The genetic profiles of CYP1A1, CYP1A2 and CYP2E1 enzymes as susceptibility factor in xenobiotic toxicity in Turkish population

Coffee consumption is associated with a reduced risk of colorectal cancer recurrence and all-cause mortality

Coffee consumption has been associated with a reduced risk of developing colorectal cancer (CRC). However, it is not clear whether coffee consumption is related to CRC progression. Hence, we assessed the association of coffee consumption with CRC recurrence and all-cause mortality using data from a prospective cohort study of 1719 stage I-III CRC patients in the Netherlands. Coffee consumption and other lifestyle characteristics were self-reported using questionnaires at the time of diagnosis. We retrieved recurrence and all-cause mortality data from the Netherlands Cancer Registry and the Personal Records Database, respectively. Cox proportional hazard regression models with and without restricted cubic splines were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) adjusted for age, sex, education, smoking status, cancer stage and tumor location. We observed 257 recurrences during a 6.2-year median follow-up and 309 deaths during a 6.6-year median follow-up. Consuming more than 4 cups/d of coffee compared to an intake of <2 cups/d was associated with a 32% lower risk of CRC recurrence (95% CI: 0.49, 0.94,). The association between coffee consumption and all-cause mortality was U-shaped; coffee intake seemed optimal at 3-5 cups/d with the lowest risk at 4 cups/d (HR: 0.68, 95% CI: 0.53, 0.88). Our results suggest that coffee consumption may be associated with a lower risk of CRC recurrence and all-cause mortality. The association between coffee consumption and all-cause mortality appeared nonlinear. More studies are needed to understand the mechanism by which coffee consumption might improve CRC prognosis.

Analysis of CYP2J2 mutations in the Chinese Uyghur population

Genetic characteristics of CYP2J2 in different populations may be helpful to explore interethnic variability in drug response and disease susceptibility. There is no information about the genetic profile of CYP2J2 in the Chinese Uyghur population. We used PCR and first-generation sequencing technology to investigate CYP2J2 mutations in 100 unrelated healthy Chinese Uyghurs. The chi-square test was used to compare genotyping data of CYP2J2 in the Chinese Uyghur population with other ethnic groups. The SIFT and PolyPhen-2 online tools were used to predict the protein function of the novel nonsynonymous mutations in CYP2J2. CADD software was used to predict pathogenicity of the mutations. We found twenty-eight mutations in CYP2J2, five new mutations, three alleles (*1, *7 and *8), and three genotypes (*1/*1, *1/*7 and *1/*8) in the Chinese Uyghur population. The allele frequencies of CYP2J2 *1, *7 and *8 were 96%, 3.45%, and 0.5%, respectively. Interethnic comparison found that subgenotype *1 in Uyghur was significantly higher than in Taiwanese and African Americans, and *7 frequency in Uyghur was slightly lower than that in Taiwanese and African Americans (P<0.05); *8 was only found in Chinese Uyghur and Korean populations, with frequencies of 0.5% and 0.8%, respectively. Furthermore, the protein prediction results revealed that the five nonsynonymous mutations could influence protein structure and function. The observations of this study give rise to useful information on CYP2J2 mutations in Chinese Uyghurs, which may support future important clinical implications for the use of medications metabolized by CYP2J2.

Genetic Polymorphisms of Pesticide-Metabolizing Enzymes and Transporters in Agricultural Workers and Thyroid Hormone Levels

PURPOSE

Chronic exposure to pesticides has been associated with thyroid dysfunction owing to their endocrine disruption ability. Genetic variations in genes encoding phase I and II enzymes and phase III transporters are partly responsible for individual responses to chemical pesticides. This study investigated the association between variations in genes involved in pesticide metabolism and altered thyroid hormone concentrations.

METHODS

We assessed thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) in organic agriculture workers (n = 216) and workers who used chemical pesticides (n = 229). A questionnaire was used to collect sociodemographic, pesticide exposure, and health status data. Blood samples were analyzed for TSH, FT3, and FT4. Genomic DNA was extracted and genotyped using the TaqMan real-time PCR genotyping assay and restriction fragment length polymorphism method for 15 metabolically related genes.

