• ³²P-HPLC analysis of N1-(2-carboxy-2-hydroxyethyl)deoxyadenosine: a DNA adduct of the acrylamide-derived epoxide glycidamide.

      Kotova, Natalia; Juren, Tina; Myohanen, Kirsi; Cornelius, Michael; Abramsson-Zetterberg, Lilianne; Backman, Josefin; Menzel, Ulrike; Rydberg, Per; Kronberg, Leif; Vahakangas, Kirsi; et al. (2011-11-10)
      Acrylamide (AA) is produced in many types of food products cooked or processed at high temperature. AA is metabolized to the epoxide glycidamide (GA), which can bind to deoxyguanosine and deoxyadenosine in DNA. The GA-derived N7-guanine and N3-adenine adducts are the only products which so far have been analysed in vivo. Because of previous excellent experience from analysis of adducts to N1-adenine, the aim of our study was to investigate if the N1-adenine adduct of GA could be used as a biomarker of AA exposure. A ³²P-postlabelling method was developed and tested (a) on DNA modified in vitro with GA, (b) on cells treated with GA and (c) on liver DNA from mice treated with AA. The N1-adenine adduct of GA (analysed after conversion to N⁶-GA-deoxyadenosine-5'-monophosphate) was easily detected in DNA reacted with GA and in DNA from cells exposed to GA, but not in DNA from mice treated with AA. The reason for this is currently not clearly understood, but some of the possible contributing factors are discussed. The application of the method in other experimental conditions should be further pursued in order to solve this matter.
    • Phase I enzyme genotypes and their toxicologically relevant phenotypes.

      Godschalk, Roger; van Schooten, Frederik Jan (Nofer Institute of Occupational Medicine, 2008)
    • Phase II enzyme genotypes and their toxicologically relevant phenotypes.

      Hirvonen, Ari (Nofer Institute of Occupational Medicine, 2008)
    • Phenotyping for DNA repair capacity.

      Decordier, Ilse; Loock, Kim Vande; Kirsch-Volders, Micheline (2010-10)
      The ability to repair DNA damage is strongly associated with the risk of cancer and other human diseases as it is essential for maintenance of genome stability. Moreover, DNA repair capacity is an important factor contributing to the inter-individual variability in mutagen exposure, cancer development and treatment through an individualized adjusted therapy. In addition to genotypes, functional phenotypic assays which integrate the different pathways provide useful tools to explore the role of DNA repair in cancer susceptibility. This review compares the presently available cellular DNA repair phenotype assays based on their characteristics, and discusses their advantages and limitations. Assays for assessment of DNA repair phenotype should be well characterized in terms of reliability, validity, sensitivity, inter- and intra-individual variability, and cancer predictivity. Our comparison reveals that the G₁ and G₂ challenge assays, although labour-intensive, can be considered as very useful assays to investigate DNA repair phenotype. They have been successfully applied to investigate repair capacity of both cancer patients and environmentally exposed populations, and can detect deficiencies in different repair pathways. Moreover, these assays allow to predict the cancer therapy responses and to investigate the cancer prognosis. Nevertheless, the choice of the assay depends on the scientific question addressed and on the objective of its application and more prospective studies are needed since the phenotype could reflect the pathophysiological alterations in the patient secondary to the disease.
    • Phosphorylation of xenobiotic-metabolizing cytochromes P450.

      Oesch-Bartlomowicz, B.; Oesch, F. (2008-11)
      The regulation of cytochromes P450 (CYPs) by induction mediated by xenobiotics is well known. Our team has discovered an additional important regulation of xenobiotic-metabolizing CYPs by phosphorylation. Individual CYPs are phosphorylated by different protein kinases, leading to CYP isoenzyme-selective changes in the metabolism of individual substrates and consequent profound changes in the control of mutagenic and cytotoxic metabolites. Some CYPs are phosphorylated by protein kinase C and some by the cyclic adenosine monophosphate (cAMP) dependent protein kinase A. We found that cAMP not only leads to drastic changes in the activity of individual CYPs, but also drastic changes in the nuclear localization of the CYP-related transcription factor Ah receptor (AHR). The consequences are very different from those of AHR nuclear translocation mediated by its classic ligands (such as dioxin and many polycyclic aromatic hydrocarbons) and may represent the long-sought physiological function of the AHR. The disturbance of this physiological function of AHR by extremely persistent high-affinity xenobiotic ligands such as dioxin may represent the most important contributing factor for their potent toxicity.
    • Phosphotriesters: Long lifetime biomarkers.

