[The effect of siRNA-Her2/neu on the drug sensitivity of Her2/neu-overexpressing lung adenocarcinoma cell line].

ABSTRACT

OBJECTIVE: To explore the effect of synthesized siRNA targeting Her2/neu oncogene on the drug sensitivity of Her2/neu-overexpressing lung adenocarcinoma cell line. METHODS: The experiments consisted of four groups including an untreated control group, an empty vector group, an unrelated siRNA group, and a Her2/neu siRNA group. Every experiment was repeated five times. Lung adenocarcinoma cell line Calu-3 was transfected with siRNAs formulated LipofectAMINE 2000, and Her2/neu protein and P-gp of each group were determined by flow cytometry (FCM). The chemosensitivity of transfected cells to cisplatin (DDP) was measured by MTT. Cell apoptosis detection kit (Annexin V method) was used to examine the drug induced apoptosis rate. RESULTS: The Her2/neu protein and P-gp positive expression rate in the Her2/neu siRNA group, the untreated control group, the empty vector group and the unrelated siRNA group were [(25.04 +/- 1.56)%, (4.24 +/- 1.01)%], [(98.24 +/- 2.23)%, (5.11 +/- 2.98)%], [(95.67 +/- 1.98)%, (6.98 +/- 2.47)%] or [(94.79 +/- 0.87)%, (5.59 +/- 3.66)%], respectively. Introduction of the sequence specific siRNA into Her2/neu positive Calu-3 cells in vitro greatly reduced the cell surface expression of the Her2/neu protein, but had no effect on P-gp level. Consequently the inhibitory rate of DDP in combination with siRNA targeting Her2/neu was (67.1 +/- 2.3)%, but it was (48.1 +/- 3.5)%, (46.3 +/- 5.9)% and (50.2 +/- 2.9)% in the untreated control, the empty vector and the unrelated siRNA groups, respectively. There was a significant difference between Her2/neu siRNA group and other three groups (P < 0.01). The FCM results showed the apoptosis rate of DDP combined with siRNA-Her2/neu was elevated as compared with the unrelated siRNA group, the empty vector group or the untreated control group. CONCLUSION: Sequence specific siRNA-Her2/neu was capable of enhancing the chemosensitivity of Calu-3 cells to cisplatin.