UMLS:C0033036 - FACTA Search

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Query: UMLS:C0033036 (APC)
10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the significance of alterations in DNA methylation during multistage carcinogenesis of the pancreas, tissue samples of 13 peripheral pancreatic duct epithelia showing no remarkable histological changes without inflammatory background (DE), 20 peripheral pancreatic duct epithelia showing no remarkable histological changes with inflammatory background (DEI), 40 pancreatic intraepithelial neoplasias (PanIN) and 147 areas of ductal carcinoma were microdissected from surgically resected specimens from 58 patients and were embedded into agarose beads. The embedded tissue samples were subjected to methylation-specific PCR (MSP) to evaluate the DNA methylation status of the p14, p15, p16, p73, APC, hMLH1, MGMT, BRCA1, GSTP1, TIMP-3, CDH1 and DAPK-1 genes. The prevalence of DNA methylation of at least one of the 12 genes and the average number of methylated genes were significantly higher in both DEI (60% and 0.85 +/- 0.88, P = 0.0151 and P = 0.0224, respectively) and PanIN (67.5% and 0.95 +/- 0.85, P = 0.0014 and P = 0.0028, respectively) than in DE (15.4% and 0.15 +/- 0.38), and were further increased in ductal carcinoma (98.3% and 2.50 +/- 1.35, P < 0.0001 and P < 0.0001, respectively). The BRCA1, APC, p16 and TIMP-3 genes were frequently methylated in ductal carcinoma (60.3, 58.6, 39.3 and 30.9%, respectively). Considerable heterogeneity of DNA methylation status was observed among multiple microdissected areas from individual ductal carcinomas, and the number of methylated genes per area was significantly correlated with poorer tumor differentiation (P = 0.0249). The average number of methylated genes in ductal carcinomas was significantly correlated with DNMT1 protein expression level (P = 0.0093). These data suggest that accumulation of DNA methylation of multiple tumor-related genes is involved in multistage carcinogenesis of the pancreas from early precancerous stages to malignant progression and that DNMT1 protein overexpression may be responsible for this aberrant DNA methylation.
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PMID:DNA methylation of multiple tumor-related genes in association with overexpression of DNA methyltransferase 1 (DNMT1) during multistage carcinogenesis of the pancreas. 1653 62

Colorectal cancer (CRC) is the second leading cause of mortality of malignant diseases in Hungary and according to the incidence and prevalence of CRC Hungary is second among European countries. Hence, it is of outstanding interest to know the current concepts on pathogenesis and genetical background of CRC, as well as incorporate this knowledge in the everyday practice. In the first part of the review authors address the genetic background of hereditary colorectal cancer syndromes. In fact, a positive family history may be found in 20-30% and genetically defined trait (e.g. familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC) and Peutz-Jeghers-syndrome (PJS)) is responsible for 3-5% of all colon cancers. Germline mutations of tumor suppressor gene, APC (5q21) are found in 70-90% of the cases. Until now more than 300 mutations were identified. Though a typical mutation was not found, the location of the mutation is associated to the clinical phenotype and prognosis. Of note, beside APC mutations, biallelic mutations of the MYH gene may be found in a subset of individuals with FAP. The diagnosis of HNPCC is based on family history and the presence of Amsterdam I-Il or Bethesda criteria. The genetic background and clinical phenotype of the syndrome is heterogeneous. Mutations of different mismatch repair genes (mainly hMLH1 or hMSH2) may be identified in most cases. Genetic testing is advised in first degree relatives of FAP patients, if genetic testing is not available colonoscopic surveillance should be done starting at the age of 10-12 years. Due to the high number of mutation genetic testing is difficult in HNPCC families and colonoscopic screening should be advised to affected families.
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PMID:[Current concepts in the genetics of hereditary and sporadic colorectal cancer and the role of genetics in patient management. Hereditary colorectal cancers]. 1657 36

