Objective     To construct the specific siRNA vector with a high performance for inhibiting the expression of human positive co-activator 4（PC4）.      Methods     Four pairs of PC4 specific siRNA interfere targets were designed and synthesized. They were then cloned into the PSES-HUS adenovirus shuttle plasmid to construct recombinant pSES-HUS-PCi1

pSES-HUS-PCi2

pSES-HUS-PCi3

and pSES-HUS-PCi4 plasmids which were packaged with lipid bodies and transiently transfected into 293T cells. Effect of the 4 plasmids on expression of PC4 mRNA and protein was detected by real time quantitative PCR（qRT- PCR）and Western blotting

respectively. Optimal recombinant plasmids and interfere targets were screened

and their effect on proliferation and migration of 293T cells  was studied by cell scratch test.      Results     The 4 constructed pairs of recombinant plasmid vectors were identified by enzyme digestion and analyzed by gene sequencing. Their size and sequences were consistent as expected. The 4 constructed pairs of recombinant plasmids and pSES-HUS-PCi1 empty plasmids were used to transfect 293T cells. The expression level of PC4 mRNA and protein was lower in recombinant pSES-HUS-PCi1 plasmids than in pSES-HUS-PCi1 empty plasmids and normal 293T cells (P0.01)

indicating that the PC4 target sequences of recombinant pSES-HUS-PCi1 plasmids（sense: 5′-AACAGAGCAGCAGCAGCAGATTTT-3′; antisense: 5′-ATCTGCTGCTGCTGCTCTGTTTT-3′）can inhibit the expression of PC4 mRNA and synthesis of proteins (P0.01)，with an inhibitory rate of 85.30% at mRNA level and 80.57% at protein level

respectively. The in vitro proliferation and migration of 293T cells were decreased

especially in recombinant pSES-HUS-PCi1 plasmids

when the expression of PC4 was interfered (P0.05).      Conclusion     The siRNA vector for specific inhibition of PC4 expression with a high performance has been successfully constructed and PC4 can influence the proliferation and migration of 293T cells in epithelium.