N-acetyltransferase 2 Activity Research Articles

Human N-acetyltransferase 2 (NAT2) gene variability in Brazilian populations from different geographical areas.

Introduction: Several polymorphisms altering the NAT2 activity have already been identified. The geographical distribution of NAT2 variants has been extensively studied and has been demonstrated to vary significantly among different ethnic population. Here, we describe the genetic variability of human N-acetyltransferase 2 (NAT2) gene and the predominant genotype-deduced acetylation profiles of Brazilians. Methods: A total of 964 individuals, from five geographical different regions, were genotyped for NAT2 by sequencing the entire coding exon. Results: Twenty-three previously described NAT2 single nucleotide polymorphisms (SNPs) were identified, including the seven most common ones globally (c.191G>A, c.282C>T, c.341T>C, c.481C>T, c.590G>A, c.803A>G and c.857G>A). The main allelic groups were NAT2*5 (36%) and NAT2*6 (18.2%), followed to the reference allele NAT2*4 (20.4%). Combined into genotypes, the most prevalent allelic groups were NAT2*5/*5 (14.6%), NAT2*5/*6 (11.9%) and NAT2*6/*6 (6.2%). The genotype deduced NAT2 slow acetylation phenotype was predominant but showed significant variability between geographical regions. The prevalence of slow acetylation phenotype was higher in the Northeast, North and Midwest (51.3%, 45.5% and 41.5%, respectively) of the country. In the Southeast, the intermediate acetylation phenotype was the most prevalent (40.3%) and, in the South, the prevalence of rapid acetylation phenotype was significantly higher (36.7%), when compared to other Brazilian states (p < 0.0001). Comparison of the predicted acetylation profile among regions showed homogeneity among the North and Northeast but was significantly different when compared to the Southeast (p = 0.0396). The Southern region was significantly different from all other regions (p < 0.0001). Discussion: This study contributes not only to current knowledge of the NAT2 population genetic diversity in different geographical regions of Brazil, but also to the reconstruction of a more accurate phenotypic picture of NAT2 acetylator profiles in those regions.

Application of a physiologically based pharmacokinetic model to predict isoniazid disposition during pregnancy.

Pregnancy can increase the risk of latent tuberculosis infection (LTBI) progression to tuberculosis (TB) disease. Isoniazid (INH) is the preferred preventative treatment for LTBI in pregnancy. INH is mainly cleared by N-acetyltransferase 2 (NAT2) but the pharmacokinetics (PK) of INH in different NAT2 phenotypes during pregnancy is not well characterized. To address this knowledge gap, we used physiologically based pharmacokinetic (PBPK) modeling to evaluate NAT2 phenotype-specific effects of pregnancy on INH disposition. A whole-body PBPK model for INH was developed and verified for non-pregnant NAT2 fast (FA), intermediate (IA), and slow (SA) acetylators. Model predictive performance was assessed using a drug-specific model acceptance criterion for mean plasma area under the curve (AUC) and peak plasma concentration (Cmax ), and the absolute average fold error (AAFE) for individual plasma concentrations. The verified model was extended to simulate INH disposition during pregnancy in NAT2 SA, IA, and FA populations. A sensitivity analysis was conducted using the verified PBPK model and known changes in INH disposition during pregnancy to determine whether NAT2 activity changes during pregnancy or other INH clearance pathways are altered. This analysis suggested that NAT2 activity is unchanged while other INH clearance pathways increase by ~80% during pregnancy. The model was applied to explore the effect of pregnancy on INH disposition in two ethnic populations with different NAT2 phenotype distributions and with high TB burden. Our PBPK model can be used to predict INH disposition during pregnancy in diverse populations and expanded to other drugs cleared by NAT2 during pregnancy.

N -acetyltransferase 2 haplotype modifies risks for both dyslipidemia and urinary bladder cancer.

