8-hydroxy-2--deoxyguanosine and Colonic-Neoplasms

Inflammation, high fat, high red meat and low fiber consumption have for long been known as the most important etiological factors of sporadic colorectal cancers (CRC). Colon cancer originates from neoplastic transformation in a single layer of epithelial cells occupying colonic crypts, in which migration and apoptosis program becomes disrupted. This results in the formation of polyps and metastatic cancers. Mutational program in sporadic cancers involves APC gene, in which mutations occur most abundantly in the early phase of the process. This is followed by mutations in RAS, TP53, and other genes. Progression of carcinogenic process in the colon is accompanied by augmentation of the oxidative stress, which manifests in the increased level of oxidatively damaged DNA both in the colon epithelium, and in blood leukocytes and urine, already at the earliest stages of disease development. Defence mechanisms are deregulated in CRC patients: (i) antioxidative vitamins level in blood plasma declines with the development of disease; (ii) mRNA level of base excision repair enzymes in blood leukocytes of CRC patients is significantly increased; however, excision rate is regulated separately, being increased for 8-oxoGua, while decreased for lipid peroxidation derived ethenoadducts, ɛAde and ɛCyt; (iii) excision rate of ɛAde and ɛCyt in colon tumors is significantly increased in comparison to asymptomatic colon margin, and ethenoadducts level is decreased. This review highlights mechanisms underlying such deregulation, which is the driving force to colon carcinogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Cell Transformation, Neoplastic; Colonic Neoplasms; DNA Adducts; DNA Damage; DNA Repair; Guanine; Humans; Oxidative Stress

Aims of this study were to test whether sleep fragmentation (SF) increased carcinogenesis and to investigate the possible mechanisms of carcinogenesis in a chemical-induced colon cancer model. In this study, eight-week-old C57BL/6 mice were divided into Home cage (HC) and SF groups. After the azoxymethane (AOM) injection, the mice in the SF group were subjected to SF for 77 days. SF was accomplished in a sleep fragmentation chamber. In the second protocol, mice were divided into 2% dextran sodium sulfate (DSS)-treated, HC, and SF groups and were exposed to the HC or SF procedures. Immunohistochemical and immunofluorescent stainings were conducted to determine the level of 8-OHdG and reactive oxygen species (ROS), respectively. Quantitative real-time polymerase chain reaction was used to assess the relative expression of inflammatory and ROS-generating genes. The number of tumors and average tumor size were significantly higher in the SF group than in the HC group. The intensity (%) of the 8-OHdG stained area was significantly higher in the SF group than in the HC group. The fluorescence intensity of ROS was significantly higher in the SF group than the HC group. SF accelerated cancer development in a murine AOM/DSS-induced model of colon cancer, and the increased carcinogenesis was associated with ROS- and oxidative stress-induced DNA damage.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Azoxymethane; Carcinogenesis; Colitis; Colon; Colonic Neoplasms; Dextran Sulfate; Disease Models, Animal; Mice; Mice, Inbred C57BL; Reactive Oxygen Species; Sleep Deprivation

An inverse association between serum lycopene levels and the risk of cancers has been pointed out by many prospective and retrospective epidemiological studies which prompted more studies to be performed on animal models and cell cultures in order to test this hypothesis. The aim of the present study was to evaluate the antiproliferative and pro-apoptotic effect of lycopene on colon cancer HT-29 cell line. The effect of lycopene on the viability of HT-29 cell line was investigated using XTT assay. The levels of Bcl-2, cleaved caspase 3, BAX, cleaved PARP, and 8-oxo-dG in lycopene-treated HT-29 cells were measured using ELISA. Gamma-H2AX and cytochrome c expression was assessed semi-quantitatively using immunofluorescence staining. Lycopene at doses of 10 and 20 μM produced a significant antiproliferative effect on HT-29 cells compared to the control (p < 0.05). The IC

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Cell Proliferation; Colonic Neoplasms; HT29 Cells; Humans; Lycopene; Poly(ADP-ribose) Polymerase Inhibitors; Prospective Studies; Retrospective Studies

Colorectal cancer is the third most lethal and fourth most commonly diagnosed cancer worldwide. Sinapic acid, a derivative of hydroxycinnamic acid, is a promising phytochemical exhibiting numerous pharmacological activities in various systems. It is a substantial chain-breaking antioxidant that operates as a radical scavenger. The aim of this research was to investigate the antiproliferative effect of sinapic acid on the HT-29 cell line besides the mechanisms underlying this activity. The effect of sinapic acid on the viability of HT-29 cell line was investigated using XTT assay. The levels of BCL-2, cleaved caspase 3, BAX, cleaved PARP, and 8-oxo-dG were measured using ELISA. Gamma-H2AX and cytochrome

Topics: 8-Hydroxy-2'-Deoxyguanosine; Apoptosis; bcl-2-Associated X Protein; Caspase 3; Cell Proliferation; Colonic Neoplasms; Coumaric Acids; Cytochromes c; HT29 Cells; Humans; Poly(ADP-ribose) Polymerase Inhibitors

The active DNA demethylation mechanism involves 5-methylcytosine (5-mCyt) enzymatic oxidation with the subsequent formation of 5-hydroxymethylcytosine (5-hmCyt), which can be further oxidized to 5-formylcytosine (5-fCyt) and 5-carboxylcytosine (5-caCyt). The products of active DNA demethylation are released into the bloodstream and eventually also appear in urine. We used online two-dimensional ultraperformance liquid chromatography with tandem mass spectrometry (2D-UPLC-MS/MS) to compare DNA methylation marks and 8-oxo-2'-deoxyguanosine (8-oxodG) in colorectal cancer and pre-cancerous condition in urine. The study included four groups of subjects: healthy controls, patients with inflammatory bowel disease (IBD), persons with adenomatous polyps (AD), and individuals with colorectal cancer (CRC). We have found that the level of 5-fCyt in urine was significantly lower for CRC and polyp groups than in the control group. The level of 5-hmCyt was significantly higher only in the CRC group compared to the control (2.3 vs. 2.1 nmol/mmol creatinine). Interestingly, we have found highly statistically significant correlation of 5-hydroxymethyluracil with 5-hydroxymethylcytosine, 5-(hydroxymethyl)-2'-deoxycytidine, 5-(hydroxymethyl)-2'-deoxyuridine, and 5-methyl-2'-deoxycytidine in the CRC patients' group.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Biomarkers; Chromatography, Liquid; Colonic Neoplasms; DNA; Epigenesis, Genetic; Humans; Tandem Mass Spectrometry

