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PubMed2001

Cold single-strand conformation polymorphism analysis: optimization for detection of APC gene mutations in patients with familial adenomatous polyposis.

Over 200 adenomatous polyposis coli (APC) gene mutations have been described in familial adenomatous polyposis (FAP) patients. Recent single-strand conformation polymorphism (SSCP) screening methods have introduced minigel runs, simple ethidium bromide staining and external temperature control without any loss of sensitivity (cold-SSCP). In order to test the effectiveness in APC mutation detection, cold-SSCP was employed following polymerase chain reaction (PCR) amplification in three patients with FAP. Different running parameter combinations were compared. The three mutations already known were all diagnosed by cold-SSCP. The gel concentration was found to be essential in detecting the single-base substitution in fragments of different lengths. The observation of deletions was not affected by gel concentrations and heteroduplex bands were always produced. The temperature or glycerol addition did not significantly affect sensitivity. This modified cold-SSCP method provides a simple and effective way for detecting several known Apc gene mutations without any loss of sensitivity and could be useful for large-scale molecular diagnosis of FAP.

Adenomatous Polyposis Coli↗

PubMed1992

Loss of normal allele of the APC gene in an adrenocortical carcinoma from a patient with familial adenomatous polyposis.

Endocrine neoplasms have been reported occasionally in patients with familial adenomatous polyposis (FAP). An adrenocorotical carcinoma was studied in a patient with a family history of FAP. Loss of heterozygosity (LOH) in the region close to the adenomatous polyposis coli (APC) gene was detected in this carcinoma, and evidence was obtained that there was a loss of the normal allele of the APC gene. This is the first demonstration of LOH at the APC locus in adrenocortical tumors. The present results and our previous data on LOH in a recurring desmoid tumor suggest that the heterozygous mutant/wild-type condition of the APC gene may give rise to benign tumors, and that functional loss of this gene leads to development of tumors not only in the colon but also in other various parts of the body in FAP patients.

Adenomatous Polyposis Coli↗

PubMed2000

Mutational analysis of the CTNNB1 and APC genes in uterine endometrioid carcinoma.

Despite recent studies, the molecular genetic events responsible for the development of uterine endometrioid carcinoma (UEC) remain incompletely characterized. Mutations in the beta-catenin (CTNNB1) gene have been recently reported in a small percentage of UECs and in the endometrioid variant of ovarian carcinoma suggesting that the Wnt signal transduction pathway is involved in the development of female genital tract tumors with endometrioid morphology. The Wnt pathway is a critical pathway in the development of colorectal cancer (CRC) with mutations occurring in the beta-catenin (CTNNB1) or adenomatous polyposis coli (APC) genes in 10 to 15% and 85% of cases, respectively. Because UEC and CRC share other molecular genetic alterations and histologic features and previous studies of UEC have not reported an analysis of the APC gene, we chose to further elucidate the role of the Wnt pathway in UEC. To this end, we analyzed 32 cases of UEC for mutations of the CTNNB1 and APC genes. Mutations of CTNNB1 were present in six of 32 (18%) cases: four grade 1 carcinomas, one grade 2, and one grade 3 carcinoma. Five missense mutations were identified, three involving Ser/Thr phosphorylation sites and two adjacent to a Ser phosphorylation site. One case contained a deletion encompassing codons 34 to 37, which includes a Ser phosphorylation site. No mutations resulting in truncation of the APC protein were found. Our results support a role for the Wnt signaling pathway via mutation of CTNNB1, but not APC, in the development of a subset of UECs.

Blotting, Western↗

PubMed2006

Mutational analysis of the APC gene in cribriform-morula variant of papillary thyroid carcinoma.

