Reexpression of Human Somatostatin Receptor Gene 2 Gene Mediated by Oncolytic Adenovirus Increases Antitumor Activity of Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand against Pancreatic Cancer

Purpose: Pancreatic cancer continues to pose an enormous challenge to clinicians and cancer scientists. Clinical studies show that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) exerts a potent and tumor-specific proapoptotic activity. However, most pancreatic cancer cells are resistant to TRAIL therapy. Human somatostatin receptor gene 2 (hSSTr2) is lost in 90% of pancreatic carcinoma. Oncolytic viruses are able to selectively lyse cancer cells and represent a promising novel anticancer therapy. Here, we investigated whether oncolytic adenovirus-mediated reexpression of hSSTr2 would enhance TRAIL-induced antitumor efficacy against pancreatic cancer. Experimental Design: The antitumor efficacies of combined or single treatment of hSSTr2 and TRAIL mediated by oncolytic adenovirus were compared in pancreatic cancer cell culture and xenografts. The mechanisms involved in hSSTr2-induced sensitization to TRAIL were studied. Results: Oncolytic adenovirus-mediated reexpression of hSSTr2 potentiated TRAIL-induced tumor growth inhibition in vitro and in vivo. Reexpression of hSSTr2 augmented TRAIL-induced apoptosis against pancreatic cancer cells via up-regulation of death receptor 4 and down-regulation of Bcl-2. Conclusions: hSSTr2 restoration mediated by oncolytic adenovirus enhances TRAIL-induced antitumor efficacy against pancreatic cancer. Combined treatment with oncolytic adenovirus-mediated hSSTr2 and TRAIL gene provides the rationale for a clinical trial in pancreatic cancer. (Clin Cancer Res 2009;15(16):5154-60)