8-hydroxy-2--deoxyguanosine and Colorectal-Neoplasms

Oxidative stress refers to the imbalance between the generation of reactive oxygen species (ROS) and their scavenging by the inherent antioxidant defenses of the cell. The abnormal accumulation of ROS is the underlying pathology in a variety of human diseases such as neurodegenerative phenomena, inflammatory diseases, metabolic disorders, and cancer. The mechanism by which abnormal accumulation of ROS contributes to pathological conditions involves damage or oxidative modification of biomolecules, such as nucleotides, lipids, and proteins. One of the most common targets of ROS is DNA, modifications of which have been associated with cellular transformation and genome instability. There are a number of experimental strategies to assess oxidative modification of DNA bases, such as chromatography-based assays and indirect immunofluorescence. While the former provide quantitative assessment of oxidative modification, the latter is a much simpler assay for qualitative determination of DNA base modification in very small sample sizes. Here, we present a brief background of the various methodologies for the assessment of a specific oxidative DNA modification, 8oxodG, and present a more detailed account of the indirect immunofluorescence assay.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Antibodies, Monoclonal; Biomarkers; Cell Line, Tumor; Colorectal Neoplasms; Deoxyguanosine; DNA; DNA Damage; Fluorescent Antibody Technique; Humans; Hydrogen Peroxide; Microscopy, Confocal; Neoplasms; Oxidation-Reduction; Oxidative Stress; Reactive Oxygen Species

Brazilian propolis, a folk medicine, is used worldwide as an alternative medicine to prevent colon cancer. The objective of the study was to test in a small pilot biomarker study in a high-risk group the safety and efficacy of propolis for colon cancer prevention, which has not been evaluated in humans.. Subjects with adenoma polyps recently removed from the colon were randomly assigned to a propolis group of 15 and a placebo group of 16. In a double-blind study, the propolis group received capsules containing 165 μmol artepillin C and 150 μmol other polyphenols per day for 3 months. Prior to and at the end of the experiments, their blood was analyzed using biochemical tests, and specimens from the normal-appearing sigmoid colon mucosa were biopsied endoscopically to examine the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and mRNA expressions of proliferating cell nuclear antigen, cyclin D1, and Bax.. Propolis extract significantly increased the mRNA level of cyclin D1 in the sigmoid colon mucosa, and the other biomarkers remained unchanged. Blood biochemical tests showed significantly higher activity of creatine phosphokinase (CPK), 143 ± 52 units/ml in the propolis group and 104 ± 38 units/ml in the placebo group (p = 0.026), at the end of the study. The increase in CPK activity in the propolis group was due to the increase of the myocardial band form of CPK. On the other hand, laxative treatment prior to endoscopic biopsy significantly increased 8-OHdG levels.. The results from our pilot study did not provide evidence that Brazilian propolis was effective in preventing changes occurring during early stages of colon cancer. In contrast, propolis may have detrimental side effects on muscle tissue, including myocardial cells.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenomatous Polyps; Aged; Biomarkers; Brazil; Colon; Colorectal Neoplasms; Creatine Kinase; Cyclin D1; Deoxyguanosine; Double-Blind Method; Female; Humans; Intestinal Polyps; Male; Middle Aged; Phenylpropionates; Pilot Projects; Plant Extracts; Polyphenols; Proliferating Cell Nuclear Antigen; Propolis; RNA, Messenger

Recent in vitro and animal studies have suggested that the cytotoxicity of 5-fluorouracil and oxaliplatin is linked to increased formation of reactive oxygen species (ROS). This prospective study was undertaken to examine the generation of oxidative stress, in 106 colorectal cancer patients, by 5-fluorouracil and oxaliplatin combination (FOLFOX) therapy as measured by urinary excretion of 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydro-guanosine (8-oxoGuo).. The amounts of 8-oxoGuo and 8-oxodG were measured in 3 spot urine samples from 106 patients by using ultra performance liquid chromatography and tandem mass spectrometry. Furthermore, we collected information on other clinical and demographic variables hypothesized to be associated with oxidative stress. Repeated measures linear mixed models were used to model the relationship between urinary concentrations of 8-oxoGuo and 8-oxodG and the treatment effect and the other variables.. The analysis showed that chemotherapy increased the excretion of 8-oxoGuo and 8-oxodG around 15% (P < 0.0001 and P = 0.02, respectively) though there was a significant interaction with CRP levels. Additionally, we found that sex, smoking status, age, and c-reactive protein were related to urinary excretion of 8-oxoGuo and 8-oxodG in colorectal cancer patients.. These results indicate that FOLFOX induces ROS in patients and that ROS-generating mechanisms interact.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Antineoplastic Combined Chemotherapy Protocols; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Deoxyguanosine; Drug Administration Schedule; Female; Fluorouracil; Guanosine; Humans; Male; Neoplasm Staging; Organoplatinum Compounds; Oxaliplatin; Oxidation-Reduction; Oxidative Stress; Prospective Studies; Tandem Mass Spectrometry; Treatment Outcome

Oxidative DNA damage results from DNA adducts such as 8-oxo-7, 8 dihydro-2'-deoxyguanosine (8-oxo-dG), which is a pro-mutagenic lesion. No known association between 8-oxo-dG, disease progression and survival exists in colorectal cancer (CRC). We examined levels of 8-oxo-dG in sporadic CRC to determine its relationship with pathological stage and outcome. A total of 143 CRC patients and 105 non-cancer patients were studied. Nuclear and cytoplasmic 8-oxo-dG was assessed using immunohistochemistry. Double immunofluorescence using 8-oxo-dG and manganese superoxide dismutase (MnSOD) antibodies localised cytoplasmic 8-oxo-dG. Apoptosis was detected using TUNEL. Nuclear staining levels were similar in tumour tissue and matched normal mucosa in both epithelial (P=0.22) and stromal (P=0.85) cells. Epithelial cytoplasmic staining was greater in tumour tissue (P<0.001). Double immunofluorescence localised cytoplasmic 8-oxo-dG to mitochondria. Epithelial and stromal nuclear 8-oxo-dG decreased with local disease spread, but highest levels were found in distant disease (P<0.01). Survival was related to epithelial nuclear and stromal staining in normal mucosa (P<0.001) and tumour (P<0.01) but was unrelated to cytoplasmic staining. Normal control cells in tissue from cancer patients with high levels of 8-oxo-dG failed to undergo cell death. 8-oxo-dG may be an important biomarker of disease risk, progression and survival for CRC patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adolescent; Adult; Aged; Aged, 80 and over; Apoptosis; Biomarkers, Tumor; Case-Control Studies; Cell Nucleus; Colon; Colorectal Neoplasms; Cytoplasm; Deoxyguanosine; Disease Progression; Female; Fluorescent Antibody Technique; Humans; Immunoenzyme Techniques; In Situ Nick-End Labeling; Male; Middle Aged; Rectum; Superoxide Dismutase; Survival Rate; Tissue Array Analysis; Young Adult

