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)

Apple procyanidins have chemopreventive properties in a model of colon cancer, they affect intracellular signalling pathways, and trigger apoptosis in a human adenocarcinoma-derived metastatic cell line (SW620). In the present study we investigated relationships between procyanidin-induced alterations in polyamine metabolism and apoptotic effects. Apple procyanidins diminish the activities of ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase, key enzymes of polyamine biosynthesis, and they induce spermidine/spermine N(1)-acetyltransferase, which initiates retroconversion of poly-amines. As a consequence of the enzymatic changes polyamine concentrations are diminished, and N(1)-acetyl-polyamines accumulate in SW620 cells. In contrast with expectations MDL 72527, an inactivator of polyamine oxidase (PAO), improved the anti-proliferative effect of procyanidins, and caused an increase of the proportion of apoptotic cells, although it prevented the formation of hydrogen peroxide and 3-acetamidopropanal, the cytotoxic products of PAO-catalysed degradation of N(1)-acetylspermidine and N1-acetylspermine. Addition of 500 microM N1-acetylspermidine to the culture medium in the presence of procyanidins mimicked the effect of MDL 72527. Therefore we presume that the enhanced procyanidin-triggered apoptosis by MDL 72527 is mediated by the accumulation of N(1)-acetyl-polyamines. The observation that apple procyanidins enhance polyamine catabolism and reduce polyamine biosynthesis activity similar to known inducers of SSAT, without sharing their toxicity, and the potentiation of these effects by low concentrations of MDL 72527 suggests apple procyanidins for chemopreventive and therapeutic interventions.
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PMID:Potentiation of apple procyanidin-triggered apoptosis by the polyamine oxidase inactivator MDL 72527 in human colon cancer-derived metastatic cells. 1682 Aug 85

The efficacy of dietary apigenin, a dietary flavonoid, in colon cancer prevention was investigated by evaluating the inhibition of the ornithine decarboxylase (ODC) activity and the formation of aberrant crypt foci (ACF) and by studying the ability of apigenin to block colon carcinogenesis in two mouse models. First, the activity of ODC was measured in colon cancer cells (Caco-2) and in the colon epithelium of CF-1 mice. Apigenin at 10 and 30 muM significantly inhibited the ODC activity of Caco-2 cells by 26% and 57%, respectively. Colonic ODC activity in CF-1 mice was reduced with 0.1% dietary apigenin by 42% compared with the control, but this difference was not statistically significant. Second, ACF formation was evaluated in azoxymethane (AOM)-induced CF-1 mice. Female CF-1 mice at 6 wk of age were i.p. injected with 5 mg/kg body weight (BW) AOM once to induce ACF. ACF formation in CF-1 mice was reduced by 50% (P < 0.05) with 0.1% dietary apigenin fed for 6 wk when compared with the control. Dietary apigenin inhibited ACF only in the distal region of the CF-1 mouse colon. Finally, tumorigenesis studies were conducted using two different mouse models: AOM-induced CF-1 mice and Min mice with mutant adenomatous polyposis coli (APC) gene. Female CF-1 mice at 6 wk of age were i.p. injected with 10 mg/kg BW AOM weekly for 6 (AOM Study I) or 4 (AOM Study II) wk to induce tumors. CF-1 mice were fed diets containing 0.025% or 0.1% apigenin for 23-25 wk. Female Min mice were fed diets for 10 wk beginning at 5 wk of age. In two AOM-treated mouse colon tumor studies 0.025% and 0.1% dietary apigenin modestly reduced tumors in the group fed 0.025% apigenin (25% incidence in comparison with 65% in the controls) in a non-dose response manner. Apigenin failed to inhibit adenoma formation in the Min mouse study. These results suggest that dietary apigenin showed promise in cancer prevention by reducing the ODC activity and ACF formation, however, clear evidence of cancer prevention was not obtained in mouse tumor studies. Further investigation of the potential chemopreventive effect of apigenin in carcinogenesis is warranted.
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PMID:Effect of dietary apigenin on colonic ornithine decarboxylase activity, aberrant crypt foci formation, and tumorigenesis in different experimental models. 1689 69

