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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-terminal methionine removal is an important cellular process required for proper biological activity, subcellular localization, and eventual degradation of many proteins. The enzymes that catalyze this reaction are called Methionine Aminopeptidases (MAPs). To date, only two MAP family members, MAP1A and MAP2, have been well characterized and studied in mammals. In our studies, we have cloned a full length MAP1D gene. Expression and purification of full length recombinant protein shows that the sequence encodes an enzyme with MAP activity. MAP1D is overexpressed in colon cancer cell lines and in colon tumors as compared to matched normal tissue samples. Downregulation of MAP1D expression by shRNA in HCT-116 colon carcinoma cells reduces anchorage-independant growth in soft agar. These data suggest that MAP1D is a potentially oncogenic, novel member of the MAP gene family that may play an important role in colon tumorigenesis.
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PMID:MAP1D, a novel methionine aminopeptidase family member is overexpressed in colon cancer. 1656 94

The folate antagonist methotrexate (MTX) inhibits synthesis of tetrahydrofolate (THF), pyrimidines and purines, and induces differentiation in several cell types. At 1 microM, MTX reduced proliferation and induced differentiation in HT29 colon cancer cells; the latter effect was augmented (P < 0.001) by thymidine (100 microM) but was reversed (P < 0.001) by the purines, hypoxanthine (Hx; 100 microM) and adenosine (100 microM). In contrast 5-fluoro-uracil (5-FU), a specific thymidylate synthase (TS) inhibitor, had no effect on differentiation, suggesting that MTX-induced differentiation is not due to a reduction in thymidine but to the inhibition of purine biosynthesis. Inhibition of cyclic AMP (cAMP) by RpcAMP (25 microM) further enhanced (P < 0.001) MTX induced differentiation, whereas the cAMP activator forskolin (10 microM) reversed (P < 0.001) MTX induced differentiation. These observations implicate a central role of adenosine and cAMP in MTX induced differentiation. By combining Western blot analysis with liquid chromatography-mass spectrometry (LC-MS)and HPLC analyses we also reveal both the expression and activity of key enzymes (i.e. methionine synthase (MS), s-adenosylhomocysteinase, cystathionine beta-synthase and ornithine decarboxylase) regulating methyl cycle, transsulfuration and polyamine pathways in HT29 colon cancer cells. At 1 microM, MTX induced differentiation was associated with a marked reduction in the intracellular concentrations of adenosine and, consequently, S-adenosylmethionine (SAM), S-adenosylhomocysteine, polyamines and glutathione (GSH). Importantly, the marked reduction in methionine that accompanied MS inhibition following MTX treatment was non-limiting with respect to SAM synthesis. Collectively, these findings indicate that the effects of MTX on cellular differentiation and single carbon metabolism are primarily due to the intracellular depletion of purines.
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PMID:Methotrexate induced differentiation in colon cancer cells is primarily due to purine deprivation. 1659 58

Fibrinogen is a major plasma protein (350 kDa) that induces proliferative signals by serving as a scaffold to support the binding of growth factors and to promote the cellular responses of adhesion, proliferation, and migration during wound healing, angiogenesis, and tumor growth. Fibrin(ogen) degradation products generated during fibrinolysis are implicated in tissue injury. The fibrinogen gamma chain has a COOH-terminal globular domain (gamma C, residues 151-411 of the gamma chain, 30 kDa) to which several integrin cell adhesion receptors (e.g., platelet alpha(IIb)beta(3), endothelial alpha(v)beta(3), and leukocyte alpha(M)beta(2)) bind. Integrins play a critical role in signal transduction from fibrin(ogen). We found that gamma C and its truncation mutant (designated gamma C399tr), with a deletion of the COOH-terminal 12 residues, induced apoptosis of endothelial cells and blocked tube formation of endothelial cells. DLD-1 human colon cancer cells that secrete gamma C or gamma C399tr grew at similar levels in vitro but grew much slower in vivo than mock-transfected cells. The recombinant purified gamma C399tr fragment markedly suppressed tumor growth, development of intratumoral vasculature, and tumor metastasis in vivo in the highly metastatic Met-1 breast cancer model. The determinant responsible for binding to endothelial cells is cryptic in native fibrinogen but is exposed in gamma C and gamma C399tr. These results suggest that fibrinogen has a novel cryptic determinant, which can exert apoptosis-inducing activity on endothelial cells when exposed, and polypeptides containing this determinant have therapeutic potential.
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PMID:The COOH-terminal globular domain of fibrinogen gamma chain suppresses angiogenesis and tumor growth. 1701 27

