Cytochrome P450 2E1 Genotype Research Articles

Pharmacogenetic variability of tuberculosis biomarkers in native and mestizo Peruvian populations.

In Peru, 29 292 people were diagnosed with tuberculosis in 2022. Although tuberculosis treatments are effective, 3.4%-13% are associated with significant adverse drug reactions, with drug-induced liver injury (DILI) considered the most predominant. Among the first-line antituberculosis drugs, isoniazid is the main drug responsible for the appearance of DILI. In liver, isoniazid (INH) is metabolized by N-acetyltransferase-2 (NAT2) and cytochrome P450 2E1 (CYP2E1). Limited information exists on genetic risk factors associated with the presence of DILI to antituberculosis drugs in Latin America, and even less is known about these factors in the native and mestizo Peruvian population. The aim of this study was to determine the prevalence of NAT2 and CYP2E1 genotypes in native and mestizo population. An analytical cross-sectional analysis was performed using genetic data from mestizo population in Lima and native participants from south of Peru. NAT2 metabolizer was determined as fast, intermediate and slow, and CYP2E1 genotypes were classified as c1/c1, c1/c2 and c2/c2, from molecular tests and bioinformatic analyses. Of the 472 participants, 36 and 6 NAT2 haplotypes were identified in the mestizo and native population, respectively. In mestizo population, the most frequent NAT2*5B and NAT2*7B haplotypes were associated with DILI risk; while in natives, NAT2*5G and NAT2*13A haplotypes were associated with decreased risk of DILI. For CYP2E1, c1/c1 and c1/c2 genotypes are the most frequent in natives and mestizos, respectively. The linkage disequilibrium of NAT2 single nucleotide polymorphisms (SNPs) was estimated, detecting a block between all SNPs natives. In addition, a block between rs1801280 and rs1799929 for NAT2 was detected in mestizos. Despite the limitations of a secondary study, it was possible to report associations between NAT2 and CYP2E alleles with Peruvian native and mestizo by prevalence ratios. The results of this study will help the development of new therapeutic strategies for a Tuberculosis efficient control between populations.

Association of Cytochrome P450 2E1 and N-Acetyltransferase 2 Genotypes with Serum Isoniazid Level and Anti-Tuberculosis Drug-Induced Hepatotoxicity: A Cross-Sectional Study.

Anti-tuberculosis drug-induced hepatotoxicity can result from genetic polymorphism of the isoniazid (INH) metabolizing enzyme. This study aimed to determine the effect of genetic polymorphism of N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1) genes on serum isoniazid level and drug-induced hepatotoxicity. A cross-sectional study was conducted on 120 patients (with and without hepatotoxicity) with pulmonary tuberculosis from June 2019 to April 2022 in Tehran (Iran). High-performance liquid chromatography was used to measure the serum concentration of INH and acetylisoniazid (AcINH). NAT2 and CYP2E1 genotypes were determined using polymerase chain reaction and restriction fragment length polymorphism methods. Data were analyzed using SPSS software (version 22.0) with independent two-sample t test, Chi square test, or Fisher's exact test. P<0.05 was considered statistically significant. A total of 40 patients showed hepatotoxicity. The risk of anti-tuberculosis drug-induced hepatotoxicity was significantly higher in patients who are slow acetylator (SA) phenotype than in rapid or intermediate acetylator (P<0.001). NAT2*4/*4 genotypes were not found in patients with hepatotoxicity. The frequency of NAT2*5 and NAT2*6 haplotypes and serum INH concentration was significantly higher in patients with hepatotoxicity than in those without (P=0.003, P<0.001, and P<0.001, respectively). NAT2*4 haplotype was correlated with protection against hepatotoxicity. A combination of SA and CYP2E1 C1/C1 genotype was significantly associated with hepatotoxicity (P<0.001). Hepatotoxicity in Iranian patients with tuberculosis was confirmed due to the presence of NAT2 SA polymorphism. Determining NAT2 and CYP2E1 genotypes and/or INH concentration can be a valuable tool to identify patients susceptible to hepatotoxicity.

NAT2 and CYP2E1 polymorphisms and antituberculosis drug-induced hepatotoxicity in Peruvian patients.

