Epoxide hydrolase--polymorphism and role in toxicology

Targeted Metabolomics Study of Human Plasma Revealed Activation of the Cytochrome P450 Epoxygenase/Epoxide Hydrolase Axis in Patients with IgA Nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis and a leading cause of chronic kidney disease. The pathogenic mechanism of IgAN remains largely unknown and thus a specific therapeutic target is lacking. Here, we reported that the cytochrome P450 (CYP) epoxygenase/epoxide hydrolase (EH) axis was activated in the patients and is likely a therapeutic target for IgAN. Specifically, quantitative profiling of the plasma from IgAN patients and healthy controls revealed significant changes in plasma levels of CYP/EH-mediated lipid epoxides and diols. Subsequently, CYP2C8, CYP2C18, CYP2J2, EPHX1, and EPHX2 were found to be significantly increased in whole blood cells at mRNA levels from the IgAN patients when compared with those of healthy controls. Immunohistochemical analysis showed that all five CYPs and two EHs were upregulated in the kidney tissue from IgAN patients when compared with normative renal tissue, but the expression locations of the proteins were different with most of them. Treatment of HK-2 cells with IgA1 increased cell viability, compressed cell apoptosis, and increased the protein levels of CYP2C9, EPHX1, and EPHX2. All the results agreed that CYPs/EHs axis is likely the prophylactic and therapeutic target for IgAN, providing IgAN patients with a new intervention strategy.

Identification of Phosphorus Stress Related Proteins in the Seedlings of Dongxiang Wild Rice (Oryza Rufipogon Griff.) Using Label-Free Quantitative Proteomic Analysis

Phosphorus (P) deficiency tolerance in rice is a complex character controlled by polygenes. Through proteomics analysis, we could find more low P tolerance related proteins in unique P-deficiency tolerance germplasm Dongxiang wild rice (Oryza Rufipogon, DXWR), which will provide the basis for the research of its regulation mechanism. In this study, a proteomic approach as well as joint analysis with transcriptome data were conducted to identify potential unique low P response genes in DXWR during seedlings. The results showed that 3589 significant differential accumulation proteins were identified between the low P and the normal P treated root samples of DXWR. The degree of change was more than 1.5 times, including 60 up-regulated and 15 downregulated proteins, 24 of which also detected expression changes of more than 1.5-fold in the transcriptome data. Through quantitative trait locus (QTLs) matching analysis, seven genes corresponding to the significantly different expression proteins identified in this study were found to be uncharacterized and distributed in the QTLs interval related to low P tolerance, two of which (LOC_Os12g09620 and LOC_Os03g40670) were detected at both transcriptome and proteome levels. Based on the comprehensive analysis, it was found that DXWR could increase the expression of purple acid phosphatases (PAPs), membrane location of P transporters (PTs), rhizosphere area, and alternative splicing, and it could decrease reactive oxygen species (ROS) activity to deal with low P stress. This study would provide some useful insights in cloning the P-deficiency tolerance genes from wild rice, as well as elucidating the molecular mechanism of low P resistance in DXWR.

Glossary and tutorial of xenobiotic metabolism terms used during small molecule drug discovery and development (IUPAC Technical Report)

This project originated more than 15 years ago with the intent to produce a glossary of drug metabolism terms having definitions especially applicable for use by practicing medicinal chemists. A first-draft version underwent extensive beta-testing that, fortuitously, engaged international audiences in a wide range of disciplines involved in drug discovery and development. It became clear that the inclusion of information to enhance discussions among this mix of participants would be even more valuable. The present version retains a chemical structure theme while expanding tutorial comments that aim to bridge the various perspectives that may arise during interdisciplinary communications about a given term. This glossary is intended to be educational for early stage researchers, as well as useful for investigators at various levels who participate on today’s highly multidisciplinary, collaborative small molecule drug discovery teams.

Protein kinase Cδ mediates methamphetamine-induced dopaminergic neurotoxicity in mice via activation of microsomal epoxide hydrolase

We previously demonstrated that activation of protein kinase Cδ (PKCδ) is critical for methamphetamine (MA)-induced dopaminergic toxicity. It was recognized that microsomal epoxide hydrolase (mEH) also induces dopaminergic neurotoxicity. It was demonstrated that inhibition of PKC modulates the expression of mEH. We investigated whether MA-induced PKCδ activation requires mEH induction in mice. MA treatment (8 mg/kg, i.p., × 4; 2 h interval) significantly enhanced the level of phosphorylated PKCδ in the striatum of wild type (WT) mice. Subsequently, treatment with MA resulted in significant increases in the expression of cleaved PKCδ and mEH. Treatment with MA resulted in enhanced interaction between PKCδ and mEH. PKCδ knockout mice exhibited significant attenuation of the enhanced mEH expression induced by MA. MA-induced hyperthermia, oxidative stress, proapoptotic potentials, and dopaminergic impairments were attenuated by PKCδ knockout or mEH knockout in mice. However, treating mEH knockout in mice with PKCδ inhibitor, rottlerin did not show any additive beneficial effects, indicating that mEH is a critical mediator of neurotoxic potential of PKCδ. Our results suggest that MA-induced PKCδ activation requires mEH induction as a downstream signaling pathway and that the modulation of the PKCδ and mEH interaction is important for the pharmacological intervention against MA-induced dopaminergic neurotoxicity.

Association of Activity Altering Genotypes - Tyr113His and His139Arg in Microsomal Epoxide Hydrolase Enzyme with Esophageal Squamous Cell Carcinoma

The study aimed to explore the relationship of microsomal epoxide hydrolase (mEH) exon 3 (Tyr113His) and exon 4 (His139Arg) polymorphisms and predicted mEH activity with esophageal squamous cell carcinoma (ESCC) risk. 482 histologically confirmed cases and equal number of matched controls were analyzed by polymerase chain reaction-restriction length polymorphism (PCR-RFLP). Conditional logistic regression models were used to examine the association of polymorphisms with ESCC. We noted exon 3 slow genotype (OR = 6.57; CI 3.43-12.57) as well as predicted low mEH activity (OR = 3.99; CI 2.32-6.85) was associated with the ESCC risk. Elevated ESCC risk estimates were seen in smokers independent of genotypes but the association was stronger among smokers with exon 3 variant (OR = 6.67; 3.29-13.53) and low activity (OR = 7.52; CI 3.46-16.37) genotypes. Positive family history of cancer synergistically increased ESCC risk in the individuals who harbored exon 3 (OR = 13.59; CI 5.63-32.81) or altered mEH activity genotypes (OR = 13.35; CI 5.10-34.94). Significant interaction was seen between mEH exon 3 and exon 4 genotypes (P = 0.006) and between predicted mEH activity and positive family history of cancer (P = 0.018). These findings suggest association of ESCC risk with mEH polymorphisms which get modified by tobacco smoking and positive family history of cancer.

Maternal Smoking during Early Pregnancy, GSTP1 and EPHX1 Variants, and Risk of Isolated Orofacial Clefts

Objective:

To examine the interactions between four fetal xenobiotic metabolizing gene polymorphisms, maternal cigarette smoking, and risk for oral cleft defects.

Design and Participants:

California population–based case-control study of 431 infants born with isolated orofacial clefts and 299 nonmalformed controls.

Main Outcome Measures:

Infants were genotyped for functional polymorphisms of the detoxification enzymes microsomal epoxide hydrolase-1 (EPHX1 T→C [Tyr113His], and A→G [His139Arg]), and glutathione-S transferase Pi-1 (GSTP1 A→G [Ile105Val] and C→T [Ala114Val]), and risks for cleft outcomes were measured for gene only and gene-maternal smoking effects.

Results:

Although smoking was associated with an increased risk for isolated cleft lip ± palate, we found no independent associations of genotypes of EPHX1-codon 113 or GSTP1-codon 105 polymorphisms for either isolated cleft lip ± palate or isolated cleft palate. The heterozygote genotype for the EPHX1-codon 139 polymorphism was associated with an increased risk of isolated cleft palate (odds ratio = 1.6 [95% confidence interval, 1.0 to 2.6]). Infant EPHX1 and GTSP1 polymorphic variants did not appreciably alter the risks for clefts associated with maternal smoking, nor were any EPHX1 combined genotype-specific risks found. Infant genotypes of the GSTP1-codon 105 polymorphism, combined with glutathione-S-transferase-μ-1 null genotypes, did not appreciably alter the risk of orofacial clefts.

Conclusions:

Our results suggest that genetic variation of the detoxification enzymes EPHX1 and GSTP1 did not increase the risks of orofacial clefting, nor do they influence the risks associated with maternal smoking.

