UMLS:C0596263 - FACTA Search

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Query: UMLS:C0596263 (carcinogenesis)
64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acrolein, an alpha,beta-unsaturated aldehyde, is by far the strongest electrophile present in cigarette smoke which is involved in several lung pathophysiological conditions. Acrolein depletes glutathione and creates thiol imbalance. Acrolein due to thiol imbalance as well as covalent modification of cysteine is known to inhibit the activity of redox sensitive transcription factors such as NF-kappaB and AP-1. Exposure of human type II lung epithelial (A549) cells to non-lethal dose of acrolein (150 fmol/cell for 1 h) depletes 80% of intracellular glutathione and increases the transcription of gamma-glutamylcysteine synthetase (gamma-GCS) at 6-12 h post-treatment, which helps in replenishing the glutathione to normal level. Acrolein treatment activates transcription of phase II genes in general, as indicated by an increase in mRNA for NAD (P) H:quinone oxidoreductase (NQO1). Western blot analysis revealed the increased level of the transcription factor, Nrf2 in the nuclear extract from acrolein treated cells. Electrophoretic mobility shift assay shows increased binding of nuclear proteins to human antioxidant response element (ARE) consensus sequence after treatment with acrolein. The involvement of Nrf2 in ARE mediated transcriptional activation in response to acrolein exposure has been confirmed by human NQO1-ARE reporter assay. The ability of acrolein to transcriptionaly activate genes responsible for phase II enzymes may form the basis of resistance against cell death and can have implications in cigarette smoke related lung carcinogenesis.
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PMID:Acrolein causes transcriptional induction of phase II genes by activation of Nrf2 in human lung type II epithelial (A549) cells. 1208 17

Electrophiles formed during metabolic activation of chemical carcinogens and reactive oxygen species generated from endogenous and exogenous sources play a significant role in carcinogenesis. Cancer chemoprevention by induction of phase 2 proteins to counteract the insults of these reactive intermediates has gained considerable attention. Nuclear factor E2 p45-related factor 2 (Nrf2), a bZIP transcription factor, plays a central role in the regulation (basal and or inducible expression) of phase 2 genes by binding to the "antioxidant response element" in their promoters. Identification of novel Nrf2-regulated genes is likely to provide insight into cellular defense systems against the toxicities of electrophiles and oxidants and may define effective targets for achieving cancer chemoprevention. Sulforaphane is a promising chemopreventive agent that exerts its effect by strong induction of phase 2 enzymes via activation of Nrf2. In the present study, a transcriptional profile of small intestine of wild-type (nrf2 +/+) and knock out (nrf2 -/-) mice treated with vehicle or sulforaphane (9 micromol/day for 1 week, p.o.) was generated using the Murine Genome U74Av2 oligonucleotide array (representing approximately 6000 well-characterized genes and nearly 6000 expressed sequence tags). Comparative analysis of gene expression changes between different treatment groups of wild-type and nrf2-deficient mice facilitated identification of numerous genes regulated by Nrf2 including previously reported Nrf2-regulated genes such as NAD(P)H:quinone reductase (NQO1), glutathione S-transferase (GST), gamma-glutamylcysteine synthetase (GCS), UDP-glucuronosyltransferases (UGT),epoxide hydrolase, as well as a number of new genes. Also identified were genes encoding for cellular NADPH regenerating enzymes (glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and malic enzyme), various xenobiotic metabolizing enzymes, antioxidants (glutathione peroxidase, glutathione reductase, ferritin, and haptaglobin), and biosynthetic enzymes of the glutathione and glucuronidation conjugation pathways. The data were validated by Northern blot analysis and enzyme assays of selected genes. This investigation expands the horizon of Nrf2-regulated genes, highlights the cross-talk between various metabolic pathways, and divulges the pivotal role played by Nrf2 in regulating cellular defenses against carcinogens and other toxins.
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PMID:Identification of Nrf2-regulated genes induced by the chemopreventive agent sulforaphane by oligonucleotide microarray. 1223 84

