DNA Damage In Cancer Patients Research Articles

Vitamin D level and endogenous DNA damage in patients with cancers in Duhok city, KRG-Iraq

IntroductionMany clinical and pre-clinical studies suggested the protective effect of vitamin D against cancer development and cancer progression. Vitamin D deficiency is highly prevalent worldwide, and its link to DNA damage is worthy to study. It has been shown that vitamin D supplementation can reduce the risk of cancer with a favorable prognosis. Studies on DNA damage in different types of cancer and its link to plasma vitamin D has not been found in literature. Patients and methodsIn this study we included 45 patients with different types of cancers and 35 healthy individuals as controls. The plasma vitamin D levels were measured in all participants. DNA damage levels of peripheral blood (mononuclear) cells in 45 newly diagnosed and untreated cancer patients and in 35 healthy individuals were measured using Alkaline Comet Assay technique. ResultsThe DNA damage observed in cancer patients was significantly higher than in healthy individuals. Interestingly, we have found a significant inverse correlation between the plasma levels of vitamin D and DNA damage in cancer patients (p < 0.0001) and in healthy individuals (p < 0.001). ConclusionThere is an inverse association between endogenous DNA damage and plasma vitamin D levels. Patients with vitamin D deficiency show highest levels of DNA damage suggesting that deficiency of vitamin D is probably one of the factors which increases the risk of cancer.

Stochastic microsensors for the assessment of DNA damage in cancer

Three stochastic microsensors based on graphite powder modified with three different oleamides: N-(2-piperidin-1-ylethyl)oleamide, N-(3,4-dihydroxyphenethyl)oleamide and N-(2-morpholinoethyl)oleamide, were designed, characterized, and used to assess DNA damage in cancer by assaying two biomarkers namely 8-nitroguanine and 8-hydroxy-2′-deoxyguanosine. The two biomarkers were determined from urine and whole blood samples. The characterization of the microsensors was done at two pHs 7.40 and 3.00. The best microsensor for the simultaneous determination of biomarkers in whole blood and urine samples was the one based on the graphite paste modified with N-(3,4-dihydroxyphenethyl)oleamide. The results indicated that the proposed microsensors can be reliably used for pattern recognition and quantitative determination of 8-nitroguanine and 8-hydroxy-2′-deoxyguanosine in whole blood and urine, and accordingly, for the assessment of DNA damage in cancer patients.

Oxidative DNA damage in cancer patients: Associations between persistent organic pollutants and biomarkers of cellular targets

Oxidative DNA damage in cancer patients: Associations between persistent organic pollutants and biomarkers of cellular targets

DNA damage in peripheral blood leukocytes in tobacco users.

Aim:To Quantify the DNA single-stranded breaks in the peripheral blood leukocytes (PBLs) of tobacco-habituated individuals with clinically normal mucosa and patients with oral carcinoma.Objectives:To evaluate DNA damage levels in PBLs of tobacco-habituated individuals with clinically normal mucosa and patients with oral carcinoma and compare with a control group of healthy volunteers. To evaluate the extent of DNA damage in PBLs using Single Cell Gel Electrophoresis (SCGE) in the above groups.Materials and Methods:Patients who were attending the outpatient department were enrolled in this study. A control group of 30 healthy volunteers included in Group I were selected from various age groups who are not tobacco users in any form. Thirty patients with tobacco habituation but with clinically normal mucosa were included in Group II, while 30 tobacco-habituated patients with oral squamous carcinoma were included in Group III. A biopsy was taken from the representative area and confirmed histologically. Intravenous blood samples were collected from all the groups for evaluation of the extent of DNA damage using ethidium bromide-stained slides under fluorescent microscope. The DNA tail length was calculated by subtracting the diameter from the total length. Twenty-five randomly selected cells per slide were analyzed and mean calculated.Results:The mean DNA damage levels in patients with tobacco habits were compared with that of the control group and the results were found to be statistically significant. The mean DNA damage level in PBLs between tobacco-habituated patients with normal mucosa and oral cancer patients was found to be statistically significant. The DNA damage in cancer patients was compared with the control group and the results were found to be statistically significant.Conclusion:DNA damage evaluation in PBLs by SCGE technique is a sensitive and reliable indicator of tobacco insult.

