Slow Allele Research Articles

Differences in β-naphthylamine metabolism and toxicity in Chinese hamster ovary cell lines transfected with human CYP1A2 and NAT2*4, NAT2*5B or NAT2*7B N-acetyltransferase 2 haplotypes.

β-naphthylamine (BNA) is an important aromatic amine carcinogen. Current exposures derive primarily from cigarette smoking including e-cigarettes. Occupational and environmental exposure to BNA is associated with urinary bladder cancer which is the fourth most frequent cancer in the United States. N-acetyltransferase 2 (NAT2) is an important metabolizing enzyme for aromatic amines. Previous studies investigated mutagenicity and genotoxicity of BNA in bacteria and in rabbit or rat hepatocytes. However, the effects of human NAT2 genetic polymorphism on N-acetylation and genotoxicity induced by BNA still need to be clarified. We used nucleotide excision repair-deficient Chinese hamster ovary (CHO) cells that were stably transfected with human CYP1A2 and NAT2 alleles: NAT2*4 (reference allele), NAT2*5B (variant slow acetylator allele common in Europe) or NAT2*7B (variant slow acetylator allele common in Asia). BNA N-acetylation was measured both in vitro and in situ via high-performance liquid chromatography (HPLC). Hypoxanthine phosphoribosyl transferase (HPRT) mutations, double-strand DNA breaks, and reactive oxygen species (ROS) were measured as indices of toxicity. NAT2*4 cells showed significantly higher BNA N-acetylation rates followed by NAT2*7B and NAT2*5B. BNA caused concentration-dependent increases in DNA damage and ROS levels. NAT2*7B showed significantly higher levels of HPRT mutants, DNA damage and ROS than NAT2*5B (p < 0.001, p < 0.0001, p < 0.0001 respectively) although both are slow alleles. Our findings suggest that BNA N-acetylation and toxicity are modified by NAT2 polymorphism. Furthermore, they confirm heterogeneity among slow acetylator alleles for BNA metabolism and toxicity supporting differential risk for individuals carrying NAT2*7B allele.

Influence of N‐acetyltransferase polymorphism in the N‐acetylation of asparagine and putrescine

Amino acids play central roles in cancer progression beyond their function as building blocks for protein synthesis. Because of this, targeting amino acid acquisition and uptake has been proved to be a potential therapeutic strategy to limit cancer cell growth while leaving the normal tissues largely intact. Polyamines like Putrescine (Put) are low molecular weight, aliphatic polycations found in the cells of all living organisms. Recent findings have described that abundance of N‐acetylated Asparagine (Asp) and Put are highly correlated with N‐acetylation capacity of N‐acetyltransferase 1 (NAT1). Here we tested the N‐acetylation of Asp and Put by recombinant human NAT1 and NAT2 as well as the effect of N‐acetylation polymorphisms in the metabolism of these substrates. Using genetically engineered CHO cells expressing either NAT1*4, NAT1*14, NAT2*4 or NAT2*5B alleles, in vitro N‐acetylation activity reactions were quantified using HPLC. Our results show that Asp is metabolized by both NAT1 and NAT2; enzymatic activity was quantified at different time points up to 60 min, as well as, increasing concentrations of the cofactor AcCoA. Using 100 μM of AcCoA, the formation of N‐acetyl Asp was 1.7 ±0.32 nmoles Ac‐Asp/mg protein in the reference allele (NAT1*4); on the other hand, NAT1*14 (slow) allele produced 1.12 ±0.32 nmoles Ac‐Asp/mg protein (p&lt; 0.01); increasing AcCoA to 300 μM resulted in an increase 3.98 ±0.58 and 2.93 ±0.62 nmoles Ac‐Asp/mg protein, respectively (p&lt; 0.01), Finally, Increasing the availability of AcCoA to 1 mM, produced an N‐acetylation rate of 9.82 ±3.73 and 4.64 ±0.61 nmoles Ac‐Asp/mg protein (p&lt; 0.001). For NAT2, in the presence of 100 μM of AcCoA, the reference allele (NAT2*4) produced 1.43 ±0.6, whereas NAT2*5B (slow) produced 1.05 ±0.19 nmoles Ac‐Asp/mg protein (p&lt; 0.05). 300 μM of AcCoA increased the rate to 3.1 ±0.93 vs 2.4 ±0.52 nmoles Ac‐Asp/mg protein (p&lt; 0.05). Finally, using 1 mM AcCoA, N‐acetylation increased to 7.23 ±2.69 vs 5.11 ±0.79 nmoles Ac‐Asp/mg protein (p&lt; 0.01). Both NAT1 and NAT2 catalyzed the Put N‐acetylation. For NAT1 in the presence of 100 μM of AcCoA, we observed the formation of 0.19 ±0.03 nmoles Ac‐Put/mg protein in NAT1*4, and 0.108 ±0.02 nmoles Ac‐Put/mg protein in NAT1*14 allele (p&lt; 0.05). Using 300 μM of AcCoA, 0.27 ±0.02 in NAT1*4 vs 0.14 ±0.3 nmoles Ac‐Put/mg protein in NAT1*14 (p&lt; 0.05). Finally, 1 mM of AcCoA yielded 0.43 ±0.03 vs 0.23 ±0.03 nmoles Ac‐Put/mg protein, respectively (p&lt; 0.05). Finally, for NAT2 and Put N‐acetylation, our results show that the reference allele produces 0.26 ±0.03 vs 0.16 ±0.04 nmoles Ac‐Put/mg protein in the slow (NAT2*5B) allele when we used 100 μM of AcCoa (p&lt; 0.05), 0.3 ±0.03 and 0.22 ±0.02 nmoles Ac‐Put/mg protein respectively when we used 300 μM of AcCoA; and 0.4 ±0.03 vs 0.3 ±0.02 nmoles Ac‐Put/mg protein respectively when we used 1 mM AcCoA. In conclusion, these results show that NAT1 and NAT2 are capable of the N‐acetylation of endogenous compounds like Asparagine and Putrescine. Moreover, this metabolic reaction is dependent of the AcCoA present and influenced by the genetic polymorphisms. Future studies will help us understand the implications of the N‐acetylation of these compounds in cellular processes like cancer cell progression.

