NT4(Si)-p53(N15)-antennapedia induces cell death in a human hepatocellular carcinoma cell line

AIM： To construct the recombinant lentivirus expression plasmid, pLenti6/V5-NT4 p53（N 15）-antennapedia （Ant）, and study its effect on HepG2 cells. METHODS： Plasmid pLenti6/V5-NT4 p53（N15）-Ant was constructed incorporating the following functional regions, including signal peptide sequence and proregion of neurotrophin 4, N-terminal residues 12-26 of p53 and 17 amino acid drosophila carrier protein, Ant. Hepatocellular carcinoma （HepG2） cells were used for transfection. 3-[4,5-climethyl-thiazol-2yl]-2,5 diphenyl tetrazolium bromide （MI-I） assay, lactate dehydrogenase （LDH） release assay, transmission electron microscopy （TEM） and flow cytometric analysis （FCM） were employed to investigate the effects of LV-NT4（Si）- p53（N15）-Ant in vitro on HepG2 cells. In vivo experiment was also performed to investigate the inhibitory effect of LV-NT4（Si）-p53（N15）-Ant on tumor growth in nude mice.RESULTS： LV-NT4（Si）-p53（N15）-Ant significantly suppressed the growth of HepG2 cells. MTT assay showed that the growth of HepG2 cells was mucj more significantly inhibited by LV-NT4（Si）-p53（N15）-Ant than by LV-EGFP. The inhibition rate for HepG2 cell growth in the two groups was 46.9% and 94.5%, respectively, 48 h after infection with LV-NT4（Si）-p53（N15）-Ant, and was 33.9% and 95.8%, respectively, 72 h after infection with LV-NT4（Si）-p53（N15）-Ant （P 〈 0.01）. Light microscopy and TEM showed morphological changes in HepG2 cells infected with LV-NT4（Si）-p53（N15）-Ant, but no significant changes in HepG2 cells infected with LV-EGFR Changes were observed in ultra-structure of HepG2 cells infected with LV-NT4（Si）-p53（N15）-Ant, with degraded membranes, resulting in necrosis. LDH release from HepG2 cells was analyzed at 24, 48, 72 and 96 h after infection with LV-NT4（Si）-p53（N15）-Ant and LV-EGFP, which showed that LDH release was significantly higher in LV-NT4（Si）-p53（N15）-Ant treatment group （682 IU/L） than in control group （45 IU/L, P 〈 0.01）. The longer the time was after infection, the bigger the difference was in LDH release. FCM analysis showed that LV-NT4（Si）- p53（N15）-Ant could induce two different kinds of cell death： necrosis and apoptosis, with apoptosis being the minor type and necrosis being the main type, suggesting that LV-NT4（Si）-p53（N15）-Ant exerts its anticancer effect on HepG2 cells by inducing necrosis. The in vivo study showed that LV-NT4（Si）-p53（N15）-Ant significantly inhibited tumor growth with an inhibition rate of 66.14% in terms of tumor size and weight. CONCLUSION： LV-NT4（Si）-p53（N15）-Ant is a novel recombinant lentivirus expression plasmid and can be used in gene therapy for cancer.