ODC (ornithine decarboxylase), a key enzyme of polyamine biosynthesis, is an inducible enzyme exhibiting high activity in tumour cells, suggesting ODC as a target for antineoplastic therapy. Among the inhibitors of polyamine-related enzymes, the ODC inactivator DFMO [2-(difluoromethyl)ornithine] became the most well-known. The drug is usually cytostatic and its effects on growth are reversed by micromolar concentrations of polyamines in the cellular environment. ODC inactivation is associated with decreased transcription of the growth-related c-myc and c-fos genes. DFMO used as a single drug has only minor effects on tumour growth. The low efficacy of the drug is due to the use of exogenous (gastrointestinal) polyamines by the mammalian organism. Although it was disappointing in most therapeutic attempts, DFMO showed potential in cancer chemoprevention based on its ability to lower polyamine levels in colorectal mucosa at low dosages with no demonstrable toxicity over long periods of use. DFMO in combination with other drugs prevents and inhibits the development of a variety of chemically induced cancers in animals with doses far lower than those administered for therapy. Low doses of several NSAIDs (non-steroidal anti-inflammatory drugs) and DFMO administered in combination have been shown to be more effective in inhibiting chemically induced colon tumours in rats than are high doses of these agents given individually. This combination has gained further interest after findings suggesting that ODC polymorphism is a genetic marker for colon cancer risk and supporting the use of DFMO and aspirin or other NSAIDs in combination as a strategy for colon cancer prevention.
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PMID:Revival of 2-(difluoromethyl)ornithine (DFMO), an inhibitor of polyamine biosynthesis, as a cancer chemopreventive agent. 1737 Dec 77

Polyamine metabolic genes are downstream targets of several genes commonly mutated in colon adenomas and cancers. Inhibitors of ornithine decarboxylase, such as difluoromethylornithine (DFMO), and agents that stimulate polyamine acetylation and export, such as non-steroidal anti-inflammatory drugs (NSAIDS), act at least additively to arrest growth in human cell models and suppress intestinal carcinogenesis in mice. These preclinical studies provided the rationale for colon cancer prevention trials in humans. A Phase IIb clinical study comparing the combination of DFMO and the NSAID sulindac versus placebo was conducted. Endpoints were colorectal tissue polyamine and prostaglandin E2 contents and overall toxicity to participants. Participants in the Phase IIb study served as a vanguard for a randomized, placebo-controlled prospective Phase III trial of the combination of DFMO and sulindac with the primary study endpoint the prevention of colon polyps. Seventy percent of participants will have completed the three years of treatment in December 2006.
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PMID:Rationale for, and design of, a clinical trial targeting polyamine metabolism for colon cancer chemoprevention. 1739 14

Chitosan oligosaccharide (COS, 3 kDa<MW<5 kDa) was tested for colon cancer chemoprevention by measuring the activities of quinine reductase (QR) and glutathione-S-transferase (GST), glutathione (GSH) levels, ornithine decarboxylase (ODC) activity, and cyclooxygenase (COX)-2 expression in HT-29 cells treated with COS. COS induced QR activity in a dose-dependent manner over a concentration range of 0.1-4.0 mg/ml. GST activity was also induced in HT-29 cells treated with COS. In addition, GSH levels were increased 1.3-, 1.4-, and 1.5-fold with COS at 2, 3, and 4 mg/ml, respectively. ODC activity induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) was inhibited by 33% and 39% with 3 and 4 mg/ml of COS, respectively. COS also inhibited the expression of TPA-induced COX-2 protein in HT-29 cells. These results suggest that COS has colon cancer chemopreventive activity by increasing QR and GST activities and GSH levels and by inhibiting ODC activity and COX-2 expression in vitro.
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PMID:Chemopreventive effect of chitosan oligosaccharide against colon carcinogenesis. 1806 35

We examined the effects of polysaccharides extracted from Asterina pectinifera on the activities of quinone reductase (QR), glutathione S-transferase (GST), ornithine decarboxylase (ODC), cyclooxygenase (COX)-2 and glutathione (GSH) levels in HT-29 human colon adenocarcinoma cells. We found that the polysaccharides extract induced QR activity in a dose-dependent manner over a concentration range of 20 approximately 60 microg/ml and increased GST activity as much as 1.4-fold over controls. GSH levels were increased 1.3- and 1.5-fold with the extract at 40 and 60 microg/ml, respectively. The activity and protein expression of ODC in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced colon cancer cells was inhibited by the extract. The polysaccharides suppressed TPA-induced prostaglandin (PG) production. These data indicate that polysaccharides from A. pectinifera increase phase II detoxification enzyme activity and inhibit ODC and COX-2 activities in HT-29 human colon adenocarcinoma cells. Consequently, this effect may contribute to the protective effect of polysaccharides from A. pectinifera against colon cancer.
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PMID:Chemopreventive effects of polysaccharides extract from Asterina pectinifera on HT-29 human colon adenocarcinoma cells. 1947 Feb 41

