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At least 19 recordsLinked to original sources
PubMed2005

Cdk2-dependent phosphorylation of homeobox transcription factor CDX2 regulates its nuclear translocation and proteasome-mediated degradation in human intestinal epithelial cells.

By having demonstrated previously that p27(Kip1), a potent inhibitor of G(1) cyclin-cyclin-dependent kinases complexes, increases markedly during intestinal epithelial cell differentiation, we examined the effect of p27(Kip1) on the activity of the transcription factor CDX2. The present results revealed the following. 1) p27(Kip1) interacts with the CDX2 transcription factor. 2) In contrast to CDX2 mRNA levels, CDX2 protein expression levels significantly increased as soon as Caco-2/15 cells reached confluence, slowed their proliferation, and began their differentiation. The mechanism of CDX2 regulation is primarily related to protein stability, because inhibition of proteasome activity increased CDX2 levels. The half-life of CDX2 protein was significantly enhanced in differentiated versus undifferentiated proliferative intestinal epithelial cells. 3) Cdk2 interacted with CDX2 and phosphorylated CDX2, as determined by pull-down glutathione S-transferase and immunoprecipitation experiments with proliferating undifferentiated Caco-2/15 cell extracts. 4) Treatment of Caco-2/15 cells with MG132 (a proteasome inhibitor) and (R)-roscovitine (a specific Cdk2 inhibitor) induced an increase in CDX2 protein levels. 5) Conversely, ectopic expression of Cdk2 resulted in decreased expression of CDX2 protein. 6) Of note, treatment of proliferative Caco-2/15 cells with (R)-roscovitine or leptomycin (an inhibitor of nuclear export through CRM1) led to an accumulation of CDX2 into the nucleus. These data suggest that CDX2 undergoes CRM1-dependent nuclear export and cytoplasmic degradation in cells in which Cdk2 is activated, such as in proliferative intestinal epithelial cells. The targeted degradation of CDX2 following its phosphorylation by Cdk2 identifies a new mechanism through which CDX2 activity can be regulated in coordination with the cell cycle machinery.

Active Transport, Cell Nucleus↗
PubMed2001

Intestinal epithelial cell differentiation involves activation of p38 mitogen-activated protein kinase that regulates the homeobox transcription factor CDX2.

The intracellular signaling pathways responsible for cell cycle arrest and differentiation along the crypt-villus axis of the human small intestine remain largely unknown. p38 mitogen-activated protein kinases (MAPKs) have recently emerged as key modulators of various vertebrate cell differentiation processes. In order to elucidate further the mechanism(s) responsible for the loss of proliferative potential once committed intestinal cells begin to differentiate, the role and regulation of p38 MAPK with regard to differentiation were analyzed in both intact epithelium as well as in well established intestinal cell models recapitulating the crypt-villus axis in vitro. Results show that phosphorylated and active forms of p38 were detected primarily in the nuclei of differentiated villus cells. Inhibition of p38 MAPK signaling by 2-20 microm SB203580 did not affect E2F-dependent transcriptional activity in subconfluent Caco-2/15 or HIEC cells. p38 MAPK activity dramatically increased as soon as Caco-2/15 cells reached confluence, whereas addition of SB203580 during differentiation of Caco-2/15 cells strongly attenuated sucrase-isomaltase gene and protein expression as well as protein expression of villin and alkaline phosphatase. The binding of CDX2 to the sucrase-isomaltase promoter and its transcriptional activity were significantly reduced by SB203580. Pull-down glutathione S-transferase and immunoprecipitation experiments demonstrated a direct interaction of CDX3 with p38. Finally, p38-dependent phosphorylation of CDX3 was observed in differentiating Caco-2/15 cells. Taken together, our results indicate that p38 MAPK may be involved in the regulation of CDX2/3 function and intestinal cell differentiation.

CDX2 Transcription Factor↗
PubMed2006

[Expression of intestine-specific transcription factor CDX2 in different subtypes of intestinal metaplasia and gastric carcinoma].