      Le Pla, Rachel C.; Jones, G. Don D.; University of Leicester, UK (The Nofer Institute of Occupational Medicine, 2006)
      In addition to reacting with DNA bases, many genotoxic agents react with the oxygen of the internucleotide phosphodiester linkages to form phosphotriester adducts. Several studies have shown that phosphotriester lesions have a half-life that exceeds that of any other DNA alkylation product. The relative abundance of phosphotriesters depends upon the alkylating character of the agent. The role of phosphotriester adducts in carcinogenesis is unknown. Mutation resulting from phosphotriester formation has not been fully studied, but such adducts may influence cellular function by altering the binding of proteins to DNA.
    • Plasma 25-hydroxyvitamin D and premenopausal breast cancer risk in a German case-control study.

      Abbas, Sascha; Chang-Claude, Jenny; Linseisen, Jakob (2009-01-01)
      Laboratory and epidemiological data have linked vitamin D to breast cancer prevention. Beside dietary intake, endogenous production of vitamin D substantially contributes to a subject's vitamin D status. Most studies, however, have assessed dietary intake only. Although differential effects of vitamin D on premenopausal and postmenopausal breast cancer have been discussed, this is the first study to investigate the association of plasma 25-hydroxyvitamin D [25(OH)D], as indicator of the overall vitamin D status, with breast cancer risk with restriction to premenopausal women only. We used data of a population-based case-control study comprising 289 cases and 595 matched controls. Information on sociodemographic and breast cancer risk factors was collected by questionnaire and plasma 25(OH)D was measured by enzyme immunoassay. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression. We observed a significant inverse association between breast cancer risk and plasma 25(OH)D concentrations. Compared with the lowest category (<30 nmol/L), the ORs (95% CI) for the upper categories (30-45, 45-60, >or=60 nmol/L) were 0.68 (0.43-1.07), 0.59 (0.37-0.94) and 0.45 (0.29-0.70), respectively (p(trend) = 0.0006). The association was shown to be nonlinear (p(nonlinearity) = 0.06) in fractional polynomial analysis with a stronger effect in women at low plasma 25(OH)D levels, providing some evidence of a threshold effect (at circa 50 nmol/L). The association was stronger in progesterone receptor negative tumors, with suggestive evidence of effect heterogeneity (p(heterogeneity) = 0.05, case-only model). Our findings support a protective effect of vitamin D for premenopausal breast cancer.
    • Plasma cytokines and future risk of non-Hodgkin lymphoma (NHL): a case-control study nested in the Italian European Prospective Investigation into Cancer and Nutrition.

      Saberi Hosnijeh, Fatemeh; Krop, Esmeralda J.M.; Scoccianti, Chiara; Krogh, Vittorio; Palli, Domenico; Panico, Salvatore; Tumino, Rosario; Sacredote, Carlotta; Nawroly, Niga; Portengen, Lutzen; et al. (2010-06)
      Recently, biological markers related to the immune system such as cytokines have been studied to further understand the etiology of non-Hodgkin Lymphoma (NHL). However, to date, there are no studies that have studied cytokine levels prospectively in relation to NHL risk in the general population.
    • Polychlorinated biphenyls in Spanish adults: determinants of serum concentrations.

