PEI-PEG as a siRNA Genetic Vector Demonstrating Interference in the Expression of CD44v6 Protein in Gastric Cancer Cells

OBJECTIVE To investigate the effect of polyethylene imine glycol （PEI-PEG）/siRNA nanocomposites in the in vitro transfection of human gastric cancer SGC7901 cell lines and the down-regulation of gene expression of the adherence factor CD44v6. METHODS PEI-PEG/siRNA nanoparticles, in different N/P ratios, were synthesized and transfected into gastric cancer cells. Lipo2000/siRNA was used in the control group. The transfection efficiencies were observed under fluorescence microscope. The cytotoxicity of the nanoparticles was measured using the MTT assay （mononuclear cell direct cytotoxicity assay）, and the down-regulation effect of siRNA on CD44v6 gene was evaluated by Western blot. Based on the different N/P ratios, PEI-PEG/siRNA composites were synthesized and transfected into gastric cancer cells. Lipo2000/siRNA was used in the controls. The transfection efficiency was observed under fluorescence microscope. The cytotoxicity of the nanoparticles was measured using the MTT assay and the down-regulation effect of siRNA on CD44v6 gene was evaluated by Western blot. RESULTS After transfection, the transfection efficiency of the PEI-PEG/siRNA nanocomposites increased incrementally in N/P ratio value. The transfection efficiency improved with an increase in N/P ratio. When the N/P value was 15, fluorescence became more intense in the PEI-PEG/siRNA group than in the Lipo2000/siRNA group. At the same time, cell viability was （80.4 ± 5.6）% in the MTT reduction assay, which was similar to that in the Lipo2000/siRNA group. The results of Western blot analysis showed that the expression level of CD44v6 protein decreased to （59.7 ± 3.0）% after siRNA-CD44v6 was inhibited. CONCLUSION PEI-PEG could effectively form the nanocomposite in combination with siRNA, be transfected into the SGC7901 gastric cancer cell lines and inhibit CD44v6 protein expression. Moreover, as a genetic carrier, PEI-PEG copolymer has greater advantages, including high transfection e. ciency, less cytotoxicity and an easily alterable vector structure.

maspin CD_(44)V_6在非小细胞肺癌中的表达及意义

目的:探讨maspin及CD44V6在非小细胞肺癌(NSCLC)组织中的表达及临床意义,分析maspin与CD44V6的表达有无相关。方法:应用免疫组织化学PictureTM通用型二步法检测94例NSCLC组织、54例正常支气管粘膜组织、28例肺良性病变中maspin和CD44V6的表达情况。结果:maspin在正常支气管粘膜组织及肺良性病变中的阳性表达率分别为100%和89.28%,在肺癌组织中的阳性表达率为54.26%,正常支气管粘膜组织与肺癌之间、肺良性病变与肺癌之间的阳性表达率差异有显著意义(P<0.05),maspin阳性表达率与NSCLC临床分期、淋巴结转移成负相关,与病理类型、组织分化程度无关。CD44V6在NSCLC中的阳性表达率68.09%,与临床分期、淋巴结转移成正相关,与病理类型、组织分化程度无关;而在正常支气管粘膜组织及肺良性病变中无阳性表达。maspin基因表达与CD44V6呈负相关(r=-0.213,P<0.01)。结论:maspin和CD44V6在肺癌的发生、发展、转移过程中发挥调控作用,可作为判断肺癌预后和转移的重要生物学指标。