BACKGROUND & OBJECTIVE: Intestinal metaplasia (IM) is thought as the precancerous lesion of gastric carcinoma, and CDX2 gene plays important roles in development and differentiation of intestinal epithelium, and maintenance of intestinal phenotype. Recent studies found that CDX2 were expressed aberrantly in IM of chronic atrophic gastritis (CAG) and some gastric carcinomas, which implied that CDX2 may play an important role in IM formation and gastric carcinogenesis. This study was to investigate the roles of CDX2 in the development and progression of IM and gastric carcinogenesis, and determine the correlation of IM to gastric carcinogenesis. METHODS: A tissue microarray containing 46 cases of CAG with IM, 40 cases of gastric carcinoma, and 32 cases of IM foci in paracancerous tissues was constructed. High iron diamine/alcian blue (HID/AB) and HE staining were used to classify IM and gastric carcinoma, and the expression of CDX2 protein and mRNA in different gastric lesions was assessed with immunohistochemistry and in situ hybridization, respectively. RESULTS: The proportion of type III IM was significantly higher in IM foci in paracancerous tissues than in CAG with IM (56.25% vs. 21.74%, P<0.01). The positive rates of CDX2 protein were 69.56% in IM foci in CAG, 53.13% in IM foci in paracancerous tissues, and 42.50% in gastric carcinomas, and the positive rates of CDX2 mRNA were 63.04%, 46.87%, and 35.00%, respectively. The positive rates were significantly lower in gastric cancer than in IM in CAG (P<0.01), but there was no significant difference between gastric cancer and IM foci in paracancerous tissues (P>0.05). The expression of CDX2 protein and mRNA was significantly higher in intestinal-type gastric cancer than in diffuse-type gastric cancer (54.55% vs. 27.78%, 45.45% vs. 22.22%, P<0.05). The expression of CDX2 protein was significantly lower in type III IM than in type I IM (46.42% vs. 79.31%, P<0.05). CONCLUSIONS: CDX2 may play important roles in the development and progression of IM and gastric carcinogenesis.

CDX2 Transcription Factor↗
PubMed2006

Expression of the intestinal transcription factor CDX2 in carcinoid tumors is a marker of midgut origin.

CONTEXT: Carcinoid tumors are classified according to their site of origin into foregut, midgut, or hindgut carcinoids, which have different presentations and prognosis. The intestinal transcription factor CDX2 has been found to be expressed in most intestinal adenocarcinomas but in less than one half of the gastrointestinal carcinoids according to 1 study. OBJECTIVE: To determine whether CDX2 expression in carcinoid tumors varies by the site of origin and whether CDX2 expression is retained in metastatic disease. Design.-Sections of formalin-fixed and paraffin-embedded tissue from 36 primary carcinoid tumors and 5 cases of metastatic carcinoid to the liver were immunohistochemically stained for CDX2. The percent of cells with nuclear immunoreactivity and the intensity of staining were assessed. RESULTS: All 18 foregut carcinoids (10 pulmonary and 8 gastric) were negative (0%) for CDX2. All 11 midgut carcinoids (100%) were positive for CDX2 with moderate to strong staining in more than 50% of the cells. Only 2 (29%) of 7 of hindgut carcinoids were CDX2-positive with the 2 positive cases showing weak to moderate staining intensity in less than 10% of the cells. Expression of CDX2 in more than 50% of tumor cells was seen only in midgut carcinoids (P < .001). CDX2 expression in metastatic tumors was consistent with the site of origin. CONCLUSIONS: Midgut carcinoid tumors and their metastases are distinct from foregut and hindgut carcinoids in that they express high levels of CDX2. Additional studies are needed to determine whether CDX2 immunostaining may be helpful in determining the primary site of metastatic carcinoid tumors of unknown origin.

Appendiceal Neoplasms↗
PubMed2005

The CDX2 transcription factor regulates furin expression during intestinal epithelial cell differentiation.

