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

Large deletions in the APC (adenomatous polyposis coli) gene, causing familial adenomatous polyposis (FAP), cannot easily be detected by conventional mutation-detection techniques. Therefore, we have developed two independent quantitative methods for the detection of large deletions, encompassing one or more exons, of APC. Multiplex ligation-dependent probe amplification (MLPA) is performed in one reaction for the initial quantification of all APC exon copy numbers. Subsequently, quantitative real-time PCR (QRT-PCR) is used to verify the results obtained in the MLPA reaction. The identification of a deletion of the whole APC gene in a patient with classical FAP is described. The mutation was detected with the two quantitative methods and further verified on chromosomal level by the use of FISH (fluorescence in situ hybridization) on metaphase spreads. Furthermore, a large deletion covering exons 11-13 of the APC gene was detected in two apparently unrelated families. This deletion was further verified and characterized with long-range PCR. The MLPA test ensures a sensitive high-throughput screening for large deletions of the APC gene and can easily be implemented in the diagnostic testing for FAP.
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PMID:Identification of genomic deletions of the APC gene in familial adenomatous polyposis by two independent quantitative techniques. 1572 47

Deregulated activation of the canonical Wnt signalling pathway leads to stabilization of beta-catenin and is critically involved in carcinogenesis by an inappropriate induction of lymphocyte enhancer factor (LEF-1)/beta-catenin-dependent transcription of Wnt target genes. Phosphorylation of the pathway components beta-catenin, Dishevelled, Axin and APC (adenomatous polyposis coli) by glycogen synthase kinase-3beta, CK1 and CK2 is of central importance in the regulation of the beta-catenin destruction complex. Here, we identify CK1 and CK2 as major kinases that directly bind to and phosphorylate LEF-1 inducing distinct, kinase-specific changes in the LEF-1/DNA complex. Moreover, CK1-dependent phosphorylation in contrast to CK2 disrupts the association of beta-catenin and LEF-1 but does not impair DNA binding of LEF-1. Sequential phosphorylation assays revealed that for efficient disruption of the LEF-1/beta-catenin complex, beta-catenin also has to be phosphorylated. Consistent with these observations, CK1-dependent phosphorylation inhibits, whereas CK2 activates LEF-1/beta-catenin transcriptional activity in reporter gene assays. These data are in line with a negative regulatory function of CK1 in the Wnt signalling pathway, where CK1 in addition to the beta-catenin destruction complex at a second level acts as a negative regulator of the LEF-1/beta-catenin transcription complex, thereby protecting cells from development of cancer.
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PMID:A second protein kinase CK1-mediated step negatively regulates Wnt signalling by disrupting the lymphocyte enhancer factor-1/beta-catenin complex. 1574 65

The adenomatous polyposis coli gene (APC gene) originally was identified as a tumor suppressor gene in colon cancer. We reported previously that APC is mutated and/or deleted in primary oral squamous cell carcinoma (OSCC) tissues and suggested that loss of APC function contributes to carcinogenesis in the oral region. In this study, we examined 50 OSCC tissue samples, which had been fixed in 10% buffered formaldehyde solution and embedded in paraffin, and eight cell lines, which were derived from OSCC, to analyze the expression level of the APC gene. Significant down-regulation of APC was detected by immunohistochemistry in 15 (30.0%) of 50 tissue samples and by the reverse transcriptase-polymerase chain reaction in five (62.5%) of eight cell lines. We then investigated the status of APC gene promoter methylation and restoration of the APC gene mRNA. Hypermethylation of the APC promoter CpG island was detected in two of eight (25%) OSCC-derived cell lines, and APC gene mRNA was restored in all OSCC-derived cell lines showing down-regulation of gene expression (n=5) after treatment with 5-aza-2'-deoxycytidine, a DNA demethylating agent. Thus, the contribution of down-regulated APC expression to the development of human OSCC was about 30%, and hypermethylation of the gene promoter CpG island was confirmed to be a significant mechanism of inactivation of the APC gene in oral carcinogenesis.
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PMID:Status of reduced expression and hypermethylation of the APC tumor suppressor gene in human oral squamous cell carcinoma. 1575 20

