• LC-QTOF/MS metabolomic profiles in human plasma after a 5-week high dietary fiber intake.

      Johansson-Persson, Anna; Barri, Thaer; Ulmius, Matilda; Onning, Gunilla; Dragsted, Lars Ove (2013-05)
      The objective was to investigate the alterations of plasma metabolome profiles to identify exposure and effect markers of dietary fiber intake. Subjects (n = 25) aged 58.6 (1.1) years (mean and SD) with a body mass index of 26.6 (0.5) kg/m(2) were given a high fiber (HF) and a low fiber (LF) diet, in a 5-week randomized controlled crossover intervention. The HF diet consisted of oat bran, rye bran, and sugar beet fiber incorporated into test food products, whereas the LF diet was made of equivalent food products to the HF diet, but without adding fibers. Blood plasma samples were collected at the start and end of each intervention period and analyzed by LC-QTOF/MS. In total, 6 features in positive mode and 14 features in negative mode were significantly different between the HF and the LF diet (p < 0.01, q < 0.05). Two markers, 2,6-dihydroxybenzoic acid and 2-aminophenol sulfate, were increased after HF diet, along with a tentatively identified saponin derived from oat avenacosides. The untargeted metabolomics approach enabled the identification of two new markers of dietary fiber intake in human plasma. Further studies will be needed to verify if these markers could serve as compliance markers of fiber intake.
    • Lipid peroxidation-induced DNA damage in cancer-prone inflammatory diseases: a review of published adduct types and levels in humans.

      Nair, Urmila; Bartsch, Helmut; Nair, Jagadeesan (2007-10-15)
      Persistent oxidative stress and excess lipid peroxidation (LPO), induced by inflammatory processes, impaired metal storage, and/or dietary imbalance, cause accumulations and massive DNA damage. This massive DNA damage, along with deregulation of cell homeostasis, leads to malignant diseases. Reactive aldehydes produced by LPO, such as 4-hydroxy-2-nonenal, malondialdehyde, acrolein, and crotonaldehyde, react directly with DNA bases or generate bifunctional intermediates which form exocyclic DNA adducts. Modification of DNA bases by these electrophiles, yielding promutagenic exocyclic adducts, is thought to contribute to the mutagenic and carcinogenic effects associated with oxidative stress-induced LPO. Ultrasensitive detection methods have facilitated studies of the concentrations of promutagenic DNA adducts in human tissues, white blood cells, and urine, where they are excreted as modified nucleosides and bases. Thus, immunoaffinity-(32)P-postlabeling, high-performance liquid chromatography-electrochemical detection, gas chromatography-mass spectrometry, liquid chromatography-tandem mass spectrometry, immunoslotblot assay, and immunohistochemistry have made it possible to detect background concentrations of adducts arising from endogenous LPO products in vivo and studies of their role in carcinogenesis. These background adduct levels in asymptomatic human tissues occur in the order of 1 adduct/10(8) and in organs affected by cancer-prone inflammatory diseases these can be 1 or 2 orders of magnitude higher. In this review, we critically discuss the accuracy of the available methods and their validation and summarize studies in which measurement of exocyclic adducts suggested new mechanisms of cancer causation, providing potential biomarkers for cancer risk assessment in humans with cancer-prone diseases.
    • Lung cancer risk associated with selenium status is modified in smoking individuals by Sep15 polymorphism.