BackgroundIn Peru, 32,970 people were diagnosed with tuberculosis (TB) in 2019. Although TB treatment is effective, 3.4%–13% is associated with significant adverse drug reactions (ADR), considering drug‐induced liver injury (DILI) as the most prevalent. Among the first‐line anti‐TB drugs, isoniazid (INH) is primarily responsible for the occurrence of DILI. INH is metabolized in the liver by the enzymes N‐acetyltransferase‐2 (NAT2) and Cytochrome P450 2E1 (CYP2E1). Based on the previous studies, we hypothesized that the interactions between slow CYP2E1 genotype and NAT2 slow acetylators will induce DILI in TB patients.MethodsIn this cross‐sectional study, all 377 participants completed their anti‐TB treatment, and we genotyped SNPs: rs1041983, rs1801280, rs1799929, rs1799930, rs1208, and rs1799931 for NAT2 and rs3813867 and rs2031920 for CYP2E1.ResultsWe found that rapid, intermediate, and slow NAT2 acetylator were 15%, 38%, and 47%, respectively, in the general population. Intermediate NAT2 acetylator is the least prevalent among patients with adverse reactions (p = 0.024). We did not confirm our hypothesis, however, we found that the combination of intermediate NAT2 acetylators and CYP2E1 c1/c1 genotype significantly protected (OR = 0.16; p = 0.049) against the development of DILI in our population.ConclusionWe propose that the presence of NAT2 intermediate and CYP2E1 c1/c1 genotype could help in therapeutic drug monitoring, and optimize its therapeutic benefits while minimizing its risk for side effects or toxicity.

Genetic variants of ALDH2-rs671 and CYP2E1-rs2031920 contributed to risk of hepatocellular carcinoma susceptibility in a Chinese population.

ObjectiveAcetaldehyde dehydrogenase 2 (ALDH2) and cytochrome P450 2E1 (CYP2E1) have been associated with hepatocellular carcinoma (HCC) susceptibility and prognosis. The polymorphisms ALDH2 rs671 and CYP2E1 rs2031920 are reportedly correlated with the prevalence of HCC in other countries. The aim of this study was to investigate associations between ALDH2 and CYP2E1, and HCC susceptibility in a population of Guangxi, southern China, an area with a high incidence of HCC.Patients and methodsThe study cohort included 300 HCC cases, 292 healthy controls for HCC susceptibility analysis, and another 20 HCC cases and 10 healthy controls for ascertainment. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method.ResultsThe study results demonstrated that mutant genotypes of ALDH2 (G/A and A/A) led to significant differences in HCC susceptibility, as compared with the wild genotype (G/G) with the same C1/C1 genotype in non-drinking individuals (adjusted P=0.010, OR=0.20, 95% CI=0.06–0.68). The mutant genotypes of CYP2E1 (C1/C2 and C2/C2) brought about significant differences in HCC susceptibility, as compared with the wild genotype (C1/C1) and the same G/G genotype (adjusted P=0.025, OR=0.42, 95% CI=0.20–0.90). Drinking plays a role in HCC susceptibility in the same G/G genotype individuals (adjusted P=0.004, OR=0.32, 95% CI=0.15–0.69), but had no impact when combined with CYP2E1 for analysis (all P>0.05).ConclusionThese results suggest that the mutant genotypes of ALDH2 and CYP2E1 may be protective factors for HCC susceptibility in Guangxi province, China.

Association between effectiveness of tuberculosis treatment and cytochrome P-4502E1 polymorphism of the patients.

The risk of antituberculosis (TB) drug-induced liver injury could be determined by patients' genotype polymorphism of the xenobiotic-metabolizing enzymes. To find the meaning of cytochrome P-4502E1 (CYP2E1) polymorphism in TB patients. Corresponding of CYP2E1 polymorphism in TB patients with the level of isoniazid and rifampicin as well as for the outcome and toxicity development during inpatient TB treatment. CYP2E1 genotype was detected with the help of polymerase chain reaction and endonuclease analysis. The level of rifampicin, isoniazid, diene conjugates (DC), and catalase activity in the blood was determined spectrophotometrically. We have considered medical records at the beginning and at the end of inpatient treatment. Kruskal-Wallis, ANOVA, and Chi-square tests were used in this study. The concentration of rifampicin 6 h after its intake was 17.6% higher in carriers of slow metabolizer (SM) CYP2E1 genotype than in patients with rapid metabolizer (RM) genotype that proved a participation of hepatic enzyme CYP2E1 in metabolism of rifampicin. According to obtained results in TB patients with RM genotype, the indexes of cytolysis (alanine aminotransferase, aspartate aminotransferase) and bile stasis (gamma-glutathione transferase) were higher comparatively to SM genotype both before and after inpatient treatment. This correlated with a higher concentration of DC in the blood (+8.6%) and lower plasma catalase activity (-50.0%) in the patients with RM genotype comparatively with the patients with SM genotypes. Polymorphism of CYP2E1 genotype is an important criterion for the development of hepatotoxicity before and during TB treatment while increased rifampicin level has no influence on it.

Association between CYP2E1 polymorphisms and risk of differentiated thyroid carcinoma.

Differentiated thyroid carcinoma (DTC) results from complex interactions between genetic and environmental factors. Known etiological factors include exposure to ionizing radiations, previous thyroid diseases, and hormone factors. It has been speculated that dietary acrylamide (AA) formed in diverse foods following the Maillard's reaction could be a contributing factor for DTC in humans. Upon absorption, AA is biotransformed mainly by cytochrome P450 2E1 (CYP2E1) to glycidamide (GA). Considering that polymorphisms within CYP2E1 were found associated with endogenous levels of AA-Valine and GA-Valine hemoglobin adducts in humans, we raised the hypothesis that specific CYP2E1 genotypes could be associated with the risk of DTC. Analysis of four haplotype tagging SNPs (ht-SNPs) within the locus in a discovery case-control study (N=350/350) indicated an association between rs2480258 and DTC risk. This ht-SNP resides within a linkage disequilibrium block spanning intron VIII and the 3'-untranslated region. Extended analysis in a large replication set (2429 controls and 767 cases) confirmed the association, with odds ratios for GA and AA genotypes of 1.24 (95% confidence interval (CI) 1.03-1.48) and 1.56 (95% CI, 1.06-2.30), respectively. Functionally, the minor allele was associated with low levels of CYP2E1 mRNA and protein expression as well as lower enzymatic activity in a series of 149 human liver samples. Our data support the hypothesis that inter-individual differences in CYP2E1 activity could modulate the risk of developing DTC suggesting that the exposure to specific xenobiotics, such as AA, could play a role in this process.

Analysis of ADH1B Arg47His, ALDH2 Glu487Lys, and CYP4502E1 polymorphisms in gastric cancer risk and interaction with environmental factors.

Gastric cancer is the fourth commonly diagnosed cancer and the second most frequent cause of cancer death worldwide. Genetic variations in ADH1B and ALDH2 may alter the function and activity of the corresponding enzymes, leading to differences in acetaldehyde exposure between drinkers. Cytochrome P4502E1 (CYP4502E1) is a phase I enzyme that plays an important role in metabolizing nitrosamine compounds and the bioactivation of procarcinogens. During the period of July 2013 to July 2015, 246 patients and 274 controls were enrolled from the First Affiliated Hospital of Jinan University. In the codominant model, the AA genotype of ALDH2 Glu487Lys significantly elevated the risk of gastric cancer in comparison with the GG genotype of ALDH2 Glu487Lys. In the recessive model, the AA genotype of ALDH2 Glu487Lys significantly increased the risk of gastric cancer compared to the GG+GA genotype (OR = 2.34 95%CI = 1.02-5.70). We found in the codominant model that individuals harboring the C2/C2 genotype of CYP4502E1 had a higher risk of developing gastric cancer than those with the C1/C1 genotype. In addition, in the recessive model, we found that the C2/C2 genotype correlated with an elevated risk of gastric cancer in comparison with the C1/C1+C1/C2 genotype (OR = 4.90, 95%CI = 2.04-13.51). However, no significant relationship was measured between ADH1B Arg47His and gastric cancer risk. In summary, the results of our study indicate that ALDH2 Glu487Lys and CYP4502E1 polymorphisms could be risk factors for the development of gastric cancer in the Chinese population.

Functional RsaI/PstI polymorphism in cytochrome P450 2E1 contributes to bladder cancer susceptibility: evidence from a meta-analysis.

Cytochrome P450 2E1 (CYP2E1) might be involved in the development of bladder cancer. However, previous studies of any association between CYP2E1 RsaI/PstI polymorphism and bladder cancer risk have yielded conflicting results. In this study, we performed a more precise estimation of the relationship by a meta-analysis based on the currently available evidence from the literature. To assess the effect of CYP2E1 RsaI/PstI polymorphism on bladder cancer susceptibility, a meta-analysis of 6 available studies with 1,510 cases and 1,560 controls were performed through Feb 2014. Summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were used to estimate the strength of association for CYP2E1 RsaI/PstI polymorphism under different genetic models. When available studies were pooled into the meta-analysis, we found that the C1C2 and C2C2 genotypes of CYP2E1 RsaI/PstI polymorphism significantly decreased bladder cancer risk under different genetic models (heterozygote: OR=0.766, 95%CI=0.613-0.957, POR=0.019; homozygote: OR=0.51, 95%CI=0.303- 0.858, POR=0.011; dominant: OR=0.733, 95%CI=0.593-0.905, POR=0.004; recessive: OR=0.565, 95%CI=0.337-0.947, POR=0.030). Subgroup analysis indicated that C2C2 genotype was significantly associated with decreased bladder cancer risk under the homozygote genetic model in Caucasians. There was no evidence of heterogeneity or publication bias. The current meta-analysis suggested that the CYP2E1 RsaI/ PstI polymorphism might be associated with bladder cancer susceptibility, especially in Caucasians. Further studies are needed to validate the above conclusion.