Active demethylation of 5-methyl-2'-deoxycytidine (5-mdC) in DNA occurs by oxidation to 5-(hydroxymethyl)-2'-deoxycytidine (5-hmdC) and further oxidation to 5-formyl-2'-deoxycytidine (5-fdC) and 5-carboxy-2'-deoxycytidine (5-cadC), and is carried out by enzymes of the ten-eleven translocation family (TETs 1, 2, 3). Decreased level of epigenetic DNA modifications in cancer tissue may be a consequence of reduced activity/expression of TET proteins. To determine the role of epigenetic DNA modifications in colon cancer development, we analyzed their levels in normal colon and various colonic pathologies. Moreover, we determined the expressions of TETs at mRNA and protein level.The study included material from patients with inflammatory bowel disease (IBD), benign polyps (AD), and colorectal cancer (CRC). The levels of epigenetic DNA modifications and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in examined tissues were determined by means of isotope-dilution automated online two-dimensional ultraperformance liquid chromatography with tandem mass spectrometry (2D-UPLC-MS/MS). The expressions of. IBD was characterized by the highest level of 8-oxodG among all analyzed tissues, as well as by a decrease in 5-hmdC and 5-mdC levels (at a midrange between normal colon and CRC). AD had the lowest levels of 5-hmdC and 5-mdC of all examined tissues and showed an increase in 8-oxodG and 5-(hydroxymethyl)-2'-deoxyuridine (5-hmdU) levels. CRC was characterized by lower levels of 5-hmdC and 5-mdC, the lowest level of 5-fdC among all analyzed tissues, and relatively high content of 5-cadC. The expression of. Our findings suggest that a complex relationship between aberrant pattern of DNA epigenetic modification and cancer development does not depend solely on the transcriptional status of TET proteins, but also on the characteristics of premalignant/malignant cells. This study showed for the first time that the examined colonic pathologies had their unique epigenetic marks, distinguishing them from each other, as well as from normal colonic tissue. A decrease in 5-fdC level may be a characteristic feature of largely undifferentiated cancer cells.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Colonic Neoplasms; Colonic Polyps; Cytidine Deaminase; Deoxycytidine; Deoxyguanosine; Dioxygenases; DNA Methylation; DNA-Binding Proteins; Down-Regulation; Epigenesis, Genetic; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Inflammatory Bowel Diseases; Middle Aged; Mixed Function Oxygenases; Proto-Oncogene Proteins; Tissue Array Analysis

Zinc Oxide (ZnO) nanoparticles are widely used both in the industry and in biomedical applications for their chemical and physical nanomaterial properties. It is therefore essential to go in depth into the cytotoxicity mechanisms and interactions between nanomaterials and cells. The aim of this work was to evaluate the dissolution of ZnO nanoparticles and their uptake, from a few minutes after treatments up to 24h. ZnO nanoparticles routes of entry into the human colon carcinoma cells (LoVo) were followed at different times by a thorough ultrastructural investigation and semiquantitative analysis. The intracellular release of Zn(2+) ions by Zinquin fluorescent dye, and phosphorylated histone H2AX (γ-H2AX) expression were evaluated. The genotoxic potential of ZnO nanoparticles was also investigated by determining the levels of 8-hydroxyl-2'-deoxyguanosine (8-oxodG). The experimental data show that ZnO nanoparticles entered LoVo cells by either passive diffusion or endocytosis or both, depending on the agglomeration state of the nanomaterial. ZnO nanoparticles coming into contact with acid pH of lysosomes altered organelles structure, resulting in the release of Zn(2+) ions. The simultaneous presence of ZnO nanoparticles and Zn(2+) ions in the LoVo cells determined the formation of reactive oxygen species at the mitochondrial and nuclear level, inducing severe DNA damage.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Cell Line, Tumor; Colonic Neoplasms; Deoxyguanosine; Diffusion; DNA Damage; Endocytosis; Histones; Humans; Metal Nanoparticles; Mutagens; Reactive Oxygen Species; Zinc Oxide

The aim of this study was to evaluate if grape juice concentrate is able to protect against experimental colon carcinogenesis.. For this purpose, a total of 35 male Wistar rats were randomly distributed into seven groups: G1: SHAM animals receiving only saline; G2: animals receiving 15 mg/kg azoxymethane (AOM); G3: animals receiving 1% grape juice concentrate 2 weeks before the administration of AOM; G4: animals receiving 2% grape juice concentrate 2 weeks before the administration of AOM; G5: animals receiving 1% grape juice concentrate 4 weeks after the last administration of AOM; G6: animals receiving 2% grape juice concentrate 4 weeks after the last administration of AOM; G7: animals receiving only 2% grape juice concentrate.. The group that received 2% grape juice concentrate before induction with AOM showed the decreased expression of Bcl-2 compared to those animals that were induced by AOM (positive control). Regarding Bax, animals that received grape juice at 2% decreased Bax immunoexpression when compared to AOM group. Furthermore, animals that intake grape juice at 1% after induced by AOM decreased Bax immunoexpression as well. 8-OHdGLI did not show significant statistically differences (p > 0.05) among groups.. In summary, our results demonstrate that grape juice is able to modulate rat colon carcinogenesis as a result of induction of apoptosis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Anticarcinogenic Agents; Apoptosis; Azoxymethane; bcl-2-Associated X Protein; Cell Transformation, Neoplastic; Colon; Colonic Neoplasms; Deoxyguanosine; Disease Models, Animal; Fruit; Fruit and Vegetable Juices; Male; Oxidative Stress; Phytotherapy; Plants, Medicinal; Proto-Oncogene Proteins c-bcl-2; Rats, Wistar; Time Factors; Vitis

Geranylgeranylacetone (GGA), an isoprenoid compound, is an anti-ulcer drug developed in Japan. GGA protects a variety of cells and tissues against numerous stresses via induction of heat shock protein (HSP) 70, and it has recently been reported to protect mice from experimental ulcerative colitis (UC). However, it is unknown whether GGA exhibits a preventive effect on UC-associated neoplasia. In the present study, we evaluated the preventive effects of GGA on colitis-related carcinogenesis in the mouse colon. Mice were administered 1,2-dimethylhydrazine (DMH) subcutaneously three times within a week, followed by 2 cycles of dextran sulfate sodium (DSS) (each cycle, 3% DSS for 7 days and then distilled water for 14 days) and they were sacrificed 28 days after the completion of the 2 cycles. The mice were divided into the following groups according to the diet received during the experiment: group A, which received a standard diet and served as a disease control; group B, which received a diet mixed with 0.25% GGA; group C, which received a diet mixed with 0.5% GGA; group D, which received a diet mixed with 1.0% GGA; group E, which received a diet mixed with 2.0% GGA; and group F, which received a diet containing no agents, including DSS and served as a normal control. The incidence of neoplasia was assessed. The expression of inducible nitric oxide synthase (iNOS) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) was also determined. In addition, the expression of HSP70 in the colon tissues was determined by immunohistochemistry and western blot analysis. The mean number of tumors was 16.6, 11.0, 9.4, 5.8, 5.4 and 0 in groups A-F, respectively. GGA significantly suppressed the occurrence of neoplasia in a dose-dependent manner. GGA treatment enhanced the expression of HSP70 and suppressed the oxidative damage in the background mucosa (i.e. lesion-free colon). These results suggest that GGA could be useful in the prevention of UC-associated neoplasia.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antineoplastic Agents; Blotting, Western; Colitis, Ulcerative; Colonic Neoplasms; Deoxyguanosine; Diterpenes; Female; HSP70 Heat-Shock Proteins; Immunohistochemistry; Mice; Mice, Inbred BALB C; Nitric Oxide Synthase Type II; Reverse Transcriptase Polymerase Chain Reaction