CDX2, a member of the caudal family of transcription factors, is involved in enterocyte lineage specification. CDX2 activates many intestine-specific genes, such as sucrase-isomaltase and lactase-phlorizin hydrolase (LPH), and adhesion proteins, namely, LI-cadherin and claudin-2. In this study, we show that the proprotein convertase furin, involved in proteolytic maturation of proprotein substrates including LPH and cell surface proteins, is a CDX2 target. Indeed, expression of the rat furin homolog was induced 1.5-fold, as determined by microarray experiments that compared control with CDX2-expressing intestinal epithelial cells (IEC-6). As determined by transient transfection assays in Caco-2/15 cells, the furin P1 promoter 1.3-kb fragment between SacI and NheI was essential for CDX2 transcriptional activation. Electrophoretic mobility shift/supershift assays followed by site-specific mutagenesis and chromatin immunoprecipitation identified the CDX DNA-binding site (CBS)2 sequence from nt -1827 to -1821 as the major CBS involved in furin P1 promoter activation. Increased furin mRNA and protein expression correlated with both CDX2 expression and intestinal epithelial cell differentiation. In addition, furin mRNAs were detected predominantly in differentiated epithelial cells of the villus, as determined by in situ hybridization. Treatment of Caco-2/15 cells with a furin inhibitor led to inhibition of LPH activity. Morphological differentiation of enterocyte-like features in Caco-2/15 such as epithelial cell polarity and brush-border formation were strongly attenuated by furin inhibition. These results suggest that CDX2 regulates furin expression in intestinal epithelial cells. Furin may be important in modulating the maturation and/or activation of key factors involved in enterocyte differentiation.

Alkaline Phosphatase↗
PubMed2006

Regulation of the ovine interferon-tau gene by a blastocyst-specific transcription factor, Cdx2.

Expression of ovine interferon-tau (oIFNtau), a factor essential for the process of maternal recognition of pregnancy in ruminant ungulates, is restricted to the trophoblast. However, the molecular mechanisms by which oIFNtau expression is restricted to the trophectoderm have not been fully elucidated. The objective of this study was to determine whether oIFNtau gene transcription could be regulated through Cdx2 expression, a transcription factor implicated in the control of cell differentiation in the trophectoderm. Human choriocarcinoma JEG3 cells were co-transfected with an oIFNtau (-654 base pair, bp)-luciferase reporter (-654-oIFNtau-Luc) construct and several transcription factor expression plasmids. Compared to -654-oIFNtau-Luc alone, transcription of the -654-oIFNtau-Luc increased more than 30 times when this construct was co-transfected with Cdx2, Ets-2, and c-jun. The degree of transcription decreased to 1/4 levels when the upstream region was reduced to -551 bp, and became minimal with further deletions; this was confirmed with the use of the reporter constructs with mutated c-jun, Ets-2, and/or Cdx2 sites. In trophoblast unrelated NIH3T3 cells, which do not support IFNtau gene transcription, the oIFNtau-Luc transcription was enhanced approximately eightfold when the cells were co-transfected with the Cdx2/Ets-2 or Cdx2/Ets-2/c-jun expression plasmids. These findings were confirmed by gel-shift assays examining Cdx binding site on the oIFNtau gene's upstream region, by immunohistochemical study identifying the presence of Cdx2 in day 15 and 17 ovine conceptuses, and by Western blot detecting Cdx2 in day 17 conceptuses. Our results indicate that oIFNtau gene transcription is regulated by Cdx2, and suggest that Cdx2 could be a key molecule in determining oIFNtau gene transcription by the trophectoderm.

Animals↗
PubMed2006

The transcription factor Cdx2 regulates the intestine-specific expression of human peptide transporter 1 through functional interaction with Sp1.

H(+)/peptide cotransporter 1 (PEPT1, SLC15A1) localized at the brush-border membranes of intestinal epithelial cells plays important roles in the intestinal absorption of small peptides and a variety of peptidemimetic drugs. We previously demonstrated that transcription factor Sp1 functions as a basal transcriptional regulator of human PEPT1. However, the factor responsible for the intestine-specific expression of PEPT1 remains unknown. In the present study, we investigated the effect of the intestinal transcription factors on the transcription of the PEPT1 gene and found that only Cdx2 markedly trans-activated the PEPT1 promoter. However, the promoter region responsible for this effect lacked a typical Cdx2-binding sequence, but instead, possessed some Sp1-binding sites. In vitro experiments using Caco-2 cells showed that (1) mutation of the Sp1-binding site diminished the effect of Cdx2, (2) co-expression of Cdx2 and Sp1 synergistically trans-activated the PEPT1 promoter and (3) Sp1 protein was immunoprecipitated with Cdx2 protein. These results raise the possibility that Cdx2 modulates the PEPT1 promoter by interaction with Sp1. The significance of Cdx2 in vivo for PEPT1 regulation was shown by the determination of mRNA levels of Cdx2 and PEPT1 in human tissue. In gastric samples, some with intestinal metaplasia, the levels of PEPT1 and Cdx2 mRNA were highly correlated. Taken together, the present study suggests that Cdx2 plays a key role in the transcriptional regulation of the intestine-specific expression of PEPT1, possibly through interaction with Sp1.

