Background: RNA interference (RNAi) is sequence specific inhibition of gene expression induced by doublestranded RNA.
Objective: Define the role of Wilms tumor 1 gene (WT1) in breast cancer oncogenesis using RNAi.
Material and Method: MCF-7 breast cancer cells, which express a high level of WT1, were transfected with synthetic small interfering RNA (siRNA) targeting WT1 (siRNAWT1) resulting in inhibition of WT1 expression, as well as growth, in a dose- and time-dependent manner.
Result: The minimum concentration of siRNAWT1 for growth inhibition and WT1 silencing was 25 nM and 50 nM respectively. WT1 expression was completely abolished at 200 nM siRNAWT1.
Conclusion: These data suggest that WT1 is indispensable for the survival of breast cancer MCF 7 cell line.

Keywords: RNA interference, WT1, MCF-7, Breast cancer