Selenium (Se) is known to prevent several cancers while the relationship between high iron and the risk of colorectal cancer is controversial. To investigate the effects of Se in colon carcinogenesis, we subjected three different levels of Se and high-iron diet to a mouse model of colon cancer in which animals were treated with three azoxymethane (AOM) injections followed by dextran sodium sulfate (DSS) administration. There were five experimental groups including vehicle group [normal-Fe (NFe, 45 ppm)+medium-Se (MSe, 0.1 ppm)], positive control group (AOM/DSS+NFe+MSe), AOM/DSS+high-Fe (HFe, 450 ppm)+low-Se (LSe, 0.02 ppm), AOM/DSS+HFe+MSe, and AOM/DSS+HFe+high-Se (HSe, 0.5 ppm). The animals were fed on the three different Se diets for 24 weeks. The incidence of colon tumor in the high-Se diet group (AOM/DSS+HFe+HSe) showed 19.4% lower than positive control group, 5.9% lower than AOM/DSS+HFe+MSe diet group, and 11.1% lower than AOM/DSS+HFe+LSe group. The tumor multiplicity was significantly higher in the low-Se diet group (AOM/DSS+HFe+LSe) compare to all other AOM/DSS treated groups. In the high-Se diet group, the activity of hepatic GPx was comparable to that of positive control group, and significantly higher than those of low-Se or medium-Se diet groups. Expression level of hepatic GPx-1 showed similar results. Hepatic malondialdehyde (MDA) level (indicator of oxidative stress) in the low-Se diet group showed the highest compared to the other groups, and it was significantly higher than positive control group. In the high-Se diet group the level of MDA in the liver was significantly lower than all other AOM/DSS treated groups. High-Se diet group showed significantly lower proliferative index than low-Se and medium-Se groups. The apoptotic indices in low-Se group and medium-Se group were significantly lower than positive control group. However, apoptotic index of high-Se diet group was significantly higher than all other AOM/DSS treated groups. These findings suggest that dietary Se supplement may have protective effect against colon cancer by decreasing proliferation, increasing apoptosis of tumor cells, and reducing oxidative stress in mice with high iron diet.
Animals ; Apoptosis ; Azoxymethane ; Colon ; Colonic Neoplasms ; Colorectal Neoplasms ; Dextrans ; Diet ; Incidence ; Iron ; Liver ; Malondialdehyde ; Mice ; Oxidative Stress ; Selenium ; Sodium ; Sulfates

BACKGROUND/AIMS: Early tumor detection is crucial for the prevention of colon cancer. Near-infrared fluorescence (NIRF) imaging using a target-activatable probe may permit earlier disease detection. Matrix metalloproteinases (MMPs) participate in tumorigenesis and tumor growth. The aim of this study was to determine whether NIRF imaging using an MMP-activatable probe can detect colon tumors at early stages. METHODS: We utilized two murine colon cancer models: a sporadic colon cancer model induced by azoxymethane (AOM), and a colitis-associated cancer model induced by a combination of AOM and dextran sodium sulfate (DSS). Colonic lesions were analyzed by histologic examination, Western blotting, immunohistochemical staining, and NIRF imaging using an MMP-activatable probe. RESULTS: Multiple variable-sized tumors developed in both models and progressed from adenomas to adenocarcinomas over time. At the early stage of the AOM/DSS model, diffuse inflammation was observed within the tumors. MMP expression increased progressively through normal, inflammation, adenoma, and adenocarcionoma stages. NIRF signal intensities were strongly correlated with each tumor stage from adenoma to adenocarcinoma. NIRF imaging also distinguished tumors from inflamed mucosa. CONCLUSIONS: NIRF imaging using a protease-activatable probe may be a useful tool for early tumor detection. This approach could translate to improve the endoscopic detection of colon tumors, especially in patients with inflammatory bowel disease.
Adenocarcinoma ; Adenoma ; Azoxymethane ; Blotting, Western ; Cell Transformation, Neoplastic ; Colon ; Colonic Neoplasms ; Dextrans ; Fluorescence ; Humans ; Inflammation ; Inflammatory Bowel Diseases ; Matrix Metalloproteinases ; Optical Imaging ; Sodium ; Sulfates

