title: The cysteine-rich core domain of REIC/Dkk-3 is critical for its effect on monocyte differentiation and tumor regression.
abstract: 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.
authors.affiliation: Department of Biotechnology, Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Kinoshita
authors.affiliation: Center for Innovative Clinical Medicine, Okayama University Hospital, Okayama, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Innovation Center Okayama for Nanobio-Targeted Therapy, Okayama University, Okayama, Japan.
authors.forename: Peng
authors.initials: P
authors.lastname: Huang
authors.affiliation: Innovation Center Okayama for Nanobio-Targeted Therapy, Okayama University, Okayama, Japan.
authors.forename: Shun-Ai
authors.initials: SA
authors.lastname: Li
authors.affiliation: Department of Cell Biology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
authors.forename: Masakiyo
authors.initials: M
authors.lastname: Sakaguchi
authors.affiliation: Innovation Center Okayama for Nanobio-Targeted Therapy, Okayama University, Okayama, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kumon
authors.affiliation: Department of Biotechnology, Division of Chemistry and Biochemistry, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Futami
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002454:Cell Differentiation / Q000235:genetics*; D045744:Cell Line, Tumor; D018925:Chemokines; D003545:Cysteine / Q000235:genetics; D003713:Dendritic Cells / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007274:Injections, Intraperitoneal; D036341:Intercellular Signaling Peptides and Proteins / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics*; D007680:Kidney Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D009000:Monocytes / Q000378:metabolism / Q000473:pathology; D017434:Protein Structure, Tertiary / Q000235:genetics; D050791:STAT Transcription Factors / Q000235:genetics; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000473:pathology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018925:Chemokines; C498624:DKK3 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D050791:STAT Transcription Factors; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3; D003545:Cysteine