In this work we investigated the genotoxicity of zinc oxide and titanium dioxide nanoparticles (ZnO NPs; TiO2 NPs) induced by oxidative stress on human colon carcinoma cells (Caco-2 cells). We measured free radical production in acellular conditions by Electron Paramagnetic Resonance technique and genotoxicity by micronucleus and Comet assays. Oxidative DNA damage was assessed by modified Comet assay and by measuring 8-oxodG steady state levels. The repair kinetics of DNA oxidation as well as the expression levels of hOGG1 were also analyzed. Even if both NPs were able to produce ROS in acellular conditions and to increase 8-oxodG levels in Caco-2 cells, only ZnO NPs resulted genotoxic inducing micronuclei and DNA damage. Furthermore, Caco-2 cells exposed to ZnO NPs were not able to repair the oxidative DNA damage that was efficiently repaired after TiO2 NPs treatment, through OGG1 involvement. These results indicate that the high oxidant environment caused by ZnO NPs in our cellular model can induce DNA damage and affect the repair pathways.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Caco-2 Cells; Colonic Neoplasms; Comet Assay; Deoxyguanosine; DNA Damage; DNA Glycosylases; Humans; Micronucleus Tests; Mutagens; Nanoparticles; Reactive Oxygen Species; Titanium; Zinc Oxide

The aim of this work was to answer the question whether the broad range of parameters which describe oxidative stress and oxidatively damaged DNA and repair are appropriate prognosis factors of colon cancer (CRC) patients survival? The following parameters were analyzed for 89 CRC patients: concentration of uric acid and vitamins A, E, C in plasma; levels of 8-oxodGuo (8-oxo-7,8-dihydro-2'-deoxyguanosine) in DNA of leukocyte and colon tissues; urinary excretion rates of 8-oxodGuo and 8-oxoGua (8-oxo-7,8-dihydroguanine); the activity and mRNA or protein level of repair enzymes OGG1, APE1, ANPG, TDG and PARP1. All DNA modifications and plasma antioxidants were analyzed using high performance liquid chromatography (HPLC) or HPLC/gas chromatography-mass spectrometry techniques. Expression of repair proteins was analyzed by QPCR, Western or immunohistochemistry methods. Longer survival coincided with low levels of 8-oxodGuo/8oxoGua in urine and 8-oxodGuo in DNA as well as with high concentration of uric acid plasma level. In contrast to expectations, longer survival coincided with lower mRNA level in normal colon tissue of the main 8-oxoGua DNA glycosylase, OGG1, but no association was found for PARP-1 expression. When analyzing simultaneously two parameters the discriminating power increased significantly. Combination of low level of urinary 8-oxoGua together with low level of 8-oxodGuo in leukocyte (both below median value) or high concentration of plasma uric acid (above median value) have the best prediction power. Since prediction value of these parameters seems to be comparable to conventional staging procedure, they could possibly be used as markers to predict clinical success in CRC treatment.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Case-Control Studies; Chromatography, High Pressure Liquid; Colonic Neoplasms; Deoxyguanosine; DNA Damage; DNA Repair Enzymes; Female; Follow-Up Studies; Gas Chromatography-Mass Spectrometry; Guanine; Humans; Male; Middle Aged; Neoplasm Staging; Oxidative Stress; Prognosis; Survival Rate; Uric Acid

Selenium (Se) is an essential micronutrient that exerts its functions via selenoproteins. Little is known about the role of Se in inflammatory bowel disease (IBD). Epidemiological studies have inversely correlated nutritional Se status with IBD severity and colon cancer risk. Moreover, molecular studies have revealed that Se deficiency activates WNT signaling, a pathway essential to intestinal stem cell programs and pivotal to injury recovery processes in IBD that is also activated in inflammatory neoplastic transformation. In order to better understand the role of Se in epithelial injury and tumorigenesis resulting from inflammatory stimuli, we examined colonic phenotypes in Se-deficient or -sufficient mice in response to dextran sodium sulfate (DSS)-induced colitis, and azoxymethane (AOM) followed by cyclical administration of DSS, respectively. In response to DSS alone, Se-deficient mice demonstrated increased morbidity, weight loss, stool scores, and colonic injury with a concomitant increase in DNA damage and increases in inflammation-related cytokines. As there was an increase in DNA damage as well as expression of several EGF and TGF-β pathway genes in response to inflammatory injury, we sought to determine if tumorigenesis was altered in the setting of inflammatory carcinogenesis. Se-deficient mice subjected to AOM/DSS treatment to model colitis-associated cancer (CAC) had increased tumor number, though not size, as well as increased incidence of high grade dysplasia. This increase in tumor initiation was likely due to a general increase in colonic DNA damage, as increased 8-OHdG staining was seen in Se-deficient tumors and adjacent, non-tumor mucosa. Taken together, our results indicate that Se deficiency worsens experimental colitis and promotes tumor development and progression in inflammatory carcinogenesis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Azoxymethane; Carcinogenesis; Colitis; Colonic Neoplasms; Deoxyguanosine; Dextran Sulfate; Diet; DNA Damage; Epidermal Growth Factor; Gene Expression Regulation; Inflammation; Mice; Mice, Inbred C57BL; Selenium; Signal Transduction; Transforming Growth Factor beta; Weight Loss

Obesity-related metabolic abnormalities, including chronic inflammation and oxidative stress, increase the risk of colorectal cancer. Dysregulation of the renin-angiotensin system (RAS) also plays a critical role in obesity-related metabolic disorders and in several types of carcinogenesis. In the present study, we examined the effects of an angiotensin-converting enzyme (ACE) inhibitor and angiotensin-II type 1 receptor blocker (ARB), both of which inhibit the RAS, on the development of azoxymethane (AOM)-initiated colonic premalignant lesions in C57BL/KsJ-db/db (db/db) obese mice. Male db/db mice were given 4 weekly subcutaneous injections of AOM (15 mg/kg body weight), and then, they received drinking water containing captopril (ACE inhibitor, 5mg/kg/day) or telmisartan (ARB, 5mg/kg/day) for 7 weeks. At sacrifice, administration of either captopril or telmisartan significantly reduced the total number of colonic premalignant lesions, i.e., aberrant crypt foci and β-catenin accumulated crypts, compared to that observed in the control group. The expression levels of TNF-α mRNA in the colonic mucosa of AOM-treated db/db mice were decreased by captopril and telmisartan. Captopril lowered the expression levels of TNF-α, IL-1β, IL-6, and PAI-1 mRNAs, while telmisartan lowered the expression levels of COX-2, IL-1β, IL-6, and PAI-1 mRNAs in the white adipose tissues of these mice. In addition, these agents significantly reduced the levels of urinary 8-OHdG, a surrogate marker of oxidative damage to DNA, in the experimental mice. These findings suggested that both ACE inhibitor and ARB suppress chemically-induced colon carcinogenesis by attenuating chronic inflammation and reducing oxidative stress in obese mice. Therefore, targeting dysregulation of the RAS might be an effective strategy for chemoprevention of colorectal carcinogenesis in obese individuals.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Angiotensin Receptor Antagonists; Angiotensin-Converting Enzyme Inhibitors; Animals; Azoxymethane; Benzimidazoles; Benzoates; Captopril; Colonic Neoplasms; Cyclooxygenase 2; Deoxyguanosine; Interleukin-1beta; Interleukin-6; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Obesity; Oxidative Stress; Plasminogen Activator Inhibitor 1; Precancerous Conditions; Renin-Angiotensin System; RNA, Messenger; Telmisartan; Tumor Necrosis Factor-alpha

