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Among numerous gene therapeutic strategies for cancer treatment, gene transfer by conditionally replicative adenovirus (CRAd) of interferon-gamma (IFN-gamma) may be useful because of the possibility that it will yield IFN-gamma-mediated antiangiogenesis, immune responses, and CRAd-mediated oncolysis. In this study, we constructed a human TERT promoter-mediated oncolytic adenovirus targeting telomerase-positive cancers and armed with a mouse or human IFN-gamma gene to generate novel immune gene-viral therapeutic systems, CNHK300-mIFN-gamma and CNHK300-hIFN-gamma, respectively. The systems can specifically target, replicate in, and lyse cancer cells, while sparing normal cells. The advantage of these systems is that the number of transgene copies and their expression increase markedly via viral replication within infected cancer cells, and replicated viral progeny can then infect additional cancer cells within the tumor mass. CNHK300-mIFN-gamma induced regression of xenografts in liver cancer models in both immunodeficient and immunocompetent mice by triplex mechanisms including selective oncolysis, antiangiogenesis, and immune responses. We conclude that combining immune gene therapy and oncolytic virotherapy can enhance antitumor efficacy as a result of synergism between CRAd oncolysis and transgene composite antitumor responses.

Data from clinical trails have shown that the antitumoral effect of ONYX-015, an E1B 55kDa-deficient adenovirus, as monotherapy is insufficient. To enhance its efficiency, CNHK200-mE, another E1B 55kDa-deficient adenovirus armed with a mouse endostatin gene was constructed and its antitumoral activities against hepatocellular carcinoma (HCC) in vitro and in vivo were investigated. The selective replication and cytotoxicity of CNHK200-mE in Hep3B and HepGII cells independent of p53 status were confirmed via TCID50 and 3-(4,5dimetylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assays. Potent tumor growth suppression on SMMC-7721 xenografts in nude mice was observed and a synergistic effect of the carrier virus and the therapeutic gene was suggested. Moreover, in comparison with the nonreplicative adenovirus carrying the same therapeutic gene, amplified transgene expression of mouse endostatin in vitro and in vivo were confirmed by Western blotting and ELISA assay. The effective angiogenesis inhibition and replication of CNHK200-mE in nude mice xenografts were demonstrated by immunohistochemistry. In conclusion, the recombinant adenovirus CNHK200-mE is a replication-competent oncolytic virus mediating high expression of therapeutic gene. Because CNHK200-mE is capable of replicating in and lysing HCC cells selectively with effective tumor growth suppression and antiangiogenic activity on HCC xenografts in nude mice, it holds good potential for the treatment of HCC.

Gene-viral therapy, which uses replication-selective transgene-expressing viruses to manage tumors, can exploit the virtues of gene therapy and virotherapy and overcome the limitations of conventional gene therapy. Using a human telomerase reverse transcriptase-targeted replicative adenovirus as an antiangiogenic gene transfer vector to target new angiogenesis and making use of its unrestrained proliferation are completely new concepts in tumor management. CNHK300-mE is a selective replication transgene-expressing adenovirus constructed to carry mouse endostatin gene therapeutically. Infection with CNHK300-mE was associated with selective replication of the adenovirus and production of mouse endostatin in telomerase-positive cancer cells. Endostatin secreted from a human gastric cell line, SGC-7901, infected with CNHK300-mE was significantly higher than that infected with nonreplicative adenovirus Ad-mE in vitro (800 ± 94.7 ng/ml versus 132.9 ± 9.9 ng/ml) and in vivo (610 ± 42 ng/ml versus 126 ± 13 ng/ml). Embryonic chorioallantoic membrane assay showed that the mouse endostatin secreted by CNHK300-mE inhibited angiogenesis efficiently and also induced distortion of pre-existing vasculature. CNHK300-mE exhibited a superior suppression of xenografts in nude mice compared with CNHK300 and Ad-mE. In summary, we provided a more efficient gene-viral therapy strategy by combining oncolysis with antiangiogenesis.