Oxidative Stress and Genetic Variants of Xenobiotic-Metabolising Enzymes Associated with COPD Development and Severity in Serbian Adults

The genetic and non-genetic factors that contribute to the development of chronic obstructive pulmonary disease (COPD) are still poorly understood. We investigated the potential role of genetic variants of xenobiotic-metabolising enzymes (glutathione-S-transferase M1, GSTM1; glutathione-S-transferase T1, GSTT1; microsomal epoxide hydrolase, mEH), oxidative stress (assessed by urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine, 8-oxodG/creatinine), sex, ageing and smoking habits on susceptibility to development of COPD and its severity in Serbian population. The investigated population consisted of 153 healthy subjects (85 males and 68 females) and 71 patients with COPD (33 males and 38 females). Detection of GSTM1*null, GSTT1*null, mEH Tyr113His and mEH His139Arg gene variants was performed by PCR/RFLP method. Urinary 8-oxodG was determined using HPLC-MS/MS, and expressed as 8-oxodG/creatinine. We revealed that increased urinary 8-oxodG/creatinine and leucocytosis are the strongest independent predictors for COPD development. Increased level of oxidative stress increased the risk for COPD in males [odds ratio (OR), 95% confidence interval (CI): 8.42, 2.26-31.28], more than in females (OR, 95% CI: 3.60, 1.37-9.45). Additionally, independent predictors for COPD were ageing in males (OR, 95% CI: 1.29, 1.12-1.48), while in females they were at least one GSTM1 or GSTT1 gene deletion in combination (OR, 95% CI: 23.67, 2.62-213.46), and increased cumulative cigarette consumption (OR, 95% CI: 1.09, 1.01-1.16). Severity of COPD was associated with the combined effect of low mEH activity phenotype, high level of oxidative stress and heavy smoking. In conclusion, early identification of GSTM1*null or GSTT1*null genotypes in females, low mEH activity phenotype in heavy smokers and monitoring of oxidative stress level can be useful diagnostic and prognostic biomarkers.

Genetic enhancement of microsomal epoxide hydrolase improves metabolic detoxification but impairs cerebral blood flow regulation

Microsomal epoxide hydrolase (mEH) is a detoxifying enzyme for xenobiotic compounds. Enzymatic activity of mEH can be greatly increased by a point mutation, leading to an E404D amino acid exchange in its catalytic triad. Surprisingly, this variant is not found in any vertebrate species, despite the obvious advantage of accelerated detoxification. We hypothesized that this evolutionary avoidance is due to the fact that the mEH plays a dualistic role in detoxification and control of endogenous vascular signaling molecules. To test this, we generated mEH E404D mice and assessed them for detoxification capacity and vascular dynamics. In liver microsomes from these mice, turnover of the xenobiotic compound phenanthrene-9,10-oxide was four times faster compared to WT liver microsomes, confirming accelerated detoxification. mEH E404D animals also showed faster metabolization of a specific class of endogenous eicosanoids, arachidonic acid-derived epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs). Significantly higher DHETs/EETs ratios were found in mEH E404D liver, urine, plasma, brain and cerebral endothelial cells compared to WT controls, suggesting a broad impact of the mEH mutant on endogenous EETs metabolism. Because EETs are strong vasodilators in cerebral vasculature, hemodynamics were assessed in mEH E404D and WT cerebral cortex and hippocampus using cerebral blood volume (CBV)-based functional magnetic resonance imaging (fMRI). Basal CBV₀ levels were similar between mEH E404D and control mice in both brain areas. But vascular reactivity and vasodilation in response to the vasodilatory drug acetazolamide were reduced in mEH E404D forebrain compared to WT controls by factor 3 and 2.6, respectively. These results demonstrate a critical role for mEH E404D in vasodynamics and suggest that deregulation of endogenous signaling pathways is the undesirable gain of function associated with the E404D variant.

Biomarkers of susceptibility following benzene exposure: influence of genetic polymorphisms on benzene metabolism and health effects

Benzene is a ubiquitous occupational and environmental pollutant. Improved industrial hygiene allowed airborne concentrations close to the environmental context (1-1000 µg/m(3)). Conversely, new limits for benzene levels in urban air were set (5 µg/m(3)). The biomonitoring of exposure to such low benzene concentrations are performed measuring specific and sensitive biomarkers such as S-phenylmercapturic acid, trans, trans-muconic acid and urinary benzene: many studies referred high variability in the levels of these biomarkers, suggesting the involvement of polymorphic metabolic genes in the individual susceptibility to benzene toxicity. We reviewed the influence of metabolic polymorphisms on the biomarkers levels of benzene exposure and effect, in order to understand the real impact of benzene exposure on subjects with increased susceptibility.

Biomarkers of tobacco smoke exposure

Diseases and death caused by exposure to tobacco smoke have become the single most serious preventable public health concern. Thus, biomarkers that can monitor tobacco exposure and health effects can play a critical role in tobacco product regulation and public health policy. Biomarkers of exposure to tobacco toxicants are well established and have been used in population studies to establish public policy regarding exposure to second-hand smoke, an example being the nicotine metabolite cotinine, which can be measured in urine. Biomarkers of biological response to tobacco smoking range from those indicative of inflammation to mRNA and microRNA patterns related to tobacco use and/or disease state. Biomarkers identifying individuals with an increased risk for a pathological response to tobacco have also been described. The challenge for any novel technology or biomarker is its translation to clinical and/or regulatory application, a process that requires first technical validation of the assay and then careful consideration of the context the biomarker assay may be used in the regulatory setting. Nonetheless, the current efforts to investigate new biomarker of tobacco smoke exposure promise to offer powerful new tools in addressing the health hazards of tobacco product use. This review will examine such biomarkers, albeit with a focus on those related to cigarette smoking.

Metabolic polymorphisms and biomarkers of effect in the biomonitoring of occupational exposure to low-levels of benzene: state of the art

Current levels of occupational exposure to benzene, a genotoxic human carcinogen, in Western countries are reduced by two-three orders of magnitude (from ppm to ppb) as compared to the past. However, as benzene toxicity is strongly dependent on biotransformation and recent evidence underlines a higher efficiency of bio-activation pathways at lower levels of exposure, toxic effects at low doses could be higher than expected, particularly in susceptible individuals. Currently, biological monitoring can allow accurate exposure assessment, relying on sensitive and specific enough biomarkers of internal dose. The availability of similarly reliable biomarkers of early effect or susceptibility could greatly improve the risk assessment process to such an extent that risk could even be assessed at the individual level. As to susceptibility biomarkers, functional genetic polymorphisms of relevant biotransformation enzymes may modulate the risk of adverse effects (NQO1) and the levels of biomarkers of internal dose, in particular S-phenylmercapturic acid (GSTM1, GSTT1, GSTA1). Among biomarkers of early effect, genotoxicity indicators, although sensitive in some cases, are too aspecific for routine use in occupational health surveillance programmes. Currently only the periodical blood cell count seems suitable enough to be applied in the longitudinal monitoring of effects from benzene exposure. Novel biomarkers of early effect are expected from higher collaboration among toxicologists and clinicians, also using advanced "omics" techniques.

Is there a role for MDR1, EPHX1 and protein Z gene variants in modulation of warfarin dosage? a study on a cohort of the Egyptian population

BACKGROUND

There is considerable inter-individual variability in warfarin dosages necessary to achieve target therapeutic anticoagulation. Polymorphisms in genes, which master warfarin pharmacokinetics and pharmacodynamics, might influence warfarin dose variation. Genes encoding drug transporters, such as human multidrug resistance (MDR1), as well as epoxide hydrolase 1 (EPHX1), which is a putative subunit of the vitamin K epoxide reductase, and Protein Z (PZ), which is a vitamin K-dependent plasma glycoprotein, are among those candidate genes.

OBJECTIVE

The purpose of this study was to investigate the contribution of MDR1 C3435T, EPHX1 H139R and PZ A-13G gene polymorphisms in warfarin dose variation in a cohort of the Egyptian population.

METHODS

Eighty-four patients whose international normalized ratio (INR) was in the range of 2-3, 41 males and 43 females, with a mean (±SD) age of 40.9 (13.3) years were recruited into this study. MDR1 C3435T, EPHX1 H139R and PZ A-13G gene polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism. Primarily, linear regression analysis, including the variables age, gender, MDR1 C3435T, EPHX1 H139R and combined MDR1 C3435T, EPHX1 H139R and PZ A-13G genotypes, was used to assess the effective factors for warfarin maintenance dose. Secondly, the previously examined cytochrome P450 (CYP) 2C9 A1075C and vitamin K epoxide reductase complex subunit 1 (VKORC1) C1173T were added to the regression analysis.

RESULTS

Warfarin dose/week was not influenced by each of the MDR1 C3435T, EPHX1 H139R, and PZ A-13G gene polymorphisms when examined separately. However, when these single nucleotide polymorphisms (SNPs) were combined, MDR1 TT/EPHX1 RH,RR/PZ AA subjects showed statistically significant increase in warfarin dose/week when compared with MDR1 CC/EPHX1 RH,RR/PZ AA subjects [median (25th-75th percentiles): 49.0 (42.0-59.5) vs. 35.0 (24.5-42.0) mg/week, respectively] (p = 0.014). In contrast, in the presence of wild-type EPHX1 HH, there was a decrease in warfarin dose/week in MDR1 TT subjects when compared with CT and CC subjects [median (25th-75th percentiles): 22.0 (17.5-30.6), 42.0 (35.0-49.0) and 42.0 (28.0-54.3) mg/week, respectively] (p = 0.005 and 0.030, respectively). Age had a significant contribution (p = 0.048) to the overall variability in warfarin dose. Calculated weekly dose = 52.928 - (0.289 × age) + (9.709 × combined genotype). The multivariate linear regression equation of warfarin maintenance dose accounted for about 8 % of variation in dose (R (2) = 0.079), age accounted for 5 % of variation, while combined genotypes added the extra 3 %. However, the new regression equation accounted for 20.9 % of variation in dose. Age accounted for 5 %, while VKORC1 C1173T accounted for an extra 13 % of variation and MDR1 C3435T accounted for the remaining 3 % of variation. Calculated dose = 64.909 - (0.282 × age) - (13.390 × VKORC1) - (7.164 × MDR1). Correlation analysis showed a close and significant relationship between the calculated and actual warfarin dose (r = 0.457; p < 0.0005).

