RESUMO
<p><b>OBJECTIVE</b>To study the inhibition of the expression of bcl-xL gene induced by RNA interference in CNE-2Z cell line in addition to the inhibition of its proliferation and apoptotic induction.</p><p><b>METHODS</b>Small interfering RNAs targeting bcl-xL gene were synthesized by using web design software provided by Amnion and the silencer short interfering RNA (siRNA) construction kit; fluorescein-labeled siRNAs were done by FAM-silencer siRNA labeling kit; siRNAs were transfected into CNE-2Z cells by using lipofectamine 2000 reagent; siRNA transfection efficiencies were analyzed by fluorescent microscopy; down-regulation of bcl-xL was detected by RT-PCR; thiazolyl blue (MTT) assay was used to assess the cell growth; apoptosis of CNE-2Z cells was analyzed by flow cytometry.</p><p><b>RESULTS</b>Green fluorescence in the cells was seen clearly in FAM-labeled siRNA transfected group under the fluorescent microscope while none in the untransfected group. Different down-regulations of bcl-xL mRNA expression were found in the transfected groups. The expression of bcl-xL mRNA decreased by 10% - 70% in the siRNAs transfected CNE-2Z by RT-PCR scan analysis. The inhibitory rate of cell proliferation depended on time and concentrations to some extent. Different cell apoptosis could be induced by different concentrations of siRNA4.</p><p><b>CONCLUSIONS</b>The synthesized siRNAs in vitro were able to down-regulate the expression of bcl-xL There were different capabilities of the specific siRNAs down-regulation. The transient transfected bcl-xL siRNA4 could effectively inhibit the growth of the cancer cells and induce theirs apoptosis. It was suggested that the siRNA technique provide not only an extremely powerful tool for the functional analysis of genome but also a new method for anti-nasopharyngeal carcinoma gene therapy.</p>