the role of med19 in the proliferation and tumorigenesis of human hepatocellular carcinoma cells aim to explore the role of med19 a component of the mediator complex that coactivates dnabinding transcription factors in the proliferation and tumorigenesis of human hepatocellular carcinoma cellsmethods the human hepatocellular carcinoma cell lines hepg2 and hep3b were infected with lentiviral vectors encoding interfering rna rnai targeting the med19 gene to further confirm the inhibitory effects of rnai vectors on med19 gene expression quantitative realtime rtpcr and western blotting assays were used the proliferation of hepg2 and hep3b cells after transduction with the med19rnailentivirus vector was evaluated by mtt conversion brdu incorporation colony formation and cellcycle assays in vitro in addition the ability of the med19rnailentivirus vectorinfected hep3b cells to form tumors after inoculation into nude mice was determinedresults recombinant lentiviral vectors expressing small interfering rna sirna against med19 were constructed and were found to efficiently downregulate med19 mrna and protein levels in hepg2 and hep3b cells furthermore the inhibition of med19 by rnai dramatically reduced hepatocellular carcinoma cell proliferation induced cellcycle arrest in the g0g1 phase and suppressed tumor formationconclusion these results provide new evidence of an important role for med19 in the development of hepatocellular carcinomas suggesting that lentivirusmediated rnai to target med19 is a potential tool for inhibiting cancer cell proliferation and tumorigenesis