A novel haplotype in N -acetyltransferase 2 ( NAT2 ) composed of seven non-coding variants (rs1495741, rs4921913, rs4921914, rs4921915, rs146812806, rs35246381, and rs35570672) has been linked to dyslipidemia by multiple, independent genome-wide association studies. The haplotype is located approximately 14 kb downstream of NAT2-coding region (ch8:18,272,377-18,272,881; GRCh38/hg38) and represents a non-coding, intergenic haplotype. Interestingly, the same dyslipidemia NAT2 haplotype is also linked to urinary bladder cancer risk. Dyslipidemia risk alleles are associated with rapid acetylator phenotype, whereas bladder cancer risk alleles are associated with slow acetylator, suggesting that the level of systemic NAT2 activity modifies the risk of these pathologies. We speculate that rs1495741 (and its associated haplotype) belongs to a distal regulatory element of human NAT2 gene (e.g., enhancer or silencer), and the genetic variation at the newly discovered haplotype results in a differential level of NAT2 gene expression. Understanding how this NAT2 haplotype contributes to not only urinary bladder cancer but also to dyslipidemia will ultimately help devise strategies to identify and protect susceptible individuals.

Non-coding and intergenic genetic variants of human arylamine N-acetyltransferase 2 (NAT2) gene are associated with differential plasma lipid and cholesterol levels and cardiometabolic disorders.

Arylamine N-acetyltransferase 2 (NAT2) is a phase II metabolic enzyme, best known for metabolism of aromatic amines and hydrazines. Genetic variants occurring in the NAT2 coding region have been well-defined and are known to affect the enzyme activity or protein stability. Individuals can be categorized into rapid, intermediate, and slow acetylator phenotypes that significantly alter their ability to metabolize arylamines, including drugs (e.g., isoniazid) and carcinogens (e.g., 4-aminobiphenyl). However, functional studies on non-coding or intergenic variants of NAT2 are lacking. Multiple, independent genome wide association studies (GWAS) have reported that non-coding or intergenic variants of NAT2 are associated with elevated plasma lipid and cholesterol levels, as well as cardiometabolic disorders, suggesting a novel cellular role of NAT2 in lipid and cholesterol homeostasis. The current review highlights and summarizes GWAS reports that are relevant to this association. We also present a new finding that seven, non-coding, intergenic NAT2 variants (i.e., rs4921913, rs4921914, rs4921915, rs146812806, rs35246381, rs35570672, and rs1495741), which have been associated with plasma lipid and cholesterol levels, are in linkage disequilibrium with one another, and thus form a novel haplotype. The dyslipidemia risk alleles of non-coding NAT2 variants are associated with rapid NAT2 acetylator phenotype, suggesting that differential systemic NAT2 activity might be a risk factor for developing dyslipidemia. The current review also discusses the findings of recent reports that are supportive of the role of NAT2 in lipid or cholesterol synthesis and transport. In summary, we review data suggesting that human NAT2 is a novel genetic factor that influences plasma lipid and cholesterol levels and alters the risk of cardiometabolic disorders. The proposed novel role of NAT2 merits further investigations.

Fluorescence-based visual analysis and inhibitor screening of Arylamine N-acetyltransferase 2, a key enzyme for tuberculosis

Tuberculosis is a global epidemic caused by pathogenic Mycobacterium tuberculosis (Mtb), which seriously threatens human life. Arylamine N-acetyltransferase 2 (NAT2) is a vital enzyme in the synthesis of Mtb wall, and closely related to the growth of Mtb. Herein, a fluorescence-based recognition tool (BDPN) has been developed for rapid, sensitive, and selective detection of NAT2 activity in Mtb. As well as a visual high-throughput screening approach for NAT2 inhibitors was established based on BDPN, and four active natural compounds derived from Psoraleae Fructus were discovered that exhibited strong inhibitory effect toward NAT2. Furthermore, Isobavachalcone exhibited the considerable anti-tuberculosis effect through prominently destroying the bacterial cell wall of Mtb and slow down its growth. Moreover, Isobavachalcone could delay the elimination of the anti-tuberculosis drug Isoniazid (INH) mediated by NAT2 and enhance anti-tuberculosis effect of INH. In summary, BDPN was a promising tool for monitoring endogenous NAT2 in Mtb and provided some useful guidance for the rational administration of anti-tuberculosis drug.

