UMLS:C0699790 - FACTA Search

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

The expression of nitric oxide synthase (NOS) was studied by NAD(P)H diaphorase histochemical localization method in (i) individual cells of the normal colonic mucosa (n = 13) which served as control, (ii) colonic polyps (n = 14), (iii) colonic carcinoma (n = 20) and (iv) peritumoral mucosa (2 and 5 or 10 cm away from the tumor). Four of the tumor specimens had normal epithelium adjacent to the cancer, which thus served as an internal control. The expression of NOS activity in colon cancer was significantly reduced as compared to the control group of individuals (P < 0.004); undetectable in 25%, diminished in 45%, normal in 30%. On comparing the expression in normal mucosa and polyps there was a significant reduction of the expression in polyps (P < 0.027); undetectable in 14%, reduced in 35%, normal in 51%. When compared to the peritumoral mucosa at 2 and 10 cm the tumor showed a significant reduction in expression of NOS activity (P < 0.001 and P < 0.0001 respectively). There was no significant difference seen in the expression at 2 and 10 cm (P = 0.329). The peritumoral mucosa at a distance of 2 cm away from the tumor when compared to the control mucosa showed no significant difference (P = 1.000), although there is a tendency to a high normal expression of NOS activity in the mucosa at a distance of 2 cm. Similarly, there was no significant difference between the control mucosa and the peritumoral mucosa obtained at a distance of 10 cm (P = 0.383). The expression of NOS activity in all tissues examined was abolished by preincubation of tissue with the selective NOS inhibitor L-NMMA but not with D-NMMA. Our data showed extensive and significant reduction as identified by the NAD(P)H diaphorase method in the expression of NOS activity, thereby reflecting the activity of nitric oxide in colon cancer and colonic polyps. The generalized suppression of this activity, which precedes the onset of overt neoplasia, may be an important event in colon carcinogenesis. This aberrant expression could also be compatible with the selective advantage to either tumor promotion and metastatic progression or to tumoricidal activity.
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PMID:Aberrant expression of nitric oxide synthase in human polyps, neoplastic colonic mucosa and surrounding peritumoral normal mucosa. 752 94

High consumption of fruits and vegetables which are abundant in dietary antioxidants has been linked to a reduced incidence of colorectal cancer. A potential mechanism of dietary anticarcinogenesis involves the induction of detoxifying phase II enzymes, including NAD(P)H:quinone reductase (QR) and glutathione-S-transferase (GST). This study therefore examined the ability of the dietary antioxidant vitamins beta-carotene, alpha-tocopherol and ascorbic acid to induce cellular expression of QR and GST activities in human colon cancer cells. Colo205 cells were cultured in the presence or absence of various concentrations (10(-10) to 10(-5) M) of each antioxidative micronutrient, then assessed for cytosolic QR and GST activities and cell growth. beta-Carotene, alpha-tocopherol and ascorbic acid each resulted in dose-dependent increases in QR activity, without adverse effects upon cell proliferation. To investigate whether the ability of beta-carotene to induce QR may be attributable to its conversion to vitamin A and/or to its antioxidant capacity as a carotenoid, retinol, retinoic acid, and lycopene were similarly tested for their capacity for enzyme induction. Although retinol and retinoic acid were both noted to be antiproliferative at higher concentrations (10(-6) to 10(-5) M), both retinoids stimulated QR at physiological concentrations. Lycopene, a carotenoid which is not converted to vitamin A, was devoid of biologic activity. By contrast with the effects upon QR, GST activity was unaffected by treatment with any of the micronutrients tested in this in vitro model. The results support a hypothesis that a high dietary consumption of vitamins A, E and C may confer partial protection against colorectal cancer by the induction of specific detoxifying enzymes. The antioxidant capacity of beta-carotene appears to have less biologic impact vis-a-vis QR induction than its function as a non-toxic reservoir of vitamin A. Measurements of QR activity within the colorectal mucosa may provide an index of cancer susceptibility, and may be an appropriate surrogate endpoint biomarker for colorectal cancer prevention studies involving diet modification or specific relevant micronutrients.
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PMID:Induction of NAD(P)H:quinone reductase by vitamins A, E and C in Colo205 colon cancer cells. 852 7