Oxidative DNA damage is believed to be involved in tumor formation and may be an important biomarker for malignant transition or relapse. A decrease of such damage has been observed in human and animal studies following dietary intervention and/or changes in lifestyle such as physical exercise at different levels of intensity. The purpose of this study was to carry out a clinical trial comparing the effects of a short-term (2 weeks) exercise program of moderate intensity (0.3-0.4 x maximal exercise capacity) (MI) versus high intensity (0.5-0.6 x maximal exercise capacity) (HI) on individual urinary excretion of 8-oxo-dG before and after completion of the exercise programs.. In this short-term, prospective and randomized trial, 19 patients with colorectal cancer were allocated to the MI group following primary therapy and 29 to the HI group. Urinary 8-oxo-dG excretion concentration was determined by a highly sensitive detection method using high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS). Concentrations were determined immediately before and after completion of the exercise programs.. Using HPLC-ESI-MS, it was shown that MI exercise significantly reduced urinary 8-oxo-dG excretion levels from 8.47 +/- 1.99 to 5.81 +/- 1.45 (ng/mg creatinine, mean +/- SE, p = 0.02), whereas HI exercise resulted in a non-significant increase from 5.00 +/- 1.31 to 7.11 +/- 1.63 (ng/mg creatinine, p = 0.18). Clinical characteristics (gender, age, body mass index (BMI), diet, chemotherapy/irradiation) were not associated/correlated with urinary 8-oxo-dG levels.. By using HPLC-ESI-MS it was shown that short-term MI exercise after primary therapy in patients with colorectal cancer was associated with lower levels of urinary 8-oxo-dG, suggesting decreased oxidative DNA damage. In contrast, HI exercise tended to increase DNA damage. A prospective trial is now warranted to prove that reduced oxidative DNA damage lowers the risk of relapse of colorectal cancer in treated patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Biomarkers, Tumor; Carcinoma; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Combined Modality Therapy; Deoxyguanosine; DNA Damage; Exercise Therapy; Female; Follow-Up Studies; Humans; Male; Middle Aged; Oxidative Stress; Prospective Studies; Reproducibility of Results; Spectrometry, Mass, Electrospray Ionization; Time Factors; Treatment Outcome

Oxidative stress (OS) and inflammation are known to play an important role in colorectal cancer (CRC). This study analyzed tumor, inflammatory and OS markers in CRC patients and in a control group. In addition, the evolution of these markers was evaluated after one-year of follow-up treatment. This was a longitudinal and prospective, observational study in 80 CRC patients who were candidates for tumor resection surgery and/or chemo-radiotherapy treatment and a healthy control group (n = 60). Subsequently, catalase (CAT), reduced glutathione (GSH), oxidized glutathione (GSSG) and GSSG/GSH ratio in serum and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and F2-IsoProstanes (F2-IsoPs) in urine at 1, 6 and 12 months after treatment was analyzed. Tumor markers (CEA and CA 19.9), as well as inflammatory markers-leukocytes, neutrophils, neutrophil/lymphocyte (N/L) index, platelets, fibrinogen, C-reactive protein (CRP), and interleukin 6 (IL6)- were also analyzed. As expected, levels of CEA and CA 19.9 and markers of inflammation, except CRP, were significantly higher in CRC compared to the control group. Regarding OS markers, a decrease in CAT and GSH and an increase in GSSG, GSSG/GSH ratio, 8-oxodG and F2-IsoPs were found in CRC patients compared to healthy controls at baseline. After treatment, an improvement of their inflammation profile was accompanied by a progressive recovery of antioxidant enzyme activities and the decline of oxidative byproducts both in serum and urine. Based on the results obtained, we propose the assay of urinary 8-oxodG and F2-IsoPs, as well as serum CAT, GSH, GSSG as a marker for the evaluation of OS and the clinical follow-up of CRC patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Antioxidants; Biomarkers; Colorectal Neoplasms; Deoxyguanosine; Follow-Up Studies; Glutathione; Glutathione Disulfide; Humans; Inflammation; Oxidative Stress; Prospective Studies

Oxidative stress (OS) and inflammation are known to play an important role in chronic diseases, including cancer, and specifically colorectal cancer (CRC). The main objective of this study was to explore the diagnostic potential of OS markers in patients with CRC, which may translate into an early diagnosis of the disease. To do this, we compared results with those in a group of healthy controls and assessed whether there were significant differences. In addition, we explored possible correlations with the presence of tumors and tumor stage, with anemia and with inflammatory markers used in clinical practice. The study included 80 patients with CRC and 60 healthy controls. The following OS markers were analyzed: catalase (CAT), reduced glutathione (GSH) and oxidized glutathione (GSSG) in serum; and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and F2-isoprotanes in urine (F2-IsoPs). Tumor markers (CEA and CA 19.9), anemia markers (hemoglobin, hematocrit and medium corpuscular volume) and inflammatory markers (leukocytes, neutrophils, N/L index, platelets, fibrinogen, C-reactive protein, CRP and IL-6) were also determined. Comparison of means between patients and controls revealed highly significant differences for all OS markers, with an increase in the prooxidant markers GSSG, GSSG/GSH ratio, 8-oxodG and F2-IsoPs, and a decrease in the antioxidant markers CAT and GSH. Tumor and inflammatory markers (except CRP) correlated positively with GSSG, GSSG/GSH ratio, 8-oxodG and F2-IsoPs, and negatively with CAT and GSH. In view of the results obtained, OS markers may constitute a useful tool for the early diagnosis of CRC patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Antioxidants; C-Reactive Protein; Carcinoembryonic Antigen; Catalase; Colorectal Neoplasms; DNA Damage; Fibrinogen; Glutathione; Glutathione Disulfide; Humans; Interleukin-6; Oxidative Stress

Many important human diseases, and especially cancer, have been related to the overproduction of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG). This molecule is a product of oxidative stress processes over nucleophilic bases in DNA. In this work, an aptasensor for the rapid, selective and accurate detection of this oncomarker is presented. The aptasensor consists of a nanoporous anodic alumina material loaded with a dye and is functionalized with an aptamer-based "molecular gate". In the presence of target 8-oxo-dG, the capping aptamer displaces from the surface due to the high affinity of the analyte with the capping aptamer, thus inducing delivery of the preloaded fluorescent dye. In contrast, in the absence of 8-oxo-dG, a poor payload delivery is accomplished. This aptamer-based nanodevice has great sensitivity for 8-oxo-dG, resulting in a LOD of 1 nM and a detection time of ca. 60 min. Moreover, the aptasensor is able to accurately detect 8-oxo-dG in unmodified urine and serum without pre-concentration treatments. This diagnostic tool is validated in a set of 38 urine and serum samples from patients diagnosed of colorectal cancer and control patients. These samples are also analyzed using a standardized and specific ELISA kit. The aptasensor displays excellent sensitivity (95.83/100%) and specificity (80/100%) for 8-oxo-dG detection in serum and urine samples, respectively. Our results may serve as a basis for the development of generalized fluorogenic diagnostic platforms for the easy diagnosis of cancer in biofluids as well as for monitoring therapeutic treatments and detection of relapses without the use of expensive equipment or trained personnel.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aluminum Oxide; Colorectal Neoplasms; Deoxyguanosine; Humans; Nanopores

Chemotherapy for colorectal cancer may lower muscle protein synthesis and increase oxidative stress. We hypothesize that chemotherapy may worsen plasma amino acids (AAs) and markers of oxidative stress (MOS). Therefore, this study aimed to document plasma AAs and MOS before, during and after chemotherapy in colorectal cancer (CRC) surgery patients. Fourteen normal-weight CRC patients were enrolled one month after surgery and scheduled for oxaliplatin-fluoropyrimidine combination (XELOX) therapy. Venous blood samples for AA and MOS (malondialdehyde, MDA; 8-hydroxy-2'-deoxyguanosine, 8-OHdG) measurements were drawn in fasting patients before each oxaliplatin infusion at initiation (A), 1 month (B) and 3 months (C) of the therapy, and after XELOX had finished (6 months, D). The results showed that during XELOX therapy (from phase B to phase D), in comparison to baseline (phase A), the branched chain amino acid/essential amino acid ratio, branched chain amino acids expressed as a percentage of total AAs, and arginine expressed as a percentage of total AAs significantly decreased (