Genetic variations of superoxide dismutase 2 and cytochrome P450 2E1 in non‐alcoholic steatohepatitis

Non-alcoholic fatty liver disease is the most prevalent liver disease in the world. However, the exact mechanisms that lead to development of advanced non-alcoholic steatohepatitis (NASH) are unknown. Oxidative stress may be an important pathogenic factor in NASH. Manganese superoxide dismutase (SOD2) is an important antioxidant phase 2 enzyme that can reduce reactive oxidative substances and protect hepatocytes. In contrast, cytochrome P450 2E1 (CYP2E1) has pro-oxidant activity and may enhance oxidative stress and counteract the effect of SOD2. Little is known regarding the associations of genetic variants of these enzymes with the risk of NASH. We aimed to investigate the association of genetic variants of SOD2 and CYP2E1 with susceptibility to NASH. Data from 100 patients with NASH, 31 patients with non-alcoholic steatosis (NAS) and 90 healthy controls were analysed. Their DNA was retrieved for genotyping SOD2 47T>C and CYP2E1 -1053C>T variation by polymerase chain reaction. There was no statistical difference in the frequency distributions of SOD2 and CYP2E1 genotypes among the NASH, NAS and control groups. However, the frequency of the SOD2 C variant was significantly higher in the NASH group than in the NAS and control groups (22% vs. 14.5% and 11.1%, respectively; P=0.015). After adjustment for confounders, the SOD2 C/C and C/T genotypes remained associated with the risk of NASH (odds ratio, 2.81; 95% confidence interval, 1.37-5.76; P= 0.005). The anti-oxidative SOD2 47T>C genetic variant might increase susceptibility to NASH in Chinese. Individuals with the SOD2 C variant may have a higher risk for NASH.

The role of cigarette smoking and liver enzymes polymorphisms in anti-tuberculosis drug-induced hepatotoxicity in Brazilian patients

Tuberculosis (TB) is still a major health concern and side-effects related to the treatment, especially drug-induced hepatotoxicity (DIH), should be better investigated. In the present study, a possible association between anti-TB DIH and cigarette smoking, N-acetyltransferase 2 (NAT2), Cytochrome P450 2E1 (CYP2E1) and Cytochrome P450 3A4 (CYP3A4) genotypes was studied in 131 TB Brazilian patients. The NAT2 and CYP3A4 genetic polymorphisms were determined using a polymerase chain reaction (PCR) direct sequencing approach and genetic polymorphisms of CYP2E1 gene were determined by restriction fragment length polymorphism (RFLP). The risk of anti-TB DIH was lower in rapid/intermediate acetylators when compared to slow acetylators (OR: 0.34, CI 95: 0.16-0.71; p<0.01). A decreased risk of developing anti-TB DIH was also observed in active smokers when compared to non-smokers (OR: 0.28, 95 CI: 0.11-0.64; p<0.01). Significant association between CYP3A4 genotypes and hepatotoxicity was not observed, as well as between CYP2E1 genotype and hepatotoxicity, whose frequency of patients with wild homozygous was more prevalent. The anti-TB drugs interactions with smoking on hepatotoxicity, as well as the NAT2 phenotype, may require to adjust therapeutic regimen dosages or alarm in case of adverse event developments.

Association of N‐acetyltransferase 2 and cytochrome P450 2E1 gene polymorphisms with antituberculosis drug‐induced hepatotoxicity in Western India

Tuberculosis (TB) is a major public health problem in India. Despite the treatment availability and monitoring, drug-induced hepatotoxicity (DIH) is a serious concern and can lead to discontinuation of treatment. Anti-TB DIH is well known and can aggravate because of pharmacokinetic and pharmacodynamic interactions. Genetic polymorphism in the drug-metabolizing enzyme genes is an important factor that predisposes certain fraction of the population to drug-induced toxicity. The purpose of this study was to assess the association of N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1) gene polymorphism with anti-TB DIH in Western Indian population. A prospective cohort study of 215 patients taking treatment against TB was performed. The NAT2 and CYP2E1 genotypes were determined using polymerase chain reaction and restriction fragment length polymorphism methods. Logistic regression model was used to calculate odds ratio at 95% confidence interval and their respective P values. The risk of anti-TB DIH was significantly higher in slow acetylator (SA) than in intermediate and rapid acetylator of NAT2 genotypes (odds ratio: 2.3, P = 0.01). We also observed the homozygous point mutation at position 481, associated with higher risk of hepatotoxicity (P < 0.01). The major haplotype NAT2*4 seems to provide protection in DIH compared with non-DIH TB patients (P = 0.04). However, we did not find a significant association between CYP2E1 genotypes and anti-TB DIH. Increased susceptibility to isoniazid (INH)-induced hepatotoxicity due to presence of NAT2 SA polymorphism was demonstrated in Western Indian population. NAT2 genotyping can therefore serve as an important tool for identifying patients predisposed to anti-TB DIH.

