation and invasive activity were significantly enhanced in rAd-Dicer transfected cells by the MTT and transwell assay.ConclusionKnockdown of dicer renders the U251 cells more malignant transformation.This preliminaryfinding suggests that global lowering expression of microRNAs may have an oncogenic role.23 refs，5 figs.