Colorectal cancer (CRC) is one of the leading causes of cancer death in western countries or in the developed countries. Zinc intake has been associated with decreased risk of CRC. We investigated the effect of zinc on the formation of colonic aberrant crypt foci (ACF) induced by azoxymethane followed by dextran sodium sulfate in mice. Five-week old ICR mice were fed with the different zinc levels (0.01, 0.1, 1 ppm) for 12 weeks. The numbers of ACF were measured in the colonic mucosa. The ACF number of HZn group was significantly low compared with LZn group or MZn group. Cytosolic superoxide dismutase activity was the highest in HZn group, while thiobarbituric acid reactive substance level for lipid peroxidation was the highest in LZn group. There was no difference in number of PCNA-positive proliferative cells among the groups. TUNEL-positive apoptotic cells were increased in HZn group compared with LZn group. The HZn group exhibited a decrease of beta-catenin immunostaining areas compared with the LZn or MZn group. These findings indicate that dietary zinc might exert a protecting effect against colon carcinogenesis by inhibiting the development of ACF in the mice.
Aberrant Crypt Foci ; Animals ; Azoxymethane ; beta Catenin ; Colon ; Colorectal Neoplasms ; Cytosol ; Developed Countries ; Dextrans ; Lipid Peroxidation ; Mice ; Mice, Inbred ICR ; Mucous Membrane ; Sodium ; Sulfates ; Superoxide Dismutase ; Thiobarbiturates ; Zinc

The possibility for cyclooxygenase (COX) inhibitors in colorectal cancer prevention and theraphy is evident from epidemiologic data (reduction of colorectal cancer in nonsteroidal anti-inflammatory drugs (NSAIDs) users), animal experiments (nude mouse xenograft tumor reduced by NSAIDs or reduction of colorectal cancer in APCmin mouse and azoxymethane treated rat by using NSAIDs), and molecular genetics. Among two variant COX, inducible COX-2 enzyme is more involved in tumorigenesis than constitutive COX-1 enzyme and molecular method have given us insight into the mechanism of colorectal cancer development by COX-2 such as, apoptosis, angiogenesis, invasiveness, and immune modulation. Based on that COX-2 is involved in tumor promotion during colorectal cancer progress, a large number of prevention and treatment trials of colorectal cancer have been started. And many trials to elucidate the function of prostaglandin produced by COX-2 are now in progress.
Animal Experimentation ; Animals ; Anti-Inflammatory Agents, Non-Steroidal ; Apoptosis ; Azoxymethane ; Carcinogenesis ; Colorectal Neoplasms* ; Cyclooxygenase 2 ; Heterografts ; Mice ; Molecular Biology ; Prostaglandin-Endoperoxide Synthases ; Rats

Indole-3-carbinol (I3C) found in various cruciferous vegetables has been shown to exert anti-carcinogenic activity in several target organs. Our study was conducted to assess the modifying effect of I3C on the development of colon tumor induced by azoxymethane (AOM). Eighty-seven male F344 rats were divided into 5 groups and were treated with AOM followed by I3C 100 or 300 ppm, AOM alone, I3C alone, and non-treatment, respectively. The animals were subcutaneously injected with AOM. Then diet containing I3C were fed to the rats for 37 weeks. All rats were sacrificed at 40 weeks. Liver and kidney weights of rats treated with I3C at doses of 100 or 300 ppm were significantly increased compared to those of the control group. Colonic tumor incidence and multiplicity of rats treated with I3C at doses of 100 and 300 ppm were not significant compared to those of AOM alone group. In the pathological examination, most of tumors were classified with adenoma and adenocarcinoma in the small and large intestine. These results demonstrated that I3C may have not chemopreventive effect on the rat colon carcinogenesis.
Adenocarcinoma ; Adenoma ; Animals ; Azoxymethane ; Colon ; Diet ; Humans ; Incidence ; Indoles ; Intestine, Large ; Kidney ; Liver ; Male ; Rats ; Rats, Inbred F344 ; Vegetables ; Weights and Measures

