Objective To investigate the clinical significance of the expression of antioxidant 1 copper chaperone protein(ATOX1)in hepatocellular carcinoma(HCC)and its relationship with tumor proliferation,migration and invasion.Methods The expression of ATOX1 mRNA in HCC cancer tissue and normal liver tissue was analyzed using the Human Genome Atlas database.Immunohistochemical experiment was used to detect the expression of ATOX1 in 15 cases of HCC cancer tissue and adjacent tissue.Human HCC cell lines Hep3B and HepG2 were divided into the control group(NC),the ATOX1 knockdown group 1(si-ATOX1#1)and the ATOX1 knockdown group 2(si-ATOX1#2).The effects of ATOX1 knockdown on the malignant biological behavior of HCC cells were observed through CCK-8 cell proliferation experiment,scratch experiment and Transwell invasion experiments.A nude mouse xenograft tumor model was constructed to analyze the effect of ATOX1 knockdown on the quality and volume of transplanted tumors.Western blot assay was used to detect the relationship between ATOX1 and JAK2/STAT3 pathway protein expression.Results Bioinformatics analysis showed that expression of ATOX1 mRNA in HCC cancer tissue was higher than that in adjacent normal tissue(P＜0.05).The immunohistochemical staining results showed that the positive rate of ATOX1 protein was higher in HCC cancer tissue than that in adjacent tissue(93.33%vs.13.33%,P＜0.01).In vitro experimental results showed that siRNA knockdown of ATOX1 protein expression in Hep3B and HepG2 cells significantly reduced the proliferation,migration and invasion abilities of cancer cells(P＜0.05).In vivo experiments in mice showed that the volume and weight of subcutaneous xenograft tumors were significantly smaller in the sh-ATOX1 group than those in the sh-con group(P＜0.05).The expression levels of JAK2/STAT3 pathway-related proteins p-JAK2,p-STAT3,CyclinD1 and MMP2 were significantly lower in the subcutaneous transplanted tumor tissue of the sh-ATOX1 group than that of the sh-con group(P＜0.05).Conclusion ATOX1 can promote the proliferation,migration and invasion of HCC through JAK2/STAT3 pathway,which can potentially become a potential tumor marker and therapeutic target.