Topics: 8-Hydroxy-2'-Deoxyguanosine; Amino Acids; Antineoplastic Combined Chemotherapy Protocols; Arginine; Capecitabine; Colectomy; Colorectal Neoplasms; Fasting; Female; Humans; Longitudinal Studies; Male; Malondialdehyde; Middle Aged; Oxaloacetates; Oxidative Stress; Pilot Projects; Postoperative Period; Prospective Studies

Prognosis of metastatic colorectal cancer (mCRC) patients nowadays is an important subject in the field of oncology. R0-resection of colon with primary tumor and liver metastasis remains the only treatment which significantly improves survival rate. However, recent experimental data show that surgical trauma can indirectly stimulate tumor growth due to mitochondrial dysfunction and unregulated superoxide radical (O2-) generation.. To study the clinical significance of 8-oxo-2'-deoxyguanosine (8-oxodGu) marker, to assess the oncological effects of warm ischemia of liver parenchyma on disease prognosis in patients with mCRC.. 69 urine 24-hour volume tests of patients with mCRC and 17 healthy individuals were studied. Urine 8-oxodGu level was measured using spectrophotometric method with pre-solid phase DNA extraction. The energy system and hepatocyte detoxification system state, levels of O2- in tumor tissue were determined using the method of electron paramagnetic resonance (EPR) and SpinTraps technology at room temperature. Experiments were carried out on a computerized EPR spectrometer RE-1307. EPR spectra were recorded at temperature of liquid nitrogen (196C) in paramagnetically pure quartz dewar on a computerized spectrometer PE-1307 with resonator H011. Error of the method of spectrum integration and spread of spectrum reproduction of one sample was not more than 3%.. The average level of marker in healthy individuals was 0.244 day, whereas before the resection and on day 3 after the R0-resection of liver in mCRC patients was 3.42 day and 2.12 day (p < 0.05), respectively. On day 3 after the liver resection due to its metastatic lesions with a total duration of warm ischemia period < 30 min and > 30 min have had marker at level 2.108 day and 2.9883 day (p < 0.0001), respectively. The volume of metastatic tissue significantly and directly correlated with the level of urine 8-oxodGu (R. Warm liver ischemia (> 30 min), long-term surgical intervention ( 300 min) and metastatic tissue volume ( 12 cm

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Biomarkers; Colorectal Neoplasms; Deoxyguanosine; DNA; Female; Humans; Male; Middle Aged; Neoplasm Metastasis; Neoplasm Staging; Oxidation-Reduction; Prognosis

Reactive oxygen species (ROS) accumulation is known to induce carcinogenesis and accelerate cancer progression. 8‑Hydroxydeoxyguanosine (8‑OHdG) is a specific marker of ROS‑mediated DNA damage. Therefore, we analysed 8‑OHdG levels in cancerous and normal tissue DNA via enzyme‑linked immunosorbent assay (ELISA) using 97 tissue specimens obtained from surgically‑treated patients with stage II/III colorectal cancer (CRC). Additionally, 8‑OHdG levels in these tissues were also assessed via quantitative immunohistochemistry (qIHC). To eliminate individual background variables, the ratio of 8‑OHdG levels between cancerous and normal tissues was calculated using both techniques. A comparative analysis demonstrated that the 8‑OHdG ratio in DNA was significantly correlated with both lymph node metastasis and lymphatic invasion. Multivariate analysis revealed that a high 8‑OHdG ratio in DNA was independently correlated with poor prognosis. These results suggest that the 8‑OHdG ratio in DNA reflects ROS‑induced cancer progression. Conversely, a low 8‑OHdG ratio as estimated via qIHC was an independent factor for poor prognosis. In Kaplan‑Meier analysis, the combination of a high 8‑OHdG ratio in DNA (ELISA) and a low 8‑OHdG ratio in cytoplasm (qIHC) was associated with markedly worse patient prognosis than other combinations. Combined evaluation of the 8‑OHdG ratio using ELISA and qIHC may be pivotal for predicting surgical outcomes for patients with stage II/III CRC.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Biomarkers, Tumor; Colon; Colorectal Neoplasms; Cytoplasm; Deoxyguanosine; Disease-Free Survival; DNA, Neoplasm; Enzyme-Linked Immunosorbent Assay; Female; Humans; Kaplan-Meier Estimate; Lymphatic Metastasis; Male; Neoplasm Staging; Predictive Value of Tests; Prognosis

Oxidative stress has been linked to cancer development in previous studies. However, the association between pre-diagnostic oxidatively generated DNA/RNA damage levels and incident cancer has rarely been investigated. Urinary oxidized guanine/guanosine (OxGua) concentrations, including 8-hydroxy-2'-deoxyguanosine, were assessed in 8,793 older adults in a population-based German cohort. 1,540 incident cancer cases, including 207 lung, 196 colorectal, 218 breast and 245 prostate cancer cases were diagnosed during over 14 years of follow-up. Associations of OxGua levels with cancer outcomes were not observed in the total population in multi-variable adjusted Cox regression models. However, in subgroup analyses, colorectal cancer incidence increased by 8%, 9% and 8% with one standard deviation increase in OxGua levels among current non-smokers, female and non-obese participants, respectively. Additionally, among non-smokers, overall and prostate cancer incidences statistically significantly increased by 5% and 13% per 1 standard deviation increase in OxGua levels, respectively. In contrast, OxGua levels were inversely associated with the risk of prostate cancer among current smokers. However, none of the subgroup analyses had p-values below a threshold for statistical significance after correction for multiple testing. Thus, results need to be validated in further studies. There might be a pattern that oxidatively generated DNA/RNA damage is a weak cancer risk factor in the absence of other strong risk factors, such as smoking, obesity and male sex.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Aged, 80 and over; Breast Neoplasms; Colorectal Neoplasms; DNA Damage; Female; Follow-Up Studies; Humans; Incidence; Lung Neoplasms; Male; Middle Aged; Obesity; Oxidative Stress; Prostatic Neoplasms; Risk Factors; Sex Factors; Smoking

Proton radiation is a major component of the radiation field in outer space and is used clinically in radiation therapy of resistant cancers. Although epidemiologic studies in atom bomb survivors and radiologic workers have established radiation as a risk factor for colorectal cancer (CRC), we have yet to determine the risk of CRC posed by proton radiation owing to a lack of sufficient human or animal data. The purpose of the current study was to quantitatively and qualitatively characterize differential effects of acute and fractionated high-energy protons on colorectal carcinogenesis.. Significantly higher intestinal tumor number and grade, along with decreased differentiation, were observed after acute radiation relative to fractionated radiation. Acute protons induced upregulation of β-catenin and Akt pathways with increased proliferative marker phospho-histone H3. Increased DNA damage along with decreased DNA repair factors involved in mismatch repair and nonhomologous end joining were also observed after exposure to acute protons.. We show increased γH2AX, 53BP1, and 8-oxo-dG, suggesting that increased ongoing DNA damage along with decreased DNA repair factors and increased proliferative responses could be triggering a higher number of intestinal tumors after acute relative to fractionated proton exposures in Apc