Binding Sites↗
PubMed2005

The effect of cytostatic drug treatment on intestine-specific transcription factors Cdx2, GATA-4 and HNF-1alpha in mice.

Chemotherapy-induced intestinal damage is a very important dose-limiting side effect for which there is no definitive prophylaxis or treatment. This is in part due to the lack of understanding of its pathophysiology and impact on intestinal differentiation. The objective of this study was to investigate the gene expression of the small intestinal transcription factors HNF-1alpha, Cdx2, GATA-4 in an experimental model of methotrexate (MTX)-induced intestinal damage, and to correlate these alterations with histological damage, epithelial proliferation and differentiation. HNF-1alpha, Cdx2 and GATA-4 are critical transcription factors in epithelial differentiation, and in combination they act as promoting factors of the sucrase-isomaltase (SI) gene, an enterocyte-specific differentiation marker which is distinctly downregulated after MTX treatment. Mice received two doses of MTX i.v. on two consecutive days and were sacrificed 1, 3 and 7 or 9 days after final injection. Segments of the jejunum were taken for morphological, immunohistochemical and quantitative analyses. Intestinal damage was most severe at day 3 and was associated with decreased expression of the transcriptional factors HNF-1alpha, Cdx2 and GATA-4, which correlated well with decreased expression of SI, and seemed inversely correlated with enhanced proliferation of epithelial crypt cells. During severe damage, the epithelium was preferentially concerned with proliferation rather than differentiation, most likely in order to restore the small intestinal barrier function rather than maintaining its absorptive function. Since HNF-1alpha, Cdx2 and GATA-4 are critical for intestine-specific gene expression and therefore crucial in epithelial differentiation, these results may explain, at least in part, why intestinal differentiation is compromised during MTX treatment.

Animals↗
PubMed2006

Leptin transcriptionally enhances peptide transporter (hPepT1) expression and activity via the cAMP-response element-binding protein and Cdx2 transcription factors.

PepT1 is an intestinal epithelial apical membrane transporter that is expressed in the small intestine, with little or no expression in the normal colon. However, we previously demonstrated that colonic PepT1 may be expressed during chronic inflammation. To begin elucidating inflammatory hPepT1 signaling, we herein investigated the long term leptin treatments, on PepT1 expression and activity in Caco2-BBE cells, and began to reveal the involved signaling pathways. We successfully cloned the 723-bp hPepT1 promoter region and identified the human transcription initiation site 86 bp upstream from the translation start site. Leptin treatment dose- and time-dependently increased hPepT1 promoter and transport activities in Caco2-BBE cells, with maximal activity observed in cells treated with 100 nM leptin for 8 h. Under these conditions, we observed 2-fold increases in hPepT1 mRNA and protein expression, as well as increased transport activity. Our molecular analyses of possible signal-transduction pathways revealed that leptin treatment enhanced the intracellular levels of cAMP and phosphorylated cAMP-response element-binding protein (CREB) protein in Caco2-BBE cells, whereas our deletion, mutation, and CDX2 overexpression analyses demonstrated that interaction of the Cdx2 and phosphorylated CREB transcription factors was essential for leptin-induced hPepT1 transcription in Caco2-BBE cells. Our results indicate that leptin, which is increased in inflamed colonic mucosa, triggers colonic expression of hPepT1 via the CREB and Cdx2 transcription factors. These findings provide important new insights into the mechanisms of intestinal inflammation and may suggest new therapeutic modalities in the future.

