Microsomal epoxide hydrolase polymorphisms and lung cancer risk: a quantitative review

To investigate the role of microsomal epoxide hydrolase (mEH) polymorphisms in the aetiology of lung cancer and to assess the interaction between mEH polymorphisms and smoking, we performed a meta-analysis of seven published studies, which included 2078 cases and 3081 controls, and a pooled analysis of eight studies (four published and four unpublished at that time) with a total of 986 cases and 1633 controls. The combined metaanalysis odds ratios (ORs) were 0.98 (95% confidence interval [CI] = 0.72-1.35) for polymorphism at amino acid 113 in exon 3 (His/His versus Tyr/Tyr genotype) and 1.00 (95% CI= 0.71-1.41) for polymorphism at amino acid 139 in exon 4 (Arg/Arg versus His/ His genotype). In the pooled analysis, we observed a significant decrease in lung cancer risk (OR = 0.70, 95% CI = 0.51-0.96) for exon 3 His/His genotype after adjustment for age, sex, smoking and centre. The protective effect of exon 3 polymorphism seems stronger for adenocarcinoma of the lung than for other histological types. The OR for high predicted mEH activity, compared with low activity, was 1.54 (95% CI = 0.77-3.07) in the meta analysis and 1.18 (95% CI = 0.92-1.52) in the pooled analysis. We did not find a consistent modification of the carcinogenic effect of smoking according to mEH polymorphism, although the risk of lung cancer decreased among never smokers with high mEH activity and among heavy smokers with the exon 3 His/His genotype. In conclusion, this study suggests a possible effect of mEH polymorphisms at exon 3 in modulating lung cancer. If present, this effect may vary among different populations, possibly because of interaction with genetic or environmental factors.     

CYP1A1 genetic polymorphisms, tobacco smoking and lung cancer risk in a French Caucasian population

The     

CYP1A1 genetic polymorphisms,tobacco smoking and lung cancer risk in a French Caucasian population

The CYP1A1 gene encoding for an enzyme involved in the metabolic activation of important tobacco carcinogens could be implicated in smoking-induced lung cancer. Given the strong association between tobacco smoking and lung cancer, the effect of tobacco smoke exposure has to be taken into account when studying the potential association between lung cancer and CYP1A1 genotypes. The effect of two CYP1A1 genetic polymorphisms (Mspl and IIe-Val) on lung cancer risk were evaluated using peripheral blood DNA from 150 lung cancer patients and 171 controls. The Mspl sitepresent allele was found among 19.3% of both cases and controls and the variant allele Val among 6.7% of cases and 8.8% of controls. Lung cancer risks associated with the Mspl site-present allele (OR= 0.9; 95%Cl: 0.5-1.8) or with the Val allele (OR= 0.8; 95%Cl: 0.3-1.9) were not increased after adjustment for tobacco and asbestos exposures. These results persisted when analyses were stratified on smoking status, daily consumption of tobacco or duration of smoking. Similar findings were obtained when squamous cell or small cell carcinomas were studied separately. This study thus suggests a minor role for the known CYP1A1 gene polymorphisms in predisposition to lung cancer among Caucasian populations.     

Genetic polymorphisms involved in the inflammatory response and lung cancer risk: A case-control study in Japan

Evidence is accumulating that chronic inflammation may have an important mechanism for the development and progression of lung cancer. Therefore, genetic polymorphisms in genes that involved in the inflammatory response may be associated with lung cancer risk. We evaluated the role of tumor necrosis factor α (TNFA) rs1799724, interleukin 1β (IL1B) rs16944, IL6 rs1800796, myeloperoxidase (MPO) rs2333227 and C-reactive protein (CRP) rs2794520 in a case-control study comprised of 462 lung cancer cases and 379 controls in a Japanese population. Unconditional logistic regression was used to assess the adjusted odds ratios (OR) and 95% confidence intervals (95% CI). CRP rs2794520 (OR = 1.64, 95% CI = 1.19–2.26) and IL6 rs1800796 (OR = 1.41, 95% CI = 1.02–1.96) were associated with lung cancer risk. In addition, we assessed interactions between the polymorphisms and smoking. The polymorphisms did not significantly modify the association between smoking and lung cancer. As TNFA triggers a cytokine cascade, the modifying effect of the TNFA rs1799724 genotypes on the association of any of the remaining polymorphisms with lung cancer risk was also examined. There was a significant interaction between TNFA rs1799724 and MPO rs2333227 (P_interaction = 0.058). Future studies involving larger control and case populations will undoubtedly lead to a more thorough understanding of the role of the polymorphisms involved in the inflammation pathway in lung cancer.     