CONCLUSION

Warfarin dose/week was significantly influenced by the combined MDR1 C3435T and EPHX1 H139R gene polymorphism since no polymorphism of PZ A-13G SNP was detected in our studied Egyptian population. Future studies with larger sample size will be needed to confirm our findings before definitive conclusions can be made.

Benzo pyrene-induced DNA adducts and gene expression profiles in target and non-target organs for carcinogenesis in mice

BACKGROUND

Gene expression changes induced by carcinogens may identify differences in molecular function between target and non-target organs. Target organs for benzo[a]pyrene (BaP) carcinogenicity in mice (lung, spleen and forestomach) and three non-target organs (liver, colon and glandular stomach) were investigated for DNA adducts by 32P-postlabelling, for gene expression changes by cDNA microarray and for miRNA expression changes by miRNA microarray after exposure of animals to BaP.

RESULTS

BaP-DNA adduct formation occurred in all six organs at levels that did not distinguish between target and non-target. cDNA microarray analysis showed a variety of genes modulated significantly by BaP in the six organs and the overall gene expression patterns were tissue specific. Gene ontology analysis also revealed that BaP-induced bioactivities were tissue specific; eight genes (Tubb5, Fos, Cdh1, Cyp1a1, Apc, Myc, Ctnnb1 and Cav) showed significant expression difference between three target and three non-target organs. Additionally, several gene expression changes, such as in Trp53 activation and Stat3 activity suggested some similarities in molecular mechanisms in two target organs (lung and spleen), which were not found in the other four organs. Changes in miRNA expression were generally tissue specific, involving, in total, 21/54 miRNAs significantly up- or down-regulated.

CONCLUSIONS

Altogether, these findings showed that DNA adduct levels and early gene expression changes did not fully distinguish target from non-target organs. However, mechanisms related to early changes in p53, Stat3 and Wnt/β-catenin pathways may play roles in defining BaP organotropism.

Investigation of the Association between Genetic Polymorphism of Microsomal Epoxide Hydrolase and Primary Brain Tumor Incidence

mEH is a critical biotransformation enzyme that catalyzes the conversion of xenobiotic epoxide substrates into more polar diol metabolites: it is also capable of inactivating a large number of structurally different molecules. Two polymorphisms affecting enzyme activity have been described in the exon 3 and 4 of the mEH gene. The hypothesis of this study is that inherent genetic susceptibility to a primary brain tumor is associated with mEH gene polymorphisms. The polymorphisms of the mEH gene were determined with PCR-RFLP techniques and 255 Turkish individuals. Our results indicate that the frequency of the mEH exon 4 polymorphism (in controls) is significantly higher than that of primary brain tumor patients (OR = 1.8, 95% CI = 1.0–3.4). This report, however, failed to demonstrate a significant association between mEH exon 3 polymorphism and primary brain tumor susceptibility in this population. Analysis of patients by both histological types of primary brain tumor and gene variants showed no association, although analysis of family history of cancer between cases and controls showed a statistically significant association (χ² = 7.0, P = 0.01). Our results marginally support the hypothesis that genetic susceptibility to brain tumors may be associated with mEPHX gene polymorphisms.

Sp1 and Sp3 transcription factors regulate the basal expression of human microsomal epoxide hydrolase (EPHX1) through interaction with the E1b far upstream promoter

Microsomal epoxide hydrolase (mEH, EPHX1) is a critical biotransformation enzyme, catalyzing the metabolism of many xenobiotics. Human mEH is transcribed using alternative promoters. The upstream E1 promoter is active in liver while the far upstream E1b promoter drives the expression of mEH in all tissues, including liver. Although several liver-specific transcription factors have been identified in the regulation of E1 transcription, little is known regarding the mechanisms of E1b transcriptional regulation. Genome-wide mapping of DNase I hypersensitive sites revealed an open chromatin region between nucleotide -300 upstream and +400 downstream of E1b. This area coincides with a previously described promoter region responsible for maintaining high basal promoter activity. In silico analysis of this location revealed several Sp1/Sp3 binding sites. Site-directed mutagenesis of these motifs suppressed the transactivation activity of the E1b proximal promoter, indicating their importance as contributors to E1b promoter regulation. Further, E1b promoter activities were increased significantly following Sp1 and Sp3 overexpression, while Mithramycin A, a selective Sp1 inhibitor, reduced the promoter activities. EMSA studies demonstrated that Sp1 bound to two putative Sp1/Sp3 binding sites. ChIP analysis confirmed that both endogenous Sp1 and Sp3 were bound to the proximal promoter region of E1b. Knockdown of Sp1 expression using siRNA did not alter the endogenous E1b transcriptional level, while knockdown of Sp3 greatly decreased E1b expression in different human cell lines. Taken together, these results support the concept that Sp1 and Sp3 are functionally involved as transcriptional integrators regulating the basal expression of the derived mEH E1b variant transcript.

eNOSI4 and EPHX1 polymorphisms affect maternal susceptibility to preeclampsia: analysis of five polymorphisms predisposing to cardiovascular disease in 279 Caucasian and 241 African women

PURPOSE

The aim of this study was to evaluate possible associations of genetic polymorphisms predisposing to cardiovascular disease with the development and/or the severity of preeclampsia.

METHODS

A two hospital-based prospective case-control study was performed in Germany and Ghana. 470 blood samples of 250 Caucasian and 220 black African have been genotyped by pyrosequencing and fragment length analysis. We evaluated the distribution of the epoxide hydrolase 1 (EPHX1) polymorphism on exon 3, the endothelial nitric oxide synthase (eNOS) polymorphisms on exon 7 and on intron 4, the angiotensinogen polymorphism on exon 2 and the estrogen receptor 1 polymorphism in intron 1.

RESULTS

74 Caucasian and 84 African were classified as preeclampsia with 27 Caucasian developing a hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome and 17 African women experiencing eclampsia. Multivariate logistic regression analysis adjusting for ethnicity, age and parity revealed for carriers of eNOSI4 VNTR4a a 1.7-fold increased (95% CI 1.10-2.711, p = 0.016) risk to develop preeclampsia and a 3.6-fold increase for carriers of the EPHX1 113Tyr (95% CI 1.366-8.750, p = 0.009) to develop severest preeclampsia.

CONCLUSION

Our finding of eNOSI4 polymorphism predisposing to preeclampsia independently of ethnicity, age and parity supports the concept of NO being involved in the endothelial disorder preeclampsia. Since EPHX1 is highly expressed in the liver, can interact with various signaling pathways and is involved in central nervous system disorders, the association of EPHX1 polymorphism with the HELLP syndrome and eclampsia may hint to EPHX being a further key player in the pathogenesis of preeclampsia.

Influence of genetic polymorphisms on biomarkers of exposure and effects in children living in Upper Silesia

This article is a follow-up to our previous molecular epidemiology studies on the DNA damage in children from the Upper Silesia region of Poland. It is expected that metabolic and DNA repair gene polymorphisms may modulate individual susceptibility to environmental exposure. In this study, we investigate the association between polymorphisms of metabolising (CYP2D, EPHX1, GSTM1, GSTP1, GSTT1, NAT2) and DNA repair (XPD, XRCC1, XRCC3) genes and selected biomarkers of exposure and effect such as levels of 1-hydroxypyrene (1-OHP) and urinary mutagenicity, aromatic DNA adducts, sister chromatid exchange (SCE) and micronuclei (MN) in 74 children. Both 1-OHP concentration and urinary mutagenicity tested by TA98+S9 were significantly higher in individuals with EPHX1 (exon 4) Arg/Arg genotype than in individuals with other genotype. The EPHX1 (exon 3) significantly affected urinary mutagenicity tested with strain YG1024+S9. The urinary mutagenicity in individuals with Tyr/Tyr homozygotes was lower than in individuals with Tyr/His and His/His (1057±685 vs. 1432±1003 revertants/mol creatinine). XRCC3 Met/Met genotype was associated with significantly higher levels of 1-OHP in urine compared with only The/Met genotype. The PAH-DNA adduct levels in the subgroup with GSTM1 null genotype was 2-fold higher than in individuals with GSTM1 active (7.06±5.12 vs. 13.14±9.81 adduct/10(8) nucleotides). The mean level of aromatic DNA adducts in children with deletion of the GSTT1 gene was significantly higher compared with individuals with that gene present (8.03±6.23 vs. 14.66±10.70 adduct/10(8) nucleotides). Also the carriers of the XPD Lys/Lys genotype showed higher levels of DNA adducts than heterozygotes (13.16±9.70 vs. 6.81±5.86 adducts/10(8) nucleotides). Children carrying the XRCC3-241 Met/Met genotype exhibited a higher number of SCE in peripheral blood lymphocytes than carriers of Thr/Met allele (8.15±0.86 vs. 7.62±0.79 SCE/cell). It was also observed that children with the GSTP1 slow conjugator had significantly elevated MN in peripheral blood lymphocytes compared with fast conjugator (4.23±3.49 vs. 6.56±5.00 MN/1000 cells).

Association of microsomal epoxide hydrolase exon 3 Tyr113His and exon 4 His139Arg polymorphisms with gastric cancer in India

BACKGROUND

Microsomal epoxide hydrolase, an important phase II xenobiotic enzyme, exhibits polymorphisms at exon 3 (Tyr113His [T/C]) and exon 4 (His139Arg [A/G]), which modulate enzyme activity; this may affect susceptibility to cancers. We studied association between these polymorphisms and gastric cancer (GC).