Poly(ADP-ribose)polymerase (PARP) has been implicated in DNA repair mechanisms and the associated activity shown to markedly increase after DNA damage in carcinogen-treated cells. A defective DNA repair has been associated to the aetiology of human cancers. In order to assess the potential role of this enzyme in cellular response to DNA damage by gamma-radiation, we studied the activity of PARP in patients with familial adenomatous polyposis (FAP). We compared poly(ADP-ribose)polymerase activity by the rate of incorporation of radioactivity from [3H]adenine-NAD+ into acid-insoluble material in permeabilized leucocytes from FAP patients and healthy volunteers. Concomitantly, the intracellular levels of NAD+--the substrate for the PARP--and the reduced counterpart NADH were determined using an enzymatic cycling assay 30 min after [60Co] gamma-ray cells irradiation. Our results demonstrate that a marked stimulation of PARP activity is produced upon radiation of the cells from healthy subjects but not in the FAP leucocytes, which concomitantly show a marked decrease in total NAD-/NADH content. Our observations point to a role of PARP in the repair of the gamma-radiation-induced DNA lesions through a mechanism that is impaired in the cells from FAP patients genetically predisposed to colon cancer. The differences observed in PARP activation by gamma-radiation in patients and healthy individuals could reflect the importance of PARP activity dependent on treatment with gamma-rays. The absence of this response in FAP patients would seem to suggest a possible defect in the role of PARP in radiation-induced DNA repair in this cancer-prone disease.
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PMID:Absence of stimulation of poly(ADP-ribose) polymerase activity in patients predisposed to colon cancer. 963 38

The present study used a rapid and single-step method for genotyping of NAD(P)H quinone oxidoreductase (NQO1) codon 609 polymorphism using real-time polymerase chain reaction (PCR)-analysis and subsequent melting curve analysis for the analysis of allelic distribution of NQO1. The design was a case control study of 323 Caucasians with colorectal cancer and 205 healthy controls. There was no difference in the frequencies of the mutated NQO1 allele (NQO1*2): 0.190 for control individuals and 0.195 for cancer patients, respectively (P=0.947). When this allelic distribution was further compared between non-smoking and smoking colorectal cancer patients, it appeared that the frequency of the wild-type allele NQO1*1 was higher in the smoking than in the non-smoking group [Odds ratio (OR), 0.434; 95% confidence interval (CI), 0.13-1.42]. This observation may suggest a protective role of the NQO1 wild-type allele in colon cancer susceptibility of individuals exposed to NQO1-inducing chemicals.
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PMID:NAD(P)H quinone oxidoreductase 1 codon 609 polymorphism and its association to colorectal cancer. 1066 83

Benzamide riboside, a recently discovered inhibitor of IMP dehydrogenase (IMPDH) exhibits oncolytic activity. IMPDH is the key enzyme of de novo guanylate biosynthesis and was shown to be linked with proliferation. Therefore, IMPDH is a very good target for antitumor therapy. In order to be active, benzamide riboside has to be converted to BAD, an NAD analogue that binds to the NAD site on IMPDH. Inhibition of the enzyme by benzamide riboside selectively inhibits tumor cell growth and induces apoptosis in various human tumor cell lines. In this manuscript we describe the induction of the CD71 transferrin receptor in human promyelocytic leukemia HL-60 cells following treatment with benzamide riboside. The results indicate a possible involvement of the iron metabolism in the action of this new compound. Benzamide riboside might be clinically used in the treatment of leukemia and solid tumors, alone or as part of combination therapy. Since transferrin receptors are overexpressed in certain cancers, such as glioma and colon cancer, a combination therapy that includes benzamide riboside in transferrin-coupled liposomes will not only target cancer cells but also leads to suicidal action because benzamide riboside will upregulate transferrin receptors on cancer cells thereby make it accessible to dose-intensive chemotherapy. We therefore believe that benzamide riboside itself or derivatives of benzamide riboside might become an important addition for the treatment to diseases that are otherwise fatal.
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PMID:Benzamide riboside, a recent inhibitor of inosine 5'-monophosphate dehydrogenase induces transferrin receptors in cancer cells. 1196 39