It has been proposed that dietary factors such as folate, alcohol and methionine may be associated with colon cancer because of their involvement in DNA methylation processes. Data from a large population-based case-control study of incident colon cancer were used to evaluate whether intake of dietary, obesity, physical activity and nonsteroidal antiinflammatory drugs are associated with a CpG island methylator phenotype (CIMP). The BRAF V600E mutation and 5 CpG island markers (MINT1, MINT2, MINT31, p16 and hMLH1) were assessed in 1154 cases of colon cancer. We hypothesized that dietary factors involved in DNA methylation, cruciferous vegetables and use of aspirin/NSAIDs would be associated with CIMP-high tumors. Dietary folate, vitamins B(6) and B(12), methionine and alcohol were not associated with increased likelihood of colon tumors with the CIMP-high (2 or more markers methylated) phenotype. Dietary fiber, physical activity and aspirin and other nonsteroidal antiinflammatory drugs were inversely associated with both CIMP-low and CIMP-high tumors. Our results also suggested non-CIMP pathways as well. Obese individuals were at 2-fold increased risk of having a CIMP-low tumor. Alcohol was associated with an increased risk of tumors that were MSI+ and CIMP-low. In the presence of smoking 20 or more cigarettes per day, use of NSAIDs did not protect against a BRAF mutation. Our data suggest multiple pathways to colon cancer. They do not support a unique role for dietary folate, alcohol, vitamins B(6) and B(12) and methionine in a CpG island methylator phenotype.
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PMID:Diet and lifestyle factor associations with CpG island methylator phenotype and BRAF mutations in colon cancer. 1709 26

The data reported here were obtained from the case-control arm of a large, comprehensive, population-based investigation of colorectal cancer incidence, etiology, and survival, the Melbourne Colorectal Cancer Study, conducted in Melbourne, Australia. This part of the case-control study was designed to identify dietary factors associated with colorectal cancer risk in 715 incident cases compared with 727 age/sex frequency-matched randomly chosen community controls, in which a quantitative assessment of all foods eaten was made. New data are presented on the potential of two groups of micronutrients as protective agents, namely, those involved in DNA methylation, synthesis, and repair (folate, methionine, and vitamins B6 and B12) and those with antioxidant properties (selenium, vitamins E and C, and lycopene). The adjusted odds ratios showed that for folate there was significant protection for rectal cancer in second and third quintiles of consumption but not for colon cancer, and this was similar for methionine consumption. Vitamin B6 consumption was significantly protective for both colon and rectal cancer at the higher quintiles, and this was similar for vitamin B12. Dietary selenium was significantly protective at middle quintiles of consumption at both cancer sites. Dietary vitamins E and C were statistically significantly protective for both colon and rectal cancer at all levels of consumption, and for both vitamins there was a dose-response effect of increasing protection, particularly so for colon cancer. Lycopene was not associated with colorectal cancer risk. A combined model included vitamins E, C, and B12 and selenium as micronutrients protective for colorectal cancer and folate, which, however, showed an increased risk at the highest level of consumption. These data support the proposition that a diet containing the dietary micronutrients involved in DNA methylation (folate, methionine, and vitamins B6 and B12) and some of those with antioxidant properties (selenium and vitamins E and C) may have a role to play in lowering colorectal cancer risk and also that such protection can be achieved by dietary means alone.
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PMID:Colorectal cancer protective effects and the dietary micronutrients folate, methionine, vitamins B6, B12, C, E, selenium, and lycopene. 1717 13

