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Tobacco smoking is a leading cause of death and disability. Interindividual variability in DNA adducts has been shown in subjects exposed to similar amounts of environmental carcinogens, including tobacco smoke. We have investigated the effects of smoking on DNA adducts in the nasal epithelium instead of peripheral blood in 42 volunteers, considering a panel of at-risk alleles by 32P-postlabeling and PCR. In detail, we have studied the association of DNA damage with tobacco smoke habits considering genes involved in DNA repair, including X-ray repair cross complementing protein 1 (XRCC1) Arg194Trp, XRCC protein 3 Thr241Met, and excision repair cross complementation group 2/xeroderma pigmentosum D (ERCC2/XPD) Lys751Gln polymorphisms. Then, we have analysed the combinations of the variant alleles of XRCC1 and ERCC2/XPD together with the wild type allele of XRCC3 by calculating the sum of at-risk alleles for lung cancer. DNA adducts were significantly higher in smokers with respect to nonsmokers (P < 0.001). An overall significant increase in adducts in heavy and long term smokers was found (P-values for trend <0.001, respectively). Multivariate regression analysis showed that adducts were linearly correlated to the number of cig per day (P < 0.001). Individuals with XRCC1 194Trp variant have a significant increment of DNA damage (P < 0.05), whereas XRCC3 241Met variant was inversely associated with adducts (P < 0.05). A null association was found with ERCC2/XPD. The levels of DNA adducts in participants with ≥4 at-risk alleles were two-fold increased with respect to those with one or fewer alleles (P < 0.01). A significant trend was observed (P-value for trend <0.05). Particularly, these results indicate a functional role for the XRCC1 and XRCC3 polymorphisms in genotoxic susceptibility related to the sensitivity to mutagens contained in tobacco smoke. Interindividual differences in at-risk alleles influence significantly the repair of damage in a tissue target of tobacco smoking-associated carcinogenesis. Our results support a functional role for the studied polymorphisms related to differences in cellular response to tobacco smoke mutagens. Phenotypes characterized by high levels of damage in susceptible individuals may be due to disorders in mechanisms designed to maintain cell homeostasis and DNA integrity. [ABSTRACT FROM AUTHOR]

Diet has been shown to modulate M1dG adduct, a biomarker of oxidative stress and lipid peroxidation. Thus, we analysed the association between diet and M1dG in 120 controls and 67 Map Ta Phut industrial estate workers in Rayong, Thailand, to evaluate the influence of fruit and vegetables, and fried and charcoal-grilled/barbecued food consumption on M1dG. M1dG was decreased in controls reporting to consume 14-17 servings/week of fruit and vegetables (mean ratio [MR]== 0.35, CI 0.18-0.69, p< 0.05). Conversely, a non-statistically significant M1dG increment was detected in controls consuming 9-18 servings/week of fried food (MR == 1.33, CI 0.88-2.00, p == 0.168). No effect of charcoal-grilled/barbecued food was found. No effect of diet was observed in workers. An association with smoking was observed in controls (MR == 1.88, CI 1.14-3.10, p < 0.05), but not in workers. M1dG can induce mutations and/or methylation changes within the promoter regions of cancer-related genes, thus promotion of healthy eating practices should be recommended. [ABSTRACT FROM AUTHOR]