Colorectal cancer CRC is one of the most common malignancies worldwide. Advances in molecular techniques have provided deep insight into the molecular pathogenesis, biologic and genetic changes occurring in colon cancer patients. Current theories of malignant transformation postulate that development of colon cancer is related to 2 main pathways; the loss of heterozygosity pathway, which is usually due to a defect in the adenomatous polyposis coli APC gene and microsatellite instability, which is usually due to a defect in mismatch repair MMR genes. This review summarizes the role of the wingless signaling pathway genes including APC and MMR genes in the development of CRC.
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PMID:Wingless signaling pathway family relation to colon cancer. Have we come full circle? 1575 47

The use of mouse models to study neoplasia is proving particularly powerful in dissecting the mechanisms underlying disease initiation and progression. However, the majority of these models have been somewhat limited in studying the very early effects of loss of gene function, as tumour initiation relies upon either constitutive loss of gene function or spontaneous somatic loss of function. We have therefore adopted a strategy of using an inducible Cre-lox-based system to analyse the effects of loss of gene function, the use of which is reviewed here for the intestinal tumour suppressor APC (adenomatous polyposis coli). Using this approach, we have conditionally and synchronously inactivated APC in virtually all the epithelial cells of the adult murine small intestine. After 5 days following induction of Cre-mediated recombination, mice show grossly altered crypt/villus architecture. Deficiency in APC perturbs migration, alters the normal programme of differentiation and results in increased proliferation and apoptosis. Microarray analysis reveals the transcriptome to be significantly altered; reflecting both gross phenotypic changes and changes in transcriptional activation. These findings demonstrate that APC is indeed the critical determinant of cell fate in the intestinal epithelium, explaining its role as the cellular 'gatekeeper' in preventing neoplasia.
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PMID:Studying the consequences of immediate loss of gene function in the intestine: APC. 1604 69

Colorectal cancer (CRC) is the second largest cause of cancer-related deaths in Western countries. CRC arises from the colorectal epithelium as a result of the accumulation of genetic alterations in defined oncogenes and tumour suppressor genes. Mutations in the tumour suppressor APC (adenomatous polyposis coli) genes occur early in the development of CRC and lead to the stabilization of the Wnt pathway component beta-catenin and to the constitutive activation of Wnt signalling. Stabilizing mutations of beta-catenin can also lead to its accumulation, qualifying beta-catenin as a proto-oncogene. Here I will summarize the biochemical interactions occurring in Wnt signalling and describe how alterations in Wnt pathway components lead to CRC.
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PMID:The role of the Wnt signalling pathway in colorectal tumorigenesis. 1604 71

A unique feature of colon cancer is that truncation mutations in the APC (adenomatous polyposis coli) gene are common to most tumours. The high penetrance of APC mutations, especially in gut epithelium, supports the idea that APC may be involved in a number of the processes that govern the normal maintenance of this tissue: differentiation, migration, proliferation and apoptosis. Indeed, APC is involved in the regulation of beta-catenin and it also is an important regulator of the cytoskeleton. Thus mutations in APC lead to the accumulation of beta-catenin, which causes changes in differentiation, and they also produce changes in cytoskeletal organization, which results in altered cell migration and disrupted mitotic spindles. The function of APC in cytoskeletal organization is related to its effect on microtubules and F-actin. Depleting APC from cultured cells leads to changes in cytoskeletal organization. In addition, N-terminal fragments of APC, like those commonly found in tumours, compromise cell migration in Dictyostelium and in early developing chicken embryos. Consistent with the idea that such dominant effects are normally balanced by interactions within the full-length molecule, protein interactions of N-terminal fragments expressed in tumour cells can be altered by binding to C-terminal regions of APC commonly lost in tumours. This review summarizes effects of APC on the cytoskeleton and discusses how these functions of APC may contribute to its role in cancer.
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PMID:Relationship between the role of the adenomatous polyposis coli protein in colon cancer and its contribution to cytoskeletal regulation. 1604 76