METHODS

In a prospective study, 77 patients with GC, 50 with peptic ulcer, and 160 healthy controls (HC) were genotyped for exon 3 (PCR-RFLP followed by sequencing) and exon 4 (PCR-RFLP). Helicobacter pylori was considered to be present if two of three tests (histology, rapid urease test, and IgG antibody) were positive.

RESULTS

Tyr113His and His139Arg genotypes and haplotypes were comparable among groups. 113His carriers were commoner among H. pylori-negative patients with GC than HC (p-value = 0.019, odds ratio (OR) = 2.5, 95 % confidence interval (CI) = 1.2-5.4). Haplotype combination of exons 3 and 4 113Tyr-139Arg (TA) were associated with higher and reduced risk in patients with GC than HC in presence and absence of H. pylori (25 % vs. 11 %; p-value = 0.033, OR = 2.61, 95 % CI = 1.08-6.3 and 11.6 % vs. 28.7 %; p-value = 0.004, OR = 0.33, 95 % CI = 0.15-0.7, respectively).

CONCLUSIONS

Though 113Tyr-139Arg was associated with GC in presence of H. pylori, in its absence, it appeared to be protective. Exon 3, 113His, however, was associated with GC even in absence of H. pylori infection.

Cytotoxicity and anti-inflammatory activity of methylsulfanyl-triazoloquinazolines

A series of twenty five 2-methylsulfanyl-[1,2,4]triazolo[1,5-a]quinazoline derivatives 1-25 was previously synthesized. We have now investigated their cytotoxic effects against hepatocellular Hep-G2 and colon HCT-116 carcinoma cells and effect on the macrophage growth, in addition to their influence of the inflammatory mediators [nitric oxide (NO), tumor necrosis factor-α (TNF-α), prostaglandin E-2 (PGE-2) and in bacterial lipopolysachharide (LPS)-stimulated macrophages]. The findings revealed that compounds 13 and 17 showed the highest cytotoxicity and that 3, 6-8 and 25 are promising multi-potent anti-inflammatory agents.

Systematic review and meta-analysis of the relationship between EPHX1 polymorphisms and colorectal cancer risk

BACKGROUND

Microsomal epoxide hydrolase (EPHX1) plays an important role in both the activation and detoxification of PAHs, which are carcinogens found in cooked meat and tobacco smoking. Polymorphisms at exons 3 and 4 of the EPHX1 gene have been reported to be associated with variations in EPHX1 activity. The aim of this study is to quantitatively summarize the relationship between EPHX1 polymorphisms and colorectal cancer (CRC) risk.

METHODS

Two investigators independently searched the Medline, Embase, CNKI, and Chinese Biomedicine Databases for studies published before June 2012. Summary odds ratios (ORs) and 95% confidence intervals (CIs) for EPHX1 Tyr113His (rs1051740) and His139Arg (rs2234922) polymorphisms and CRC were calculated in a fixed-effects model and a random-effects model when appropriate.

RESULTS

This meta-analysis yielded 14 case-control studies, which included 13 studies for Tyr113His (6395 cases and 7893 controls) and 13 studies for His139Arg polymorphisms (5375 cases and 6962 controls). Overall, the pooled results indicated that EPHX1 Tyr113His polymorphism was not associated with CRC risk; while the His139Arg polymorphism was significantly associated with decreased CRC risk (Arg/His vs. His/His, OR = 0.90, 95%CI = 0.83-0.98; dominant model, OR = 0.92, 95%CI = 0.85-0.99). The statistically significant association between EPHX1 His139Arg polymorphism and CRC was observed among Caucasians and population-based case-control studies. This association showed little heterogeneity and remained consistently strong when analyses were limited to studies in which genotype frequencies were in Hardy-Weinberg equilibrium, or limited to studies with matched controls. When cumulative meta-analyses of the two associations were conducted by studies' publication time, the results were persistent and robust.

CONCLUSION

This meta-analysis suggests that EPHX1 Tyr113His polymorphism may be not associated with CRC development; while the EPHX1 His139Arg polymorphism may have a potential protective effect on CRC.

System review and metaanalysis of the relationships between five metabolic gene polymorphisms and colorectal adenoma risk

The relationships between some metabolic (including EPHX1, GSTs and NQO1) gene polymorphisms and colorectal adenoma (CRA) risk have been commonly studied, and no conclusions are available up to now. Therefore, we quantitatively studied the relationships by a metaanalysis. The databases of Medline and Embase were retrieved updated to June 15th, 2011. Crude or adjusted odds ratio (crude OR or adjusted OR) and 95% confidence interval (95%CI) were calculated to present the strength of the associations. Overall, nine case-control studies for EPHX1 Tyr113His and His139Arg, five case-control studies for GSTM1, four studies for GSTP1 Ile105Val, two studies for GSTP1 Ala114Val, six studies for GSTT1 and four studies for NQO1 Pro187Ser were included in this metaanalysis. The results of combined analyses indicated that EPHX1 Tyr113His and His139Arg, GSTT1, GSTM1, GSTP1 Ile105Val and Ala114Val were not associated with CRA risk [crude OR (95%CI): 0.98 (0.90-1.07) and P ( z-test) = 0.65 for EPHX1 His carriers vs. Tyr/Tyr; 1.05 (0.97-1.15) and P ( z-test) = 0.21 for EPHX1 Arg carriers vs. His/His; 1.05 (0.92-1.20) and P ( z-test) = 0.47 for GSTT1 Null vs. Present; 1.01 (0.90-1.13) and P ( z-test) = 0.90 for GSTM1 Null vs. Present; 1.04 (0.92-1.17) and P ( z-test) = 0.56 for G carriers vs. AA for GSTP1 Ile105Val; 0.88 (0.70-1.11) and P ( z-test) = 0.28 for T carriers vs. CC for GSTP1 Ala114Val]. In contrast, Ser allele of NQO1 Ser187Pro might be a modest risk factor for CRA development [1.19 (1.06-1.33) and P ( z-test) = 0.003 for Ser carriers vs. Pro/Pro]. To get more precise evidences, adjusted ORs (95%CI) for EPHX1 Tyr113His, His139Arg, GSTP1 Ile105Val and NQO1 Ser187Pro were also calculated based on adjusted ORs (95%CIs) reported in primary studies. The results still indicated that EPHX1 Tyr113His, His139Arg and GSTP1 Ile105Val were not associated with CRA risk except for NQO1 Ser187Pro. When subgroup analyses were performed for population-based case-control studies or studies in HWE for EPHX1 Tyr113His and His139Arg, and NQO1 Ser187Pro polymorphisms, the results were persistent. Although with modest limitations and biases, this metaanalysis suggests that EPHX1 Tyr113His and His139Arg, GSTT1, GSTM1, GSTP1 Ile105Val and Ala114Val polymorphisms may be not risk factors for CRA development, while Ser allele of NQO1 Ser187 Pro may be a modest risk factor for CRA development, and may be used with other genetic markers for screening CRA in the future.

Update in chronic obstructive pulmonary disease: role of antioxidant and metabolizing gene polymorphisms

Chronic obstructive pulmonary disease (COPD) is characterized by systemic and local chronic inflammation and oxidative stress. The sources of the increased oxidative stress in COPD patients derive from the increased burden of inhaled oxidants such as cigarette smoke and other forms of particulate or gaseous air pollution and from the increase in reactive oxygen species (ROS) generated by several inflammatory, immune, and structural airways cells. There is increasing evidence that genetic factors may also contribute to the pathogenesis if COPD, particularly antioxidant genes, which may confer a susceptibility to environmental insults such as cigarette smoke and thereafter development of COPD. Consequently, heme oxygenase-1 (HO-1), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), microsomal epoxide hydrolase (EPHX1), and cytochrome P450 (CYP) genetic polymorphisms may have an important role in COPD pathogenesis. In this review the authors summarized the most recent findings dealing with these antioxidant genes contributing to the free radical neutralization and xenobiotic enzymes playing a role in different phases of cell detoxification reactions related to the redox status imbalance in COPD, with an emphasis on their possible roles in disease progression.

Genetic polymorphism in metabolism and host defense enzymes: implications for human health risk assessment

Genetic polymorphisms in xenobiotic metabolizing enzymes can have profound influence on enzyme function, with implications for chemical clearance and internal dose. The effects of polymorphisms have been evaluated for certain therapeutic drugs but there has been relatively little investigation with environmental toxicants. Polymorphisms can also affect the function of host defense mechanisms and thus modify the pharmacodynamic response. This review and analysis explores the feasibility of using polymorphism data in human health risk assessment for four enzymes, two involved in conjugation (uridine diphosphoglucuronosyltransferases [UGTs], sulfotransferases [SULTs]), and two involved in detoxification (microsomal epoxide hydrolase [EPHX1], NADPH quinone oxidoreductase I [NQO1]). This set of evaluations complements our previous analyses with oxidative and conjugating enzymes. Of the numerous UGT and SULT enzymes, the greatest likelihood for polymorphism effect on conjugation function are for SULT1A1 (*2 polymorphism), UGT1A1 (*6, *7, *28 polymorphisms), UGT1A7 (*3 polymorphism), UGT2B15 (*2 polymorphism), and UGT2B17 (null polymorphism). The null polymorphism in NQO1 has the potential to impair host defense. These highlighted polymorphisms are of sufficient frequency to be prioritized for consideration in chemical risk assessments. In contrast, SNPs in EPHX1 are not sufficiently influential or defined for inclusion in risk models. The current analysis is an important first step in bringing the highlighted polymorphisms into a physiologically based pharmacokinetic (PBPK) modeling framework.

