Objective      To determine the effect of metastasis associated in colon cancer 1 (MACC1) knockdown by RNA interference (RNAi) on the proliferation and migration in breast cancer cells.       Methods      The fluorescently-labeled siRNA-FAM targeting MACC1 gene was chemically synthesize

d

and then transfected into human breast cancer cell line MCF-7 by siRNA transfection reagent. Inhibitory efficiency of MACC1 expression at mRNA and protein levels was examined by RT-PCR and Western blotting respectively. Moreover

MTT assay was applied to assess the influence of specific MACC1 siRNA on the cell growth. Transwell chamber test was used to observe the cell migration ability. Furthermore

downstream migration-related targets of MACC1

S100A4 and vimentin were measured in MCF-7 cells by Western blot analysis.       Results      MACC1 was strongly expressed in MCF-7 cells. Transfection of specific MACC1 siRNA-FAM resulted in a highly-efficient declined expression of MACC1

accounting for 81% at mRNA and 75% at protein levels respectively after 48 hours’ transfection. Specific siRNA-FAM of MACC1 also suppressed cell proliferation in a time-dependent manner

with significant differences for the cells after transfection for 24

48 and 72 h compared with the cells without transfection (

P

0.05). Transwell chamber test showed that there were less cells migrated through the membrane in the transfected cells than in the control (

P

0.05)

indicating specific MACC1 siRNA-FAM decreasing migration ability in MCF-7 cells. But

no difference was found in migration ability in the blank control and negative control cells (

P

0.05). Knockdown of MACC1 expression inhibited the expression of S100A4 and vimentin protein in MCF-7 cells (

P

0.05).       Conclusion      Specific siRNA targeting MACC1 efficiently inhibits the proliferation and migration in MCF-7 cells

which might be through down-regulating S100A4 and vimentin.