TY - JOUR AB - Reduced expression in immortalized cells (REIC)/Dickkopf (Dkk)-3 is a tumor-suppressor gene and has been studied as a promising therapeutic gene for cancer gene therapy. Intratumoral injection of an adenovirus vector carrying the human REIC/Dkk-3 gene (Ad-REIC) elicits cancer cell‑specific apoptosis and anticancer immune responses. The cytokine-like effect of secretory REIC/Dkk-3 on the induction of dendritic cell (DC)-like cell differentiation from monocytes plays a role in systemic anticancer immunity. In the present study, we generated recombinant full-length and N-terminally truncated REIC/Dkk-3 to characterize the biological activity of the protein. During the purification procedure, we identified a 17 kDa cysteine-rich stable product (C17-REIC) showing limited degradation. Further analysis showed that the C17-REIC domain was sufficient for the induction of DC-like cell differentiation from monocytes. Concomitant with the differentiation of DCs, the REIC/Dkk-3 protein induced the phosphorylation of glycogen synthase kinase 3β (GSK-3β) and signal transducers and activators of transcription (STAT) at a level comparable to that of granulocyte/macrophage colony‑stimulating factor. In a mouse model of subcutaneous renal adenocarcinoma, intraperitoneal injection of full-length and C17-REIC proteins exerted anticancer effects in parallel with the activation of immunocompetent cells such as DCs and cytotoxic T lymphocytes in peripheral blood. Taken together, our results indicate that the stable cysteine-rich core region of REIC/Dkk-3 is responsible for the induction of anticancer immune responses. Because REIC/Dkk-3 is a naturally circulating serum protein, the upregulation REIC/Dkk-3 protein expression could be a promising option for cancer therapy. AD - Department of Biotechnology, Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan Center for Innovative Clinical Medicine, Okayama University Hospital, Okayama, Japan Innovation Center Okayama for Nanobio-Targeted Therapy, Okayama University, Okayama, Japan Department of Cell Biology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan AU - Kinoshita,Rie AU - Watanabe,Masami AU - Huang,Peng AU - Li,Shun-Ai AU - Sakaguchi,Masakiyo AU - Kumon,Hiromi AU - Futami,Junichiro DA - 2015/06/01 DO - 10.3892/or.2015.3885 EP - 2914 IS - 6 JO - Oncol Rep KW - REIC monocyte dendritic cell anticancer immune protein therapy PY - 2015 SN - 1021-335X 1791-2431 SP - 2908 ST - The cysteine-rich core domain of REIC/Dkk-3 is critical for its effect on monocyte differentiation and tumor regression T2 - Oncology Reports TI - The cysteine-rich core domain of REIC/Dkk-3 is critical for its effect on monocyte differentiation and tumor regression UR - https://doi.org/10.3892/or.2015.3885 VL - 33 ER -