Human exposure to arsenic, a ubiquitous and toxic environmental pollutant, is associated with an increased incidence of skin cancer. However, the mechanism(s) associated with AsIII-mediated toxicity and carcinogenesis at low levels of exposure remains elusive. Aberrations in cell proliferation, oxidative damage, and DNA-repair fidelity have been implicated in sodium arsenite (AsIII)-mediated carcinogenicity and toxicity, but these events have been examined in isolation in the majority of biological models of arsenic exposure. We hypothesized that the simultaneous interaction of these effects may be important in arsenic-mediated neoplasia in the skin. To evaluate this, normal human epidermal keratinocytes (NHEK) were exposed to nontoxic doses (0.005-5 micro M) of AsIII and monitored for several physiological endpoints at the times when cells were harvested for gene expression measurements (1-24 h). Two-fluor cDNA microarray analyses indicated that AsIII treatment decreased the expression of genes associated with DNA repair (e.g., p53 and Damage-specific DNA-binding protein 2) and increased the expression of genes indicative of the cellular response to oxidative stress (e.g., Superoxide dismutase 1, NAD(P)H quinone oxidoreductase, and Serine/threonine kinase 25). AsIII also modulated the expression of certain transcripts associated with increased cell proliferation (e.g., Cyclin G1, Protein kinase C delta), oncogenes, and genes associated with cellular transformation (e.g., Gro-1 and V-yes). These observations correlated with measurements of cell proliferation and mitotic measurements as AsIII treatment resulted in a dose-dependent increase in cellular mitoses at 24 h and an increase in cell proliferation at 48 h of exposure. Data in this manuscript demonstrates that AsIII exposure simultaneously modulates DNA repair, cell proliferation, and redox-related gene expression in nontransformed, normal NHEK. It is anticipated that data in this report will serve as a foundation for furthering our knowledge of AsIII-regulated gene expression in skin and other tissues and contribute to a better understanding of arsenic toxicity and carcinogenesis.
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PMID:Coordination of altered DNA repair and damage pathways in arsenite-exposed keratinocytes. 1237 79

The clinical management of pancreatic disease is often hampered by a lack of tissue diagnosis. Endoscopic pancreatography offers the opportunity to investigate exfoliated cells. However, the significance of mere cytological investigation is compromised by an insufficient sensitivity. The evaluation of the molecular background of carcinogenesis hopefully is capable of providing more sensitive diagnostic markers. The p16INK4a-/retinoblastoma tumour-suppressive pathway has been shown to be involved in the development of near to all pancreatic neoplasms. p14ARF is another tumour suppressor located in the immediate neighbourhood of p16INK4a. Promoter methylation has been demonstrated to be a major inactivating mechanism of both genes. We sought to further evaluate the role of the gene locus INK4a methylation status in the endoscopic differentiation of chronic inflammatory and neoplastic pancreatic disease. Pancreatic fluid specimens of 61 patients with either pancreatic carcinoma (PCA: 39), chronic pancreatitis (CP: 16) or a normal pancreatogram (NAD: 6) were retrieved. In order to detect methylation of either the p14ARF or the p16INK4a promoter a methylation-specific PCR protocol was applied. While 19 out of 39 patients with PCA showed p16 promoter methylation (49%), none of the 16 patients with CP revealed p16 promoter methylation. p14ARF methylation was found in a lower percentage of PCA specimens and in none of the samples of patients with CP. These results suggest a specific significance of INK4a for the development of malignant pancreatic disease. Our data further indicate a potential role for INK4a methylation as a diagnostic marker in the endoscopic differentiation of benign and malignant pancreatic disease.
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PMID:Methylation status of p14ARF and p16INK4a as detected in pancreatic secretions. 1261 May 6

