[Influence of RNA interference on MSI-2 gene in THP-1 cell and expression of NUMB]

To investigate the effect of small interfering RNA（siRNA）for MSI-2 on the growth, apoptosis and NUMB expression of THP-1 cells.

Three siRNA for MSI-2 gene was designed and transfected into THP- 1 cells. The cell inhibition, colony formation and apoptosis were determined. The protein expression of NUMB, caspase- 3 and PARP were detected by Western blotting.

After MSI- 2 expression of THP- 1 cells was down- regulated for 24 hours, cell inhibition of siRNA MSI-2 group was（47.89±7.64）%, obviously higher than that of negative control group（P=0.005）. After 9 days, cell colony count of siRNA MSI-2 group was 7.50±1.53, also lower than that of negative control group（35.75±7.46, P<0.001）. In addition, apoptotic rates of siRNA MSI- 2 group at 24 hours ［（15.22±1.52）%］and 48 hours［（33.83±3.96）%］were significantly higher than those of negative control group（P=0.008 and P=0.001, respectively）. Accordingly, activations of caspase-3 and PARP and increased NUMB were observed in siRNA MSI- 2 group.

siRNA for MSI- 2 gene could increase the expressions of NUMB to inhibit the proliferation and induce apoptosis of THP-1 cells.