Papillary thyroid carcinoma (PTC) is the most frequent malignant neoplasm of the thyroid originating from the thyroid follicular cell (TFC). Although the formation of PTC is believed to result from rearrangements of RET or TRK oncogenes or MET point mutations, these structural aberrations or point mutations do not correlate with the clinicopathological features of PTC and do not seem to be a useful prognostic marker of the disease. Therefore, further experiments should be carried out in order to find new practical clinical markers. Recently, oncogene BRAF has become a subject of great interest. The mutation of BRAF gene is characteristic for PTC and poorly differentiated and/or undifferentiated cancers derived from PTC. The occurrence of BRAF mutation has often been observed in various human tumours. The presence of mutation was confirmed in melanoma, colon cancer, gliomas and lung cancer. In the majority of cases, there is only one type of point mutation - V600E. The RAS/RAF/MEK/MAPK kinase pathway mediates the cellular response to mitogenic signals. BRAF gene mutation results in increased kinase activity, leading to excessive activation of the above mitogenic pathway and to uncontrolled proliferation of cancer cells. Some correlation was noticed between BRAF gene mutation and the clinical stage of the neoplastic disease in question. Preliminary investigations indicate that the presence of BRAF mutation might be a valuable diagnostic and prognostic marker of the disease. Further investigations could also bring further improvements into the therapeutic management of thyroid cancer. There are reports emphasizing the possibility of using the inhibitors of BRAF proteins in the treatment of PTC. Certainly, in order to confirm the diagnostic usefulness of this marker, further studies should be carried out.
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PMID:BRAF mutations in papillary thyroid carcinoma. 1720 87

Intracellular folate homeostasis is essential for the 1-carbon transfer reactions necessary for DNA synthesis and biological methylation reactions in colonic epithelial cells. Perturbed 1-carbon transfer reactions resulting from folate depletion predispose normal colonic epithelial cells to neoplastic transformation while inhibiting the growth of colon cancer cells. Using an in vitro model of folate deficiency, we determined the effects of folate deficiency on the steady-state transcript levels of genes involved in intracellular folate metabolism and 1-carbon transfer reactions in HCT116 and Caco2 human colon adenocarcinoma cells. In HCT116 cells, folate depletion was associated with changes in transcript levels of genes favoring increased folate uptake and intracellular folate retention, the provision of metabolically more effective substrates for folate-dependent enzymes, and reduced folate hydrolysis and efflux. In HCT116 cells, folate depletion was associated with changes in transcript levels of genes favoring the preferential shuttling of the flux of 1-carbon units to the methionine cycle over the nucleotide synthesis pathway. In Caco2 cells, some adaptive responses in response to folate depletion were not as apparent as in HCT116 cells, and in some cases, the direction of change was counterintuitive. In Caco2 cells, the metabolic priority in response to folate depletion was to shuttle the available folate pools to the nucleotide biosynthesis pathway at the expense of biological methylation reactions. In both HCT116 and Caco2 cells, folate depletion was associated with the conservation of the existing pattern and extent of DNA methylation.
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PMID:Folate deficiency induces cell-specific changes in the steady-state transcript levels of genes involved in folate metabolism and 1-carbon transfer reactions in human colonic epithelial cells. 1731 48

This study investigated associations between CpG island methylator phenotype (CIMP) colon cancer and genetic polymorphisms relevant to one-carbon metabolism and thus, potentially the provision of methyl groups and risk of colon cancer. Data from a large, population-based case-control study (916 incident colon cancer cases and 1,972 matched controls) were used. Candidate polymorphisms in methylenetetrahydrofolate reductase (MTHFR), thymidylate synthase (TS), transcobalamin II (TCNII), methionine synthase (MTR), reduced folate carrier (RFC), methylenetetrahydrofolate dehydrogenase 1 (MTHFD1), dihydrofolate reductase (DHFR) and alcohol dehydrogenase 3 (ADH3) were evaluated. CIMP- or CIMP+ phenotype was based on five CpG island markers: MINT1, MINT2, MINT31, p16 and MLH1. The influence of specific dietary factors (folate, methionine, vitamin B(12) and alcohol) on these associations was also analyzed. We hypothesized that polymorphisms involved in the provision of methyl groups would be associated with CIMP+ tumors (two or more of five markers methylated), potentially modified by diet. Few associations specific to CIMP+ tumors were observed overall, which does not support the hypothesis that the provision of methyl groups is important in defining a methylator phenotype. However, our data suggest that genetic polymorphisms in MTHFR 1,298A > C, interacting with diet, may be involved in the development of highly CpG-methylated colon cancers. AC and CC genotypes in conjunction with a high-risk dietary pattern (low folate and methionine intake and high alcohol use) were associated with CIMP+ (OR = 2.1, 95% CI = 1.3-3.4 versus AA/high risk; P-interaction = 0.03). These results provide only limited support for a role of polymorphisms in one-carbon metabolism in the etiology of CIMP colon cancer.
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PMID:Genetic polymorphisms in one-carbon metabolism: associations with CpG island methylator phenotype (CIMP) in colon cancer and the modifying effects of diet. 1744 6