PHARMACOGENETIC BASES OF INDIVIDUAL SENSITIVITY AND PERSONALIZED ADMINISTRATION OF ANTIPLATELET THERAPY IN DIFFERENT ETHNIC GROUPS

Cardiovascular diseases (CVDs) are the leading cause of disability and mortality worldwide. Increased thrombosis is the trigger point for the development of various CVDs and their complications, and therefore, therapy with P2Y12-receptor inhibitors is always pathogenetically justified and vital. However, according to the various data, 10-25% of patients treated with clopidogrel have “resistance” to antiplatelet therapy. The causes for the formation of resistance are still not clear. There is no generally accepted, standard methodology for determining resistance to antiplatelet agents. In addition, there are no methodological approaches to identify the patients with resistance to antiplatelet drugs, and standardized schemes for correcting a low sensitivity to these drugs.The aim of this review was to summarize the available results of foreign and domestic studies devoted to the investigation of the effectiveness and safety problems of antiplatelet drugs administration from the point of view of the genetic predisposition to changes in their metabolism.Materials and methods. For the review, the following information from scientific literature represented in open and accessible sources for the period of 1996-2020, was used: pharmgkb.org, PubMed, Scopus, Web of Science Core Collection, Elibrary. Search queries – “Genetic features+antiplatelet therapy+ethnic groups”, “CYP2C19+clopidogrel+antiplatelet therapy effectiveness”; “Stent retrombosis+CYP2C19 polymorphism+ residual platelet reactivity” and “CYP2C19 polymorphism+ethnic groups+clopidogrel resistance” in both Russian and English equivalents. All these data are placed in electronic databases.Results. Currently, the problem of the resistance formation to antiplatelet drugs is studied insufficiently. The best thought-out issue is the research of the effect of the polymorphic alleles carriage of the CYP2C19 gene on the residual platelet reactivity in the patients administrated with dual antiplatelet treatment, including clopidogrel. In general, the analysis of open literature sources indicates the presence of a statistically significant association between the carrier of slow alleles of the CYP2C19 gene and the residual platelet reactivity, clinically manifested by thrombosis and adverse cardiovascular events. The occurrence frequency of polymorphic carriage of the CYP2C19 gene varies in different ethnic groups, so it cannot be extrapolated to individual subjects, peculiar in the ethnic diversity.Conclusion. To develop preventive and predictive measures aimed at overcoming resistance to antiplatelet agents, as well as working out methodological approaches to personalized prescribtion of this group drugs, a further investigation with the expansion of the search for causes and the study of the other genes participation of the cytochrome P450 system, is required.

Association of microsomal epoxide hydrolase gene (fast genotype) with lung functions impairment in wood workers.

Exposure to wood dust may lead to impairment of the lung functions. Microsomal epoxide hydrolase enzyme (EPHX1) was shown to take part in protection against oxidative stress. An alteration in enzyme activity might be associated with its gene polymorphisms. In vitro polymorphisms in exons 3 (His113Tyr) and 4 (Arg139His) lead to reduced activity (slow allele) and increased activity (fast allele). Macrophage inflammatory protein 2 (MIP-2) is produced in rat lung epithelial cells after exposure to fine particles. We aimed to investigate the associations between mEPHX1 polymorphisms (in exon 3 and 4) and lung function in furniture workers and assessment of MIP-2 effect. Our study was performed on 70 wood dust exposed male workers and 70 matched normal controls subjects. Ventilatory function tests were measured by spirometer, MIP-2 was performed by ELISA methods and EPHX gene was done by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods for each participant. Significant reduction in forced vital capacity (FVC%) and forced expiratory volume in the first second (FEV1) levels in Tyr-Tyr and Tyr-Hist genotypes of EPHX (exon 3) was observed. Reduced peak expiratory flow (PEF) levels and significant rise in MIP-2 levels were detected in Tyr-Tyr genotype. While high significant reduction in FVC% and FEV1 levels were shown in different genotypes in exon 4. Significant rise was observed in MIP-2 levels in Hist-Hist genotype of exon 4. An increase in duration of exposure showed positive correlation with fall in ventilatory functions. It was concluded that in Hist139Arg of EPHX gene, fast genotype (Arg-Arg) was associated with impaired ventilatory functions.

