OBJECTIVETo explore the effect and mechanism of Poly I:C in inducing growth inhibition and apoptosis of human hepatocellular carcinoma SMMC-7721 cells.

METHODSSMMC-7721 cells were treated with different doses of Poly I:C for 24, 48, and 72 h, and the cell growth inhibition rate was analyzed with CCK-8 assay. The cell cycle and the apoptosis were analyzed using flow cytometry with Annexin-V and PI staining, and quantitative RT-PCR analysis were used to detect the expression of TLR3, TRIF, and IFN-beta mRNA in cells.

RESULTSIn the cells exposed to Poly I:C at low, moderate, and high doses, the inhibitory rates was the highest in high-dose Poly I:C group, and at a given Poly I:C dose, prolonged exposure resulted in significantly increased cell growth inhibition rate (P<0.05). Flow cytometry showed that Poly I:C induced cell apoptosis in a time- and dose-dependent manner and significantly increased the percentage of G1-phase cells as compared with that in the control group. The mRNA level of TLR3, TRIF, and IFN-beta were also increased following Poly I:C treatment in comparison with the control group.

CONCLUSIONPoly I:C can induce significant growth inhibition and apoptosis of SMMC-7721 cells in a dose- and time-dependent manner possibly by causing cell cycle arrest and TLR3 signaling pathway activation that leads to IFN-beta production and cell apoptosis.