Reactive oxygen species-induced oxidative stress in the colon is involved in inflammatory bowel diseases and suggested to be associated with colorectal cancer risk. However, our insight in molecular responses to different oxygen radicals is still fragmentary. Therefore, we studied global gene expression by an extensive time series (0.08, 0.25, 0.5, 1, 2, 4, 8, 16, or 24 h) analyses in human colon cancer (caco-2) cells after exposure to H(2)O(2) or the superoxide anion donor menadione. Differences in gene expression were investigated by hybridization on two-color microarrays against nonexposed time-matched control cells. Next to gene expression, correlations with related phenotypic markers (8-oxodG levels and cell cycle arrest) were investigated. Gene expression analysis resulted in 1404 differentially expressed genes upon H(2)O(2) challenge and 979 genes after menadione treatment. Further analysis of gene expression data revealed how these oxidant responses can be discriminated. Time-dependent coregulated genes immediately showed a pulse-like response to H(2)O(2), while the menadione-induced expression is not restored over 24 h. Pathway analyses demonstrated that H(2)O(2) immediately influences pathways involved in the immune function, while menadione constantly regulated cell cycle-related pathways Altogether, this study offers a novel and detailed insight in the similarities and differences of the time-dependent oxidative stress responses induced by the oxidants H(2)O(2) and menadione and show that these can be discriminated regarding their modulation of particular colon carcinogenesis-related mechanisms.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Antineoplastic Agents; Apoptosis; Caco-2 Cells; Cell Cycle; Colonic Neoplasms; Deoxyguanosine; Electron Spin Resonance Spectroscopy; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Hydrogen Peroxide; Microarray Analysis; Oxidants; Oxidative Stress; Reactive Oxygen Species; Vitamin K 3

Oxidative stress is involved in the pathogenesis of colon cancer. We wanted to elucidate at which stage of the disease this phenomenon occurs. In the examined groups of patients with colorectal cancer (CRC, n = 89), benign adenoma (AD, n = 77) and healthy volunteers (controls, n = 99), we measured: vitamins A, C and E in blood plasma, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanine (8-oxoGua) in leukocytes and urine, leukocyte 8-oxoGua excision activity, mRNA levels of APE1, OGG1, 8-oxo-7,8-dihydrodeoxyguanosine 5'-triphosphate pyrophosphohydrolase (MTH1) and OGG1 polymorphism. The vitamin levels decreased gradually in AD and CRC patients. 8-OxodG increased in leukocytes and urine of CRC and AD patients. 8-OxoGua was higher only in the urine of CRC patients. 8-OxoGua excision was higher in CRC patients than in controls, in spite of higher frequency of the OGG1 Cys326Cys genotype, encoding a glycosylase with decreased activity. mRNA levels of OGG1 and APE1 increased in CRC and AD patients, which could explain increased 8-oxoGua excision rate in CRC patients. MTH1 mRNA was also higher in CRC patients. The results suggest that oxidative stress occurs in CRC and AD individuals. This is accompanied by increased transcription of DNA repair genes, and increased 8-oxoGua excision rate in CRC patients, which is, however, insufficient to counteract the increased DNA damage.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenoma; Adenomatous Polyps; Adult; Aged; Aging; Antioxidants; Carcinoma; Case-Control Studies; Colonic Neoplasms; Deoxyguanosine; DNA Glycosylases; DNA Repair; DNA Repair Enzymes; DNA-(Apurinic or Apyrimidinic Site) Lyase; DNA, Neoplasm; Female; Gene Expression Regulation, Neoplastic; Humans; Male; Middle Aged; Neoplasm Staging; Oxidative Stress; Phosphoric Monoester Hydrolases; Polymorphism, Single Nucleotide; RNA, Messenger; Sex Characteristics; Smoking

The apoptotic effects of docosahexaenoic acid (DHA) and other omega-3 polyunsaturated fatty acids (PUFAs) have been documented in cell and animal studies. The molecular mechanism by which DHA induces apoptosis is unclear. Although there is no direct evidence, some studies have suggested that DNA damage generated through lipid peroxidation may be involved. Our previous studies showed that DHA, because it has a high degree of unsaturation, can give rise to the acrolein-derived 1,N(2)-propanodeoxyguanosine (Acr-dG) as a major class of DNA adducts via lipid oxidation. As a first step to investigate the possible role of oxidative DNA damage in apoptosis induced by DHA, we examined the relationships between oxidative DNA damage and apoptosis caused by DHA in human colon cancer HT-29 cells. Apoptosis and oxidative DNA damage, including Acr-dG and 8-oxo-deoxyguanosine (8-oxo-dG) formation, in cells treated with DHA and omega-6 PUFAs, including arachidonic acid (AA) and linoleic acid (LA), were measured. DHA induced apoptosis in a dose- and time-dependent manner with a concentration range from 0 to 300 microM as indicated by increased caspase-3 activity and PARP cleavage. In contrast, AA and LA had little or no effect at these concentrations. The Acr-dG levels were increased in HT-29 cells treated with DHA at 240 and 300 microM, and the increases were correlated with the induction of apoptosis at these concentrations, while no significant changes were observed for 8-oxo-dG. Because proteins may compete with DNA to react with acrolein, we then examined the effects of BSA on DHA-induced apoptosis and oxidative DNA damage. The addition of BSA to HT-29 cell culture media significantly decreases Acr-dG levels with a concomitant decrease in the apoptosis induced by DHA. The reduced Acr-dG formation is attributed to the reaction of BSA with acrolein as indicated by increased levels of total protein carbonyls. Similar correlations between Acr-dG formation and apoptosis were observed in HT-29 cells directly incubated with 0-200 microM acrolein. Additionally, DHA treatment increased the level of DNA strand breaks and caused cell cycle arrested at G1 phase. Taken together, these results demonstrate the parallel relationships between Acr-dG level and apoptosis in HT-29 cells, suggesting that the formation of Acr-dG in cellular DNA may contribute to apoptosis induced by DHA.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acrolein; Anticarcinogenic Agents; Apoptosis; Caspase 3; Cell Line, Tumor; Collagen Type XI; Colonic Neoplasms; Deoxyguanosine; DNA Adducts; DNA Damage; Docosahexaenoic Acids; Fatty Acids, Unsaturated; G1 Phase; HT29 Cells; Humans; Lipid Peroxidation

