E2F Promoter-Regulated Oncolytic Adenovirus with p16 Gene Induces Cell Apoptosis and Exerts Antitumor Effect on Gastric Cancer

Abstract

Replication-competent adenovirus (RCAd) constitutes an alternative in cancer therapy. For obtaining advanced RCAd generations with high oncolytic capability and a good safety profile, we constructed an E2F promoter-regulated RCAd carrying p16 gene, AdE2F-p16, in which the E1a gene was controlled by the E2F promoter. The experimental data showed that the E2F promoter endowed AdE2F-p16 with high specificity in cancer cells. While rarely replicating in normal cells, AdE2F-p16 could replicate in p16-deficient cancer cells, with 2,937- to 160,000-fold increased replicative capability in different cancer cell lines. AdE2F-p16 expressed p16 within cancer cells and led to potent antitumor efficacy in gastric cancer xenografts in nude mice, with a tumor inhibition rate of 59.14%. Due to the combined effects of cancer cell apoptosis induced by p16 expression and oncolysis by virus replication, the E2F promoter-regulated, p16-armed RCAd provides a promising strategy for cancer gene therapy.

Chemotherapy and Oncolytic Virotherapy: Advanced Tactics in the War against Cancer

“…To further enhance their oncolytic effects, transgenes encoding pro-apoptotic proteins are inserted into OVs to subvert cell death machinery. These proteins include various death-inducing ligands such as TNF-related apoptosis-inducing ligand (TRAIL) (25, 26), Fas ligand (FasL) (27), and tumor suppressor genes (e.g., p53, p16) (28, 29). Alternatively, small hairpin RNA targeting factors can be inserted to silence genes involved in cell survival or proliferation, including hTERT and ki67 (30) or MYCN oncogene (31).…”

Tumor Suppressor Gene p16/INK4A/CDKN2A and Its Role in Cell Cycle Exit, Differentiation, and Determination of Cell Fate

“…p16 along with p27 inhibits angioplasty-induced neointimal hyperplasia and coronary artery occlusion , inhibits proliferation in neointimal hyperplasia , and a wide range of other tumor types (Patel et al, 2000). Ectopic expression of p16 by replication-competent adenovirus leads to potent anti-tumor effects in gastric cancer xenografts in nude mice (Ma et al, 2009) while p16 transfection along with cisplatin treatment increased senescence and growth inhibition in non-small cell lung cancer xenografts in mice (Fang et al, 2007). Ectopic p16 expression was able to induce growth arrest in pancreatic carcinoma JF305 cell lines , human laryngeal squamous cell carcinoma Fu et al, 2004), and inhibit experimental lung metastasis in Balb/c nude mice (Kim et al, 2003), inhibit cell growth in nasopharyngeal carcinoma , and a murine model of head and neck cancer (Rhee et al, 2003), human mesothelioma (Yang et al, 2003), and suppress tumor growth by glioblastoma cells in vivo and in vitro (Adachi et al, 2002).…”

Adenovirus-Based Gene Therapy for Cancer

“…Thereby, AdE2F-p16 overcomes the disadvantages of low transfer rate and poor gene expression compared with the replicationdeficient adenovirus vectors. In summary, the E2F promoter-regulated, p16-armed CRAd can mediate the effective expression of transgene in cancer cells, and displays a satisfactory therapeutic effect for cancer (Ma et al, 2009). To further investigate the molecular mechanisms of P16-induced apoptosis, the consequential study found that the adenovirus-mediated P16 reactivation lead to an inhibition of Akt signaling pathway and a downregulation of survivin expression in hepatocellular carcinoma cells .…”

“…Reactivation of P16 by transferring the p16 gene into cancer cells induced cell G1 arrest and apoptosis (Chen et al, 2005), suggesting that the p16 gene may have a good future application in cancer gene therapy. The E2F promoter-regulated CRAd armed with the p16 gene, AdE2F-p16, was constructed (Ma et al, 2009). With the selective replication of AdE2F-p16 under the control of the E2F promoter, AdE2F-p16 expressed P16 with high levels in cancer cells.…”

“…These viruses are genetically modified to target, infect and replicate in cancer cells causing them to lyse with an improved, superior efficacy compared to non-replicating adenoviral vector which lacks the E1 genes. Here, combined with the studies of our group (Fang et al, 2009(Fang et al, , 2010He et al, 2009He et al, , 2010Hu et al, 2010;Ma et al, 2009;Su et al, 2004Su et al, , 2006aSu et al, , 2006bSu et al, , 2008aSu et al, , 2008b, we review the development of oncolytic adenovirus-based gene therapy for cancer, and figured the potential prospects of gene therapy in cancer treatment.…”