Identification and use of effective cancer chemopreventive agents have become an important issue in public health-related research. For identification of potential cancer chemopreventive constituents we have set up a battery of cell- and enzyme-based in vitro marker systems relevant for prevention of carcinogenesis in vivo. These systems include modulation of drug metabolism (inhibition of Cyp1A activity, induction of NAD(P)H:quinone reductase (QR) activity in Hepa1c1c7 murine hepatoma cell culture), determination of radical scavenging (DPPH scavenging) and antioxidant effects (scavenging of superoxide anion-, hydroxyl- and peroxyl-radicals), anti-inflammatory mechanisms (inhibition of lipopolysaccharide (LPS)-mediated nitric oxide (NO) generation by inducible NO synthase (iNOS) in Raw 264.7 murine macrophages, cyclooxygenase-1 (Cox-1) inhibition), and anti-tumor promoting activities (inhibition of phorbol ester-induced ornithine decarboxylase (ODC) activity in 308 murine keratinocytes). We have tested a series of known chemopreventive substances belonging to several structural classes as reference compounds for the identification of novel chemopreventive agents or mechanisms. These include organosulfur compounds (phenethylisothiocyanate (PEITC), diallylsulfide, diallyldisulfide), terpenes (limonene, perillyl alcohol, oleanolic acid, 18-beta-glycyrrhetinic acid), short-chain fatty acids (sodium butyrate), indoles (indole-3-carbinol), isoflavonoids (quercetin, silymarin, genistein), catechins ((-)-epigallocatechin gallate (EGCG)), simple phenols (ellagic acid, resveratrol, piceatannol, curcumin), pharmaceutical agents (piroxicam, acetylsalicylic acid, tamoxifen), and vitamins/derivatives (ascorbic acid, Trolox). We confirmed known chemopreventive mechanisms of these compounds. Additionally, we could demonstrate the usefulness of our approach by identification of hitherto unknown mechanisms of selected agents. As an example, we detected anti-inflammatory properties of PEITC, based on NF-kappaB-mediated inhibition of NO production. Further, PEITC inhibited phorbol ester-induced superoxide anion radical production in granulocytes, and ODC induction in the 308 cell line. These mechanisms might contribute to the chemopreventive potential of PEITC.
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PMID:Mechanism-based in vitro screening of potential cancer chemopreventive agents. 1262 14

NAD(P)H: quinone oxidoreductase 1 (NQO1) is an antioxidant enzyme, important in the detoxification of environmental carcinogens. A single base substitution (C --> T) polymorphism at nucleotide 609 (null-allele) of NQO1 gene impairs stability and function of the NQO1 protein. To investigate the association of this NQO1 polymorphism with susceptibility to esophageal squamous cell carcinoma (ESCC), the NQO1 C609T genotypes were determined by PCR-RFLP analysis in 450 patients with ESCC (257 German Caucasians and 193 northern Chinese) and 393 unrelated healthy controls (252 German Caucasians and 141 northern Chinese). Additionally, NQO1 protein expression was determined by immunohistochemistry in a subset of 74 ESCC (50 German, 24 Chinese). A significant difference in NQO1 C609T genotype distribution was observed between Caucasian healthy controls (C/C, 73.4%; C/T, 25.0%; T/T, 1.6%) and Chinese healthy controls (C/C, 34.0%; C/T, 49.7%; T/T, 16.3%) (chi(2) = 68.40, P < 0.001). The NQO1 T/T genotype significantly increased the risk for developing ESCC in both Caucasian subjects (OR = 4.62, 95% CI = 1.54-13.86) and Chinese subjects (OR = 1.81, 95% CI = 1.04-3.15), compared with the combined C/C and C/T genotypes. In Chinese subjects, this increased susceptibility was pronounced in patients with family history of upper gastrointestinal cancers (OR = 2.18, 95% CI = 1.14-4.17). Immunohistochemical analysis showed NQO1 protein expression in 53 carcinomas, whereas 21 carcinomas were negative. Negativity for NQO1 expression correlated strongly with the NQO1 genotype, being present in 8.6% of cases with C/C, 22.2% of cases with C/T and 100% of cases with T/T genotype (chi(2) = 16.60, P < 0.001). In summary, the association of the NQO1 C609T polymorphism with ESCC in genetically distinct populations makes a strong argument for its importance in carcinogenesis of ESCC in the German Caucasian and the northern Chinese population.
Carcinogenesis 2003 May
PMID:Association of NAD(P)H: quinone oxidoreductase 1 (NQO1) C609T polymorphism with esophageal squamous cell carcinoma in a German Caucasian and a northern Chinese population. 1277 Oct 35