Smoking, the xenobiotic pathway, and clubfoot

BACKGROUND

Isolated clubfoot is a common orthopedic birth defect that affects approximately 135,000 newborns worldwide. It is characterized by ankle equinus, hindfoot varus, and forefoot adductus. Although numerous studies suggest a multifactorial etiology, the specific genetic and environmental components have yet to be delineated. Maternal smoking during pregnancy is the only common environmental factor consistently shown to increase the risk for clubfoot. Moreover, a positive family history of clubfoot, in conjunction with maternal smoking, increases the risk 20-fold. These findings suggest that genetic variation in smoking metabolism (xenobiotic) genes may increase susceptibility to clubfoot. Based on this reasoning, we interrogated eight candidate genes from the xenobiotic metabolism.

METHODS

Twenty-two single-nucleotide polymorphisms and two null alleles in these genes (CYP1A1, CYP1A2, CYP1B1, CYP2A6, EPHX1, NAT2, GSTM1, and GSTT1) were genotyped in a dataset composed of non-Hispanic white and Hispanic multiplex and simplex families.

RESULTS

Only rs1048943/CYP1A1 had significantly altered transmission in the aggregate and multiplex non-Hispanic white datasets (p = 0.003 and p = 0.009, respectively). Perturbation of CYP1A1 can cause an increase in harmful, adduct-forming metabolic intermediates. A significant interaction between EPHX1 and NAT2 was also found (p = 0.007). Importantly, for CYP1A2, significant maternal (p = 0.03; relative risk [RR] = 1.24; 95% confidence interval [CI], 1.04-1.44) and fetal (p = 0.01; RR = 1.33; 95% CI, 1.13-1.54) genotypic effects were identified, suggesting that both maternal and fetal genotypes can negatively impact limb development. No association was found between maternal smoking status and variation in xenobiotic metabolism genes.

CONCLUSION

Together, these results suggest that xenobiotic metabolism genes are unlikely to play a major role in clubfoot; however, perturbation of this pathway may still play a contributory role.

Interactions between cigarette smoking and selected polymorphisms in xenobiotic metabolizing enzymes in risk for colorectal cancer: A case-only analysis

The metabolism of xenobiotics is complex and involves multiple steps and multiple enzymes. Genetic variation in the genes encoding these enzymes as well as the level of exposure to the substrates of these enzymes could alter metabolism and clearance of potential carcinogens and thus alter cancer susceptibility. This study examined interaction effect between smoking and two single nucleotide polymorphisms (SNPs)-CYP1A1 c.1384A>G (p.Ile462Val) and EPHX1 c.337T>C (p.Tyr113His)-in modulating colorectal cancer (CRC) risk. The SNPs were selected a priori based on functional significance. In a case-only analysis, unconditional logistic regression was used to examine the associations between smoking and each SNP and between the two SNPs in 786 patients with nonfamilial CRC. There was significant multiplicative interaction for CRC risk between smoking and EPHX1 c.337T>C (odds ratio [OR] = 1.37, 95% confidence interval [CI] = 1.03-1.81, P = 0.03), particularly among smokers with a history of greater than 20 pack-years of smoking (OR = 1.52, 95% CI = 1.07-2.16, P = 0.02). In addition, there was gene-gene interaction between EPHX1 c.337T>C and CYP1A1 c.1384A>G (OR = 1.61, 95% CI = 1.02-2.55, P = 0.04). Smokers with any variant allele of EPHX1 were at increased risk for CRC, as were individuals with any variant allele of CYP1A1 together with any variant allele of EPHX1. Thus, the study of gene-environment and gene-gene interactions may help to identify high-risk subgroups that can be targeted for intensive smoking cessation and CRC screening interventions.

Analyses of association between PPAR gamma and EPHX1 polymorphisms and susceptibility to COPD in a Hungarian cohort, a case-control study

Background

In addition to smoking, genetic predisposition is believed to play a major role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Genetic association studies of new candidate genes in COPD may lead to improved understanding of the pathogenesis of the disease.

Methods

Two proposed casual single nucleotide polymorphisms (SNP) (rs1051740, rs2234922) in microsomal epoxide hydrolase (EPHX1) and three SNPs (rs1801282, rs1800571, rs3856806) in peroxisome proliferator-activated receptor gamma (PPARG), a new candidate gene, were genotyped in a case-control study (272 COPD patients and 301 controls subjects) in Hungary. Allele frequencies and genotype distributions were compared between the two cohorts and trend test was also used to evaluate association between SNPs and COPD. To estimate the strength of association, odds ratios (OR) (with 95% CI) were calculated and potential confounding variables were tested in logistic regression analysis. Association between haplotypes and COPD outcome was also assessed.

Results

The distribution of imputed EPHX1 phenotypes was significantly different between the COPD and the control group (P = 0.041), OR for the slow activity phenotype was 1.639 (95% CI = 1.08- 2.49; P = 0.021) in our study. In logistic regression analysis adjusted for both variants, also age and pack-year, the rare allele of His447His of PPARG showed significant association with COPD outcome (OR = 1.853, 95% CI = 1.09-3.14, P = 0.0218). In haplotype analysis the GC haplotype of PPARG (OR = 0.512, 95% CI = 0.27-0.96, P = 0.035) conferred reduced risk for COPD.

Conclusions

The "slow" activity-associated genotypes of EPHX1 were associated with increased risk of COPD. The minor His447His allele of PPARG significantly increased; and the haplotype containing the minor Pro12Ala and the major His447His polymorphisms of PPARG decreased the risk of COPD.

Microsomal epoxide hydrolase gene polymorphisms and susceptibility to chronic obstructive pulmonary disease in the Tunisian population

It is well known that cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD). However, only 10%-20% of chronic heavy cigarette smokers develop symptomatic disease, which suggests the presence of genetic susceptibility. Microsomal epoxide hydrolase (EPHX1) is an enzyme involved in the protective mechanism against oxidative stress. It has been reported that gene polymorphisms of this enzyme may be associated with variations in EPHX1 activity. In this study, we aimed at investigating the relationship between EPHX1 polymorphisms and susceptibility to COPD in the Tunisian population. EPHX1 exon 3 (rs1051740, Tyr113His) and exon 4 (rs2234922, His139Arg) polymorphisms were genotyped by polymerase chain reaction followed by restriction fragment length polymorphism analysis. These techniques were used to examine a total of 416 Tunisian individuals, including 182 blood donors and a group of 234 COPD patients. All subjects were not related. An increased risk for COPD was observed in subjects with EPHX1 His113-His113 genotype (odds ratio = 2.168; confidence interval 1.098-4.283; p = 0.02386). However, multivariate logistic regression analysis showed no significant relationship between the mutant genotype and the disease after adjustment for sex, age, body mass index, smoking status, and pack-year smoking (odds ratio = 1.524; confidence interval, 0.991-6.058; p = 0.06137). Regarding the two subtypes of COPD, our investigations demonstrated that there is no significant correlation between exon 3 polymorphism and the chronic bronchitis subgroup (p = 0.09034). The relation between exon 3 polymorphism and emphysema was significant in the univariate analysis (p = 0.02257), but no association was found after controlling for classic risk factors (p = 0.06273). In conclusion, our results showed that there is a weak relation between 113His genotype and COPD, and no apparent relation between 139Arg and COPD in the studied Tunisian population.

VKORC1-1639G>A, CYP2C9, EPHX1691A>G genotype, body weight, and age are important predictors for warfarin maintenance doses in patients with mechanical heart valve prostheses in southwest China

OBJECTIVE

To investigate the contribution of genetic polymorphisms of vitamin K epoxide reductase complex subunit 1 gene VKORC1-1639G>A, cytochrome P450 2C9 gene (CYP2C9), EPHXI, and clinical factors to warfarin sensitivity in southwest Chinese Han patients with mechanical heart valve prostheses.

METHODS

A total of 127 patients with mechanical heart valve prostheses who have been followed up at our department during the past 23 years were enrolled in this study and compared to a control group that consisted of 133 randomly selected healthy blood donors. These Chinese patients met stable warfarin dosage requirements and had reached the target international normalized ratio (INR) of 1.5-2.0. PCR and direct sequencing were carried out to identify the polymorphisms of VKORC1-1639G>A (rs9923231), CYP2C9*3 (rs1057910), CYP2C9 IVS3-65G>C (rs9332127), and EPHX1691A>G (rs4653436). In addition, total and free (non-protein-bound) warfarin concentrations were analyzed.

RESULTS AND CONCLUSIONS

There were great interindividual differences in warfarin maintenance dosage (ranging from 0.6 to 8.4 mg/day) among the 127 patients with mechanical heart valve prostheses. VKORC1-1639G>A, CYP2C9, EPHX1691A>G polymorphism, body weight, and age were found to affect the dose demands. Multiple linear regression models incorporating genetic polymorphisms of VKORC1, CYP2C9, EPHX1691A>G, and the nongenetic factors of age and body weight were developed, and explained up to 76.8% of the total variation (adjusted R (2) of 0.743) in warfarin maintenance doses in southwest Chinese patients with mechanical heart valve prostheses.

