Abstract: Abstract：Objective To investigate the effect of up-regulation of microRNA-155 (miR-155) on the proliferation of hepatoma cell line HepG2 by constructing lentivirus (LV) overexpressing miRNA-155. Methods The specific miR-155 overexpressing fragment was synthesized into the target sequence and cloned into the lentiviral vector pGCSHL-GFP. The recombinant miR-155-hRNA-LV and the negative control empty viral vector were transfected into HepG2 cells to establish stable overexpression miR-155 cell line. The miR-155 cells were divided into three groups including the overexpression group (H group), the negative control group (negative control, NC group) and the normal group (normal, N group). Real-time fluorescent polymerase chain reaction (qRT-PCR) was used to detect the expression levels of miR-155 and PTEN in three groups. Western blot assay was used to analyze relative expressions of PTEN, CyclinD1 and CyclinA1+A2 proteins in three groups. Cell proliferation-toxicity test (CCK-8) was used to detect cell proliferation. Results The expression of miR-155 was significantly higher in H group than that in NC group and N group. The expression of target gene PTEN was lower in H group than that in NC group and N group (both P＜0.05). The expression of PTEN protein was significantly lower in H group than that in NC group and N group, while the expressions of CyclinD1 and CyclingA1+A2 protein were significantly higher in H group compared with that of NC group and N group (both P＜0.05). CCK-8 results showed that the photometric values of the three groups began to differ at 12 h, and the luminosity values were significantly greater in H group than those of NC group and N group from 24 h to 72 h, but the difference was not statistically significant between NC group and N group. Conclusion Overexpression of miR-155 can promote the proliferation of HepG2 cells.

Key words: liver neoplasms, hepatocytes, microRNAs, lentivirus infections, microRNA-155