5' Flanking Region↗
PubMed2002

Heparin-binding EGF-like growth factor gene transcription regulated by Cdx2 in the intestinal epithelium.

Development and differentiation of the intestinal epithelium appear to be regulated by various growth factors. Using cDNA microarrays, we identified heparin-binding EGF-like growth factor (HB-EGF) as one of the genes induced by intestinal-specific transcription factor Cdx2 in an intestinal undifferentiated rat cell line, intestinal epithelial cell (IEC)-6. Both Cdx2 and HB-EGF stimulated cell proliferation and migration, and their effects were inhibited partially by an EGF receptor-specific tyrosine kinase inhibitor, PD-153035. HB-EGF may function as one of the mediators of Cdx2 and may be associated with the proliferation and migration in the intestinal epithelium. The Cdx2 protein can bind to the Cdx2-binding element of the HB-EGF gene. Reporter gene analyses showed that the HB-EGF gene promoter is Cdx2 responsive and that the activity of the promoter in the IEC-6 cells depends on the number of consensus Cdx2-binding site-like sequences. These data indicate that HB-EGF gene expression can be regulated by Cdx2 and serves to mediate the control of Cdx2 of the proliferation and migration of IEC-6 cells.

Animals↗
PubMed2006

Human acyl-CoA:cholesterol acyltransferase 2 gene expression in intestinal Caco-2 cells and in hepatocellular carcinoma.

Humans express two ACAT (acyl-CoA:cholesterol acyltransferase) genes, ACAT1 and ACAT2. ACAT1 is ubiquitously expressed, whereas ACAT2 is primarily expressed in intestinal mucosa and plays an important role in intestinal cholesterol absorption. To investigate the molecular mechanism(s) responsible for the tissue-specific expression of ACAT2, we identified five cis-elements within the human ACAT2 promoter, four for the intestinal-specific transcription factor CDX2 (caudal type homeobox transcription factor 2), and one for the transcription factor HNF1alpha (hepatocyte nuclear factor 1alpha). Results of luciferase reporter and electrophoretic mobility shift assays show that CDX2 and HNF1alpha exert a synergistic effect, enhancing the ACAT2 promoter activity through binding to these cis-elements. In undifferentiated Caco-2 cells, the ACAT2 expression is increased when exogenous CDX2 and/or HNF1alpha are expressed by co-transfection. In differentiated Caco-2 cells, the ACAT2 expression significantly decreases when the endogenous CDX2 or HNF1alpha expression is suppressed by using RNAi (RNA interference) technology. The expression levels of CDX2, HNF1alpha, and ACAT2 are all greatly increased when the Caco-2 cells differentiate to become intestinal-like cells. These results provide a molecular mechanism for the tissue-specific expression of ACAT2 in intestine. In normal adult human liver, CDX2 expression is not detectable and the ACAT2 expression is very low. In the hepatoma cell line HepG2 the CDX2 expression is elevated, accounting for its elevated ACAT2 expression. A high percentage (seven of fourteen) of liver samples from patients affected with hepatocellular carcinoma exhibited elevated ACAT2 expression. Thus, the elevated ACAT2 expression may serve as a new biomarker for certain form(s) of hepatocellular carcinoma.

Adult↗
PubMed2000

Intestine-specific activity of the human guanylyl cyclase C promoter is regulated by Cdx2.

BACKGROUND & AIMS: The heat-stable enterotoxin receptor, guanylyl cyclase C, exhibits an intestine-specific pattern of expression. The aim of this study was to identify the transcriptional activator that mediates intestine-specific expression of guanylyl cyclase C. METHODS: Fragments of the promoter were assayed to isolate regions directing intestine-specific gene activation. Deoxyribonuclease I footprinting was used to identify a site of intestine-specific protection. Electrophoretic mobility shift assays (EMSAs) and supershift analyses were used to characterize the protein that bound to the protected site. The protected site was mutated to analyze its role in promoter activity. RESULTS: Reporter gene assays revealed that intestine-specific expression of guanylyl cyclase C is directed by the proximal promoter. Deoxyribonuclease I footprinting identified a specific site in the proximal promoter that exhibited intestine-specific protection. EMSAs and supershift analyses revealed that the transcription factor Cdx2 bound to an intestine-specific site of protection. Mutation of the Cdx2-protected site of the promoter eliminated binding of Cdx2 and reduced reporter gene activity to the level of extraintestinal cells. CONCLUSIONS: These data show that Cdx2 and its consensus-binding site in the promoter are required for intestine-specific expression of the guanylyl cyclase C gene.

