Effects Of The Proliferation And Apoptosis Of Hepatocellular Carcinoma Cell Line HepG2 By Transfecting MicroRNA-122 Mimics

Background: Primary hepatic carcinoma (PHC) is one of the most common malignancies worldwide. MiR-122 (microRNA-122) is a single chain small molecule RNA that does not code for proteins presented in eukaryotes. Recent studies have shown that miR-122 inhibited hepatocellular carcinoma cell's proliferation and stimulated hepatocellular carcinoma cell apoptosis. Objective:To observe the effects of the apoptosis of hepatocellular carcinoma cell line HepG2 by microRNA-122 and explore the possible mechanism. To provide the experiment evidences for the novel treatment approaches of PHC. Methods:The experiment were devide into four groups by different treatments:that was MiR-122 mimics group, Negative Control siRNA group, Transfection reagen group and Blank control group. The HepG2 cells apotosis after transfected Allstars Hs Cell Death Control siRNA (lethal control siRNA) were observed to estimate the rate of cell transfection according to the reagents specification description. Use the method of MTT (thiazolyl blue) to measure the proliferation inhibition rates of the four groups cells after incubated 24h, 48h and 72h respectively. Flow cytometry was used to detect the apotosis rate of the four groups cells after cultured 24h and then tinted by Annexin V. Semi-quantitative RT-PCR analysis was used to detect the mRNA expression level of Bax,Bcl-2,caspase-9,caspase-3 in the four groups cells after incubated 24h respectively. Cell Immunohistochemistry was used to detect the protein expression level of Bcl-w, Bax, caspase-9, caspase-3 in the four groups cells after cultured 24h respectively.Results: Under the General microscope we observed the cells'transfection efficiency was 80%. (1) MTT assay showed that: the MiR-122 mimic group 24h growth inhibition rate are significantly higher than Negative control group, Transfection reagent group and Blank control group (P<0.01). (2) Flow cytometry results showed that: the apoptosis rate of MiR-122 mimic group is significantly increased. There are all have significant differences campared to Negative control, Transfection reagent group and Bank control group, all have significant differences (P <0.01). The 24h growth inhibition rate of the MiR-122 mimic group is higher than 48h and 72h. (3) RT-PCR results showed that: Campared with Negative control, Transfection reagent group and Blank control group, the MiR-122 mimic group's Bcl-w mRNA expression is significantly reduced (P<0.01), The mRNA level of caspase-9, caspase-3 mRNA expression are dramatically increased (P<0.01). But there are no significant changes in the Bax mRNA (P>0.05). (4)Cell Immunohistochemistry results showed that: Campared with these control group, the MiR-122 mimic group's Bcl-w protein expression is significantly reduced (P<0.01), and the caspase-9, caspase- 3 protein expression are significantly increased (P<0.01), But the Bax protein expression has no significant changes.(P>0.05)Conclusions: HepG2 cells that transfected with miR-122 mimics is inhibited proliferation and stimulated apoptosis. Then shows MiR-122 can inhibit hepatocellular carcinoma cells'proliferation and promote apoptosis maybe through the intrinsic apoptotic pathway.