Genetic instability is a hallmark of human cancers. It is the driving force for tumor development as it facilitates the accumulation of mutations in genes that regulate cell death and proliferation and therefore promotes malignant transformation. Chronic inflammation is a common underlying condition for human tumor development, accounting for approximately 20% of human cancers. TNFalpha is an important inflammation cytokine and is crucial to the development of inflammation-associated cancers. We have shown that TNFalpha can cause DNA damages through reactive oxygen species (ROS). TNFalpha treatment in cultured cells resulted in increased gene mutations, gene amplification, micronuclei formation and chromosomal instability. Antioxidants significantly reduced TNFalpha-induced genetic damage. In addition, TNFalpha treatment alone led to increased malignant transformation of mouse embryo fibroblasts, which could be partially suppressed by antioxidants. Therefore, genetic instability plays an important role in inflammation-associated cancers.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Cell Transformation, Neoplastic; Cells, Cultured; Chromosomal Instability; Chromosome Aberrations; Chronic Disease; Colonic Neoplasms; Deoxyguanosine; Embryo, Mammalian; Fibroblasts; Humans; In Situ Hybridization, Fluorescence; Inflammation; Mice; Mice, Inbred BALB C; Mice, Nude; Micronucleus Tests; Reactive Oxygen Species; Tumor Necrosis Factor-alpha

8-Hydroxy-guanine (8-OH-G) mismatches readily with adenine residues, leading to a G : C to T : A transversion mutation. The human mutY homologue (MUTYH) excises adenine misincorporated opposite 8-OH-G during replication and suppresses mutations caused by reactive oxygen species. We defined the expression of 8-hydroxydeoxyguanosine (8-OHdG) and MUTYH in ulcerative colitis (UC)-associated neoplasia by immunohistochemistry and compared this with expression in UC patients without neoplasia and patients unaffected by UC. We also performed mutation analyses for MUTYH and K-ras. 8-OHdG was expressed more intensely in the mucosa of UC-associated neoplasia and UC without neoplasm than in the mucosa unaffected by UC. Immunohistochemistry with two different types of MUTYH antibody showed that UC-associated neoplasia and UC without neoplasia exhibited strong cytoplasmic expression and attenuated nuclear expression of MUTYH when compared with patients unaffected by UC. No pathological MUTYH mutations were detected in any of the UC-associated neoplasia cases. However, K-ras mutation was detected in two cases, one of which showed G : C to T : A transversion mutation and attenuated nuclear staining of MUTYH. In conclusion, inflamed mucosa of UC is exposed to oxidative damage. An increase in cytoplasmic MUTYH, rather than its mutation, may contribute to the promotion of carcinogenesis in UC.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Aged, 80 and over; Cell Nucleus; Colitis, Ulcerative; Colon; Colonic Neoplasms; Cytoplasm; Deoxyguanosine; DNA Glycosylases; DNA Mutational Analysis; Female; Gene Expression Regulation, Neoplastic; Genes, ras; Humans; Immunohistochemistry; Intestinal Mucosa; Male; Middle Aged; Mutation; Statistics, Nonparametric; Young Adult

The inhibitory effects of a novel prodrug, 3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoyl-L-alanyl-L-proline (GAP), of the secondary metabolite 4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoic acid (4'-geranyloxy-ferulic acid), on colon carcinogenesis was investigated using an azoxymetahen (AOM)/dextran sodium sulfate (DSS) model. GAP was synthetically derived from ferulic acid. Male CD-1 (ICR) mice initiated with a single intraperitoneal injection of azoxymethane (10 mg/kg body weight) were promoted by 1% (wt/vol) DSS in drinking water for 7 days. They were then given modified AIN-76A diet containing 0.01% or 0.05% GAP for 17 wk. At Week 20, the development of colonic adenocarcinoma was significantly inhibited by GAP feeding at dose levels of 0.01% [60% incidence (P = 0.0158) with a multiplicity of and 1.13 +/- 1.13 (P < 0.05)] and 0.05% [53% incidence (P = 0.0057) with a multiplicity of 0.08 +/- 1.08 (P < 0.01)], when compared to the AOM/DSS group (95% incidence with a multiplicity of 3.10 +/- 3.06). Dietary GAP modulated the mitotic and apoptotic indexes in the crypt cells and lowered 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive cells in the colonic mucosa. Urinary level of 8-OHdG was lowered by GAP feeding. Additionally, dietary GAP elevated the immunoreactivity of an inducible form of heme oxygenase 1 in the colonic mucosa. Our results indicate that GAP is able to inhibit colitis-related colon carcinogenesis by modulating proliferation and oxidative stress in mice.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Animals; Anticarcinogenic Agents; Azoxymethane; Carcinogens; Chemoprevention; Colitis; Colonic Neoplasms; Coumaric Acids; Deoxyguanosine; Dextran Sulfate; Dipeptides; Disease Models, Animal; Heme Oxygenase (Decyclizing); Intestinal Mucosa; Male; Mice; Mice, Inbred ICR; Oxidative Stress; Prodrugs

It has been known for a long time that DNA hypomethylation occurs in many human cancers and precancerous conditions. However, the mechanisms of hypomethylation are largely unknown. It is possible that endogenous 8-oxo-7,8-dihydroguanine (8-oxoGua) level may be linked to aberrant DNA methylation of adjacent cytosine and in this way influences carcinogenesis. Therefore, the aim of the present study was to assess a possible link between 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) background level and 5-methylcytosine content in DNA from human leukocytes of healthy subjects (n=105) as well as in patients with colon adenomas (n=39) and carcinomas (n=50). Our results demonstrated statistically significant negative correlation between background level of 8-oxodG and 5-methylcytosine content in DNA isolated from leukocytes of healthy donors (r=-0.3436, p=0.0003). The mean content of 5-methylcytosine was significantly lower, while 8-oxodG level was significantly higher in leukocytes DNA of patients with colon adenomas and carcinomas in comparison with healthy subjects. The mean values for 5-methylcytosine were: 3.59+/-0.173% (healthy subjects), 3.38+/-0.128% (patients with adenomas), 3.40+/-0.208% (colon cancer patients). The mean values of 8-oxodG in DNA were, respectively: 4.67+/-1.276, 5.72+/-1.787, 5.76+/-1.884 8-oxodG per 10(6) dG molecules. DNA from affected tissue (colon) suffered from significant, about 10% reduction in cytosine methylation in comparison with leukocytes of the paired subjects. Our work provides the first in vivo evidence suggesting that increased levels of 8-oxodG in DNA may lead to carcinogenesis not only via mispair/mutagenic potential of the modified base but also through its ability to influence gene expression by affecting DNA methylation.

