Abstract: Objective To investigate the effect of cytokine-induced apoptosis inhibitor 1 （CIAPIN1） gene on the proliferation of HepG2 cells and the mechanism involved. Method Recombinant lentiviral CIAPIN1 expression vector and CIAPIN1 silencing vector were constructed and used to infect HepG2 cells in vitro to obtain cells with stable high and low expression of CIAPIN1 gene. The experiment included four groups,e.g. CIAPIN1 overexpression,CIAPIN1 low expression,unrelated silent RNA（siRNA） interference,and blank control group. The CIAPIN1 mRNA and its protein,cell proliferation,cyclinD1,CDK4,cyclin E,CDK2,IKKβ,phosphorylated IKBα,p65 and phosphorylated p65 in each group were detected by RT-PCR, FCM and Western bloting. Results The proliferation of CIAPIN1 in low expression group was significantly inhibited,with the cell ratio of G0/G1 was much higher than that in CIAPIN1 high expression group [（73.2±2.5）% vs. （58.8 ±2.2）%,in siRNA interference group （62.4±1.8）%,or in the control group （63.2±2.6）%,P<0.05];the expression of cyclinD1,CDK4,cyclin E,CDK2 in CIAPIN1 overexpression group were much higher than those in other groups（P<0.05）;the relative expression of phosphorylated IKBα and phosphorylated p65 in CIAPIN1 overexpression group were （1.335±0.182） and（0.731±0.106）,respectively,both significantly higher than those in GIAPIN1 low expression group [（0.108±0.035） and （0.028±0.010）],in siRNA interference group [（0.251±0.082） and （0.318±0.058）],as well as in control group[（0.238±0.067） and（0.322±0.061）,P<0.05]. Conclusion CIAPIN1 can promote the proliferation of HepG2 cells, which may be related to the activation of NF-кB signaling pathway.

Key words: HepG2 cells, Cytokine-induced apoptosis inhibitor 1, Cell proliferation, Cell cycle, NF-кB signaling pathway