Objectives. Little is known about the effects of exposure to petroleum refinery emissions on respiratory health in children. We evaluated lung function and markers of inflammation and oxidative stress in children and adolescents with and without asthma or wheezing symptoms living in a petrochemical polluted area (Sarroch, Sardinia) versus a reference area (Burcei). Methods. Parents of 275/300 6- to 14-year-old children living in Sarroch and parents of 214/323 children living in Burcei answered a questionnaire on respiratory symptoms and risk factors. Measurements of forced expiratory volume after 1 second (FEV1) and of forced expiratory flow rates at 25-75% of vital capacity (FEF25-75) were available in 27 and 23 asthma/wheezing-positive subjects and in 7 and 54 asthma/wheezing-negative subjects in Sarroch and in Burcei, respectively; for fractional exhaled nitric oxide (FENO) corresponding figures were 27 and 24 and 8 and 55 in Sarroch and in Burcei, respectively. Malondialdehyde-deoxyguanosine (MDA-dG) adduct levels in nasal mucosa were measured in 12- to 14-year-old adolescents (8 and 14 asthma/wheezing-positive and 20 and 28 asthma/wheezing-negative subjects in Sarroch and in Burcei, respectively). Air pollutants were assessed during 3 weeks, starting 1 week before lung function, FENO, and MDA-dG measurements. Generalized linear models were used to estimate the effect of the area of residence adjusting for confounders. Results. Weekly average concentrations of sulfur dioxide were 6.9-61.6μg/m3 in Sarroch versus 0.3-7.6μg/m3 in the rural area of Burcei; of nitrogen dioxide, 5.2-28.7μg/m3 versus 1.7-5.3μg/m3; and of benzene, 1.8-9.0μg/m3 versus 1.3-1.5μg/m3, respectively. Children living in Sarroch versus children living in the reference area showed an increase in wheezing symptoms {adjusted prevalence ratio=1.70 [90% confidence interval (CI)=1.01; 2.86]}; a decrease in lung function [variation in FEV1=−10.3% (90% CI=−15.0; −6.0%) and in FEF25-75=−12.9% (90% CI=−20.7; −4.3%)]; an increase in bronchial inflammation [variation in FENO=+35% (90% CI=11.7; 80.1%)]; and an increase in MDA-dG adducts of +83% (90% CI=22.9; 174.1%). Conclusions. Data from this small study are consistent with the role of environmental pollutants on lung function and inflammation. [ABSTRACT FROM AUTHOR]

We have conducted a randomized trial which investigated the ability of dietary changes (in particular diets rich in cruciferous vegetables and flavonoids), to increase urinary antimutagenicity and inhibit DNA damage in smokers. Ninety heavy smokers were recruited and randomly assigned to three groups, and were given three different diets. The first diet was based on flavonoid-rich foods, particularly cruciferous vegetables, but not based on supplementation; the second was a normal isocaloric diet (with an adequate administration of fruits and vegetables); and the third was based on supplementation of flavonoids in the form of green tea and soy products. DNA adducts were measured by 32P-postlabelling in exfoliated bladder cells at different times since the start of the trial. In spite of randomization, subjects in the control group smoked more than those in the experimental groups, and this can explain the higher adduct levels at baseline. A slight decrease in bulky DNA adducts in exfoliated bladder cells was observed after 1 year since the end in the supplementation group and after 1 month in white blood cells. The only statistically significant association was found in a regression model that adjusted for smoking, in which the increase in flavonoid intake was associated with a decrease in adducts after 1 year (P = 0.02). These data suggest that adherence to a diet rich in cruciferous vegetables and flavonoids might reduce genotoxicity in the human urinary bladder of smokers, but they should be interpreted with caution owing to small numbers and the uneven distribution of smoking habits in the experimental groups. Smoking is the most important single preventable cause of cancer; at the present stage of knowledge it is totally unlikely that certain dietary habits can seriously counteract the effects of tobacco smoking. [ABSTRACT FROM AUTHOR]

The aim was to assess the reliability of bulky DNA adducts measurement by means of the 32 P-post-labelling assay. The research design consisted of an intramethod reliability study. Buffy coats from 41 subjects were used to obtain two aliquots of 1–5 µg DNA for each subject; bulky DNA adducts were measured using the nuclease P1 32 P-post-labelling technique. The reliability of the measurement was assessed by means of the intraclass correlation coefficient (ICC), the distribution of the differences between the two measurements and the limits of agreement. The estimated ICC was 0.977, with a 95% confidence interval between 0.921 and 0.977. The limits of agreement were &PlusMinus;0.44 (DNA adducts per 10 8 nucleotides). Only three subjects had differences lying out of such limits. Bulky DNA adduct levels measured by the 32 P-post-labelling technique showed good reliability. Only one measurement is needed to use DNA adducts as a biomarker of exposure and, possibly, cancer risk. Besides, as a validation analysis, 32 P-post-labelling measurements can be repeated in only 20–30% of samples. [ABSTRACT FROM AUTHOR]