INTRODUCTION: Familial adenomatous polyposis (FAP) is an inherited autosomal dominant syndrome caused by germline mutations in the adenomatous polyposis coli (APC) gene. Papillary thyroid cancer is one of the extracolonic manifestations of FAP. A characteristic histologic feature of this type of thyroid tumor is the cribriform-morula variant of papillary thyroid carcinoma (CMVPTC). METHODS: To investigate roles of the APC and beta-catenin genes in the development of CMVPTC, we examined germline and somatic mutations of these genes in a female patient with CMVPTC and FAP. The patient had undergone total colectomy at the age of 19 years and total thyroidectomy at age 25 years. RESULTS: Numerous tumors were disseminated in both lobes of the thyroid gland, and histopathologic examination revealed typical CMVPTC. DNA was extracted from peripheral blood leukocytes and 12 CMVPTC tumors, and exons 1-15 of the APC gene and exon 3 of the beta-catenin gene were examined. A germline mutation was detected in exon 13 of the APC gene, and this mutation generated a premature stop codon. Six somatic mutations (922delC, 1602delA, 1821delT, 1920delG, 2706del20, 2804insA) were found in the CMVPTC specimens. All mutations were truncating mutations in the N-terminus of the APC protein. Loss of heterozygosity was not observed in the remaining tumor tissues without somatic APC mutations. There were no mutations of the beta-catenin gene in peripheral blood leukocytes or 12 CMVPTC specimens. CONCLUSIONS: These results suggest that APC mutations play an important role in the development of CMVPTC and occur predominantly in the 5' side of the APC gene between codons 308 and 935.

Adenocarcinoma, Papillary↗

PubMed1992

The APC gene, responsible for familial adenomatous polyposis, is mutated in human gastric cancer.

Although gastric cancer is the most common cancer in the world, genetic changes during its carcinogenesis are not well understood. Since some gastric cancers are considered to originate from the intestinal metaplasia, it is likely that the adenomatous polyposis coli (APC) gene, the mutation of which causes adenomatous polyps in the colon, is associated with carcinogenesis of gastric cancer. Based on this idea, DNAs isolated from gastric cancers were examined by means of a RNase protection analysis coupled with polymerase chain reaction followed by sequencing of the polymerase chain reaction products. By screening nearly one-half of the coding region of the APC gene in 44 tumors, somatic mutations were detected in three tumors: a missense mutation, a nonsense mutation, and a 5-base pair deletion resulting in a frame shift which causes truncation of the gene product. These results suggest that the mutation of the APC gene also plays an important role during the carcinogenesis of at least some gastric cancers.

Adenocarcinoma↗

PubMed2006

[A novel APC gene germline mutation in a familial adenomatous polyposis pedigree].

OBJECTIVE: To detect the adenomatous polyposis coli (APC) gene germline mutation in the proband and her family members with familial adenomatous polyposis (FAP). METHODS: The diagnosis of a patient with FAP was validated by colonoscopy, pathology and the family history. The systematic screening with multiplex ligation-dependent probe amplification (MLPA), denaturing high-performance liquid chromatography (DHPLC) and DNA sequencing were carried out to detect APC gene germline mutations. RESULTS: A novel mutation c.1999 C >T (Q667X) of APC, which leads to premature termination of the protein, was identified in this family. This mutation manifested an aggressive form of FAP with early onset of colorectal adenocarcinoma and colonic adenoma. CONCLUSION: The mutation of APC Q667X is the cause of clinical phenotype of this family with FAP, and the prophylactic colectomy for the affected family members should be considered.

Adenomatous Polyposis Coli↗

PubMed1995

Severe Gardner syndrome in families with mutations restricted to a specific region of the APC gene.

Familial adenomatous polyposis (FAP) is associated with a number of extraintestinal manifestations, which include osteomas, epidermoid cysts, and desmoid tumors, often referred to as "Gardner syndrome." Recent studies have suggested that some of the phenotypic features of FAP are dependent on the position of the mutation within the APC gene. In particular, the correlation between congenital hypertrophy of the retinal pigment epithelium (CHRPE) and APC genotype indicates that affected families may be divided into distinct groups. We have investigated the association between the dentoosseous features of GS on dental panoramic radiographs (DPRs) and APC genotype in a regional cohort of FAP families. DPRs were performed on 84 affected individuals from 36 families, and the dento-osseous features of FAP were quantified by a weighted scoring system. Significant DPR abnormalities were present in 69% of affected individuals. The APC gene mutation was identified in 27 of these families, and for statistical analysis these were subdivided into three groups. Group 1 comprised 18 affected individuals from seven families with mutations 5' of exon 9; these families (except one) did not express CHRPE. Groups 2 comprised 38 individuals from 16 families with mutations between exon 9 and codon 1444, all of whom expressed CHRPE. Group 3 comprised 11 individuals from four families with mutations 3' of codon 1444, none of whom expressed CHRPE. Families with mutations 3' of codon 1444 had significantly more lesions on DPRs (P < .001) and appeared to have a higher incidence of desmoid tumors. These results suggest that the severity of some of the features of Gardner syndrome may correlate with genotype in FAP.