      Jablonska, Ewa; Gromadzinska, Jolanta; Sobala, Wojciech; Reszka, Edyta; Wasowicz, Wojciech (2008-02)
      BACKGROUND: Selenium (Se) is a trace element suggested to act chemopreventive in lung cancer. The mechanism by which Se suppresses tumour development may be associated with some of the functions of selenoproteins, including 15 kDa selenoprotein (Sep15). This protein exhibits antioxidant properties and thus may be involved in the process of carcinogenesis. Recently, it has been shown that the genetic polymorphism of Sep15, resulting in different response of the protein to Se, is associated with the risk of breast and head and neck cancers. AIM OF THE STUDY: The aim of the study was to investigate the possible association between lung cancer risk and Sep15 polymorphism in combination with Se status in the Polish population. METHODS: The study concerned 325 cases and 287 controls. All the participants were smokers. Plasma Se concentration was determined using graphite furnace atomic absorption spectrometry, and Sep15 polymorphism (1125 G/A transition within 3'-untranslated region) was detected with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. RESULTS: The adjusted odds ratios (ORs) for lung cancer cases, compared to individuals with Sep15 wild type variant (GG), were: 0.91 (95% CI: 0.64-1.32) for the heterozygous variant (GA) and 0.80 (95% CI: 0.39-1.65) for the homozygous variant (AA). Although plasma Se concentration was statistically lower in lung cancer cases (49.4 +/- 17.4 ng/ml) compared to controls (53.3 +/- 14.0 ng/ml, p < 0.002), the analysis of the joint effect of Sep15 polymorphism and Se status for lung cancer development revealed that lung cancer risk differed between the Se15 genotype groups. An increasing Se concentration was associated with a decreased risk in all individuals; however, at Se concentration above 80 ng/ml, the risk started to increase in individuals possessing the Sep15 1125 GG or GA genotype. CONCLUSIONS: It appears that among smoking individuals, those with the Sep15 1125 AA genotype may benefit most from a higher Se intake, whereas in those with the GG or GA genotype, a higher Se status may increase the risk for lung cancer.
    • Lung cancers attributable to environmental tobacco smoke and air pollution in non-smokers in different European countries: a prospective study.

      Vineis, Paolo; Hoek, Gerard; Krzyzanowski, Michal; Vigna-Taglianti, Federica; Veglia, Fabrizio; Airoldi, Luisa; Overvad, Kim; Raaschou-Nielsen, Ole; Clavel-Chapelon, Francoise; Linseisen, Jacob; et al. (2007)
      BACKGROUND: Several countries are discussing new legislation on the ban of smoking in public places, and on the acceptable levels of traffic-related air pollutants. It is therefore useful to estimate the burden of disease associated with indoor and outdoor air pollution. METHODS: We have estimated exposure to Environmental Tobacco Smoke (ETS) and to air pollution in never smokers and ex-smokers in a large prospective study in 10 European countries (European Prospective Investigation into Cancer and Nutrition)(N = 520,000). We report estimates of the proportion of lung cancers attributable to ETS and air pollution in this population. RESULTS: The proportion of lung cancers in never- and ex-smokers attributable to ETS was estimated as between 16 and 24%, mainly due to the contribution of work-related exposure. We have also estimated that 5-7% of lung cancers in European never smokers and ex-smokers are attributable to high levels of air pollution, as expressed by NO2 or proximity to heavy traffic roads. NO2 is the expression of a mixture of combustion (traffic-related) particles and gases, and is also related to power plants and waste incinerator emissions. DISCUSSION: We have estimated risks of lung cancer attributable to ETS and traffic-related air pollution in a large prospective study in Europe. Information bias can be ruled out due to the prospective design, and we have thoroughly controlled for potential confounders, including restriction to never smokers and long-term ex-smokers. Concerning traffic-related air pollution, the thresholds for indicators of exposure we have used are rather strict, i.e. they correspond to the high levels of exposure that characterize mainly Southern European countries (levels of NO2 in Denmark and Sweden are closer to 10-20 ug/m3, whereas levels in Italy are around 30 or 40, or higher).Therefore, further reduction in exposure levels below 30 ug/m3 would correspond to additional lung cancer cases prevented, and our estimate of 5-7% is likely to be an underestimate. Overall, our prospective study draws attention to the need for strict legislation concerning the quality of air in Europe.
    • Lymphoma; Pre-diagnostic Blood Markers and Occupational and Environmental Exposures.