The recent introduction of biomarkers in population studies of lung cancer has improved the traditional epidemiological approach, especially in the detection of high risk groups. Many inhalable carcinogens form DNA adducts, an initial event in lung carcinogenesis, and therefore the identification of easily accessible sources of DNA for population studies is considered a leading priority in the field. In this study we compared the frequency of DNA adducts in samples from nasal brushing, bronchial biopsy and peripheral blood lymphocytes (PBL) in a group of 55 subjects, both smokers and non-smokers, undergoing bronchoscopy for diagnostic purposes. Polymorphisms in the CYP1A1, GSTM1 and GSTT1 genes were also evaluated. The level of DNA adducts measured by 32P-labelling assay in nasal mucosa (108 relative adduct level, mean SD 1.10 0.66) was higher than in bronchial mucosa (0.82 0.36) and in PBL (0.54 0.39, P < 0.01). DNA adducts measured in nasal mucosa and in PBL were correlated with those in bronchial mucosa (P < 0.01 and P < 0.05, respectively). DNA adducts in smokers were significantly increased in both nasal mucosa and PBL, with a significant doseresponse linear trend (P < 0.05). No significant effect on DNA adduction of the genetic polymorphisms investigated was found. Nasal mucosa brushing proved to be a suitable procedure for the 32P-labelling assay and its use in population studies should be further explored. [ABSTRACT FROM AUTHOR]

Frequent consumption of fresh fruit and vegetables, and polymorphisms in the detoxifying enzyme glutathione S-transferase M1 (GSTM1) and other metabolic genes have been shown to modulate cancer risk at some sites. We have shown recently that DNA adducts, a reliable indicator of genotoxic damage and, possibly, of cancer risk, are modulated by plasma levels of selected micronutrients. Here we further investigate the association between DNA adduct levels and consumption of major food groups and foods, and the estimated dietary intake of nutrients, taking into account the possible modifying effect of metabolic polymorphisms, in a larger sample of 634 healthy adults enrolled in a prospective study in Italy. DNA adducts and five polymorphic metabolic genotypes (GSTM1, GSTT1, NAT2, CYP1A1 and MTHFR) were determined in peripheral leukocytes by using 32P-postlabeling technique and PCR methods. DNA bulky adducts (mean: 7.82 0.40/109 nt) were detected in 482/634 samples (76.0%). Overall, DNA adduct levels were significantly and inversely associated with the intake of raw leafy vegetables (P = 0.02), non-citrus fruits (P = 0.04), potassium (P = 0.01) and -carotene (P = 0.05). No association was evident with the five genotypes. Stratification by GSTM1 genotype showed strong inverse associations of DNA adduct levels with increasing consumption of all vegetables combined (P = 0.04), leafy vegetables (P = 0.004), raw leafy vegetables (P = 0.002) and fish (P = 0.03) among 307 GSTM1-null subjects; strong inverse associations also emerged with estimated dietary intakes of -carotene (P = 0.004), vitamin E (P = 0.004), niacin (P = 0.02) and potassium (P = 0.01). In contrast, no association emerged among 295 subjects with a GSTM1-wild genotype. Overall, statistically significant interactions in predicting DNA adduct levels were observed between the GSTM1-null genotype and consumption of leafy vegetables (P = 0.01), white meat (P = 0.04), and intake of vitamin C (P = 0.04), vitamin E (P = 0.05) and -carotene (P = 0.02). Our results suggest that the role of a diet rich in antioxidants in preventing or reducing DNA adduct formation is restricted to subjects lacking the detoxifying activity of GSTM1 isoenzyme (~50% of the general population). [ABSTRACT FROM AUTHOR]