Topics: 5-Methylcytosine; 8-Hydroxy-2'-Deoxyguanosine; Adenoma; Adult; Aged; Aged, 80 and over; Carcinoma; Colonic Neoplasms; Cytosine; Deoxyguanosine; DNA Damage; Female; Humans; Leukocytes; Male; Middle Aged

Oxidant/antioxidant balance has been suggested as an important factor for initiation and progression of cancer. In order to determine whether the degree of oxidative DNA damage and antioxidant enzyme activities in plasma obtained from patients with gastric and colon cancer who undergo resection can be used as a useful prognostic predictor, plasma level of 8-hydroxydeoxyguanosine (8-OHdG), activities of glutathione peroxidase (G-Px) and superoxide dismutase (SOD) were examined. 19 patients with gastric cancer and 26 patients with colon cancer who were undergoing resection of tumor were included by the study. Venous blood samples were taken just before the surgery. Plasma level of 8-OHdG was determined with ELISA, SOD and G-Px activities in plasma were measured by spectrophotometric kits. 8-OHdG level and activity of G-Px were found to be decreased, SOD activity was found to be increased in both gastric and colon cancer groups as compared to control group. Alpha fetoprotein was found to be correlated with G-Px in the gastric cancer group and correlated with 8-OHdG in the colon cancer group. SOD activity was correlated with CA-15-3 in the gastric cancer group. Low plasma level of 8-OHdG and altered antioxidant activity may implicate the deficient repair of oxidative DNA damage in patients with gastric and colon cancer. Those measured parameters were not found to be related with histopathological data but correlated with some tumor markers.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Aged; alpha-Fetoproteins; Antioxidants; Carcinoma, Adenosquamous; Carcinoma, Signet Ring Cell; Case-Control Studies; Colonic Neoplasms; Deoxyguanosine; DNA Damage; Enzyme-Linked Immunosorbent Assay; Female; Glutathione Peroxidase; Humans; Lymphoma, B-Cell; Male; Middle Aged; Oxidation-Reduction; Prognosis; Stomach Neoplasms; Superoxide Dismutase

The effects of esculetin (6,7-dihydroxycoumarin) and its 6-glycoside, esculin, on 8-oxo-2'-deoxyguanosine (8-oxodG) formation and carcinogenesis induced by a chemical carcinogen, 1,2-dimethylhydrazine (DMH), were examined in the colons of male Fischer 344 rats. Animals were given water containing esculetin or esculin for 7 d before subcutaneous injection of DMH (20 mg/kg body wt), killed 24 h after DMH treatment, and the levels of thiobarbituric acid reactive substances (TBARS) and 8-oxodG in the colons were determined. Both esculetin and esculin suppressed significantly the DMH-induced increases in 8-oxodG and TBARS in rat colon mucosa. We further investigated the modifying effect of esculin intake on the development of DMH-induced colonic aberrant crypt foci (ACF). Animals were given DMH once a week for 4 weeks to induce ACF. They then received water containing esculin ad libitum for 5 weeks (initiation phase) or 11 weeks after DMH treatment (post-initiation phase). Animals in the positive control group received tap water throughout the experiment. At the end of the experiment (16 weeks), the ingestion of esculin during the initiation phase significantly reduced the incidence of gross tumors, the number of ACF per rat and the mean number of AC per focus, while the esculin treatment during the post-initiation phase significantly decreased only the number of ACF per rat. These results suggest that esculin intake has an inhibitory effect on DMH-induced oxidative DNA damage and carcinogenesis in rat colons.

Topics: 1,2-Dimethylhydrazine; 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Carcinogens; Colonic Neoplasms; Deoxyguanosine; DNA Damage; Esculin; Intestinal Mucosa; Male; Oxidation-Reduction; Random Allocation; Rats; Rats, Inbred F344; Thiobarbituric Acid Reactive Substances; Umbelliferones

The aim of the present study was to investigate the chemoprotective activity of anthocyanin-rich extracts (AREs) from bilberry (Vaccinium myrtillus L.), chokeberry (Aronia meloncarpa E.), and grape (Vitis vinifera) by assessing multiple biomarkers of colon cancer in male rats treated with a colon carcinogen, azoxymethane. Fischer 344 male rats were fed the AIN-93 diet (control) or AIN-93 diet supplemented with AREs for 14 wk. Biomarkers that were evaluated included the number and multiplicity of colonic aberrant crypt foci (ACF), colonic cell proliferation, urinary levels of oxidative DNA damage, and expression of cyclooxygenase (COX) genes. To assess the bioavailability, levels of anthocyanins in serum, urine, and feces were evaluated. Total ACF were reduced (P<0.05) in bilberry, chokeberry, and grape diet groups compared with the control group. The number of large ACF was also reduced (P<0.05) in bilberry and chokeberry ARE-fed rats. Colonic cellular proliferation was decreased in rats fed bilberry ARE and chokeberry ARE diets. Rats fed bilberry and grape ARE diets had lower COX-2 mRNA expression of gene. High levels of fecal anthocyanins and increased fecal mass and fecal moisture occurred in ARE-fed rats. There was also a significant reduction (P<0.05) in fecal bile acids in ARE-fed rats. The levels of urinary 8-hydroxyguanosine were similar among rats fed different diets. These results support our previous in vitro studies suggesting a protective role of AREs in colon carcinogenesis and indicate multiple mechanisms of action.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Anthocyanins; Bile Acids and Salts; Biological Availability; Biomarkers; Body Weight; Cell Division; Colon; Colonic Neoplasms; Cyclooxygenase 2; Eating; Feces; Fruit; Guanine; Male; Phytotherapy; Plant Extracts; Rats; Rats, Inbred F344; RNA, Messenger; Rosaceae; Specific Pathogen-Free Organisms; Vaccinium myrtillus; Vitis; Water

Until recently it has been generally considered that genotoxic carcinogens have no threshold in exerting their potential for cancer induction. However, the nonthreshold theory can be challenged with regard to assessment of cancer risk to humans. In the present study we show that a food derived, genotoxic hepatocarcinogen, 2-amino-1-methyl-6-phenolimidazo[4,5-b]pyridine (PhIP), does not induce aberrant crypt foci (ACF) as preneoplastic lesions at low dose (below 50 ppm) or 8-hydroxy-2'-deoxyguanosine (below 400 ppm) in the rat colon. Moreover PhIP-DNA adducts were not formed at the lowest dose (below 0.01 ppm). Thus, the dose required to initiate ACF is approximately 5000 times higher than that needed for adduct formation. The results imply a no-observed effect level (existence of a threshold) for colon carcinogenesis by a genotoxic carcinogen.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Carcinogens; Colon; Colonic Neoplasms; Deoxyguanosine; DNA Adducts; Dose-Response Relationship, Drug; Imidazoles; Male; Mutagenicity Tests; Mutagens; No-Observed-Adverse-Effect Level; Precancerous Conditions; Rats; Rats, Inbred F344

