BACKGROUND:Melanoma differentiation associated gene-7(mda-7)is a novel tumor suppressor gene,which has suppressor activity in a broad spectrum of human cancer cells both in vitro and in vivo through activation of various intracellular signaling pathways.In this study, we investigated the potential effect of mda-7 on human hepatocellular carcinoma(HCC)in vitro. METHODS:Cells from the human HCC cell line Hep3B and the human liver cell line L-02 were assigned to three groups. One was cultured in Dulbecco’s modified Eagle’s medium without serum(control).The others were transfected with adenovirus expressing the mda-7 gene(Ad.mda-7)or adenovirus vector serving as negative control(Ad.vec).The expression of MDA-7 and Bcl-2 proteins in Hep3B and L-02 cells was confirmed by the reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay. The methyl thiazolyl tetrazolium colorimetric assay and flow cytometry were used to assess tumor cell proliferation and the cell cycle.Hoechst and Annexin-V/propidium iodide staining were used to study mda-7 gene expression in Hep3B and L-02 cells.The expression of MDA-7,Bcl-2 and Bax proteins were detected by Western blotting.RESULTS:The mda-7 gene was expressed in Hep3B and L-02 cells.The protein concentrations of MDA-7 in supernatants were 790 and 810 pg/ml,respectively.mda-7 induced Hep3B growth suppression and apoptosis,compared with Ad.mda-7 and control(P<0.01).In addition,cell block in G2/M was identified by exposure of HCC cells to secreted MDA-7 protein,but this was not found in L-02.The gene expression of Bcl-2 was markedly decreased in Hep3B but not in L-02. CONCLUSIONS:mda-7 selectively induces growth inhibi- tion and apoptosis in the HCC cell line Hep3B but not in the normal liver cell line L-02 via downregulating the anti- apoptosis protein Bcl-2.It could be an ideal gene for gene therapy in HCC. BACKGROUND: Melanoma differentiation associated gene-7 (mda-7) is a novel tumor suppressor gene, which has suppressor activity in a broad spectrum of human cancer cells both in vitro and in vivo through activation of various intracellular signaling pathways. In this study, METHODS: Cells from the human HCC cell line Hep3B and the human liver cell line L-02 were assigned to three groups. One was cultured in Dulbecco’s modified The others were transfected with adenovirus expressing the mda-7 gene (Ad.mda-7) or adenovirus vector serving as negative control (Ad.vec). The expression of MDA-7 and Bcl-2 proteins in Hep3B and L-02 cells was confirmed by the reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay. The methyl thiazolyl tetrazolium colorimetric assay and flow cytometry were used to assess tumor cell proliferation and the cell cycl E. Hoechst and Annexin-V / propidium iodide staining were used to study mda-7 gene expression in Hep3B and L-02 cells. The expression of MDA-7, Bcl-2 and Bax proteins were detected by Western blotting. mda-7 gene was expressed in Hep3B and L-02 cells. The protein concentrations of MDA-7 in supernatants were 790 and 810 pg / ml, respectively. mda-7 induced Hep3B growth suppression and apoptosis, compared with Ad.mda-7 and control (P <0.01) .In addition, cell block in G2 / M was identified by exposure of HCC cells to secreted MDA-7 protein, but this was not found in L-02. The gene expression of Bcl-2 was markedly decreased in Hep3B but not in L-02. CONCLUSIONS: mda-7 selective induces growth inhibition and apoptosis in the HCC cell line Hep3B but not in the normal liver cell line L-02 via downregulating the anti- apoptosis protein Bcl-2 .It could be an ideal gene for gene therapy in HCC.