Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

PGE(2) is a well-known immunomodulator produced in the immune response by APCs, such as dendritic cells (DCs), the most potent APC of the immune system. We investigated the PGE(2) biosynthetic capacity of bone marrow-derived DC (BM-DC) and the effects of PG on the APC. We observed that BM-DC produce PGE(2) and other proinflammatory mediators, such as leukotriene B(4) and NO, after LPS exposure. Constitutively present in BM-DC, cyclooxygenase (COX)-1 did not contribute significantly to the total pool of PGE(2) compared with the LPS-induced COX-2-produced PGE(2). Treatment of BM-DC with exogenous PGE(2) induced the production of large amounts of IL-10 and less IL-12p70. In addition, selective inhibition of COX-2, but not COX-1, was followed by significant decrements in PGE(2) and IL-10, a concomitant restoration of IL-12 production, and an enhancement of DC stimulatory potential. In contrast, we found no demonstrable role for leukotriene B(4) or NO. In view of the potential of PGE(2) to stimulate IL-10, we examined the possibility that the suppressive effect of PGE(2) is mediated via IL-10. We found that exogenous IL-10 inhibits IL-12p70 production in the presence of NS-398, a COX-2 selective inhibitor, while the inhibitory effects of PGE(2) were totally reversed by anti-IL-10. We conclude that COX-2-mediated PGE(2) up-regulates IL-10, which down-regulates IL-12 production and the APC function of BM-DC.
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PMID:Cyclooxygenase-2-issued prostaglandin e(2) enhances the production of endogenous IL-10, which down-regulates dendritic cell functions. 1185 13

To elucidate early molecular events related to colon carcinogenesis, we examined alterations in the expression of colon cancer-related genes such as cyclooxygenase (COX)-2, APC and c-Myc, cell proliferation and apoptosis in the background colon mucosa, and K-ras mutation at aberrant crypt foci (ACF) in the colons of azoxymethane (AOM)-treated rats 4 weeks after the first exposure to AOM. About 40 ACF/colon were induced in the colons of rats treated with AOM (Group 1); however, rats not treated with AOM (Group 2) showed no ACF formation in the colon. The level of AgNORs in the colonic mucosa was significantly higher in Group 1 than in Group 2 (P<0.01). The colonic mucosa in Group 1 looked macroscopically and histologically normal, but the proliferative activity of the mucosa of rats treated with AOM was clearly elevated. COX-2 mRNA expression was not detected in normal colonic mucosa in Group 2, but 3 out of 10 rats in Group 1 showed COX-2 mRNA expression in their colons by reverse transcription (RT)-polymerase chain reaction (PCR). There was a tendency toward an increased expression level of COX-2 in the AOM-treated group. The level of APC mRNA expression in Group 1 was significantly lower than that in Group 2 (P<0.01). Moreover, the level of c-Myc mRNA expression in Group 1 was significantly higher than that in Group 2 (P<0.01). An average of 0.034+/-0.006% apoptosis in colonic mucosa was detected in Group 1; the incidence of apoptosis in Group 2 was 0.021+/-0.005%. The difference between Groups 1 and 2 was significant (P<0.01). These results indicate that apoptosis was possibly induced to eliminate cells damaged by AOM administration. Six out of 22 (27%) ACF with 4 or more crypts showed K-ras mutations at codon 12; all mutations were G to A transitions (GGT to GAT). ACF with 1-3 crypts showed no mutations in the K-ras gene. In conclusion, AOM caused an increase in COX-2 and c-Myc mRNA expression, a decrease in APC mRNA expression, induction of apoptosis in normal-appearing colonic mucosa, and a K-ras mutation in ACF with 4 or more crypts. These findings may help to identify key targets in the early steps of colon carcinogenesis, against which drugs that would be broadly effective for chemoprevention of colon cancer could be developed.
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PMID:Molecular changes in the early stage of colon carcinogenesis in rats treated with azoxymethane. 1214 79