      Saberi Hosnijeh, Fatemeh (Utrecht University, 2012, 2012)
      The overall aim of this thesis is to study the possible perturbations of the immune system by occupational and environmental risk factors of Non-Hodgkin lymphoma (NHL) and to study these changes in relation to NHL risk in prospective cohorts. In the first section, we validated the application of single blood cytokine measurements as a biomarker of immune status in prospective epidemiological studies. Potential utility of stored blood samples of a prospective cohort was evaluated by the effect of different blood sample types and freeze-thaw cycles on cytokine levels. This study showed strong correlations between different sample types. Moreover, freeze-thaw cycles did not markedly change cytokine levels. The intra-individual variance in cytokine levels was much smaller than the inter-individual variance which supports the notion that a single cytokine measurement can be used to characterize an individual's immune profile prospectively. Subsequently, we assessed the levels of these cytokines in pre-diagnostic blood samples of participants of a case–control study nested into the Italian European Prospective Investigation into Cancer and Nutrition cohort (EPIC) and determined their association with the risk of developing NHL. The results suggest a possible association between increased/decreased plasma levels of interleukin (IL)2, inter-cellular adhesion molecule, interferon gamma (IFN-γ), and tumor necrosis factor alpha with NHL risk. In the second section, we studied the possible immunological effects of two possibly lymphomagens: an occupational exposure (i.e. 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD)) and an environmental risk factor (i.e. obesity). We assessed a broad range of immunologic parameters directed towards detecting abnormalities in the humoral and cellular arms of the immune system among workers exposed to chlorophenoxy herbicides, chlorophenols and dioxins in particular TCDD. These studies showed that plasma TCDD levels were not associated with markers of humoral immunity with the possible exception of a decrease in complement factor 4 levels. Most lymphocyte subsets, in particular the B cell compartment, showed a decrease in cell counts with increasing levels of TCDD. Moreover, blood levels of most cytokines, chemokines and growth factors had a negative association with TCDD levels with a formal statistical significance for fractalkine, transforming growth factor alpha and fibroblast growth factor 2. These changes were independent from the changes in blood cell counts. Our findings support the notion that dioxin exposure can have an adverse impact on the immune system and likely suppresses the immune system. To identify immunologic hallmarks of obesity, we measured plasma levels of cytokines in pre-diagnostic blood samples of participants of a case-control study nested in the Italian EPIC cohort. IL8, IL10, IFN-γ, and interferon-induced protein 10 (IP10) were related to obesity. However, the set of obesity predictors (IL8, IL10, IFN-γ, IP10) were not associated with future NHL risk. Our studies support that subtle perturbations in the immune system may precede lymphoma development and suggest that B cell activation, chronic inflammation and/or an unbalance in Th1/Th2-responses are likely important phenomena in lymphomagenesis. Although, possible occupational and environmental risk factors of NHL influence the immune system they did not pertubate immune markers shown to be associated with future NHL risk.
    • Measurement and meaning of oxidatively modified DNA lesions in urine.

      Cooke, Marcus S.; Olinski, Ryszard; Loft, Steffen (2008-01)
      BACKGROUND: Oxidatively generated damage to DNA has been implicated in the pathogenesis of a wide variety of diseases. The noninvasive assessment of such damage, i.e., in urine, and application to large-scale human studies are vital to understanding this role and devising intervention strategies. METHODS: We have reviewed the literature to establish the status quo with regard to the methods and meaning of measuring DNA oxidation products in urine. RESULTS: Most of the literature focus upon 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), and whereas a large number of these reports concern clinical conditions, there remains (a) lack of consensus between methods, (b) possible contribution from diet and/or cell death, (c) no definitive DNA repair source of urinary 2'-deoxyribonucleoside lesions, and (d) no reference ranges for healthy or diseased individuals. CONCLUSIONS: The origin of 8-oxodG is not identified; however, recent cell culture studies suggest that the action of Nudix hydrolase(s) on oxidative modification of the nucleotide pool is a likely candidate for the 8-oxodG found in urine and, potentially, of other oxidized 2'-deoxyribonucleoside lesions. Literature reports suggest that diet and cell death have minimal, if any, influence upon urinary levels of 8-oxodG and 8-oxo-7,8-dihydroguanine, although this should be assessed on a lesion-by-lesion basis. Broadly speaking, there is consensus between chromatographic techniques; however, ELISA approaches continue to overestimate 8-oxodG levels and is not sufficiently specific for accurate quantification. With increasing numbers of lesions being studied, it is vital that these fundamental issues are addressed. We report the formation of the European Standards Committee on Urinary (DNA) Lesion Analysis whose primary goal is to achieve consensus between methods and establish reference ranges in health and disease.
    • Mechanisms of combined action of different chemopreventive dietary compounds: a review.

