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)

Colorectal adenomas have traditionally been regarded as homogeneous. The aim of our study was to identify molecular features that may differentiate sporadic adenomas from familial adenomas such as Familial Adenomatous Polyposis (FAP) and Multiple Adenoma patients. DNA methylation was tested at Methylated IN Tumor (MINT) loci (1,2,12,31) and the CpG promoter region of genes MLH1, HPP1, MGMT, p14ARF and p16INK4a in FAP-associated adenomas (33) from 5 patients with a known APC mutation (Group 1, FAP), adenomas (29) from 4 Multiple Adenoma patients (Group 2 Multiple), adenomas (14) from 3 patients with sporadic colorectal cancers showing high microsatellite instability (Group 3, MSI-H) and adenomas (16) from 7 patients, with sporadic colorectal cancers showing microsatellite stable or low level instability (Group 4, MSS/MSI-L). Aberrant Crypt Foci (ACFs), Hyperplastic Polyps (HPs) and cancers were also examined for methylation status as well as K-ras mutation. Multiple Adenoma patients were examined for germline polymorphisms in the base excision repair gene, MYH. The familial syndrome, FAP -associated adenomas showed a significantly low frequency of MINT methylation (15.5%,) compared to sporadic MSS/MSI-L-associated adenomas (35.5%). Group 3 (MSI-H) adenomas were different in that many showed serration and a high level of methylation (57.1%). Group 2, Multiple Adenoma cases, resembled sporadic MSS/MSI-L-associated adenomas. However the promoter regions of key genes, MGMT, p14ARF and p16INK4a were methylated to a greater extent than MINTs in both sporadic and familial adenomas. Genetic profiling of adenomas supports the concept that adenomas belonging to familial syndromes pursue a different pathway to tumorigenesis than their sporadic counterpar/ts from their earliest formation.
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PMID:DNA methylation patterns in adenomas from FAP, multiple adenoma and sporadic colorectal carcinoma patients. 1615 25

Genetic and epigenetic alterations are considered to play important roles in lung cancer. Recent studies showed that EGFR and K-RAS mutations exhibited a mutually exclusive pattern in adenocarcinoma of the lung, suggesting the presence of two independent oncogenic pathways. However, it is unknown how epigenetic alterations were involved in lung carcinogenesis mediated by EGFR or K-RAS mutation. In this study, we examined the relationship between genetic and epigenetic alterations in 164 cases of lung adenocarcinoma. Somatic mutations were determined by direct sequence of EGFR exons 18 to 21 and K-RAS codons 12 and 13. Methylation status of p16(INK4a), RASSF1A, APC, RARbeta, and CDH13, frequently methylated in lung cancer, was determined by methylation-specific PCR and the degree of methylation was defined as the methylation index. Multivariate analysis adjusted for age, sex, and smoking dose showed that the probability of having EGFR mutation was significantly lower among those with p16(INK4a) and CDH13 methylation than in those without [p16(INK4a): odds ratio (OR), 0.07; 95% confidence interval (95% CI), 0.02-0.33; CDH13: OR, 0.34; 95% CI, 0.15-0.77] and the methylation index was significantly lower in EGFR mutant cases than in wild type (OR, 0.70; 95% CI, 0.52-0.95). By contrast, K-RAS mutation was significantly higher in p16(INK4a) methylated cases than in unmethylated cases (OR, 4.93; 95% CI, 1.54-15.7) and the methylation index was higher in K-RAS mutant cases than in wild type with marginal significance (OR, 1.46; 95% CI, 0.95-2.25). Our results indicate the differences in the evolvement of epigenetic alterations between the EGFR- and K-RAS-mediated tumorigenesis and suggest the specific interaction of genetic and epigenetic changes in tumorigenesis of lung cancer.
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PMID:Mutational and epigenetic evidence for independent pathways for lung adenocarcinomas arising in smokers and never smokers. 1645 91

