CDX2 autoregulation in human intestinal metaplasia of the stomach: impact on the stability of the phenotype
- Rita Barros1,
- Luis Teixeira da Costa1,2,
- João Pinto-de-Sousa3,4,
- Isabelle Duluc5,
- Jean-Noel Freund5,
- Leonor David1,4,
- Raquel Almeida1,4
- 1Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal
- 2ICAAM, Universidade de Évora, Évora, Portugal
- 3Department of Surgery, Hospital S. João, Porto, Portugal
- 4Faculty of Medicine of the University of Porto, Porto, Portugal
- 5Inserm U682, Strasbourg, France
- Correspondence to Raquel Almeida, IPATIMUP, Rua Dr Roberto Frias s/n, 4200-465 Porto, Portugal;
- Revised 8 October 2010
- Accepted 11 October 2010
- Published Online First 9 December 2010
Background and aims Intestinal metaplasia (IM) is a gastric preneoplastic lesion that appears following Helicobacter pylori infection and confers an increased risk for development of cancer. It is induced by gastric expression of the intestine-specific transcription factor CDX2. The regulatory mechanisms involved in triggering and maintaining gastric CDX2 expression have not been fully elucidated. The Cdx2+/− mouse develops intestinal polyps with gastric differentiation and total loss of Cdx2 expression in the absence of structural loss of the second allele, suggesting a regulatory defect. This putative haplo-insufficiency, together with the apparent stability of IM, led to the hypothesis that CDX2 regulates its own expression through an autoregulatory loop in both contexts.
Methods Gastrointestinal cell lines were co-transfected with wild-type or mutated Cdx2 promoter constructs and CDX2 expression vector for luciferase assays. Transfection experiments were also used to assess endogenous CDX2 autoregulation, evaluated by RT-PCR, qPCR and western blotting. Chromatin immunoprecipitation was performed in a cell line, mouse ileum and human IM.
Results CDX2 binds to and transactivates its own promoter and positively regulates its expression in gastrointestinal human carcinoma cell lines. Furthermore, CDX2 is bound to its promoter in the mouse ileum and in human gastric IM, providing a major contribution to understanding the relevance of this autoregulatory pathway in vivo.
Conclusion The results of this study demonstrate another layer of complexity in CDX2 regulation by an effective autoregulatory loop which may have a major impact on the stability of human IM, possibly resulting in the inevitable progression of the gastric carcinogenesis pathway.
- Intestinal metaplasia
- gastric carcinoma
- transcriptional regulation, carcinogenesis
- gastric cancer
- gastric pre-cancer
- gene regulation
- molecular pathology
Funding This work was supported by Fundação para a Ciência e a Tecnologia (FCT) (Project PTDC/SAU-OBD/64490/2006) financed by Programa Operacional Ciência e Inovação 2010 do Quadro Comunitário de Apoio III and FEDER. IPATIMUP is an Associate Laboratory of the Portuguese Ministry of Science, Technology and Higher Education and is partially supported by FCT. RB was supported by FCT (SFRH/BD/29622/2006).
Competing interests None.
Ethics approval This study was conducted with the approval of the Hospital S. João, Porto, Portugal.
Provenance and peer review Not commissioned; externally peer reviewed.
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