      de Kok, Theo M.; van Breda, Simone G.; Manson, Margaret M. (2008-05)
      Consumption of fruits and vegetables has generally been associated with a decrease in cancer incidence and cardiovascular disease. Over the years, numerous bioactive compounds have been identified that contribute to these beneficial health effects. More recently, evidence is emerging that specific combinations of phytochemicals may be far more effective in protecting against cancer than isolated compounds. Combinatorial effects have been observed where any one of the single agents is inactive. Apart from interactions among dietary micronutrients, drug-phytochemical interactions have also been observed, indicating possibilities for improved cancer therapeutic strategies. Our understanding of the molecular mechanisms underlying such synergistic effects is still limited, but it appears that different combinations of complementary modes of actions are involved. In this review, we discuss the molecular mechanisms that are likely to be involved in cancer chemoprevention and summarize the most important findings of those studies that report synergistic chemopreventive effects of dietary compounds.
    • Mechanisms related to the genotoxicity of particles in the subway and from other sources.

      Karlsson, Hanna L.; Holgersson, Asa; Moller, Lennart (2008-03)
      Negative health effects of airborne particles have clearly been shown in epidemiological studies. People get exposed to particles from various sources such as the combustion of, for example, diesel and wood and also from particles arising from tire-road wear. Another source of importance for certain populations is exposure to particles in subway systems. We recently reported that these particles were more genotoxic when compared to that of several other particle types. The aim of this study was to further investigate and compare the toxicity of subway particles and particles from other sources as well as investigate some mechanisms behind the genotoxicity of subway particles. This was done by comparing the ability of subway particles and particles from a street, pure tire-road wear particles, and particles from wood and diesel combustion to cause mitochondrial depolarization and to form intracellular reactive oxygen species (ROS). Furthermore, the genotoxicity and ability to cause oxidative stress was compared to magnetite particles since this is a main component in subway particles. It was concluded that the subway particles and also street particles and particles from wood and diesel combustion caused mitochondrial depolarization. The ability to damage the mitochondria is thus not the only explanation for the high genotoxicity of subway particles. Subway particles also formed intracellular ROS. This effect may be part of the explanation as to why subway particles show such high genotoxicity when compared to that of other particles. Genotoxicity can, however, not be explained by the main component, magnetite, by water-soluble metals, or by intracellular mobilized iron. The genotoxicity is most likely caused by highly reactive surfaces giving rise to oxidative stress.
    • Melphalan-induced DNA damage in vitro as a predictor for clinical outcome in multiple myeloma.

      Dimopoulos, Meletios A.; Souliotis, Vassilis L.; Anagnostopoulos, Athanasios; Bamia, Christina; Pouli, Anastasia; Baltadakis, Ioannis; Terpos, Evangelos; Kyrtopoulos, Soterios A.; Sfikakis, Petros P. (2007-11)
      BACKGROUND AND OBJECTIVES: As new therapeutic options for multiple myeloma (MM) emerge, identification of biological markers which could predict clinical response to standard treatment with high-dose melphalan (HDM) supported by autologous stem cell transplantation (ASCT) becomes more important. DESIGN AND METHODS: Melphalan-induced damage formation and repair of monoadducts and interstrand cross-links in the p53 gene were studied in peripheral blood mononuclear cells obtained from 32 patients prior to therapy. The same studies were performed in the peripheral blood cells of these patients immediately after subsequent HDM administration. Clinical response and time to progression were correlated with molecular endpoints obtained in vitro. RESULTS: Values for all molecular end-points examined in vitro were highly correlated with the respective in vivo results within individual patients. All in vitro end-points indicative of increased DNA damage and slower repair capacity were predictive of a favorable response to HDM; the area under the curve of total adducts (AUC-TA) had the highest predictive ability. Using the cut-off value of 736 adducts/10(6) nucleotides x h for the AUC-TA, the positive predictive value for clinical response to HDM was 100%. Moreover, patients with an AUC-TA equal to or higher than this cut-off value had significantly longer times to progression than had patients with an AUC-TA lower than the cut-off value (hazard ratio 0.19; 95% confidence intervals 0.06 to 0.60). INTERPRETATION AND CONCLUSIONS: An in vitro assay to quantify melphalan-induced p53-specific damage formation/repair can be used to select those patients with MM who are more likely to benefit from HDM supported by ASCT.
    • Mendelian randomization.