Linoleic and alpha-linolenic acids, obtained from plant material in the diet are the precursors in tissues of two families with opposing effects which are referred to as "essential fatty acids" (EFA): arachidonic acid (AA) and pentaene (eicosapentaenoic acid: EPA) and hexaene (docosahexaenoic acid: DHA) acids. The role of EFA is crucial, without a source of AA or compounds which can be converted into AA, synthesis of prostaglandins (PGs) by a cyclooxygenase (COX) enzyme would be compromised, and this would seriously affect many normal metabolic processes. COX, also known as prostaglandin endoperoxide synthase (Pghs) or as prostaglandin G/H synthase, is a key membrane bound enzyme responsible for the oxidation of AA to PGs. Two COX isoforms have been identified, COX-1 and COX-2 that form PGH2, a common precursor for the biosynthesis of thromboxane A2 (TxA2), prostacyclin (PGI2) and PGs (PGD2, PGE2, PGF2alpha. COX-1 enzyme is expressed constitutively in most cells and tissues. Its expression remains constant under either physiological or pathological conditions controlling synthesis of those PGs primarily involved in the regulation of homeostatic functions. In contrast, COX-2 is an intermediate response gene that encodes a 71-kDa protein. COX-2 is normally absent from most cells but highly inducible in certain cells in response to inflammatory stimuli resulting in enhanced PG release. PGs formed by COX-2 primarily mediate pain and inflammation but have multiple effects that can favour tumorigenesis. They are more abundant in cancers than in normal tissues from which the cancers arise. COX-2 is a participant in the pathway of colon carcinogenesis, especially when mutation of the APC (Adenomatous Polyposis Coli) tumour suppressor gene is the initiating event. In addition, COX-2 up-regulation and elevated PGE2 levels are involved in breast carcinogenesis. It seems that there is a correlation between COX-2 level of expression and the size of the tumours and their propensity to invade underlying tissue. Inhibition by non-steroidal anti-inflammatory drugs (NSAIDs) of COX enzymes which significantly suppress PGE2 levels, reduced breast cancer incidence and protected against colorectal cancer. Therefore it is suggested that consumption of a diet enriched in n-3 PUFA (specifically EPA and DHA) and inhibition of COX-2 by NSAIDs may confer cardioprotective effects and provide a significant mechanism for the prevention and treatment of human cancers.
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PMID:Polyunsaturated fatty acids (PUFA) and eicosanoids in human health and pathologies. 1219 20

Aberrant methylation of promoter CpG islands of human genes has been known as an alternative mechanism of gene inactivation and contributes to the carcinogenesis in many human tumors. We attempted to determine the methylation status of 18 genes, or loci known to be frequently methylated in cancers of other organs, in 79 resected intrahepatic cholangiocarcinomas and 15 normal bile duct epithelium by methylation-specific polymerase chain reaction and correlated the data with clinicopathological findings. Methylation frequencies of the loci tested in intrahepatic cholangiocarcinomas were 59.5% for 14-3-3sigma,26.6% for APC, 21.5% for E-cadherin, 17.7% for p16, 11.4% for MGMT, 11.4% for THBS1, 8.9% for p14, 8.9% for TIMP3, 7.6% for DAP-kinase,6.3% for GSTP1, 5.1% for COX-2, 50.6% for MINT12, 40.5% for MINT1, 15.4% for MINT25, 35.4% for MINT32, and 1.3% for MINT31. Sixty-two (78.5%) of the 79 intrahepatic cholangiocarcinomas had methylation in at least one of these loci. Methylation was not detected in normal bile duct samples. There was a significant correlation between methylation and expressional decrease or loss of p16, E-cadherin, and GSTP1 proteins (P = 0.028, P = 0.044, and P < 0.001, respectively). The overall survival was poorer in the patients with CpG island methylation of APC, p16, and TIMP3 than in the patients without methylation (Kaplan-Meier log-rank test, P = 0.0128, 0.0447, and 0.0137, respectively). Age, gender, tumor stage, gross type, histological type, and differentiation had no correlation with methylation status of the specific gene. These results suggest that methylation is a frequent event in cholangiocarcinomas and contributes to the cholangiocarcinogenesis, and that CpG island methylation of APC, p16, or TIMP-3 may serve as a potential prognostic biomarker of the cholangiocarcinomas.
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PMID:Aberrant CpG island methylation of multiple genes in intrahepatic cholangiocarcinoma. 1221 30

The stomach is one of the organs whose epithelial cells frequently undergo aberrant methylation of CpG islands. To date, several reports on the methylation of various genes in gastric cancer (GC) have been published. However, most of these studies have focused on cancer tissues or a single gene only and gave no information about the methylation status of specific genes in the premalignant stages or the concurrent methylation of other genes in specific lesions. We attempted to investigate methylation of multiple genes in a large sample collection of GC (n = 80), gastric adenoma (GA) (n = 79), intestinal metaplasia (IM) (n = 57), and chronic gastritis (CG) (n = 74). We determined the methylation frequency of 12 genes, including APC, COX-2, DAP-kinase, E-cadherin, GSTP1, hMLH1, MGMT, p16, p14, RASSF1A, THBS1, and TIMP3, by methylation-specific PCR. Five different classes of methylation behaviors were found: (a). genes methylated in GC only (GSTP1 and RASSF1A), (b). genes showing low methylation frequency (<12%) in CG, IM, and gastric adenoma (GA) but significantly higher methylation frequency in GC (COX-2, hMLH1, p16), (c). a gene with low and similar methylation frequency (8.8-21.3%) in four-step lesions (MGMT), (d). genes with high and similar methylation frequency (53-85%) in four-step lesions (APC and E-cadherin), and (e). genes showing an increasing tendency with or without fluctuation of the methylation frequency along the progression (DAP-kinase, p14, THBS1, and TIMP-3). The average number of methylated genes was 2.7, 3.6, 3.4, and 5.2 per 12 tested genes in CG, IM, GA, and GC, respectively. Aberrant methylation at multiple loci in the same lesions suggests an overall deregulation of the methylation control, which occurs early in multistep gastric carcinogenesis. Our results suggest that tumor-suppressor genes show a gene-type specific methylation profile along the multistep carcinogenesis and that aberrant CpG island methylation tend to accumulate along the multistep carcinogenesis.
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PMID:Profile of aberrant CpG island methylation along multistep gastric carcinogenesis. 1269 55