Abstract PD2-09: The role of CYP2D6 mediated tamoxifen metabolism in the suppression of ovarian function trial (SOFT)

Abstract Tamoxifen (T) is a pro-drug that undergoes CYP2D6-mediated metabolic activation to metabolites that more potently inhibit estrogen stimulated growth compared to the parent drug. While many studies have examined the role of CYP2D6 genotype in T-treated postmenopausal women, the role of CYP2D6 metabolism in premenopausal women (pre-MW) receiving T, with or without ovarian function suppression (OFS) or exemestane (E) and OFS is unknown. Methods: SOFT randomized 3066 (pre-MW) from 2003-2011 in 27 countries, stratified according to prior receipt or nonreceipt of chemotherapy and nodal status, to receive 5 years of T, T+OFS, or E+OFS. We designed a pharmacogenetics substudy (activated October 2010) to collect blood DNA from North American (NA) patients (pts) or to extract non-tumor DNA from available formalin fixed paraffin embedded (FFPE) tissue blocks. For pts with a blood sample, CYP2D6 was genotyped beginning with the Luminex Tag-It Mutation Detection Kit and when needed, with a copy number variation assay and/or sequencing assays. For pts with FFPE-derived DNA, CYP2D6 genotyping for *3, *4, *6, *9, *10, *17 and *41 was performed using a Taqman Allelic Discrimination Assay. CYP2D6 phenotypes were called by classifying pts on the basis of a combination of poor (PM: *3, *4, *5, *6, *7, *8), slow (SM: *10), intermediate (IM: *9, *17, *29, *41) and extensive metabolizer alleles (EM; all others). Activity scores (AS) from phenotypes assigned for each allele: 0 if PM, 0.25 if SM, 0.5 if IM and 1 if EM allele, and multiplied x2 or x3 if duplicate or triplicate. With concomitant use of potent CYP2D6 inhibitor, AS=0; use of weak inhibitor subtracted 0.5. Metabolizer status was defined by CYP2D6 genotype alone or in combination with CYP2D6 inhibitor use at randomization from the AS: extensive (AS 1.25 to 3), intermediate (AS &amp;gt;0.5 to &amp;lt;1.25), slow/poor (AS 0 to 0.5) metabolizer status. The laboratory was blinded to all clinical data. The substudy primary objective was to assess the association between disease-free survival (DFS) and CYP2D6 metabolizer status in the T arm, and secondarily in the T + OFS, and E + OFS arms. A Cox model estimated hazard ratios comparing status according to treatment assignment, with prespecified prognostic factors. Results: 1200/3047 (39%) randomized pts in the intention-to-treat (ITT) population had successful CYP2D6 genotyping and 50% received prior chemotherapy. Following randomization, 435/1023 (42%) NA pts provided a blood sample and CYP2D6 genotypes were derived in 435/435. Non-tumor tissue was macrodissected from 1277 available FFPE blocks, resulting in DNA concentrations of &amp;gt; 0.3 ng/ml in 1053, and successfully derived CYP2D6 genotypes for 765/3047 pts (25%). 182 (15%) pts had DFS events after 8 yrs median follow-up. Metabolizer status from genotype was 57% extensive, 29% intermediate, 15% slow/poor. Metabolizer status was not associated with DFS in pts assigned T alone (P=0.60; Table), nor in pts assigned T+OFS (P=0.41) or E+OFS (P=0.30). 11% of pts used CYP2D6 inhibitors concomitantly at randomization; for 8% it changed the metabolizer status. The results using this definition were consistent. Conclusion: This retrospective-prospective SOFT pharmacogenetics substudy found no relation of CYP2D6 metabolizer status with DFS in premenopausal pts receiving T, T + OFS, or E + OFS. Given that 50% were pretreated with chemotherapy, further study is needed regarding the role of CYP2D6 metabolism in patients treated with T monotherapy. TableTreatment GroupN pts (N events)Comparison (N pts)Hazard Ratio95% CITamoxifen324 (56)Intermediate (114) vs Extensive (210)0.780.43-1.39Tamoxifen265 (52)Slow/Poor (55) vs Extensive (210)1.110.58-2.13Tamoxifen + OFS357 (46)Intermediate (122) vs Extensive (235)0.730.38-1.40Tamoxifen + OFS299 (45)Slow/Poor (64) vs Extensive (235)1.250.64-2.43Exemestane + OFS344 (46)Intermediate (107) vs Extensive (237)0.590.28-1.22Exemestane + OFS293 (47)Slow/Poor (56) vs Extensive (237)1.130.56-2.27 Citation Format: Matthew P. Goetz, Gini F. Fleming, Mary Kuffel, John R. Hawse, John L. Black, Richard Weinshilboum, James N. Ingle, Patrizia dell’Orto, Olivia Biasi, Roswitha Kammler, Sherene Loi, Marco Colleoni, Giuseppe Viale, Prudence A Francis, Meredith M Regan. The role of CYP2D6 mediated tamoxifen metabolism in the suppression of ovarian function trial (SOFT) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD2-09.