Animals ; Apoptosis ; Azoxymethane ; Colorectal Neoplasms ; chemically induced ; metabolism ; pathology ; Cytoskeletal Proteins ; metabolism ; Precancerous Conditions ; chemically induced ; metabolism ; pathology ; Rats ; Rats, Inbred F344 ; Trans-Activators ; metabolism ; beta Catenin

Since azoxymethane (AOM)-dextran sodium sulfate (DSS) induced tumorigenesis was used to explore inflammation-associated carcinogenesis of sporadic colorectal cancer (CRC), different administration modes of AOM or DSS have been reported. In this article we optimized the protocol of the AOM-DSS modeling using C57BL/6 mice for study on sporadic CRC by intraperitoneal injecting AOM solution at a proper concentration with a 100 μl sterile syringe once, feeding with DSS solution for 7 days in a roll and change DSS solution every day. More than 100 C57BL/6 mice had been treated with the optimized protocol, and all mice were demonstrated suffering from colorectal tumors when sacrificed in 8 to 20 weeks after AOM injection. These tumors mainly occurred in distal segment of colorectum with an increase in tumor density, which was similar to CRC in human beings. Tumor per mouse was high, and variation of tumor number per mouse was low. The histology of tumor developed through the defined stage ranged from precursor lesions, adenomatous lesions, adenomas to adenocarcinomas. The modified protocol of AOM-DSS model is easy, cheap, with high tumor formation rate of colorectal tumors.
Adenocarcinoma/pathology* ; Adenoma/pathology* ; Animals ; Azoxymethane ; Body Weight ; Carcinogenesis/pathology* ; Colorectal Neoplasms/pathology* ; Dextran Sulfate ; Disease Models, Animal ; Male ; Mice, Inbred C57BL

BACKGROUND/AIMS: The aim of this study was to investigate the protective effect of açaí against azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colorectal cancer development. METHODS: The effect of açaí on tumorigenesis was assessed by evaluating tumor incidence, multiplicity and invasiveness in the mouse colon. The levels of myeloperoxidase (MPO) and proinflammatory cytokines (tumor necrosis factor α [TNF-α], interleukin [IL]-1β, and IL-6) were measured via enzyme-linked immunosorbent assay. Protein levels of cyclooxygenase 2 (COX-2), proliferating cell nuclear antigen (PCNA), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated death promoter (Bad) and cleaved-caspase-3 were assessed by immunoblotting. RESULTS: Administration of pellets containing 5% açaí powder reduced the incidences of both colonic adenoma and cancer (adenoma, 23.1% vs 76.9%, respectively, p=0.006; cancer, 15.4% vs 76.9%, respectively, p=0.002). In the açaí-treated mice, the MPO, TNF-α, IL-1β and IL-6 levels in the colon were significantly down-regulated. Açaí inhibited PCNA and Bcl-2 expression and increased Bad and cleaved-caspase-3 expression. In vitro studies demonstrated that açaí treatment reduced lipopolysaccharide-induced expression of TNF-α, IL-1β, IL-6 and COX-2 in murine macrophage RAW 264.7 cells. CONCLUSIONS: Açaí demonstrated protective effects against AOM/DSS-induced colon carcinogenesis, which suggests that the intake of açaí may be beneficial for the prevention of human colon cancer.
Adenoma ; Animals ; Azoxymethane ; Carcinogenesis* ; Colon* ; Colonic Neoplasms ; Colorectal Neoplasms ; Cyclooxygenase 2 ; Cytokines ; Enzyme-Linked Immunosorbent Assay ; Fruit* ; Humans ; Immunoblotting ; In Vitro Techniques ; Incidence ; Interleukin-6 ; Interleukins ; Lymphoma, B-Cell ; Macrophages ; Mice* ; Necrosis ; Peroxidase ; Proliferating Cell Nuclear Antigen ; RAW 264.7 Cells ; Sodium