      Agudo, Antonio; Goni, Fernando; Etxeandia, Arsenio; Vives, Asuncion; Millan, Esmeralda; Lopez, Raul; Amiano, Pilar; Ardanaz, Eva; Barricarte, Aurelio; Chirlaque, M. Dolores; et al. (2009-07)
      BACKGROUND: Polychlorinated biphenyls (PCBs) are persistent compounds that may pose an environmental hazard to humans, food being the main source of exposure for the general population. OBJECTIVE: To measure the serum concentrations of the main PCBs in subjects from the general population in Spain, and to assess potential determinants of such concentrations. METHODS: Serum was obtained from blood samples of 953 subjects aged 35-64 years, residents in five Spanish regions (three from the North and two from the South), randomly selected from the EPIC-Spain cohort. Blood collection took place during 1992-1996 and four PCB congeners (118, 138, 153 and 180) were determined by means of gas chromatography with electron-capture detection (GC-ECD). RESULTS: The concentration of total PCBs was 459 ng/g lipids (or 3.1 microg/l); the corresponding figures for PCB 153 were 186 ng/g lipids and 1.25 microg/l. Men had higher values than women, PCB levels increased with age, and serum concentration of PCBs was higher in northern regions. Body mass index (BMI) was inversely related to PCB concentrations, and fish intake was the dietary factor showing the greatest association with serum PCBs. The pattern described was similar for each congener separately. CONCLUSIONS: We found concentrations similar to those reported in European countries where blood collection was carried during the same period. Regional differences within Spain are not fully explained by anthropometric or dietary factors. The inverse association with BMI suggests that in the mid-1990s there was still ongoing or recent exposure to PCBs in Spain.
    • Polycyclic aromatic hydrocarbons as skin carcinogens: comparison of benzo[a]pyrene, dibenzo[def,p]chrysene and three environmental mixtures in the FVB/N mouse.

      Siddens, Lisbeth K.; Larkin, Andrew; Krueger, Sharon K.; Bradfield, Christopher A.; Waters, Katrina M.; Tilton, Susan C.; Pereira, Cliff B.; Löhr, Christiane V.; Arlt, Volker M.; Phillips, David H.; et al. (2012-11-01)
      The polycyclic aromatic hydrocarbon (PAH), benzo[a]pyrene (BaP), was compared to dibenzo[def,p]chrysene (DBC) and combinations of three environmental PAH mixtures (coal tar, diesel particulate and cigarette smoke condensate) using a two stage, FVB/N mouse skin tumor model. DBC (4nmol) was most potent, reaching 100% tumor incidence with a shorter latency to tumor formation, less than 20 weeks of 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion compared to all other treatments. Multiplicity was 4 times greater than BaP (400 nmol). Both PAHs produced primarily papillomas followed by squamous cell carcinoma and carcinoma in situ. Diesel particulate extract (1 mg SRM 1650b; mix 1) did not differ from toluene controls and failed to elicit a carcinogenic response. Addition of coal tar extract (1 mg SRM 1597a; mix 2) produced a response similar to BaP. Further addition of 2 mg of cigarette smoke condensate (mix 3) did not alter the response with mix 2. PAH-DNA adducts measured in epidermis 12 h post initiation and analyzed by ³²P post-labeling, did not correlate with tumor incidence. PAH-dependent alteration in transcriptome of skin 12 h post initiation was assessed by microarray. Principal component analysis (sum of all treatments) of the 922 significantly altered genes (p<0.05), showed DBC and BaP to cluster distinct from PAH mixtures and each other. BaP and mixtures up-regulated phase 1 and phase 2 metabolizing enzymes while DBC did not. The carcinogenicity with DBC and two of the mixtures was much greater than would be predicted based on published Relative Potency Factors (RPFs).
    • Polymorphisms in DNA repair genes, smoking, and bladder cancer risk: findings from the international consortium of bladder cancer.