Alkaline comet assay study with breast cancer patients: evaluation of baseline and chemotherapy-induced DNA damage in non-target cells

The sensitivity of the alkaline comet assay for the evaluation of baseline and treatment-induced DNA damage in white blood cells of breast cancer patients receiving adjuvant chemotherapy according to three conventional anthracycline- and cyclophosphamide-containing protocols was investigated. Additionally, baseline DNA damage in cancer patients was compared with the levels of DNA damage recorded in healthy women. Altogether 30 patients with diagnosed breast cancer and 30 female blood donors with no known familial history of breast cancer participated in the study. Alkaline comet assay was performed according to standard protocol and DNA migration in peripheral blood leukocytes was measured by a computer-based image analysis system. For each subject the frequency of "damaged" cells, i.e., long-tailed nuclei (LTN) with tail length exceeding 95th percentile for the considered parameter among controls, is also reported. Breast cancer patients had significantly increased background levels of DNA damage in their peripheral blood leukocytes as compared to healthy women. Prior to the chemotherapy, a majority of patients showed a statistically significant increase in the number of LTN compared to healthy blood donors. Marked interindividual variations in baseline DNA damage among patients were recorded, some of them related to the disease stage and status. The present study confirmed the alkaline comet assay as a sensitive technique able to detect significantly elevated DNA migration in blood cells of patients already one hour after completion of the first cycle of chemotherapy. Administration of antineoplastic drugs in three chemotherapy protocols studied induced a similar increase of primary DNA damage in nontarget cells. The evaluation of the LTN frequencies indicates the best response to the protocol containing cyclophosphamide, methotrexate and 5-fluorouracil (CMF). Our results point to the significance of simultaneous evaluation of DNA migration and frequency of LTN in the same subject and approved the use of alkaline comet assay as a suitable method for the routine detection of critical DNA lesions produced after administration of antineoplastic drugs in the clinical settings.

Determination of urinary 8-hydroxy-2′-deoxyguanosine by two approaches—capillary electrophoresis and GC/MS: An assay for in vivo oxidative DNA damage in cancer patients

8-Hydroxy-2'-deoxyguanosine (8OHdG) has been considered as an excellent marker of oxidative DNA damage associated with age-related diseases such as cancer. In this paper, two sensitive methods-capillary electrophoresis with electrochemical detection (CE-ECD) and gas chromatography/mass spectrometry (GC/MS) were developed for urinary 8OHdG analysis. The R.S.D. of the spiked recovery of the two methods for determining urinary 8OHdG was 4.03% and 8.25%, respectively, and the results from the two methods have a good consistency (r=0.999, P<0.01). The developed CE-ECD method was applied to investigate the urinary 8OHdG levels in different cancer patients and follow up the response of therapy. It was found that the excretion levels of urinary 8OHdG in cancer patients were significantly higher than those in healthy persons (35.26+/-27.96 nM versus 13.51+/-5.08 nM, P<0.05), and cancer patients receiving surgical therapy and chemotherapy showed a significant decrease in urinary 8OHdG.

Immunochemical detection of oxidative DNA damage in cancer and aging using anti-reactive oxygen species modified DNA monoclonal antibody

The formation of reactive oxygen species (ROS), although a normal cellular activity, is considerably enhanced under chronic inflammatory conditions and ischemia. These species have been implicated in various disorders, mutagenesis, carcinogenesis and aging. Of many macromolecules, DNA is the most susceptible to hydroxyl radical, the most reactive of the ROS. The present study is designed to detect oxidative DNA damage in cancer patients and healthy aged humans using an anti-ROS-DNA monoclonal antibody (mAb). Purified calf thymus DNA fragments (approximate size 400 bp) were modified with ·OH, generated by UV-irradiation (254 nm) of hydrogen peroxide. ROS-modified DNA was characterized by UV-spectroscopy, melting temperature, alkaline sucrose density gradient ultracentrifugation and ion-exchange chromatography. ROS-DNA showed single strand breaks, decrease in T m, modification of thymine (58.3%) and guanine (20%). The mAb generated against ROS-DNA was characterized for antigen binding specificity by competition ELISA. Monoclonal antibody showed strong binding to ROS-modified DNA, its modified fragments, polynucleotides and bases. With the exception of native DNA, binding of unmodified polynucleotides and bases was much lower. The mAb distinctly recognized DNA samples from lymphocytes of healthy aged humans and gave maximum inhibitions of 49, 53, 64 and 70%, while not reacting with DNA from young population. Similarly, oxidative lesions in DNA from cancer patients were also efficiently recognized by the mAb. DNA from healthy controls served as negative control. The studies demonstrate that the mAb, although cross-reactive, preferentially binds ROS-modified epitopes on DNA. High reactivity of mAb to DNA samples from cancer patients and healthy aged humans indicates increased oxidative stress leading to DNA damage.