DNA↗

PubMed1993

Association of the APC gene product with beta-catenin.

Mutations in the human APC gene are linked to familial adenomatous polyposis and to the progression of sporadic colorectal and gastric tumors. To gain insight into APC function, APC-associated proteins were identified by immunoprecipitation experiments. Antibodies to APC precipitated a 95-kilodalton protein that was purified and identified by sequencing as beta-catenin, a protein that binds to the cell adhesion molecule E-cadherin. An antibody specific to beta-catenin also recognized the 95-kilodalton protein in the immunoprecipitates. These results suggest that APC is involved in cell adhesion.

Adenomatous Polyposis Coli Protein↗

PubMed1997

Molecular analysis of the APC gene in 105 Dutch kindreds with familial adenomatous polyposis: 67 germline mutations identified by DGGE, PTT, and southern analysis.

Germline mutations of the adenomatous polyposis coli (APC) gene are responsible for familial adenomatous polyposis (FAP), an autosomal dominant predisposition to colorectal cancer. We screened the entire coding region of the APC gene for mutations in an unselected series of 105 Dutch FAP kindreds. For the analysis of exons 1-14, we employed the GC-clamped denaturing gradient gel electrophoresis (DGGE), while the large exon 15 was examined using the protein truncation test. Using this approach, we identified 65 pathogenic mutations in the above 105 apparently unrelated FAP families. The mutations were predominantly either frameshifts (39/65) or single base substitutions (18/65), resulting in premature stop codons. Mutations that would predict abnormal RNA splicing were identified in seven cases. In one of the families, a nonconservative amino acid change was found to segregate with the disease. In spite of the large number of APC mutations reported to date, we identified 27 novel germline mutations in our patients, which reiterates the great heterogeneity of the mutation spectrum in FAP. In addition to the point mutations identified in our patients, structural rearrangements of APC were found in two pedigrees, by Southern blot analysis. The present study indicates that the combined use of DGGE, protein truncation test, and Southern blot analysis offers an efficient strategy for the presymptomatic diagnosis of FAP by direct mutation detection. We found that the combined use of the currently available molecular approaches still fails to identify the underlying genetic defect in a significant subset of the FAP families. The possible causes for this limitation are discussed.

Adenomatous Polyposis Coli↗

PubMed1996

A novel deletion at codon 441 of the APC gene associated with ophthalmic lesions (CHRPE) in a South African family.

A novel mutation at codon 441 in exon 10 of the adenomatous polyposis coli (APC) gene was identified in a South African family of mixed ancestry, using a convenient, non-radioactive, heteroduplex-SSCP screening assay. This single thymidine deletion after nucleotide position 1322 creates a frameshift resulting in a downstream stop codon at amino acid residue 453 of the APC gene. Genotypes of nine family members were subsequently correlated with the presence or absence of congenital hypertrophy of the retinal pigment epithelium (CHRPE), since expression of this common extracolonic manifestation of FAP is largely determined by the length of the truncated protein. CHRPE was absent in the five unaffected family members analysed, while four mutation positive subjects showed these ophthalmic lesions. Correlation between the molecular analysis and ophthalmic examinations, performed without knowledge of clinical and genetic status respectively, provided additional evidence in favour of the view that the range of phenotypic expression in FAP may result from different allelic manifestations of APC mutations.

Adenomatous Polyposis Coli↗

PubMed1996

Characterization of the APC gene in sporadic gastric adenocarcinomas.

