Background. Human genetic polymorphisms in metabolic activation and detoxification pathways are a major source of inter-individual variation in susceptibility to environmentally induced disease. The group has developed genotyping assays for the """"""""at-risk"""""""" variants of enzymes that protect against carcinogens in cigarette smoke, diet, industrial processes and environmental pollution. Following genotyping of over 15,000 individuals for these candidate susceptibility genes, it has been found that the frequency of the at-risk genotypes for glutathione transferase M1 (GSTM1), theta 1 (GSTT1), Pi (GSTP1) and N-acetyltransferase (NAT1 and NAT2), XRCC1, XPD, vary significantly between Asians, European- and African-Americans. This suggests that some of the ethnic differences in cancer incidence may be due to genetic metabolic differences as well as exposure differences. Mission: Our long-term goal is to understanding how genes and environment interact to influence risk of environmentally induced disease. To this end we are engaged in """"""""Environmental Genomics."""""""" This encompasses: 1) identification of candidate environmental response genes, 2) discovery and functional characterization of genetic and phenotypic variation in these genes, and; 3) the analysis in population studies of environmental disease susceptibility associated with functional polymorphisms, acquired susceptibility factors and exposures; and the interactions between these factors. Eventually we hope these genomic approaches will help us to develop assays using genotype, gene expression, and other biomarkers of exposure and effect, that will be predictive of future risk. This information will allow us to more carefully determine the bounds of human variability in risk assessment and will be useful in developing prevention strategies to reduce disease incidence. The Genetic Susceptibility Project takes the candidate susceptibility factors from the laboratory genotype/phenotype studies and tests them in population studies. We are collaborating with numerous NIH, and university-based epidemiology groups to design and carryout appropriate tests of these factors in population-based epidemiology studies. Progress/accomplishments: 1. Glutathione transferases and CYP2E1 metabolize carcinogens that may play a role in the etiology of brain cancer. We evaluated associations between polymorphisms in GSTM1, GSTT1, GSTP I105V, GSTP A114V, CYP2E1 RsaI, and CYP2E1 (Ins96) in 782 patients with brain tumors and 799 controls. The GSTP1 105 Val/Val variant was associated with increased glioma incidence (odds ratio [OR]=1.8, 95% confidence limits [CL]: 1.2, 2.7). The CYP2E1 RsaI variant was weakly associated with the incidence of glioma (OR=1.4, 95% CL: 0.9, 2.4) and acoustic neuroma (OR=2.3, 95% CL: 1.0, 5.3). Previously observed associations between the GSTT1 genotype and glioma incidence were not replicated in this study, but a weak association with meningioma was observed (OR=1.5, 95% CL: 1.0, 2.3). If replicated in other populations, these findings may provide clues to both the genetic and environmental determinants of brain tumors. 2. DNA damage from polycyclic aromatic hydrocarbons (PAH) has been implicated as a risk factor for lung cancer, as have common polymorphisms in the glutathione S-transferase (GST) genes involved in carcinogen detoxification. In this matched case-control study nested within the prospective Physicians Health Study, we evaluated whether biomarkers measured in white blood cells (WBC) significantly predicted risk. Aromatic/hydrophobic-DNA adducts and polymorphisms in GSTM1 and GSTP1 genes were analyzed in 89 cases of primary lung cancer and 173 controls, matched in a 1:2 ratio on smoking, age, and duration of follow up. Among current smokers, adducts were significant predictors of lung cancer risk (after adjusting for GST genotypes, OR=3.10, 95% CI 1.07, 9.01). The combined GSTM1 null / GSTP1 Val genotype was associated with lung cancer overall and especially among former smokers, before and after adjusting for adducts (OR for former smokers = 4.21, CI 1.08, 16.41; adjusted OR=4.68, CI 1.17, 18.71). The findings underscore the complex and important role of biological susceptibility as a determinant of risk from carcinogens found in tobacco smoke and other environmental compounds. 3. Cigarette smoking is the main risk factor for bladder cancer, accounting for at least 50% of bladder cancer in men. Cigarette smoke is a rich source of arylamines, which are detoxified by the NAT2 enzyme and activated by the NAT1 enzyme to highly reactive species that can form bulky adducts on DNA. DNA damage from such adducts is mainly repaired by the nucleotide excision repair pathway, in which the XPD protein functions in opening the DNA helix. We hypothesized that an XPD codon 751 polymorphism (Lys-to-Gln amino acid change) could affect the repair of smoking-induced DNA damage and could be associated with bladder-cancer risk and that NAT genotype could interact with this relationship. The analysis with smoking showed that smokers with the Lys/Lys or Lys/Gln genotypes were twice as likely to have bladder cancer than smokers with the Gln/Gln genotype (test of interaction P = 0.03 We found little evidence for a gene-gene-exposure, three-way interaction among the XPD codon 751 genotype, smoking, and the NAT1/NAT2 genotype. 4. Permanent hair dyes and bladder cancer: risk modification by cytochrome P4501A2 and N-acetyltransferases 1 and 2. Genetic variation in NAT1, NAT2, GSTM1, -T1 and -P1, and cytochrome P 450 1A2 (CYP1A2), can potentially affect the hair dye-bladder cancer relationship due to their participation in the metabolism of arylamines, the putative carcinogenic substances in hair dyes. These genotypes were assessed in 159 (70%) female case patients and 164 (74%) female control subjects who participated in the Los Angeles case-control study. Among NAT2 slow acetylators, permanent hair dye use was associated with a 2.9 fold (95% CI = 1.2, 7.5) increased risk of bladder cancer. Among lifelong nonsmoking women, individuals exhibiting the non-NAT1*10 genotype show a statistically significant increase in bladder cancer risk associated with permanent hair dye use (RR = 6.8, 95% CI = 1.7, 27.4). Frequency- and duration-related dose-response relationships confined to individuals possessing the non-NAT1*10 genotype were positive and statistically significant suggesting that NAT1*10 genotype may protect against hair dye-induced bladder cancer. 5. Smoking, glutathione transferase, markers of inflammatory response. We hypothesize that GST genotypes may modify smoking-induced chronic inflammatory response. A cross-sectional analysis, using a subset of participants in a large (n=15,792) biracial cohort, was used to measure the mean levels of 9 markers of inflammation by different combinations of GST genotypes and smoking status. Smoking greater than 20 pack-years was found to be associated with significant higher levels of ICAM-1, white blood cell count (WBC) , fibrinogen , C-reactive protein (CRP) [Geometric Mean Ratio=1.6 (95%CI 1.0, 2.5)], and lower levels of albumin [D=-0.09g/dl ]. Participants with the GSTM1 null genotype and greater than 20 pack-years of smoking had the highest mean levels of fibrinogen, CRP, ICAM-1, VCAM-1, and von Willebrand factor and lowest mean levels of albumin. The results of this study suggest that GSTM1 and GSTT1 polymorphisms modify the effect of smoking on chronic inflammation. 6. We have followed up our finding linking GST genotypes to smoking-induced cardiovascular disease by examining how GST genotypes modify risk for an early markers of atherosclerosis (corotid intermedial thickness, IMT). IMT determined by B-mode ultrasound in asymptomatic individuals was used as an index of generalized atherosclerosis. We tested 526 cases with mean IMT >0.935 mm and 868 non-cases
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