Polymorphisms in human soluble epoxide hydrolase: effects on enzyme activity, enzyme stability, and quaternary structure

Human soluble epoxide hydrolase (hsEH) has been shown to play a role in regulating blood pressure and inflammation. HsEH consists of an N-terminal phosphatase and a C-terminal epoxide hydrolase domain. In the present study, we examined the effects of polymorphisms in the hsEH gene on phosphatase activity, enzyme stability, and protein quaternary structure. The results showed that mutants Lys55Arg, Arg103Cys, Cys154Tyr, Arg287Gln, and the Arg103Cys/Arg287Gln (double mutant) have significantly lower phosphatase activity compared to the most frequent allele (MFA) of hsEH. In addition, the Lys55Arg, Arg103Cys, Cys154Tyr, Arg287Gln, and the double mutant have significantly lower kcat/Km values. The stabilities at 37 degrees C of purified Arg287Gln and Arg103Cys/Arg287Gln mutants were also significantly reduced compared to the MFA. HPLC size-exclusion studies showed that the MFA exists predominantly as a dimer. However, the Arg287Gln and Arg103Cys/Arg287Gln mutants show increased concentration of the monomer. We conclude that the Arg287Gln polymorphism disrupts putative intra- and inter-monomeric salt-bridges responsible for dimerization.     

Detection of polymorphisms at exons 3 (Tyr113-->His) and 4 (His139-->Arg) of the microsomal epoxide hydrolase gene using fluorescence PCR method combined with melting curves analysis

An association between exon 3 polymorphisms of the gene encoding microsomal epoxide hydrolase (mEH) and susceptibility to the development of chronic obstructive pulmonary disease (COPD) has been described. We have developed two methods for detecting polymorphisms at exons 3 (Tyr113-->His) and 4 (His139-->Arg) of the mEH gene based on different melting temperatures (T(m)) of fluorescent-labeled oligonucleotide hybridization probes using single-step assays that combine fluorescence PCR and melting curve analysis (LightCycler methodology). DNA was extracted from blood in 79 COPD patients and 146 healthy controls. Results were compared with those obtained by restriction fragment length polymorphism (RFLP) analysis to detect Tyr113His variants and a single-strand conformation polymorphism (SSCP) assay for His139Arg detection. The T(m) of the exon 3 polymorphisms were 61.3 degrees C for Tyr113 (wild type) and 67.5 degrees C for His113 (mutant). The T(m) values of the exon 4 polymorphisms were 67.5 degrees C for His139 (wild type) and 59.2 degrees C for Arg139 (mutant). The within- and between-run melting peaks for the same allele differed by less than 0.5 degrees C for both the exon 3 and the exon 4 polymorphisms. Thus, melting analysis allowed easy and unambiguous assignment of genotyping by means of the respective melting curves. The proportion of individuals who were homozygous mutant for exon 3 was significantly higher in the COPD group than in the control group (p=0.004). LightCycler fluorescence genotyping of exon 4 polymorphisms correlated perfectly with SSCP results. RFLP assay classified 2 patients as homozygous mutant while LightCycler analysis genotyped them as heterozygous. DNA analysis by PCR and sequencing confirmed the LightCycler result. These high-speed (about 40 min for 32 samples), highly sensitive, and specific small-volume assays with low labor requirements hold great promise as tools for rapid detection of COPD susceptibility.     

