Novel REIC/Dkk-3-encoding adenoviral vector as a promising therapeutic agent for pancreatic cancer

Reduced expression in immortalized cells (REIC)/dickkopf-3 (Dkk-3), a tumor suppressor gene, is downregulated in various cancers. We previously reported the tumor-inhibitory effects of the REIC/Dkk-3 gene, delivered by a conventional adenoviral vector (Ad-CAG-REIC) in pancreatic cancer. Here, we developed an Ad-REIC vector with a novel gene expression system, termed the super gene expression (SGE) system, and assessed its therapeutic effects relative to those of Ad-CAG-REIC in pancreatic cancer cells. Human pancreatic cancer cell lines ASPC1 and MIAPaCa2 were used. REIC/Dkk-3 expression was assessed by western blot analysis. Relative cell viability and apoptotic effects were examined in vitro . The anti-tumor effects of Ad-REIC treatment were assessed in the mouse xenograft model. Compared with Ad-CAG-REIC, Ad-SGE-REIC elicited a significant increase in REIC protein expression in the cells studied. Relative to Ad-CAG-REIC, Ad-SGE-REIC reduced cell viability and induced apoptosis in the ASPC1 and MIAPaCa2 cell lines in vitro , and achieved superior tumor growth inhibition in the mouse xenograft model. Compared with conventional Ad-REIC agents, Ad-SGE-REIC provided enhanced inhibitory effects against tumor growth. Our results indicate that Ad-SGE-REIC is an innovative therapeutic tool for pancreatic cancer.