OBJECTIVETo analyze the mutational features of adenomatous polyposis coli (APC) gene and to explore the effect of mismatch repair (MMR) deficiency on its mutations in hereditary non-polyposis colorectal cancers (HNPCC).

METHODSPCR-based in vitro synthesized protein test (IVSP) assay and sequencing analysis were used to confirm somatic mutations of whole APC gene in 19 HNPCC patients.

RESULTSEleven cases with thirteen mutations were determined. The frequency of APC mutation was 58%(11/19). The exhibiting mutations consisted of 9 frameshift mutations and 4 nonsense ones, indicating the existence of more frameshift mutations (69%). All of frameshift mutations were deletion or insertion of 1-2 bp and most of them (7/9) happened at simple nucleotide repeat sequences, particularly within (A) n tracts (5/9). All of four nonsense mutations resulted from C to T transitions at CpG sites.

CONCLUSIONMutational inactivations of APC gene were detected in more than half of HNPCC patients in this study, indicating that APC mutation is a common molecular event in the tumorigenesis of HNPCC. According to the location of frameshift mutations at simple nucleotide repeat sequences and point mutations at CpG sites, it was suggested that endogenous mechanisms like MMR deficiency might exert an effect on the nature of APC mutations in most HNPCC.

Adenomatous Polyposis Coli ; genetics ; Adenomatous Polyposis Coli Protein ; genetics ; metabolism ; Carcinoma ; genetics ; Colorectal Neoplasms ; genetics ; pathology ; Colorectal Neoplasms, Hereditary Nonpolyposis ; genetics ; Genes, APC ; physiology ; Humans

OBJECTIVETo explore the characteristics of adenomatous polyposis coli (APC) gene germline mutations in Chinese patients with familial adenomatous polyposis (FAP).

METHODSEighteen members from nine FAP pedigrees were studied by using multiplex ligation-dependent probe amplification(MLPA) to detect large fragment deletion of APC gene. Then, PCR were performed to amplify all exons of APC gene for mutation screening by denaturing high performance liquid chromatography (DHPLC). When abnormal elution profile of DHPLC was found, DNA sequencing was performed to determine the mutations.

RESULTSMutations were identified in three pedigrees among the nine pedigrees. They were c.3184_3187 del CAAA in pedigree 2, c.5432C to T in pedigree 4 and c.3925_3929 del AAAAG in pedigree 9 respectively. Among them, c.5432C to T was novel.

CONCLUSIONAPC gene germline mutations can cause the development of FAP. The FAP patients without APC gene germline mutations could be caused by other mechanisms.

Adenomatous Polyposis Coli ; genetics ; Adult ; Chromatography, High Pressure Liquid ; Female ; Genes, APC ; physiology ; Genetic Predisposition to Disease ; genetics ; Germ-Line Mutation ; Humans ; Male ; Middle Aged ; Pedigree

OBJECTIVETo analyze the adenomatous polyposis coli (APC) gene mutations in familial adenomatous polyposis (FAP) in Chinese.

METHODSDNA was extracted from blood samples taken from 31 FAP families, and all exons of the APC gene were amplified with touch-down PCR. APC gene mutations were screened by denaturing high performance liquid chromatography followed by sequencing if abnormal profile was detected.

RESULTSTwelve categories of APC gene mutations were found in 15 FAP families (48.39%) including 4 novel mutations in coding region and 3 mutations in introns. The 4 novel mutations in coding region were frameshift mutations and located in codons 255, 677, 1192 and 1403 respectively. Most mutations were clustered in exon 15 of APC gene leading to frameshift and accounted for 86.67%. Others were nonsense mutations (13.33%).

CONCLUSIONThe mutation rate of the APC gene in this group of Chinese FAP families was about 48.39%, and 4 novel mutations were detected. Frameshift mutation was the major mutation type in Chinese FAP and mainly located in exon 15.

Adenomatous Polyposis Coli ; genetics ; Chromatography, High Pressure Liquid ; methods ; Exons ; genetics ; Female ; Frameshift Mutation ; genetics ; Genes, APC ; physiology ; Humans ; Introns ; genetics ; Male ; Mutation ; Polymerase Chain Reaction

BACKGROUND/AIMS: To identify the risk factors for metachronous gastric neoplasms in patients who underwent an endoscopic resection of a gastric neoplasm. METHODS: We prospectively collected clinicopathologic data and measured the methylation levels of HAND1, THBD, APC, and MOS in the gastric mucosa by methylation-specific real-time polymerase chain reaction in patients who underwent endoscopic resection of gastric neoplasms. RESULTS: A total of 257 patients with gastric neoplasms (113 low-grade dysplasias, 25 high-grade dysplasias, and 119 early gastric cancers) were enrolled. Metachronous gastric neoplasm developed in 7.4% of patients during a mean follow-up of 52 months. The 5-year cumulative incidence of metachronous gastric neoplasm was 4.8%. Multivariate analysis showed that moderate/severe corpus intestinal metaplasia and family history of gastric cancer were independent risk factors for metachronous gastric neoplasm development; the hazard ratios were 4.12 (95% confidence interval [CI], 1.23 to 13.87; p=0.022) and 3.52 (95% CI, 1.09 to 11.40; p=0.036), respectively. The methylation level of MOS was significantly elevated in patients with metachronous gastric neoplasms compared age- and sex-matched patients without metachronous gastric neoplasms (p=0.020). CONCLUSIONS: In patients who underwent endoscopic resection of gastric neoplasms, moderate/severe corpus intestinal metaplasia and a family history of gastric cancer were independent risk factors for metachronous gastric neoplasm, and MOS was significantly hypermethylated in patients with metachronous gastric neoplasms.
Aged ; Basic Helix-Loop-Helix Transcription Factors/genetics ; DNA Methylation ; Female ; Gastrectomy/methods ; Genes, APC/physiology ; Genes, mos/genetics ; Humans ; Incidence ; Male ; Middle Aged ; Multivariate Analysis ; Neoplasms, Second Primary/epidemiology/*genetics/pathology ; Proportional Hazards Models ; Risk Factors ; Stomach Neoplasms/genetics/*pathology/surgery ; Thrombomodulin/genetics

OBJECTIVETo investigate the status of hypermethylation in the promoter 1A region of the adenomatus polyposis coli (APC) gene in 3 familial adenomatous polyposis (FAP) pedigrees and to screen large fragment deletions in the APC gene.

METHODSDNA from tumor tissues and corresponding normal tissues of 5 FAP patients was modified by sodium bisulfite. Then the methylation status of the APC gene was analyzed by methylation specific-PCR (MSP) and DNA sequencing. Multiplex ligation-dependent probe amplification (MLPA) was used to screen aberrations involving large fragments from all the 15 exons and promoter region of APC gene.

RESULTSNo methylation was present in normal tissues. Hypermethylation was found in tumor tissues of one proband and her son. Loss of heterozygosity was observed in another patient from the same FAP family.

CONCLUSIONAberrant methylation of the APC promoter region provides an important mechanism for impairing APC function and may occur early during colon neoplasia progression. Loss of heterozygosity may play a role in patients with classical polyposis.

Adenomatous Polyposis Coli ; genetics ; Adenomatous Polyposis Coli Protein ; genetics ; Adult ; Base Sequence ; Colorectal Neoplasms ; genetics ; CpG Islands ; DNA Methylation ; DNA, Neoplasm ; Female ; Gene Expression Regulation, Neoplastic ; Genes, APC ; physiology ; Heterozygote ; Humans ; Loss of Heterozygosity ; Male ; Polymerase Chain Reaction ; Promoter Regions, Genetic ; physiology