Ozone (O3), the major oxidant component in photochemical smog, mostly derives from photolysis of nitrogen dioxide. O3 may have biologic effects directly and/or via free radicals reacting with other primary pollutants and has been reported to influence daily mortality and to increase lung cancer risk. Although DNA damage may be caused by ozone itself, only other photochemical reaction products (as oxidised polycyclic aromatic hydrocarbons) may form bulky DNA adducts, a reliable biomarker of genotoxic damage and cancer risk, showing a seasonal trend. In a large series consisting of 320 residents in the metropolitan area of Florence, Italy, enrolled in a prospective study for the period 1993–1998 (206 randomly sampled volunteers, 114 traffic-exposed workers), we investigated the correlation between individual levels of DNA bulky adducts and a cumulative O3 exposure score. The average O3 concentrations were calculated for different time windows (0–5 to 0–90 days) prior to blood drawing for each participant, based on daily measurements provided by the local monitoring system. Significant correlations between DNA adduct levels and O3 cumulative exposure scores in the last 2–8 weeks before enrollment emerged in never smokers. Correlations were highest in the subgroup of never smokers residing in the urban area and not occupationally exposed to vehicle traffic pollution, with peak values for average concentrations 4–6 weeks before enrollment (r = 0.34). Our current findings indicate that DNA adduct formation may be modulated by individual characteristics and by the cumulative exposure to environmental levels of ozone in the last 4–6 weeks, possibly through ozone-associated reactive pollutants. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

DNA adducts, a reliable indicator of internal dose exposure to genotoxic agents and, possibly, of cancer risk, have been shown to be modulated by diet, particularly by the consumption of fresh fruit and vegetables, and by the intake of antioxidants (Palli et al., 2000, Int. J. Cancer, 87, 444-451). We have therefore investigated the association between DNA adducts in peripheral leukocytes and plasma levels of selected micronutrients, also taking into account the role of metabolic polymorphisms and smoking history, in a large independent random sample of volunteers enrolled in the prospective study EPIC-Italy (∼110 subjects from each of the three main geographical study areas, Northern, Central and Southern Italy). DNA adducts and five polymorphic metabolic genotypes were determined in peripheral leukocytes using the 32P-post-labelling technique and PCR methods. Plasma levels of six carotenoids, retinol and α- and γ-tocopherol were determined in the same blood sample. Among 331 subjects, 78.3% had detectable levels of DNA adducts (mean 7.46 ± 0.48 per 109 nucleotides). Vitamin supplementation was reported by only a few subjects (3.9%). Strong inverse associations emerged between levels of DNA adducts and plasma retinol (P = 0.02), α-tocopherol (P = 0.04) and γ-tocopherol (P = 0.03), but not carotenoids (except a borderline inverse association with β-carotene, P = 0.08). An inverse significant association with plasma levels of retinol and γ-tocopherol persisted in the subgroup of non-smokers, whereas a negative association with α-tocopherol emerged only in smokers. DNA adduct levels did not show any significant variation according to analyzed genotypes. Stratification by GSTM1 genotype, however, showed a significant negative association between DNA adduct levels and plasma levels of α- (P = 0.02) and β-carotene (P = 0.02) in subjects with the GSTM1 null genotype. Our results confirm that biomarkers of dietary intake of antioxidants significantly modulate DNA adducts and suggest specific inverse associations between DNA adduct levels and antioxidant concentrations among GSTM1 null subjects and smokers. [ABSTRACT FROM AUTHOR]

Industrial and urban workers may be exposed to significant levels of air pollutants resulting from the incomplete combustion of organic matter. The authors performed a meta-analysis of 13 DNA-adduct studies (32P-DNA postlabeling technique) on occupational cohorts exposed to air pollution. The association between levels of DNA adducts and air pollution exposure was significant both in heavily exposed industrial workers and in less severely exposed urban workers. Moreover, in an analysis using the seven studies that reported measuring levels of benzo[a]pyrene (B(a)P), a typical marker of exposure, DNA adduct levels in exposed workers (versus those in referents) were significantly correlated with air levels of B(a)P . The relation between DNA adducts and B(a)P was found to be linear at low doses and sublinear at high doses, indicating that DNA adduct formation tends to reach some kind of saturation point at higher levels of exposure to the chemical mixtures present in fumes. When the authors examined the efficiency of DNA adduct production associated with increasing air pollution exposures, the production of DNA adducts per unit of exposure was significantly decreased at higher B(a)P exposure levels. These findings suggest that linear downward extrapolations based on DNA adduct levels associated with B(a)P concentrations of ≥20 ng/m³ might be affected by underestimation bias. Am J Epidemiol 2001;153:546-58. [ABSTRACT FROM AUTHOR]