Pharmacogenetics of non-steroidal anti-inflammatory drugs: existing problems for clinical practice

NSAIDs are the most commonly used drugs in clinical practice for pain relief in various diseases. To date, considerable scientific material has been accumulated on the pharmacogenetics of NSAIDs and the role of genetic factors that can influence the pharmacokinetics and pharmacodynamics of drugs, changing the efficacy and toxicity profile. The most clinically significant changes in pharmacokinetics in carriers of slow alleles of CYP2C9*3 have been identified for celecoxib and flurbiprofen, which determines the need for testing and lowering of drug doses. Studies were carried out to study the role of polymorphism of the metabolizing enzymes CYP2C9, CYP2C8, UGT in the development of gastrotoxicity and gastrointestinal bleeding during application NSAIDs, as well as diclofenac’s hepatotoxicity. The association of «slow» alleles CYP2C8*3 and CYP2C9*2,*3 with the risk of gastrointestinal bleeding associated with NSAID use, which are substrates of CYP2C9 and CYP2C8, is shown. The effect of variants of alleles PTGS1 (gene COX-1) and PTGS2 (gene COX-2) on pharmacodynamics, efficacy and toxicity of NSAIDs, in particular, the severity of the analgesic effect and cardiotoxicity of the drugs, was studied. In this way, pharmacogenetic predictors of adverse effects that patients can experience, and the need for dose adjustment based on the patient’s genotype, or individualizing the choice of alternative NSAIDs to increase the effectiveness of analgesia, have been determined.

Nicotinamide and WLDS Act Together to Prevent Neurodegeneration in Glaucoma.

Glaucoma is a complex neurodegenerative disease characterized by progressive visual dysfunction leading to vision loss. Retinal ganglion cells are the primary affected neuronal population, with a critical insult damaging their axons in the optic nerve head. This insult is typically secondary to harmfully high levels of intraocular pressure (IOP). We have previously determined that early mitochondrial abnormalities within retinal ganglion cells lead to neuronal dysfunction, with age-related declines in NAD (NAD+ and NADH) rendering retinal ganglion cell mitochondria vulnerable to IOP-dependent stresses. The Wallerian degeneration slow allele, WldS, decreases the vulnerability of retinal ganglion cells in eyes with elevated IOP, but the exact mechanism(s) of protection from glaucoma are not determined. Here, we demonstrate that WldS increases retinal NAD levels. Coupled with nicotinamide administration (an NAD precursor), it robustly protects from glaucomatous neurodegeneration in a mouse model of glaucoma (94% of eyes having no glaucoma, more than WldS or nicotinamide alone). Importantly, nicotinamide and WldS protect somal, synaptic, and axonal compartments, prevent loss of anterograde axoplasmic transport, and protect from visual dysfunction as assessed by pattern electroretinogram. Boosting NAD production generally benefits major compartments of retinal ganglion cells, and may be of value in other complex, age-related, axonopathies where multiple neuronal compartments are ultimately affected.

Genetic determinants of metamizole metabolism modify the risk of developing anaphylaxis

Metamizole is a NSAID that has been banned in several countries because of its toxicity. It is often involved in selective hypersensitivity reactions and most hypersensitivity patients develop anaphylaxis. Metamizole is rapidly metabolized, and metabolic profiles are related to genetic factors. We analyzed whether genetic determinants of metamizole metabolism influence the risk of developing hypersensitivity in 265 patients diagnosed with hypersensitivity to metamizole and 362 healthy individuals who tolerated metamizole. Slow acetylation is associated with an increased risk of developing selective hypersensitivity to metamizole [odds ratio for slow alleles=2.17 (95% confidence interval=1.44-3.27); P=0.00016], and particularly anaphylaxis [odds ratio=4.77 (95% confidence interval=2.28-9.98); P=0.000006], with a significant gene-dose effect. The association was not identified in patients with cross-hypersensitivity. Cytochrome P450 2C9 (CYP2C9) and cytochrome P450 2C19 (CYP2C19) genotypes did not influence risk association. Our findings raise the hypothesis of genetically determined metabolic variability as a risk factor for developing anaphylaxis with metamizole.

Influence of genetic polymorphisms of styrene-metabolizing enzymes on the levels of urinary biomarkers of styrene exposure

Styrene exposure is still present in different occupational settings including manufacture of synthetic rubber, resins, polyesters and plastic. The aim of this work was to investigate the effects of polymorphic genes CYP2E1, EPHX1, GSTT1, and GSTM1 on the urinary concentrations of the styrene metabolites mandelic acid (MA), phenylglyoxylic acid (PGA) and on the concentration ratios between (MA+PGA) and urinary styrene (U-Sty) and airborne styrene (A-Sty), in 30 workers from two fiberglass-reinforced plastic manufacturing plants and 26 unexposed controls. Personal air sampling and biological monitoring results revealed that sometimes exposure levels exceeded both the threshold limit value (TLV) and the biological exposure index (BEI) suggested by the American Conference of Governmental Industrial Hygienists. A significantly reduced excretion of styrene metabolites (MA+PGA) in individuals carrying the CYP2E1*5B and CYP2E1*6 heterozygote alleles, with respect to the homozygote wild type, was observed only in the exposed group. A reduction was also detected, in the same group, in subjects carrying the slow allele EPHX1 (codon 113), through the lowering of (MA+PGA)/urinary styrene concentration ratio. In addition, the ratio between MA+PGA and the personal airborne styrene concentration appeared to be modulated by the predicted mEH activity, in the exposed group, as evidenced by univariate linear regression analysis. Our results confirm some previous hypotheses about the role of the polymorphism of genes coding for enzymes involved in the styrene detoxification pathway: this may significantly reduce the levels of excreted metabolites and therefore it must be taken into account in the interpretation of the biological monitoring results for occupational exposure.

“Red Cell Complement Loading In PNH Patients On Eculizumab Is Associated With a C3 Polymorphism Which Influences C3 Function, Predicts For Increased Extravascular Hemolysis and Provides a Rationale For C3 Inhibition.”