Ependymomas (EP) represent the third most frequent type of central nervous system (CNS) tumor of childhood, after astrocytomas and medulloblastomas. No prognostic biological markers are available, and differentiation from choroid plexus papilloma (CPP) is difficult. The present objective was, for a sample of 27 children with intracranial EP and 7 with CPP, to describe and compare the methylation status of 19 genes (with current HUGO symbol, if any): p15INK4a (CDKN2B), p16INK4a and p14ARF (both CDKN2A), APC, RB1, RASSF1A (RASSF1), BLU (ZMYND10) FHIT, RARB, MGMT, DAPK (DAPK1), ECAD (CDH1), CASP8, TNFRSF10C, TNFRSF10D, FLIP (CFLAR), INI1 (SMARCB1), TIMP3, and NF2. Three adult corteses were used as a control. We detected a similar percentage of methylated tumors in both groups (71% in CPP and 77% in EP). No gene was methylated in that control group. RASSF1A was the most frequently methylated gene in both benign tumors (66%) and EP (56%). The genes associated with apoptosis were methylated in both groups of tumors. The percentages of TRAIL pathway genes (CASP8, TFRSF10C, and TFRSF10D) methylated were 30, 9.5, and 36.4%, respectively, in ependymomas and 50, 50, and 16.7%, respectively, in choroid plexus papillomas. No other gene was methylated in the benign tumors, whereas FHIT was methylated in 22%, RARB in 14.8%, BLU in 13.6%, p16INK4a in 11.1%, TNFRSF10C in 9.5%, and DAPK in 7.4% of ependymomas. Although we did not observe a statistical relationship between methylation and clinical outcome, the methylation pattern does not appear to be randomly distributed in ependymoma and may represent a mechanism of tumor development and evolution.
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PMID:Methylation of RASSF1A and TRAIL pathway-related genes is frequent in childhood intracranial ependymomas and benign choroid plexus papilloma. 1661 14

The panel of 60 human cancer cell lines (the NCI-60) assembled by the National Cancer Institute for anticancer drug discovery is a widely used resource. The NCI-60 has been characterized pharmacologically and at the molecular level more extensively than any other set of cell lines. However, no systematic mutation analysis of genes causally implicated in oncogenesis has been reported. This study reports the sequence analysis of 24 known cancer genes in the NCI-60 and an assessment of 4 of the 24 genes for homozygous deletions. One hundred thirty-seven oncogenic mutations were identified in 14 (APC, BRAF, CDKN2, CTNNB1, HRAS, KRAS, NRAS, SMAD4, PIK3CA, PTEN, RB1, STK11, TP53, and VHL) of the 24 genes. All lines have at least one mutation among the cancer genes examined, with most lines (73%) having more than one. Identification of those cancer genes mutated in the NCI-60, in combination with pharmacologic and molecular profiles of the cells, will allow for more informed interpretation of anticancer agent screening and will enhance the use of the NCI-60 cell lines for molecularly targeted screens.
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PMID:Mutation analysis of 24 known cancer genes in the NCI-60 cell line set. 1708 37

Gene silencing through aberrant CpG island methylation is a frequent epigenetic defect in hepatocellular carcinoma (HCC). However, nothing is known as yet whether aberrant hypermethylation occurs already in non-neoplastic liver cells from patients with hereditary haemochromatosis who have a clearly elevated risk for developing HCC. Therefore, quantitative real-time PCR-based methylation analysis of six genes frequently hypermethylated in HCC (RASSF1A, cyclinD2, p16(INK4a), GSTpi1, SOCS-1, APC) was performed for liver biopsies from patients with hereditary haemochromatosis. For genotyping of the HFE gene restriction enzyme analysis and Pyrosequencing were used. Transcriptional repression of hypermethylated genes was assessed using real-time RT-PCR. Eighty-four percent of all samples with severe hepatic iron overload and a mutated HFE gene (but without HCC) had at least one gene hypermethylated. All six genes tested were affected by aberrant hypermethylation, albeit to a different extent: RASSF1A 55%, cyclinD2 45%, p16(INK4a) 32%, GSTpi1 10%, SOCS-1 6%, APC 8%. Concomitant transcriptional down-regulation was shown for RASSF1A, cyclinD2, GSTpi1 and SOCS-1. Biopsies from haemochromatosis patients showed significantly more aberrant hypermethylation than normal liver tissue or benign liver tumours (P < 0.001) and also to a higher degree. This effect is independent of patient age, cirrhosis or hepatitis infection. This is the first report demonstrating that longstanding severe iron overload is frequently associated with epigenetic defects characteristic of HCC, which reflects the increased risk of these lesions to progress to HCC. Thus, changes in DNA methylation patterns are an early event preceding morphological alterations of malignant transformation and represent promising targets for early detection.
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PMID:Epigenetic defects of hepatocellular carcinoma are already found in non-neoplastic liver cells from patients with hereditary haemochromatosis. 1741 60

