| Operation,chemotherapy and radiotherapy is the main methed to deal with the lung cancer at present. Chemotherapy and chemotherapy related therapy play an important role in the treatment of lung cancer. The important factor to influence the therapy effects of lung cancer is drug tolerance. Apoptosis obstruction resulting from abnormal genes expression in lung cancer cells is the main reason leading to drug tolerance. Survivin gene is one of the members in Inhibited Apoptosis Protein family. Its abnormal expression often lead to tumorigenesis, progression and drug resistance. There is little report about the role of survivin gene expression during the course of drug resistance in lung cancer both in and outside china. Now it is a hot spot to suppress the apoptosis inhibited genes expressed in tumors and enhance the chemotherapy drug effects. RNA interference is a physiological phenomenon to keep organism heritage stabilization and control epigenotype mutation. As antiquated conservation mechanisms, RNAi can not only resist the exogenous detrimental genes intrusion, but also bring new breakthrough in the research of multitude domain such as functional genomics and gene therapeutics as a technique. At present, RNAi may be become a tumor gene therapy regimen theoretically. Inhibition of survivin expression by use of RNAi and to inhance the drug sensibility may be bringing a new idea in lung cancer therapy.ObjectiveTo investigate the relationship between chemoresistance and the expression of survivin in lung cancer cell A549; to investigate the effects of survivin-specific siRNA on chemosensitivity of lung cancer cell A549 to gemcitabine in vitro. MethodsFor determing if survivin-specific siRNA could enhance the responsiveness of lung cancer to gemcitabine, human lung adenocarcinomo cell lines A549 (p53 wide-type) were divided into four different treatment groups: survivin siRNA, gemcitabine, survivin siRNA+ gemcitabine and control. Human lung adenocarcinomo cell lines A549 were treated with artificial composite survivin -siRNA. The effcets on cell proliferation, cell cycle and survival were analyzed by MTT assay and flow cytometry, respectively.The protein expression levels of survivin were evaluated by immunohistochemistry.ResultsThe MTT result showed : the average absorbance of the survivin siRNA group was 0.214±0.125,the average absorbance of the gemcitabine group was 0.197±0.009,the average absorbance of the survivin siRNA+ gemcitabine group was 0.140±0.006,the average absorbance of the control group was 0.261±0.161.The proliferation rate of the survivin siRNA group was (82.03±4.77)% (F=155.681,P=0.000),the proliferation rate of the gemcitabine group was(75.46±3.76)% (F=275.598, P=0.000),the proliferation rate of the survivin siRNA+ gemcitabine group was (53.71±2.36)% (F=1.414, P=0.244) . A combination of 100 nmol/L survivin siRNA and 10ug/mL gemcitabine at 48h exhibited a better inhibitory effect on the proliferation of A549 cells. The immunohistochemistry result showed: Survivin proteinum was buffy particle, most lied in cell endochylema. The protein expression levels of survivin of the siRNA group and the survivin siRNA+ gemcitabine group was silenced effectively. The FCM result showed : The survival rate of the survivin siRNA group was (22.34±3.41)%,compared with the control group F=6.872,P=0.031, the survival rate of the gemcitabine group was(10.16±0.61)%,compared with the control group F=89.520, P=0.000, the survival rate of the survivin siRNA+ gemcitabine group was (4.84±1.99)%, compared with the control group F=0.131,P=0.727. Compared with the control group, the cell cycle of the survivin siRNA group: G1 stage(72.31±0.64)%,(F=7.852,P=0.023), S stage (14.58±1.91)%, (F=0.900,P=0.371),G2 stage (13.11±1.27)%, (F=21.505, P=0.002); the cell cycle of the gemcitabine group : G1 stage (67.81±4.19)%, (F=34.310, P=0.000),S stage (28.06±4.49)%, (F=80.177,P=0.000),G2 stage (4.13±0.98)%, (F=139.884, P=0.000); the cell cycle of the survivin siRNA+ gemcitabine group: G1 stage (66.79±2.79) % (F=4.462, P=0.068) , S stage (32.35±2.97) % (F=2.546, P=0.149),G2 stage (0.86±0.78)%(F=113.105, P=0.000).Gemcitabine associated with survivin siRNA moderately decreased survival rate compared to either treatment alone.Treatment with survivin siRNA and gemcitabine also produced an increase in the S fraction,and a decrease in the G2 fraction. Survivin-specific siRNA raised the chemosensitivity of gemcitabine.ConclusionThe present study suggests that survivin expression play a critical role in cell viability, and that Survivin-specific siRNA can silence the protein expression level of survivin effectively. Inhibition of survivin by siRNA significantly enhances the cheosensitivity of lung cancer cells to gemcitabine. |
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