      Stern, Mariana C.; Lin, Jie; Figueroa, Jonine D.; Kelsey, Karl T.; Kiltie, Anne E.; Yuan, Jian-Min; Matullo, Giuseppe; Fletcher, Tony; Benhamou, Simone; Taylor, Jack A.; et al. (2009-09-01)
      Tobacco smoking is the most important and well-established bladder cancer risk factor and a rich source of chemical carcinogens and reactive oxygen species that can induce damage to DNA in urothelial cells. Therefore, common variation in DNA repair genes might modify bladder cancer risk. In this study, we present results from meta-analyses and pooled analyses conducted as part of the International Consortium of Bladder Cancer. We included data on 10 single nucleotide polymorphisms corresponding to seven DNA repair genes from 13 studies. Pooled analyses and meta-analyses included 5,282 cases and 5,954 controls of non-Latino white origin. We found evidence for weak but consistent associations with ERCC2 D312N [rs1799793; per-allele odds ratio (OR), 1.10; 95% confidence interval (95% CI), 1.01-1.19; P = 0.021], NBN E185Q (rs1805794; per-allele OR, 1.09; 95% CI, 1.01-1.18; P = 0.028), and XPC A499V (rs2228000; per-allele OR, 1.10; 95% CI, 1.00-1.21; P = 0.044). The association with NBN E185Q was limited to ever smokers (interaction P = 0.002) and was strongest for the highest levels of smoking dose and smoking duration. Overall, our study provides the strongest evidence to date for a role of common variants in DNA repair genes in bladder carcinogenesis.
    • Pooled analysis and meta-analysis of the glutathione S-transferase P1 Ile 105Val polymorphism and bladder cancer: a HuGE-GSEC review.

      Kellen, Eliane; Hemelt, Marjolein; Broberg, Karin; Golka, Klaus; Kristensen, Vessela Nedelcheva; Hung, Rayjean J.; Matullo, Giuseppe; Mittal, Rama D.; Porru, Stefano; Povey, Andrew; et al. (2007-06-01)
      The glutathione S-transferase P1 genotype (GSTP1) is involved in the inactivation of cigarette smoke carcinogens, and sequence variation in the gene may alter bladder cancer susceptibility. To examine the association between GSTP1Ile 105Val and bladder cancer, the authors undertook a meta- and pooled analysis. Summary crude and adjusted odds ratios and corresponding 95% confidence intervals were pooled by using a random-effects model. In the meta-analysis (16 studies, 4,273 cases and 5,081 controls), the unadjusted summary odds ratios for GSTP1 Ile/Val and Val/Val compared with GSTP1 Ile/Ile were 1.54 (95% confidence interval: 1.21, 1.99; p < 0.001) and 2.17 (95% confidence interval: 1.27, 3.71; p = 0.005). The association appeared to be the strongest in Asian countries. When the analysis was limited to European descendents (nine studies), the summary odds ratio decreased (odds ratio = 1.24, 95% confidence interval: 1.00, 1.52) (Q = 17.50; p = 0.02). All relevant data previously contributed to the International Study on Genetic Susceptibility to Environmental Carcinogens were pooled (eight studies, 1,305 cases and 1,558 controls). The summary odds ratios were similar to the ones from the meta-analysis. Case-only analyses did not detect an interaction between the GSTP1 genotype and smoking status (never/ever). GSTP1 Ile 105Val appears to be associated with a modest increase in the risk of bladder cancer.
    • Pooled analysis of studies on DNA adducts and dietary vitamins.

      Ragin, Camille; Minor, Aerie; Agudo, Antonio; Farmer, Peter; Garte, Seymour; Gonzales, Carlos; Kalina, Ivan; Matullo, Giuseppe; Popov, Todor; Palli, Domenico; et al. (2010-10)
      OBJECTIVES: There is some evidence that dietary components that are rich in antioxidant and vitamins are inversely associated with DNA adduct levels induced by environmental carcinogens such as polycyclic aromatic hydrocarbons, although the epidemiologic data are inconsistent. This study addresses the association between vitamins, DNA adducts and smoking. METHODS: A combined analysis of individual data on the association between bulky DNA adducts and dietary vitamins was conducted. A Medline search was performed to identify studies on healthy subjects in which smoking and vitamins intake information were available, and bulky DNA adducts were measured in peripheral blood with 32P-postlabelling. Eight published studies met the eligibility criteria, and individual data from 7 data sets including 2758 subjects were obtained. GSTM1 and GSTT1 were also available on all the subjects. RESULTS: Vitamin E was inversely significantly associated with DNA adducts after adjustment for possible confounding factors. Vitamins A and C were not independent predictors of DNA adducts. A stratified analysis showed that vitamin A had a significant inverse association with DNA adducts in ever smokers only. CONCLUSIONS: This result is relevant to planning any future chemo-preventive interventions directed to high risk subgroups of the population, for cancer prevention.
    • Predicting the physiological relevance of in vitro cancer preventive activities of phytochemicals.