Chronic inflammation may contribute to cancer risk through the accumulation of specific products as a result of DNA damage. The role of free radical mediated oxidative DNA damage during inflammation was determined in patients with ulcerative colitis by measuring 8-hydroxydeoxyguanosine (8-OHdG).. Patients with ulcerative colitis were compared according to age, gender, duration and extent of disease, endoscopic and histologic activity, presence or absence of dysplasia/cancer, and biochemical parameters of inflammation. Patients with sporadic colon cancer and irritable bowel syndrome served as controls. Levels of 8-OHdG were assessed by high pressure liquid chromatography with electrochemical detection (mean number of adducts/10(5) dG residues).. Patients with ulcerative colitis and dysplasia had significantly higher mucosal 8-OHdG concentrations (P = 0.011). 8-OHdG concentrations were significantly higher in older patients (P = 0.010), patients with long-standing disease (P = 0.015), active endoscopic (P = 0.006) or histologic disease (P = 0.003). Covariance analysis showed significant effect of dysplasia on 8-OHdG levels: values higher than 100 adducts/10(5) dG had a diagnostic value of 80.9% (SE 6.2%).. Oxidative DNA damage accumulates with the duration of the disease in ulcerative colitis reaching maximal increase if dysplastic lesions are found with possible implications for mutagenic and carcinogenic progression.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Case-Control Studies; Colitis, Ulcerative; Colonic Neoplasms; Deoxyguanosine; DNA Damage; Female; Humans; Intestinal Mucosa; Male; Middle Aged; Severity of Illness Index

Humans may be exposed to 2-amino-3,8-dimethylimidazo[4,5-f ]quinoxaline (MeIQx) at low doses during the period of gestation and lactation, and thereafter throughout life. The current study was designed to examine the possibility that early exposure may increase the risk of liver tumor development and related genetic changes. Male and female F344 rats were therefore administered MeIQx in diet (1, 10 and 100 ppm) for 4 weeks before mating and also during gestation and lactation. We also examined the carcinogenic risk of low-dose maternal and post-weaning exposure (MeIQx at doses of 1 and 10 ppm). Surviving male F1 rats were sacrificed under ether anesthesia at 19 weeks of age for analyses of glutathione S-transferase placental form-positive foci in the liver and aberrant crypt foci in the colon, as putative preneoplastic lesions. Transplacental and trans-breast milk exposure to MeIQx did not enhance development of the lesions, and levels of cell proliferation in the liver also did not differ from control values. However, excretion of MeIQx into breast milk and transfer to the fetus and offspring were observed with resultant hepatic MeIQx-DNA adducts and 8-hydroxy-2'-deoxyguanosine formation. Thus, our data suggest that maternal exposure to MeIQx during the period of pregnancy and lactation may not increase the risk of hepatocarcinogenesis in male offspring, despite causing genetic damage. If this result can be extrapolated to humans, exposure to MeIQx may not increase carcinogenic risk in offspring at usual human exposure levels.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Carcinogens; Cell Proliferation; Colon; Colonic Neoplasms; Deoxyguanosine; Diet; DNA Adducts; Female; Glutathione Transferase; Humans; Lactation; Liver; Liver Neoplasms, Experimental; Male; Milk, Human; Placenta; Precancerous Conditions; Pregnancy; Quinoxalines; Rats; Rats, Inbred F344

We have recently shown that immunodeficient (SCID) mice, which lack functional T and B cells, are highly susceptible to low dose site specific induction of colon aberrant crypt foci (ACF), surrogates for colon tumors, by 2-amino-3-methylimidazo[4,5-f ]quinoline (IQ). To test whether long-term exposure to a high dose in the diet might prove carcinogenic to the SCID mouse colon, in contrast to other mice strains tested to date, the compound was administered at 300 p.p.m. in the diet to female 6-7-week-old SCID mice for 32 weeks. IQ induced high numbers of ACF, hyperplastic polyps, dysplasia, and colon adenomas, as well as hepatocellular altered foci and liver adenomas. Induction of colon tumors did not correlate with the main sites where ACF developed, the proximal colon, however, being seen mainly in the mid and distal colon. Induction of colon tumors correlated significantly with the incidence of dysplasia, crypt height, the mitotic index, cell proliferation and numbers of 8-hydroxydeoxyguanosine (8-OHdG)-positive cells in the colon crypt, particularly in mid and distal colon. Administration of 20% omega-6 polyunsaturated fatty acids (corn oil), omega-3 polyunsaturated fatty acids (perilla oil), or monounsaturated fatty acids (olive oil) simultaneously with IQ in the diet resulted in: (i) inhibition of colon and liver tumor induction by corn and perilla oil, whereas olive oil showed no effects; (ii) no reduction in total numbers of ACF by corn oil or perilla oil but significant suppression in the olive oil treated group; (iii) inhibition of tumor development particularly by omega-3 polyunsaturated fatty acids in perilla oil, correlating significantly with decreased cell proliferation in both colon and liver and a marked decrease in crypt heights and mitotic indices. Selective reduction in the numbers of 8-OHdG-positive nuclei, mainly in the middle and distal colon crypts, was also found to correlate with tumor inhibition. Thus, the results indicate carcinogenicity of IQ in the colon of the SCID mouse and preventive effects of polyunsaturated fatty acids.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Apoptosis; Body Weight; Carcinogenicity Tests; Carcinogens; Cell Division; Colonic Neoplasms; Deoxyguanosine; Disease Models, Animal; Fatty Acids; Female; Incidence; Intestinal Mucosa; Kidney; Liver; Liver Neoplasms; Mice; Mice, SCID; Mitosis; Organ Size; Quinolines

We examine whether the level of 8-oxo-2'-deoxyguanosine (8-oxodGuo) in lymphocytes DNA is higher in colon cancer when compared to the control group. Factors that may influence oxidative stress such as antioxidant vitamins and uric acid were also determined. Blood samples were obtained from a control group of 55 healthy persons and 43 colon cancers. 8-OxodGuo level and the vitamins concentration were measured by high-performance liquid chromatography. The levels of 8-oxodGuo were significantly higher whereas the concentrations of the vitamins and uric acid were significantly lower in colon cancer patients than in control group. Therefore, the decreased concentration of antioxidant vitamins together with lower amount of uric acid may be responsible for the formation of pro-oxidative environment in blood of colorectal carcinoma patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Aged, 80 and over; Ascorbic Acid; Chromatography, High Pressure Liquid; Colonic Neoplasms; Deoxyguanosine; DNA; Female; Humans; Lymphocytes; Male; Middle Aged; Oxidative Stress; Uric Acid; Vitamin A; Vitamin E

