The Inhibitory Effect Of MIF SiRNA On The Expression Of VEGF In Hepatocellular Carcinoma Cells

Objective To investigate the inhibitory effect of macrophage migration inhibitory factor(MIF)small interfering RNA(siRNA)on the expression of vascular endothelial growth facto(rVEGF)in hepatocellular carcinoma cells and discussion the effection of MIF in tumori-angiogenesis.Methods The expression of MIF,VEGF and p-MAPK in 4 pairs HCC tumor tissues (T)and their peri-tumor tissue(sP) was initially detected to provide evidence of simultaneous MIF and VEGF overexpression in HCC tissues . Specific small interfering RNA targeting MIF gene was chemically synthesized, and then was transfected at the doses of 50nmol/L and 100nmol/L into HCC cell lines of PLC and HepG2 with lipofectamine 2000 methods. The control groups of PLC and HepG2 were transfected with the control siRNA. The expression of MIF and VEGF mRNA and MIF,VEGF and p-MAPK protein were examined by quantitative real-time PCR and western blot after siRNAs treatment, respectively. The results were compared with the control groups and between the experimental groups.Results MIF and VEGF were overexpressed in the HCC tumor tissues compared with the peri-tumor tissues (P<0.01). The expression levels of p-MAPK protein were also higher in tumors than in the corresponding adjacent nontumor tissues. In MIF siRNA treated PLC and HepG2 cells, the mRNA and protein expression of MIF were significantly decreased in a dose-dependent manner. VEGF mRNA was observed to be significantly down-regulated in MIF siRNA treated PLC and HepG2 cells when compared with the control groups(P<0.01). In 50nmol/L and 100nmol/L groups, MIF,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 cell and (74.3±8.9)%,(65.6±4.6)% and(88.4±4.6)%,(80.7±2.2)% in HepG2 cell. To be compared with the control groups, MIF,VEGF protein levels were significantly reduced in the experimental groups(P<0.01)and a statistically significant difference of the protein expression were also found between the two different doses groups of MIF siRNA treated HCC cells(P<0.05). After PLC and HepG2 were treated with MIF siRNA for 24 hours, the tyrosine phosphorylation of MAPK was found that markedly suppressed in a dose-dependent manner,the expression of p-MAPK in PLC and HepG2 cell lines decrease 48.6%, 79.7% and 45.7%, 64.2% in siRNA 50nM and 100nM group, respectively, and there are also significant difference between siRNA 50nM group and siRNA 100nM group.Conclusions MIF and VEGF protein and mRNA were overexpression in HCC tumor tissues.MIF siRNA was able to specifically knock down the expression of MIF and it could also 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 through the ERK-MAPK signalling.