      Brennan, Paul; Hung, Rayjean (Nofer Institute of Occupational Medicine, 2008)
    • Meta- and pooled analyses of the cytochrome P-450 1B1 Val432Leu polymorphism and breast cancer: a HuGE-GSEC review.

      Paracchini, Valentina; Raimondi, Sara; Gram, Inger T.; Kang, Daehee; Kocabas, Neslihan A.; Kristensen, Vessela N.; Li, Donghui; Parl, Fritz F.; Rylander-Rudqvist, Tove; Soucek, Pavel; et al. (2007-01-15)
      The association between the cytochrome P-450 1B1 (CYP1B1) Val432Leu polymorphism and breast cancer was assessed through a meta-analysis of all published case-control studies and a pooled analysis of both published and unpublished case-control studies from the Genetic Susceptibility to Environmental Carcinogens (GSEC) database ( www.upci.upmc.edu/research/ccps/ccontrol/g_intro.html ). GSEC is a collaborative project that gathers information on studies of metabolic gene polymorphisms and cancer. Thirteen articles were included in the meta-analysis (14,331 subjects; 7,514 cases, 6,817 controls); nine data sets were included in the pooled analysis (6,842 subjects; 3,391 cases, 3,451 controls). A summary meta- or pooled estimate of the association between the CYP1B1 Val432Leu polymorphism and breast cancer could not be calculated because of statistically significant heterogeneity in the point estimates among studies. No association between the CYP1B1 Val432Leu polymorphism and breast cancer was observed in Asians (for Val/Val and Val/Leu combined, odds ratio (OR) = 1.0, 95% confidence interval (CI): 0.8, 1.2). An inverse association was observed in populations of mixed/African origin (OR = 0.8, 95% CI: 0.7, 0.9). The pooled analysis suggested a possible association in Caucasians (for Val/Val and Val/Leu combined, OR = 1.5, 95% CI: 1.1, 2.1), with effect modification across age categories. The observed effect of age on the association in Caucasians indicates that further studies are needed on the role of CYP1B1 Val432Leu in estrogen metabolism according to age, ethnicity, and menopausal status.
    • Meta- and pooled analyses of the methylenetetrahydrofolate reductase C677T and A1298C polymorphisms and gastric cancer risk: a huge-GSEC review.

      Boccia, Stefania; Hung, Rayjean; Ricciardi, Gualtiero; Gianfagna, Francesco; Ebert, Matthias P.A.; Fang, Jing-Yuan; Gao, Chang-Ming; Gotze, Tobias; Graziano, Francesco; Lacasana-Navarro, Marina; et al. (2008-03-01)
      Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the metabolism of folate, whose role in gastric carcinogenesis is controversial. The authors performed a meta-analysis and individual data pooled analysis of case-control studies that examined the association between C677T and A1298C polymorphisms (the former being associated with low folate serum levels) and gastric cancer (meta-analyses: 16 studies, 2,727 cases and 4,640 controls for C677T and seven studies, 1,223 cases and 2,015 controls for A1298C; pooled analyses: nine studies, 1,540 cases and 2,577 controls for C677T and five studies, 1,146 cases and 1,549 controls for A1298C). An increased risk was found for MTHFR 677 TT in the meta-analysis (odds ratio (OR) = 1.52, 95% confidence interval (CI): 1.31, 1.77) and pooled analysis (OR = 1.49, 95% CI: 1.14, 1.95). No association resulted for MTHFR 1298 CC (meta-OR = 0.94, 95% CI: 0.65, 1.35; pooled OR = 0.90, 95% CI: 0.69, 1.34). Results from the pooled analysis of four studies on C677T stratified according to folate levels showed an increased risk for individuals with low (OR = 2.05, 95% CI: 1.13, 3.72) versus high (OR = 0.95, 95% CI: 0.54, 1.67) folate levels. Overall, these findings support the hypothesis that folate plays a role in gastric carcinogenesis.
    • Meta- and pooled analysis of GSTT1 and lung cancer: a HuGE-GSEC review.

