Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Colon tumors expressing high levels of beta-catenin and c-myc have been reported in male F344 rats given three short cycles of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) alternating with a high-fat (HF) diet. Using the same experimental protocol, rats were euthanized 24 h after the last dose of PhIP so as to examine early changes in colonic crypt homeostasis and beta-catenin expression, before the onset of frank tumors. PhIP/HF dosing caused a significant increase in the bromodeoxyuridine labeling index throughout the entire colon, and within the colonic crypt column cleaved caspase-3 was elevated in the basal and central zones, but reduced in the luminal region. In vehicle/HF controls, beta-catenin was immunolocalized primarily at the border between cells at the top of the crypt, whereas in rats given PhIP/HF diet there was strong cytoplasmic staining, which appeared as a gradient of increased beta-catenin extending from the base of the crypt column to the luminal region. Quantitative real-time PCR and immunoblot analyses confirmed that beta-catenin and c-myc were increased significantly in the colonic mucosa of rats given PhIP/HF diet. Collectively, these findings suggest that PhIP/HF cycling alters beta-catenin and c-myc expression in the colonic mucosa, resulting in expansion of the proliferative zone and redistribution of apoptotic cells from the lumen to the central and basal regions of the colonic crypt. Thus, during the early stages of colon carcinogenesis, alternating exposure to heterocyclic amines and a high-fat diet might facilitate molecular changes resulting in dysregulated beta-catenin and c-myc expression.
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PMID:beta-catenin is strongly elevated in rat colonic epithelium following short-term intermittent treatment with 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and a high-fat diet. 1861 82

Patients with inflammatory bowel diseases are at increased risk for colorectal cancer, but the molecular mechanisms linking inflammation and cancer are not well defined. We earlier showed that carboxylated N-glycans expressed on receptor for advanced glycation end products (RAGE) and other glycoproteins mediate colitis through activation of nuclear factor kappa B (NF-kappaB). Because NF-kappaB signaling plays a critical role in the molecular pathogenesis of colitis-associated cancer (CAC), we reasoned that carboxylated glycans, RAGE and its ligands might promote CAC. Carboxylated glycans are expressed on a subpopulation of RAGE on colon cancer cells and mediate S100A8/A9 binding to RAGE. Colon tumor cells express binding sites for S100A8/A9 and binding leads to activation of NF-kappaB and tumor cell proliferation. Binding, downstream signaling and tumor cell proliferation are blocked by mAbGB3.1, an anti-carboxylate glycan antibody, and by anti-RAGE. In human colon tumor tissues and in a mouse model of CAC, we found that myeloid progenitors expressing S100A8 and S100A9 infiltrate regions of dysplasia and adenoma. mAbGB3.1 administration markedly reduces chronic inflammation and tumorigenesis in the mouse model of CAC and RAGE-deficient mice are resistant to the onset of CAC. These findings show that RAGE, carboxylated glycans and S100A8/A9 play essential roles in tumor-stromal interactions, leading to inflammation-associated colon carcinogenesis.
Carcinogenesis 2008 Oct
PMID:RAGE, carboxylated glycans and S100A8/A9 play essential roles in colitis-associated carcinogenesis. 1868 72

