Abstract: ObjectiveTo investigate the effect of microRNA99a5p （miR99a5p） on the invasion and migration of hepatoma cells HepG2 and its regulatory role on insulinlike growth factor 1 receptor （IGF1R）. 
MethodsNinety pairs of cancerous and paracancerous tissues surgically removed in our hospital were collected from January 2014 to March 2017. Realtime quantitative PCR （QPCR） was used to detect the level of miR99a5p and IGF1R mRNA in the above tissues. HepG2 cells were transfected with miR99a5p mimics （overexpression group） and miR99a5p negative control （NC group） by liposome method. QPCR method was used to detect the miR99a5p level of each group after transfection for 48 h to evaluate the transfection efficiency. The invasion and migration of each group were evaluated by Transwell and scratch test， respectively. The mRNA and protein levels of IGF1R were detected by QPCR and Western blotting， respectively. The dual luciferase reporter gene test was applied to verify the targeting effect of miR99a5p on IGF1R. 
ResultsThe results of QPCR showed that the level of miR99a5p in the cancer tissues was 0823±0039， lower than 1016±0013 in normal paracancerous tissues， while the level of IGF1R mRNA in the cancer tissues was 1329±0024， higher than 1035±0026 in normal paracancerous tissues （P＜005）. The miR99a5p level in the overexpression group was 1487±0027， higher than 1021±0013 of control group and 1019±0025 of NC group （P＜005）. The healing rates of control group， NC group and overexpression group were （605±24）％， （584±33）％ and （421±29）％， and the numbers of membrane cells were 921±37， 952±49 and 367±45， respectively. Compared with other two groups， the healing rates and numbers of membrane cells of overexpression group decreased （P＜005）. The mRNA and protein levels of IGF1R in overexpression group were lower than those in other two groups （P＜005）. The results of double fluorescence report showed that miR99a5p significantly inhibited the luciferase activity of cells transfected with the wild type IGF1R3’UTR plasmid （P＜001）， but had no significant effect on the activity of the mutant IGF1R3’UTR luciferase activity. 
ConclusionThe expression of miR99a5p is reduced in hepatoma cancer. MiR99a5p can inhibit the invasion and migration of hepatoma cells. It may be realized by targeting IGF1R， which can be used as a potential target for the treatment of hepatoma cancer.

Key words: Hepatoma cancer, MicroRNA99a5p, Invasion, Migration, Insulinlike growth factor 1 receptor