Inhibition of spermine oxidase expression by siRNA decreases sensitivity of human A549 lung cancer line to antitumor polyamine analogue CPENSpm / 中国药理学通报

ABSTRACT

Aim To evaluate the effect of expression inhibition of spermine oxidase(SMO)on the actitumor activity of polyamine analogue CPENSpm (N~1-cyclopropylmethyl-N~(11)-ethylnorspermine).Methods siRNA technique was used to inhibit expression of SMO in human lung cancer line A549.QT-RT-PCR and enzyme activity assay was performed to determine the expression level of SMO.The cell proliferation was detected by MTT assay.The apoptosis of A549 cells were evaluated by DNA degradation and Sub-G_1/flow cytometry assay.Results The A549 cell line with silenced SMO expression was successfully obtained.Basic SMO mRNA and enzyme activity levels in the SMO-siRNA plasmid transfected cells were 0.53% and 14% lower than that in the control cells respectively. Treating A549 control cells by 10 μmol·L~(-1) CPENSpm for 24 hours resulted in a 10-folds up-regulation of SMO in mRNA level and 20-fold increase in enzyme activity,but this drug-induced SMO expression was obviously prevented in SMO-siRNA plasmid transfected cells.MTT assay demonstrated that SMO expression inhibition decreased the sensitivity of A549 cells to CPENSpm exposure(0～20 μmol·L~(-1)).DNA degradation and sub-G_1 assay proved a deceased ability of CPENSpm to induce apoptosis in SMO-siRNA plasmid transfected cells.Conclusion Up-regulation of SMO by CPENSpm is possibly one of the molecular basics for its antitumor activity.