The modifying effect of dietary exposure to a flavonoid, luteolin (LUT) during the azoxymethane (AOM)-induced colon carcinogenesis was investigated in this study. Aberrant crypt foci (ACF), lipid peroxidation (LPO), enzymic and non-enzymic antioxidants and histopathological analysis were performed. Colon carcinogenesis was induced by injecting 15 mg/body kg weight of AOM, intraperitoneally (i.p.), once in a week for 3 weeks in male Balb/c mice. AOM-induced mice were treated with LUT (1.2mg of LUT/kg body weight/day orally). After the experimental period, frequency of ACF, levels of thiobarbutaric acid reactive substances (TBARS) and hydroxy radical (OH ) were found to be increased, whereas glutathione (GSH), Vitamins C, E and A were decreased in the plasma and colon of AOM-induced mice. However, LUT treatment to AOM-induced mice significantly decreased the incidence of ACF, levels of TBARS and OH with a concordant increase in non-enzymic antioxidants in plasma and colon tissue. The activities of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were found to be decreased due to the induction of colon cancer in mouse. LUT treatment ameliorated the activities of these antioxidant enzymes. The histological study revealed a significant increase in the enlarged nuclei and hyperchromatism of cells in AOM-induced mice whereas LUT significantly reduced the signs in the colon. The immunohistochemical expression of MDA-DNA adduct was studied. In AOM-induced group, the expression was increased and treatment with LUT decreased significantly. The present study depicts that LUT can act as an effective chemopreventive agent against colon cancer.
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PMID:Protective role of luteolin on the status of lipid peroxidation and antioxidant defense against azoxymethane-induced experimental colon carcinogenesis. 1869 83

Dietary fibres are indigestible food ingredients that reach the colon and are then fermented by colonic bacteria, resulting mainly in the formation of short-chain fatty acids (SCFA) such as acetate, propionate, and butyrate. Those SCFA, especially butyrate, are recognised for their potential to act on secondary chemoprevention by slowing growth and activating apoptosis in colon cancer cells. Additionally, SCFA can also act on primary prevention by activation of different drug metabolising enzymes. This can reduce the burden of carcinogens and, therefore, decrease the number of mutations, reducing cancer risk. Activation of GSTs by butyrate has been studied on mRNA, protein, and enzyme activity level by real-time RT-PCR, cDNA microarrays, Western blotting, or photometrical approaches, respectively. Butyrate had differential effects in colon cells of different stages of cancer development. In HT29 tumour cells, e.g., mRNA GSTA4, GSTP1, GSTM2, and GSTT2 were induced. In LT97 adenoma cells, GSTM3, GSTT2, and MGST3 were induced, whereas GSTA2, GSTT2, and catalase (CAT) were elevated in primary colon cells. Colon cells of different stages of carcinogenesis differed in post-transcriptional regulatory mechanisms because butyrate increased protein levels of different GST isoforms and total GST enzyme activity in HT29 cells, whereas in LT97 cells, GST protein levels and activity were slightly reduced. Because butyrate increased histone acetylation and phosphorylation of ERK in HT29 cells, inhibition of histone deacetylases and the influence on MAPK signalling are possible mechanisms of GST activation by butyrate. Functional consequences of this activation include a reduction of DNA damage caused by carcinogens like hydrogen peroxide or 4-hydroxynonenal (HNE) in butyrate-treated colon cells. Treatment of colon cells with the supernatant from an in vitro fermentation of inulin increased GST activity and decreased HNE-induced DNA damage in HT29 cells. Additional animal and human studies are needed to define the exact role of dietary fibre and butyrate in inducing GST activity and reducing the risk of colon cancer.
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PMID:Mechanisms of primary cancer prevention by butyrate and other products formed during gut flora-mediated fermentation of dietary fibre. 1938 51

Inflammation has been shown to contribute to both tumor development and antitumor immunity. However, conditions determining these opposing effects are not well understood. Suppressor of cytokine signaling 1 (SOCS1) has been shown to play an important role in regulating inflammation and tumor development. It has been reported that silencing of SOCS1 gene in dendritic cells potentiates antitumor immunity, while SOCS1-deficiency in whole organs except for T and B cells enhances inflammation-mediated colon tumor development. To determine which types of cells are important for the suppression of tumor development by SOCS1-deficiency, we employed the conditional knockout strategy. SOCS1 gene was deleted in macrophages and neutrophils by crossing SOCS1-flox/flox mice with LysM-cre mice. Resulting conditional knockout (cKO) mice showed enhanced sensitivity to endotoxin shock. SOCS1-cKO mice survived much longer than wild-type mice after B16 melanoma transplantation. Colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH) plus dextran sulfate sodium (DSS) was also reduced in SOCS1-cKO mice. SOCS1-deficiency in monocytic cells enhanced tumor-killing activity of macrophages and tumor-specific cytotoxic T cell activity. These results suggest that inflammation induced by SOCS1-deficiency in monocytes potentiates antitumor immune responses rather than tumor-promoting inflammation.
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PMID:Silencing of SOCS1 in macrophages suppresses tumor development by enhancing antitumor inflammation. 1946 17