IntroductionParoxysmal nocturnal hemoglobinuria (PNH) is an acquired bone marrow disorder characterised by intravascular hemolysis and hemoglobinuria, potentially life-threatening thrombosis and an association with aplastic anemia. Most of the clinical features and complications of PNH are due to the unopposed activity of complement due to the absence of CD59 and CD55, two key regulators of complement. Eculizumab prevents the cleavage of C5 complement thereby preventing terminal complement activity and protecting PNH cells from lysis. The inhibition of C5 preserves the early part of complement pathway and leads to the build up of C3 on the PNH red cells, perhaps in part due to their lack of CD55. The majority of PNH patients receiving eculizumab have evidence of extravascular haemolysis that can be clinically significant, including with anemia, hyperbilirubinemia and in some a continued requirement for transfusions. This extravascular hemolysis in thought to be due to the C3 loading of PNH red cells. MethodsWe report the C3-loading of the PNH red cells from 119 patients treated with eculizumab and correlate this with hemoglobin, LDH, bilirubin, reticulocytes and transfusions. We have studied genetic polymorphisms that affect both C3 and FCγR. We have genotyped 46 eculizumab patients for a functional mutation in the C3 gene (rs2230199). The two alleles of this gene can be distinguished by the presence or absence of a HindIII restriction site that distinguishes the electophoretically slow (arg80) from the electrophoretically fast (gly80) allotype. The fast (C3F) allotype allele of this snp is associated with a range of disorders including age-related macular degeneration, IgA nephropathy, systemic vasculitis and partial lipodystrophy. APL-1 is a small cyclic peptide that binds to and inhibits the activation of complement C3. APL-2 is a large conjugate of APL-1 with enhanced bioactivity and a long systemic half-life. APL-1 and APL-2 molecules as well as other complement inhibitors were studied for lysis of red cells and C3 loading in vitro in a modified Ham test in which flow cytometry was used to identify non-lysed cells. ResultsOut of the 119 Eculizumab treated patients, 55 (46.2%) required at least one transfusion on treatment. 110 patients had C3 detectable by flow cytometry on their PNH red cells (mean of 19.8%; range: <0.1 to 64.6%). C3-loading was not seen on the normal red cells from the same patients on treatment nor on the PNH red cells in patients not receiving eculizumab. The mean LDH (735IU/l) and reticulocyte count (193 x 109/l) were not statistically significantly different for the transfused group compared to the non-transfused group (518 and 163 respectively). Mean PNH C3 and RBC C3 did not differ stastistically between the transfused and non-transfused groups (26.20 Vs 24.78 PNH C3;15.96 vs 15.09 RBC C3 respectively).We studied one functional polymorphism in the Fcγ receptor but this showed no correlation with haemolytic parameters. Conversely, for the C3 polymorphism eculizumab-treated patients homozygous for the slow (C3S) allele had a significantly higher degree of C3 loading on PNH red blood cells with C3S/C3S having a mean of 33.7% C3 loaded PNH red cells (n=26), C3S/C3F 19.0% (n=19) and C3F/C3F 12.8% (n=3)(all P<0.01). Homozygote C3S also had increased reticulocytes (P<0.01) and bilirubin (P<0.01). The C3S allele has previously been shown to be more efficient in a haemolysis assay using sheep erythrocytes. This polymorphism appears to explain much of the variation in C3 loading between different patients with PNH.In vitro experiments show that inhibitors of C5, such as eculizumab, protect the PNH red cells from lysis but lead to a very rapid deposition of C3 on the PNH red cells. However both APL1 and APL2 demonstrated similar protection of PNH red cell lysis with virtually no C3 loading on PNH red cells. ConclusionA significant proportion of patients on eculizumab experience extravascular haemolysis with the majority of patients developing C3 loading. We show for the first time that a functional polymorphism in the C3 gene is associated parameters of hemolysis. The S(low) allele alters the function of C3 protein and appears to be associated with extravascular haemolysis in patients with PNH. The C3 inhibitors, APL-1 and APL-2, protect PNH red cells and prevent C3 loading in vitro and if safe to be given chronically would be expected to reduce extravascular hemolysis significantly. Disclosures:Hill:Alexion Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kelly:Alexion: Honoraria. Richards:Alexion Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hillmen:Alexion: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Variation in PAH-related DNA adduct levels among non-smokers: the role of multiple genetic polymorphisms and nucleotide excision repair phenotype.

Polycyclic aromatic hydrocarbons (PAHs) likely play a role in many cancers even in never-smokers. We tried to find a model to explain the relationship between variation in PAH-related DNA adduct levels among people with similar exposures, multiple genetic polymorphisms in genes related to metabolic and repair pathways, and nucleotide excision repair (NER) capacity. In 111 randomly selected female never-smokers from the Golestan Cohort Study in Iran, we evaluated 21 SNPs in 14 genes related to xenobiotic metabolism and 12 SNPs in eight DNA repair genes. NER capacity was evaluated by a modified comet assay, and aromatic DNA adduct levels were measured in blood by32P-postlabeling. Multivariable regression models were compared by Akaike's information criterion (AIC). Aromatic DNA adduct levels ranged between 1.7 and 18.6 per 10(8) nucleotides (mean: 5.8 ± 3.1). DNA adduct level was significantly lower in homozygotes for NAT2 slow alleles and ERCC5 non-risk-allele genotype, and was higher in the MPO homozygote risk-allele genotype. The sum of risk alleles in these genes significantly correlated with the log-adduct level (r = 0.4, p < 0.001). Compared with the environmental model, adding Phase I SNPs and NER capacity provided the best fit, and could explain 17% more of the variation in adduct levels. NER capacity was affected by polymorphisms in the MTHFR and ERCC1 genes. Female non-smokers in this population had PAH-related DNA adduct levels three to four times higher than smokers and occupationally-exposed groups in previous studies, with large inter-individual variation which could best be explained by a combination of Phase I genes and NER capacity.

