Abstract: Objective To investigate the effcet of Stat5- shRNA on inhibition of human hepatocellular carcinoma (HCC) SMMC7721 xenograft and induction of tumor apoptosis in nude mice.Methods SMMC7721 cell suspension solution was inoculated subcutaneously into the flank of nude mice.Tumor was identified based on existence of nodules or hardened texture at the site of inoculation at day 15 and thereafter.A cohort of 15 tumor-loaded nude mice were then randomly divided into blank control(n=5),HK plasmid control (n=5) and Star5-shRNA group (n=5),respectively.The blank control group was intratumorally injected with normal salinc,HK plasmid control group with Pgenesil-l-HK,and Stat5-shRNA group with Pgenesil-1-Stat5A1,respectively,for 50 μl per mouse,once every other day with a total of 10 injections.At day 35,the mice were euthanized for hatvesting the tumors and computation of tmnor size and inhibition rate.While tumor apoptosis was examined via flow cytometry.Results Stat5-shRNA treatment resulted in markcd inhibition of tumor growth and mounted apoptosis rate (both P<0.05) on hmnan HCC xenograft in nude mice as compared with blank control and HK plasmid control group [ (21.35±3.69)% vs (3.56 ± 1.12)%,(3.81 ± 3.05)%,P<0.05].Conclusion Stat5 - shRNA is correlated with effective inhibition of human HCC xenograft and induction of tumor apoptosis in nude mice,suggesting the potential for gene therapy in patients with HCC.