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; beta Catenin; Carcinogenesis; Cell Differentiation; Cell Proliferation; Colorectal Neoplasms; Cyclin D1; Disease Models, Animal; DNA Breaks, Double-Stranded; DNA End-Joining Repair; DNA Mismatch Repair; Dose Fractionation, Radiation; Female; Gene Expression; Genes, APC; Histones; Immunoblotting; Intestinal Neoplasms; Intestine, Small; Mice; Mice, Inbred C57BL; Neoplasms, Radiation-Induced; Proto-Oncogene Proteins c-akt; Protons; Radiation Dosage; Radiation Exposure; Space Flight; Tumor Suppressor p53-Binding Protein 1; Up-Regulation

An oncogenic role for CHD4, a NuRD component, is defined for initiating and supporting tumor suppressor gene (TSG) silencing in human colorectal cancer. CHD4 recruits repressive chromatin proteins to sites of DNA damage repair, including DNA methyltransferases where it imposes de novo DNA methylation. At TSGs, CHD4 retention helps maintain DNA hypermethylation-associated transcriptional silencing. CHD4 is recruited by the excision repair protein OGG1 for oxidative damage to interact with the damage-induced base 8-hydroxydeoxyguanosine (8-OHdG), while ZMYND8 recruits it to double-strand breaks. CHD4 knockdown activates silenced TSGs, revealing their role for blunting colorectal cancer cell proliferation, invasion, and metastases. High CHD4 and 8-OHdG levels plus low expression of TSGs strongly correlates with early disease recurrence and decreased overall survival.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Autoantigens; Cell Movement; Cell Proliferation; Clustered Regularly Interspaced Short Palindromic Repeats; Colorectal Neoplasms; Deoxyguanosine; Disease-Free Survival; DNA (Cytosine-5-)-Methyltransferases; DNA Damage; DNA Glycosylases; DNA Methylation; Down-Regulation; Enhancer of Zeste Homolog 2 Protein; Epigenetic Repression; Gene Expression Regulation, Neoplastic; Gene Silencing; Genes, Tumor Suppressor; HCT116 Cells; Histocompatibility Antigens; Histone-Lysine N-Methyltransferase; Humans; Kaplan-Meier Estimate; Mi-2 Nucleosome Remodeling and Deacetylase Complex; Mice, Inbred BALB C; Mice, Nude; Neoplasm Metastasis; Oxidative Stress; Proportional Hazards Models; Receptors for Activated C Kinase; Receptors, Cell Surface; RNA Interference; Time Factors; Transcription, Genetic; Transfection; Tumor Suppressor Proteins

Excessive alcohol consumption is a risk factor associated with colorectal cancer; however, some studies have reported that moderate alcohol consumption may not contribute additional risk for developing colorectal cancer while others suggest that moderate alcohol consumption provides a protective effect that reduces colorectal cancer risk. The purpose of this study was to determine the effects of moderate voluntary alcohol (20% ethanol) intake on alternate days for 3 months in outbred Wistar rats on risk factors associated with colorectal cancer development. Colonic gene expression of cyclooxygenase-2, RelA, 8-oxoguanine DNA glycosylase 1, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase M1, and aldehyde dehydrogenase 2 were determined. Blood alcohol content, liver function enzyme activities, and 8-oxo-deoxyguanosine DNA adducts were also assessed. Alcohol-treated rats were found to have significantly lower 8-oxo-deoxyguanosine levels in blood, a marker of DNA damage. Alanine aminotransferase and lactate dehydrogenase were both significantly lower in the alcohol group. Moderate alcohol significantly decreased cyclooxygenase-2 gene expression, an inflammatory marker associated with colorectal cancer risk. The alcohol group had significantly increased glutathione-S-transferase M1 expression, an antioxidant enzyme that helps detoxify carcinogens, such as acetaldehyde, and significantly increased aldehyde dehydrogenase 2 expression, which allows for greater acetaldehyde clearance. Increased expression of glutathione-S-transferase M1 and aldehyde dehydrogenase 2 likely contributed to reduce mucosal damage that is caused by acetaldehyde accumulation. These results indicate that moderate alcohol may reduce the risk for colorectal cancer development, which was evidenced by reduced inflammation activity and lower DNA damage after alcohol exposure.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Alcohol Drinking; Aldehyde Dehydrogenase, Mitochondrial; Animals; Antioxidants; Colitis; Colorectal Neoplasms; Cyclooxygenase 2; Deoxyguanosine; DNA Damage; Ethanol; Gene Expression; Glutathione Transferase; Inflammation; Liver; Male; Rats; Rats, Wistar; Risk Factors

To assess the risk of colorectal cancer in humans with inactivation of NRF2, Nrf2-proficient (Nrf2(+/+) ) and -deficient (Nrf2(-/-) ) mice were exposed to potassium bromate (KBrO3 ) at concentrations of 750 or 1500 ppm for 52 weeks. Neoplastic proliferative lesions were observed in the small intestine and exhibited accumulations of β-catenin and cyclin D1. The lesions had characteristics similar to those in experimental models of human hereditary colorectal cancer. An additional 13-week study was performed to examine the role of Nrf2 in the effects of oxidative stress. Significant increase in combined incidences of preneoplastic and neoplastic lesions in Nrf2(-/-) mice administered high-dose KBrO3 . In the short-term study, although 8-hydroxydeoxyguanosine (8-OHdG) levels in the epithelial DNA of Nrf2(-/-) mice at the high dose were significantly lower than those of the corresponding Nrf2(+/+) mice, the difference was very small. mRNA levels of Nrf2-regulated genes were increased in Nrf2(+/+) mice. Overexpression of cyclooxygenase 2 (COX2) and increased numbers of proliferating cell nuclear antigen (PCNA)-positive cells in the jejunal crypts were observed in Nrf2(-/-) mice administered high-dose KBrO3 . Overall, these data suggested that individuals having single-nucleotide polymorphisms in NRF2 may have a risk of colorectal cancer to some extent.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; beta Catenin; Cell Transformation, Neoplastic; Colorectal Neoplasms; Cyclin D1; Cyclooxygenase 2; Cytokines; Deoxyguanosine; Disease Models, Animal; Female; Gene Expression; Gene Silencing; Humans; Intestinal Mucosa; Intestine, Small; Mice; Mice, Knockout; NF-E2-Related Factor 2; Oxidative Stress; Proliferating Cell Nuclear Antigen

Oxidative DNA damage plays crucial roles in the pathogenesis of numerous diseases including cancer. 8-hydroxy-2'-deoxyguanosine (8-OHdG) is the most representative product of oxidative modifications of DNA, and urinary 8-OHdG is potentially the best non-invasive biomarker of oxidative damage to DNA. Herein, we developed a sensitive, specific and accurate method for quantification of 8-OHdG in human urine. The urine samples were pretreated using off-line solid-phase extraction (SPE), followed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. By the use of acetic acid as an additive to the mobile phase, we improved the UPLC-MS/MS detection of 8-OHdG by 2.7-5.3 times. Using the developed strategy, we measured the contents of 8-OHdG in urine samples from 142 healthy volunteers and 84 patients with colorectal cancer (CRC). We observed increased levels of urinary 8-OHdG in patients with CRC and patients with tumor metastasis, compared to healthy controls and patients without tumor metastasis, respectively. Additionally, logistic regression analysis and receiver operator characteristic (ROC) curve analysis were performed. Our findings implicate that oxidative stress plays important roles in the development of CRC and the marked increase of urinary 8-OHdG may serve as a potential liquid biomarker for the risk estimation, early warning and detection of CRC.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Aged, 80 and over; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Deoxyguanosine; DNA Damage; Female; Humans; Logistic Models; Male; Middle Aged; Oxidative Stress; Reproducibility of Results; Risk Factors; Solid Phase Extraction; Tandem Mass Spectrometry