Abstract A16: Genetic polymorphisms in the carcinogen metabolism pathway and lung cancer risk

Abstract Alterations affecting genes involved in the carcinogen metabolism are associated with cancer susceptibility since these can affect the detoxification capacity of the gene product. Genes regulating the carcinogen metabolism are also highly effective in the pathways involved in lung cancer development. The microsomal epoxide hydroxylase gene EPHX1 participates in the detoxification and activation of the carcinogenic compounds in the cigarette smoke. Two polymorphic changes in the EPHX1 gene result in slow and fast alleles with low and high enzyme activity. This differential effect suggests that these polymorphisms may affect individual lung cancer risk. Myeloperoxidase (MPO) is an oxidative enzyme released in response to cigarette smoke from the lung tissue. A G&amp;gt;A polymorphism located in the 5' untranslated region of the MPO gene that may be responsible for reduced transcriptional activity due to the decreased binding affinity for the SP1 transcription factor. In individuals carrying the A allele metabolic procarcinogen compounds are not effectively activated. Therefore, this variant is thought to play a protective role in lung cancer. The NAD(P)H dehydrogenase (NQO1) gene is an important mediator of lung cancer and codes for a cytoplasmic electron reductase which prevents the production of reactive radical species by detoxification of the quinones and their derivatives. Mutations in the NQO1 gene have been associated with susceptibility to various forms of cancer. A C to T substitution at codon 187 of the gene results in almost undetectable enzyme activity in the homozygote individuals carrying the variant allele. In this study we investigated the association of the EPHX1, MPO and NQO1 gene variants with lung cancer in 126 patients and 64 healthy individuals. Gene expression analysis was performed using the LightCycler 480 Real Time PCR system and hybridization probes. To analyze the genotypes the EPHX1, MPO and NQO1 genes were amplified by polymerase chain reaction and the presence of the gene variants was investigated by restriction fragment length polymorphism after digestion with specific restriction enzymes. No significant differences in the distribution of the genotypes and allele frequencies were observed between the patients and the control group for the MPO gene and the two different polymorphic variants of the EPHX1 gene. The NQO1 expression levels were higher in the patients when compared to the controls but the difference was not significant. On the other hand, a significant association was observed between the CC genotype and NQO1 expression. Citation Format: Nejat Dalay, Nur Buyru, Zubeyde Yalniz. Genetic polymorphisms in the carcinogen metabolism pathway and lung cancer risk. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A16.

Genotype Frequencies of Drug-Metabolizing Enzymes Responsible for Purine and Pyrimidine Antagonists in a Healthy Asian-Indian Population

Purine and pyrimidine antimetabolites are used to treat leukemias, autoimmune diseases, and solid tumors. Detection of slow metabolizers before administration of the drugs is necessary to prevent any subsequent drug toxicity. With this aim, we determined the frequencies of normal and slow alleles in our population. Polymorphisms in genes encoding cytidine deaminase (CDA), dihydropyrimidine dehydrogenase (DPYD), and thiopurine-S-methyltransferase (TPMT) were documented in 225 healthy volunteers. The polymorphisms typed included CDA*3, DPYD*2A, TPMT*2A, TPMT*3B, and TPMT*3C. Methods used for genotyping included standard PCR-RFLP and allele-specific PCR reactions. The frequencies were 0.44 % for DPYD*2A, 0.67 % for TPMT*3B, and 0.89 % for TPMT*3C. The CDA*3 and TPMT*2A alleles were not detected. Although these polymorphisms have been demonstrated to be associated with drug toxicity in other populations, they appear to be very rare in the adult Indian population.

Abstract 2646: Genetic determinants of PAH-DNA adduct level and nucleotide excision repair among non-smokers in a high risk area for esophageal squamous cell carcinoma

Abstract Background: Polycyclic aromatic hydrocarbons (PAHs) play a role in esophageal squamous cell carcinoma in high risk areas where even non-smokers are highly exposed to these compounds. Their early biological effect is the formation of DNA adducts, mediated by phase 1 and 2 pathways and nucleotide excision repair (NER). We aimed at finding a genetic model to explain inter-individual variations in PAH-DNA adduct level among people with similar exposures. Methods: In 111 randomly-selected female non-smokers from the Golestan Cohort Study in Iran, 21 SNPs in 14 genes related to xenobiotic metabolism and 13 SNPs in 9 DNA repair genes were studied (Table). NER capacity was evaluated by a comet assay, and DNA adduct level was measured by 32p-postlabelling. Multivariate regression was used to assess the effects of the number of risk alleles, NER capacity, and environmental exposures on the log-transformed PAH-DNA adduct levels. Models were compared by Akaike's information criterion (AIC). Results: Mean PAH-DNA adduct level was 5.76+3.13 per 108 nucleotides (range: 1.71 - 18.57). The level of PAH-DNA adducts was significantly lower in homozygotes for N-acetyltransferase 2 (NAT2) slow alleles and excision repair cross-complementing (ERCC)-5 T/T genotype, and higher in individuals with myeloperoxidase (MPO) G/G genotype. The sum of risk alleles in these genes had a significant correlation with the log-adduct level (r=0.4, p&amp;lt;0.001). The table shows gene level coefficients for multivariate analysis. The model including environmental exposures, phase 1 SNPs and NER capacity had the best fit (AIC=93.7). NER capacity itself was affected by a polymorphism in the methylenetetrahydrofolate reductase gene. Conclusion: We observed a high level of PAH-DNA adducts with great inter-individual variation, which could be best explained by a combination of environmental factors, number of polymorphisms in phase 1 genes and DNA repair capacity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2646. doi:1538-7445.AM2012-2646