In vitro studies of the influence of glutathione transferases and epoxide hydrolase on the detoxification of acrylamide and glycidamide in blood

Enzymes involved in the metabolism of xenobiotic substances are often polymorphic in humans. Such genetic polymorphisms may result in inter-individual differences in detoxification of certain chemicals, and as a consequence, possibly affect health-risk assessments. This present work concerns studies of the influence of polymorphic enzymes in the detoxification of acrylamide and its metabolite glycidamide. Enzymes that enhance conjugation with glutathione (GSH), the glutathione transferases (GSTs), may influence the detoxification of both acrylamide and glycidamide, whereas the enzyme epoxide hydrolase (EH) should only catalyse the hydrolysis of glycidamide. In this study, the doses of acrylamide or glycidamide measured as specific adducts to hemoglobin (Hb) were analysed in blood samples after in vitro incubation with these compounds. Blood samples from individuals with different genotypes for GSTT1 and GSTM1 were studied. No significant differences in adduct levels depending on genotype were noted. In a parallel experiment, incubation with ethylene oxide was used as positive control. In this experiment individuals carrying GSTT1 showed lower adduct level increments from ethylene oxide than individuals lacking GSTT1. Furthermore, addition of ethacrynic acid or laurylamine, compounds which inhibit GST and EH, respectively, did not affect the adduct levels. These results suggest that neither GSTs nor EH have any significant effect on the blood dose, measured as Hb-adducts over time, after exposure to acrylamide or glycidamide.     

Update on olfactory mucosal metabolic enzymes: age-related changes and N-acetyltransferase activities

We have expanded previous observations on olfactory metabolic enzymes by examining the content of various metabolic enzymes in the olfactory mucosa of the male Long-Evans rat at different ages. Age-related changes in metabolic enzyme content may be related to changes in susceptibility to toxicants with age and may also contribute to altered odorant perception in the elderly. While some enzymes did not vary over the age range examined, decreases in the microsomal content of other enzymes were observed. While mRNA for acetyltransferase enzymes has previously been described in olfactory mucosa, the markedly higher activity of olfactory acetyltransferases compared to liver had not previously been described. Acetyltransferases are important in the metabolism of drugs and toxicants that are aromatic amine derivatives and may contribute to the bioactivation of rodent olfactory mucosal carcinogens such as 2,6-dimethylaniline and alachlor. These studies show that the olfactory mucosa varies in its metabolic capacity with age, and characterize another class of metabolic enzymes in the olfactory mucosa, both of which may impact significantly on responses to toxicants and therapeutic agents in the nasal cavity.     

A novel enantioselective epoxide hydrolase from Agromyces mediolanus ZJB120203: Cloning,characterization and application

A new strain Agromyces mediolanus ZJB120203, capable of enantioselective epoxide hydrolase (EH) activity was isolated employing a newly established colorimetric screening and chiral GC analysis method. The partial nucleotide sequence of an epoxide hydrolase (AmEH) gene from A. mediolanus ZJB120203 was obtained by PCR using degenerate primers designed based on the conserved domains of EHs. Subsequently, an open reading frame containing 1167 bp and encoding 388 amino acids polypeptide were identified. Expression of AmEH was carried out in Escherichia coli and purification was performed by Nickel-affinity chromatography. The purified AmEH had a molecular weight of 43 kDa and showed its optimum pH and temperature at 8.0 and 35 °C, respectively. Moreover, this AmEH showed broad substrates specificity toward epoxides. In this study, it is demonstrated that the AmEH could unusually catalyze the hydrolysis of (R)-ECH to produce enantiopure (S)-ECH. Enantiopure (S)-ECH could be obtained with enantiomeric excess (ee) of >99% and yield of 21.5% from 64 mM (R,S)-ECH. It is indicated that AmEH from A. mediolanus is an attractive biocatalyst for the efficient preparation of optically active ECH.     