The aim of this research was to study the levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in tumour tissue samples of colorectal carcinoma based upon immunohistochemical detection and compare those results with patients' outcome.. Tumour blocks of patients surgically treated for colorectal cancer were evaluated by 8-oxodG immunohistochemical staining. The expression was analysed in 500 tumour cells. The percentage of positive cells, as well as staining intensity, was recorded, and Allred score was calculated. For each patient, data of age, gender, tumour size and location, margin status, histologic grade, tumour stage, lymph node status, vascular invasion, overall survival, and therapy protocols were collected. Tumour grade was divided into two groups as low and high grade.. In this study, 146 consecutive patients with primary colorectal carcinoma were included. All data were available for 138 patients, and they were included in this research. There were 83 male and 55 female patients; the median age was 64 years (range 35-87 years). The results showed shorter 5- and 10-year survival in patients with 8-oxodG positive tumour cells (5-year survival, n=138, Mantel-Cox, chi-square 4.116, degree of freedom (df)=1, p<0.05; 10-year survival, n=134, Mantel-Cox, chi-square 4.374, df=1, p<0.05). The results showed a positive correlation between Allred score and high tumour grade (two-tailed Spearman's ρ 0.184; p<0.05), as well as with non-polypoid tumour growth (two-tailed Spearman's ρ 0.198; p<0.05). There was no significant difference of 8-oxodG expression related to age, sex, blood group, size and tumour site, distance from the edge of the resected tumour margin, lymph nodes involvement, and vascular invasion.. In this study, the positive correlation between 8-oxodG presence in the tumour cells, worse clinical outcome, higher tumour grade, and flat morphology was found.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Case-Control Studies; Colorectal Neoplasms; Cytoplasm; Deoxyguanosine; Female; Follow-Up Studies; Humans; Immunoenzyme Techniques; Male; Middle Aged; Mucous Membrane; Neoplasm Grading; Neoplasm Staging; Prognosis; Survival Rate

Oxidative stress linked with chronic inflammation is associated with etiology of the colorectal cancer.. To assess the diagnostic utility of urinary excretion of oxidatively modified DNA bases/nucleoside: 8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and 5-hydroxymethyluracil (5-hmUra).. Seventy-two healthy controls, 15 patients with adenomas and 56 colorectal cancer patients were recruited.. The receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) for all markers tested separately was <0.7. The combination of these modifications showed better diagnostic power (AUC = 0.778 for 8-oxoGua + 8-oxodG)/5hmUra ratio).. Urinary DNA modifications may reflect the oxidative stress/chronic inflammation in colorectal cancer but diagnostic performance for early-detection is moderate.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Biomarkers, Tumor; Colorectal Neoplasms; Female; Guanine; Humans; Male; Middle Aged; Pentoxyl

Oxidative stress is a contributing factor in the carcinogenesis of colorectal cancer. The Nrf2 [nuclear factor (erythroid-derived 2)-like 2; NFE2L2] pathway is one of the major cellular defense mechanisms against oxidative stress. This study investigated the expression of the Nrf2 pathway in colorectal cancer. Formalin-fixed paraffin-embedded tissue arrays consisting of the tumor, adjacent normal, and distant normal tissues from the resected specimens of 83 colorectal cancer patients were subjected to immunohistochemical (IHC) staining with antibodies against Nrf2, kelch-like ECH-associated protein 1 (Keap1), p21, P62, Parkinson protein 7 (Park7), prohibitin, BTB and CNC homology 1 (Bach1), CD34 and 8-hydroxy-2'-deoxyguanosine (8-OHdG). The mean IHC density of each IHC staining was digitally analyzed. The results showed that molecules of the Nrf2 pathway were actively expressed, with different expression profiles among the tumor and normal tissues. The oxidative stress, represented by the mean IHC staining density of 8-OHdG, did not differ but was correlated with the expressions of different Nrf2 pathway molecules to a varied extent in tumor and normal tissues of colorectal cancer. Keap1 [estimate, 0.49; 95% confidence interval (CI), 0.19-0.79] and Bach1 (estimate, 0.24; 95% CI, 0.11-0.38) were significant predictors for the expression of 8-OHdG and had the closest proximity to Nrf2 in the cluster dendrogram of the tumor and distant normal tissues, respectively. Advanced stage (estimate, 14.9; 95% CI, 2.99-26.8) and current smoker (estimate, 15.6; 95% CI, 1.92-29.3) were significant predictors with high estimates for Bach1 in the adjacent and distant normal tissues, respectively. In colorectal cancer, the molecules of the Nrf2 pathway have different expression profiles and a difference in their importance, especially Keap1 and Bach1, related to Nrf2 and oxidative stress among tumor and normal tissues.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Aged; Aged, 80 and over; Basic-Leucine Zipper Transcription Factors; Colorectal Neoplasms; Deoxyguanosine; Fanconi Anemia Complementation Group Proteins; Female; Gene Expression Regulation, Neoplastic; Humans; Image Processing, Computer-Assisted; Immunohistochemistry; Intracellular Signaling Peptides and Proteins; Kelch-Like ECH-Associated Protein 1; Male; Middle Aged; Neoplasm Staging; NF-E2-Related Factor 2; Oxidative Stress; Risk Factors; Signal Transduction; Smoking

Despite some controversy, selenomethionine (SeMet)-mediated protection against colorectal cancer (CRC) might be a very promising non-cytotoxic option. However, responsive molecular targets and underlying mechanisms of SeMet-mediated chemoprevention are still unclear. Our aim was to discover new targets of SeMet-mediated chemoprevention in CRC using proteomics analysis. We found dietary SeMet supplementation before carcinoma initiation effectively suppressed polyp incidence and dysplastic lesions without any adverse effects. To determine chemopreventive targets of SeMet, we employed two-dimensional gel electrophoresis-based proteomics analysis in CRC mouse model. Pretreatment with SeMet apparently modulated the expression of 30 proteins with functions in major processes like chronic inflammation, oxidative stress and apoptosis as discovered through pathway analysis with Pathway Studio software. We validated four proteins selected from pathway analysis including prohibitin, purine nucleoside phosphorylase, annexin 2 and c-reactive protein by immunohistochemistry. 8-Hydroxy-2'-deoxyguanosine (8-OHdG), a known oxidative stress marker, was decreased by SeMet treatment in CRC mice as seen by immunohistochemistry. Further network analysis was done among these new four validated proteins, 8-OHdG and colorectal cancer. These four proteins found by proteomics analysis might be considered as potential chemopreventive biomarkers of SeMet against colon cancer and can help develop and improve approaches in preventive, therapeutic and prognostic aspects.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Apoptosis; Azoxymethane; Biomarkers, Tumor; C-Reactive Protein; Chemoprevention; Colonic Polyps; Colorectal Neoplasms; Deoxyguanosine; Dextran Sulfate; Drug Screening Assays, Antitumor; Electrophoresis, Gel, Two-Dimensional; Immunohistochemistry; Male; Mice; Mice, Inbred ICR; Neoplasm Proteins; Oxidative Stress; Prohibitins; Protein Interaction Maps; Proteome; Proteomics; Repressor Proteins; Selenomethionine; Software

