Polyethylenimine (PEI) was utilized as a carrier for mediating anti-apoptotic siRNA (siSurvivin)

which could silence the expression of survivin gene.The siSurvivin was used with an antitumor drug (cisplatin) for synergistic antitumor treatment.The siRNA binding capacity of PEI was evaluated by gel retardation assay

and the complete formation of PEI/siRNA was achieved at the weight ratio of 0.4.The drug resistant ability was found to be eightfold higher in resistant cells compared with the sensitive cells

and the survivin gene was overexpressed in A549DDP cells.RT-PCR experiment proved that PEI/siSurvivin complex was capable of achieving an effective silencing effect of survivin gene

and the silencing effect did not change after the cisplatin was added.Cell apoptosis assay showed that the synergistic effect of cisplatin and gene could achieve a significant apoptosis rate of 60.9%

while cisplatin or PEI/siSurvivin complex was used alone

only about 30.2% and 19.8% of apoptosis rate could be obtained

respectively.Cell proliferation assays could further validate the effective synergistic antitumor effect of cisplatin and siSurvivin mediated by PEI.