N-acetyltransferase 2 acetylator genotype-dependent N-acetylation and toxicity of the arylamine carcinogen β-naphthylamine in cryopreserved human hepatocytes.

We used cryopreserved human hepatocytes that express rapid, intermediate, and slow acetylator N-acetyltransferase 2 (NAT2) genotypes to measure the N-acetylation of β-naphthylamine (BNA) which is one of the aromatic amines found in cigarette smoke including E-cigarettes. We investigated the role of NAT2 genetic polymorphism in genotoxicity and oxidative stress induced by BNA. In vitro BNA NAT2 activities in rapid acetylators was 1.6 and 3.5-fold higher than intermediate (p &lt; 0.01) and slow acetylators (p &lt; 0.0001). BNA N-acetylation in situ was 3 to 4- fold higher in rapid acetylators than slow acetylators, following incubation with 10 and 100µM BNA (p &lt; 0.01). DNA damage was two to threefold higher in the rapid versus slow acetylators (p &lt; 0.0001) and 2.5-fold higher in intermediate versus slow acetylators following BNA treatment at 100 and 1000μM, ROS/RNS level was the highest in rapid acetylators followed by intermediate and then slow acetylators (p &lt; 0.0001). Our findings show that theN-acetylation of BNA is NAT2 genotype dependent in cryopreserved human hepatocytes and our data further document an important role for NAT2 genetic polymorphism in modifying BNA-induced genotoxicity and oxidative damage.

Enhanced cytotoxicity of a novel family of ATPase inhibitors in colorectal cancer cells with high NAT2 activity

Loss of heterozygosity (LOH) is a hallmark feature of cancer genomes that reduces allelic variation, thereby creating tumor specific vulnerabilities which could be exploited for therapeutic purposes. We previously reported that loss of drug metabolic arylamine N-acetyltransferase 2 (NAT2) activity following LOH at 8p22 could be targeted for collateral lethality anticancer therapy in colorectal cancer (CRC). Here, we report a novel compound CBK034026C that exhibits specific toxicity towards CRC cells with high NAT2 activity. Connectivity Map analysis revealed that CBK034026C elicited a response pattern related to ATPase inhibitors. Similar to ouabain, a potent inhibitor of the Na+/K+-ATPase, CBK034026C activated the Nf-kB pathway. Further metabolomic profiling revealed downregulation of pathways associated with antioxidant defense and mitochondrial metabolism in CRC cells with high NAT2 activity, thereby weakening the protective response to oxidative stress induced by CBK034026C. The identification of a small molecule targeting metabolic vulnerabilities caused by NAT2 activity provides novel avenues for development of anticancer agents.

Expression of arylamine N-acetyltransferase 2 activity in immortalized human bronchial epithelial cells

Lung cancer is the leading cause of cancer deaths in the United States with high incidence in tobacco smokers. Arylamine N-acetyltransferase 2 (NAT2) is a xenobiotic enzyme that catalyzes both N- and O-acetylation of carcinogens present in tobacco smoke and contributes towards the genotoxicity of these carcinogens. NAT2 allelic variants result in slow, intermediate, and rapid acetylation phenotypes. A recent meta-analysis reported NAT2 non-rapid (slow and intermediate) phenotypes had a significantly increased risk of lung cancer. NAT2 activity in humans is thought to be restricted to liver and gastrointestinal tract, and no studies to our knowledge have reported the expression of NAT2 activity in immortalized human lung epithelial cells. Given the importance of NAT2 in cancer and inhalation of various carcinogens directly into the lungs, we investigated NAT2 activity in human lung epithelial cells. Both NAT1 and NAT2 protein were detected by “in-cell” Western. Arylamine N-acetyltransferase activity was determined with selective substrates for NAT1 (p-aminobenzoic acid; PABA) and NAT2 (sulfamethazine; SMZ) in the presence and absence of a selective NAT1 inhibitor. PABA N-acetylation (NAT1 activity) in cell protein lysates was abolished in the presence of 25 μM of NAT1 inhibitor whereas SMZ N-acetylation (NAT2) was unaffected. Incubation with the NAT1 inhibitor partially reduced the N-acetylation of β-naphthylamine and the O-acetylation of N-hydroxy-4-aminobiphenyl consistent with catalysis by both NAT1 and NAT2. Immortalized human lung epithelial cells exhibited dose-dependent N-acetylation of 4-ABP with an apparent KM of 24.4 ± 5.1 μM. These data establish that NAT2 is expressed and functional in immortalized human lung epithelial cells and will help us further our understanding of NAT2 in lung cancer.

Human arylamine N-acetyltransferase 2 genotype-dependent protein expression in cryopreserved human hepatocytes

Human N-acetyltransferases (NAT; EC 2.3.1.5) catalyze the N-acetylation of arylamine and hydrazine drugs and the O-acetylation of N-hydroxylated metabolites of aromatic and heterocyclic amines. Two different isoforms of this protein, N-acetyltransferase 1 (NAT1) and N-acetyltransferase 2 (NAT2), are expressed in human hepatocytes. Both are encoded by a single 870-bp open reading frame that exhibits genetic polymorphisms in human populations. NAT1 and NAT2 share more than 85% gene and protein sequence, making it challenging to produce antibodies with high specificity for NAT1 or NAT2. In the present study, we compared methods for the quantification of immunoreactive NAT1 and NAT2 with seven different antibodies and investigated the relationship of NAT2 genotype to NAT2 mRNA and protein expression in cryopreserved human hepatocytes. Sulfamethazine (NAT2-selective substrate) and NAT2 protein expression differed significantly with NAT2 acetylator genotype (p < 0.0001). NAT2 protein expression and sulfamethazine NAT2 catalytic activity correlated highly across the cryopreserved human hepatocytes of rapid, intermediate, and slow acetylator NAT2 genotypes. In conclusion, our data describe a specific analytical method for the quantification of NAT1 and NAT2 protein expression. We showed that the NAT2 activity in human hepatocytes is directly correlated to expression levels of NAT2 protein but not mRNA.

Establishing the Genotyping Method for NAT2 Polymorphism in Vietnamese Tuberculoma Patients

The metabolism of Isoniazid, one of the first-line antituberculosis drugs for TB treatment and prophylaxis, depends on the acetyltransferase 2 acetylation (NAT2) phenotype. Different phenotypes of NAT2 will lead to differences in drug concentration and the risk of uncontrolled side effects, such as hepatitis, peripheral neuropathy, gastrointestinal disorders (nausea, vomiting, and stomach pain). These risks are related to the presence of mutant NAT2 alleles such as NAT2*5 (c.341T&gt; C), *6 (c.590G&gt; A) and *7 (c.857G&gt; A), that reduce the N- acetyltransferase activity. Therefore, the genotyping method for NAT2 polymorphism using RFLP and Sanger sequencing was established. The method was successfully applied to determine the polymorphism of 84 TB patients. This study provides a better tool for analyzing NAT2 gene to assist clinicians in treating isoniazid.&#x0D; Keywords&#x0D; Enzyme NAT2, isoniazid, single nucleotide polymorphism, RFLP, Sanger sequencing.&#x0D; References&#x0D; [1] U.A. Boelsterli, K.K. Lee, Mechanisms of isoniazid-induced idiosyncratic liver injury: emerging role of mitochondrial stress, J. Gastroenterol. Hepatol. 29 (2014) 678–687.[2] A. Zabost, S. Brzezinska, M. Kozinska, M. Blachnio, J. Jagodzinski, Z. Zwolska, E. Augustynowicz-Kopec, Correlation of N-acetyltransferase 2 genotype with isoniazid acetylation in Polish tuberculosis patients, Biomed Res Int. 2013 (2013) 1-5.[3] M. Kinzig-Schippers, D. Tomalik-Scharte, A. Jetter, B. Scheidel, V. Jakob, M. Rodamer, I. Cascorbi, O. Doroshyenko, F. Sorgel, U. Fuhr, Should we use N-acetyltransferase type 2 genotyping to personalize isoniazid doses? Antimicrob Agents Chemother. 49 (2005) 1733-8[4] K. Walker, G. Ginsberg, D. Hattis, D.O. Johns, K.Z. Guyton, B. Sonawane, Genetic polymorphism in N-Acetyltransferase (NAT): Population distribution of NAT1 and NAT2 activity, J Toxicol Environ Health B Crit Rev. 12 (2009) 440-472. [5] G. Ramachandran, S. Swaminathan, Role of pharmacogenomics in the treatment of tuberculosis: a review, Pharmgenomics Pers Med. 5 (2012) 89-98.[6] J. Azuma, M. Ohno, R. Kubota, S. Yokota, T. Nagai, K. Tsuyuguchi, Y. Okuda, T. Takashima, S. Kamimura, Y. Fujio, I. Kawase, Pharmacogenetics-based tuberculosis therapy research group, NAT2 genotype guided regimen reduces isoniazid-induced liver injury and early treatment failure in the 6-month four-drug standard treatment of tuberculosis: a randomized controlled trial for pharmacogenetics-based therapy, Eur J Clin Pharmacol. 69 (2013) 1091-1101.[7] P.S. Adole, P.S. Kharbanda, S. Sharma, N-acetyltransferase 2 (NAT2) gene polymorphism as a predisposing factor for phenytoin intoxication in tuberculous meningitis or tuberculoma patients having seizures - A pilot study, Indian J Med Res. 143 (2016) 581-590.[8] WHO Scientific Group on Pharmacogenetics and World Health Organization, Pharmacogenetics: report of a WHO scientific group,World Health Organization Technical Report Series. (1973)[9] T.D. Da Silva, A.V. Felipe, J.M. De Lima, C.T. Oshima, N.M. Forones, N-Acetyltransferase 2 genetic polymorphisms and risk of colorectal cancer, World J Gastroenterol. 17 (2011) 760-765. [10] E.Y. Lau, J.S. Felton, F.C. Lightstone, Insights into the o-acetylation reaction of hydroxylated heterocyclic amines by human arylamine N-acetyltransferases: a computational study, Chem Res Toxicol. 19 (2006) 182-1190.[11] Ensembl - EBI, http://asia.ensembl.org/Homo_sapiens/Variation/Population?db=core;r=8:18399844-18400844;v=rs1801280;vdb=variation;vf=1243314,2019 (Ensembl release 96 - April 2019).[12] I.B. Kuznetsov, M. McDuffie, R. Moslehi, A web server for inferring the human N-acetyltransferase-2 (NAT2) enzymatic phenotype from NAT2 genotype, Bioinformatics. 25 (2009) 1185-1186. [13] P. Wang, K. Pradhan, X.B. Zhong, X. Ma, Isoniazid metabolism and hepatotoxicity, Acta Pharm Sin B. 6 (2016) 384-392.[14] M. Ohno, I. Yamaguchi, I. Yamamoto, T. Fukuda, S. Yokota, Slow N-acetyltransferase 2 genotype affects the incidence of isoniazid and rifampicin-induced hepatotoxicity, Int J Tuberc Lung Dis. 4 (2000) 256-261. [15] G.M. Lower, T. Nilsson, C.E. Nelson, H. Wolf, T.E. Gamsky, G.T. Bryan, N-acetyltransferase phenotype and risk in urinary bladder cancer: approaches in molecular epidemiology. Preliminary results in Sweden and Denmark, Int J Epidemiol. 36 (2007) 11-18.&#x0D; &#x0D; &#x0D;

Alterations in Xenobiotic-Metabolizing Enzyme Activities across Menstrual Cycle in Healthy Volunteers.

The purpose of the study was to determine whether the in vivo activities of drug-metabolizing enzymes CYP1A2 and CYP2A6, xanthine oxidase (XO), and N-acetyltransferase-2 (NAT2) vary across the menstrual cycle. Forty-two healthy women were studied at early follicular phase (EFP: 2nd to 4th days), late follicular phase (LFP: 10th to 12th days), and luteal phase (LP: 19th to 25th days) of a single menstrual cycle, and blood and urine samples were collected at each phase. Spot urine samples obtained 6 hours following 200-mg caffeine administration were used to determine caffeine metabolite ratios (CMRs); blood samples were used to determine CYP1A2*1F (rs762551) and CYP1A2*1C (rs2069514) polymorphisms and the hormonal profile (estradiol, progesterone, and luteinizing and follicle-stimulating hormones) at EFP, LFP, and LP. CMR and hormone variations were analyzed at three levels (EFP, LFP, LP) using one-way repeated-measures analysis of variance. CYP1A2 activity was lower and that of CYP2A6 and NAT2 were higher at LFP compared with EFP and LP. Enzyme alterations were significant in volunteers (n = 21) whose hormonal profiles at EFP, LFP, and LP corresponded to expected levels, but not in volunteers (n = 15) with presumed early or late sampling around LFP. No significant difference was detected in any enzyme activity in presumed anovulatory volunteers (n = 6). The reduction of CYP1A2 activity at LFP was not associated with smoking or CYP1A2*1F polymorphism. XO and NAT2 (fast acetylators) activities remained unaltered. It is suggested that drug-metabolizing enzyme activities are altered across the menstrual cycle. Selection of appropriate sampling periods verified by hormonal assessment and identification of anovulatory cycles are decisive factors in disclosing altered enzyme activity across the menstrual cycle.

Effects of microRNA-217 on proliferation, apoptosis, and autophagy of hepatocytes in rat models of CCL4-induced liver injury by targeting NAT2.

Liver injury is an important cause of serious liver disease. This study aims to explore the effects of miR-217 targeting NAT2 on hepatocyte proliferation, apoptosis, and autophagy following carbon tetrachloride (CCL4)-induced liver injury. Rat models of CCL4-induced liver injury were established. Healthy Wistar rats were randomized into the normal, blank, negative control (NC), microRNA-217 (miR-217) mimic, miR-217 inhibitor, small interfering RNA (siRNA)-N-acetyltransferase 2 (NAT2), and miR-217 inhibitor + siRNA-NAT2 groups. NAT2 activity was evaluated with reversed-phase high-performance liquid chromatographic method.Immunohistochemistry was used to detect NAT2 protein positive rate. Reverse transcription quantitative polymerase chain reaction and western blot analysis were used to examine expressions of miR-217, NAT2, Bcl-2, Bax, p35, LC3-II, Becline-1, and the ratio of caspase-3/cleaved caspase-3. Autophagy, proliferation, and cell cycle distribution were determined by electron microscope, CCK-8, and flow cytometry. NAT2 protein positive rate and miR-217, NAT2, Bcl-2, and p35 expressions were higher and Bax, LC3-II, and Becline-1 expressions and the ratio of caspase-3/cleaved caspase-3 lower in the normal group than the other six groups. Compared with the blank and NC groups, in the miR-217 mimic and siRNA-NAT2 groups, Bax, LC3-II, and Becline-1 expressions and the ratio of caspase-3/cleaved caspase-3, and hepatocyte apoptosis and autophagy increased, while NAT2, Bcl-2, and p35 expressions and hepatocyte proliferation decreased; opposite results were observed in the miR-217 inhibitor group. Collectively, miR-217 targeting NAT2 inhibits proliferation and promotes apoptosis and autophagy of hepatocytes in CCL4-induced liver injury.

Heritability of Caffeine Metabolism: Environmental Effects Masking Genetic Effects on CYP1A2 Activity but Not on NAT2.

Heritability of caffeine pharmacokinetics and cytochrome P450 1A2 (CYP1A2) activity is controversial. Here, we analyzed the pharmacokinetics of caffeine, an in vivo probe drug for CYP1A2 and arylamine N-acetyltransferase 2 (NAT2) activity, in monozygotic (MZ) and dizygotic (DZ) twins. In the entire group, common and unique environmental effects explained most variation in caffeine area under the curve (AUC). Apparently, smoking and hormonal contraceptives masked the genetic effects on CYP1A2 activity. However, when excluding smokers and users of hormonal contraceptives, 89% of caffeine AUC variation was due to genetic effects and, even in the entire group, 8% of caffeine AUC variation could be explained by a CYP1A1/1A2 promotor polymorphism (rs2470893). In contrast, nearly all of the variations (99%) of NAT2 activity were explained by genetic effects. This study illustrates two very different situations in pharmacogenetics from an almost exclusively genetic determination of NAT2 activity with no environmental modulation to only moderate genetic effects on CYP1A2 activity with strong environmental modulation.

Determination of NAT2 acetylation status in the Greenlandic population.

N-acetyltransferase 2 (NAT2) is a well-studied phase II xenobiotic metabolizing enzyme relevant in drug metabolism and cancerogenesis. NAT2 activity is largely determined by genetic polymorphisms in the coding region of the corresponding gene. We investigated NAT2 acetylation status in 1556 individuals from Greenland based on four different single nucleotide polymorphism (SNP) panels and the tagging SNP rs1495741. There was good concordance between the NAT2 status inferred by the different SNP combinations. Overall, the fraction of slow acetylators was low with 17.5 % and varied depending on the degree of Inuit ancestry; in individuals with <50 % Inuit ancestry, we observed more than 25 % slow acetylators reflecting European ancestry. Greenland has a high incidence of tuberculosis, and individual dosing of isoniazid according to NAT2 status has been shown to improve treatment and reduce side effects. Our findings could be a first step in pharmacogenetics-based tuberculosis therapy in Greenland.

Association between N-acetyltransferase 2 polymorphisms and pancreatic cancer risk: a meta-analysis.

N-acetyltransferase 2 (NAT2) is an essential phase II enzyme in the metabolism of aromatic and heterocyclic amines and of hydrazines. NAT2 activity can be divided into three phenotypes: rapid, intermediate, and slow. Studies identifying an association between NAT2 polymorphism and the risk of pancreatic cancer have shown conflicting results. In order to assess this relationship comprehensively, we performed a meta-analysis that involved 1607 patients with pancreatic cancer and 1682 controls from six studies, which were selected from a group of ten, identified by a search of PubMed and Embase databases up to July 2014. Relative risks (RRs) with 95% confidence intervals (CIs) were used to evaluate the relationships. In the overall analysis, no significant associations between NAT2 rapid acetylation genotypes and pancreatic cancer risk (RR = 0.93, 95%CI = 0.73-1.19) were found; however, the results showed significant heterogeneity (I2 = 55.0%). The results from subgroup analysis suggested that the rapid genotypes might decrease the risk of pancreatic cancer (RR = 0.56, 95%CI = 0.38-0.84) in Turkey, although the association was not significant in the United States population (RR = 0.97, 95%CI = 0.71-1.34) or in the multi-center studies (RR = 1.10, 95%CI = 0.90-1.34). Analysis of the slow acetylation genotypes demonstrated the converse outcomes. In conclusion, the results of our study suggested that the NAT2 slow acetylation genotypes might increase the susceptibility to pancreatic cancer in Europe but that these have no significant effects in the United States and multi-center populations.

The NAT2 tag SNP rs1495741 correlates with the susceptibility of antituberculosis drug-induced hepatotoxicity

Earlier studies have demonstrated an association between N-acetyltransferase 2 (NAT2) catalytic activity and the genotype of a recently published tag single nucleotide polymorphism (SNP), rs1495741. There have been no reports on the relationship between the rs1495741 genotype and antituberculosis drug-induced hepatotoxicity (ATDIH) to date. The aim of the present study was to determine the frequency of the NAT2 tag SNP (rs1495741) in the Taiwanese and its relation to the incidence of ATDIH. A total of 348 tuberculosis patients were enrolled to determine the frequency of NAT2 tag SNP rs1495741 and its relation to the incidence of ATDIH. The conventional NAT2 variants alleles have also been investigated. Furthermore, to evaluate the correlation of NAT2 activity and rs1495741 genotypes, a pharmacokinetic study of isoniazid was also conducted in healthy volunteers. Among the 348 tuberculosis patients, 20 (5.7%) were diagnosed with ATDIH. The frequencies of the three rs1495741 genotypes, viz., AA, AG, and GG, were 24.7, 52.3, and 23.0%, respectively. Signi&filig;cant differences among rs1495741 genotypes and susceptibility to hepatotoxicity were noted (odds ratio=14.068, P<0.05). Moreover, the rs1495741 genotypes showed an association with the isoniazid dosage required for induction of hepatotoxicity. In the pharmacokinetic study, NAT2 activity was strongly associated with genotype categories (P<0.001). The present study demonstrated that the three genotypes according to rs1495741 were in good accordance with conventional NAT2 alleles-inferred phenotypes and the tag SNP could be used as a proxy to determine the susceptibility to ATDIH.

