title: Human MUC2 mucin gene is transcriptionally regulated by Cdx homeodomain proteins in gastrointestinal carcinoma cell lines.
abstract: In intestinal metaplasia and 30% of gastric carcinomas, MUC2 intestinal mucin and the intestine-specific transcription factors Cdx-1 and Cdx-2 are aberrantly expressed. The involvement of Cdx-1 and Cdx-2 in the intestinal development and their role in transcription of several intestinal genes support the hypothesis that Cdx-1 and/or Cdx-2 play important roles in the aberrant intestinal differentiation program of intestinal metaplasia and gastric carcinoma. To clarify the mechanisms of transcriptional regulation of the MUC2 mucin gene in gastric cells, pGL3 deletion constructs covering 2.6 kb of the human MUC2 promoter were used in transient transfection assays, enabling us to identify a relevant region for MUC2 transcription in all gastric cell lines. To evaluate the role of Cdx-1 and Cdx-2 in MUC2 transcription we performed co-transfection experiments with expression vectors encoding Cdx-1 and Cdx-2. In two of the four gastric carcinoma cell lines and in all colon carcinoma cell lines we observed transactivation of the MUC2 promoter by Cdx-2. Using gel shift assays we identified two Cdx-2 binding sites at -177/-171 and -191/-187. Only simultaneous mutation of the two sites resulted in inhibition of Cdx-2-mediated transactivation of MUC2 promoter, implying that both Cdx-2 sites are active. Finally, stable expression of Cdx-2 in a gastric cell line initially not expressing Cdx-2, led to induction of MUC2 expression. In conclusion, this work demonstrates that Cdx-2 activates the expression of MUC2 mucin gene in gastric cells, inducing an intestinal transdifferentiation phenotype that parallels what is observed both in intestinal metaplasia and some gastric carcinomas.
authors.affiliation: Institute of Molecular Pathology and Immunology (IPATIMUP), University of Porto, Rua Dr. Roberto Frias s/n, 4200 Porto, Portugal. pmesquita@ipatimup.pt
authors.forename: Patrícia
authors.initials: P
authors.lastname: Mesquita
authors.forename: Nicolas
authors.initials: N
authors.lastname: Jonckheere
authors.forename: Raquel
authors.initials: R
authors.lastname: Almeida
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Ducourouble
authors.forename: Jacinta
authors.initials: J
authors.lastname: Serpa
authors.forename: Elisabete
authors.initials: E
authors.lastname: Silva
authors.forename: Pascal
authors.initials: P
authors.lastname: Pigny
authors.forename: Filipe Santos
authors.initials: FS
authors.lastname: Silva
authors.forename: Celso
authors.initials: C
authors.lastname: Reis
authors.forename: Debra
authors.initials: D
authors.lastname: Silberg
authors.forename: Isabelle
authors.initials: I
authors.lastname: Van Seuningen
authors.forename: Leonor
authors.initials: L
authors.lastname: David
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D000071616:CDX2 Transcription Factor; D045744:Cell Line, Tumor; D005770:Gastrointestinal Neoplasms / Q000473:pathology*; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D055262:Mucin-2; D009077:Mucins / Q000096:biosynthesis / Q000235:genetics*; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D015534:Trans-Activators; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: C491273:CDX1 protein, human; D000071616:CDX2 Transcription Factor; D018398:Homeodomain Proteins; C524625:MUC2 protein, human; D055262:Mucin-2; D009077:Mucins; D015534:Trans-Activators