Abstract： Objective To investigate the effects of integrin β1 gene expression inhibited by short hairpin RNA (shRNA) on invasion of pancreatic carcinoma PANC1 cells in vitro,and investigate the mechanism.Methods The eukaryotic expression plasmid of shRNA targeting integrin β1 gene ( integrin β1 shRNA) and control eukaryotic expression plasmid shRNA (c-shRNA) was constructed and was transfected into PANC1 cells.The cells without plasmid transfection were used as control.The expressions of integrinβ1,MMP 2,MMP 9 mRNA and protein were detected by real-time PCR and Western blotting.The invasive ability of PANC1 cells was observed with Transwell cell culture chamber.Results Integrinβ1 mRNA expressions in integrinβ1 shRNA group,c-shRNA group and control group were 0.0029 ± 0.0004,0.0131 ± 0.0009,0.0138 ± 0.0005 ; the expressions of integrinβ1 protein were 0.0159 ± 0.0062,0.3215 ± 0.0126,0.3107 ±0.0094; the inhibitory rate of integrinβ1 mRNA and protein expression in integrinβ1 shRNA group was (78.6 ±7.2 ) ％ and (92.9 ± 3.2) ％ ( P ＜ 0.01 ).But there was no difference between the c-shRNA group and control group (P =0.2999).Number of penetrating cells in integrinβ1 shRNA group decreased from 52 ±5 to 21 ±4( P ＜ 0.01 ) ; the expression of MMP 2 and MMP 9 mRNA decreased from 0.592 ± 0.073,0.847 ± 0.069 to 0.102 ± 0.034,0.273 ± 0.071 ; the expression of M MP2 and MMP 9 protein decreased from 0.225 ± 0.046,0.416 ±0.081 to 0.059 ±0.013,0.106 ±0.022(P ＜0.05).Conclusions Recombinant integrinβ1 shRNA expression plasmid can effectively inhibit the expression of integrinβ1 gene and suppress the invasion of PANC1 cells in vitro by down-regulating MMP 2 and MMP 9 gene expression.