The analysis of APC and MYH mutations in adenomatous polyposis coli patients should provide clues about the genetic heterogeneity of the syndrome in human populations. The entire coding region and intron-exon borders of the APC and MYH genes were analyzed in 60 unrelated Italian adenomatous polyposis coli patients. APC analysis revealed 26 point mutations leading to premature termination, one missense variant and one deletion spanning the entire coding region in 32 unrelated patients. Novel truncating point mutations included c.1176_1177insT (p.His393_PhefsX396), c.1354_1355del (p.Val452_SerfsX458), c.2684C>A (p.Ser895X), c.2711_2712del (p.Arg904_LysfsX910), c.2758_2759del (p.Asp920_CysfsX922), c.4192_4193del (p.Ser1398_SerfsX1407), c.4717G>T (p.Glu1573X) and a novel cryptic APC exon 6 splice site. MYH analysis revealed nine different germline variants in nine patients, of whom five were homozygotes or compound heterozygotes. The mutations included 4 novel MYH missense variants (c.692G>A, p.Arg231His; c.778C>T, p.Arg260Trp; c.1121T>C, p.Leu374Pro; and c.1234C>T, p.Arg412Cys) affecting conserved amino acid residues in the ENDO3c or NUDIX domains of the protein and one novel synonymous change (c.672C>T, p.Asn224Asn). Genotype-phenotype correlations were found in carriers of APC mutations but not in carriers of biallelic MYH mutations, except for a negative correlation with low number of polyps. A distinctive characteristic of patients negative for APC and MYH mutations was a significantly (p<0.0001) older age at diagnosis compared to patients with APC mutations. Moreover, the proportion of cases with an attenuated polyposis phenotype was higher (p = 0.0008) among patients negative for APC and MYH mutations than among carriers of APC or biallelic MYH mutations.
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PMID:Mutations of APC and MYH in unrelated Italian patients with adenomatous polyposis coli. 1613 47

The association of specific genetic disturbances with the development of hereditary cancer helps us to understand the risk of suffering from it, the possibility of an earlier diagnosis, and the treatment and prevention of this disease. Familial adenomatous polyposis (FAP) is a pre-neoplastic syndrome characterized by the presence of hundreds of adenomatous polyps in the colon, which develop into a carcinoma. FAP can be diagnosed using sequencing techniques to detect mutations in the germinal line of the APC (adenomatous polyposis coli) gene. The genetic diagnostic approach in families with FAP, previously followed up in the Gastrointestinal Clinic, has both advantages and disadvantages, and places us nearer the disease and patient. Disclosing the results of this genetic test entails relevant problems in clinical practice, which affect the health field and raise legal and ethical issues, along with the familial, occupational, and social implications that knowing the genetic status can have on the patient. Genetic analysis is rare in normal clinical practice, which involves errors in the interpretation of the results obtained, and during the process of genetic counselling. Specialized multidisciplinary units are necessary for the management of patients with FAP undergoing analysis and appropriate genetic counselling, thus providing an individualized service. The creation of FAP registers and protocols for this healthcare process should optimize the management of these patients and their families.
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PMID:Clinical and ethical implications of genetic counselling in familial adenomatous polyposis. 1626 38

Alterations in the Wnt/APC (adenomatous polyposis coli) signalling pathway, resulting in beta-catenin/T cell factor (Tcf)-dependent transcriptional gene activation, are frequently detected in familial and sporadic colon cancers. The neuropeptide neurotensin (NT) is widely distributed in the gastrointestinal tract. Its proliferative and survival effects are mediated by a G-protein coupled receptor, the NT1 receptor. NT1 receptor is not expressed in normal colon epithelial cells, but is over expressed in a number of cancer cells and tissues suggesting a link to the outgrowth of human colon cancer. Our results demonstrate that the upregulation of NT1 receptor occurring in colon cancer is the result of Wnt/APC signalling pathway activation. We first established the functionality of the Tcf response element within the NT1 receptor promoter. Consequently, we observed the activation of NT1 receptor gene by agents causing beta-catenin cytosolic accumulation, as well as a strong decline of endogenous receptor when wt-APC was restored. At the cellular level, the re-establishment of wt-APC phenotype resulted in the impaired functionality of NT1 receptor, like the breakdown in NT-induced intracellular calcium mobilization and the loss of NT pro-invasive effect. We corroborated the Wnt/APC signalling pathway on the NT1 receptor promoter activation with human colon carcinogenesis, and showed that NT1 receptor gene activation was perfectly correlated with nuclear or cytoplasmic beta-catenin localization while NT1 receptor was absent when beta-catenin was localized at the cell-cell junction in early adenomas of patients with familial adenomatous polyposis, hereditary non-polyposis colorectal cancer and loss of heterozygosity tumours. In this report we establish a novel link in vitro between the Tcf/beta-catenin pathway and NT1 receptor promoter activation.
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PMID:Neurotensin receptor 1 gene activation by the Tcf/beta-catenin pathway is an early event in human colonic adenomas. 1629 83


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