8-hydroxy-2'-deoxyguanosine (8-OHdG) is one of the most abundant oxidatively modified lesions in DNA and is a marker of the oxidative stress. 8-OHdG is a mutagenic lesion and it can mispair with adenine, causing G:C→T: A transversion. Our task was to determine the 8-OHdG level in patients with colorectal adenocarcinoma directly in tumor tissues and corresponding normal mucosa.. Samples of tumor tissues and corresponding normal mucosa of 47 patients undergoing surgery for colorectal cancer were analyzed. DNA was isolated from both tumor and normal tissues. Then, DNA was hydrolyzed to nucleotides using nuclease P1 and alkaline phosphatase. The 8-OHdG and 2'-dG (2'-deoxyguanosine) were determined in hydrolysates by high-performance liquid chromatography (HPLC) with electrochemical (EC) and UV detector.. The levels of 8-OHdG in colorectal adenocarcinoma tissues were higher than in corresponding normal mucosa. No significant differences were shown in 8-OHdG levels in the cancerous and cancer-free tissues between age and sex and stages A/B and C/D of Duke's classification.. 8-OHdG reflects the local oxidative stress in colon adenocarcinoma tissue together with ageing processes, but not the intensity of tumorigenesis itself. Because of many factors that could influence the oxidative modification of DNA bases, its role as a diagnostic and/or prognostic factor in colon adenocarcinoma seems to be limited.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Adult; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Deoxyguanosine; DNA; Female; Humans; Male; Oxidative Stress; Poland; Statistics, Nonparametric

Colitis-associated cancer (CAC) is one of clear examples of inflammation-carcinogenesis sequence, by which the strict control of colitis with potent anti-inflammatory or antioxidative agent offers the chance of cancer prevention. Supported with the facts that Rac1 binds and activates STAT3, which are significantly upregulated in inflammatory bowel disease (IBD) as well as CAC, but 8-hydroxydeoxyguanosine (8-oxo-7,8-dihydrodeoxyguanosine or 8-OHdG) paradoxically can block Rac1 activation and subsequent NADPH oxidase (NOX) inactivation in various inflammation models, we hypothesized that attenuated Rac1-STAT3 and COX-NF-κB pathway by exogenous 8-OHdG administration may ameliorate inflammatory signaling in dextran sodium sulfate (DSS)-induced colitis and can prevent CAC. Before commencing carcinogenesis model, we checked whether exogenous 8-OHdG can alleviate IBD, for which interleukin (IL)-10 knockout mice were designed to ingest 5% DSS for 1 week, and 8-OHdG is given through intraperitoneal route daily. 8-OHdG treatment groups significantly reduced pathologic grade of DSS-induced colitis as well as various inflammatory mediators such as TNF-α, IL-6, COX-2, and iNOS in a dose-dependent manner. To document the cancer prevention effects of 8-OHdG, mice were injected azoxymethane followed by drinking 2.5% DSS for 1 week, after which 8-OHdG-containing diets were given for 20 weeks. As results, mice that consumed 8-OHdG-containing diet significantly reduced both tumor incidence and multiplicity. Rac1 activity and phosphorylated STAT3 level were significantly attenuated in the 8-OHdG-treated group. Significantly decreased levels of malondialdehyde, monocyte chemotactic protein-1, matrix metalloproteinasess, COX-2, NOX4, and β-catenin nuclear accumulation were responsible for cancer prevention effects of exogenous 8-OHdG. In conclusion, we clearly showed cancer-preventive effect of exogenous 8-OHdG against CAC.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Anticarcinogenic Agents; Azoxymethane; Colitis; Colorectal Neoplasms; Deoxyguanosine; Dextrans; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Inflammation; Interleukin-10; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Neoplasms; STAT3 Transcription Factor; Sulfates

Biallelic inactivating germline mutations in the base excision repair MUTYH (MYH) gene have been shown to predispose to MUTYH-associated polyposis (MAP), which is characterized by multiple colorectal adenomas and carcinomas. In this study, we successfully prepared highly homogeneous human MUTYH type 2 recombinant proteins and compared the DNA glycosylase activity of the wild-type protein and fourteen variant-type proteins on adenine mispaired with 8-hydroxyguanine, an oxidized form of guanine. The adenine DNA glycosylase activity of the p.I195V protein, p.G368D protein, p.M255V protein, and p.Y151C protein was 66.9%, 15.2%, 10.7%, and 4.5%, respectively, of that of the wild-type protein, and the glycosylase activity of the p.R154H, p.L360P, p.P377L, p.452delE, p.R69X, and p.Q310X proteins as well as of the p.D208N negative control form was extremely severely impaired. The glycosylase activity of the p.V47E, p.R281C, p.A345V, and p.S487F proteins, on the other hand, was almost the same as that of the wild-type protein. These results should be of great value in accurately diagnosing MAP and in fully understanding the mechanism by which MUTYH repairs DNA in which adenine is mispaired with 8-hydroxyguanine.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenomatous Polyposis Coli; Colorectal Neoplasms; Deoxyguanosine; DNA Glycosylases; DNA Repair; Genetic Variation; Humans; In Vitro Techniques; Kinetics; Mutant Proteins; Recombinant Proteins

This study investigated the connection among the oxidative stress, depression and expression of specific genes involved in DNA-damage signaling pathways in patients with colorectal carcinoma (CRC).. A unique Dukes'C subset of patients with newly diagnosed colorectal adenocarcinoma were assessed using the Hamilton Depression Rating Scale (HAMD), Zung Self-rating Depression Scale (SDS), Zung Self-rating Anxiety Scale (SAS), Symptom Checklist 90 (SCL-90) and other multiple-item questionnaires. Oxidative-stress-related parameters in sera and the expression of genes were monitored during a pretreatment period.. Eighty-two eligibility cases were divided into 2 groups based on an HAMD score cutoff of 20: the mean score was 28.29 in Group A (depression, n=52) and 16.50 in Group B (nondepression, n=30). The serum total antioxidant capacity, catalase, and superoxide dismutase concentrations were lower in Group A, whereas those of nitric oxide and malondialdehyde were higher in Group A. Importantly, the 8-hydroxy-deoxyguanosine level was higher in Group A than in Group B (P<.05). Microarray analysis revealed that the expressions of p34, PA26, and ABL were higher in Group A, whereas those of HRAD51, CR6, and XRCC3 were higher in Group B.. Oxidative stress is capable of causing neuronal toxicity via lipid peroxidation, DNA damage, and abnormalities of gene expression, and therefore is a possible pathogenic mechanism underlying depression in patients with CRC.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Adult; Aged; Colorectal Neoplasms; Depressive Disorder; DNA Damage; Female; Gene Expression Regulation, Neoplastic; Guanine; Humans; Male; Middle Aged; Neoplasm Staging; Oligonucleotide Array Sequence Analysis; Oxidative Stress; Personality Inventory; Psychometrics; Reverse Transcriptase Polymerase Chain Reaction; Risk Factors; Signal Transduction

Since damage to DNA and other cellular molecules by reactive oxygen species ranks high as a major culprit in the onset and development of colorectal cancer, the aim of the present study is to clarify the role of antioxidant seleonoproteins including glutathione peroxidase (GPx), thioredoxin reductase (TXR) and selenoprotein P (SePP), and the effect of oxidative stress on the progression of colorectal cancer. Expression of 14 oxidative stress-related molecules in both tumorous and non-tumorous tissues in 41 patients was examined by immunohistochemistry and Western blot analysis. Expression levels of proteins modified by 4-hydroxy-2-nonenal (4-HNE), malonyldialdehyde (MDA) and 4-hydroxy-2-hexenal (4-HHE), and the positive rate of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in tumorous tissues were much higher than those in non-tumorous tissues. Glutathione (GSH) content in tumor tissues was much lower than that in non-tumorous tissues. Expression level of selenoproteins such as GPx-1, GPx-3, and SePP, which are rapidly degraded during selenium deprivation, was significantly decreased in tumorous tissues, whereas that of GPx-2, which is resistant to selenium deprivation, was increased. Expression of SePP was decreased at stage III and IV, compared to that of stage II. These data suggest that contrasting expression pattern of the antioxidant selenoproteins plays an important role in the progression of colorectal cancer.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Aldehydes; Antioxidants; Apoptosis; Blotting, Western; Cell Proliferation; Colorectal Neoplasms; Deoxyguanosine; Disease Progression; Female; Glutathione; Glutathione Peroxidase; Humans; Immunohistochemistry; Male; Malondialdehyde; Oxidative Stress; Proliferating Cell Nuclear Antigen; Selenoprotein P; Selenoproteins; Superoxide Dismutase; Superoxide Dismutase-1; Thioredoxin-Disulfide Reductase; Tumor Suppressor Protein p53