The nonsteroidal anti-inflammatory drug (NSAID) sulindac and the ornithine decarboxylase (ODC) antagonist difluoromethylornithine (DFMO), individually and together, are effective inhibitors of colon carcinogenesis. However, chronic use of sulindac is associated with significant side effects. We evaluated the chemopreventive efficacy of phospho-sulindac (P-S, OXT-328), an apparently safe derivative of sulindac, together with DFMO, in HT-29 human colon cancer xenografts. Nude mice were divided into four groups as follows: group 1 received vehicle (corn oil); group 2 received P-S (100 mg/kg/d) by oral gavage; group 3 received DFMO (2% in drinking water); and group 4 received P-S (100 mg/kg/d) by gavage plus DFMO (2% in drinking water; P-S/DFMO). Eighteen days after implantation, compared with controls, tumor volume was inhibited 65.9% by P-S, 52.9% by DFMO, and 70.9% by P-S/DFMO (P < 0.01 for all). P-S/DFMO reduced cell proliferation 27.1% and increased apoptosis 38.9% compared with controls (P < 0.05 for both). Compared with controls, P-S reduced the levels of thioredoxin-1 (Trx-1) and thioredoxin reductase (TrxR), whereas DFMO reduced polyamine content (putrescine and spermidine) and TrxR levels. Importantly, P-S/DFMO decreased putrescine and spermidine levels and the expression of Trx-1, TrxR, and cyclooxygenase (COX) 2. Of these molecular targets, TrxR most consistently correlated with tumor growth. Study results show that P-S/DFMO is an efficacious drug combination for colon cancer prevention and also show the safety of P-S, which may overcome the limiting side effects of conventional sulindac. P-S/DFMO has an intricate mechanism of action extending beyond polyamines and including the thioredoxin system, an emerging regulator of chemoprevention. P-S/DFMO merits further evaluation.
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PMID:Phospho-sulindac (OXT-328) combined with difluoromethylornithine prevents colon cancer in mice. 2146 38

The role of dietary factors in prevention of chemically-induced cancer was reviewed on two models: i) the role of high fiber diets in prevention of colon cancer and ii) the role of high fat diets in prevention of mammary gland cancer, i) Experiments in colon cancer showed that 20% cellulose content decreased tumor incidence caused by 1,2-dimethylhydrazine (DMH) to 33% compared with 92% of tumors developed in animals fed a fiber-free diet. The tumor-preventive effect of a cellulose diet was accompanied by increased enzyme concentrations, such as ornithine decarboxylase, thymidine kinase and beta-glucuronidase. Corncob fiber (15%), treated with the fungus Pleurotus os., had a significant protective effect against DMH-induced rat colon cancer. This effect was accompanied by activation of some cellular mechanisms, i.e. apoptosis, proliferating cell nuclear antigen (PCNA) and p53 protein synthesis. A high positive correlation was found between tumor grade and p53 protein in the serum (r=0.97) or in the cell cytoplasm (r=0.77), and between tumor grade and PCNA (r=0.81). An inverse relationship was found between tumor grade and apoptosis (r=-0.63). ii) Experiments in mammary gland cancer showed that a 15% olive-oil diet reduced tumor incidence caused by 9,10-dimethyl-1,2-benzanthracene to 30%, compared with 55% in the control group. The antitumor effect of the olive oil diet was connected to its content of monounsaturated fatty acids, such as oleic and palmitic acids. The promotive tumorigenic effects of other high-fat diets (avocado, soybeans) were associated with high content of some polyunsaturated fatty acids (linoleic and alpha-linolenic). We concluded that different diets have different targets. The effect of the same diet depends on its content of anti-tumor substances.
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PMID:The role of dietary factors in prevention of chemically-induced cancers (review). 2152 16

