Transfection and expression of hepatitis B virus x gene and its effect on apoptosis in HL-7702 cells

AIM: To investigate the effects of hepatitis B virus x gene and its protein product HBxAg on apoptosis in hepatocyte line HL-7702. METHODS: The reconstituted plasmid pcDNA3-x was established through recombination DNA technique; pcDNA3X was transfected into HL-7702 cells by lipid-mediated trasfection. Positive clones were screened by G418, and HL7702/HI3x cells were analysed by the RT-PCR to confirm the steady expression of X gene in HL-7702 cells. The apoptosis rate in HL-7702 cells was determined by flow cytometry, TUNEL technology, electronic microscope. At the mean time, pcDNA3-X was transfected transiently into HL-7702 cells, and total RNA from HL-7702 cells was extracted 24, 48, 72, 96 and 120 h after the transient transfection, and semiquantitative analysis was performed by RT-PCR to detect the expression of HI3V X gene. Furthermore, apoptosis rate in HL-7702 cells was determined by flow cytometry analysis at the different times. RESULTS: RT-PCR analysis showed that HI3V X gene could be expressed stably in HL-7702 cells. Both flow cytometry and TUNEL technology revealed that the apoptosis rates of HL-7702/HI3x cells were much higher than those of HL-7702/ pcDNA3 and HL-7702 cells. Furthermore, the apoptotic phenomena and apoptotic body were observed in HL-7702/ HI3x cells under electronic microscope, but not in HL-7702/ pcDNA3 and HL-7702 cells. In the experiment of transient transfection, RT-PCR reveals that X gene was expressed most at 72 h after transfection; and the apoptosis rate reached the highest at the same time. After that, the apoptosis rate was reduced with the decrease of the X gene expression. CONCLUSION: HBV X gene and X protein can promote the apoptosis in hepatocyte. And there exist a quantity-effect relationship between the X gene expression and apoptosis rate in hepatocyte.

Construction of IL-2 gene-modified human hepatocyte and its cultivation with microcarrier

AIM: To construct interleukin-2 gene-modified humanhepatocyte line (L-02/IL-2) and investigate the changes ofthe function of liver cells and IL-2 secretion in culture withmicrocarrier, laying the foundation for further experimentationon hepatocyte transplantation.METHODS: hIL-2 gene was transduced into L-02hepatocytes by recombinant retroviral vector pLNCIL-2, andthe changes of morphology and clonogeneicity rate of thetransduced cells were observed, the secretion levels of hIL-2 in cultural supernatant were detected by ELISA and NeoRgene was amplified by PCR. The growth of L-02/IL-2, thespecial biochemistry items and the levels of IL-2 weredetected after cultivation with microcarrier.RESULTS: The clonogeneicity rate of the L-02/IL-2 cellswas lower than that of L-02/Neo cells and L-02 cells. Thelevels of hIL-2 could reach 32 000 pg/106 cells per day andkept secreting for more than ten weeks. NeoR gene segmentwas respectively obtained by PCR from both L-02/IL-2 andL-02/Neo cell's genomic DNA. At the 6th day in culture withmicrocarrier, the matrix-induced liver cell aggregates wereformed, the number of alive L-02/IL-2 cell were 16.8±0.53x106/flask and the levels of ALB and UREA were 52.54±1.28mg/L and 5.29±0.17 mmol/L, respectively. These data hadnot significantly changed as compared with those of L-02cells (P＞0.05); However, the levels of IL-2 in IL-2/L-02 cellsremarkably exceeded that in L-02 cells in the whole cultureprocess (P＜0.001).CONCLUSION: The IL-2 gene-modified hepatooyte line hasbeen successfully constructed. The L-02/IL-2 cellularaggregates cultured with microcarrier have a high capacityof IL-2 production as well as protein synthesis and aminoacid metabolism.

Cooperative inhibitory effects of antisense oligonucleotide of cell adhesion molecules and cimetidine on cancer cell adhesion

AIM: To explore the cooperative effects of antisense oligonucleotide (ASON) of cell adhesion molecules and cimetidine on the expression of E-selectin and ICAM-1 in endothelial cells and their adhesion to tumor cells. METHODS: After treatment of endothelial cells with ASON and/or cimetidine and induction with TNF-α, the protein and mRNA changes of E-selectin and ICAM-1 in endothelial cells were examined by flow cytometry and RT-PCR,respectively. The adhesion rates of endothelial cells to tumor cells were measured by cell adhesion experiment. RESULTS: In comparison with TNF-α inducing group, lipoASON and lipo-ASON/cimetidine could significantly decrease the protein and mRNA levels of E-selectin and ICAM-1 in endothelial cells, and lipo-ASON/cimetidine had most significant inhibitory effect on E-selectin expression (from 36.37±1.56% to 14.23±1.07%, P<0.001). Meanwhile,cimetidine alone could inhibit the expression of E-selectin(36.37±1.56% vs 27.2±1.31%, P<0.001), but not ICAM-1(69.34±2.50% vs68.07±2.10%,P>0.05)and the two kinds ofmRNA, either. Compared with TNF-α inducing group, the rate of adhesion was markedly decreased in lipo-E-selectin ASON and lipo-E-selectin ASON/cimetidine treated groups(P<0.05),and lipo-E-selectin ASON/cimetidine worked better than lipo-E-selectin ASON alone except for HepG2/ECV304 group(P<0.05). However, the decrease of adhesion was not significant in lipo-ICAM-1 ASON and lipo-ICAM-1 ASON/dmetidine treated groups except for HepG2/ECV304 group (P >0.05). CONCLUSION: These data demonstrate that ASON in combination with cimetidine in vitro can significantly reduce the adhesion between endc^thelial cells and hepatic or colorectal cancer cells, which is stronger than ASON or cimetidine alone. This study provides some useful proofs for gene therapy of antiadhesion.