An elevated proteasome activity contributes to tumorigenesis, particularly by providing cancer cells with antiapoptotic protection and efficient clearance from irregular proteins. Still, the underlying mechanisms are poorly known. In this study, we report that in colon cancer patients, higher proteasome activity was detected in tumoral tissue compared with surrounding normal tissue, and also that increased levels of proteasomal subunit proteins, such as S5a/PSMD4 and alpha-5/PSMA5, could be detected. Colon tumors showed higher nuclear levels of nuclear factor E2-related factor 2 (Nrf2), a transcription factor supposed to be involved in the control of proteasomal subunit protein expression. The induction or overexpression of Nrf2 led to stronger S5a and alpha-5 expression in the human colon cancer cell lines, Colo320 and Lovo, as well as in NCM460 colonocytes along with higher proteasome activity. The small interfering RNA (siRNA)-mediated Nrf2 knockdown decreased S5a and alpha-5 expression and reduced proteasome activity. Additionally, Nrf2-dependent S5a and alpha-5 expression conferred protection from tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, an effect preceded by an increased nuclear factor (NF)-kappaB activation and higher expression of antiapoptotic NF-kappaB target genes. These findings point to an important role of Nrf2 in the gain of proteasome activity, thereby contributing to colorectal carcinogenesis. Nrf2 may therefore serve as a potential target in anticancer therapy.
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PMID:Increased proteasome subunit protein expression and proteasome activity in colon cancer relate to an enhanced activation of nuclear factor E2-related factor 2 (Nrf2). 1973 40

The present study evaluated the modulatory effects of zinc on colonic membrane fluidity and surface abnormalities following 1,2 dimethylhydrazine (DMH)-induced colon carcinogenesis. Rats were segregated into four groups: normal control, DMH treated, zinc treated, DMH + zinc treated. Colon carcinogenesis was initiated through weekly subcutaneous injections of DMH (30 mg/kg body weight) for 8 weeks. Zinc (in the form of zinc sulphate) was supplemented to rats at a dose level of 227 mg/L in drinking water, ad libitum, for the entire duration of the study. Brush border membranes (BBM) were isolated from the colon of rats and the fluidity parameters were assessed by steady-state fluorescence polarization technique using the membrane extrinsic fluorophore 1,6-diphenyl-1,3,5-hexatriene (DPH). The translational diffusion was measured by using the excimer formation of pyrene incorporated in the membrane. The results demonstrated a significant increase in the polarization and anisotropy, accompanied by an increase in order parameter in the membrane preparations from the colon of DMH-injected rats. Further, studies with pyrene fluorophore indicated a marked decrease in membrane microviscosity following DMH treatment. However, the alterations in membrane fluorescence polarization and the fluidity parameters were completely restored following zinc treatment. Drastic alterations in colon surface were noticed after 8 weeks of DMH treatment. However, zinc treatment to DMH-treated rats greatly restored normalcy in the colonic surface. The study concludes that zinc has a strong membrane stabilizing effect and thus has a positive beneficial effect against chemically induced colonic preneoplastic progression in rats.
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PMID:Membrane fluidity and surface changes during initiation of 1,2 dimethylhydrazine-induced colon carcinogenesis: protection by zinc. 1991