CDX2 Transcription Factor↗
PubMed1999

Differentiated intestinal epithelial cells exhibit increased migration through polyamines and myosin II.

Early mucosal restitution is a rapid process by which differentiated intestinal epithelial cells migrate to reseal superficial wounds. However, most of the in vitro studies for restitution employ undifferentiated intestinal crypt cells as a model. The transcription factor, Cdx2, plays an important role in the regulation of intestinal epithelial differentiation. Forced expression of the Cdx2 gene in undifferentiated intestinal crypt cells induces the development of a differentiated phenotype. The current study was designed to determine changes in differentiated intestinal epithelial cell migration after wounding in the stable Cdx2-transfected IEC-6 cells and then to examine involvement of polyamines and nonmuscle myosin II in the process of cell motility. Cdx2-transfected IEC-6 cells were associated with a highly differentiated phenotype and exhibited increased cell migration after wounding. Migration of Cdx2-transfected IEC-6 cells were approximately four times that of nontransfected IEC-6 cells. Migration after wounding was associated with significant increases in polyamine synthesis. Depletion of cellular polyamines by 5 mM alpha-difluoromethylornithine (DFMO), a specific inhibitor of polyamine biosynthesis, inhibited cell migration without affecting the differentiated phenotype. DFMO also decreased levels of nonmuscle myosin II mRNA and protein and resulted in reorganization of myosin II, along with a marked reduction in stress fibers. Exogenous spermidine given together with DFMO not only returned nonmuscle myosin II levels and cellular distribution toward normal but also restored cell migration to control levels. These results indicate that 1) Cdx2-transfected IEC-6 cells exhibit increased cell migration after wounding and 2) cellular polyamines are absolutely required for stimulation of cell migration in association with their ability to modulate the structural organization of nonmuscle myosin II.

Animals↗
PubMed2005

Intestinal apoptotic changes linked to metabolic status in fasted and refed rats.

Intestinal apoptosis and expression of apoptosis inducers--the cytokines TNFalpha, TGFbeta1--and the intestinal transcription factor Cdx2, were studied according to two different metabolic and hormonal phases which characterize long-term fasting: the long period of protein sparing during which energy expenditure is derived from lipid oxidation (phase II), and the later phase characterized by a rise in body protein utilization and plasma corticosterone (phase III). Apoptosis was further studied in 2, 6, and 24 h refed rats. Morphological apoptotic events were observed by environmental and conventional scanning electron microscopy and a TUNEL test was used to characterize the final stages of apoptotic death. The gene and protein expressions of TNFalpha, TGFbeta1, and Cdx2 were measured. Apoptotic events and TNFalpha, TGFbeta1, and Cdx2 gene and protein expressions did not vary significantly during phase II as compared to the normally fed animals. However, a phase III fasting induced a delay in intestinal epithelial apoptosis, along with a 92, 58, and 25% decrease in TNFalpha, TGFbeta1, and Cdx2 mRNAs, respectively. The amounts of TNFalpha, TGFbeta1, and Cdx2 proteins decreased by 70, 36, and 25%, respectively. Apoptosis was restored rapidly after a 2 h refeeding following the phase III, accompanied by a significant increase in TNFalpha, TGFbeta1, and Cdx2 mRNA and the protein levels, compared to the phase III fasting values. The concomitant decreases in cytokines and Cdx2 and in apoptotic cells during phase III suggest the preservation of enterocytes during this critical fasting period in order to optimize nutrient absorption as soon as food is available and thus, to rapidly restore body mass.

Animals↗
PubMed2006

The intestine-specific homeobox gene Cdx2 induces expression of the basic helix-loop-helix transcription factor Math1.

