RESUMEN
<p><b>OBJECTIVE</b>To investigate the role of small interfering RNA (siRNA) targeted to survivin in combination with 5-fluorouracil (5-FU) in inhibiting the proliferation of MCF-7 cells.</p><p><b>METHODS</b>A siRNA targeted to survivin was synthesized and transfected into MCF-7 cells via lipofectin. Changes of the cell growth activity in response to combined treatment with survivin siRNA and 5-FU or 5-FU treatment alone was evaluated by MTT assay. The Q method of Jin Zhenjun was used to evaluated synergism between the synthesized siRNA and 5-FU.</p><p><b>RESULTS</b>Treatment with 5 nmol/L siRNA reduced the IC50 of 5-FU from 4.42 to 1.18 microg/ml, and the inhibitory effect of combined treatment on MCF-7 cells was higher than that of 5-FU alone (F=26.74, P<0.01). Synergism effect was observed between 5-FU at lower concentrations and survivin siRNA.</p><p><b>CONCLUSION</b>siRNA may enhance the effectiveness of 5-FU in inhibiting the proliferation of MCF-7 cells.</p>