Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Wnt signaling, beta-catenin and plakoglobin transduce signals to the nucleus through interactions with TCF-type transcription factors. However, when plakoglobin is artificially engineered to restrict it to the cytoplasm by fusion with the transmembrane domain of connexin (cnxPg), it efficiently induces a Wnt-like axis duplication phenotype in Xenopus. In Xenopus embryos, maternal XTCF3 normally represses ventral expression of the dorsalizing gene Siamois. Two models have been proposed to explain the Wnt-like activity of cnxPg: 1) that cnxPg inhibits the machinery involved in the turnover of cytosolic beta-catenin, which then accumulates and inhibits maternal XTCF3, and 2) that cnxPg directly acts to inhibit XTCF3 activity. To distinguish between these models, we created a series of N-terminal deletion mutations of cnxPg and examined their ability to induce an ectopic axis in Xenopus, activate a TCF-responsive reporter (OT), stabilize beta-catenin, and colocalize with components of the Wnt signaling pathway. cnxPg does not colocalize with the Wnt pathway component Dishevelled, but it does lead to the redistribution of APC and Axin, two proteins involved in the regulation of beta-catenin turnover. Expression of cnxPg increases levels of cytosolic beta-catenin; however, this effect does not completely explain its signaling activity. Although cnxPg and Wnt-1 stabilize beta-catenin to similar extents, cnxPg activates OT to 10- to 20-fold higher levels than Wnt-1. Moreover, although LEF1 and TCF4 synergize with beta-catenin and plakoglobin to activate OT, both suppress the signaling activity of cnxPg. In contrast, XTCF3 suppresses the signaling activity of both beta-catenin and cnxPg. Both exogenous XLEF1 and XTCF3 are sequestered in the cytoplasm of Xenopus cells by cnxPg. Based on these data, we conclude that, in addition to its effects on beta-catenin, cnxPg interacts with other components of the Wnt pathway, perhaps TCFs, and that these interactions contribute to its signaling activity.
 ...
PMID:Membrane-anchored plakoglobins have multiple mechanisms of action in Wnt signaling. 1051 57

beta-catenin was shown to be a major oncoprotein in colon cancer development. Its oncogenic function as a transcriptional activator is upregulated by mutations in the APC tumor suppressor gene, leading to a constitutive activation of the proliferation-associated genes c-myc and cyclin D. The aim of this study was to demonstrate a role of APC-mutations and dysregulated beta-catenin also for the progression of colorectal cancer, by identifying new target genes of beta-catenin associated with tumor invasion and metastasis. Potential invasion genes regulated by beta-catenin and its DNA binding partner TCF4 were identified by a computer search for the consensus DNA binding sequence in relevant promoter regions. Specific DNA binding was confirmed by gel shift assays. Functional importance of beta-catenin for the activation of identified genes was determined by luciferase reporter assays. The significance was demonstrated by coexpression of nuclear beta-catenin and the identified target genes by immunohistochemistry. Among other invasion genes, we identified the matrix metallo proteinases MMP-7 and MMP-1 activated by beta-catenin in the tumor cells. MMP-7 is an important factor for invasion and metastasis and overexpressed in 75% of colon carcinomas. The significance for human colon cancer development was demonstrated by a correlated overexpression of beta-catenin and the MMPs, beginning in large, severely dysplastic adenomas. Our results explain the high percentage of MMP-7 overexpression in colorectal tumors and the resulting activation of invasive growth. Moreover by identifying dysregulated beta-catenin as a transcriptional activator of MMPs and other invasion factors, we demonstrated an important role of mutated APC not only for early steps but also for the progression of colorectal carcinogenesis.
 ...
PMID:[beta-Catenin induces invasive growth by activating matrix metalloproteinases in colorectal carcinoma]. 1121 38