To date, several reports on methylation of various genes in gastric cancer (GC) have been published. However, most of these studies focused on cancer tissues or a single gene only and gave no information about the methylation status of specific genes in the premalignant stages or about the concurrent methylation of other genes in specific lesions. We attempted to investigate methylation of multiple genes in a large sample collection of GC (n = 80), gastric adenoma (GA) (n = 79), intestinal metaplasia (IM) (n = 57), and chronic gastritis (CG) (n = 74). We determined the methylation frequency of 12 genes, including APC, COX-2, DAP-kinase, E-cadherin, GSTP1, hMLH1, MGMT, p16, p14, RASSF1A, THBS1, and TIMP3 by methylation-specific PCR. Five different classes of methylation behaviors were found: (1) genes methylated in GC only (GSTP1 and RASSF1A); (2) genes showing low methylation frequency (<12%) in CG, IM, and GA, but significantly higher methylation frequency in GC (COX-2, hMLH1, and p16); (3) a gene with low and similar methylation frequency (8.8-21.3%) in four-step lesions (MGMT); (4) genes with high and similar methylation frequency (53-85%) in four-step lesions (APC and E-cadherin); and (5) genes showing an increasing tendency with or without fluctuation of the methylation frequency along the progression (DAP-kinase, p14, THBS1, and TIMP3). The average number of methylated genes was 2.7, 3.6, 3.4, and 5.2 per 12 tested genes in CG, IM, GA, and GC, respectively. Our results suggest that tumor suppressor genes show a gene type-specific methylation profile and that aberrant CpG island methylation tends to accumulate along the pathway of multistep carcinogenesis.
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PMID:Profile of aberrant CpG island methylation along the multistep pathway of gastric carcinogenesis. 1274 73

To determine the methylation profile of multiple tumor-related genes during multistep hepatocarcinogenesis, we investigated the methylation status of CpG islands of 9 genes, using methylation-specific polymerase chain reaction for 60 paired hepatocellular carcinoma (HCC) and non-HCC liver tissue samples, 22 dysplastic nodule (DN), 30 liver cirrhosis (LC), 34 chronic hepatitis (CH) and 20 normal liver samples. The methylation status of 9 genes was correlated to the clinicopathological findings of HCC patients. All HCC samples showed methylation of at least one gene, whereas it was shown in 72.7% of DN and 40% of LC, but was not shown in CH and normal liver samples (P < 0.001). The number of genes methylated showed a stepwise increase with the progression of stages (0 for normal liver and CH, 0.5 for LC, 1.5 for DN, and 3.7 for HCC (P < 0.001)). The genes frequently methylated in HCC were APC (81.7%), GSTP1 (76.7%), RASSF1A (66.7%), p16 (48.3%), COX-2 (35%), and E-cadherin (33.3%). COX-2, p16, RASSF1A, and TIMP-3 were not methylated in LC and CH from patients without concurrent HCC. Chronic liver diseases with concurrent HCC showed higher methylation frequencies of the tested genes, and a higher number of methylated genes than those without concurrent HCC. HCC patients with methylation of E-cadherin or GSTP1 showed poorer survival than those without (P = 0.034 and 0.043, respectively). In conclusion, our results indicated that CpG island methylation of tumor-related genes is an early and frequent event, and accumulates step-by-step during a multistep hepatocarcinogenesis. CpG island methylation of E-cadherin or GSTP1 might serve as a potential biomarker for prognostication of HCC patients.
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PMID:Aberrant CpG island hypermethylation along multistep hepatocarcinogenesis. 1450 45

