title: The microenvironment controls CDX2 homeobox gene expression in colorectal cancer cells.
abstract: The homeobox gene CDX2 plays a major role in development, especially in the gut, and it also acts as a tumor suppressor in the adult colon. Using orthotopic and heterotopic xenografts of human primary colorectal tumor cells and cell lines in nude mice, we addressed the effect of the microenvironment on CDX2 expression. In cells expressing CDX2 at a high level in culture, this level was maintained in subcutaneous grafts but was reduced when implanted into the cecum wall. Reciprocally, in cells with low CDX2 expression in culture, the level remained low in grafts into the cecum wall but was stimulated subcutaneously. In vitro co-cultures showed that CDX2 expression was activated in cells grown on layers of skin fibroblasts but not on intestinal fibroblasts. The stimulation was transcriptional, as assessed by transfection experiments with reporter plasmids containing the murine Cdx2 promoter. Together, these data demonstrate experimentally that CDX2 expression is adaptable and strongly dependent on the microenvironment surrounding the tumor cells. We exclude a role of the Notch pathway in this regulation. The regulation of CDX2 by the microenvironment might be relevant during the process of metastatic dissemination when the gene is transiently turned down in invasive cells.
authors.affiliation: INSERM U682, 3 Avenue Molière, 67200 Strasbourg, France.
authors.forename: Fairouz
authors.initials: F
authors.lastname: Benahmed
authors.forename: Isabelle
authors.initials: I
authors.lastname: Gross
authors.forename: Dominique
authors.initials: D
authors.lastname: Guenot
authors.forename: Frédéric
authors.initials: F
authors.lastname: Jehan
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Martin
authors.forename: Claire
authors.initials: C
authors.lastname: Domon-Dell
authors.forename: Thomas
authors.initials: T
authors.lastname: Brabletz
authors.forename: Michèle
authors.initials: M
authors.lastname: Kedinger
authors.forename: Jean-Noël
authors.initials: JN
authors.lastname: Freund
authors.forename: Isabelle
authors.initials: I
authors.lastname: Duluc
mesh_terms: D000328:Adult; D000818:Animals; D000071616:CDX2 Transcription Factor; D002432:Cecum / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D009368:Neoplasm Transplantation; D011401:Promoter Regions, Genetic; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D014183:Transplantation, Heterologous
chemical_list: D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; C487514:Cdx2 protein, mouse; D018398:Homeodomain Proteins; D009363:Neoplasm Proteins; D051880:Receptors, Notch; D014157:Transcription Factors