Colorectal cancer is the second leading cause of death in Hungary as well as in the developed countries. The high cancer prevalence of the gastrointestinal tract is the result of the rapid turnover of epithelial cells and exposure to dietary toxins. Adult stem cells are in the lime-light of the medicine. The adult stem cells and tumor cells resemble to each other on the basis of their properties, like self-renewal and proliferation. Cancer is believed to be a disease of stem cells. Recent years have seen major advances in our understanding of location (niche), life cycle, regulation (Wnt/beta-catenin signaling pathway) and markers (mathusashi-1, beta-catenin) of gastrointestinal stem cells. The exact role of adult stem cells in intestinal carcinogenesis is open for debate. New works suggest the role for inflammation-induced engraftment of circulating marrow-derived stem cells in colorectal carcinogenesis. The causes of malignant transformation of local or engrafting bone marrow-derived stem cells are mutations (APC, MMR genes) or methylation (CDKN2A, p16/INK4a, MGMT, MLH1). The spread of dysplastic cells (bottom-up, top-down hypothesis) is also ambiguous.
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PMID:[Stem cell theory of colorectal cancer and its connection with molecular-biological data]. 1745 7

Aberrant promoter methylation represents a main mechanism of tumor suppressor gene inactivation and may serve as a new source for biomarker discovery. This study investigated its applicability as a molecular tool for lung cancer diagnostics on bronchial aspirates. A methylation assay was developed applying a quantitative methylation specific real-time PCR (QMSP). A total of 552 patients with the differential diagnosis of lung cancer were investigated. The QMSP findings on bronchial aspirates were compared with the methylation status of respective genes investigated in microdissected tumor tissues (QMSP, cloning and sequencing of promoter regions after bisulfite conversion). Among the genes tested a marker panel consisting of APC, p16(INK4a) and RASSF1A proved to be the best suited for lung cancer diagnostics. This panel allowed for a correct diagnosis of lung cancer in cases with an ambiguous or false negative conventional cytology. In a cohort study on 247 patients, the combination of histology (sensitivity 59 %), cytology (sensitivity 44 %) and QMSP-assay (sensitivity 53 %) raised the sensitivity of a single bronchoscopy for the diagnosis of lung cancer up to 81%. The methylation assay yielded its major diagnostic surplus with respect to peripheral tumors representing 59 % of all primaries detected. In patients without antecedent lung cancer its specificity considering malignancy was >99 %. Therefore, the QMSP-assay is a promising technique which could enhance the sensitivity and diagnostic impact of conventional cytology. The assay is applicable to residual material of regular diagnostic cytology even in retrospect.
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PMID:[Aberrant promoter methylation as biomarker for molecular cytological diagnosis of lung cancer]. 1786