The prominent role of the APC gene in colorectal tumor development is well established. However, its role in tumorigenesis in other tissues is not clear. Hence, DNA from 30 primary sporadic gastric adenocarcinomas was obtained from patients living in a high risk area of the world (North-Central Italy) in order to further define APC's role in gastric tumorigenesis. We thoroughly examined that region of APC which is commonly mutated in colorectal tumors using proven sensitive methods. The IVS protein assay and DNA sequence analysis of APC codons 686 through 1693 revealed no intragenic mutations. However, allelic loss of loci near APC was detected in 7 (28%) of 25 informative gastric adenocarcinomas using two 5q dinucleotide repeat markers for LOH analysis. These results suggest that genetic alteration of a region of APC commonly mutated in colorectal cancer is not a common event during sporadic gastric tumor development, at least in patients from North-Central Italy. Further analysis of chromosome 5q might identify another gene to be significantly altered in these gastric cancers.

Adenocarcinoma↗

PubMed2001

Submerged gel electrophoresis on Spreadex gels--a new method for APC gene mutation detection.

Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease. Patients with FAP develop hundreds to thousands of adenomatous polyps in the colon and rectum during their 2nd or 3rd decades, and one or more of them progress to cancer if left without surgical treatment. The gene responsible for FAP was identified in 1991 and termed the APC (adenomatous polyposis coli) gene. Following identification of APC, a number of germ-line mutations responsible for the development of the disease were found. The purpose of this study was to determine the usefulness of a new method, submerged gel electrophoresis, in the detection of the most-frequent mutation of the APC gene [5-base pair (bp) deletion in codon 1309], especially in the presymptomatic diagnosis of FAP. Genomic DNAs were isolated from peripheral blood of patients and their relatives. We used two methods, electrophoresis on polyacrylamide gel and submerged gel electrophoresis, for the identification of APC gene codon 1309 mutation. After only 110 min PCR fragments of 91 bp and 86 bp (5-bp deletion) were completely resolved on a Spreadex EL300 gel. Our results showed that electrophoresis using Spreadex gels provides a simple and rapid non-radioactive method for determination of the most-frequent germ-line mutations in the APC gene.

Adenomatous Polyposis Coli↗

PubMed1994

APC gene mutations in the mutation cluster region are rare in esophageal cancers.

BACKGROUND/AIMS: The molecular pathogenesis of esophageal cancers is not completely understood. Frequent allelic losses occur on chromosome 5q, suggesting the presence of a tumor-suppressor gene that is important in esophageal tumorigenesis. Because the APC gene is located on chromosome 5q, we sought to determine its involvement as a candidate tumor-suppressor gene in esophageal carcinogenesis. METHODS: Thirty-five esophageal squamous cell carcinomas and 18 adenocarcinomas were collected with corresponding normal gastric mucosae. A region of APC spanning codons 686-1693 and including most reported mutations was screened for truncating mutations using an in vitro synthesized protein assay. Single-strand conformation polymorphism analysis was also used to examine APC codons 764-842 and codons 1032-1310 for missense and nonsense mutations. RESULTS: One squamous cell carcinoma and one adenocarcinoma each contained a truncating mutation within the mutation cluster region of APC. CONCLUSIONS: The discovery of two truncating mutations identifies APC as a gene involved in a subset of esophageal carcinomas. The low rate of APC mutation observed here, coupled with the high reported rate of loss of heterozygosity on chromosome 5q, suggests the possibility that a gene or genes on chromosome 5q distinct from APC may be the target(s) of allelic deletion in most esophageal tumors.

Adenocarcinoma↗

PubMed1999

Germline mutations are frequent in the APC gene but absent in the beta-catenin gene in familial adenomatous polyposis patients.

