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.

CD_(44)V_6基因在前列腺癌组织中的表达及其意义

目的 探讨CD4 4V6 基因与前列腺癌 (PCa)的发生、转移及预后的关系。方法 采用S P免疫组织化学方法检测 82例PCa组织中CD4 4V6 基因的表达情况。结果 CD4 4V6 基因在前列腺癌中有较高的表达 ,阳性率为 46 3 % (38/82 ) ,其中伴盆腔淋巴结转移或骨转移者阳性率为62 5 % (1 5/2 4 ) ,无转移者阳性率 37 9% (2 3/58) ,两者具有显著性差异 (P <0 0 1 )。CD4 4V6 在PCa组织中的高表达还与癌组织的Gleason评分及预后有关 (P <0 0 5)。结论 具有CD4 4V6 高表达的PCa具有更强的浸润和转移能力 ,恶性度较高 ,分化较差 ,CD4 4V6 可作为判断预后及指导术后治疗的一项重要指标。