Update on the Genetic Polymorphisms of Drug-Metabolizing Enzymes in Antiepileptic Drug Therapy

Genetic polymorphisms in the genes that encode drug-metabolizing enzymes are implicated in the inter-individual variability in the pharmacokinetics and pharmaco-dynamics of antiepileptic drugs (AEDs). However, the clinical impact of these polymorphisms on AED therapy still remains controversial. The defective alleles of cytochrome P450 (CYP) 2C9 and/or CYP2C19 could affect not only the pharmacokinetics, but also the pharmacodynamics of phenytoin therapy. CYP2C19 deficient genotypes were associated with the higher serum concentration of an active metabolite of clobazam, N-desmethylclobazam, and with the higher clinical efficacy of clobazam therapy than the other CYP2C19 genotypes. The defective alleles of CYP2C9 and/or CYP2C19 were also found to have clinically significant effects on the inter-individual variabilities in the population pharmacokinetics of phenobarbital, valproic acid and zonisamide. EPHX1 polymorphisms may be associated with the pharmacokinetics of carbamazepine and the risk of phenytoin-induced congenital malformations. Similarly, the UDP-glucuronosyltransferase 2B7 genotype may affect the pharmacokinetics of lamotrigine. Gluthatione S-transferase null genotypes are implicated in an increased risk of hepatotoxicity caused by carbamazepine and valproic acid. This article summarizes the state of research on the effects of mutations of drug-metabolizing enzymes on the pharmacokinetics and pharmacodynamics of AED therapies. Future directions for the dose-adjustment of AED are discussed.

Modulation of carcinogen metabolizing enzymes by chromanone A; a new chromone derivative from algicolous marine fungus Penicillium sp

A marine fungal isolate, Penicillium sp. fungus isolated from seaweed, Ulva sp., led to the isolation of a new chromone derivatives, 2-(hydroxymethyl)-8-methoxy-3-methyl-4H-chromen-4-one (chromanone A). The structure was determined by interpretation of their spectroscopic data (1D and 2D NMR, MS, UV and IR). At the nitiation stage of carcinogenesis, carcinogens is activated by cytochrome P-450 1A (CYP1A) and detoxified by glutathione S-transferases (GST), quinine reductase (QR), and epoxide hydrolase (mEH). We tested the modulatory effect of chromanone A on these carcinogen metabolizing enzymes. The results indicated that chromanone A (4μg/ml) is a promising inhibitor of CYP1A activity up to 60% of the stimulated-CYP1A in murine hepatoma cells (Hepa1c1c7), and it significantly induced GST but not total thiols at low concentrations. Chromanone A had no influence on QR activity, while it resulted in a significant dose-dependant enhancement mEH activity in Hepa1c1c7 cells (P<0.05-0.01). Additionally, chromanone A possessed a potent specific radical scavenging activity against hydroxyl radicals more than peroxyl radicals that may be responsible for the inhibitory effect of chromanone A on the induced-DNA damage in cells. In conclusion, this study proved that chromanone A may act as an active tumor anti-initiating via modulation of carcinogen metabolizing enzymes and protection from DNA damage.

Genetic polymorphisms of EPHX1, Gsk3beta, TNFSF8 and myeloma cell DKK-1 expression linked to bone disease in myeloma

Bone disease in myeloma occurs as a result of complex interactions between myeloma cells and the bone marrow microenvironment. A custom-built DNA single nucleotide polymorphism (SNP) chip containing 3404 SNPs was used to test genomic DNA from myeloma patients classified by the extent of bone disease. Correlations identified with a Total Therapy 2 (TT2) (Arkansas) data set were validated with Eastern Cooperative Oncology Group (ECOG) and Southwest Oncology Group (SWOG) data sets. Univariate correlates with bone disease included: EPHX1, IGF1R, IL-4 and Gsk3beta. SNP signatures were linked to the number of bone lesions, log(2) DKK-1 myeloma cell expression levels and patient survival. Using stepwise multivariate regression analysis, the following SNPs: EPHX1 (P=0.0026); log(2) DKK-1 expression (P=0.0046); serum lactic dehydrogenase (LDH) (P=0.0074); Gsk3beta (P=0.02) and TNFSF8 (P=0.04) were linked to bone disease. This assessment of genetic polymorphisms identifies SNPs with both potential biological relevance and utility in prognostic models of myeloma bone disease.

Mammalian epoxide hydrolases in xenobiotic metabolism and signalling

Epoxide hydrolases catalyse the hydrolysis of electrophilic--and therefore potentially genotoxic--epoxides to the corresponding less reactive vicinal diols, which explains the classification of epoxide hydrolases as typical detoxifying enzymes. The best example is mammalian microsomal epoxide hydrolase (mEH)-an enzyme prone to detoxification-due to a high expression level in the liver, a broad substrate selectivity, as well as inducibility by foreign compounds. The mEH is capable of inactivating a large number of structurally different, highly reactive epoxides and hence is an important part of the enzymatic defence of our organism against adverse effects of foreign compounds. Furthermore, evidence is accumulating that mammalian epoxide hydrolases play physiological roles other than detoxification, particularly through involvement in signalling processes. This certainly holds true for soluble epoxide hydrolase (sEH) whose main function seems to be the turnover of lipid derived epoxides, which are signalling lipids with diverse functions in regulatory processes, such as control of blood pressure, inflammatory processes, cell proliferation and nociception. In recent years, the sEH has attracted attention as a promising target for pharmacological inhibition to treat hypertension and possibly other diseases. Recently, new hitherto uncharacterised epoxide hydrolases could be identified in mammals by genome analysis. The expression pattern and substrate selectivity of these new epoxide hydrolases suggests their participation in signalling processes rather than a role in detoxification. Taken together, epoxide hydrolases (1) play a central role in the detoxification of genotoxic epoxides and (2) have an important function in the regulation of physiological processes by the control of signalling molecules with an epoxide structure.

ATSDR evaluation of health effects of benzene and relevance to public health

As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites that have the greatest public health impact. These profiles comprehensively summarize toxicological and environmental information. This article constitutes the release of portions of the Toxicological Profile for Benzene. The primary purpose of this article is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective on the toxicology of benzene. It contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health.

Biomarkers of human exposure to acrylamide and relation to polymorphisms in metabolizing genes

Acrylamide (AA) is formed in heat treated carbohydrate rich foods in the so-called Maillard reaction. AA is readily absorbed in the body and converted to glycidamide (GA) by epoxidation by the CYP2E1 (cytochrome P450 2E) enzyme. Both AA and GA may be detoxified through direct conjunction to glutathione by glutathione-S-transferases and GA by hydrolysis to glyceramide. Recently, we reported that biomarkers of AA exposure reflect intake of major food sources of AA; there were large interindividual variations in the blood ratio of GA-Hb/AA-Hb (GA- and AA-hemoglobin adducts). In this study we investigated whether the ratio of GA-Hb/AA-Hb in subjects could be related to polymorphic differences in genes coding for metabolizing enzymes CYP2E1, EPHX1 (microsomal epoxide hydrolase), GSTM1, GSTT1, and GSTP1, all being expected to be involved in the activation and detoxification of AA-associated adducts. We found significant associations between GSTM1 and GSTT1 genotypes and the ratio of GA-Hb/AA-Hb (p = 0.039 and p = 0.006, respectively). The ratio of GA-Hb/AA-Hb in individuals with the combined GSTM1- and GSTT1-null variants was significantly (p = 0.029) higher than those with the wild-type genotypes. Although the number of subjects was small, there were also significant associations with other combinations; CYP2E1 (Val179Val) plus GSTM1-null (p = 0.022); CYP2E1 (Val/Val), GSTM1-null plus GSTT1-null (p = 0.047); and CYP2E1 (Val/Val), GSTT1 null, EPHX1 (Tyr113Tyr) plus EPHX1 (His139Arg) (p = 0.018). Individuals with these combined genotypes had significantly higher blood ratio of GA-Hb/AA-Hb than other combinations. The observed associations correspond with what would be expected from the relative roles of these enzymes in activation and detoxification of AA, except for individuals with the EPHX1 (His139Arg) variant. The internal dose of genotoxic metabolite and also the concentration of AA in blood seem to be affected by these polymorphic genes. The genotypes and their combination may constitute useful biomarkers for the assessment of individual susceptibility to AA intake, and could add to the precision of epidemiological studies of dietary cancer.

Effect of CYP2E1 gene deletion in mice on expression of microsomal epoxide hydrolase in response to VCD exposure

Females are born with a finite number of primordial follicles. 4-Vinylcyclohexene diepoxide (VCD) is a metabolite formed by epoxidation of 4-vinylcyclohexene (VCH) via its two monoepoxides 1,2- and 7,8-4-vinylcyclohexene monoepoxide (VCM). VCD specifically destroys small preantral (primordial and small primary) follicles in the rodent ovary. The phase I enzyme, cytochrome P450 isoform 2E1 (CYP2E1) is involved in ovarian metabolism of VCM to VCD. Further, microsomal epoxide hydrolase (mEH) can detoxify VCD to an inactive tetrol (4-(1,2-dihydroxy)ethyl-1,2-dihydroxycyclohexane). This study evaluated the effects of VCD-induced ovotoxicity on mEH in CYP2E1+/+ and -/- mice (129S(1)/SvImJ background strain) using a postnatal day 4 mouse whole ovary culture system. The hypothesis of our study is that there is a relationship between CYP2E1 and mEH gene expression in the mouse ovary. Relative to control, VCD exposure caused follicle loss (p < 0.05) in ovaries from both genotypes; however, after 15 days, this loss was greater (p < 0.05) in CYP2E1+/+ ovaries. In a time course (2-15 days), relative to control, VCD (5 microM) caused an increase (p < 0.05) in mEH mRNA by 0.5-fold (day 10) and 1.84-fold (day 15) in CYP2E1-/- but not +/+ ovaries. 7,12-Dimethylbenz[a]anthracene (DMBA) also destroys ovarian follicles but, unlike VCD, is bioactivated by mEH to an ovotoxic 3,4-diol-1,2-epoxide metabolite. Incubation of ovaries in increasing concentrations of DMBA (0.5-1 microM, 15 days) resulted in greater (p < 0.05) follicle loss in CYP2E1-/-, relative to +/+ ovaries. With greater mEH (CYP2E1-/-), increased follicle loss with DMBA (bioactivation) and decreased follicle loss with VCD (detoxification) support that ovarian expression of CYP2E1 and mEH may be linked.