Since the first detection of aberrant crypt foci (ACF) in carcinogen-treated mice, there have been numerous studies focusing on these microscopically visible lesions both in rodents and in humans. ACF have been generally accepted as precancerous lesions in regard to histopathological characteristics, biochemical and immunohistochemical alterations, and genetic and epigenetic alterations. ACF show variable histological features, ranging from hyperplasia to dysplasia. ACF in human colon are more frequently located in the distal parts than in the proximal parts, which is in accordance with those in colorectal cancer (CRC). The immunohistochemical expressions of carcinoembryonic antigen (CEA), beta-catenin, placental cadherin (P-cadherin), epithelial cadherin (E-cadherin), inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), and P16INK4a are found to be altered. Genetic mutations of K-ras, APC and p53, and the epigenetic alterations of CpG island methylation of ACF have also been demonstrated. Genomic instabilities due to the defect of mismatch repair (MMR) system are detectable in ACF. Two hypotheses have been proposed. One is the "dysplasia ACF-adenoma-carcinoma sequence", the other is "heteroplastic ACF-adenoma-carcinoma sequence". The malignant potential of ACF, especially dysplastic ACF, makes it necessary to reveal the nature of these lesions, and to prevent CRC from the earliest possible stage. The technique of magnifying chromoscope makes it possible to detect "in vivo" ACF, which is beneficial to colon cancer research, identifying high-risk populations for CRC, and developing preventive procedures.
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PMID:Aberrant crypt foci as microscopic precursors of colorectal cancer. 1466 4

Nonsteroidal anti-inflammatory drugs (NSAIDs) have chemopreventive potential against colorectal carcinomas (CRCs). Inhibition of cyclooxygenase (COX)-2 underlies part of this effect, although COX-2-independent mechanisms may also exist. Nonsteroidal anti-inflammatory drugs appear to inhibit the initial stages of the adenoma-carcinoma sequence, suggesting a link to the APC/beta-catenin/TCF pathway (Wnt-signalling pathway). Therefore, the effect of the NSAID sulindac on nuclear (nonphosphorylated) beta-catenin and beta-catenin/TCF-mediated transcription was investigated. Nuclear beta-catenin expression was assessed in pretreatment colorectal adenomas and in adenomas after treatment with sulindac from five patients with familial adenomatous polyposis (FAP). Also, the effect of sulindac sulphide on beta-catenin/TCF-mediated transcription was studied. Adenomas of FAP patients collected after treatment with sulindac for up to 6 months showed less nuclear beta-catenin expression compared to pretreatment adenomas of the same patients. Sulindac sulphide abrogated beta-catenin/TCF-mediated transcription in the CRC cell lines DLD1 and SW480, and decreased the levels of nonphosphorylated beta-catenin. As a result, the protein levels of the positively regulated TCF targets Met and cyclin D1 were downregulated after sulindac treatment. This study provides in vivo and in vitro evidence that nuclear beta-catenin localisation and beta-catenin/TCF-regulated transcription of target genes can be inhibited by sulindac. The inhibition of Wnt-signalling provides an explanation for the COX-2-independent mechanism of chemoprevention by NSAIDs.
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PMID:Sulindac targets nuclear beta-catenin accumulation and Wnt signalling in adenomas of patients with familial adenomatous polyposis and in human colorectal cancer cell lines. 1471 Feb 33

CpG island hypermethylation is a potential means of inactivating tumor suppressor genes, and many genes have been demonstrated to be hypermethylated and silenced in colorectal cancer. However, limited data is available upon the concurrent methylation of multiple genes in colorectal cancer and in its precursor lesion. To address changes in the methylation profiles of multiple genes during colorectal carcinogenesis, we investigated the methylation of 12 genes (APC, COX-2, DAP-kinase, E-cadherin, GSTP1, hMLH1, MGMT, p14, p16, RASSF1A, THBS1, and TIMP3) in normal colon (n=24), colon adenoma (n=95), and colorectal cancer (n=149), using methylation-specific PCR. The average number of these genes methylated per sample was 0.12, 1.8, and 3.0 in normal colon mucosa, adenoma, and carcinoma, respectively, showing a stepwise increase (P<0.001). All the genes were methylated in colorectal cancer at frequencies varying from 51 to 9.4% and colon adenoma displayed methylation for the 11 genes, except for GSTP1, at frequencies varying from 40 to 1.1%. In contrast, normal colon mucosa demonstrated methylation for APC only, at a frequency of 12.5%. The total number of methylated genes per tumor showed a continuous, nonbimodal distribution in colon adenoma or cancer. CpG island hypermethylation exhibited a proclivity toward proximal colon cancer or adenoma, and the average number of genes methylated was higher in proximal colon cancer or adenoma than in distal colon cancer or adenoma, respectively (3.5 vs 2.6, P=0.018 for cancer, and 2.5 vs 1.4, P=0.003 for adenoma). In conclusion, concurrent CpG island methylation is an early and frequent event during colorectal carcinogenesis. It appears that CpG island methylation plays a more important role in proximal colon cancer development than in distal colon cancer development.
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PMID:Aberrant CpG island hypermethylation of multiple genes in colorectal neoplasia. 1512 5


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