Colorectal cancer is a major cause of morbidity and mortality in industrialized societies and leads to significant treatment costs. Currently there are screening programs with fecal occult blood testing, radiographic, and endoscopic evaluation. Despite this, mortality from colorectal cancer has not improved dramatically. As such, attention has turned to finding agents to prevent carcinogenesis. The emerging field known as chemoprevention studies agents that target multiple steps in the development of adenomas and their subsequent transformation to colorectal carcinoma. There are multiple case control, cohort, and randomized controlled trials investigating the efficacy of fiber, calcium, vitamin D, folate, and nonsteroidal antiinflammatory drugs as chemopreventive agents against colorectal cancer.
Clin Colon Rectal Surg 2008 Nov
PMID:Chemoprevention for colorectal neoplasia. 2001 43

Stilbenes are phytochemicals present in grapes, berries, peanuts and red wine. A widely studied stilbene, resveratrol (trans-3,5,4'-trihydroxystilbene), has been shown to exert antioxidant, anti-inflammatory, chemopreventive and antiaging effects in a number of biological systems. We reported earlier that pterostilbene (trans-3,5-dimethoxy-4'-hydroxystilbene), a structurally related stilbene found in blueberries, was effective in reducing the incidence and multiplicity of aberrant crypt foci formation in the colon of rats injected with azoxymethane (AOM). Our present study was to identify the chemopreventive potential of pterostilbene with colonic tumor formation as an end point and further to evaluate the mechanistic action of pterostilbene during colon carcinogenesis. F344 rats were given two AOM injections subcutaneously when they were 7 and 8 weeks old and continuously fed the control or 40 p.p.m. pterostilbene diet for 45 weeks. Overall analyses indicated that pterostilbene reduced colon tumor multiplicity of non-invasive adenocarcinomas, lowered proliferating cell nuclear antigen and downregulated the expression of beta-catenin and cyclin D1. Pterostilbene decreased mucosal levels of the proinflammatory cytokines, tumor necrosis factor-alpha, interleukin (IL)-1beta and IL-4. Colon tumors from pterostilbene-fed animals showed reduced expression of inflammatory markers as well as nuclear staining for phospho-p65, a key molecule in the nuclear factor-kappaB pathway. In HT-29 cells, pterostilbene reduced the protein levels of beta-catenin, cyclin D1 and c-MYC, altered the cellular localization of beta-catenin and inhibited the phosphorylation of p65. Our data with pterostilbene in suppressing colon tumorigenesis, cell proliferation as well as key inflammatory markers in vivo and in vitro suggest the potential use of pterostilbene for colon cancer prevention.
Carcinogenesis 2010 Jul
PMID:Dietary intake of pterostilbene, a constituent of blueberries, inhibits the beta-catenin/p65 downstream signaling pathway and colon carcinogenesis in rats. 2006 62

The present study evaluated the chemopreventive potential of mate tea-like intake on mammary and colon carcinogenesis initiated by 7,12-dimethylbenz(a)antracene (DMBA) and 1,2-dimethylhydrazine (DMH) in female Swiss mice. After the initiation period, the animals received basal diet and organic mate tea-like, conventional mate tea-like, or green tea (positive control) at 2.0% as the drinking fluid during 15 weeks. At week 20, colon and mammary gland were analyzed for preneoplastic and neoplastic lesions development. Colon and mammary gland complexes were processed for cell proliferation analysis, estimated by proliferating cell nuclear antigen labeling index (PCNA-LI%). Specially, organic mate tea-like reduced the values of PCNA-LI% in colonic crypts (p < .003) and in mammary glands (p < .05) in DMBA/DMH-initiated groups. A lower incidence of aberrant crypt foci (ACF) in colon (p = .03) and of hyperplastic and neoplastic lesions in mammary gland (p < .05 and p < .02, respectively) was observed in DMBA/DMH-initiated groups treated with organic mate tea-like. These results suggest that post-initiation treatment with organic mate tea-like inhibited the development of colon and mammary carcinogenesis in a two-step medium-term mouse carcinogenesis model.
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PMID:Chemopreventive effects of mate against mouse mammary and colon carcinogenesis. 2007 74


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