The role of selenium (Se) in modulating colon carcinogenesis induced by azoxymethane (AOM) followed by dextran sodium sulfate (DSS) was investigated in mice. Five-week old ICR mice were fed on diets containing different concentrations (0.02, 0.1 or 0.5 ppm) of Se for 24 weeks. Animals received three (0-2nd weeks) intraperitoneal injections of AOM (10 mg/kg body weight), followed by 2% DSS with drinking water for additional 1 week. There were 4 experimental groups including vehicle control group, positive control group given AOM/DSS with AIN-93G normal diet containing 0.1% Se (NSe), a low (0.02 ppm)-Se diet group (LSe) and a high (0.5 ppm)-Se diet group (HSe). Hematology was analyzed with a blood cell differential counter. Liver Se was analyzed by inductively coupled plasma-mass spectroscopy. Cell proliferation and apoptosis were determined by using proliferating cell nuclear antigen (PCNA) for proliferative activity and apoptotic index by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), respectively. HSe group showed a low incidence of colonic tumor (64.7%), compared with the NSe positive control (75%) and LSe (77.8%) groups. In contrast, HSe group exhibited lower rate of PCNA-positive cells (39.3+/-6.9%) than positive control (64.3+/-0.3%) and LSe (57.3+/-2.9%) groups. In addition, apoptotic index of HSe group was higher than those of positive control and LSe groups. These results indicate that Se is a chemopreventive agent for colon carcinogenesis induced by AOM+DSS in male ICR mice.
Animals ; Apoptosis ; Azoxymethane ; Blood Cells ; Cell Proliferation ; Colon ; Colonic Neoplasms ; Dextrans ; Diet ; Drinking Water ; Hematology ; Humans ; Incidence ; Injections, Intraperitoneal ; Liver ; Male ; Mice ; Mice, Inbred ICR ; Organothiophosphorus Compounds ; Proliferating Cell Nuclear Antigen ; Selenium ; Sodium ; Spectrum Analysis ; Sulfates

The role of selenium (Se) in modulating colon carcinogenesis induced by azoxymethane (AOM) followed by dextran sodium sulfate (DSS) was investigated in mice. Five-week old ICR mice were fed on diets containing different concentrations (0.02, 0.1 or 0.5 ppm) of Se for 24 weeks. Animals received three (0-2nd weeks) intraperitoneal injections of AOM (10 mg/kg body weight), followed by 2% DSS with drinking water for additional 1 week. There were 4 experimental groups including vehicle control group, positive control group given AOM/DSS with AIN-93G normal diet containing 0.1% Se (NSe), a low (0.02 ppm)-Se diet group (LSe) and a high (0.5 ppm)-Se diet group (HSe). Hematology was analyzed with a blood cell differential counter. Liver Se was analyzed by inductively coupled plasma-mass spectroscopy. Cell proliferation and apoptosis were determined by using proliferating cell nuclear antigen (PCNA) for proliferative activity and apoptotic index by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), respectively. HSe group showed a low incidence of colonic tumor (64.7%), compared with the NSe positive control (75%) and LSe (77.8%) groups. In contrast, HSe group exhibited lower rate of PCNA-positive cells (39.3+/-6.9%) than positive control (64.3+/-0.3%) and LSe (57.3+/-2.9%) groups. In addition, apoptotic index of HSe group was higher than those of positive control and LSe groups. These results indicate that Se is a chemopreventive agent for colon carcinogenesis induced by AOM+DSS in male ICR mice.
Animals ; Apoptosis ; Azoxymethane ; Blood Cells ; Cell Proliferation ; Colon ; Colonic Neoplasms ; Dextrans ; Diet ; Drinking Water ; Hematology ; Humans ; Incidence ; Injections, Intraperitoneal ; Liver ; Male ; Mice ; Mice, Inbred ICR ; Organothiophosphorus Compounds ; Proliferating Cell Nuclear Antigen ; Selenium ; Sodium ; Spectrum Analysis ; Sulfates