Gastroenterology

Gastroenterology

Volume 123, Issue 5, November 2002, Pages 1565-1577
Gastroenterology

Basic–Alimentary Tract
CDX2 regulates liver intestine–cadherin expression in normal and malignant colon epithelium and intestinal metaplasia*,**

https://doi.org/10.1053/gast.2002.36598Get rights and content

Abstract

Background & Aims: The intestine-specific caudal-related homeobox transcription factor CDX2 seems to play a key role in intestinal development and differentiation. Inactivation of one Cdx2 allele predisposes mice to develop colon polyps, and loss of CDX2 expression is a feature of some poorly differentiated colon carcinomas in humans. Conversely, aberrant CDX2 expression is often seen in intestinal metaplasias in the stomach and esophagus and in some gastric carcinomas. To better understand CDX2 function, we sought to define CDX2-regulated genes. Methods: HT-29 colon cancer cells with minimal endogenous CDX2 expression were engineered to express exogenous CDX2, and gene expression changes relative to control cells were assessed using high-density oligonucleotide arrays. Results: The gene for liver intestine (LI)-cadherin (cadherin 17) was strongly induced by CDX2 in HT-29. In other colorectal cancer lines, endogenous CDX2 and LI-cadherin expression were well correlated. Activation of a ligand-regulated form of CDX2 rapidly induced LI-cadherin gene expression, even in the presence of protein synthesis inhibitor. Analysis of the 5'-flanking region of the LI-cadherin gene defined 2 CDX2 responsive elements, and chromatin immunoprecipitation assays indicate CDX2 binds to the elements. In primary colorectal cancers and intestinal metaplasias in the stomach, CDX2 and LI-cadherin expression were tightly correlated. Conclusions: CDX2 regulates LI-cadherin gene expression in normal, metaplastic, and neoplastic tissues of the gastrointestinal tract via binding to elements in the 5'-flanking region of the gene. Given the well-established roles of cadherins in morphogenesis and differentiation, LI-cadherin may be a key factor mediating CDX2 function in intestinal cell fate determination.

GASTROENTEROLOGY 2002;123:1565-1577

Section snippets

Plasmids

A full-length, wild-type CDX2 allele was amplified by polymerase chain reaction (PCR) using hexamer-primed complementary DNA (cDNA) from normal human colon tissue as a template. The CDX2 allele was inserted into the multiple cloning site of the retroviral expression vector pPGS-CMV-CITE-neo (pPGS-neo; provided by G. Nabal, National Institutes of Health, Bethesda, MD), generating the vector pPGS-CDX2. The full-length, wild-type CDX2 allele was also subcloned into the retroviral vector

CDX2 and LI-cadherin expression are tightly correlated in colon carcinoma cells

Like several other human colorectal cancer cell lines, the HT-29 line shows minimal levels of endogenous CDX2 expression.17 To identify candidate CDX2-regulated genes, we generated a polyclonal population of HT-29 colorectal cancer cells expressing high levels of CDX2 by infection of the cells with replication-defective retroviruses carrying a full-length human CDX2 cDNA (Figure 1A).

. CDX2 activates LI-cadherin expression in HT-29 cells. (A) Western blot analysis of CDX2 protein expression in

Discussion

There is now a considerable body of data supporting the notion that the intestine-specific homeobox transcription factor CDX2 has a crucial role in directing intestinal epithelial development and differentiation (reviewed by Silberg et al.).1 However, the means by which it does so remain poorly defined. Presumably, the ability of CDX2 to regulate expression of downstream target genes is crucial in its function in intestinal cell fate specification. To date, only a very limited number of

Acknowledgements

The authors thank A. Friedman, G. Nabel, G. Nolan, J. Wang, and M. M. Taketo for generously providing reagents for the studies described as well as Dr. David Misek for assistance with microarray data.

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    *

    Supported by National Institutes of Health grants CA82223, CA84953, and DK58771.

    **

    Address requests for reprints to: Eric R. Fearon, M.D., Ph.D., Division of Molecular Medicine and Genetics, University of Michigan Medical Center, 4301 MSRB III, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109. e-mail: [email protected]; fax: (734) 647-7979.

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