NK4, originally prepared as a competitive antagonist for hepatocyte growth factor (HGF), is a bifunctional molecule that acts as an HGF-antagonist and angiogenesis inhibitor. When the expression plasmid for NK4 gene was administered into mice by hydrodynamics-based delivery, the repetitive increase in the plasma NK4 protein level was achieved by repetitive administration of NK4 gene. Mice were subcutaneously implanted with colon cancer cells and weekly given with the NK4 plasmid. The repetitive delivery and expression of NK4 gene inhibited angiogenesis and invasiveness of colon cancer cells in subcutaneous tumor tissue and this was associated with suppression of primary tumor growth. By fifty days after tumor implantation, cancer cells naturally metastasized to the liver, whereas NK4 gene expression potently inhibited liver metastasis. Inhibition of the HGF-Met receptor pathway and tumor angiogenesis by NK4 gene expression has potential therapeutic value toward inhibition of invasion, growth, and metastasis of colon cancer.
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PMID:Inhibition of colon cancer growth and metastasis by NK4 gene repetitive delivery in mice. 1746 63

Much information has been reported on the genetic and genomic alterations in colorectal cancer (CRC) in literature; however, nonrandom chromosomal alterations in Chinese CRC patients have only one report in Hong Kong. To further identify genomic alteration in primary sporadic colorectal carcinomas (SCRC) in Chinese patients and understand the molecular mechanisms in CRC development, progress, and metastasis, we used comparative genomic hybridization to screen for losses and/or gains of DNA copies along chromosomes in 24 SCRC tissues from 24 patients. Comparative genomic hybridization was applied to investigate the genomic imbalance in 24 cases of primary SCRC and compared the differences between tumors in different loci and between tumors with and without metastasis. The common chromosomal alterations in the SCRC included gains of chromosomes 1q, 2q, 4q, 7q, 8q, 11q, 13q, 20q and also losses of chromosomes 9p, 16q, 17p, 18q. Among them, gains of 1q, 7q, 20q and losses of 17p, 18q were related with lymph node metastasis of SCRC (P<0.05). The gains of 4q, 7q, 20q and losses of 9p, 18q were related with the sites (P<0.05), colon and rectum, respectively; gain of 20q and loss of 9p were commonly found in the colon cancer; gain of 4q, 7q and loss of 18q were easily seen in the rectal cancer. There are multiple regions of chromosomes with copy-number changes in SCRC. The tumor suppressor genes and oncogenes on these regions may be involved in the development and progress of SCRC. The chromosome 1q, 2q, 4q, 7q, 8q, 11q, 13q, 20q regions may have oncogenes such as epidermal growth factor, MET, platelet-derived growth factor receptor A, and 9p, 16q, 17p, 18q regions may have tumor suppressor genes such as p53,DCC, IGFR1 associated with occurrence of SCRC. The chromosome 1q, 7q, 20q, 17p, 18q regions may have genes related with metastasis of SCRC. The development mechanisms of colon cancer and rectal cancer may not be completely similar. Additionally, gain of chromosome 1q was verified by the second technique-Real-time reverse transcription PCR.
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PMID:Chromosomal alteration in Chinese sporadic colorectal carcinomas detected by comparative genomic hybridization. 1752 79


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