Cytochrome P4501A1 and microsomal epoxide hydrolase gene polymorphisms: gene-environment interaction and risk of prostate cancer

The role of low penetrance genes and environmental factors in the etiology of prostate cancer (PCa) is unclear. Most procarcinogens require metabolic activation by CYP4501A1, whereas microsomal epoxide hydrolase (mEH) is involved in the detoxification. In our case-control study, we assessed whether CYP1A1 and mEH susceptibility genotypes, tobacco use, and age factors contribute to PCa risk. One hundred thirty patients with PCa and 140 control subjects were analyzed by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) method from genomic DNA samples. Binary logistic regression model was used for assessing differences in genotype prevalence and their association between patient and the control group. T/C polymorphism of CYP1A1 gene revealed significant association with the tobacco users (p < 0.005) for PCa risk. Our results demonstrated significant association with exon 3 variant genotypes of the mEH alone or in combination with tobacco users (p < 0.005), whereas in exon 4 genotypes, no association was observed. Haplotype analysis projected significant associations with very slow haplotypes of mEH gene (OR = 2.48, 95% CI = 1.41-4.38, p = 0.002). In conclusion, our study demonstrated that exon 3 of mEH and CYP1A1 T/C gene polymorphism are predisposing risk factors for susceptibility of sporadic PCa in northern India. It also suggests that a combination of smoking plays a significant role in modified PCa risk on the study population, which means that smokers carrying susceptible genotypes may be subjected to higher risk than those carrying nonsusceptible genotypes.     

Immobilization of epoxide hydrolase from Aspergillus niger onto DEAE-cellulose: enzymatic properties and application for the enantioselective resolution of a racemic epoxide

Recombinant epoxide hydrolase (EH) from Aspergillus niger can be a very promising tool for the resolution of various racemic epoxides by enantioselective hydrolysis. The enzyme was successfully immobilized by ionic adsorption onto DEAE-cellulose (99% yield, 70% of retention activity). The temperature for maximal activity (40 °C) and the activation energy (38.8 kJ/mol) were similar for both the immobilized and free EHs, whereas the optimal pH was about one unit less for the immobilized enzyme. Thermal stability was also affected by immobilization; the immobilized enzyme appeared to be slightly less stable than the free one. However, a gram-scale resolution of racemic para-chlorostyrene oxide (pCSO) was successfully carried out in a repeated batch reactor, operated for seven cycles. Furthermore, using a very high substrate concentration of 2 M (306 g/L), i.e. biphasic conditions, the resolution of 3 g of pCSO was also achieved in a repeated batch reactor using approximately 300 mg of immobilized EH, corresponding to less than 3 mg of the enzymatic powder.     

Methyl-CpG binding domain 1 gene polymorphisms and lung cancer risk in a Chinese population

Polymorphisms of the methyl-CpG binding domain 1 (MBD1) gene may influence MBD1 activity on gene expression profiles, thereby modulating individual susceptibility to lung cancer. To test this hypothesis, we investigated the associations of four MBD1 polymorphisms and lung cancer risk in a Chinese population. Single locus analysis revealed significant associations between two polymorphisms (rs125555 and rs140689) and lung cancer risk (p=0.011 and p=0.005, respectively). Since the two polymorphisms were in linkage disequilibrium, further haplotype analyses were performed and revealed a significant association with lung cancer (global test p-value=0.0041). Our results suggested that MBD1 polymorphisms might be involved in the development of lung cancer. Validation of these findings in larger studies of other populations is needed.     

Circulating anti-p53 antibodies in lung cancer and relationship to histology and smoking

Anti-p53 antibodies were examined in the plasma of 112 lung cancer patients by ELISA in order to study the distributions in lung cancer patients and the determinants of these antibodies in relation to lung cancer. Twenty (17.9 %) lung cancer patients were found to have anti-p53 antibodies. The distribution of the antibodies by histological type was 7/48 (14.6 %) adenocarcinoma, 8/32 (25.0 %) squamous cell carcinoma, 3/7 (42.9 %) small cell lung cancer, 0/4 large cell carcinoma, 0/8 adenosquamous cell carcinoma and 2/13 (15.4 %) other types. By ethnicity, 8/44 (18.2 %) Caucasians, 4/20 (20.0 %) Hispanics and 8/48 (16.7 %) African-Americans were positive for anti-p53 antibodies, with no significant differences among the groups (p=0.5137). The antibody positivity rates were higher in lung cancer patients 55 years or older (21.2 %) than in the patients under 55 years (7.4 %). The positive rates of the antibodies were 14.3 % in non-smokers, 16.7 % in ex-smokers and 19.1 % in current smokers, with heavy smokers (41 pack-years) having the highest positive rate (28.6 %), but none of these differences were statistically significant (p > 0.05). Seven controls who had anti-p53 antibodies were all ex-smokers or current smokers and some had occupational exposures. No anti-p53 antibodies were found in 41 non-smoking controls. These results suggest that the development of anti-p53 antibodies in pulmonary carcinogenesis and its association with smoking and other carcinogenic exposures deserve further study.     