&lt;I&gt;N&lt;/I&gt;-acetyl transferase 2 and cytochrome P450 2E1 genes and isoniazid-induced hepatotoxicity in Brazilian patients

Isoniazid (INH) is related to the development of hepatotoxicity in some patients. To investigate the role of N-acetyl transferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1) in the hepatotoxicity of patients treated with INH in an Amazonian Brazilian population. Patients undergoing anti-tuberculosis treatment were investigated. Hepatotoxicity was defined as an increase of more than three times the upper limit of normal in serum alanine aminotransferase levels after treatment. NAT2 genotypes were identified by sequencing, whereas CYP2E1 alleles were detected using polymerase chain reaction based methods. Of the 270 individuals included in the study, 18 (6.7%) developed drug-related hepatotoxicity. A high association was found between slow acetylators and hepatotoxicity, particularly with regard to allele *5. The adjusted risk of developing hepatotoxicity was significant in individuals carrying two slow acetylation alleles (P = 0.036, OR 3.05, 95%CI 1.07-8.64). In all of the CYP2E1 markers examined, wild homozygous genotypes were more prevalent in subjects with hepatotoxicity than in controls; however, the difference was not statistically significant. Joint evaluation of the genes revealed a high risk of developing hepatotoxicity in slow acetylators with CYP2E1 wild alleles (adjusted OR 4.26; 95%CI 1.47-12.37, P = 0.008). Large-scale screening for NAT2 and CYP2E1 genotypes can prove useful in predicting the risk of adverse effects.

Contribution of CYP2E1 polymorphism to aging in the mechanical workshop workers

Aging is attributed to both genetic and environmental factors. Occupational exposure is one of the environmental factors with potential genotoxic effects. Researchers try to determine factors involved in genetic damages at hazards exposure that could accelerate aging. Cytochrome P450 2E1 (CYP2E1) gene contributes in activation and detoxification of the environmental hazards. This polymorphism plays an important role in susceptibility of inter-individuals to DNA damage at the occupational exposure. The current study evaluated the possible influence of this gene polymorphism in aging by genomic damages through the biomarkers alterations of micronuclei (MN), comet tail length and telomere length shortening at the exposure. In this study, buccal cells were collected from the oral cavity of exposed workers and non-exposed controls. The CYP2E1 genotypes were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The wild genotype significantly affected MN frequency (p = 0.007) and relative telomere length (p = 0.047) in the older group of workers. It was concluded that the interaction of gene polymorphism and exposure enhances DNA damage and accelerates aging consequently.

The modifying effect of CYP2E1, GST, and mEH genotypes on the formation of hemoglobin adducts of acrylamide and glycidamide in workers exposed to acrylamide

This study assesses the association of acrylamide (AA) and glycidamide (GA) hemoglobin adducts (AAVal and GAVal) and their ratios with genetic polymorphisms of the metabolic enzymes cytochrome P450 2E1 (CYP2E1), exon 3 and 4 of microsomal epoxide hydrolase (mEH3 and mEH4), glutathione transferase theta (GSTT1), and mu (GSTM1) or/and the combinations of these polymorphisms, involved in the activation and detoxification of AA in humans. Fifty-one AA-exposed workers and 34 controls were recruited and provided a post-shift blood sample. AAVal and GAVal were determined simultaneously using isotope-dilution liquid chromatography-electronspray ionization/tandem mass spectrometry (LC-ESI–MS/MS). Genetic polymorphisms of CYP2E1, mEH3 and 4, GSTT1, and GSTM1 were also analyzed. Our results reveal that the GAVal/AAVal ratio, potentially reflecting the proportion of AA metabolized to GA, ranged from 0.13 to 0.45 with a mean at 0.27. Multivariate regression analysis demonstrates that the joint effect of CYP2E1, GSTM1, and mEH4 genotypes was significantly associated with AAVal and GAVal levels after adjustment for AA exposures. These results suggest that mEH4 and the combined genotypes of CYP2E1, GSTM1 and mEH4 may be associated with the formation of AAVal and GAVal. Further studies may be needed to shed light on the roles that phase I and II enzymes play in AA metabolism.

NAT2 and CYP2E1 polymorphisms associated with antituberculosis drug‐induced hepatotoxicity in Chinese patients

1. The present study investigated the relationship between antituberculosis (anti-TB) drug-induced hepatotoxicity and genetic polymorphisms of two important drug-metabolizing enzymes involved in the metabolism of isoniazid, namely N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1). 2. A polymerase chain reaction direct sequencing approach was used to detect genetic polymorphisms of the NAT2 and CYP2E1 genes in tuberculosis (TB) patients with (n = 101) or without (n = 107) anti-TB drug-induced hepatotoxicity. Associations between various genetic polymorphisms and anti-TB drug-induced hepatotoxicity were then determined. 3. Patients with NAT2 (282TT , 590AA and 857GA) alleles had an increased susceptibility to anti-TB drug-induced hepatotoxicity. The slow acetylator NAT2 genotypes (especially NAT2*6A/7B and NAT2*6A/6A) were risk factors for hepatotoxicity (odds ratio (OR) 9.57 (P < 0.001) for NAT2*6A/7B; OR 5.24 (P = 0.02) for NAT2*6A/6A). 4. The CYP2E1 genotype per se was not significantly associated with the development of anti-TB drug-induced hepatotoxicity. However, the combination of the CYP2E1 C1/C1 genotype with a slow acetylator NAT2 genotype increased the risk of anti-TB drug-induced hepatotoxicity (OR 5.33; P = 0.003) compared with the combination of a rapid acetylator NAT2 genotype with either a C1/C2 or C2/C2 genotype. 5. Thus, slow acetylators with the NAT2*6A/7B and NAT2*6A/6A genotypes combined with the C1/C1 CYP2E1 genotype may be involved in the pathogenesis of anti-TB drug-induced hepatotoxicity. 6. The present findings may be explained, in part, by changes in the metabolism of the anti-TB drug isoniazid induced via NAT2 and CYP2E1, a metabolic process known to produce hepatotoxic intermediates.

Role of CYP2E1 genotypes in susceptibility to colorectal cancer in the Kashmiri population

Cytochrome P450 2E1 (CYP2E1) is a key enzyme involved in the metabolic activation of procarcinogens such as N-nitrosoamines and low-molecular-weight organic compounds. The main aim of this study was to determine whether CYP450 2E1 polymorphisms are associated with the risk of colorectal cancer (CRC). We investigated the genotype distribution of the CYP2E1 gene RsaI and a 96-base pair (bp) insertion in 86 CRC cases in comparison with 160 healthy subjects. We found the frequency of the CYP2E1 RsaI genotype to be 53.5 per cent (46/86) for c1/c1, 17.4 per cent (15/86) for c1/c2 and 29.1 per cent (25/86) for c2/c2, and the CYP2E1 98-bp insertion frequencies to be 63.9 per cent (55/86) for non-insertion (i/i), 22.1 per cent (19/86) for heterozygous insertion (i/I) and 36.0 per cent (12/86) for homozygous insertion (I/I) among CRC cases. We also found the CYP2E1 RsaI c2/c2 and CYP2E1 98-bp heterozygous i/I genotypes to be significantly associated with an increased risk of CRC (p = 0.01). We suggest that CYP2E1 polymorphisms are involved in the susceptibility to developing CRC in the ethnic Kashmiri population.

Cytochrome P450 2E1 RsaI/PstI and DraI polymorphisms are risk factors for lung cancer in Mongolian and Han population in inner Mongolia

To explore the relationship between cytochrome P450 2E1 (CYP2E1) RsaI/PstI and DraI polymorphism and lung cancer susceptibility in Mongolian and Han population in Inner Mongolia of China. CYP2E1 RsaI/PstI and DraI polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism in 64 lung cancer patients, 150 healthy Mongolian and 150 healthy Han individuals. The distribution of genotype and allele frequencies of CYP2E1 RsaI/PstI and DraI polymorphisms were studied. The risk of lung cancer was increased in individuals with CYP2E1 (cl/cl) and CYP2E1 (DD) with OR values of 2.431 (95%CI=1.082-5.460) and 2.778 (95%CI=1.358-5.683) respectively (P<0.05). When CYP2E1 RsaI/PstI and DraI polymorphisms were combined, the risk of lung cancer was reduced in individuals with CYP2E1 (cl/c2+c2/c2 and DD+CC) with OR values of 0.233 (95%CI=0.088-0.615, P<0.05). In smokers, the susceptibility to lung cancer was higher in the individuals with CYP2E1 (c1/c1) and CYP2E1 (DD) than in the individuals with c2 and C allele (P<0.05, OR=2.643 and 4.308 respectively). There was no significant difference in distribution of CYP2E1 genotype frequency between healthy Mongolian, Han population and lung cancer patients, healthy controls in Inner Mongolia. CYP2E1 (c1/c1) and CYP2E1 (DD) are predisposing factors of lung cancer in population in Inner Mongolia. CYP2E1 (c2﹢C) co-mutation may decrease the risk of lung cancer. Smoking exerts synergetic effect with CYP2E1 (c1/c1) and CYP2E1 (DD) on the occurrence of lung cancer.

