Liver cancer is a common and aggressive malignancy, but available treatment approaches remain suboptimal. Cancer targeting Gene-Viro-Therapy (CTGVT) has shown excellent anti-tumor effects in a preclinical study. CTGVT takes advantage of both gene therapy and virotherapy by incorporating an anti-tumor gene into an oncolytic virus vector. Potent anti-tumor activity is achieved by virus replication and exogenous expression of the anti-tumor gene. A dual-regulated oncolytic adenoviral vector designated AdÁAFPÁE1AÁE1B (D55) (AdÁAFPÁD55 for short thereafter) was constructed by replacing the native viral E1A promoter with the simian virus 40 enhancer/a-fetoprotein (AFP) composite promoter (AFPep) based on an E1B-55K-deleted construct, ZD55. AdÁAFPÁD55 showed specific replication and cytotoxicity in AFP-positive hepatoma cells. It also showed enhanced safety in normal cells when compared with the mono-regulated vector ZD55. To improve the anti-hepatoma activities of the virus, the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) gene was introduced into AdÁAFPÁD55. AdÁAFPÁD55-TRAIL exhibited remarkable anti-tumor activities in vitro and in vivo. Treatment with AdÁAFPÁD55-TRAIL can induce both autophagy owing to the AdÁAFPÁD55 vector and caspase-dependent apoptosis owing to the TRAIL protein. Therefore, AdÁAFPÁD55-TRAIL could be a potential anti-hepatoma agent with anti-tumor activities due to AFP-specific replication and TRAIL-induced apoptosis.

Interleukin (IL)-24, a promising therapeutic gene, has been widely used for Cancer Targeting Gene-Viro-Therapy (CTGVT). In this study, IL-24 was inserted into an oncolytic adenovirus in which the E1A gene is driven by an enhanced, short a-fetoprotein (AFP) promoter and the E1B gene is completely deleted to form Ad.enAFP-E1A-DE1B-IL-24. This construct has a potent antitumor effect on liver cancer cell lines in vitro, but little or no effect on normal cell lines, such as L-02 and QSG-7701. In vivo, the complete elimination of Huh-7 liver cancer in nude mice with Ad.enAFP-E1A-DE1B-IL-24 intratumor injection was observed. The design of Ad.enAFP-E1A-DE1B-IL-24 and its potent antitumor effect on liver cancer have not been published previously. The mechanism of the potent antitumor effect of Ad.enAFP-E1A-DE1B-IL-24 is due to the upregulation of GADD34 and intrinsic and extrinsic apoptotic signaling.