title: Transgenic Cdx2 induces endogenous Cdx1 in intestinal metaplasia of Cdx2-transgenic mouse stomach.
abstract: Cdx1 and Cdx2, which are transcription factors regulating normal intestinal development, have been studied as potential key molecules in the pathogenesis of the precancerous intestinal metaplasia of the human stomach. However, the regulation of Cdx1 expression in the intestinal metaplasia is poorly understood. Cdx2-expressing gastric mucosa of Cdx2-transgenic mouse stomach was replaced by intestinal metaplastic mucosa. The aim of this study was to investigate the following: (a) Cdx1 expression in the intestinal metaplastic mucosa of the Cdx2-transgenic mouse stomach; and (b) the relationship between Cdx1 and Cdx2. A mouse model of intestinal metaplasia, the Cdx2-transgenic mouse, was used to investigate Cdx1 gene expression by RT-PCR. DNA methylation profile analysis was performed by bisulfite sequencing, and the interaction of Cdx2 with the Cdx1 promoter was examined by chromatin immunoprecipitation assay, electrophoretic mobility shift assay, and luciferase reporter assays. Cdx2 mRNA was expressed in the Cdx2-transgenic mouse stomach. However, endogenous Cdx2 mRNA was not expressed in the intestinal metaplasia of the Cdx2-transgenic mouse stomach. On the other hand, endogenous Cdx1 mRNA and protein were expressed in the intestinal metaplasia of the Cdx2-transgenic mouse stomach. The Cdx1 promoter was unmethylated in the intestinal metaplasia of the Cdx2-transgenic mouse stomach. Chromatin immunoprecipitation assay and electrophoretic mobility shift assay showed that Cdx2 was bound to the Cdx1 promoter region in the intestinal metaplasia and the normal intestine. Cdx2 upregulated and siRNA-Cdx2 downregulated the transcriptional activity of the Cdx1 gene in the human gastric carcinoma cell lines AGS, MKN45, and MKN74. In conclusion, transgenic Cdx2 induced endogenous Cdx1 through the binding of Cdx2 to the unmethylated Cdx1 promoter region in the intestinal metaplasia of the Cdx2-transgenic mouse stomach.
authors.affiliation: Department of Medicine, Division of Gastroenterology, Jichi Medical University, Tochigi, Japan. muto@jichi.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mutoh
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hayakawa
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Miho
authors.initials: M
authors.lastname: Sashikawa
authors.forename: Kentaro
authors.initials: K
authors.lastname: Sugano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000071616:CDX2 Transcription Factor; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D005753:Gastric Mucosa / Q000378:metabolism / Q000473:pathology*; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000473:pathology*; D008679:Metaplasia / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
chemical_list: D000071616:CDX2 Transcription Factor; C491272:Cdx1 protein, mouse; C487514:Cdx2 protein, mouse; D018398:Homeodomain Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors