Background: Breast cancer is the most common cancer among women worldwide which are diagnosed. Despite many advances in clinical and therapeutic procedures in recent years, many cancer patients still suffer from recurrence and metastasis after surgery. Thus, new treatments and advanced on ineffective treatments has overcome tumor cells. miRNA-21 reduces tumor suppressor protein expression and protein expression of oncogenes is increased. The aim of this study was to determine the expression level of snail1, microRNA-21 and MMP-9 in breast cancer cell line MDA-MB-468 after suppression of gene expression by snail1 small interfering RNA (siRNA). Methods: Cells were transfected with snail1gene specific siRNA. And total RNA was extracted. In the next stage cDNA was produced by using of proper primer to specific gene. Then the mentioned gene was amplified by qRT-PCR technique. The relative expression of gene was evaluated to beta-actin gene as an internal control. Not treated tumor cells with siRNA were set as an external control. Results and Conclusion: transfecting of siRNA specific to snail 1 gene, reduced the expression level of snail1, miR-21 and MMP-9 significantly in a dose of 60 picomol and treatment time48 hours according to control group. It is concluded that the method of gene silencing by siRNA can be used to treat metastatic breast cancer cells.