Measurement of the products of oxidatively damaged DNA in urine is a frequently used means by which oxidative stress may be assessed non-invasively. We believe that urinary DNA lesions, in addition to being biomarkers of oxidative stress, can potentially provide more specific information, for example, a reflection of repair activity. We used high-performance liquid chromatography prepurification, with gas chromatography-mass spectrometry (LC-GC-MS) and ELISA to the analysis of a number of oxidative [e.g., 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), 8-oxo-7,8-dihydro-guanine, 5-(hydroxymethyl)uracil], non-oxidative (cyclobutane thymine dimers) and oligomeric DNA products in urine. We analysed spot urine samples from 20 healthy subjects, and 20 age- and sex-matched cancer patients. Mononuclear cell DNA 8-oxodG levels were assessed by LC-EC. The data support our proposal that urinary DNA lesion products are predominantly derived from DNA repair. Furthermore, analysis of DNA and urinary 8-oxodG in cancer patients and controls suggested reduced repair activity towards this lesion marker in these patients.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Case-Control Studies; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Deoxyguanosine; DNA; Female; Gas Chromatography-Mass Spectrometry; Humans; Leukocytes; Lung Neoplasms; Male; Middle Aged

The oxidized guanine lesion 7,8-dihydro-8-oxo-2'-deoxyguanosine (OG) is highly mutagenic, resulting in G:C to T:A transversion mutations in the absence of repair. The Escherichia coli adenine glycosylase MutY and its human homolog (hMYH) play an important role in the prevention of mutations associated with OG by removing misincorporated adenine residues from OG:A mismatches. Previously, biallelic mutations of hMYH have been identified in a British family (Family N) with symptoms characteristic of familial adenomatous polyposis (FAP), which is typically associated with mutations in the adenomatous polyposis coli (APC) gene. Afflicted members of this family were compound heterozygotes for two mutations in hMYH, Y165C and G382D. These positions are highly conserved in MutY across phylogeny. The current work reveals a reduced ability of the hMYH variants compared to wild-type (WT) hMYH to complement the activity of E.coli MutY in mutY((-)) E.coli. In vitro analysis of the corresponding mutations in E.coli MutY revealed a reduction in the adenine glycosylase activity of the enzymes. In addition, evaluation of substrate affinity using a substrate analog, 2'-deoxy-2'-fluoroadenosine (FA) revealed that both mutations severely diminish the ability to recognize FA, and discriminate between OG and G. Importantly, adenine removal with both the mutant and WT E.coli enzymes was observed to be less efficient from a mismatch in the sequence context observed to be predominantly mutated in tumors of Family N. Interestingly, the magnitude of the reduced activity of the E.coli mutant enzymes relative to the WT enzyme was magnified in the "hotspot" sequence context. If the corresponding mutations in hMYH cause similar sensitivity to sequence context, this effect may contribute to the specific targeting of the APC gene. The lack of complementation of the hMYH variants for MutY, and the reduced activity of the Y82C and G253D E.coli enzymes, provide additional circumstantial evidence that the somatic mutations in APC, and the occurrence of FAP in Family N, are due to a reduced ability of the Y165C and G382D hMYH enzymes to recognize and repair OG:A mismatches.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenine; Adenomatous Polyposis Coli; Base Pair Mismatch; Binding Sites; Colorectal Neoplasms; Deoxyadenosines; Deoxyguanosine; DNA Glycosylases; DNA Primers; DNA Repair; Escherichia coli; Genes, APC; Genetic Complementation Test; Genetic Variation; Guanine; Heterozygote; Humans; In Vitro Techniques; Kinetics; Mutagenesis, Site-Directed; N-Glycosyl Hydrolases; Polymerase Chain Reaction

Unimpaired vitamin D action has been implicated in human cancer prevention. We have previously demonstrated the effectiveness of 1 alpha-dihydroxyvitamin D3 (1,25-D3) to reduce proliferation and increase differentiation in human colon cancer cells. The aim of this study was to investigate, on the one hand, expression of the vitamin D receptor (VDR) and of 25-hydroxyvitamin D(3)-1 alpha-hydroxylase (1 alpha-hydroxylase) in human normal and malignant colonic tissue and, on the other hand, to determine consequences of reduced or lacking VDR action in a VDR knockout mouse model. In low-grade malignancies of the human colon we found increased VDR and 1 alpha-hydroxylase mRNA expression. However, in late-stage high-grade tumors the vitamin D system is severely compromised. In the mouse colon we found an inverse relationship between VDR levels and proliferation in colon descendens, a tissue known to be specifically affected by nutrients during carcinogenesis. Expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, was significantly augmented with complete loss of VDR. These data suggest that genomic 1,25-D(3) action is necessary to protect against nutrition-linked hyperproliferation and oxidative DNA damage.

Topics: 25-Hydroxyvitamin D3 1-alpha-Hydroxylase; 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Animals; Cell Differentiation; Cell Division; Colon; Colorectal Neoplasms; Deoxyguanosine; Disease Models, Animal; DNA Damage; Humans; Immunohistochemistry; Mice; Mice, Knockout; Oxidative Stress; Receptors, Calcitriol; Reverse Transcriptase Polymerase Chain Reaction

The vitamin D receptor knockout (VDR-KO) mouse presents with a skeletal phenotype typical for complete lack of genomic 1,25-dihydroxycholecalciferol effects. Our previous data from human colorectal tissue suggest that the steroid hormone and its receptor may have protective function against tumour progression. In order to investigate the relevance of the vitamin D system for pre-malignant site-directed changes in the colon, we characterized the amount and site-specific distribution of the VDR along the large intestine in wild-type (WT), heterozygote (HT) and KO mice. We also evaluated expression of proliferating cell nuclear antigen (PCNA), of cyclin D1 and the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative stress. In colon ascendens, proliferative cells were dispersed all along the crypt and expression levels of all three markers were high in WT mice. A decrease of VDR expression did not affect expression significantly. In colon descendens, however, fewer proliferative cells were solely located in the lower third of the crypt, and an inverse relationship between VDR reduction, PCNA positivity and cyclin D1 expression was found in HT and KO mice. In parallel to enhanced proliferation a highly significant increase of 8-OHdG positivity occurred. Therefore, the sigmoid colon of VDR-KO mice, fed on an appropriate lactose/calcium-enriched diet to alleviate impaired calcium homeostasis-related phenotypic changes, is an excellent model for investigating induction and prevention of pre-malignant changes in one of the hotspots for human colorectal cancer incidence.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Calcium; Colon; Colorectal Neoplasms; Cyclin D1; Deoxyguanosine; Disease Models, Animal; DNA Damage; Female; Homeostasis; Immunohistochemistry; Male; Mice; Mice, Knockout; Precancerous Conditions; Proliferating Cell Nuclear Antigen; Receptors, Calcitriol