The basic helix-loop-helix transcription factor Math1, which is transiently expressed in proliferating neural precursors in multiple domains of the developing nervous system, is also related to the cell fate decision of enteroendocrine, goblet, and Paneth cells in the intestine. On the other hand, the transcription factor Cdx2, which is normally confined to intestinal epithelial cells, is related to the differentiation of these cells. Therefore, we investigated the relationship between Math1 and Cdx2 in intestinal epithelial cells. The Math1 and Cdx2 expressions in normal intestinal mucosa and intestinal metaplastic mucosa from mouse and human stomachs, as well as an intestinal crypt-derived cell line, were analyzed by immunohistochemistry, reverse transcription-polymerase chain reaction and Northern blotting, and Math1 enhancer element was analyzed by luciferase reporter assays. Math1-positive epithelial cells co-expressing Cdx2 were found in normal intestinal mucosa from humans and mice. Furthermore, Math1-producing epithelial cells that showed positive immunostaining for Cdx2 were also observed in intestinal metaplastic mucosa from human and Cdx2 transgenic mouse stomachs, although they were not detected in normal gastric mucosa of humans and mice. Expression of Cdx2 stimulated endogenous Math1 mRNA expression in the intestinal crypt-derived cell line IEC-6, corroborating observations in Cdx2-expressing intestinal metaplastic mucosa. Furthermore, expression of Cdx2 in IEC-6 cells conferred the ability to express a Math1 reporter gene containing a Math1 enhancer. Based on these results, we hypothesize that Cdx2 is involved in activating Math1 expression in intestinal epithelial cells.

Animals↗
PubMed2003

CDX2, a homeobox transcription factor, upregulates transcription of the p21/WAF1/CIP1 gene.

The CDX2 homeobox transcription factor plays key roles in intestinal development and homeostasis. CDX2 is downregulated during colorectal carcinogenesis, whereas overexpression of CDX2 results in growth inhibition and differentiation of colon carcinoma and intestinal cells. However, the means by which CDX2 functions remain poorly understood. p21/WAF1/CIP1 is one of the cyclin-dependent kinase inhibitors. In addition to its role in cell cycle control, p21 plays critical roles in differentiation and tumor suppression. The overlapping in both the expression and function of CDX2 and p21 in the small intestine and colon strongly suggests a link between these two genes. By means of luciferase reporter and electrophoretic mobility shift assays, we show here that CDX2 transactivated and physically interacted with the promoter of p21 in a p53-independent manner. Moreover, overexpression of CDX2 increased the mRNA expression of p21 in HT-29 colon carcinoma cells, as demonstrated by reverse transcription-polymerase chain reaction. These data suggest that p21 is a transcriptional target of CDX2. Our results may thus provide a new mechanism underlying the functions of CDX2.

Animals↗
PubMed2003

Expression of the intestine-specific transcription factors, Cdx1 and Cdx2, correlates shift to an intestinal phenotype in gastric cancer cells.

PURPOSE: It is well known that gastric cancers (GCs) at early stages, independent of the histological type, mainly consist of gastric phenotype malignant cells, while those at advanced stage tend to have a more intestinal phenotype with progression. However, the connection between this shift and expression of homeobox genes, which are important factors to maintain tissue character, has remained unclear. We therefore evaluated the expression of Cdx1/2 in relation to the phenotype of GCs. METHODS: We analyzed the expression of Cdx1/2 mRNAs by Northern blotting and Cdx2 protein by immunohistochemistry in seventy advanced GCs, and evaluated phenotypically using mucin- and immunohistochemistry. RESULTS: Seventy GCs were divided phenotypically into 16 gastric (G type), 18 gastric and intestinal mixed (GI type), 18 intestinal (I type), and 18 null (N type) phenotypes, independent of the histological classification. Cdx1 and Cdx2 mRNAs statistically demonstrated an increase with shift from G to I ( P=0.042 and P=0.0082, respectively). Cdx2 nuclear staining was observed immunohistochemically in the intestinal phenotypic cancer cells, but could not be detected in those with only the gastric phenotype. CONCLUSIONS: These results show that Cdx1 and Cdx2 might be indispensable for intestinal phenotypic expression even in gastric cancer cells.

Biomarkers, Tumor↗