Abstract： Objective To approach the effects of MMP-9 antisensc oligonucleotide(ASODN)on human lung adcnocarcinoma(A549) cell apoptosis and proliferation capability.Methods MTT.was used to analyze the effect that MMP-9 transfection on A549 cell growth.Flow cytometry was used to analyze the ratio of cell proliferation and apoptosis.RT-PCR WaS used to detect the expression of MMP-9mRNA and Western blot was used to detect the changes of MMP-9 protein.Results In some degree,MMP-9 ASODN that inhibited the survival rate of the A549 cell presented concentration and time dependence manner.The best dependence concentration of ASODN was 600nmol/L for 24 hour.After trasnfection of MMP-9ASODN to A549 cell.the perceive of A549 apoptosis cell was significandy higher than that in control group(P＜0.01).When the antisense oligonucleotides concentration is 600nmol/L and the action time is 48 hours,the relative expression level of MMP-9mRNA and MMP-9 protein are obviously less than that in control group(P＜0.01).Conclusion MMP-9ASODN may down regulate the expression of MMP-9mRNA and MMP-9 protein,effectively inhibit the proliferation of A549 cell and promote the apoptosis of A549 cell.