OBJECTIVETo investigate the effect of miRNA silencing HIF-1α gene on the proliferation of HepG2 cells.

METHODSThe eukaryotic expression plasmids of HIF-1α miRNA and report gene containing hypoxia-reponse element were constructed and transfected into HepG2 cells. The expressions of HIF-1α gene and protein were determined by real time-PCR and Western blotting. The expressions of HIF-1α, vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2) were quantitatively detected by ELISA. The alterations of cell cycles and apoptosis rate were quantitatively measured by flow cytometry and Annexin V-FITC/PI double dyeing assay.

RESULTS72 h after transfection the down regulations of HIF-1α mRNA and protein were 87% and 56% respectively, and the decrease of target gene was 46% in the report gene, 54% in VEGF and 36% in Ang-2, respectively. The apoptotic ratio of HepG2 cells was 22.46+/-0.61% (P < 0.01). The cell cycle changed greatly at the ratio of G1 (61.49+/-1.12%) and S (22.40+/-0.58%, P < 0.01). After being combined with doxorubicin, the apoptotic ratio increased to 36.99+/-0.88% and the ratios of G1 and S phases were upregulated to 65.68+/-0.91% and 19.47+/-1.34% respectively.

CONCLUSIONSHIF-1α miRNA or / and doxorubicin can regulate the growth cycles of HepG2 cells, promote the cell apoptosis and inhibit the cell proliferation.