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.

Expression and Clinical Significance of CD44vin Hum an Gastric Cancers

Expression of CD44v mRNA in 20 patients with gastric tumor was investigated to identify the correlation of the CD44 gene splice and abnormal expression with the clinicopathological changes. The results showed that CD44v mRNA was expressed in 16 of 20 gastric cancers. In 5 out of the 10 mucosa tissues adjacent to gastric cancer, However, no expression of CD44v mRNA was found in all 10 normal mucosa specimens; Positive expression was found in 15 of 16 patients with lymph node metastasis, and 1 out of 4 patients without lymph node metastasis, as well as 5 cases with distant metastasis (P<0.05). Positive expression of CD44v was found in 2 out of 5 well differentiated type gastric cancers, and 14 out of 15 poorly differentiated gastric cancers. Differences were found in the expression between the two types of gastric mucosa (P<0.05). All the mucosa samples including normal gastric mucosa, gastric cancer and its adjacent tissues presented the standard CD44v mRNA. The conclusion was that the abnormal expression of CD44v is a universal significance in gastric cancer, which might serve as an early marker of gastric cancer and metastasis.

The expression and clinical significance of CD44v in human gastric cancers

INTRODUCTIONCD44 was originally implicated as a'homing'receptor directing the migration of recirculatinglymphocytes.CD44 expression has beenconfirmed not only in lymphocytes but also in awide variety of epithelial tissues.It is considered asan important cell adhesion molecule for cell to cellinteractions.Molecular cloning and analysis

PCNA、CD44和nm23基因产物在膀胱癌的表达及临床意义

应用流式免疫法对４５例膀胱癌标本的ＰＣＮＡ、ＣＤ４４ｖ和ｎｍ２３－Ｈ１基因产物的表达进行研究。结果显示，ＰＣＮＡ高表达仅与膀胱癌的浸润程度有关（Ｐ＜０．０５），ＣＤ４４高表达与膀胱癌的浸润程度和复发有关（Ｐ＜０．０５）；而ｎｍ２３－Ｈ１低表达与膀胱癌的浸润程度和复发有关（Ｐ＜０．０５）。提示检测ＰＣＮＡ、ＣＤ４４ｖ和ｎｍ２３－Ｈ１基因产物的表达。

胃癌胃异常增生组织中CD44V_6表达及其意义

目的 探讨转移相关基因CD4 4V6与正常胃粘膜、胃异常增生组织及胃癌组织中某些生物学行为的关系。方法 采用免疫组化SP法 ,检测正常胃粘膜 30例、胃异常增生粘膜组织 30例、胃癌原发灶 84例CD4 4V6的表达。结果 CD4 4V6在正常胃粘膜呈阴性表达 ;胃异常增生粘膜组织、胃癌组织呈阳性表达 ,其中异常增生 2 0 0 0 % ,胃癌中肠型胃癌 (71 4 3% )明显高于弥漫型胃癌 (37 14 % ) (P <0 0 5 ) ;淋巴结转移组(87 87% )明显高于无淋巴结转移 (38 77% ) (P <0 0 5 ) ;CD4 4V6阳性率与肿瘤大小无关 (P >0 0 5 ) ;不同胃癌病理分型中淋巴结CD4 4V6阳性率差异无显著意义 (P >0 0 5 )。结论 CD4 4V6阳性表达同胃癌生物学行为密切相关 ,是预测侵袭与转移有价值的指标。