Dataset Information

Genomic structure and alterations of homeobox gene CDX2 in colorectal carcinomas.

ABSTRACT: Expression of CDX2, a caudal-related homeobox gene, was found to be decreased in colorectal carcinomas. Heterozygous null mutant mice as to Cdx2 develop multiple intestinal adenomatous polyps. To clarify the role of CDX2 in colorectal carcinogenesis, we determined its genomic structure, and searched for mutations of CDX2 in 49 sporadic colorectal carcinomas and ten hereditary non-polyposis colorectal cancers (HNPCC) without microsatellite instability. None of them exhibited a mutation. We further examined 19 HNPCC carcinomas with microsatellite instability for mutations in a (G)7 repeat site within CDX2. One of them (5.3%) exhibited one G insertion. Loss of heterozygosity was observed in 2 of the 20 (10%) informative sporadic carcinomas, and in one of the three (33.3%) informative HNPCC cancers. These data indicate that CDX2 may play only a minor role in colorectal carcinogenesis.

SUBMITTER: Yagi OK

PROVIDER: S-EPMC2362430 | biostudies-other | 1999 Feb

REPOSITORIES: biostudies-other

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Genomic structure and alterations of homeobox gene CDX2 in colorectal carcinomas.

Yagi O K OK Akiyama Y Y Yuasa Y Y

British journal of cancer 19990201 3-4

Expression of CDX2, a caudal-related homeobox gene, was found to be decreased in colorectal carcinomas. Heterozygous null mutant mice as to Cdx2 develop multiple intestinal adenomatous polyps. To clarify the role of CDX2 in colorectal carcinogenesis, we determined its genomic structure, and searched for mutations of CDX2 in 49 sporadic colorectal carcinomas and ten hereditary non-polyposis colorectal cancers (HNPCC) without microsatellite instability. None of them exhibited a mutation. We furthe ...[more]

PMID: 10027310

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Project description:To explore the role of homeobox genes in the intestine, the human colon adenocarcinoma cell line Caco2-TC7 has been stably transfected with plasmids synthesizing Cdx1 and Cdx2 sense and antisense RNAs. Cdx1 overexpression or inhibition by antisense RNA does not markedly modify the cell differentiation markers analyzed in this study. In contrast, Cdx2 overexpression stimulates two typical markers of enterocytic differentiation: sucrase-isomaltase and lactase. Cells in which the endogenous expression of Cdx2 is reduced by antisense RNA attach poorly to the substratum. Conversely, Cdx2 overexpression modifies the expression of molecules involved in cell-cell and cell-substratum interactions and in transduction process: indeed, E-cadherin, integrin-beta4 subunit, laminin-gamma2 chain, hemidesmosomal protein, APC, and alpha-actinin are upregulated. Interestingly, most of these molecules are preferentially expressed in vivo in the differentiated villi enterocytes rather than in crypt cells. Cdx2 overexpression also results in the stimulation of HoxA-9 mRNA expression, an homeobox gene selectively expressed in the colon. In contrast, Cdx2-overexpressing cells display a decline of Cdx1 mRNA, which is mostly found in vivo in crypt cells. When implanted in nude mice, Cdx2-overexpressing cells produce larger tumors than control cells, and form glandular and villus-like structures. Laminin-1 is known to stimulate intestinal cell differentiation in vitro. In the present study, we demonstrate that the differentiating effect of laminin-1 coatings on Caco2-TC7 cells is accompanied by an upregulation of Cdx2. To further document this observation, we analyzed a series of Caco2 clones in which the production of laminin-alpha1 chain is differentially inhibited by antisense RNA. We found a positive correlation between the level of Cdx2 expression, that of endogenous laminin-alpha1 chain mRNA and that of sucrase-isomaltase expression in these cell lines. Taken together, these results suggest (a) that Cdx1 and Cdx2 homeobox genes play distinct roles in the intestinal epithelium, (b) that Cdx2 provokes pleiotropic effects triggering cells towards the phenotype of differentiated villus enterocytes, and (c) that Cdx2 expression is modulated by basement membrane components. Hence, we conclude that Cdx2 plays a key role in the extracellular matrix-mediated intestinal cell differentiation.

Project description:Background and aimsThe mechanism of transformation to intestinal metaplasia in Barrett's oesophagus has not been clarified. We investigated the effects of various bile acids on expression of the caudal related homeobox gene Cdx2 in cultured oesophageal squamous epithelial cells. In addition, morphological and histochemical changes in squamous cells to intestinal epithelial cells were studied in response to bile acid induced expression of Cdx2.MethodsA rat model of Barrett's oesophagus was created by anastomosing the oesophagus and jejunum, and Cdx2 expression was investigated by immunohistochemistry. Also, the response of various bile acids on Cdx2 gene expression was studied in the human colon epithelial cell lines Caco-2 and HT-29, as well as in cultured rat oesophageal squamous epithelial cells using a Cdx2 promoter luciferase assay. In addition, primary cultured oesophageal squamous epithelial cells were transfected with Cdx2 expression vectors and their possible transformation to intestinal-type epithelial cells was investigated.ResultsOesophagojejunal anastomoses formed intestinal goblet cell metaplasia in rat oesophagus specimens and metaplastic epithelia strongly expressed Cdx2. When the effects of 11 types of bile acids on Cdx2 gene expression were examined, only cholic acid (CA) and dehydrocholic acid dose dependently increased Cdx2 promoter activity and Cdx2 protein production in Caco-2 and HT-29 cells, and cultured rat oesophageal keratinocytes. Results from mutation analysis of Cdx2 promoter suggested that two nuclear factor kappaB (NFkappaB) binding sites were responsible for the bile acid induced activation of the Cdx2 promoter. When bile acids were measured in oesophageal refluxate of rats with experimental Barrett's oesophagus, the concentration of CA was found to be consistent with the experimental dose that augmented Cdx2 expression in vitro. Furthermore, transfection of the Cdx2 expression vector in cultured rat oesophageal keratinocytes induced production of intestinal-type mucin, MUC2, in cells that expressed Cdx2.ConclusionsWe found that CA activates Cdx2 promoter via NFkappaB and stimulates production of Cdx2 protein in oesophageal keratinocytes with production of intestinal-type mucin. This may be one of the mechanisms of metaplasia in Barrett's oesophagus.

Dataset Information

Genomic structure and alterations of homeobox gene CDX2 in colorectal carcinomas.

Publications

Genomic structure and alterations of homeobox gene CDX2 in colorectal carcinomas.

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