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Background and Aim Reduced expression in immortalized cells (REIC)/dickkopf-3 (Dkk-3) is a tumor suppressor gene that is downregulated in various cancers. In our previous study of prostate cancer, the REIC/Dkk-3-expressing adenoviral vector (Ad-REIC) was found to induce cancer-selective apoptosis. This study recently developed a novel super gene expression (SGE) system and used this system to re-construct an Ad-REIC vector, termed the Ad-SGE-REIC, to achieve more effective therapeutic outcomes. In this study, the therapeutic effects of Ad-SGE-REIC on hepatocellular carcinoma (HCC) was assessed. Methods Human HCC cell lines (HLE, Huh7, HepG2, HLF, SK-Hep1, and PLC), human HCC tissues, and mouse HCC cell line (Hepa1-6) were used in this study. REIC/Dkk-3 expression was assessed by immunoblotting and immunohistochemistry. The relative cell viability and the apoptotic effect were examined in vitro, and the anti-tumor effects of Ad-SGE-REIC treatment were analyzed in the mouse xenograft model. This study additionally assessed anti-tumor immunological effects on the immunocompetent mice. Results REIC/Dkk-3 expression was decreased in HCC cell lines and HCC tissues. Ad-SGE-REIC reduced cell viability and induced apoptosis in HCC cell lines (HLE and Huh7), inhibited tumor growth in the mouse xenograft model, and demonstrated in vivo anti-cancer immunostimulatory effects on the HCC cell line (Hepa1-6). Conclusions Ad-SGE-REIC treatment not only enhanced cell killing effects in vitro but also elicited significant therapeutic effects, with tumor growth suppression, in vivo. REIC/Dkk-3 gene therapy using Ad-SGE-REIC potentially represents an innovative new therapeutic tool for HCC. [ABSTRACT FROM AUTHOR]

Background and Aim Reduced expression in immortalized cells/dickkopf-3 (REIC/DKK3) is a reported tumor suppressor gene and has potential to become an innovative therapy for various cancers. We examined the antitumor immunological effects of human REIC/DKK3 protein against pancreatic cancer. Methods Activation of extracellular signal-regulated kinases 1 and 2, mammalian target of rapamycin, and signal transducer and activator of transcription 3 by REIC/DKK3 protein was assessed in human peripheral blood mononuclear cells using immunoblotting. Pancreatic cancer cell lines (AsPC-1 and MIA Paca-2) were cocultured with peripheral blood mononuclear cells, and the anticancer effects of REIC/DKK3 protein were assessed using the methyl thiazole tetrazolium, cytotoxicity, and enzyme-linked immunospot assays. The antitumor immunological effects of the combined treatment with REIC/DKK3 protein and peripheral blood mononuclear cells were also assessed in a pancreatic cancer model using non-obese diabetic/severe combined immunodeficiency mice. Results The REIC/DKK3 protein activated extracellular signal-regulated kinases 1 and 2, mammalian target of rapamycin, and signal transducer and activator of transcription 3 in peripheral blood mononuclear cells. REIC/DKK3 protein inhibited in vitro cancer cell viability and enhanced cytotoxicity when incubated with peripheral blood mononuclear cells. REIC/DKK3 protein induced significant production of interferon gamma from lymphocytes incubated with pancreatic cancer cells, indicating that CD8+ T cells were activated in the peripheral blood mononuclear cells when cocultured with AsPC-1 and MIA Paca-2 in the presence of REIC/DKK3 protein. Combined treatment with REIC/DKK3 protein and peripheral blood mononuclear cells produced in vivo anticancer immunostimulatory effects on pancreatic cancer cells. Conclusions The REIC/DKK3 protein and peripheral blood mononuclear cells synergistically enhanced anticancer immunological effects against pancreatic cancer cells. The observed immunomodulatory effect of combined treatment likely occurs in adenovirus-mediated REIC/DKK3 gene therapy and provides important clues to the therapeutic mechanisms involving immune cells. [ABSTRACT FROM AUTHOR]