Small bowel adenocarcinoma (SB-AC) is a very rare tumor entity. Epigenetic alterations, including hypermethylation of DNA mismatch repair genes and tumor suppressor genes, seem to be important for carcinogenesis in tumors of the gastrointestinal tract, but have not yet been investigated in SB-AC. In the current study, the prevalence of hypermethylation in a panel of genes involved in gastrointestinal carcinogenesis (hMLH1, HPP1, p14(ARF), p16(INK4A), APC) was determined in a series of SB-AC. Paraffin-embedded tumor samples from 56 patients with SB-AC who underwent surgical resection between January 1985 and December 2003 were investigated for hypermethylation by means of methylation-specific real-time PCR, and compared with our findings in a previously investigated series of 50 gastric adenocarcinomas. In comparison with adenocarcinomas of the stomach, SB-AC revealed a significantly higher rate of hypermethylation of HPP1 (86% versus 54%, p = 0.0003), p16(INK4A) (32% versus 10%, p = 0.0006), and a significantly lower rate of hypermethylation of APC (48% versus 84%, p = 0.0001). Hypermethylation of hMLH1 and p14(ARF) was present in 23% and 9% of SB-AC, respectively. Locally advanced tumor categories (pT3/4) showed a higher rate of hypermethylation of HPP1 (90%) than did early tumor categories (pT1/2 categories, 40%; p = 0.0036). This was also reflected by the correlation between the HPP1 hypermethylation and high UICC stage (p = 0.02). No correlation was found between hypermethylation and other clinicopathologic parameters such as age, tumor grade and nodal status. Our findings suggest that hypermethylation of hMLH1, HPP1, p16(INK4A) and APC is frequent in primary adenocarcinomas of the small bowel. The differences in the hypermethylation spectrum of small bowel and stomach cancer indicate significant epigenetic differences between these tumors.
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PMID:Hypermethylation of hMLH1, HPP1, p14(ARF), p16(INK4A) and APC in primary adenocarcinomas of the small bowel. 1661 16

The multistep development of malignant tumors with increasing accumulation of genetic alterations from preneoplastic lesions to invasive carcinoma is an accepted model of carcinogenesis. Urothelial carcinoma of the bladder and upper urinary tract is an interesting model system to study tumor development and progression. There is both clinical and molecular evidence that urothelial carcinoma can be divided in two groups with different characteristics: 1) well differentiated genetic stable and mostly superficial papillary tumors with frequent recurrence and low progression risk and 2) poorly differentiated mostly solid and invasive tumors with a high number of genetic alterations. The aim of the studies summarized in this manuscript were: 1) to identify genetic changes with importance for urothelial carcinogenesis by investigation of preneoplastic and early neoplastic urothelial lesions, 2) to define molecular markers for progression of papillary carcinoma, and 3) to investigate the importance of microsatellite instability and mismatch repair defects for development of tumors of the upper urinary tract which are frequently found within the HNPCC syndrome. The investigation of urothelial hyperplasias, dysplasias and carcinoma in situ by deletion mapping (LOH analysis), FISH, CGH and mutation detection revealed that urothelial hyperplasias are precursors of papillary bladder tumors and flat dysplasias can be regarded as precursors of solid bladder cancers. In bladder cancer patients, there are genetic alterations already detectable in histologically inconspicous urothelium. The investigation of papillary bladder cancers for progression-related genetic alterations showed that mutations in the wnt pathway genes APC and beta-Catenin do not play an important role in urothelial carcinogenesis. Instead, the expression of the antagonistic wnt-related genes WIF-1 and sFRPI is strongly reduced in bladder cancer and associated with poor prognosis in papillary tumors. Loss of sFRP1 expression is not due to gene mutation but to epigenetic inactivation by promoter hypermethylation and is related to deletions at chromosome 8p12. In contrast to bladder cancers, tumors of the ureter and renal pelvis develop through a different genetic pathway in 30% of cases. The loss of mismatch repair proteins (hMSH2, hMLH1 or hMSH6) leads to a mutator phenotype with accumulation of genetic alterations in multiple repetitive sequences (microsatellite instability, MSI). MSI-positive tumors were predominantly located in the ureter and showed a lower tumor stage and grade and papillary and frequently inverted growth pattern. They were more frequent in females and younger patients and had a higher incidence of colorectal carcinomas and other tumors in the family. Chromosome 9 deletions, a hallmark of urothelial carcinomas, and the number of chromosomal alterations as detected by CGH analysis were significantly less frequent in these tumors. These data strongly suggest a distinct molecular pathway in the development of upper urinary tract tumors with mutator phenotype.
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PMID:[Molecular changes in development and progression of urothelial carcinoma]. 1688 10

