title: Transactivation of the multidrug resistance 1 gene by T-cell factor 4/beta-catenin complex in early colorectal carcinogenesis.
abstract: The mutational inactivation of a tumor suppressor gene, adenomatous polyposis coli (APC), results in the accumulation of cytoplasmic beta-catenin protein and the activation of T-cell factor (TCF)/lymphoid enhancer factor transcriptional factors. A colorectal carcinoma cell line, DLD-1, was engineered to suppress transactivation by the TCF4/beta-catenin complex in a dominant-negative manner under the strict control of the tetracycline regulatory system. A large-scale comparison of the expression profiles, using two-color fluorescence hybridization of cDNA microarray, led to the identification of MDR1 as a target gene of the TCF4/beta-catenin complex. Luciferase reporter and gel retardation assays revealed the TCF4/beta-catenin responsive elements in the promoter of the human MDR1 gene. Corresponding to the accumulation of beta-catenin, expression of the MDR1 gene product was steadily up-regulated in adenomas and adenocarcinomas of 10 patients with familial adenomatous polyposis. In combination with cell proliferative activities of c-myc and cyclin D1, MDR1 may initiate colorectal tumorigenesis by suppressing cell death pathways programmed in intestinal epithelial cells.
authors.affiliation: Pathology Division, National Cancer Center Research Institute, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamada
authors.forename: A S
authors.initials: AS
authors.lastname: Takaoka
authors.forename: Y
authors.initials: Y
authors.lastname: Naishiro
authors.forename: R
authors.initials: R
authors.lastname: Hayashi
authors.forename: K
authors.initials: K
authors.lastname: Maruyama
authors.forename: C
authors.initials: C
authors.lastname: Maesawa
authors.forename: A
authors.initials: A
authors.lastname: Ochiai
authors.forename: S
authors.initials: S
authors.lastname: Hirohashi
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics; D011125:Adenomatous Polyposis Coli / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism / Q000502:physiology*; D004318:Doxycycline / Q000494:pharmacology; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D017491:Genes, APC / Q000235:genetics; D019450:Genes, MDR / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D051820:TCF Transcription Factors; D015534:Trans-Activators; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured; D051176:beta Catenin
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; D015534:Trans-Activators; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors; D051176:beta Catenin; D004318:Doxycycline