The payload of mouse interferon-γ gene enhances the antitumor activity of the oncolytic adenovirus CNHK300 in hepatocellular carcinoma

Abstract

Objective To study the effect of mouse interferon-γ （mlFN-γ） insertion on the selective replication and cytotoxicity of a tumor-specific oncolytic adenovirus CNHK300 in hepatocellular carcinoma （HCC） cells and HCC xenografts. Methods The eytotoxicity of CNHK300-mlFN-γ （CNHK300- Mγ） was examined by methyl thiazol tetrazolium （MTT） calorimetric assay in normal and HCC ceils. Healthy nude BALB/C mice were injected with the SMMC-7221 cells. Forty mice with tumors of 5-8 mm in diameter were randomly divided into 4 groups of 10 mice ： CNHK300-Mγ/group （ CNHK300-Mγ was injected into the tumor once every other day for 5 times）, CNHK300 group （CNHK300 was injected） , ONYX- 015 group （ONYX-015 was injected）, and control group （diluent of virus was injected）. Seven, 14, 21, 28, 35, and 42 days after the initial injection the size of tumor was examined （ Tumor volume was estimated as a × b2 ×0. 5, where a and b were the maximal and minimal diameters, respectively）. Forty-eighth after the finish of the whole course of treatment, the mice were killed. Twenty-four mice with the same tumors were randomly divided into 3 groups of 8 mice ： CNHK300-Mr group, CHNK300 group and control group. The mice were killed in half, 3, 7 days after the last injection. Enzyme linked immunosorbent assay （ELISA） was used to detect the expression of mlFN-γ/in blood. Results CNHK300-M-γ could selectively kill tumor cell lines, whose 50% inhibitory concentration （ IC50 ） was under 1 in tumor cells and 370 in normal liver cells. ELISA showed that the expression of mlFN-γ in the blood of the CNHK300-Mγ group was （231 ± 101 ） ng/L or （ 1733 ± 191 ） ng/L in 3 days or 7 days after virus infection, while no mlFN-γ could be detected in CHNK300 group and control group. The tumor size in the CNHK300-Mr group was significantly smaller than in the CNHK300 group, ONYX-O15 group, and control group （P 〈 0. 05 ）. Conclusion Being capable of specifically killed HCC ceils and mediating effective expression of therapeutic gene in vivo, CNHK3OO-Mγ holds a splendid future as a potential antitumor agent. Key words: Carcinoma,hepatocelhdar; Adenovirus; Telomerase; Gene therapy; Interferon-γ