Abstract: Objective To probe the effects of HBX protein trans-activate gene XTP4 on cell apoptosis of HepG2 cells. Methods The plasmid pcDNA3.1/myc-His (－)A-XTP4 (pXTP4) was constructed, XTP4 gene interference RNA（siRNA) was synthesized Chemically. And then negative control(NC、siNC) were transiently transfected into HepG2 cells respectively.The following experment were carried out post 48 hours.Western blot was used to make sure the overexpression and interference expression of XTP4 protein .Flow cytometry was used to observe cell apoptosis .While Bcl-2、Bax protein were semiquantified by western blot,and then the ratio of Bcl-2 to Bax was caculated. The activities of caspase-3 were detected by caspase-glo 3/7 luminometer respectively. Results The plasmid pXTP4 was successfully constructed,XTP4 protein overexpressed and interferenced . Compared with control group respectively, the number of Annexin V-positive cells was decreased （P＜0.05）, the ratio of Bcl-2 to Bax upregulated （P＜0.05) ,the activity of caspase-3 was reduced in pXTP4（P＜0.05）.While the number of Annexin V-positive cells was increased （P＜0.05）,the ratio of Bcl-2 to Bax downregulated （P＜0.05）, the activity of caspase-3 was increased in siXTP4（P＜0.05）. Conclusion The apoptosis of HepG2 was suppressed by XTP4,and the possible mechanism may be through the upregulate of Bcl-2/Bax.

Key words: Key words：XTP4 gene, HepG2 cells, apoptosis