      Howells, Lynne M.; Moiseeva, Elena P.; Neal, Christopher P.; Foreman, Bethany E.; Andreadi, Catherine K.; Sun, Yi-yang; Hudson, E. Ann; Manson, Margaret M (2007)
      There is growing interest in the ability of phytochemicals to prevent chronic diseases, such as cancer and heart disease. However, some of these agents have poor bioavailability and many of the in-depth studies into their mechanisms of action have been carried out in vitro using doses which are unachievable in humans. In order to optimize the design of chemopreventive treatment, it is important to determine which of the many reported mechanisms of action are clinically relevant. In this review we consider the physiologically achievable doses for a few of the best studied agents (indole-3-carbinol, diindolylmethane, curcumin, epigallocatechin-3-gallate and resveratrol) and summarize the data derived from studies using these low concentrations in cell culture. We then cite examples of in vitro effects which have been observed in vivo. Finally, the ability of agent combinations to act synergistically or antagonistically is considered. We conclude that each of the compounds shows an encouraging range of activities in vitro at concentrations which are likely to be physiologically relevant. There are also many examples of in vivo studies which validate in vitro observations. An important consideration is that combinations of agents can result in significant activity at concentrations where any single agent is inactive. Thus, for each of the compounds reviewed here, in vitro studies have provided useful insights into their mechanisms of action in humans. However, data are lacking on the full range of activities at low doses in vitro and the benefits or otherwise of combinations in vivo.
    • Predicting the physiological relevance of in vitro cancer preventive activities of phytochemicals.

      Howells, Lynne M.; Moiseeva, Elena P.; Neal, Christopher P.; Foreman, Bethany E.; Andreadi, Catherine K.; Sun, Yi-yang; Hudson, E. Ann; Manson, Margaret M. (2007-09)
      There is growing interest in the ability of phytochemicals to prevent chronic diseases, such as cancer and heart disease. However, some of these agents have poor bioavailability and many of the in-depth studies into their mechanisms of action have been carried out in vitro using doses which are unachievable in humans. In order to optimize the design of chemopreventive treatment, it is important to determine which of the many reported mechanisms of action are clinically relevant. In this review we consider the physiologically achievable doses for a few of the best studied agents (indole-3-carbinol, diindolylmethane, curcumin, epigallocatechin-3-gallate and resveratrol) and summarize the data derived from studies using these low concentrations in cell culture. We then cite examples of in vitro effects which have been observed in vivo. Finally, the ability of agent combinations to act synergistically or antagonistically is considered. We conclude that each of the compounds shows an encouraging range of activities in vitro at concentrations which are likely to be physiologically relevant. There are also many examples of in vivo studies which validate in vitro observations. An important consideration is that combinations of agents can result in significant activity at concentrations where any single agent is inactive. Thus, for each of the compounds reviewed here, in vitro studies have provided useful insights into their mechanisms of action in humans. However, data are lacking on the full range of activities at low doses in vitro and the benefits or otherwise of combinations in vivo.
    • PRIMA-1 reactivates mutant p53 by covalent binding to the core domain.