To clarify the role of oxidative stress in aging of colorectal tissue, we analyzed the 8-hydroxydeoxyguanosine (8-OH-dG) levels in colorectal biopsy samples from normal tissue of patients with either colorectal cancer (n = 15) or benign colorectal polyps (n = 40). An age-associated increase of 8-OH-dG was observed (p =.002), although the 8-OH-dG levels were not significantly different between the patients with cancer and those with polyps. These results suggest an increased level of 8-OH-dG formation in human colorectal tissue with age.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adult; Aged; Aged, 80 and over; Aging; Colon; Colonic Polyps; Colorectal Neoplasms; DNA; Guanine; Humans; Intestinal Polyps; Middle Aged; Oxidative Stress; Rectum

8-Hydroxy-2'-deoxyguanosine (8-OHdG) is one of the most abundant oxidatively modified lesions in DNA. Our previous study (Kondo et al, Free Radic. Biol. Med., 27: 401-410, 1999) revealed that human colorectal carcinoma cells are oxidatively stressed based on 8-OHdG determination. To elucidate 8-OHdG metabolism and its clinical significance in colorectal carcinoma, we studied the 8-OHdG repair system in DNA by measuring specific lyase activity and hOGG1 expression using quantitative-competitive reverse transcription-PCR. In addition, we searched for the presence of mutations and single nucleotide polymorphisms of the hOGG1 gene by single-strand conformational polymorphism and sequencing analyses. It was found that 8-OHdG-specific lyase activity and hOGG1 expression were significantly up-regulated in carcinoma, and a proportional association between 8-OHdG levels and either 8-OHdG lyase activity (r = 0.641, P < 0.05) or hOGG1 expression (r = 0.702, P < 0.05) was present. Whereas no difference was detected in the 8-OHdG level between early- and advanced-stage cancer, lyase activity (1.2-fold) and hOG1 expression (1.6-fold) were significantly increased in advanced-stage cancer. No mutation was found in the 25 tumors examined. Three kinds of single nucleotide polymor. phism were observed, including that of codon 326 (Ser/Cys) in exon 7. However, there was no correlation between any of the three polymorphic patterns and either 8-OHdG level or lyase activity. These results suggest that increased 8-OHdG levels in colorectal carcinoma are attributed to increased formation and are maintained by induced 8-OHdG repair activity at appropriate high levels. Our results may offer a unique approach in the development of preventive and therapeutic interventions as well as new insights into the pathogenesis of colorectal carcinoma.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Carbon-Oxygen Lyases; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Deoxyguanosine; Deoxyribonuclease IV (Phage T4-Induced); DNA Mutational Analysis; DNA-(Apurinic or Apyrimidinic Site) Lyase; DNA-Formamidopyrimidine Glycosylase; DNA, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; N-Glycosyl Hydrolases; Polymorphism, Single Nucleotide; Polymorphism, Single-Stranded Conformational; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Neoplasm

Few studies have been conducted focusing on a potential role of reactive oxygen species in tumor cell metabolism. Here we studied human colorectal adenocarcinomas and adenomas to determine whether oxidative stress is imposed on cancer cells in vivo and used specific antibodies against 8-hydroxy-2'-deoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal (HNE)-modified proteins, and 3-nitro-L-tyrosine (3-NT) to determine whether there is an association between oxidative stress and cellular proliferation. Higher levels of oxidative modifications in DNA and proteins were observed in carcinoma cells, but not in adenoma cells, than in the corresponding nontumorous epithelial cells by immunohistochemistry as well as high-performance liquid chromatography (HPLC)-based 8-OHdG determination. The fraction of proliferating cell nuclear antigen-positive cells was proportionally associated in adenocarcinomas with the staining intensities of 8-OHdG and 3-NT. Furthermore, Western blot analysis of the proteins extracted from carcinoma cells revealed several specific proteins modified by HNE or peroxynitrite. Thus we concluded that colorectal carcinoma, but not adenoma cells, are exposed to more oxidative stress than their corresponding nontumorous epithelial cells, regardless of clinical stage and histology, and further that the oxidative stress in carcinoma cells might stimulate cellular proliferation.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Adenoma; Adult; Aged; Aldehydes; Case-Control Studies; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Deoxyguanosine; Epithelial Cells; Female; Humans; Immunohistochemistry; Male; Middle Aged; Nitrates; Oxidants; Oxidative Stress; Reactive Oxygen Species; Time Factors

Deletions of loci on chromosomes 5q, 17p, 18q, and 22q, together with the incidence of p53 mutations and amplification of the double minute-2 gene were investigated in the sporadic colorectal tumors of 44 patients from a Spanish community. Chromosome deletions were analyzed by means of loss of heterozygosity analysis using a restriction fragment length polymorphism assay. Allelic losses were also detected by polymerase chain reaction (PCR)-single-stranded conformation polymorphism (SSCP) analysis of a polymorphic site in intron 2 of the p53 gene. The percentages of genetic deletions on the screened chromosomes were 39.3% (5q), 58.3% (17p), 40.9% (18q), and 40% (22q). Mutations in p53 exons 2-9 were examined by PCR-SSCP analysis and direct sequencing of the mutated region. Twenty of 44 tumor samples (45.45%) showed mutations at various exons except for exons 2, 3, and 9, the most frequent changes being G-->T transversion and C-->T transition. Because oxygen-free radicals play a role in the carcinogenesis process, we evaluated the oxidative status of the colorectal tumors. Antioxidant activities, lipid peroxidation, and DNA-damaged product concentrations in colon tumors and normal mucosa were compared. In tumor tissues, superoxide dismutase and catalase decreased fourfold and twofold, respectively, whereas glutathione peroxidase and reduced glutathione increased threefold. Malondialdehyde and 8-hydroxy-2-deoxyguanosine (8-OHdG) levels were twofold higher in colorectal tumors than in normal mucosa. Seven of 10 DNA tumor samples (70%) showing higher values of 8-OHdG also had genetic alterations at different chromosomal loci. In these samples, the p53 gene was deleted or mutated in 71.4% of cases. We concluded that the observed changes in the oxidative metabolism of the tumor cells and the consecutive increase in DNA damage may potentiate the genomic instability of different chromosomal regions, leading to further cell malignancy and tumor expansion.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Adult; Aged; Chromosomes, Human, Pair 1; Chromosomes, Human, Pair 18; Chromosomes, Human, Pair 22; Chromosomes, Human, Pair 5; Colorectal Neoplasms; Deoxyguanosine; DNA Mutational Analysis; DNA, Neoplasm; Female; Gene Amplification; Genes, p53; Genetic Markers; Glutathione; Heterozygote; Humans; Lipid Peroxides; Male; Middle Aged; Nuclear Proteins; Oxidation-Reduction; Polymorphism, Single-Stranded Conformational; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-mdm2; Sequence Deletion; Spain

We analyzed the level of 8-oxo-2'-deoxyguanosine in lymphocytes DNA of cancer patients undergoing radiotherapy. The results of this work indicate that exposure of cancer patients to therapeutic doses of ionizing radiation causes significant increase of the amount of 8-oxo-dG in DNA isolated from their lymphocytes.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Chromatography, High Pressure Liquid; Colorectal Neoplasms; Deoxyguanosine; DNA, Neoplasm; Dose-Response Relationship, Drug; Electrochemistry; Humans; Individuality; Lung Neoplasms; Lymphocytes; Male; Middle Aged; Spectrophotometry, Ultraviolet