Epigenetic mechanisms in carcinogenesis may have a significant role in the development of colorectal cancer. To investigate this phenomenon in early-stage disease, promoter methylation status in the tumour suppressor genes APC, MGMT, hMLH1, P14/P14ARF, and CDKN2A/P16 was investigated in 78 colorectal adenomas. These had previously been characterized for mutations of APC, KRAS, and TP53 genes and for chromosomal abnormality by comparative genomic hybridization (CGH). APC hypermethylation was seen in 52 tumours (66.7%). APC showed either methylation or mutation in 66 lesions (84.6%), but these events were not statistically associated. MGMT methylation was detected in 39 cases (50%). Adenomas with this abnormality showed a significantly lower number of chromosomal changes by CGH (p < 0.02), confirming that DNA repair defect of this type is associated with a lower level of chromosomal instability. An hMLH1 methylation defect was seen in only one adenoma (1.3%), from a patient who had a synchronous cancer showing the same defect. Methylation of P14 (P14ARF) was seen in 31 adenomas (39.7%) and CDKN2A (P16) abnormality in 25 (32.1%). DNA methylation at two or more loci was seen in 46 tumours (59%), while 11 lesions (14.1%) showed no evidence of hypermethylation at any of the loci studied. Methylation at any or all of MGMT, P14 or P16 was significantly associated with APC methylation (p = 0.01). Those neoplasms with more than two methylated genes showed significantly fewer chromosomal abnormalities than adenomas with one or no methylated loci (p < 0.001). There was no association between specific individual chromosomal abnormalities, APC, KRAS or TP53 mutations and any pattern of methylation abnormality. We conclude that methylation abnormality is very common in pre-invasive colorectal neoplasia, and that high level methylation is associated with low level chromosomal instability.
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PMID:Relationship between point gene mutation, chromosomal abnormality, and tumour suppressor gene methylation status in colorectal adenomas. 1690 13

Tumors of the nervous system most often occur in both children and adults as sporadic events with no family history of the disease, but they are also among the clinical manifestations of a significant number of familial cancer syndromes, including familial retinoblastoma, neurofibromatosis 1 and 2, tuberous sclerosis, and Cowden, Turcot, Li-Fraumeni and nevoid basal cell carcinoma (Gorlin) syndromes. All of these syndromes involve transmissible genetic risk resulting from loss of a functional allele, or inheritance of a structurally defective allele, of a specific gene. These genes include RB1, NF1, NF2, TSC1, TSC2, TP53, PTEN, APC, hMLH1, hPSM2, and PTCH, most of which function as tumor suppressor genes. The same genes are also observed in mutated and inactive forms, or are deleted, in tumor cells in sporadic cases of the same tumors. The nature of the mutational events that give rise to these inactivated alleles suggests a possible role of environmental mutagens in their causation. However, only external ionizing radiation at high doses is clearly established as an environmental cause of brain, nerve and meningeal tumors in humans. Transplacental carcinogenesis studies in rodents and other species emphasize the extraordinary susceptibility of the developing mammalian nervous system to carcinogenesis, but the inverse relationship of latency to dose suggests that low transplacental exposures to genotoxicants are more likely to result in brain tumors late in life, rather than in childhood. While not all neurogenic tumor-related genes in humans have similar effects in experimental rodents, genetically engineered mice (GEM) increasingly provide useful insights into the combined effects of multiple tumor suppressor genes and of gene-environment interactions in the genesis of brain tumors, especially pediatric brain tumors such as medulloblastoma.
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PMID:Inducible and transmissible genetic events and pediatric tumors of the nervous system. 1701 46

Epigenetic abnormalities including the aberrant DNA hypermethylation of the promoter CpG islands play a key role in the mechanism of gene inactivation in cell carcinogenesis. To identify the genes associated with aberrant DNA hypermethylation in endometrial carcinogenesis, we studied the hypermethylation of the promoter regions of five genes: hMLH1, APC, E-cadherin, RAR-beta and p16. The frequencies of aberrant hypermethylation were 40.4% (21/52) in hMLH1, 22% (11/50) in APC, 14% (7/50) in E-cadherin, and 2.3% (1/44) in RAR-beta in endometrial cancer specimens. No aberrant DNA methylation was found in p16. In atypical endometrial hyperplasia, the frequencies of aberrant methylation were 14.3% (2/14) in hMLH1 and 7.3% (1/14) in APC, whereas normal endometrial cells showed no aberrant hypermethylation of any of the five genes. The high frequencies of the aberrant DNA hypermethylation of hMLH1, APC and E-cadherin suggest that the methylation of the DNA mismatch repair and Wnt signal-related genes may be associated with endometrial carcinogenesis.
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PMID:Relationship of the aberrant DNA hypermethylation of cancer-related genes with carcinogenesis of endometrial cancer. 1708 36