Detoxification of ethanol can contribute to oxidative cellular and DNA damage and, thereby, to carcinogenesis. The potential relevance of this to breast carcinogenesis is suggested by evidence that alcohol consumption is a risk factor for breast cancer. It is, however, not known whether ethanol can be metabolized in breast parenchyma. The goal of this study was to determine whether class I and/or IV alcohol dehydrogenase (ADH), medium chain ADHs that can catalyze oxidation of ethanol, are expressed in human breast parenchyma. Normal and neoplastic human breast tissue specimens were examined for class I and IV ADH mRNA by reverse transcription-PCR, for protein by immunocytochemistry and Western analysis, and for their potential to catalyze NAD(+)-dependent oxidation of ethanol. Together, the findings provide evidence that: (a) class I ADH is the medium-chain ADH that is expressed in human breast parenchyma, specifically in the mammary epithelium; (b) human breast parenchyma can support ADH-mediated oxidation of ethanol; and (c) the expression of class I ADH is dramatically reduced or abrogated in invasive breast cancers. Expression of class I ADH in normal human breast parenchyma was confirmed by probing a multiple human tissue polyA(+)RNA. The unexpected finding of virtual abrogation of expression of class I ADH in invasive breast cancer suggests that the enzyme has some "tumor suppressor" function in the mammary epithelium. The one property of class I ADH fitting this designation is its potential to catalyze the oxidation of the micronutrient/prohormone retinol to retinal, the first step in the biosynthesis of retinoic acid, the principal known mediator of the actions of retinoids important for maintaining epithelia in a differentiated state.
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PMID:Class I alcohol dehydrogenase is highly expressed in normal human mammary epithelium but not in invasive breast cancer: implications for breast carcinogenesis. 1281 Jun 34

Phase II detoxifying enzymes like NAD(P)H (quinone acceptor)oxidoreductase1 (NQO1), glutathione S-transferases (GST), and UDP-glucuronyltransferases (UGT) may play an important role in preventing carcinogen-induced cancers. Inducers of these enzymes have been shown to inhibit carcinogen-induced colon tumors in rat and mouse models. However, it has not been clearly demonstrated that NQO1 contributes to this effect. We examined the effect of NQO1 inducers on colon carcinogenesis using an aberrant crypt foci (ACF) rat model. Sprague-Dawley rats were fed control diet or diet containing 400 ppm dimethyl fumarate or 200 ppm oltipraz for 7 days, and Phase II enzymes in rat colon and liver were measured. Dimethyl fumarate significantly increased NQO1 and GST activities in colon and liver but did not increase UGT activities in these tissues. In contrast, oltipraz significantly increased NQO1 activities in colon and liver and produced a small increase in GST activity in the liver but did not increase GST activity in the colon or UGT activities in the liver or colon. Sprague Dawley rats were fed control diet or diet containing 200 ppm oltipraz and then treated with the carcinogens azoxymethane or methyl nitrosourea. Both carcinogens produced ACF in all of the rat colons, but rats fed oltipraz diet had significantly fewer ACF than those fed control diet. This protective effect was reversed in rats treated with the NQO1 inhibitor, dicoumarol. However, treatment with oltipraz did not alter the distribution of crypt multiplicities in the ACF. These studies demonstrated that induction of NQO1 plays a significant role in inhibiting initiation of carcinogen-induced ACF in Sprague-Dawley rats. This provides the first direct evidence that NQO1 may play a role in preventing colon cancer. The study also found that oltipraz added to the diet of Sprague-Dawley rats selectively increased NQO1 activity in colon mucosa with no increase in GST and UGT activities in these tissues. Thus, this model will be useful for further investigating the role of NQO1 in prevention of colon cancer.
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PMID:Induction of NAD(P)H quinone: oxidoreductase1 inhibits carcinogen-induced aberrant crypt foci in colons of Sprague-Dawley rats. 1281 4

