Rebamipide induces dendritic cell recruitment to N-methyl-N 0 -nitro-N-nitrosoguanidine (MNNG)-exposed rat gastric mucosa based on IL-1b upregulation Nobutake Yamamichi a,⇑ , Masashi Oka b,2 , Ken-ichi Inada c,3 , Maki Konno-Shimizu a,1 , Natsuko Kageyama-Yahara a,1 , Hideyuki Tamai b,2 , Jun Kato b,2 , Mitsuhiro Fujishiro a,1 , Shinya Kodashima a,1 , Keiko Niimi a,1 , Satoshi Ono a,1 , Yutaka Tsutsumi c,3 , Masao Ichinose b,2 , Kazuhiko Koike a,1 a Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan b Department of Gastroenterology, School of Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama-shi, Wakayama 641-0012, Japan c 1st Department of Pathology, Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan article info Article history: Received 5 June 2012 Available online 23 June 2012 Keywords: Rebamipide Gastric cancer N-methyl-N 0 -nitro-N-nitrosoguanidine Dendritic cell IL-1b CD68 abstract Rebamipide is usually used for mucosal protection, healing of gastric ulcers, treatment of gastritis, etc., but its effects on gastric malignancy have not been elucidated. Using Lewis and Buffalo rat strains treated with peroral administration of N-methyl-N 0 -nitro-N-nitrosoguanidine (MNNG), we evaluated the effect of rebamipide on the induction of tumor-suppressive dendritic cells, which are known to be heterogeneous antigen-presenting cells of bone marrow origin and are critical for the initiation of primary T-cell responses. Using CD68 as a marker for dendritic cells, the stomach pyloric mucosae of Lewis and Buffalo rats were immunohistochemically analyzed in the presence or absence of rebamipide and MNNG. After a 14-day treatment of rebamipide alone, no significant change in number of CD68-expressing cells was detected in either rat strain. However, after concurrent exposure to MNNG for 14 days, treatment with rebamipide slightly increased CD68-positive cells in the Lewis strain, and significantly increased them in the Buffalo strain. Analysis of two chemotactic factors of dendritic cells, IL-1b and TNF-a, in the gastric cancer cells showed that expression of IL-1b, but not TNF-a, was induced by rebamipide in a dose-depen- dent manner. A luciferase promoter assay using gastric SH-10-TC cells demonstrated that an element mediating rebamipide action exists in the IL-1b gene promoter region. In conclusion, rebamipide has potential tumor-suppressive effects on gastric tumorigenesis via the recruitment of dendritic cells, based on the upregulation of the IL-1b gene in gastric epithelial cells. Ó 2012 Elsevier Inc. All rights reserved. 1. Introduction Rebamipide, an amino acid analog of 2(1H)-quinolinone, is clin- ically used for mucosal protection, healing of gastric ulcers, and treatment of gastritis [1,2]. The healing effects depend on the enhancement of mucosal defense, scavenging free radicals, and activation of genes such as cyclooxygenase-2 and some growth fac- tors [2]. In the view of carcinogenesis, however, reports concerning the effects of rebamipide on gastric malignancy have been scarce. In this study, we focused on the recruitment of dendritic cells to examine whether rebamipide has a tumor-suppressive effect on gastric mucosa. Dendritic cells are heterogeneous antigen-presenting cells of bone marrow origin that are critical for the initiation of primary T-cell responses [3,4]. They are thought to play key roles in tumor-specific immune responses via (1) cross-priming of tumor cells and dendritic cells, (2) presentation of tumor antigens through MHC class I, and (3) the generation of CD8+ cytolytic T-cells [4]. We have previously demonstrated that dendritic cells infiltrate the mesenchymal layer of rat stomach during chemical carcinogenesis induced by administration of N-methyl-N 0 -nitro- N-nitrosoguanidine (MNNG) [5]. In our previous study using ACI (sensitive to chemically induced carcinogenesis) and Buffalo (resis- tant to chemically induced carcinogenesis) rat strains, we observed 0006-291X/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.bbrc.2012.06.087 Abbreviations: MNNG, N-methyl-N 0 -nitro-N-nitrosoguanidine; IL-1b, interleu- kin-1b; TNF-a, tumor necrosis factor-a. ⇑ Corresponding author. Fax: +81 358 00 8806. E-mail address: nyamamic-tky@umin.ac.jp (N. Yamamichi). 1 Fax: +81 358 00 8806. 2 Fax: +81 734 45 3616. 3 Fax: +81 562 93 3063. Biochemical and Biophysical Research Communications 424 (2012) 124–129 Contents lists available at SciVerse ScienceDirect Biochemical and Biophysical Research Communications journal homepage: www.elsevier.com/locate/ybbrc