The development of intestinal cancer involves complex genetic and epigenetic alterations in the intestinal mucosa. The principal signaling pathway responsible for the initiation of tumor formation, the APC-beta-catenin-TCF4 pathway, regulates both cell proliferation and colonic cell differentiation, but many other intrinsic and extrinsic signals also modulate these cell maturation pathways. The challenge is to understand how signaling and cell maturation are also modulated by nutritional agents. Through gene expression profiling, we have gained insight into the mechanisms by which short chain fatty acids regulate these pathways and the differences in response of gene programs, and of the specific regulation of the c-myc gene, to physiological regulators of intestinal cell maturation, such as butyrate, compared with pharmacological regulators such as the nonsteroidal antiinflammatory drug sulindac. Moreover, we used a combination of gene expression profiling of the response of cells in culture to sulindac and the response of the human mucosa in subjects treated with sulindac for 1 month, coupled with a mouse genetic model approach, to identify the cyclin dependent kinase inhibitor p21(WAF1/Cip1) as an important suppressor of Apc-initiated intestinal tumor formation and a necessary component for tumor inhibition by sulindac. Finally, the mucous barrier, secreted by intestinal goblet cells, is the interface between the luminal contents and the intestinal mucosa. We generated a mouse genetic model with a targeted inactivation of the Muc2 gene that encodes the major intestinal mucin. These mice have no recognizable goblet cells due to the failure of cells to synthesize and store mucin. This leads to perturbations in intestinal crypt architecture, increased cellular proliferation and rates of cell migration, decreased apoptosis and development of adenomas and adenocarcinomas in the small and large intestine and the rectum.
 ...
PMID:Short chain fatty acids and colon cancer. 1246 28

The structural maintenance of chromosome protein SMC3 is a component of the cohesin complex that mediates sister chromatid cohesion and segregation in prokaryotes and eukaryotes. It is also present extracellularly in the form of a chondroitin sulfate proteoglycan known as bamacan. We have found previously that SMC3 expression is elevated in a large fraction of human colon carcinomas. The additional finding that the protein is significantly increased in the intestinal polyps of ApcMin/+ mice has led us to hypothesize that SMC3 expression is linked to activation of the APC/beta-catenin/TCF4 pathway. The immunohistochemical analysis of colon adenocarcinomas from clinical specimens revealed that beta-catenin and SMC3 antigens co-localize with maximal stain intensity within the transformed areas. Cloning and sequencing of 1578 bp of the human SMC3 promoter unveiled the presence of seven putative consensus sequences for beta-catenin/TCF4 binding, two of which are conserved in the mouse Smc3 promoter. Transient transfection experiments in HCT116 and SW480 human colon carcinoma cells using deletion and mutated promoter constructs in luciferase reporter vectors confirmed that the putative sites, the first located at -48 bp and the second located at -701 bp, are susceptible to beta-catenin/TCF4 transactivation. Co-transfection with a beta-catenin expression vector enhanced the promoter activity whereas E-cadherin had the opposite effect. Binding of beta-catenin/TCF4 complexes from SW480 nuclear extracts to these sequences was confirmed by electrophoretic shift and supershift mobility assays. Altogether these results are consistent with the idea that the beta-catenin/TCF4 transactivation pathway contributes to SMC3 overexpression in intestinal tumorigenesis.
 ...
PMID:The cohesin SMC3 is a target the for beta-catenin/TCF4 transactivation pathway. 1265 60

Mullerian inhibiting substance type II receptor (MISRII) is a member of the transforming growth factor-beta superfamily. Mutations in mullerian inhibiting substance (MIS) or MISRII cause male sexual abnormalities, persistent mullerian duct syndrome, and pseudohermaphroditism. The spatial and temporal regulation of MIS and MISRII is important for its biological action. Male Wnt7a mutant mice do not undergo regression of mullerian ducts. Here we showed that the canonical Wnt signaling pathway regulated MISRII. The promoter MISRII was activated by beta-catenin expression, and this activation was dependent on TCF4-binding sites. The nuclear receptor superfamily member steroidogenic factor 1 (SF1) synergistically activated the MISRII promoter with beta-catenin. APC, a negative regulator of Wnt signaling, decreased SF1-mediated activation of the MISRII promoter in the colon carcinoma cell line SW480. We also showed a direct physical interaction between beta-catenin and SF1 by co-immunoprecipitation. Thus, our findings suggest that MISRII is a developmental target of Wnt7a signaling for mullerian duct regression during sexual differentiation.
 ...
PMID:Synergistic cooperation between the beta-catenin signaling pathway and steroidogenic factor 1 in the activation of the Mullerian inhibiting substance type II receptor. 1272 25

