Transactivation of the Multidrug Resistance 1 Gene by T-Cell Factor 4/β-Catenin Complex in Early Colorectal Carcinogenesis
2000
The mutational inactivation of a tumor suppressor gene,
adenomatous polyposis coli ( APC ), results
in the accumulation of cytoplasmic β-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/β-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/β-catenin complex. Luciferase reporter and
gel retardation assays revealed the TCF4/β-catenin responsive
elements in the promoter of the human MDR1 gene.
Corresponding to the accumulation of β-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.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
33
References
223
Citations
NaN
KQI