Inactivation of the adenomatous polyposis coli (APC) gene has been shown to initiate the majority of colorectal cancer (CRC), including a familial form called familial adenomatous polyposis (FAP). One consequence of the APC mutation is the activation of the beta-catenin (CTNNB1)/T-cell transcription factor (Tcf) pathway. A recent study has shown that about half of the sporadic CRC lacking APC mutation has CTNNB1 mutation, suggesting that CTNNB1 mutation can substitute for APC mutation in the initiation of colorectal tumorigenesis. However, the frequency of CTNNB1 germline mutation in FAP has not been reported. In the present study, we investigated the frequencies of APC and CTNNB1 germline mutations in 26 unrelated FAP families. We used the Protein Truncation Test (PTT) to screen the entire coding region of APC and found germline mutations in twenty families. We then screened for CTNNB1 germline mutations in the rest of the families lacking detectable APC mutations. No missense mutations at GSK-3beta phosphorylation sites or interstitial deletion of exon 3 of CTNNB1 was found. Our results indicate that APC germline mutations are frequent but CTNNB1 germline mutations are rare in FAP patients, suggesting that CTNNB1 mutation cannot substitute for APC mutation in the initiation of FAP. Genes Chromosomes Cancer 25:396-398, 1999.

Adenomatous Polyposis Coli↗

PubMed2005

Large deletions of the APC gene in 15% of mutation-negative patients with classical polyposis (FAP): a Belgian study.

Germline mutations of the APC gene are responsible for familial adenomatous polyposis (FAP). Most of the mutations are protein truncating mutations and are spread over the coding region. Rare whole-gene deletions or exonic deletions have been described. From a series of 85 patients clinically diagnosed with FAP or attenuated FAP (AAPC) in our center, 30 (35%) were found to have truncating or missense mutations. We have now screened the remaining 55 patients for exonic deletions or duplications, first by semi-quantitative PCR and later by multiplex ligation-dependent probe amplification (MLPA). Three whole-gene deletions and one exon 14 deletion were found (5% of patients). The whole-gene deletions were confirmed by fluorescence in situ hybridization (FISH) analysis, and the breakpoints of the exon 14 deletion could be determined using long range PCR. Further characterization of the whole gene deletions was performed using extragenic polymorphic markers and/or semi-quantitative PCR. We could demonstrate that the deletions do not encompass the MCC gene. Interestingly, the phenotype of the deletion patients was not different from that of patients with truncating mutations. The polyp numbers ranged from attenuated to profuse polyposis and the interfamilial variability of disease phenotype was as in other FAP families. In none of the 28 AAPC patients included in this study, was a large deletion found, while 15% of the patients with classical polyposis had a genomic deletion. It corroborates recently published data, suggesting that large deletions may occur with a frequency higher than 10% in mutation-negative patients with a classical polyposis. In this article, we have included an overview of genomic rearrangements in the 5q21 region.

Adenomatous Polyposis Coli↗

PubMed1995

Genotype-phenotype correlations of new causative APC gene mutations in patients with familial adenomatous polyposis.

Nine new causative mutations and seven previously characterised mutations of the APC gene of patients with familial adenomatous polyposis (FAP) were analysed for any genotype-phenotype correlations. The only clear genotype-phenotype correlation found was between the position of the mutation site and the presence or absence of congenital hypertrophy of the retinal pigment epithelium (CHRPE). A more distal mutation site was associated with an earlier age of onset of symptoms and a larger number of colonic polyps, but a notable amount of intrafamilial variation was observed.

Adenomatous Polyposis Coli↗

PubMed1992

Two intragenic polymorphisms of the APC-gene detected by PCR and enzymatic digestion.

The gene causing adenomatous polyposis coli (APC) has recently been cloned. Three intragenic polymorphisms were reported to be detectable by single-strand conformation polymorphism analysis. Here, we describe an assay using polymerase-chain-reaction-based amplification and subsequent enzymatic digestion of genomic sequences to identify polymorphic sites at nucleotide positions 1458 and 5037 of the APC gene.

Adenomatous Polyposis Coli↗

PubMed2004

Mutation analysis of the adenomatous polyposis coli (APC) gene in Danish patients with familial adenomatous polyposis (FAP).

Development of one hundred or more adenomas in the colon and rectum is diagnostic for the dominantly inherited, autosomal disease Familial Adenomatous Polyposis (FAP). It is possible to identify a mutation in the Adenomatous Polyposis Coli (APC) gene in approximately 80% of the patients, and almost 1,000 different pathogenic mutations have been identified in the APC gene up till now. We report 12 novel and 24' previously described germline APC mutations from 48 unrelated Danish families. Four families with the mutation localized in the 3' region of the gene showed great variance in phenotypic presentation.

3' Flanking Region↗