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Little is known about its molecular pathogenesis and the relevance of DNA methylation for disease initiation and progression. Nevertheless, promoter methylation of some genes has been implicated as potential marker for HCC. Thirty-four HCC, 34 matching non-malignant, cirrhotic livers and 16 normal livers were analyzed for the methylation status of the genes p16(INK4a), GSTP1, MGMT, DAP-K and APC by quantitative methylation-specific PCR. DNA promoter methylation frequencies in HCC and matching non-malignant cirrhotic liver, respectively, were as follows: p16(INK4a) (76% vs. 24%), GSTP1 (53% vs. 32%), MGMT (6 vs. 12%), DAP-K (68 vs. 100%) and APC (100 vs. 100%). GSTP1 and/or p16(INK4a) promoter methylation was observed in 88% of the HCC samples. In normal liver tissue, the p16(INK4a), GSTP1 and MGMT promoter were not methylated. DAP-K was methylated in 31% and APC even in 100% of normal liver samples. Quantitative levels of methylated promoter DNA of all genes were significantly different in the various tissue types except for MGMT. Our results suggest that promoter methylation of tumor-associated genes is a common event in hepatocarcinogenesis. Significantly, higher levels and frequencies of promoter methylation in HCC were found for p16(INK4a) and GSTP1 compared to non-malignant cirrhotic liver. This indicates that these epigenetic events may serve as a good marker for HCC. These data also demonstrate the importance of the quantification of methylated promoter DNA within a given sample and the use of normal tissue as controls. Quantitative analyses of methylated GSTP1 and p16(INK4a) promoter may serve as a powerful molecular marker in detecting HCC in biopsies.
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PMID:Quantitative promoter methylation analysis of hepatocellular carcinoma, cirrhotic and normal liver. 1835 80

Sporadic colorectal cancer (SCRC) occurring in young patients represent a subset with a higher proportion of advanced tumors and a poor prognosis, however, the genetic basis of SCRCs has not yet been sufficiently studied. We assigned 16 SCRC patients aged 40 years or less to group 1, and 30 SCRCs patients aged 65 years or more to group 2. The methylation status in the promoter of 7 tumor suppressor genes regarding these two groups was then examined. The average number of hypermethylated tumor-related genes per sample in group 1 was 1.50 +/- 0.07, which was significantly lower than that in group 2 of 2.73 +/- 1.24 (p = 0.0040). The frequencies of the promoter hypermethylation of hMLH1, p15INK4b, p16INK4a, and RASSF1A in group 1 were 12.5%, 12.5%, 12.5%, 6.3%, and 0.0%, which were substantially less frequent than those same rates observed in group 2. In contrast, the frequencies of the promoter hypermethylation of APC, MGMT, p14ARF, in group 1 were 43.8%, 37.5%, and 31.3%, which were as frequent as those seen in group 2. The promoter hypermethylation of APC, MGMT, and pl4ARF is therefore considered to be closely related to the development of SCRCs in young patients, regardless of aging.
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PMID:Promoter hypermethylation of tumor-related genes in sporadic colorectal cancer in young patients. 1836 48

Our understanding of somatic alterations in colon cancer has evolved from a concept of a series of events taking place in a single sequence to a recognition of multiple pathways. An oncogenetic tree is a model intended to describe the pathways and sequence of somatic alterations in carcinogenesis without assuming that tumors will fall in mutually exclusive categories. We applied this model to data on colon tumor somatic alterations. An oncogenetic tree model was built using data on mutations of TP53, KRAS2, APC, and BRAF genes, methylation at CpG sites of MLH1 and TP16 genes, methylation in tumor (MINT) markers, and microsatellite instability (MSI) for 971 colon tumors from a population-based series. Oncogenetic tree analysis resulted in a reproducible tree with three branches. The model represents methylation of MINT markers as initiating a branch and predisposing to MSI, methylation of MHL1 and TP16, and BRAF mutation. APC mutation is the first alteration in an independent branch and is followed by TP53 mutation. KRAS2 mutation was placed a third independent branch, implying that it neither depends on, nor predisposes to, the other alterations. Individual tumors were observed to have alteration patterns representing every combination of one, two, or all three branches. The oncogenetic tree model assumptions are appropriate for the observed heterogeneity of colon tumors, and the model produces a useful visual schematic of the sequence of events in pathways of colon carcinogenesis.
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PMID:Oncogenetic tree model of somatic mutations and DNA methylation in colon tumors. 1876 47


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