RESULTS

Significant differences in the TSH (1.58 vs 1.12 µIU/mL) and FT3 (0.34 vs 0.31 ng/dL) concentrations between the chemical and organic worker groups were observed. The frequencies of all single nucleotide polymorphisms were in Hardy-Weinberg equilibrium and were mostly consistent with Asian populations. The findings showed the association between SNPs of enzymes and transporters and TSH, FT3, and FT4. The odd ratio and adjusted odd ratio (with sex, age, smoking status, alcohol consumption and exposure parameters) for subclinical thyroid disease by the variant alleles CYP1A1 rs1048943, CYP2B6 rs2279343, CYP2C19 rs4244285, NAT2 rs1799931, and PON1 rs662 in the chemical workers compared with the organic workers were found (P values < 0.05).

CONCLUSION

This is the first study to assess gene-environment interactions in Thai agricultural workers by investigating disruptions of the hypothalamic-pituitary-thyroid axis. The investigated SNP profiles revealed several gene-thyroid hormone associations in which even low levels of pesticide exposure could disturb thyroid homeostasis. These findings provide a foundation for planning future studies investigating associations between complex diseases and occupational pesticide exposure.

How Can Drug Metabolism and Transporter Genetics Inform Psychotropic Prescribing?

Many genetic variants in drug metabolizing enzymes and transporters have been shown to be relevant for treating psychiatric disorders. Associations are strong enough to feature on drug labels and for prescribing guidelines based on such data. A range of commercial tests are available; however, there is variability in included genetic variants, methodology, and interpretation. We herein provide relevant background for understanding clinical associations with specific variants, other factors that are relevant to consider when interpreting such data (such as age, gender, drug-drug interactions), and summarize the data relevant to clinical utility of pharmacogenetic testing in psychiatry and the available prescribing guidelines. We also highlight areas for future research focus in this field.

The Role of PON1 Variants in Disease Susceptibility in a Turkish Population

Paraoxonase 1 (PON1) enzyme plays a major role in antioxidant defense and protects the cells against reactive species. The most common PON1 Q192R and L55M polymorphisms are responsible for a wide variation of PON1 activity, which showed an up to 13-fold interindividual variation among the same genotype. PON1 genotypes were evaluated with the development of pancreatitis, colorectal cancer, and hypothyroidism in a hospital-based, case-control study. Individuals with rs662 G allele had a two-fold risk of developing hypothyroidism. A weak association was found between rs854560 T allele and pancreatitis. The results were preliminary. Further studies with a larger number and detailed biochemical parameters are needed.

Association of CYP19A1 and CYP1A2 genetic polymorphisms with type 2 diabetes mellitus risk in the Chinese Han population

Background

Type 2 diabetes mellitus (T2DM), one of the global health issues, is a group of metabolic diseases and is affected by several genetic loci in the clinical phenotype. This study intended to ascertain associations between CYP19A1 and CYP1A2 gene polymorphisms with the T2DM risk in Chinese Han.

Methods

Seven single nucleotide polymorphisms (SNPs) in total including five of CYP19A1 (rs4646, rs6493487, rs1062033, rs17601876 and rs3751599) and two of CYP1A2 (rs762551 and rs2470890) from 512 T2DM patients and 515 non-diabetic controls were genotyped in the platform of Agena MassARRAY. SPSS 18.0 was utilized for analyzing genotyping results. Logistic regression models were conducted for the risk assessment by the odds ratios (ORs) and 95% confidence intervals (CIs).

Results

The results suggested a significant association between genotype GC of rs1062033 with a decreased T2DM risk (OR = 0.73, 95% CI = 0.55–0.96, P = 0.025) under the co-dominant (heterozygous) model. The results of stratification analysis with age and gender adjustment revealed that the effects of all selected SNPs in CYP19A1 and CYP1A2 on the T2DM susceptibility were dependent on age, body mass index (BMI) and disease progression (P <  0.05). The haplotype analysis was further conducted and the results indicated that C_rs1062033G_rs17601876A_rs3751599 in CYP19A1 played a protective role (OR = 0.48, 95% CI = 0.25–0.91, P = 0.026) in T2DM patients with diabetic retinopathy.

Conclusion

This population-based case-control study suggested that CYP19A1 and CYP1A2 variations might affect the susceptibility of T2DM. The findings provide a theoretical basis for searching the clinical therapeutic markers and attractive drug targets of T2DM.