Polymorphisms in the N acetyltransferase 1 NAT1 gene and lung cancer risk in a minority population

One of the most consistently observed exposure-disease relationship is the one between cigarette smoking and lung cancer. Aromatic amines and their metabolites are found in tobacco smoke and may be a class of carcinogen involved in lung carcinogenesis. T he human N -acetyltransferase 1 ( NAT 1 ) enzyme can activate or deactivate aromatic amines, making it a candidate genetic susceptibility gene. We evaluated the potential role of the NAT 1 gene in lung cancer risk in a hospital-based case-control study in a minority population composed of Mexican- and African-Americans. We also assessed the potential interaction between NAT 1 and other environmental exposures such as cigarette smoking. T here was no overall association between the NAT1*10 genotypes and lung cancer risk. T he adjusted odds ratio for the rapid acetylation genotypes was 0 72 (95 % CI 0 37-1 39) for NAT1 defined as the presence of at least one copy of the NAT1*10 allele when compared with all genotypes without the NAT1*10 allele. Analyses by histological subtype or smoking history did not alter these findings. Other NAT 1 alleles will need to be studied for more conclusive results regarding the relevance of NAT 1 activity to lung carcinogenesis.     

XPA及XPG基因多态性与晚期非小细胞肺癌铂类药物化疗疗效及预后的关系

目的：研究DNA修复基因XPAA23G及XPGC46T位点基因多态性与晚期非小细胞肺癌铂类化疗疗效及预后的关系。方法：经病理学确诊的晚期非小细胞肺癌患者89例,化疗前提取其外周血DNA,用DNA测序技术检测XPA、XPG基因型,所有患者均接受2-4个周期铂类药物为基础的化疗。结果：1）89例患者中,携带XPA23A/A及A/G＋G/G基因型的化疗有效率分别为47.5%和24.5%,差异有统计学意义（x2=5.137,P=0.023）;携带XPG46C/C及C/T＋T/T基因型的患者治疗有效率分别为47.6%、23.4%,二者间也有统计学差异（x2=5.729,P=0.017）,联合分析显示A/A及C/C型化疗有效率最高,达63.0%,而A/A及C/T＋T/T型最低,仅15.4%,四组间有显著统计学差异（x2=14.080,P=0.003）。2）89例患者中位TTP为7个月,XPA23A/A基因型中位TTP为11个月,A/G＋G/G基因型为6个月,两者比较差异有显著性（x2=44.640,P〈0.01）;XPG46C/C基因型中位TTP为10个月,C/T＋T/T基因型为6个月,两者也有统计学差异（x2=32.236,P〈0.01）。联合分析显示,XPAA/A＋XPGC/C型中位TTP最长,达到11个月,而A/G＋G/G及C/T＋T/T基因型最短,仅有4个月,四组间差异有显著统计学意义（x2=59.295,P〈0.01）。结论：XPAA23G及XPGC46T单核苷酸多态性可单独及联合用于预测晚期NSCLC病人对铂类药物的化疗疗效及TTP,初步提示可以根据患者基因型来指导个体化治疗。     