      Raimondi, S.; Paracchini, V.; Autrup, H.; Barros-Dios, J.M.; Benhamou, S.; Boffetta, P.; Cote, M.L.; Dialyna, I.A.; Dolzan, V.; Filiberti, R.; et al. (2006-12-01)
      Lung cancer is the most common malignancy in the Western world, and the main risk factor is tobacco smoking. Polymorphisms in metabolic genes may modulate the risk associated with environmental factors. The glutathione S-transferase theta 1 gene (GSTT1) is a particularly attractive candidate for lung cancer susceptibility because of its involvement in the metabolism of polycyclic aromatic hydrocarbons found in tobacco smoke and of other chemicals, pesticides, and industrial solvents. The frequency of the GSTT1 null genotype is lower among Caucasians (10-20%) than among Asians (50-60%). The authors present a meta- and a pooled analysis of case-control, genotype-based studies that examined the association between GSTT1 and lung cancer (34 studies, 7,629 cases and 10,087 controls for the meta-analysis; 34 studies, 7,044 cases and 10,000 controls for the pooled analysis). No association was observed between GSTT1 deletion and lung cancer for Caucasians (odds ratio (OR) = 0.99, 95% confidence interval (CI): 0.87, 1.12); for Asians, a positive association was found (OR = 1.28, 95% CI: 1.10, 1.49). In the pooled analysis, the odds ratios were not significant for either Asians (OR = 0.97, 95% CI: 0.83, 1.13) or Caucasians (OR = 1.09, 95% CI: 0.99, 1.21). No significant interaction was observed between GSTT1 and smoking on lung cancer, whereas GSTT1 appeared to modulate occupational-related lung cancer.
    • Metabolic activation of benzo[a]pyrene in vitro by hepatic cytochrome P450 contrasts with detoxification in vivo: experiments with hepatic cytochrome P450 reductase null mice.

      Arlt, Volker M.; Stiborova, Marie; Henderson, Colin J.; Thiemann, Markus; Frei, Eva; Aimova, Dagmar; Singh, Rajinder; Gamboa da Costa, Goncalo; Schmitz, Oliver J.; Farmer, Peter B.; et al. (2008-03)
      Many studies using mammalian cellular and subcellular systems have demonstrated that polycyclic aromatic hydrocarbons, including benzo[a]pyrene (BaP), are metabolically activated by cytochrome P450s (CYPs). In order to evaluate the role of hepatic versus extra-hepatic metabolism of BaP and its pharmacokinetics, we used the hepatic cytochrome P450 reductase null (HRN) mouse model, in which cytochrome P450 oxidoreductase, the unique electron donor to CYPs, is deleted specifically in hepatocytes, resulting in the loss of essentially all hepatic CYP function. HRN and wild-type (WT) mice were treated intraperitoneally (i.p.) with 125 mg/kg body wt BaP daily for up to 5 days. Clearance of BaP from blood was analysed by high-performance liquid chromatography with fluorescence detection. DNA adduct levels were measured by (32)P-post-labelling analysis with structural confirmation of the formation of 10-(deoxyguanosin-N(2)-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene by liquid chromatography-tandem mass spectrometry analysis. Hepatic microsomes isolated from BaP-treated and untreated mice were also incubated with BaP and DNA in vitro. BaP-DNA adduct formation was up to 7-fold lower with the microsomes from HRN mice than with that from WT mice. Most of the hepatic microsomal activation of BaP in vitro was attributable to CYP1A. Pharmacokinetic analysis of BaP in blood revealed no significant differences between HRN and WT mice. BaP-DNA adduct levels were higher in the livers (up to 13-fold) and elevated in several extra-hepatic tissues of HRN mice (by 1.7- to 2.6-fold) relative to WT mice. These data reveal an apparent paradox, whereby hepatic CYP enzymes appear to be more important for detoxification of BaP in vivo, despite being involved in its metabolic activation in vitro.
    • Metabolic activation of carcinogenic aristolochic acid, a risk factor for Balkan endemic nephropathy.