Ecto-nucleotide pyrophosphatase/phospho-diesterase-I enzyme (E-NPP), one of the type II transmembrane proteins, cleaves phosphodiester and phosphosulfate bonds of a variety of substrates including deoxynucleotides, NAD, and nucleotide sugars. Mammalian E-NPP consists of three closely related family proteins; E-NPP1 (PC-1), E-NPP2 (PDNP2/PD-Ialpha/autotaxin), and E-NPP3 (CD203c/PDNP3/PD-Ibeta/B10/gp130RB13-6) that express in different cells or at different locations even in the same cell. E-NPP3 is associated with malignant subversion and invasive properties. In this study, the expression and localization of E-NPP3 were investigated in human colon carcinoma. Western blotting showed strong E-NPP3 expression in cancer tissues and in the serum of colon carcinoma patients. Immunohistochemically, E-NPP3 was expressed not only in the apical but also in the basolateral plasma membranes of cancer cells. No prominent pattern of intracellular localization, and no relation between clinical stage and E-NPP3 expression were observed. Our results suggested that E-NPP3 is associated with carcinogenesis of human colon cancer and that serum E-NPP3 might be a tumor marker of colon carcinoma.
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PMID:Expression and localization of ecto-nucleotide pyrophosphatase/phosphodiesterase I-3 (E-NPP3/CD203c/PD-I beta/B10/gp130RB13-6) in human colon carcinoma. 1453 6

Estradiol (E2) has been linked to both, protection against damage associated with chronic diseases or exposure to chemicals, and to the incidence of cancer. In its protective role, E2 appears to attenuate oxidative stress while as a carcinogen, E2 damages macromolecules via formation of reactive catechol metabolites. Alterations in the expression of antioxidant and xenobiotic metabolizing enzymes upon administration of pharmacological doses of E2 have been previously identified, but the effect of chronic exposure to low concentrations of E2 on activities of those enzymes in liver is unclear. The August-Copenhagen Irish (ACI) rat is more sensitive to estrogen-induced carcinogenesis than the Sprague-Dawley rat. Accordingly, the effect of treatment of female ACI and Sprague-Dawley rats for 6 weeks with E2 on activities of NAD(P)H quinone oxidoreductase 1 (NQO1), glutathione peroxidase, glutathione S-transferase (GST), phenol sulfotransferase (SULT1A1), cytochrome P450 (CYP450) and UDP-glucuronosyltransferase (UGT) was studied. Basal expression of these enzymes was similar in livers from both strains prior to exposure to E2. However, only NQO1 and GST activity was increased (3- and 2.5-fold, respectively) in liver cytosol of ACI rats treated with E2. In contrast, only NQO1 activity was increased modestly in livers of Sprague-Dawley rats. Other enzymes were not significantly affected in the livers of ACI or Sprague-Dawley rats following chronic treatment with E2. The selective induction of NQO1 and GST activity suggests that under physiological conditions, E2 may protect against oxidative stress via elevation of these antioxidant enzymes. The marked induction of NQO1 and GST in the ACI rat indicates a potential for this strain to be used as a model to study the E2-mediated modulation of these enzymes in tissues that are either sensitive to E2 carcinogenesis or to its protective effects.
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PMID:Induction of NAD(P)H quinone oxidoreductase and glutathione S-transferase activities in livers of female August-Copenhagen Irish rats treated chronically with estradiol: comparison with the Sprague-Dawley rat. 1467 40

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