Effects of interleukin-2 transduction on the human hepatoma cell lines using retroviral vector

Prevention of hepatocellular carcinoma in mice by IL-2 and B7-1 genes co-transfected liver cancer cell vaccines

AIM: To study the immunoprotective effect of liver cancer vaccine with co-transfected IL-2 and B7-1 genes on hepatocarcinogenesis in mice.

METHODS: The murine liver cancer cell line Hepal-6 was transfected with IL-2 and/or B7-1 gene via recombinant adenoviral vectors and the liver cancer vaccines were prepared. C57BL/6 mice were immunized with these vaccines and challenged with the parental Hepal-6 cells afterwards. The immunoprotection was investigated and the reactive T cell line was assayed.

RESULTS: The immunoprotection of the tumor vaccine was demonstrated. The effect of IL-2 and B7-1 genes co-transfected Hepal-6 liver cancer vaccine (Hep6-IL2/B7 vaccine) on the onset of tumor formation was the strongest. When attacked with wild Hepal-6 cells, the median survival period of the mice immunized with Hep6-IL2/B7 vaccine was the longest (68 d, χ² = 7.70-11.69, P < 0.05) and the implanted tumor was the smallest (z = 3.20-44.10, P < 0.05). The effect of single IL-2 or B7-1 gene-transfected vaccine was next to the IL2/B7 gene co-transfected group, and the mean survival periods were 59 and 54 d, respectively. The mean survival periods of wild or enhanced green fluorescence protein gene modified vaccine immunized group were 51 and 48 d, respectively. The mice in control group all died within 38 d and the implanted tumor was the largest (z = 3.20-40.21, P < 0.05). The cellular immunofunction test and cytotoxicity study showed that the natural killer (NK) cell, lymphokine activated killer (LAK) cell and cytotoxic T lymphocyte (CTL) activities were significantly increased in mice immunized with the Hep6-IL2/B7 vaccine, (29.5% ± 2.5%, 65.0% ± 2.9%, 83.1% ± 1.5% respectively, compared with other groups, P < 0.05).

CONCLUSION: The Hep6-IL2/B7 liver cancer vaccines can induce the mice to produce activated and specific CTL against the parental tumor cells, and demonstrate stronger effect on the hepatocarcinogenesis than single gene modified or the regular tumor vaccine. Therefore, the vaccines may become a novel potential therapy for recurrence and metastasis of HCC.

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

AIM: To construct interleukin-2 gene-modified human hepatocyte line (L-02/IL-2) and investigate the changes of the function of liver cells and IL-2 secretion in culture with microcarrier, laying the foundation for further experimentation on hepatocyte transplantation.

METHODS: hIL-2 gene was transduced into L-02 hepatocytes by recombinant retroviral vector pLNCIL-2, and the changes of morphology and clonogeneicity rate of the transduced cells were observed, the secretion levels of hIL-2 in cultural supernatant were detected by ELISA and NeoR gene was amplified by PCR. The growth of L-02/IL-2, the special biochemistry items and the levels of IL-2 were detected after cultivation with microcarrier.

RESULTS: The clonogeneicity rate of the L-02/IL-2 cells was lower than that of L-02/Neo cells and L-02 cells. The levels of hIL-2 could reach 32000 pg/10⁶ cells per day and kept secreting for more than ten weeks. NeoR gene segment was respectively obtained by PCR from both L-02/IL-2 and L-02/Neo cell’s genomic DNA. At the 6^th day in culture with microcarrier, the matrix-induced liver cell aggregates were formed, the number of alive L-02/IL-2 cell were 16.8 ± 0.53 × 10⁶/flask and the levels of ALB and UREA were 52.54 ± 1.28 mg/L and 5.29 ± 0.17 mmol/L, respectively. These data had not significantly changed as compared with those of L-02 cells (P > 0.05); However, the levels of IL-2 in IL-2/L-02 cells remarkably exceeded that in L-02 cells in the whole culture process (P < 0.001).

CONCLUSION: The IL-2 gene-modified hepatocyte line has been successfully constructed. The L-02/IL-2 cellular aggregates cultured with microcarrier have a high capacity of IL-2 production as well as protein synthesis and amino acid metabolism.