Objective To create Mucin gene 1 (MUC1) antisense peptide nucleic acid (PNA),and to observe its effects on MKN-45 cell invasion and explore the mechanism. Methods The sequence of antisense PNA was designed according to MUC1 gene sequence and transfected into human gastric cancer cells (MKN-45) by liposome,and the empty vector group (randomized control group)and blank control group (negative control group) were involved. The expression of MUC1 was detected by real time quantitative PCR and the changes of E-cadherin expression were also observed.The effects on gastric cancer cell invasion were tested with transwell chamber assays.Results The expression of MUC1 gene was effectively suppressed by the 3 created antisense PNA,and their expression level (0.62±0.18,0.49±0.12 and 0.60±0.21) was significantly lower than that of negative control group (1.18 ± 0.03,P ＜ 0.01). There was no significant difference between radomized control group and negative control group (1.00±0.04,P=0.657).After MUC1 PNA transfected,the capability of gastric cancer cell invasion decreased significantly (P=0.005).And the expression of E-cadherin at mRNA and protein level was up-regulated.Conclusions There is negative correlation between MUC1 and E-cadherin expression in gastric cancer cell MKN-45.The capability of tumor cell invasion is significantly inhibited by suppressing MUC1 gene expression.