Previously, we reported (Carcinogenesis 15: 1317-1323, 1994) a high rate of activating point mutations in I ns proto-oncogenes in azoxymethane (AOM)-induced colon tumors, and a significant suppression of these mutations by dietary administration of chemopreventive agents, D,L-alpha-difluoromethylornithine (DFMO) and piroxicam. To understand the role of p53 tumor suppressor gene in chemoprevention of colon cancer and to study the association of p53 gene alterations with activation of ras genes, we determined point mutations in conserved regions (exons 5-9) of p53 gene and analyzed the occurrence of double event of ms activation acid p53 mutation. Groups of male F344 rats were fed the modified AIN-76A diet containing 0, 4000 ppm DFMO, or 150 ppm piroxicam and administered s.c. AOM at a dose rate of 15 mg/kg body wt, once weekly, for 4 weeks. Vehicle controls received s.c. equal volume of normal saline. Animals were sacrificed 32 weeks after the last AOM or saline injection and their grossly visible colon tumors were analyzed to determine p53 mutations by PCR amplification based single strand conformation polymorphism (SSCP) and direct DNA sequencing. Our results demonstrate that about 57% tumors from animals fed the control diet contained predominantly missense but also nonsense mutations, whereas only 30% tumors from animals on piroxicam diet, and none (0%) from animals fed the DFMO diet had similar mutations. Analysis of data revealed that about half of the tumors from animals on control diet possessed both ms and p53 mutations together, only 27% of colon tumors from animals on piroxicam diet and none of the tumors from animals on DFMO diet exhibited both ms and p53 mutations. These results indicate that the administration of piroxicam, a non-steroidal anti-inflammatory drug, and DFMO, a irreversible inhibitor of ornithine decarboxylase, may inhibit selective proliferation of initiated cells containing activated las and/or mutant p53. Dietary DFMO exerted more pronounced inhibition of selective amplification of initiated cells containing mutated ras and/or p53.
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PMID:Modulation of alterations in p53 tumor suppressor gene and its association with activation of ras proto-oncogenes during chemoprevention of colon cancer. 2153 96

Accumulating data suggest that activation of ms proto-oncogenes and inactivation of tumor suppressor genes induce malignant phenotype in colonic cells. However, the transforming ability of ras oncogenes critically depends on correct localization of ras-p21 in plasma membrane. In our previous studies, we demonstrated a strong correlation between the modulation of ras activation (both in terms of mutational activation and over-expression of ras genes) by chemopreventive agents and colon tumor outcome during different stages of azoxymethane (AOM)-induced colon carcinogenesis. In the present study, which is a part of our ongoing investigations on the role of ras in chemoprevention of colon cancer, we studied the effect of D,L-alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, and piroxicam, a non-steroidal antiinflammatory drug (NSAID), on the post-translational membrane association of ras-p21 during AOM-induced colon carcinogenesis. Groups of male F344 rats were fed the modified AIN-76A diets containing 0, 150 ppm piroxicam or 4000 ppm DFMO, and administered s.c. AOM dissolved in normal saline at a dose rate of 15 mg/kg body weight/week for 4 weeks. Vehicle control groups received equal volume of normal saline. Groups of animals were then sacrificed at 4, 16, 24, and 32 weeks after last AOM or saline injection and their colonic mucosa and tumors were analyzed for cytoplasmic as well as membrane bound ras-p21 levels. AOM-treatment resulted in increasingly higher levels of membrane-bound ras-p21 with advancing stages of colon tumorigenesis without any significant changes in cytoplasmic ras-p21. Dietary DFMO significantly suppressed AOM-induced membrane-bound ras-p21 in a time-dependent manner. Administration of piroxicam though resulted in significant inhibition of membrane-bound ras-p21, but concomitantly increased the cytosolic levels of ras-p21. Inhibition of membrane-bound ras-p21 levels by DFMO and piroxicam strongly correlated with the suppression of AOM-induced colon tumorigenesis by these agents. Data from the present and earlier studies suggest that DFMO may afford chemoprevention by suppressing DNA and protein biosynthesis by depleting intracellular polyamines, whereas piroxicam may exert its antitumor activity by interfering with post-translational membrane localization of ras-p21, in addition to modulating arachidonic acid metabolism.
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PMID:Effect of chemopreventive agents on posttranslational plasmamembrane association of ras-p21 during chemoprevention of azoxymethane-induced colon carcinogenesis. 2155 37

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