Theraputic Effects Of The Oncolytic Adenovirus Expressing NDV HN On Hepatoma Carcinoma Cell BEL-7402 And Metastasis Models

Newcastle disease virus (NDV) is a paramyxovirus with a negative single-stranded RNA genome which causes inflammation of the respiratory and gastrointestinal tract in a wide variety of poultry species. NDV can also infect humans and cause mild flu-like symptoms and/or laryngitis. NDV targeted vaccines have reached economical significance in veterinary medicine where they are used to protect poultry against respiratory diseases caused by this virus. It is known that this avian virus has anti-tumor properties. Cassel, who had already in the 1960s described the anti-tumor properties of NDV, developed the oncolytic substrain NDV 73T which was then used to produce melanoma oncolysates as vaccines for clinical applications. The observation that NDV replicates much more efficiently in cancer cells than in most normal cells has prompted much interest in NDV as a potential anti-cancer agent.NDV expresses two membrane viral spike proteins, the hemagglutinin-neuraminidase (HN) and fusion protein. The HN protein is a 74 kDa multifunctional membrane class II glycoprotein which protrudes spike-like from the viral envelope. The HN glycoprotein not only mediates recognition of sialic acid containing receptors but also possesses neuraminidase activity (NA) which can cleave the sialic acid on those receptors. The co-presence of both receptor recognition activity and NA on the same protein is in contrast to site of the influenza virus, in which the two activities are performed by independent spike structures. In vitro studies showed that the NDV HN protein which connects with the outer virionic membrane through a hydrophobic region of the N-terminus is one of the major structural proteins of NDV. The HN protein regulates infection and replication of the virus by interacting with sialic acid components on the surface of the target cells.In 1996, the avirulent NDVcc was isolated in Changchun, PR China, by Kuo-shi Jin et al. In previous studies, we showed that NDVcc had the features of an oncolytic virus and that the NDVcc HN gene played an important role in anti-tumor activities of NDVcc. In contrast to the influenza virus which has independent structures performing the initial cell attachment and sialic cleavage functions, a number of studies showed that the NDV HN glycoprotein mediates both of these activities. As an adjuvant for inducing anti-tumor immune responses, the HN protein can activate DCs, monocytes, NK cells and stabilize activated T cells and activates cells to produce theβ-chain of the IL-12 receptor. Moreover, the HN protein can activate DCs to generate large amounts of IFN-a and up-regulate a series of factors associated with antigen recognition, cell interaction, cell adhesion and cytotoxicity.Sialic acid, which is generally found in the non-reducing terminus of most glycoproteins and glycolipids, is associated with tumor cell behavior, such as invasiveness and metastasis, via interfering with signal transduction and cell growth properties. The NDV HN protein can recognize and hydrolyze these sialic acid components. Furthermore, it is known that the NDV HN protein can stimulate cells such as dendritic cells (DC) to produce high levels of interferon-a (IFN-a) and activate macrophages, natural killer (NK) cells and T cells. Additionally, the distinct structure of HN displayed on the tumor cell surface can be recognized by the immune system and strengthen the cytotoxicity. All these properties render the NDV HN protein as an attractive candidate for tumor immunotherapy.To investigate the stimulated activity of T cells and the anti-tumor properties of hemagglutinin-neuraminidase (HN) of Newcastle disease virus (NDV) strain Changchun (NDVcc). In this study, we evaluated the antitumoral effects on hepatoma cells (human BEL-7402 and mouse H22 cells) in vitro and in vivo. The in vitro anti-tumor effects were examined by nuclear detection, cell membrane evaluation, mitochondria trans-membrane potential assay and reactive oxygen species assay. The results showed that the recombinant adenoviruses induced apoptosis of BEL-7402 cells effectively. Furthermore, the in vivo anti-tumor effects were evaluated by exprimetnal animals. The results showed that the recombinant adenoviruses prolonged the mean survival of the animals, activated NK/CTL cells and inclined the immune to Thl preponderance.