The `Mediterranean diet', a diet rich in cereals, fruit and vegetables, has been associated with lowering the risk of a variety of cancers of the digestive tract and the bladder. In a previous study, we showed that the high phenolic content these dietary components produce in the urine could be associated with higher antimutagenic properties of the urine and lower arylamine–DNA adducts in exfoliated bladder cells. We have conducted a case–control study on 162 bladder cancer patients and 104 hospital controls. Total aromatic DNA adducts were measured in white blood cells (WBC) of all subjects by 32P-post-labelling. Genetically based metabolic polymorphisms were analysed by PCR–RFLP (NAT2, GSTM1, GSTT1, GSTP1, COMT and NQO1). All subjects were interviewed about their tobacco use, dietary habits and other risk factors. The odds ratio (OR) for the risk of bladder cancer according to the presence/absence of WBC DNA adducts (detection limit 0.1 RAL×108) was 3.7 [95% confidence interval (CI) 2.2–6.3] and a dose–response relationship with levels of adducts was apparent. The association between case/control status and the presence of WBC DNA adducts was significantly stronger in the subjects who consumed fewer portions of fruit or vegetables per day (OR 7.80, 95% CI 3.0–20.30 for 0–1 portions of vegetables) than in the heavy consumers (OR 4.98 for consumers of 2 portions daily, OR 1.97 for consumers of 3 portions; similar but lower estimates were found for the intake of fruit). No association was noticed between tobacco smoking and WBC DNA adducts. Only NAT-2, among the several genotypes considered, was associated in a statistically significant way with the risk of bladder cancer (OR 1.72, 95% CI 1.03–2.87) and with the levels of WBC DNA adducts. Our report suggests that fruit and vegetables could protect against bladder cancer by inhibiting the formation of DNA adducts. [ABSTRACT FROM PUBLISHER]

Nasal epithelium is an easily accessible tissue that is potentially useful for human biomonitoring studies aimed at evaluating exposure to airborne carcinogens. We have devised a simple technique, which causes minimum distress to the informed patient, to obtain very small but sufficient biopsies from the inferior or middle turbinate head. DNA adducts were measured by 32P-postlabeling assay in nasal mucosa of nine cigarette smokers (including two subjects who had given up smoking shortly before sampling), two former smokers and 10 non-smoker healthy donors. None of the subjects reported other recent exposures to mutagens or carcinogens. Using the nuclease P1 technique, a mean adduct level of 4.8/10(8) bases and a specific spot pattern, the diagonal radioactive zone, were found in smokers, whereas non-smokers showed a significantly lower global level of DNA adducts, i.e. 1.4/10(8) bases, and no diagonal zone. Another important result was the presence of a significant association between DNA adduct level and the number of cigarettes smoked daily. These preliminary findings suggest that the level of DNA adducts measured from biopsies of the nasal mucosa is a reliable marker of exposure to cigarette smoking and uphold its use in biomonitoring exposures to other airborne DNA binding compounds. [ABSTRACT FROM PUBLISHER]