      Lambert, Jeremy M. R.; Gorzov, Petr; Veprintsev, Dimitry B.; Soderqvist, Maja; Segerback, Dan; Bergman, Jan; Fersht, Alan R.; Hainaut, Pierre; Wiman, Klas G.; Bykov, Vladimir J. N. (2009-05-05)
      Restoration of wild-type p53 expression triggers cell death and eliminates tumors in vivo. The identification of mutant p53-reactivating small molecules such as PRIMA-1 opens possibilities for the development of more efficient anticancer drugs. Although the biological effects of PRIMA-1 are well demonstrated, little is known about its molecular mechanism of action. We show here that PRIMA-1 is converted to compounds that form adducts with thiols in mutant p53. Covalent modification of mutant p53 per se is sufficient to induce apoptosis in tumor cells. These findings might facilitate the design of more potent and specific mutant p53-targeting anticancer drugs.
    • Progress in high-throughput assays of MGMT and APE1 activities in cell extracts.

      Georgiadis, Panagiotis; Polychronaki, Nektaria; Kyrtopoulos, Soterios A. (2012-05-17)
      DNA repair activity is of interest as a potential biomarker of individual susceptibility to genotoxic agents. In view of the current trend for exploitation of large cohorts in molecular epidemiology projects, there is a pressing need for the development of phenotypic DNA repair assays that are high-throughput, very sensitive, inexpensive and reliable. Towards this goal we have developed and validated two phenotypic assays for the measurement of two DNA repair enzymes in cell extracts: (1) O(6)-methylguanine-DNA-methyltransferase (MGMT), which repairs the O(6)-alkylguanine-type of adducts induced in DNA by alkylating genotoxins; and (2) apurinic/apyrimidinic endonuclease 1 (APE 1), which participates in base excision repair (BER) by causing a rate-limiting DNA strand cleavage 5' to the abasic sites. The MGMT assay makes use of the fact that: (a) the enzyme works by irreversibly transferring the alkyl group from the O(6) position of guanine to a cystein residue in its active site and thereby becomes inactivated and (b) that the free base O(6)-benzylguanine (BG) is a very good substrate for MGMT. In the new assay, cell extracts are incubated with BG tagged with biotin and the resulting MGMT-BG-biotin complex is immobilized on anti-MGMT-coated microtiter plates, followed by quantitation using streptavidin-conjugated alkaline phosphatase and a chemiluminescence-producing substrate. A one-step/one-tube phenotypic assay for APE1 activity has been developed based on the use of a fluorescent molecular beacon (partially self-complementary oligonucleotide with a hairpin-loop structure carrying a fluorophore and a quencher at each end). It also contains a single tetrahydrofuran residue (THF) which is recognized and cleaved by APE1, and the subsequently formed single-stranded oligomer becomes a fluorescence signal emitter. Both assays are highly sensitive, require very small amounts of protein extracts, are relatively inexpensive and can be easily automated. They have been extensively validated and are being used in the context of large-scale molecular epidemiology studies.
    • Prospective study of physical activity and risk of primary adenocarcinomas of the oesophagus and stomach in the EPIC (European Prospective Investigation into Cancer and nutrition) cohort.

      Huerta, Jose Maria; Navarro, Carmen; Chirlaque, Maria-Dolores; Tormo, Maria-Jose; Steindorf, Karen; Buckland, Genevieve; Carneiro, Fatima; Johnsen, Nina Fons; Overvad, Kim; Stegger, Jakob; et al. (2010-05)
      OBJECTIVE: To analyse the association between types of physical activity (occupational, recreational and household, vigorous and overall) and risk of primary oesophageal (OAC) or gastric adenocarcinoma (GAC). METHODS: From nine European countries, 420,449 participants were recruited between 1991 and 2000 and followed-up for a mean of 8.8 years to register incident GAC and OAC. Information on physical activity (PA), diet, lifestyle and health-related variables was obtained at baseline. Helicobacter pylori infection status was considered in a subset of 1,211 participants. Analyses were repeated by tumour site (cardia/non-cardia) and histological type (intestinal/diffuse). RESULTS: During the follow-up, 410 GAC and 80 OAC occurred. A lower risk of overall and non-cardia GAC was found for increasing levels of a PA index which combined occupational PA with weekly time spent in sports and cycling. The hazard ratio (HR) of GAC was 0.69, 95% CI: 0.50-0.94, for the comparison between active and inactive participants according to the PA index (HR = 0.44, 95% CI:0.26-0.74, for non-cardia GAC). No effect was found for cardia tumours or histological subtypes of GAC. PA of any kind was not associated with OAC. CONCLUSIONS: Overall and distal (non-cardia) gastric tumours were inversely associated with time spent on cycling and sports and a total PA index. No association was found for any type of PA and risk of cardia cancers of the stomach.
    • Prospective study of urinary excretion of 7-methylguanine and the risk of lung cancer: Effect modification by mu class glutathione-S-transferases.