To study the injection of NKG5SV gene to inhibit growth and metastasis of hepatocellular carcinoma (HCC).NKG5SV gene was inserted into retroviral vector pLXSN by normal methods. LacZ gene was used as control. LCI-D20 tumor together with saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was subcutaneously inoculated to the nude mice. Tumor formation rate and tumor size were noted 35 days after inoculation. LCI-D20 tumor was inoculated subcutaneously. Saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was intratumorally injected respectively 10 days after inoculation. Tumor growth was observed 35 days after inoculation. Liver cancer was resected 22 days after intrahepatic inoculation. Saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was respectively injected at incisal margin or intraspleen. Mice were killed 35 days after inoculation to observe tumor recurrence at incisal margin, intrahepatic metastasis and extrahepatic metastasis.Tumor formation rate and tumor diameter(cm) were 1.76 +/- 0.11, 1.51 +/- 0.34, 0.33 +/- 0.04 in the control group, LacZ group, NKG5SV group respectively when tumor and different cDNA were inoculated together. Tumor diameter(cm) and weight(g) were 0.87 +/- 0.08, 0.83 +/- 0.05, 0.26 +/- 0.04; 0.43 +/- 0.06, 0.38 +/- 0.04, 0.08 +/- 0.06 in the control group, LacZ group, NKG5SV group respectively when different cDNA were injected into the LCI-D20 tumor. Sites with extrahepatic metastasis nidi, incisal margin recurrence tumor size(cm), intrahepatic metastasis nidi, metastasis involved hepatic lobes in the control group, LacZ group, NKG5SV group were 4.25 +/- 1.48, 4.25 +/- 1.04, 0.63 +/- 0.51; 1.51 +/- 0.27, 1.35 +/- 0.17, 0.81 +/- 0.17; 2.50 +/- 1.41, 2.38 +/- 1.06, 1.25 +/- 0.71; 2.13 +/- 0.99, 2.00 +/- 0.75, 1.38 +/- 0.74 respectively when NK cells were injected at incise margin. They were 4.38 +/- 1.85, 4.25 +/- 1.48, 1.00 +/- 0.75; 1.13 +/- 0.23, 0.97 +/- 0.29, 0.76 +/- 0.16; 2.50 +/- 1.41, 2.05 +/- 1.12, 0; 2.13 +/- 0.83, 1.75 +/- 0.88, 0 respectively when NK cell were injected intrasplenicly.NKG5SV gene can inhibit HCC growth and postoperative metastasis and recurrence.

To develop a new kind of vector system, named as gene-viral vector, which combines the advantages of the gene therapy and virus therapy.An anti-tumor gene was inserted into the genome of the replicative virus specific for the tumor cells by virus recombination technology. The killing effect, report gene expression of the green fluorescence protein, expression of the anti-tumor gene of mouse IL12, and the replication of the virus were observed respectively by cell pathology, fluorescence microscopy, ELISA and electron microscopy.A new kind of gene-viral vector system, in which the E1b-55 000 gene is deleted but the E1a gene of adenovirus is preserved, was constructed. The vector system possessed the same characteristics as the replicative virus ONYX-015, replication and proliferation in the tumor cells but not in the normal cells, thus specifically killing the tumor cells. Besides, it carried many kinds of anti-tumor genes. When carrying the report gene of the green fluorescence protein it made the expression of this gene in tumor cells far more effectively than the adenovirus vector employed in the traditional gene therapy did. However in the normal cells the expression of green fluorescence protein caused by this vector system was as little as or even less than that by the traditional adenovirus system. The similar result was also observed in the experiments of this vector system carrying the anti-tumor gene, gene of mouse IL12. The replication and proliferation of the virus carrying the gene of mouse IL12 in the tumor cells were confirmed by electron microscopy.Gene-viral vector is a new kind of vector in which the anti-tumor gene is inserted into the genome of the replicative virus specific for the tumor cells. It increases the expression of the anti-tumor gene by hundreds even tens of thousand times. It posseses all the advantages of gene therapy and virus therapy, thus further enhancing the curative effect and it overcomes such disadvantages as low transfer rate, low expression, lack of target tropism and low anti-tumor activity. It will become one of the most promising means in tumor treatment.