In human genetics and molecular oncology, mutation research is necessary not only to identify mutations in nucleic acid sequences, but also to analyze the loss of function caused by mutant proteins. We reconstructed a protein-protein network system of human beta-catenin and TCF4, in Saccharomyces cerevisiae. beta-Catenin and TCF4 proteins form a complex and transactivate reporter genes. Co-expressed wild-type APC with beta-catenin and TCF4 inhibit the transcriptional activity of the beta-catenin/TCF4 complex in yeast, as well as in mammals. This unique method in which the beta-catenin/TCF4 signaling pathway is reconstructed in vivo may prove useful for the functional evaluation of APC mutants, including a type of APC truncated and missense mutants influenced to the ability of binding to beta-catenin.
 ...
PMID:Reconstructed beta-catenin/TCF4 signaling in yeast applicable to functional evaluation of APC mutations. 1463 95

In order to understand the role of mismatch repair (MMR) gene in colorectal carcinogenesis,microsatellite instability (MSI) status of 16 microsatellite loci of 62 adenomas from 59 patients, including sporadic and familial adeonmatous polyposis (FAP) adenomas were detected by microdissection-PCR-SSLP, and protein expressions of beta-catenin, P53, and BAX, etc. were assayed by immunohistochemistry. Results were as following: (1)The overall MSI alteration rate of the 16 loci was 14.4%. Different adenomas from the same patient showed different microsatellite alterations at the same loci; (2)All of the five FAP patients were MSI-L, three of which showed MSI at the locus of hMSH3; (3)The membrane expression rate of beta-catenin in adenomas and accompanied carcinomas was 42.9% and 11.4%, respectively (P<0.001); (4)Microsatellite alterations of the microsatellite loci of TP53, D5S346, TCF4(A)(9), TGFbetaRII(GT)(3) and TGFbetaRII(A)(10) were associated with the changes of their protein expressions. It could be concluded the following: (1)Microsatellite instability existed even in the early stage (adenomas) of colorectal tumorigenesis. The alterations of chromosome 1p, APC genes, and the TGFbeta signal transduction pathway could also be deduced; (2)In the progression of adenoma to carcinoma, the staining of beta-catenin would be transferred from membrane to cytoplasm and then nucleus, and the cytoplasm stain was stronger in carcinoma than that in adenomas. The abnormality of the signal transduction pathway of APC-beta-catenin-TCF4 could be concluded.
 ...
PMID:[Microsatellite instability and relative gene expressions in sporadic and familial adenomatous polyposis adenomas]. 1562 58

An unselected series of 310 colorectal carcinomas, stratified according to microsatellite instability (MSI) and DNA ploidy, was examined for mutations and/or promoter hypermethylation of five components of the WNT signaling cascade [APC, CTNNB1 (encoding beta-catenin), AXIN2, TCF4, and WISP3] and three genes indirectly affecting this pathway [CDH1 (encoding E-cadherin), PTEN, and TP53]. APC and TP53 mutations were each present more often in microsatellite-stable (MSS) tumors than in those with MSI (P < .001 for both). We confirmed that the aneuploid MSS tumors frequently contained TP53 mutations (P < .001), whereas tumors with APC mutations and/or promoter hypermethylation revealed no associations to ploidy. Mutations in APC upstream of codons 1020 to 1169, encoding the beta-catenin binding site, were found in 15/144 mutated tumors and these patients seemed to have poor clinical outcome (P = .096). Frameshift mutations in AXIN2, PTEN, TCF4, and WISP3 were found in 20%, 17%, 46%, and 28% of the MSI tumors, respectively. More than half of the tumors with heterozygote mutations in AXIN2 were concurrently mutated in APC. The present study showed that more than 90% of all samples had alteration in one or more of the genes investigated, adding further evidence to the vital importance of activated WNT signaling in colorectal carcinogenesis.
 ...
PMID:Genetic and epigenetic changes of components affecting the WNT pathway in colorectal carcinomas stratified by microsatellite instability. 1580 15