Effect of Different Doses of Wheatgrass in Prevention of Carbon Tetrachloride Induced Hepatotoxicity in Rats

© 2011, INASL 39 HEPATOTOXICITY Effect of Different Doses of Wheatgrass in Prevention of Carbon Tetrachloride Induced Hepatotoxicity in Rats JK Kamboj*, SV Rana*, DK Dhawan**, K Vahiphei*** Departments of *Gastroenterology and **Pathology, PGIMER, Chandigarh, ***Department of Biophysics, Punjab University, Chandigarh Introduction: Wheatgrass (Triticum aestivum), rich in chlorophyll and various antioxidants, is promoted to treat a number of conditions including common cold, cough, fever, eczema and burns, etc. Aim: To determine the protective effect of different doses of wheatgrass in hepatic tissue of Wistar rats damaged by CCl4. Material and Methods: Wheatgrass was administered orally at different doses of 20 mg, 40 mg, 60 mg and 80 mg/100 g by body weight in drinking water for 4 weeks along with CCl4 injection given subcutaneously at a dose of 2 mL/Kg body weight twice a week. Wheatgrass dose was started 2 weeks prior to first injection of CCl4. Carbon tetrachloride was also administered in control group for 4 weeks and one group was given only wheatgrass at a maximum dose of 80 mg/100 g by body weight/day to check any adverse effect of wheatgrass on liver. The effect to different treatments was studied on serum enzymes like alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in rats at different time intervals of 2 and 4 weeks and the rat liver was analyzed histologically at the end of study. Results: Serum ALP, AST, ALT activity was significantly increased when estimated at the intervals of 2 and 4 weeks as compared to baseline values in CCl4 group. Interestingly, supplementation of wheatgrass to rats helped in regulating the altered activities of ALP, AST and ALT in serum at 4 weeks. However, wheatgrass treatment to rats did not indicate any significant change in the activities of all abovementioned liver enzymes at the interval of 2 weeks. Histologically, there was necrosis, portal triaditis and lobular inflammation in CCl4 group. Maximum protection was observed biochemically and histologically with wheatgrass dose of 80 mg/100 g body weight Conclusion: Carbon tetrachloride caused liver toxicity and wheatgrass treatment prevented the increase in liver enzymes and histology depending on the dose of wheatgrass. Conflict of Interest: None Relation of NAT2, CYP2E1 and GST Gene Polymorphisms with Anti-tuberculosis Treatment Induced Hepatotoxicity in North Indian Patients SV Rana*, SK Sharma**, RP Ola*, SK Arora***, SK Sinha*, JK Kamboj*, K Singh* Department of Superspecialty of *Gastroenterology, **Biophysics and ***Immunopathology, PGIMER, Chandigarh Background: Antituberculosis treatment (ATT) induced hepatitis is attributed to isoniazid (INH). Isoniazid is metabolized by hepatic N-acetyltransferase-2 (NAT-2) and cytochrome P-450 2E1 (CYP2E1) to form hepatotoxins. Glutathione-S-transferase (GST) plays an important role in prevention of ATT-induced hepatotoxicity. Deficiency of GST activity because of homozygous null mutations at GSTM1 and GSTT1 loci may modulate susceptibility to ATT-induced hepatotoxicity. Aim: To evaluate whether polymorphisms of NAT-2, GST and CYP2E1 gene were associated with ATT-induced hepatotoxicity in North Indian patients. Methods: In this prospective study, 250 patients treated with ATT for tuberculosis were genotyped for polymorphisms of NAT-2, GST and CYP2E1. NAT-2, CYP2E1 and GST genotypes were determined by PCR and multiplex PCR with restriction fragment length polymorphism analysis (RFLP). Results: Two hundred fifty tuberculosis (TB) patients on ATT (153 males) were studied. Out of 250 patients, 32 (12.8%) developed hepatotoxicity. NAT-2 gene allele 4/4 was present in 18/32 (56.2%) of hepatotoxicity patients while in 76/218 (34.8%) in non-hepatotoxicity patients. Allele 4/6, 5/5, 6/6 and 7/7 were not present in hepatotoxicity patients while these were present in non-hepatotoxicity patients. In GST, out of 32 hepatotoxicity patients, 5 (15.6%) showed GSTM1, 9 out of 32 (28.0%) GSTT1 and 18 out of 32 (56.3%) GSTT1/ GSTM1/s-globulin. While 69 out of 218 (31.7%) showed GSTM1, 34 (15.6%) GSTT1, and 115 (52.7%) GSTT1/GSTM1/s-globulin in nonhepatotoxicity patients. For CYP2E1 c1/c1, c2/c2 and c1/c2 genotypes in INH-NH patients were 61.1%, 16.6% and 22.2% respectively while in INH-H patients 50.0%, 25.0% and 25.0% respectively. Conclusion: This study suggests that NAT-2 gene allele 4/4 was significantly higher in INH-induced hepatotoxicity as compared to nonhepatotoxicity group. There was no significant difference in CYP2E1 and GST genotypes between both the groups. Conflict of Interest: None 03_JCEH-Abstract.indd 39 3/18/2011 11:13:05 AM