In vitro metabolism of the epoxide substructure of cryptophycins by cytosolic glutathione S-transferase: species differences and stereoselectivity

The enzyme kinetics of the glutathione (GSH) conjugation of cryptophycin 52 (C52, R-stereoisomer) and cryptophycin 53 (C53, S-stereoisomer) by cytosolic glutathione S-transferases (cGSTs) from human, rat, mouse, dog and monkey liver were studied. Vmax, Km, and CLint values for glutathione conjugation of C52 (R-stereoisomer) were 0.10 +/- 0.01 nmol min-1 mg-1, 3.24 +/- 0.23 microM, and (3.15 +/- 0.09) x 10(-2) ml min-1 mg-1, respectively, in human cytosol. Due to limited solubility relative to the Km, only CLint values were determined in rat ((7.76 +/- 0.10) x 10-2 ml min-1 mg-1) and mouse ((7.61 +/- 0.50) x 10(-2) ml min-1 mg-1) cytosol. Enzyme kinetic parameters could not be determined for C53 (S-stereoisomer). Microsomal GSH conjugation in human, rat, and mouse was attributed to cytosolic contamination. No GSH conjugation was seen in any biological matrix from dog or monkey. There was little GSH conjugation of C53 by cytosol or microsomes from any species. The metabolism of C52 and C53 by epoxide hydrolase was also investigated. No diol product was observed in any biological matrix from any species. Thus, cGSTs are primarily responsible for C52 metabolism.

Polymorphisms in metabolic genes related to tobacco smoke and the risk of gastric cancer in the European prospective investigation into cancer and nutrition

Metabolizing enzymes, which often display genetic polymorphisms, are involved in the activation of compounds present in tobacco smoke that may be relevant to gastric carcinogenesis. We report the results of a study looking at the association between risk of gastric adenocarcinoma and polymorphisms in genes CYP1A1, CYP1A2, EPHX1, and GSTT1. A nested case-control study was carried out within the European Prospective Investigation into Cancer and Nutrition, developed in 10 European countries. The study includes 243 newly diagnosed cases of histologically confirmed gastric adenocarcinoma and 946 controls matched by center, age, sex, and date of blood collection. Genotypes were determined in nuclear DNA from WBCs. We found an increased risk of gastric cancer for homozygotes for C (histidine) variant in Y113H of EPHX1 (odds ratio, 1.91; 95% confidence interval, 1.19-3.07) compared with subjects with TC/TT. There was also a significant increased risk for smokers carrying at least one variant allele A in Ex7+129C>A (m4) of CYP1A1 and never smokers with null GSTT1 and allele A in the locus -3859G>A of CYP1A2. Most of these genes are involved in the activation and detoxification of polycyclic aromatic hydrocarbons, suggesting a potential role of these compounds in gastric carcinogenesis.

EPHX1 gene polymorphisms and individual susceptibility to lung cancer

We investigated the roles of EPHX1 Tyr113His and His139Arg polymorphisms in lung cancer susceptibility in a Finnish study population comprising of 230 lung cancer cases and a large control group (n=2105). The controls were distributed into five age strata, which enabled us to examine the potential age-related changes in the putative EPHX1 at-risk genotypes in the cancer free population. Although the exon 3 slow activity associated allele (His113) containing genotypes posed a decreased lung cancer risk compared with the homozygous wild-type Tyr113/Tyr113 genotype (OR, 0.68; 95% CI, 0.49-0.94), no association was seen for the EPHX1 phenotypes interpreted from the combined exons 3 and 4 genotype data. Neither was any difference seen in the prevalence of the EPHX1 Tyr113His genotypes or interpreted EPHX1 phenotypes in the different age groups.

Expression of microsomal epoxide hydrolase is elevated in Alzheimer's hippocampus and induced by exogenous β-amyloid and trimethyl-tin

The brain is a potential target for drugs and environmental toxins. Microsomal epoxide hydrolase (mEH) is one of several critical biotransformation enzymes in xenobiotic metabolism and detoxification. In the present study, we report that the expression of mEH is significantly elevated in the hippocampus and associated cortex, but not in the cerebellum, in Alzheimer's disease (AD) patients. A large proportion of the mEH-positive cells are located around beta-amyloid plaques. The mEH-positive-staining cells are astrocytes and pyramidal neurons. Western blotting analysis confirmed increased expression of mEH in AD hippocampal tissues. In primary hippocampal glial culture, beta-amyloid aggregation stimulated mEH expression in the astrocytes, which displayed a patchy distribution. An environmental neurotoxic agent, trimethyl-tin, also activated mEH expression in rat hippocampus and entorhinal cortex. The present study demonstrates a significant increase in mEH expression in the AD hippocampus, a region showing abundant neuropathology in AD. The expression of mEH could also be elevated by exposure to exogenous beta-amyloid in vitro and environmental toxins in vivo. Our studies suggest that mEH may play a role in pathogenesis of neurodegeneration in response to environmental stress.

Variation in genes relevant to aromatic hydrocarbon metabolism and the risk of adult brain tumors

Genes involved in phase I and phase II regulation of aromatic hydrocarbon-induced effects exhibit sequence variability that may mediate the risk of adult brain tumors. We evaluated associations between gene variants in CYP1A1, CYP1B1, GSTM3, EPHX1, and NQO1 and adult brain tumor incidence. Cases were patients with glioma (n = 489), meningioma (n = 197), or acoustic neuroma (n = 96) diagnosed from 1994 to 1998 at three U.S. hospitals. Controls were 799 patients admitted to the same hospitals for nonmalignant conditions. DNA was extracted from blood samples collected from 1277 subjects, and genotyping was conducted for CYP1A1 I462V, CYP1B1 V432L, EPHX1 Y113H, GSTM3 *A/*B (intron 6 deletion), and NQO1 P187S. The CYP1B1 V432L homozygous variant was associated with decreased risk of meningioma (odds ratio [OR] = 0.6; 95% CI, 0.3-1.0) but not the other tumor types. The GSTM3 *B/*B genotype was associated with increased risk of glioma (OR = 2.3; 95% CI, 1.0-5.2) and meningioma (OR = 3.6; 95% CI, 1.3-9.8). Increased risks associated with GSTM3 *B/*B were observed in younger subjects (age < 50) and older subjects (age > or = 50), in men and women, and within each study site. The magnitude of association for GSTM3 with glioma and meningioma was greater among ever-smokers than among those who had never smoked. None of the other genotypes showed consistent associations with any tumor type. The association with the GSTM3 *B allele, while intriguing, requires replication, and additional research is needed to clarify the function of the GSTM3 alleles studied here.

Role of epoxide hydrolase, NAD(P)H:quinone oxidoreductase, cytochrome P450 2E1 or alcohol dehydrogenase genotypes in susceptibility to colorectal cancer

Colorectal cancer (CRC) is one of the most common forms of cancer in Western countries. CRC has been associated with genetic and lifestyle factors. Individual susceptibility to CRC may be due partly to variations in detoxification capacity in the gastrointestinal tract. Genetic polymorphisms in detoxification enzymes may result in variations in detoxification activities, which subsequently might influence the levels of toxic/carcinogenic compounds, and this may influence the risk for CRC. Therefore, we determined whether polymorphisms in the genes coding for microsomal epoxide hydrolase (EPHX1), NAD(P)H:quinone oxidoreductase (NQO1), cytochrome P450 2E1 (CYP2E1) and alcohol dehydrogenase (ADH3) predispose to the development of CRC. DNA samples were obtained from 371 patients with sporadic CRC and 415 healthy controls. Patients and controls were all of Caucasian origin. All genetic polymorphisms were determined by polymerase chain reaction, eventually followed by restriction-fragment-length-polymorphism analyses, except for the EPHX1 codon 113 polymorphism, which was genotyped by an allele-specific discrimination assay. Calculation of crude Odds Ratios (ORs) revealed an increased risk for CRC associated with variant NQO1 (OR 1.5, 95% CI 1.1-2.0) and CYP2E1 intron 6 genotypes (OR 2.2, 95% CI 1.3-3.8). However, after adjustment for age and gender, logistic regression analyses only showed a statistically significant risk for CRC associated with variant NQO1 genotypes (OR 1.6, 95% CI 1.03-2.4). No associations were found between CRC and the other polymorphic genes as mentioned above. In conclusion, these data suggest that the presence of variant NQO1 genotypes, with expected reduced enzyme activities might enhance susceptibility to CRC.