It has been hypothesized that dietary conjugated linoleic acids (CLA) may inhibit colon tumorigenesis. The aim of our study was to investigate the cellular and molecular effects of cis-9 (9Z), trans-11 (11E)-CLA on the proliferation, differentiation, interaction with peroxisome proliferator-activated receptors (PPARs), and expression of genes relevant in the APC-beta-catenin-TCF4 signalling pathway in human HT-29 and Caco-2 colon cells. We found that 9Z,11E-CLA inhibited the proliferation of HT-29 and Caco-2 cells. Trans-vaccenic acid (VA) showed no antiproliferative effects at all. We determined that 9Z,11E-CLA induced cell differentiation as measured by intestinal alkaline phosphatase (IAP) enzyme activity in Caco-2 cells, mRNA expression of IAP, and activation of a 5' flanking region of IAP. The 9Z,11E-CLA activated human PPARdelta as measured in a reporter gene assay. Treatment of HT29 cells in the poliferation phase with 9Z,11E-CLA repressed mRNA-expression of proliferation genes such as c-myc, cyclin D1 and c-jun in a concentration dependent manner. The promoter activities of c-myc and AP1 were also inhibited after incubation with 9Z,11E-CLA. beta-Catenin mRNA and protein expression was also repressed by the treatment with 9Z,11E-CLA. In addition, the mRNA expression of PPARdelta was repressed by treatment of the HT-29 cells with 9Z,11E-CLA. We conclude that 9Z,11E-CLA has an antiproliferative effect at the cellular and molecular levels in human colon cells. The results indicate that the preventive effects of CLA in the development of colon cancer may be due to their downregulation of some target genes of the APC-beta-catenin-TCF-4- and PPARdelta signalling pathway.
 ...
PMID:Molecular and cellular effects of cis-9, trans-11-conjugated linoleic acid in enterocytes: effects on proliferation, differentiation, and gene expression. 1593 29

The proto-oncoprotein c-Jun is a component of the AP-1 transcription factor, the activity of which is augmented in many tumour types. An important mechanism in the stimulation of AP-1 function is amino-terminal phosphorylation of c-Jun by the c-Jun N-terminal kinases (JNKs). Phosphorylated c-Jun is biologically more active, partially because it acquires the ability to interact with binding partners. Here we show that phosphorylated c-Jun interacts with the HMG-box transcription factor TCF4 to form a ternary complex containing c-Jun, TCF4 and beta-catenin. Chromatin immunoprecipitation assays revealed JNK-dependent c-Jun-TCF4 interaction on the c-jun promoter, and c-Jun and TCF4 cooperatively activated the c-jun promoter in reporter assays in a beta-catenin-dependent manner. In the Apc(Min) mouse model of intestinal cancer, genetic abrogation of c-Jun N-terminal phosphorylation or gut-specific conditional c-jun inactivation reduced tumour number and size and prolonged lifespan. Therefore, the phosphorylation-dependent interaction between c-Jun and TCF4 regulates intestinal tumorigenesis by integrating JNK and APC/beta-catenin, two distinct pathways activated by WNT signalling.
 ...
PMID:Interaction of phosphorylated c-Jun with TCF4 regulates intestinal cancer development. 1600 74


1 2 3 Next >>