Heterocyclic aromatic amines (HAA) are initiating agents of colon carcinogenesis in animals and are suspected in the aetiology of human colon cancer. In the context of prevention, it seems interesting to test possible protective compounds, such as fermented milk, against HAA food carcinogens. Male F344 rats were used in a model of HAA-induced colon carcinogenesis. The HAA, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) (ratio 1:1:1) were administered in food for a 7 week induction period, with a cumulative dose of 250 mg of the HAA, per kg body weight. Four different diets were given to four rat groups: supplemented with 20% water, 30% non-fermented milk, 30% Bifidobacterium animalis DN-173 010 fermented milk and 30% Streptococcus thermophilus DN-001 158 fermented milk. Fecal mutagenicity was quantified during the induction period. At the end of the treatment, DNA lesion levels were determined in the liver and colon using the number of 8-oxo-7,8-dihydro-2'desoxyguanosine (8-oxodGuo) oxidized bases, "3D Test" and comet assay. The metabolic activity of hepatic and colon cytochrome P450 (CYP450) 1A1 and 1A2 was also evaluated. Aberrant colon crypts were scored, 8 weeks after the last HAA treatment. The results showed that dairy products decreased the incidence of aberrant crypts in rats: 66% inhibition with the milk-supplemented diet, 96% inhibition with the B.animalis fermented milk-supplemented diet and 93% inhibition with the S.thermophilus fermented milk-supplemented diet. Intermediate biomarkers showed that there was a decrease in HAA metabolism, fecal mutagenicity and colon DNA lesions. These results demonstrate the early protective effect of milk in the carcinogenesis process. This effect being more pronounced in the case of milk fermented by lactic acid bacteria.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Biomarkers, Tumor; Colon; Colonic Neoplasms; Comet Assay; Dairy Products; Deoxyguanosine; Diet; DNA Damage; Feces; Fermentation; Heterocyclic Compounds; Liver; Male; Milk; Mutagenesis; Rats; Rats, Inbred F344; Weight Gain

This study was done to discover the underlying mechanism of the inhibitory effect of sericin against colon tumorigenesis. Mice were fed a diet with 30 g/kg sericin for 115 d, and given a weekly injection of 1,2-dimethylhydrazine (10 mg/kg body weight) for the initial 10 wk. Dietary supplemental sericin caused a 62% reduction in the incidence of colonic adenoma (P<0.05), but did not affect the incidence of colonic adenocarcinoma. Sericin intake significantly reduced the number of colon adenomas. Consumption of sericin significantly reduced the BrdU labeling index of colonic proliferating cells and the expression of colonic c-myc and c-fos. The levels of colonic 8-hydroxydeoxyguanosine, 4-hydroxynonenal, and inducible nitric oxide synthase protein were significantly suppressed by sericin. The results suggest that dietary sericin suppresses the development of colon tumors by reducing oxidative stress, cell proliferation, and nitric oxide production.

Topics: 1,2-Dimethylhydrazine; 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Adenoma; Aldehydes; Animals; Apoptosis; Carcinogens; Cell Division; Colonic Neoplasms; Deoxyguanosine; Immunohistochemistry; Intestinal Mucosa; Male; Mice; Mice, Inbred ICR; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oxidative Stress; Peptides, Cyclic; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-myc; Sericins

This study examined the effects of lyophilized black raspberries (BRB) on azoxymethane (AOM)-induced aberrant crypt foci (ACF), colon tumors, and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in male Fischer 344 rats. AOM was injected (15 mg/kg body wt i.p.) once per week for 2 wk. At 24 h after the final injection, AOM-treated rats began consuming diets containing 0%, 2.5%, 5%, or 10% (wt/wt) BRB. Vehicle controls received 5% BRB or diet only. Rats were sacrificed after 9 and 33 wk of BRB feeding for ACF enumeration and tumor analysis. ACF multiplicity decreased 36%, 24%, and 21% (P < 0.01 for all groups) in the 2.5%, 5%, and 10% BRB groups, respectively, relative to the AOM-only group. Total tumor multiplicity declined 42%, 45%, and 71% (P < 0.05 for all groups). Although not significant, a decrease in tumor burden (28%, 42%, and 75%) was observed in all BRB groups. Adenocarcinoma multiplicity decreased 28%, 35%, and 80% (P < 0.01) in the same treatment groups. Urinary 8-OHdG levels were reduced by 73%, 81%, and 83% (P < 0.01 for all groups). These results indicate that BRB inhibit several measures of AOM-induced colon carcinogenesis and modulate an important marker of oxidative stress in the Fischer 344 rat.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Adenoma; Animals; Anthocyanins; Anticarcinogenic Agents; Azoxymethane; Calcium; Cholesterol; Colonic Neoplasms; Coumaric Acids; Deoxyguanosine; Diet; Ellagic Acid; Freeze Drying; Fruit; Oxidative Stress; Rats; Rats, Inbred F344; Rosaceae; Sitosterols

The effect of black tea polyphenols on 1,2-dimethylhydrazine (DMH)-induced oxidative DNA damage in rat colon mucosa has been investigated. Fischer 344 rats were treated orally with thearubigin (TR) or theafulvin (TFu) for 10 days (40 mg/kg), injected ip with DMH (20 mg/kg) or saline and sacrificed 24 hr after DMH administration. The levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) were measured in colonic mucosa DNA and expressed as a ratio relative to 2'-deoxyguanosine (2dG). Control rat mucosa had 8-OHdG values of 1.12 +/- 0.14/10(5) dG (mean +/- SEM, n=11), whereas DMH-treated rats significantly higher values (1.52 +/- 0.14/10(5) dG, n=26, P<0.05). Pretreatment of rats with TR had significantly inhibited DMH-induced oxidative DNA damage 0.99 +/- 0.09/10(5) dG, n=10, P<0.05) and a similar, although less marked, effect was observed with TFu (1.15 +/- 0.19/10(5), n=9, P=0.06). These findings confirm that DMH causes oxidative DNA damage in the colon mucosa of rats and demonstrate that this effect is prevented by the consumption of complex polyphenols from black tea.

Topics: 1,2-Dimethylhydrazine; 8-Hydroxy-2'-Deoxyguanosine; Alkylating Agents; Animals; Antioxidants; Carcinogens; Catechin; Chromatography, High Pressure Liquid; Colonic Neoplasms; Deoxyguanosine; DNA Damage; Flavonoids; Intestinal Mucosa; Male; Phenols; Phytotherapy; Polymers; Polyphenols; Rats; Rats, Inbred F344; Tea

Phosphatidylcholine hydroperoxide (PCOOH) measured using a chemiluminescence detector to examine colonic mucosal lipid hyperoxidation increased after injection of 1,2-dimethylhydrazine and green tea extract (GTE), which we previously showed inhibited carcinogenesis and oxidative DNA damage in the gastrointestinal tract. Therefore, the hyperoxidation of membrane phospholipids reflected well the degree of DNA damage and carcinogenic alteration, and may be a useful intermediate biomarker for initiation of carcinogenesis.

Topics: 1,2-Dimethylhydrazine; 8-Hydroxy-2'-Deoxyguanosine; Animals; Colonic Neoplasms; Deoxyguanosine; Dimethylhydrazines; Lipid Peroxidation; Male; Phosphatidylcholines; Plant Extracts; Rats; Rats, Sprague-Dawley; Tea