Localization of Cytochrome P4502E1 Enzyme in Normal and Cancerous Gastric Mucosa and Association with Its Genetic Polymorphism in Unoperated and Remnant Stomach

Exposure to nitroso compounds and the activity of cytochrome P450 2E1 (CYP2E1), an activation enzyme for these carcinogens, are important factors in gastric carcinogenesis. Here, we investigated the potential correlation between genetic variation in CYP2E1 and its enzyme expression as detected with immunohistochemical (IHC) staining and cancer susceptibility in unoperated and remnant stomach. Expression of CYP2E1 in the stomach (n=117) was detected with IHC staining using a polyclonal anti-CYP2E1 antibody. Interindividual variation in CYP2E1 enzyme activity was then compared with genetic polymorphisms in the transcriptional flanking region of the CYP2E1 gene by restriction fragment length polymorphism (RFLP) detection using the Rsa I restriction enzyme. Genetic polymorphisms of Rsa I RFLP in CYP2E1 were investigated in 499 patients with gastric cancer (466 unoperated stomachs and 33 remnant stomachs) and 553 control patients with benign gastroduodenal diseases. Mucosal IHC staining for CYP2E1 was stronger in areas of intestinal metaplasia, particularly in endocrine cells, which stained consistently and strongly. Expression of CYP2E1 enzyme in areas of IHC staining were confirmed with Western blot analysis and showed a significant association between the degree of staining and the CYP2E1 genotype (p<0.01) in cancer tissues and in the foveolar epithelium of normal gastric mucosa. No association between specific CYP2E1 genotype and gastric cancer risk in the unoperated stomach was found in either the large study or the age- and gender-matched case-control study. However, the frequency of rare alleles (C1/C2 or C2/C2) was significantly higher in patients with cancer in the remnant stomach following gastrectomy than in controls subjects without cancer (odds ratio=2.8, 95% confidence interval=1.3-5.8) or those with primary gastric cancer (odds ratio=2.6, 95% confidence interval=1.3-5.5). CYP2E1 genetic polymorphisms might correlate with CYP2E1 enzyme expression levels in normal and cancerous gastric tissues. These polymorphisms do not influence the development of primary stomach cancer but may do so in specific conditions, such as the remnant stomach after gastrectomy.

Association of polymorphism in alcohol dehydrogenase and interaction with other genetic risk factors with alcoholic liver cirrhosis

The association of polymorphism of alcohol dehydrogenase ( ADH) and its interaction with genes involved in the generation and detoxification of free radicals such as cytochrome P4502E1 ( CYP2E1) and glutathione S-transferases M1 ( GSTM1) were studied with alcoholic liver cirrhosis. The study included 175 alcoholic cirrhotic patients, 140 non-alcoholic cirrhotic patients, 255 non-alcoholic controls and 140 alcoholic controls. Our data revealed that the ADH1C*1/*1 genotype exhibited significant association with alcoholic liver cirrhosis while ADH1B genotypes did not show any significant association. A much higher risk to alcoholic liver cirrhosis was observed in patients carrying a combination of wild genotypes of ADH1C ( ADH1C*1/*1) and variant genotype of ADH1B ( ADH1B*2/*2) or CYP2E1 ( CYP2E1*5B) or null genotype of GSTM1. Our data suggest a role for the interaction amongst the genes involved in metabolizing alcohol and in generating and detoxifying free radicals with susceptibility to alcoholic liver cirrhosis.