Objective      To construct an eukaryotic expression vector of ribonuclease inhibitor (RI) gene

pcDNA3.1-RI

and to investigate the effect of pcDNA3.1-RI on the growth of human umbilical vein endothelial cells (HUVECs) and the relationship between RI and angiogenin (ANG).       Methods      RI gene segments amplified by RT-PCR and digested by restriction enzym

es were inserted into pcDNA3.1 to construct the recombinant vector pcDNA3.1-RI

which was transferred into HUVECs by liposomes. The mRNA levels of RI and ANG were detected by RT-PCR

and the protein expression levels of RI

ANG

MMP-2 and MMP-9 were detected by Western blotting. The interaction between ANG and RI was examined by co-immunoprecipitation (Co-IP). The proliferation activity of HUVECs was detected by MTT assay

and cell cycle distribution was detected by flow cytometry.       Results      The recombinant vector pcDNA3.1-RI was successfully constructed. The mRNA and protein expression of RI in the experimental group (HUVECs transfected with pcDNA3.1-RI) significantly increased as compared with that in the control group (HUVECs transfected with pcDNA3.1) and in the blank control group (P0.05). The mRNA and protein expression of ANG decreased in the experimental group

and MMP-2 and MMP-9 protein expression decreased as well (P0.05). In the experimental group

cell proliferation activity of HUVECs significantly decreased (P0.05)

and the cells were arrested at G

1

-S phase. The Co-IP detected the interaction between ANG and RI.       Conclusion      Eukaryotic expression vector pcDNA3.1-RI is constructed successfully

and it can increase the mRNA and protein expression of RI. RI can interact with ANG and downregulate ANG expression at the transcription level to inhibit the proliferation and migration of HUVECs.