N-acetyltransferase-2 (NAT2) Gene Polymorphisms and Enzyme Activity in Serbs: Unprecedented High Prevalence of Rapid Acetylators in a White Population

The aim of this study was to investigate N-acetyltransferase 2 (NAT2) genetic polymorphism and enzyme activity in Serbs, and to examine the influence of NAT2 genotype, sex, and smoking on the phenotype. Genotyping for 190C>T, 282C>T, 341T>C, 403C>G, 411T>A, 481C>T, 590G>A, 803A>G, and 857G>A in the NAT2 gene, was performed in 140 healthy Serbs. NAT2 activity was determined as AFMU/ (AFMU + 1X + 1U) urinary ratio in 100 subjects using caffeine as a probe. The most frequent NAT2 haplotypes were NAT2*5B (38.2%), NAT2*6A (26.0%), and NAT2*4 (24.4%). The log-transformed NAT2 activity indices exhibited trimodal distribution with 9%, 36%, and 55% of slow, intermediate, and rapid acetylators, respectively. Significant NAT2 genotype-phenotype correlation was observed (P < .0001). The frequency of NAT1*10 and NAT1*11 were 27.5% and 6.9%, respectively. There was no significant influence of sex or cigarette smoking on NAT2 enzyme activity. Eight subjects displayed rapid NAT2 acetylators phenotype despite being homozygous for NAT2 slow alleles, and NAT1 fast acetylators genotype (NAT1*10 and NAT1*11) had no implication. In contrast to other white populations described hitherto, rapid acetylator is the predominant NAT2 phenotype in Serbs. NAT2 genotype, but not sex and cigarette smoking, influence enzyme activity. NAT1 fast acetylators genotypes do not contribute for NAT2 genotype-phenotype discordance.

Codominant Expression ofN-Acetylation andO-Acetylation Activities Catalyzed byN-Acetyltransferase 2 in Human Hepatocytes

Human populations exhibit genetic polymorphism in N-acetylation capacity, catalyzed by N-acetyltransferase 2 (NAT2). We investigated the relationship between NAT2 acetylator genotype and phenotype in cryopreserved human hepatocytes. NAT2 genotypes determined in 256 human samples were assigned as rapid (two rapid alleles), intermediate (one rapid and one slow allele), or slow (two slow alleles) acetylator phenotypes based on functional characterization of the NAT2 alleles reported previously in recombinant expression systems. A robust and significant relationship was observed between deduced NAT2 phenotype (rapid, intermediate, or slow) and N-acetyltransferase activity toward sulfamethazine (p < 0.0001) and 4-aminobiphenyl (p < 0.0001) and for O-acetyltransferase-catalyzed metabolic activation of N-hydroxy-4-aminobiphenyl (p < 0.0001), N-hydroxy-2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (p < 0.01), and N-hydroxy-2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (p < 0.0001). NAT2-specific protein levels also significantly associated with the rapid, intermediate, and slow NAT2 acetylator phenotypes (p < 0.0001). As a negative control, p-aminobenzoic acid (an N-acetyltransferase 1-selective substrate) N-acetyltransferase activities from the same samples did not correlate with the three NAT2 acetylator phenotypes (p > 0.05). These results clearly document codominant expression of human NAT2 alleles resulting in rapid, intermediate, and slow acetylator phenotypes. The three phenotypes reflect levels of NAT2 protein catalyzing both N- and O-acetylation. Our results suggest a significant role of NAT2 acetylation polymorphism in arylamine-induced cancers and are consistent with differential cancer risk and/or drug efficacy/toxicity in intermediate compared with rapid or slow NAT2 acetylator phenotypes.

Transcriptome Profiling of Embryonic Development Rate in Rainbow Trout Advanced Backcross Introgression Lines

In rainbow trout (Oncorhynchus mykiss) and other fishes, embryonic development rate is an ecologically and evolutionarily important trait that is closely associated with survival and physiological performance later in life. To identify genes differentially regulated in fast and slow-developing embryos of rainbow trout, we examined gene expression across developmental time points in rainbow trout embryos possessing alleles linked to a major quantitative trait loci (QTL) for fast versus slow embryonic development rate. Whole genome expression microarray analyses were conducted using embryos from a fourth generation backcross family, whereby each backcross generation involved the introgression of the fast-developing alleles for a major development rate QTL into a slow-developing clonal line of rainbow trout. Embryos were collected at 15, 19, and 28days post-fertilization; sex and QTL genotype were determined using molecular markers, and cDNA from 48 embryos were used for microarray analysis. A total of 183 features were identified with significant differences between embryonic development rate genotypes. Genes associated with cell cycle growth, muscle contraction and protein synthesis were expressed significantly higher in embryos with the fast-developing allele (Clearwater) than those with the slow-developing allele (Oregon State University), which may associate with fast growth and early body mass construction in embryo development. Across time points, individuals with the fast-developing QTL allele appeared to have earlier onset of these developmental processes when compared to individuals with the slow development alleles, even as early as 15days post-fertilization. Differentially expressed candidate genes chosen for linkage mapping were localized primarily to regions outside of the major embryonic development rate QTL, with the exception of a single gene (very low-density lipoprotein receptor precursor).