Occupational exposure to polycyclic aromatic hydrocarbons in German industries: association between exogenous exposure and urinary metabolites and its modulation by enzyme polymorphisms

A cross-sectional study was conducted in 170 German workers exposed to polycyclic aromatic hydrocarbons (PAH) to investigate the role of 11 polymorphisms of CYP1A1, CYP1A2, CYP1B1, CYP3A4, EPHX1, GSTM1, GSTT1, and GSTP1 in the association between occupational exposure to PAH and urinary PAH metabolites. Polymorphisms were genotyped with real-time PCR. Exposure to 16 PAH was measured by personal air sampling. Urinary concentrations of 1-hydroxypyrene (1-OHP) and the sum of 1-, 2+9-, 3-, and 4-hydroxyphenanthrenes (OHPhe) were determined post-shift. Urinary 1-OHP and OHPhe correlated significantly with exogenous pyrene (Spearman r=0.52, p<0.0001) and phenanthrene (Spearman r=0.72, p<0.0001), respectively. ANCOVA was applied to investigate potential predictors of the metabolite levels. Current smoking and type of industry turned out to be predictors of 1-OHP but not of OHPhe. CYP1A1 3801TC carriers showed 1.6-fold higher OHPhe levels than 3801TT carriers (p=0.03). EPHX1 113HH was associated with higher and 139RR with lower metabolite levels when compared with the corresponding reference genotypes (113YY; 139HH). In comparison to GSTP1 114AA, carriers of the V allele had 1.5-fold higher 1-OHP (p=0.03) and 2-fold higher OHPhe concentrations (p=0.001). OHPhe turned out to be also a suitable biomarker of occupational PAH exposure. The association with ambient PAH exposure and the influence of polymorphisms was more pronounced for OHPhe.

Epoxide hydrolases: their roles and interactions with lipid metabolism

The epoxide hydrolases (EHs) are enzymes present in all living organisms, which transform epoxide containing lipids by the addition of water. In plants and animals, many of these lipid substrates have potent biologically activities, such as host defenses, control of development, regulation of inflammation and blood pressure. Thus the EHs have important and diverse biological roles with profound effects on the physiological state of the host organisms. Currently, seven distinct epoxide hydrolase sub-types are recognized in higher organisms. These include the plant soluble EHs, the mammalian soluble epoxide hydrolase, the hepoxilin hydrolase, leukotriene A4 hydrolase, the microsomal epoxide hydrolase, and the insect juvenile hormone epoxide hydrolase. While our understanding of these enzymes has progressed at different rates, here we discuss the current state of knowledge for each of these enzymes, along with a distillation of our current understanding of their endogenous roles. By reviewing the entire enzyme class together, both commonalities and discrepancies in our understanding are highlighted and important directions for future research pertaining to these enzymes are indicated.

Microsomal Epoxide Hydrolase, Endotoxin, and Lung Function Decline in Cotton Textile Workers

Occupational exposure to endotoxin in organic dust may induce lung function decline. Microsomal epoxide hydrolase (mEH) detoxifies reactive oxygen species generated by endotoxin exposure, and polymorphisms of the mEH gene are associated with altered enzyme activity. We investigated the associations between mEH polymorphisms, endotoxin exposure, and lung function decline in a 20-year prospective study of 265 workers exposed to endotoxin and 234 control subjects. mEH Tyr113His and His139Arg polymorphisms were genotyped by the 5' nuclease assay, and data were analyzed using multivariate linear regression models, adjusting for important covariates. Overall, the annual decline rate of FEV1 was 29.47 ml during the 20-year follow-up. Endotoxin exposure was associated with faster lung function decline among genotypes associated with slower enzyme activity: estimates (SE) of annual FEV1 decline rates for endotoxin exposure were -2.33 (2.07), -2.81 (1.66), and -6.73 (2.83) ml for Tyr/Tyr, Tyr/His, and His/His genotype groups, respectively, for the Tyr113His polymorphism; and -1.82 (2.58) and -4.27 (1.33) ml for Arg/Arg + His/Arg and His/His genotypes, respectively, for the His139Arg polymorphism. We conclude that mEH polymorphisms modify the association between occupational endotoxin exposure and longitudinal lung function decline.

Microsomal Epoxide Hydrolase Polymorphisms and Risk for Advanced Colorectal Adenoma

Cigarette smoking is a risk factor for colorectal adenoma, a precursor of colorectal cancer. Microsomal epoxide hydrolase (EPHX1) metabolizes polycyclic aromatic hydrocarbons, carcinogens found in cigarette smoke. Nonsynonymous variants of EPHX1 at Tyr113His (exon 3) and His139Arg (exon 4) are associated, respectively, with low (113His) and high (139Arg) predicted activity. Among participants randomized to the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we evaluated risks for advanced adenoma in relation to cigarette use and these two EPHX1 variants. We compared 772 cases with advanced adenoma (adenoma ≥1 cm or containing high-grade dysplasia or villous, including tubulovillous, elements) of the distal colon (left-sided, descending colon and sigmoid or rectum) to 777 gender- and age-matched controls who were screen-negative for left-sided adenoma. Compared to those with homozygous genotypes predicting low EPHX1 activity, advanced adenoma risks tended to be elevated for carriers of 113TyrTyr [odds ratios (OR), 1.5; 95% confidence intervals (CI), 1.0-2.2] and 139ArgArg (OR, 1.4; 95% CI, 0.8-2.5) and for subjects who carried a greater number of the alleles (113Tyr or 139Arg) associated with high predicted enzymatic activity (Ptrend = 0.03). The increased risk associated with the increasing number of putative high-activity alleles was most apparent among current and recent (quit &lt;10 years) cigarette smokers (Ptrend = 0.02). In conclusion, EPHX1 variants at codon 113 and 139 associated with high predicted enzymatic activity appear to increase risk for colorectal adenoma, particularly among recent and current smokers.

Epoxide hydrolase and CYP2C9 polymorphisms, cigarette smoking, and risk of colorectal carcinoma in the Nurses' Health Study and the Physicians' Health Study

Microsomal epoxide hydrolase (mEH) and cytochrome P450 2C9 (CYP2C9) are involved in the bioactivation and detoxification of polycyclic aromatic hydrocarbons (PAHs) derived from tobacco smoke. Two coding-region mEH variants (Tyr113His, His139Arg) and CYP2C9 variants (Arg144Cys, Ile359Leu) have been described and affect enzyme specific activity. We investigated these polymorphisms and tested interactions with smoking in relationship to risk of colorectal carcinoma in two case-control studies nested in the Nurses' Health Study (NHS) and Physicians' Health Study (PHS) cohorts. mEH Tyr113His and His139Arg polymorphisms were not associated with the risk of cancer among 197 incident cases and 490 controls from the NHS. Among 273 incident cases and 453 controls from the PHS, carrying one or two copies of the 'rapid' 139Arg allele was associated with a significantly reduced risk of colorectal cancer (OR=0.70, 95% CI 0.49--0.99) when compared with His139 wild-type individuals. Risk of colorectal cancer was significantly reduced among men carrying the CYP2C9 *1/*2 genotype (OR=0.62, 95% CI 0.42--0.92) or at least one CYP2C9 variant allele (OR=0.72, 95% CI 0.52--1.00) when compared with *1/*1 wild-type individuals. For women, carrying at least one variant CYP2C9 allele was inversely associated with the risk of colorectal cancer (OR=0.85, 95% CI, 0.57--1.27) when compared with *1/*1 wild-type individuals. No statistically significant genotype-smoking or gene-gene interactions were found in this study. Our results indicate that individuals exposed to tobacco carcinogens were at increased risk of colorectal cancer and that overall risk is related to mEH and CYP2C9 genotype, although the results were not consistent between men and women.

Gene expression profiling in spleens of deoxynivalenol-exposed mice: immediate early genes as primary targets

Exposure to the trichothecene mycotoxin deoxynivalenol (DON) alters immune functions in vitro and in vivo. To gain further insight into DON's immunotoxic effects, microarrays were used to determine how acute exposure to this mycotoxin modulates gene expression profiles in murine spleen. B6C3F1 mice were treated orally with 25mg/kg body weight DON, and 2h later spleens were collected for macroarray analysis. Following normalization using a local linear regression model, expression of 116 out of 1176 genes was significantly altered compared to average expression levels in all treatment groups. When genes were arranged into an ontology tree to facilitate comparison of expression profiles between treatment groups, DON was found primarily to modulate genes associated with immunity, inflammation, and chemotaxis. Real-time polymerase chain reaction was used to confirm modulation for selected genes. DON was found to induce the cytokines interleukin (IL)-1alpha, IL-1beta, IL-6 and IL-11. In analogous fashion, DON upregulated expression of the chemokines macrophage inhibitory protein-2 (MIP-2), cytokine-induced chemoattractant protein-1 (CINC-1), monocyte chemoattractant protein (MCP)-1, MCP-3, and cytokine-responsive gene-2 (CRG-2). c-Fos, Fra-, c-Jun, and JunB, components of the activator protein-1 (AP-1) transcription factor complex, were induced by DON as well as another transcription factor, NR4A1. Four hydrolases were found to be upregulated by DON, including mitogen-activated protein kinase phosphatase 1 (MKP1), catalytic subunit beta isoform (CnAbeta), protein tyrosine phosphatase receptor type J (Ptprj), and protein tyrosine phosphatase nonreceptor type 8 (Ptpn8), whereas three other hydrolases, microsomal epoxide hydrolase (Eph) 1, histidine triad nucleotide binding protein (Hint), and proteosome subunit beta type 8 (Psmb8) were significantly decreased by the toxin. Finally, cysteine-rich protein 61 (CRP61) and heat-shock protein 40 (Hsp40), genes associated with signaling, were increased, while Jun kinase 2 (JNK2) was decreased. Taken together, data suggest that DON upregulated the expression of multiple immediate early genes, many of which are likely to contribute to the complex immunological effects reported for this and other trichothecenes.