Variability in DNA repair and individual susceptibility to genotoxins

DNA repair is an important mechanism of cellular protection from the effects of genotoxic chemicals. Although extensive evidence from studies in experimental systems indicates that variation in DNA repair can significantly influence susceptibility to genotoxins, corresponding studies in human populations are so far limited, mainly because of methodological difficulties. One system, using observations of the accumulation and repair of DNA damage in cancer patients treated with alkylating cytostatic drugs, has provided useful information for assessing the effects of interindividual variation in DNA repair activity on the induction of genotoxic effects in humans. The most detailed studies of this kind have been carried out on patients with cancer (i.e., Hodgkin disease, malignant melanoma) treated with the methylating cytostatic drugs procarbazine or dacarbazine; these studies have provided detailed information on dose-response relationships. They have also demonstrated the protective role of the repair enzyme O6-alkylguanine-DNA alkyltransferase against the accumulation of the premutagenic methylated DNA lesion O6-methylguanine in patients' DNA. Given the strong evidence that exposure of the general population to environmental methylating agents may be extensive, as indicated by the frequent discovery of methylated DNA adducts in human DNA, data on DNA damage and repair in alkylating drug-treated patients and their modulation by host factors may prove useful in efforts to assess the possible carcinogenic risks posed by exposure to environmental methylating agents.

Determination of urinary 8-hydroxydeoxyguanosine by automated coupled-column high performance liquid chromatography: a powerful technique for assaying in vivo oxidative DNA damage in cancer patients

An automated analytical method has been developed for determination of the oxidative DNA adduct, 8-hydroxydeoxyguanosine (8OHdG) in human urine, based on coupled-column high performance liquid chromatography with electrochemical detection. Urine is concentrated on Bondelut CH by means of an automated sample processor, and the enriched sample injected on to a polymeric reversed phase column coupled in line with an electrochemical detector and a C 18 reversed phase column. By use of the electrochemical detector, a suitable retention time interval is set for collection of the fraction containing 8OHdG from the chromatography on the first column; this fraction is collected in a 2 mL loop and injected onto the C 18 column. The system is operated by an automatic valve station controlled by an integrator. The method has a large sample capacity and measures 31.1, 15.7, and 7.43 nmol 8OHdG/L urine with variation coefficients of 8, 8 and 24% within series and 8, 11 and 23% between series. Normal healthy individuals were found to excrete 14.9 ± 7.8 nmol 8OHdG/24 h, or 1.11 ± 0.62 μmol 8OHdG per mol creatinine, in their urine, whereas increased levels of 8OHdG were found in 24 h collections from a variety of cancer patients, both in samples taken before onset of oncological therapy (1.84 ± 1.12 μmol/mol creatinine, P < 0.01 versus healthy individuals) and after therapy onset (2.18 ± 1.44 μmol/mol creatinine, P < 0.001 versus healthy individuals). Moreover, mean values of 8OHdG in random urinary samples from cancer patients were significantly higher than from healthy individuals (2.42 ± 2.28 versus 1.19 ± 0.48 μmol/mol creatinine, P < 0.001), both in samples taken before therapy onset (1.91 ± 0.96, P < 0.001 versus healthy individuals) and after (2.57 ± 2.46, P < 0.001 versus healthy individuals). High levels of urinary 8OHdG were found in patients subjected to whole body irradiation, and in patients receiving chemotherapy with various cytostatic agents. The potential use of the method for detecting increased urinary 8OHdG excretion and conditions associated with increased oxidative DNA damage in humans is discussed.