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

We recently showed that zerumbone, a sesquiterpene found in subtropical ginger, suppresses colonic tumor marker formation in rats and induces apoptosis in colon cancer cell lines. In our present study, the anti-tumor initiating and promoting activities of zerumbone in mouse skin were evaluated using a conventional 2-stage carcinogenesis model. A single topical pretreatment to mouse skin (2 micromol) 24 hr before application of dimethylbenz[a]anthracene (0.2 micromol) markedly suppressed tumor incidence by 60% and the number of tumors by 80% per mouse. Repeated pretreatment (16 nmol) twice weekly during the post-initiation phase reduced the number of 12-O-tetradecanoylphorbol-13-acetate (TPA, 1.6 nmol)-induced tumors by 83% as well as their diameter by 57%. Multiple reverse transcriptase (RT) PCR experiments revealed that zerumbone (2 micromol) enhanced the mRNA expression level of manganese superoxide dismutase, glutathione peroxidase-1, glutathione S-transferase-P1 and NAD(P)H quinone oxidoreductase in the epidermis, but not that of cytochrome p450 1A1 or 1B1. Further, it diminished TPA-induced cyclooxygenase-2 protein expression and phosphorylation of extracellular signal-regulated kinase 1/2, while pretreatment(s), in either the priming or activation stage or both, reduced double TPA application-induced hydrogen peroxide formation and edema induction by 29% to 86%, respectively. Histologic examination revealed that pretreatment(s) with zerumbone suppressed leukocyte infiltration and reduced proliferating cell nuclear antigen-labeling indices. Together, our results indicate that zerumbone is a promising agent for the prevention of both tumor initiating and promoting processes, through induction of anti-oxidative and phase II drug metabolizing enzymes as well as attenuation of proinflammatory signaling pathways.
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PMID:Zerumbone, a sesquiterpene in subtropical ginger, suppresses skin tumor initiation and promotion stages in ICR mice. 1512 79

RH1 (2,5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone), which is currently in clinical trials, is a diaziridinyl benzoquinone bioreductive anticancer drug that was designed to be activated by the obligate two-electron reductive enzyme NAD(P)H quinone oxidoreductase 1 (NQO1). In this electron paramagnetic resonance (EPR) study we showed that RH1 was reductively activated by the one-electron reductive enzyme NADPH cytochrome P450 reductase and by a suspension of HCT116 human colon cancer cells to yield a semiquinone free radical. As shown by EPR spin trapping experiments RH1 was reductively activated by cytochrome P450 reductase and underwent redox cycling to produce damaging hydroxyl radicals in reactions that were both H2O2- and iron-dependent. Thus, reductive activation by cytochrome P450 reductase or other reductases to produce a semiquinone that can redox cycle to produce damaging hydroxyl radicals and/or DNA-reactive alkylating species may contribute to the potent cell growth inhibitory effects of RH1. These results also suggest that selection of patients for treatment with RH1 based on their expression levels of NQO1 may be problematic.
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PMID:The reductive activation of the antitumor drug RH1 to its semiquinone free radical by NADPH cytochrome P450 reductase and by HCT116 human colon cancer cells. 1701 78

Human AIF-M2 is an unusual flavoprotein oxidoreductase that binds DNA, nicotinamide coenzyme, and the modified flavin 6-hydroxy-FAD. Using multiple solution methods to investigate the redox chemistry and binding interactions of AIF-M2, we demonstrate that binding of DNA and coenzyme to AIF-M2 is mutually exclusive. We also show that DNA binding does not perturb the redox chemistry of AIF-M2, but it has significant effects on the reduction kinetics of the 6-hydroxy-FAD cofactor by NAD(P)H. Based on quantitative analysis of ligand binding and redox chemistry, we propose a model for the function of AIF-M2. In this model, DNA binding suppresses the redox activity of AIF-M2 by preventing the binding of the reducing coenzyme NAD(P)H. This DNA-mediated suppression of AIF-M2 activity is expected to lower cellular levels of superoxide and peroxide, thereby lessening survival signaling by Ras, NF-kappaB, or AP-1, as suggested from knock-out studies of the related AIF in human colon cancer cell lines. We show marked differences between AIF-M2 and AIF. DNA and coenzyme binding activity is retained in the C-terminal deletion mutant AIF-M2-(Delta319-613), whereas DNA binds to the C-terminal D3 domain of AIF. Our work provides the first analysis of AIF-M2 ligand interactions and redox chemistry and identifies an important mechanistic connection between coenzyme and DNA binding, redox activity, and the apoptotic function of AIF-M2. Through its DNA binding activity, we suggest that AIF-M2 lessens survival cell signaling in the presence of foreign (e.g. bacterial and (retro)viral) cytosolic DNA, thus contributing to the onset of apoptosis.
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PMID:DNA binding suppresses human AIF-M2 activity and provides a connection between redox chemistry, reactive oxygen species, and apoptosis. 1771 48

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