Simple Summary: Metastatic colorectal cancer (mCRC) has high incidence and mortality. Nevertheless, innovative biomarkers have been developed for predicting the response to therapy. We have examined the ability of learning methods to build prognostic and predictive models to predict response to chemotherapy, alone or combined with targeted therapy in mCRC patients, by targeting specific narrative publications. After a literature search, 26 original articles met inclusion and exclusion criteria and were included in the study. We showed that all investigations conducted in this field provided generally promising results in predicting the response to therapy or toxic side-effects, using a meta-analytic approach. We found that radiomics and molecular biomarker signatures were able to discriminate response vs. non-response by correctly identifying up to 99% of mCRC patients who were responders and up to 100% of patients who were non-responders. Our study supports the use of computer science for developing personalized treatment decision processes for mCRC patients. Tailored treatments for metastatic colorectal cancer (mCRC) have not yet completely evolved due to the variety in response to drugs. Therefore, artificial intelligence has been recently used to develop prognostic and predictive models of treatment response (either activity/efficacy or toxicity) to aid in clinical decision making. In this systematic review, we have examined the ability of learning methods to predict response to chemotherapy alone or combined with targeted therapy in mCRC patients by targeting specific narrative publications in Medline up to April 2022 to identify appropriate original scientific articles. After the literature search, 26 original articles met inclusion and exclusion criteria and were included in the study. Our results show that all investigations conducted on this field have provided generally promising results in predicting the response to therapy or toxic side-effects. By a meta-analytic approach we found that the overall weighted means of the area under the receiver operating characteristic (ROC) curve (AUC) were 0.90, 95% C.I. 0.80–0.95 and 0.83, 95% C.I. 0.74–0.89 in training and validation sets, respectively, indicating a good classification performance in discriminating response vs. non-response. The calculation of overall HR indicates that learning models have strong ability to predict improved survival. Lastly, the delta-radiomics and the 74 gene signatures were able to discriminate response vs. non-response by correctly identifying up to 99% of mCRC patients who were responders and up to 100% of patients who were non-responders. Specifically, when we evaluated the predictive models with tests reaching 80% sensitivity (SE) and 90% specificity (SP), the delta radiomics showed an SE of 99% and an SP of 94% in the training set and an SE of 85% and SP of 92 in the test set, whereas for the 74 gene signatures the SE was 97.6% and the SP 100% in the training set. [ABSTRACT FROM AUTHOR]

Molecular mechanisms underlying Hepatitis C virus (HCV)-associated hepatocellular carcinoma (HCC) pathogenesis are still unclear. Therefore, we analyzed the levels of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and other oxidative lesions at codon 176 of the p53 gene, as well as the generation of 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3H)-one deoxyguanosine (M1dG), in a cohort of HCV-related HCC patients from Italy. Detection of 8-oxodG and 5-hydroxycytosine (5-OHC) was performed by ligation mediated-polymerase chain reaction assay, whereas the levels of M1dG were measured by chromatography and mass-spectrometry. Results indicated a significant 130% excess of 8-oxodG at –TGC– position of p53 codon 176 in HCV-HCC cases as compared to controls, after correction for age and gender, whereas a not significant increment of 5-OHC at –TGC– position was found. Then, regression models showed an 87% significant excess of M1dG in HCV-HCC cases relative to controls. Our study provides evidence that increased adduct binding does not occur randomly on the sequence of the p53 gene but at specific sequence context in HCV-HCC patients. By-products of lipid peroxidation could also yield a role in HCV-HCC development. Results emphasize the importance of active oxygen species in inducing nucleotide lesions at a p53 mutational hotspot in HCV-HCC patients living in geographical areas without dietary exposure to aflatoxin B1. [ABSTRACT FROM AUTHOR]

Asbestos fibers include a group of silicate minerals that occur in the environment and are widely employed in occupational settings. Asbestos exposure has been associated to various chronic diseases; such as pulmonary fibrosis; mesothelioma; and lung cancer; often characterized by a long period of latency. Underlying mechanisms that are behind the carcinogenic effect of asbestos have not been fully clarified. Therefore; we have conducted an epidemiological study to evaluate the relationship between 8-hydroxy-2′-deoxyguanosine (8-oxodG), one of the most reliable biomarkers of oxidative stress and oxidative DNA damage; and asbestos exposure in the peripheral blood of residents in Tuscany and Liguria regions; Italy; stratified by occupational exposure to this carcinogen. Levels of 8-oxodG were expressed such as relative adduct labeling (RAL); the frequency of 8-oxodG per 105 deoxyguanosine was significantly higher among exposed workers with respect to the controls; i.e., 3.0 ± 0.2 Standard Error (SE) in asbestos workers versus a value of 1.3 ± 0.1 (SE) in unexposed controls (p < 0.001). When the relationship with occupational history was investigated; significant higher levels of 8-oxodG were measured in current and former asbestos workers vs. healthy controls; 3.1 ± 0.3 (SE) and 2.9 ± 0.2 (SE), respectively. After stratification for occupational history; a significant 194% excess of adducts was found in workers with 10 or more years of past asbestos exposure (p < 0.001). 8-oxodG can be used for medical surveillance programs of cohorts of workers with past and recent exposures to carcinogens for the identification of subjects requiring a more intense clinical surveillance. [ABSTRACT FROM AUTHOR]