XPA 及XPG 基因多态性与晚期非小细胞肺癌铂类药物化疗疗效及 预后的关系

目的:研究DNA修复基因XPAA23G及XPGC46T位点基因多态性与晚期非小细胞肺癌铂类化疗疗效及预后的关系。方法:经病理学确诊的晚期非小细胞肺癌患者89例,化疗前提取其外周血DNA,用DNA测序技术检测XPA、XPG基因型,所有患者均接受2-4个周期铂类药物为基础的化疗。结果:1)89例患者中,携带XPA23A/A及A/G+G/G基因型的化疗有效率分别为47.5%和24.5%,差异有统计学意义(x2=5.137,P=0.023);携带XPG46C/C及C/T+T/T基因型的患者治疗有效率分别为47.6%、23.4%,二者间也有统计学差异(x2=5.729,P=0.017),联合分析显示A/A及C/C型化疗有效率最高,达63.0%,而A/A及C/T+T/T型最低,仅15.4%,四组间有显著统计学差异(x2=14.080,P=0.003)。2)89例患者中位TTP为7个月,XPA23A/A基因型中位TTP为11个月,A/G+G/G基因型为6个月,两者比较差异有显著性(x2=44.640,P<0.01);XPG46C/C基因型中位TTP为10个月,C/T+T/T基因型为6个月,两者也有统计学差异(x2=32.236,P<0.01)。联合分析显示,XPAA/A+XPGC/C型中位TTP最长,达到11个月,而A/G+G/G及C/T+T/T基因型最短,仅有4个月,四组间差异有显著统计学意义(x2=59.295,P<0.01)。结论:XPAA23G及XPGC46T单核苷酸多态性可单独及联合用于预测晚期NSCLC病人对铂类药物的化疗疗效及TTP,初步提示可以根据患者基因型来指导个体化治疗。     

Association between lung cancer screening and smoking cessation

IntroductionAdults with high-risk smoking histories benefit from annual lung cancer screening. It is unclear if there is an association between lung cancer screening and smoking cessation among U.S. adults who receive screening.MethodsWe performed this population-based cross-sectional study using data from the Behavioral Risk Factor Surveillance System (2017–2020). We defined individuals eligible for lung cancer screening as adults 55–80 years old with ≥ 30 pack-year smoking history who were currently smoking or quit within the last 15 years. We assessed the association between lung cancer screening and current smoking status.ResultsBetween 2017 and 2020, 12,382 participants met screening criteria. Current smoking was reported by 5685 (45.9 %) participants, of whom 40.4 % (2298) reported a cessation attempt in the prior year. Lung cancer screening was reported by only 2022 (16.3 %) eligible participants. Lung cancer screening was associated with lower likelihood of currently smoking (odds ratio [OR] 0.705, 95 % CI 0.626–0.793) compared to individuals who did not receive screening. Screening was also associated with higher likelihood of reporting a cessation attempt in the prior year (OR 1.562, 95 % CI 1.345–1.815) compared to individuals who did not receive screening.ConclusionsReceipt of lung cancer screening was associated with lower smoking rates and more frequent cessation attempts among U.S. adults. Better implementation of lung cancer screening programs is critical and may profoundly increase smoking cessation in this population at risk of developing lung cancer.     

Activation of microsomal epoxide hydrolase by interaction with cytochromes P450: kinetic analysis of the association and substrate-specific activation of epoxide hydrolase function

The kinetics of the association between cytochrome P450 (P450) and microsomal epoxide hydrolase (mEH) was studied by means of resonant mirror based on the principle of surface plasmon resonance. The dissociation equilibrium constants (K(D)) for the affinity of P450 enzymes for mEH were estimated by resonant mirror using an optical biosensor cell covalently bound to rat mEH. Comparable K(D) values were obtained for CYP1A1 and 2B1, and these were greater by one order of magnitude than that for the CYP2C11. To clarify the influences of P450 enzymes on the catalytic activity of mEH, the hydrolyzing activity for styrene oxide and benzo(a)pyrene-7,8-oxide [B(a)P-oxide] was analyzed in the presence or absence of P450s. Styrene oxide hydrolysis was activated by all P450s including the CYP1A, 2B, 2C, and 3A subfamilies. In agreement with the association affinity determined by resonant mirror, CYP2C11 tends to have enhanced activity for styrene oxide hydrolysis. On the other hand, B(a)P-oxide hydrolysis was enhanced by only CYP2C11 while CYP1A1 and CYP2B1 had no effect. These results suggest that (1) many P450 enzymes associate nonspecifically with mEH, (2) the CYP2C11 plays a greater role in the association/activation of mEH and (3) the P450-mediated activation of mEH depends upon the substrate of mEH.