Comparison ofN-Acetyltransferase-2 Enzyme Genotype-Phenotype and Xanthine Oxidase Enzyme Activity Between Swedes and Koreans

The aim of this study was to compare xanthine oxidase (XO) and N-acetyltransferase-2 (NAT2) genotype and phenotype between Swedes (n = 113) and Koreans (n = 150), as well as to investigate the effect of sex, smoking, age, and oral contraceptive (OC) use on enzyme activities, using caffeine as a probe. XO and NAT2 activities were estimated by 1U/(1U+1X) and AFMU/(AFMU+1X+1U) urinary ratios, respectively. Participants were genotyped for 191G>A, 341T>C, 590G>A, and 857G>A NAT2 polymorphisms. There was no significant difference in XO activity between Swedes and Koreans. In Swedes, higher XO activity was observed in women (P < .003). There were significant differences in NAT2 genotype and phenotype between Swedes and Koreans. Koreans display significantly higher frequency of NAT2 fast acetylator genotype (89%), whereas the slow acetylator genotype is predominant (62%) in Swedes (P < .0001). Significantly higher NAT2 activity was observed in Koreans compared to Swedes (P < .0001). Having the same NAT2 fast acetylator genotype, Koreans display higher enzyme activity than Swedes (P < .004). OC use significantly increased NAT2 activity in Swedish women. In conclusion, Koreans display higher NAT2 activity than Swedes regardless of NAT2 genotype. Ethnicity, OC use, and genotype determine NAT2 activity, whereas sex is the only determinant of XO activity.

Heterocyclic amine intake, smoking, cytochrome P450 1A2 and N-acetylation phenotypes, and risk of colorectal adenoma in a multiethnic population

ObjectiveHeterocyclic amines (HAA) are animal carcinogens that are present in meat cooked at high temperature and in tobacco smoke. These compounds require activation by cytochrome P450 1A2 (CYP1A2) and N-acetyltransferase-2...

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.

Altered xanthine oxidase and N‐acetyltransferase activity in obese children

It is well established that oxidative and conjugative enzyme activity differs between obese and healthy-weight adults. However, the effect of obesity on drug metabolism in children has not been studied extensively. This study examined whether obese and healthy-weight children vary with respect to oxidative enzyme activity of CYP1A2, xanthine oxidase (XO) and conjugative enzyme activity of N-acetyltransferase 2 (NAT2). In vivo CYP1A2, XO and NAT2 activity was assessed in obese (n= 9) and lean (n= 16) children between the ages of 6-10 years using caffeine (118.3 ml Coca Cola®) as probe. Urine samples were collected in 2-h increments over 8 h. Caffeine and metabolites were measured using LC/MS, and urinary metabolic ratios were determined based on reported methods. Sixteen healthy-weight and nine obese children were evaluated. XO activity was elevated in paediatric obese volunteers compared with non-obese paediatric volunteers (XO metabolic ratio of 0.7 ± 0.06 vs. 0.6 ± 0.06, respectively, 95% CI 0.046, 0.154, P < 0.001). NAT2 activity was fivefold higher in the obese (1 ± 0.4) as compared with non-obese children (0.2 ± 0.1), 95% CI 0.26, 1.34, P < 0.05. However, no difference was observed in CYP1A2 activity between the groups (95% CI -2.72, 0.12, P > 0.05). This study provides evidence that obese children have elevated XO and NAT2 enzyme activity when compared with healthy-weight controls. Further studies are needed to determine how this may impact the efficacy of therapeutic agents that may undergo metabolism by these enzymes.