      Loft, Steffen; Svoboda, Peter; Kasai, Hiroshi; Tjonneland, Anne; Moller, Peter; Sorensen, Mette; Overvad, Kim; Autrup, Herman; Raaschou-Nielsen, Ole (2007-10-01)
      Nitrosamines are mainly mutagenic through methylation of DNA. 7-Methylguanine (m(7)Gua) is a product of base excision repair and spontaneous depurination of such lesions in DNA and a metabolite from RNA. Associations between urinary excretion of m(7)Gua and risk of lung cancer were examined in a population-based cohort of 25,717 men and 27,972 women aged 50-64 years. During 3-7 years follow-up 260 cases with lung cancer were identified and a subcohort of 263 individuals matched on sex, age and smoking duration was selected for comparison. Urine collected at entry was analyzed for m(7)Gua by HPLC. Effect modification by glutathione-S-transferases GSTM1, GSTM3, GSTT1 and GSTP1 was investigated. We found higher excretion of m(7)Gua among current smokers than among former smokers. The IRR (incidence rate ratio) of lung cancer was 1.20 (95% CI: 1.00-1.43) per doubling of m(7)Gua excretion in unadjusted analysis and 1.12 (95% CI: 0.93-1.35) after adjustment for smoking status, intensity and duration at entry. This association was mainly present among current smokers. Comparing the highest with the lowest tertile of m(7)Gua excretion the IRR of lung cancer was 1.75 (95% CI: 1.04-2.95) irrespective of genotype and 2.75 (95% CI: 1.33-5.81) in subjects with GSTM1 null genotype. If not caused by residual confounding by smoking a possible association between m(7)Gua excretion and lung cancer supports the importance of methylation of guanine. The finding of an association between m(7)Gua excretion and lung cancer risk mainly among current smokers and subjects with GSTM1 null genotype supports causality in this respect.
    • Proteome characterization of a human urothelial cell line resistant to the bladder carcinogen 4-aminobiphenyl.

      Pastorelli, Roberta; Saletta, Federica; Carpi, Donatella; Campagna, Roberta; dell'Osta, Carlo; Schiarea, Silvia; Vineis, Paolo; Airoldi, Luisa; Matullo, Giuseppe (2007)
      BACKGROUND: The aromatic amine 4-aminobiphenyl (4-ABP) is an environmental and occupational contaminant known to be a major etiological agent of human bladder cancer. 4-ABP metabolites are able to form DNA adducts that may induce mutations and initiate bladder carcinogenesis. Cells exposed to 4-ABP may develop resistance to the carcinogen. The aim of the present study was to detect and identify proteins whose expression is altered in the bladder carcinoma RT112 sub-lines selected for acquired resistance to 4-ABP, in order to disentangle the mechanisms. RESULTS: Differential proteome analysis of cell lysates showed an overall perturbation in cell metabolism and energy pathways in the 4-ABP-resistant human urothelial clones, with over-expression of membrane trafficking proteins such as annexin 2. The resistant clones had altered expression of many proteins linked directly (i.e. lamin A/C, programmed cell death 6 interacting protein) or indirectly (i.e. 94 kDa glucose-regulated protein, fatty acid-binding protein) to decreased apoptosis, suggesting that resistance to 4-ABP might be associated with low apoptotic activity. CONCLUSION: Our data provide evidence that deregulation of apoptosis and membrane trafficking proteins might be strongly implicated in the selection of carcinogen resistant cells. Some of these proteins might have potential as biomarkers of resistance and cancer risk.