巨噬细胞移动抑制因子小干扰RNA对肝癌细胞表达血管内皮生长因子的抑制效应

The inhibitory effect of MIF siRNA on the expression of VEGF in hepatocellular carcinoma cells

目的观察巨噬细胞移动抑制因子（MIF）小干扰RNA（siRNA）对肝癌细胞表达血管内皮生长因子（VEGF）的影响。方法Western blot检测MIF和VEGF在肝癌和癌旁组织的表达情况；人工化学合成MIFsiRNA和对照siRNA，将其转染PLC、HepG2肝癌细胞株，定量聚合酶链反应（PCR）和Western blot检测MIF和VEGFmRNA及其蛋白的表达。结果MIF、VEGFmRNA和蛋白在肝癌组织中高表达。MIFsiRNA（50、100nmol／L）转染肝癌细胞株后，PLC细胞MIF和VEGFmRNA水平分别下调（78．8±7．2）％、（90．4±2．9）％和（60．6±2．6）％、（79．8±1．2）％；HepG2细胞MIF和VEGFmRNA水平分别下调（74．3±8．9）％、（88．4±4．6）％和（65．6±4．6）％、（80．7±2．2）％。MIF蛋白分别下调（57．3±3．4）％、（78．7±1．2）％和（54．8±6．8）％、（77．9±2．3）％，并呈剂量依赖关系；伴随MIFmRNA和蛋白的表达下调VEGF蛋白分别下调（52．6±12．9）％、（87．4±2．3）％和（52．4±11．1）％、（68．5±2．8）％，亦呈剂量依赖关系，与对照组比较差异有统计学意义（P〈0．01），两干预组间的差异也有统计学意义（P〈0．05）。结论MIFsiRNA能特异性阻断PLC及HepG2细胞MIFmRNA和MIF蛋白的表达，并且同时有效下调VEGFmRNA及其蛋白的表达，MIF可能通过调控VEGF基因和蛋白的表达，参与肿瘤血管的生成和促进肿瘤细胞的转移。

Objective To investigate the inhibitory effect of macrophage migration inhibitory factor （MIF） small interfering RNA （siRNA） on the expression of vascular endothelial growth factor （VEGF） in hepatocellular carcinoma （HCC） cells. Methods The expression of MIF and VEGF in 4 HCC tumor tissues （T） and their peri-tumor tissues （P） was initially detected to provide evidence of simultaneous MIF and VEGF overexpression in HCC tissues. Specific small interfering RNA （ siRNA ） targeting MIF gene was chemically synthesized, and then transfected at the doses of 50 and 100 nmol/L into HCC cell lines of PLC and HepG2 with Lipofectamine 2000. The control groups of PLC and HepG2 were transfected with the control siRNA. The mRNA and protein expression of MIF and VEGF after siRNAs transfection was examined by quantitative real-time PCR and Western blot. Results MIF and VEGF were overexpressed in the HCC tumor tissues compared with the peri-tumor tissues （P 〈0.01 ）. In MIF siRNA transfected PLC and HepG2 cells,the mRNA and protein expression of MIF was sigrLificantly decreased in a dose-dependent manner. VEGF mRNA was significantly down-regulated in MIF siRNA transfected PLC and HepG2 ceils as compared with the control groups （P 〈0.01 ）. In 50 and 100 nmol/L groups, MIF and VEGF mRNA levels were respectively decreased by （78.8 ±7.2）%, （60.6±2.6）% and （90.4 ±2.9）%, （79.8 ± 1.2）% in PLC cells,and （74.3±8.9）%,（65.6 ±4.6）% and （88.4±4.6）% ,（80.7 ±2.2）% in HepG2 cells,respectively. As compared with the control groups, MIF and VEGF protein levels were significantly reduced in the experimental groups （P 〈 0. 01 ） and a statistically significant difference in the protein expression was also found between the two different doses groups of MIF siRNA transfected HCC cells （P 〈0.05）. Conclusion MIF siRNA could specifically knock down the expression of MIF and efficiently suppress the expression of VEGF in PLC and HepG2 cells. Maybe MIF participate in tumor angiogenesis and enhance carcinoma metastasis via modulation of VEGF gene and protein expression.