      Stiborova, Marie; Frei, Eva; Arlt, Volker M.; Schmeiser, Heinz H. (2008-09-24)
      Aristolochic acid (AA), a naturally occurring nephrotoxin and carcinogen, is associated with tumor development in patients suffering from Chinese herbs nephropathy (now termed aristolochic acid nephropathy, AAN) and may also be a cause for the development of a similar type of nephropathy, the Balkan endemic nephropathy (BEN). Major DNA adducts [7-(deoxyadenosin-N6-yl)-aristolactam and 7-(deoxyguanosin-N2-yl)aristolactam] formed from AA after reductive metabolic activation were found in renal tissues of patients with both diseases. Understanding which human enzymes are involved in AA activation and/or detoxication is important in the assessment of an individual's susceptibility to this plant carcinogen. This paper reviews major hepatic and renal enzymes responsible for AA-DNA adduct formation in humans. Phase I biotransformation enzymes play a crucial role in the metabolic activation of AA to species forming DNA adducts, while a role of phase II enzymes in this process is questionable. Most of the activation of AA in human hepatic microsomes is mediated by cytochrome P450 (CYP) 1A2 and, to a lower extent, by CYP1A1; NADPH:CYP reductase plays a minor role. In human renal microsomes NADPH:CYP reductase is more effective in AA activation. Prostaglandin H synthase (cyclooxygenase, COX) is another enzyme activating AA in human renal microsomes. Among the cytosolic reductases, NAD(P)H:quinone oxidoreductase (NQO1) is the most efficient in the activation of AA in human liver and kidney. Studies with purified enzymes confirmed the importance of CYPs, NADPH:CYP reductase, COX and NQO1 in the AA activation. The orientation of AA in the active sites of human CYP1A1, -1A2 and NQO1 was predicted from molecular modeling and explains the strong reductive potential of these enzymes for AA detected experimentally. We hypothesized that inter-individual variations in expressions and activities of enzymes activating AA may be one of the causes responsible for the different susceptibilities to this carcinogen reflected in the development of AA-induced nephropathies and associated urothelial cancer.
    • Metabolic genotypes as modulators of asbestos-related pleural malignant mesothelioma risk: a comparison of Finnish and Italian populations.

      Neri, Monica; Taioli, Emanuela; Filiberti, Rosangela; Paolo Ivaldi, Giovanni; Aldo Canessa, Pier; Verna, Anna; Marroni, Paola; Puntoni, Riccardo; Hirvonen, Ari; Garte, Seymour (2006-07)
      The role of CYP1A1, GSTM1, GSTT1, EPHX1, and NAT2 genotypes in susceptibility to malignant mesothelioma (MM) was compared in two case-control studies, previously conducted in two countries where different types of asbestos fibers have been used [Hirvonen et al., 1995. Inherited GSTM1 and NAT2 defects as concurrent risk modifiers in asbestos-related human malignant mesothelioma. Cancer Res. 55, 2981-2983; Hirvonen et al., 1996. Glutathione S-Transferase and N-Acetyltransferase genotypes and asbestos-associated pulmonary disorders. J. Natl. Cancer Inst.88, 1853-1856; Neri et al., 2005. Pleural malignant mesothelioma, genetic susceptibility and asbestos exposure. Mutat. Res. 592, 36-44]. Fifty-seven asbestos-exposed MM patients and 255 controls were recruited in Italy, 48 cases and 121 controls in Finland. In order to make the two studies comparable, they have been updated and new genotyping analyses have been performed. The NAT2 fast acetylator and EPHX1 low-activity genotypes were positively associated with MM in the Italian study, while they were negatively associated with this malignancy in the Finnish one. A combined significant effect was also observed in the Italian study for the NAT2 fast acetylator and EPHX1 low-activity genotypes, while this combination was protective in the Finnish study. Combination of NAT2 fast acetylator and GSTM1 null genotype posed a significantly increased risk of MM in the Italian, but not in the Finnish study. The opposite results obtained in Finland and Italy may be ascribed to random chance, but a role may be hypothesized for the fact that different types of asbestos have been used in the two countries.
    • Modszer osszehasonlito vizsgalatok policiklusos aromas szenhidrogen (PAH) modellvegyuletek DNS adduktjainak meghatarozasara. (in Hungarian)

