Antitumoral Effects Of The Oncolytic Adenovirus Expressing Hemagglutinin-Neuraminidase Of Newcastle Disease Virus

In recent years, treatment technology has made great strides, but the malignant tumor is a worldwide problem. Adenovirus vector-based gene therapy progress rapidly, and a large number of pre-clinical and clinical studies have been carried out, which the CRCA been a widespread concern. CRCA with tumor-specific replication functions, such oncolytic adenovirus can also spread to the adjacent tumor cells. In addition, studies have shown that the CRCA’s application also can stimulate the body to produce anti-tumor immune response, which play a supporting role for radiotherapy and chemotherapy. More importantly, with the appropriate tumor suppressor gene, CRCA can treat both primary and metastatic tumors.The tumor treatment success depends not only on the removal of the tumor cells validity, specificity is also one of the key indicators. Attention of social and economic benefits of NDV-based vaccines have been made in the livestock and poultry industry and the veterinary field, In addition, the virus also has anti-tumor effect. Cassel as early as in the1860s found that the tumor suppressor role of NDV in the experimental treatment of malignant melanoma in the clinical application of NDV73T. HN protein is one of the main structural proteins of NDV, which connections virus with the envelope through hydrophobic N-terminal. The HN protein has both hemagglutinin activity and neuraminidase activity similar to the influenza virus, and has the function of regulating viral infection and replication by interacting with the surface of the NAcneu of target cells. Different with influenza virus, the HN NA and HA present on the same functional configuration domain. Therefore, HN glycoprotein is not only can be mediated receptor recognition, but cleavage receptor, such NAcneu, by the NA activity. Previous studies showed that, as the anti-tumor immune adjuvant, HN protein has the function of the activation of DC, monocytes, NK, and T cells by IL-12receptor β chain. In addition, HN can stimulate DC of PBMC to produce large amounts of IFN-alpha (its secretion may be more than1000times higher than that of other blood cells). In the synergistic effect of IL-12and IFN-a, HN able to activate T cells and induce the delayed-type immune response, as well as CTL and Thl-type cellular immune response. HN induced IFN-a is also capable of upregulating the series with the antigen of cell adhesion and cell function related functions factor.Currently,27%of the human gene therapy research application adenovirus vector. The most common is a first generation adenovirus vector, such vector is a replication-defective in the E1gene deletion type vector. El gene participate in viral gene expression and host cell proteins and viral replication protein regulation. After the first generation adenovirus vector, there are the new adenovirus vectors (E1and E3deletion, E2deletion, E4deletion, E2and E4deletions, E1/E2/E4deletions). Studies have shown that the E3gene play key roles in the virus infection and host immune regulation. E2and E4genes are related with the transcriptional regulation, DNA recombination and virus assembly process. Drug candidates based on the adenovirus vector, such as ONYX-015(dl1520), have been studied in vivo and in vitro, and even has entered the clinical research stage. However, due to the vice reactions reported of the related clinical experiments in adenovirus, adenovirus vector candidate drug’s safety has been questioned. Since the half-life of adenovirus vectors are shorter, and there is the problem of anti-vector immune. People are trying to increase the drug dose to enhance its anti-tumor effect, but this method may produce liver toxicity and immune side reactions. Based on the above reasons, the application of adenovirus vector system in the drug candidate is restricted. In order to overcome the above drawbacks, extensive research has carried out, which includes the use of other serotypes of adenovirus preparing an adenovirus vector, the transformation of the capsid protein of an adenovirus vector to prepare a virus/non-viral hybrid vectors.In previous study, we constructed a recombinant adenovirus Ad-HN-PEG3p-E1a. The recombinant virus can replicate specifically in tumor cells through PEG3p promoter and the tumor-specific killing activity of the NDV HN. MTT assay results show that, when infected with a dose of100MOI or10MOI, Ad-HN-PEG3p-E1a inhibited HepG-2cells successfully, and the antitumor effects was obvious in4d. But when the infectious dose was1MOI, the inhibitory effect is relatively weak. As to L02cells, Ad-HN-PEG3p-E1a produced no significantly inhibition. In addition, annexin V staining experiment results show that, although Ad-HN-PEG3p-E1a, Ad-EGFP-PEG3p-E1a and Ad-HN exhibited inhibitory effects, slightly higher proportion of apoptosis cells were dected in Ad-HN-PEG3p-E1a treated cells. The above experiment demonstrates that Ad-HN-PEG3p-E1a inhibited HepG-2tumor cells by inducing apoptosis.Antitumor effects were also studied in vivo. The results showed that although the solid tumors were not completely removed, significantly delay of the development of solid tumors was observed. In addition, the infection of HepG-2tumor cells with Ad-HN-PEG3p-E1A could stimulate anti-tumor cytokine of NK and reinforced the killing of NK. There were no obvious side effects of Ad-HN-PEG3p-E1a were observed in the in vivo studies. Therefore, Ad-HN-PEG3p-E1a has the potential applied to the field of cancer treatment and research.