Folate deficiency has been associated with colorectal cancer risk and may be involved in colorectal carcinogenesis through increased chromosome instability, gene mutations, and aberrant DNA methylation. Within the Netherlands Cohort Study on diet and cancer, we investigated the associations between dietary folate intake and colorectal cancer risk with (APC(+)) and without (APC(-)) truncating APC mutations, accounting for hMLH1 expression and K-ras mutations. In total, 528 cases and 4200 subcohort members were available for data analyses of the study cohort (n = 120,852) from a follow-up period between 2.3 and 7.3 y after baseline. Adjusted gender-specific incidence rate ratios (RR) over tertiles of folate intake were calculated in case-cohort analyses for colon and rectal cancer. Although relatively high folate intake was not associated with overall colorectal cancer risk, it reduced the risk of APC(-)colon tumors in men (RR 0.58, 95% CI 0.32-1.05, P(trend) = 0.06 for the highest vs. lowest tertile of folate intake). In contrast, it was positively associated with APC(+) colon tumors in men (highest vs. lowest tertile: RR 2.77, 95% CI 1.29-5.95, P(trend) = 0.008) and was even stronger when the lack of hMLH1 expression and K-ras mutations were excluded (RR 3.99, 95% CI 1.43-11.14, P(trend) = 0.007). Such positive associations were not observed among women; nor was folate intake associated with rectal cancer when APC mutation status was taken into account. Relatively high folate consumption reduced the risk of APC(-) colon tumors, but folate intake was positively associated with APC(+) colon tumors among men. These opposite results may indicate that folate enhances colorectal carcinogenesis through a distinct APC mutated pathway.
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PMID:Dietary folate and APC mutations in sporadic colorectal cancer. 1711 13

High alcohol consumption is related to colorectal cancer (CRC). Our objective was to study associations between alcohol consumption and risk of CRC according to characteristics of aetiological pathways: the chromosomal instability (CIN) and the microsatellite instability (MIN) pathway. We classified CIN+ tumours (tumours with either a truncating APC mutation, an activating K-ras mutation or overexpression of p53), MIN+ tumours (tumours lacking hMLH1 expression) and CIN- /MIN- tumours (tumours without these defects). In the Netherlands Cohort Study on diet and cancer, 120852 men and women, aged 55-69 years, completed a questionnaire on risk factors for cancer at baseline (1986). Case-cohort analyses were conducted using 573 CRC cases with complete data after 7 x 3 years of follow-up, excluding the first 2 x 3 years. Adjusted incidence rate ratios (RR) and 95 % confidence intervals (CI) were estimated. Compared with abstaining, alcohol consumption of >or=30 g/d was positively associated with the risk of CRC irrespective of genetic or molecular aberrations present, although statistical significance was not reached (RR 1 x 35 (95 % CI 0 x 9-2 x 0) for the CIN+ tumours, RR 1 x 59 (95 % CI 0 x 4-5 x 8) for the MIN+ tumours and RR 1.15 (95 % CI 0 x 5-2 x 7) for the CIN- /MIN- tumours). Beer, wine and liquor consumption were, independent of their alcoholic content, not consistently associated with the risk of CRC within the defined subgroups. In conclusion, our results indicate that a daily alcohol consumption of >or=30 g is associated with an increase in risk of CRC, independent of the presence or absence of the studied characteristics of different aetiological pathways.
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PMID:Alcohol consumption and distinct molecular pathways to colorectal cancer. 1731 2

We performed this study to investigate the aberrant methylation profile of the cancer-related genes in Korean non-small cell lung cancer (NSCLC) that previously exhibited high frequencies of methylation in Western populations. The aberrant promoter methylation of eight genes (GSTP1, p16, FHIT, APC, RASSF1A, hMLH1, hMSH2, AGT) was determined by MSP in 99 surgically resected NSCLCs and their corresponding nonmalignant lung tissues. Methylation in the tumor samples was detected at 15% for GSTP1, 22% for p16, 34% for FHIT1, 48% for APC, 40% for RASSF1A, 18% for hMLH1, 8% for hMSH2 and 21% for AGT, whereas it occurred at lower frequencies in the corresponding nonmalignant lung tissues, particularly in the p16 (1%) and RASSF1A (1%) genes. These results suggest that the methylation profiles of NSCLCs in a Korean population are similar to those in Western populations.
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PMID:Aberrant DNA methylation profiles of non-small cell lung cancers in a Korean population. 1753 92

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