      Kovacs, Katalin; Panagiotis, Georgiadis; Stella, Kaila; Anna, Livia; Schoket, Bernadette; Soterios, Kyrtopoulos (2011-11)
    • Modulation of oxidative DNA damage repair by the diet, inflammation and neoplastic transformation.

      Tudek, B.; Swoboda, M.; Kowalczyk, P.; Olinski, R. (2006-11)
      Oxidative DNA damage and DNA repair may mediate several cellular processes, like replication and transcription, mutagenesis and apoptosis and thus may be important for the organism development as well as its pathogenesis, including cancer. Activity of DNA repair enzymes can depend on many factors, such as gene polymorphism, mRNA and protein level, as well as enzymes activation and inhibition. Modulation of base excision repair pathway eliminating from DNA oxidatively formed lesions may be caused by the diet, inflammation and neoplastic transformation. Reactive oxygen species and some diet components induce transcription of several Base Excision Repair enzymes, e.g. major human AP-endonuclease, (APE1) and 8-oxoG-DNA glycosylase (OGG1). The carcinogenic process in human lung decreases repair activity for 8-oxoGin transcription independent manner, but increases repair activity of epsilon A and epsilon C, as measured in tumors and unchanged lung tissues of lung cancer patients. Thus, modulation of repair enzymes activities may be a cell response on their way to differentiation ot neoplastic transformation.
    • Molecular evidence for an involvement of organic anion transporters (OATs) in aristolochic acid nephropathy.

      Bakhiya, Nadiya; Arlt, Volker M.; Bahn, Andrew; Burckhardt, Gerhard; Phillips, David H.; Glatt, Hansruedi (2009-10-01)
      Aristolochic acid (AA), present in Aristolochia species, is the major causative agent in the development of severe renal failure and urothelial cancers in patients with AA nephropathy. It may also be a cause of Balkan endemic nephropathy. Epithelial cells of the proximal tubule are the primary cellular target of AA. To study whether organic anion transporters (OATs) expressed in proximal tubule cells are involved in uptake of AA, we used human epithelial kidney (HEK293) cells stably expressing human (h) OAT1, OAT3 or OAT4. AA potently inhibited the uptake of characteristic substrates, p-aminohippurate for hOAT1 and estrone sulfate for hOAT3 and hOAT4. Aristolochic acid I (AAI), the more cytotoxic and genotoxic AA congener, exhibited high affinity for hOAT1 (K(i)=0.6 microM) as well as hOAT3 (K(i)=0.5 microM), and lower affinity for hOAT4 (K(i)=20.6 microM). Subsequently, AAI-DNA adduct formation (investigated by (32)P-postlabelling) was used as a measure of AAI uptake. Significantly higher levels of adducts occurred in hOAT-expressing cells than in control cells: this effect was abolished in the presence of the OAT inhibitor probenecid. In Xenopus laevis oocytes hOAT-mediated efflux of p-aminohippurate was trans-stimulated by extracellular AA, providing further molecular evidence for AA translocation by hOATs. Our study indicates that OATs can mediate the uptake of AA into proximal tubule cells and thereby participate in kidney cell damage by this toxin.