Aromatic DNA adducts and polymorphisms in metabolic genes in healthy adults: findings from the EPIC-Spain cohort

Aromatic compounds such as polycyclic aromatic hydrocarbons, arylamines and heterocyclic amines require metabolic activation to form metabolites able to bind to DNA, a process mediated by polymorphic enzymes. We measured aromatic DNA adducts in white blood cells by the (32)P-post-labelling assay in a sample of 296 healthy adults (147 men and 149 women) from five regions of Spain. We also analyzed functional polymorphisms in the metabolic genes CYP1A1, CYP1A2, EPHX1, GSTM1, GSTT1, NAT2 and SULT1A1. A significant increased level of DNA aromatic adducts was found related to the fast oxidation-hydrolysis phenotype defined by the polymorphism I462V in CYP1A1, the allele A in IVS1-154C>A of CYP1A2 and the combination Tyrosine-Arginine for Y113H and H139R of EPHX1. Geometric means (adducts per 10(-9) normal nucleotides) were 2.17, 4.04 and 6.30 for slow, normal and fast phenotypes, respectively (P-trend = 0.01). Slow acetylation by NAT2 was associated with a significant decrease in adduct level; subjects with slow alleles *5A and *7A/B had in average 1.56 x 10(-9)adducts, as compared with 5.60 for those with normal NAT2 activity (P-value = 0.01). No association was seen with polymorphisms of other metabolic genes such as GSTM1, GSTT1 or SULT1A1. We concluded that the metabolic pathways of oxidation, hydrolysis and acetylation are relevant to the formation of bulky DNA adducts. This could suggest a potential involvement of aromatic compounds in the formation of such adducts; however, given lack of specificity of the post-labeling assay, a firm conclusion cannot be drawn.

Haplotype ofN-Acetyltransferase 1 and 2 and Risk of Pancreatic Cancer

We examined the association between N-acetyltransferase 1 and 2 (NAT1 and NAT2) haplotype and risk of pancreatic cancer by genotyping eight NAT1 and seven NAT2 single nucleotide polymorphisms in 532 patients and in 581 healthy controls (all non-Hispanic white) who were recruited at M. D. Anderson Cancer Center from January 2000 to December 2006. Haplotypes were reconstructed by using an expectation-maximization algorithm. Odds ratios and 95% confidence intervals were estimated by using unconditional logistic regression models. Covariates included age (continuous variable), sex, pack-year of smoking (categorical), and history of diabetes when appropriate. NAT1 and NAT2 genotype was mutually adjusted. The prevalence of haplotype NAT1*10-NAT2*6A was 4.3% versus 2.7% (P=0.06) and NAT1*11-NAT2*6A was 1.2% versus 0.4% (P=0.05) in patients and controls, respectively. The diplotype NAT1*10/*10 or NAT1*10/*11 and NAT2*6A/any slow allele was associated with a higher risk of pancreatic cancer compared with other diplotypes (multivariate odds ratio, 4.15; 95% confidence interval, 1.15-15.00; P=0.03). NAT2 slow genotype were associated with increased risk of pancreatic cancer among heavy smokers and among individuals with a history of diabetes. We for the first time found that rare NAT1*10 or NAT1*11-NAT2*6A diplotype may be an "at-risk" genetic variant for pancreatic cancer. The NAT2*6A/any slow acetylation genotype may be a predisposing factor for pancreatic cancer among diabetics with smoking exposure. Our observations must be confirmed in larger independent studies.

Analysis of NAT2 point mutations with biological microchips

The NAT2 product, N-acetyltransferase 2, is involved in biotransformation and detoxification of several aromatic amines (in particular, 2-aminofluorene, 4-aminobiphenyl, and 4-naphthylamine), which are strongly mutagenic and carcinogenic, and acetylates some drugs, affecting their metabolism. A biological microchip was developed to detect 16 point mutations, which determine 36 alleles and 660 genotypes of NAT2. The genotypes can be divided into four groups according to the acetylator phenotype: groups with rapid (R/R), intermediate (R/S), or slow (S/S) acetylation and a group combining intermediate and slow alleles (“R/S or S/S”). The last group includes the alleles determined by combinations of seven mutations (191G/A, 282C/T, 341T/C, 481C/T, 590G/A, 803A/G, and 857G/A), whose cis or trans position is detectable by restriction enzyme analysis. The NAT2 genotype was unequivocally established for 37 out of 71 DNA specimens, while the other 34 specimens were characterized by more than two genotypes. By the acetylator phenotype, 16 out of the 34 genotypes were assigned to the group “R/S or S/S,” combining mutations 282C/T, 341T/C, 481C/T, 590G/A, and 803A/G. Thus, the biochip allows primary analysis of most NAT2 polymorphic substitutions, the acetylator genotype being important to know in predictive medicine and individualized therapy.