A comprehensive review of cytochrome P450 2E1 for xenobiotic metabolism

Cytochrome P450 2E1 (CYP2E1) plays a vital role in drug-induced hepatotoxicity and cancers (e.g. lung and bladder cancer), since it is responsible for metabolizing a number of medications and environmental toxins to reactive intermediate metabolites. CYP2E1 was recently found to be the highest expressed CYP enzyme in human livers using a proteomics approach, and CYP2E1-related toxicity is strongly associated with its protein level that shows significant inter-individual variability related to ethnicity, age, and sex. Furthermore, the expression of CYP2E1 demonstrates regulation by extensive genetic polymorphism, endogenous hormones, cytokines, xenobiotics, and varying pathological states. Over the past decade, the knowledge of pharmacology, toxicology, and biology about CYP2E1 has grown remarkably, but the research progress has yet to be summarized. This study presents a timely systematic review on CYP2E1's xenobiotic metabolism, genetic polymorphism, and inhibitors, with the focus on their clinical relevance for the efficacy and toxicity of various CYP2E1 substrates. Moreover, several knowledge gaps have been identified towards fully understanding the potential interactions among different CYP2E1 substrates in clinical settings. Through in-depth analyses of these knowns and unknowns, we expect this review will aid in future drug development and improve management of CYP2E1 related clinical toxicity.

A Predictive Model Assessing Genetic Susceptibility Risk at Workplace

(1) Background: The study of susceptibility biomarkers in the immigrant workforce integrated into the social tissue of European host countries is always a challenge, due to high individual heterogeneity and the admixing of different ethnicities in the same workplace. These workers having distinct cultural backgrounds, beliefs, diets, and habits, as well as a poor knowledge of the foreign language, may feel reluctant to donate their biological specimens for the biomonitoring research studies. (2) Methods: A model predicting ethnicity-specific susceptibility based on principal component analysis has been conceived, using the genotype frequency of the investigated populations available in publicly accessible databases. (3) Results: Correlations among ethnicities and between ethnic and polymorphic genes have been found, and low/high-risk profiles have been identified as valuable susceptibility biomarkers. (4) Conclusions: In the absence of workers’ consent or access to blood genotyping, ethnicity represents a good indicator of the subject’s genotype. This model, associating ethnicity-specific genotype frequency with the susceptibility biomarkers involved in the metabolism of toxicants, may replace genotyping, ensuring the necessary safety and health conditions of workers assigned to hazardous jobs.

Generation of a Tg(cyp1a-12DRE:EGFP) transgenic zebrafish line as a rapid in vivo model for detecting dioxin-like compounds

Dioxin-like compounds (DLCs) are extremely stable toxic organic compounds and can cause serious health risks. To develop a convenient biomonitoring tool for the detection of DLCs in the environment, we generated a transgenic line-Tg(cyp1a-12DRE:EGFP)-with a zebrafish cyp1a promoter recombined with multiple dioxin-responsive elements (DREs) that drive EGFP expression. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-induced EGFP expression was observed in the head cartilage (most sensitive), gut, otic vesicle, pectoral fin bud and eye of larvae. The lowest observed effect concentration of TCDD was estimated to be approximately 1 ng/L. Compared with existing zebrafish lines, our transgenic fish displayed comparable or even higher detection sensitivity to DLCs and could serve as an improved and rapid assay in an in vivo context. The Tg(cyp1a-12DRE:EGFP) transgenic zebrafish line also had higher stability for inducing EGFP expression (nearly 100% of our zebrafish induced EGFP at approximately 1 ng/L TCDD) than other lines. In addition, Tg(cyp1a-12DRE:EGFP) zebrafish could serve as a convenient and straightforward tool to assess potential cranial malformations and related health effects.

Polymorphisms of drug-metabolizing enzyme CYP2E1 in Chinese Uygur population

Pharmacogenetics is the genetic basis of pharmacokinetics, genetic testing, and clinical management in diseases. Evaluation about genetic alterations of drug metabolizing enzymes in human genome contributes toward understanding the interindividual and interethnic variability for clinical response to potential toxicants. CYP2E1 gene encodes a drug-metabolizing enzyme that metabolizes mostly small, polar molecules, including toxic laboratory chemicals. The aim of this study was to investigate CYP2E1 polymorphisms and gene profile in a Chinese Uygur population. Frequencies for the CYP2E1 mutated alleles and genotypes were screened in 100 unrelated random healthy Uygur volunteers. PCR and direct sequencing revealed a total of 32 polymorphisms, of which 5 novel mutations were presented. Rs 943975 was the most common single nucleotide polymorphism (SNP). The allele frequencies of CYP2E11A, 4, 7A, and 7C were 65.5, 2, 19.5, and 13%, respectively. The most common genotype combinations were CYP2C191A/1A (43%) and 1A/7C (24%). Functional prediction for 2 nonsynonymous mutations G173S and V179I was performed using MutationTaster, sorting intolerant from tolerant, and PolyPhen-2. The observations of the present study give rise to useful information on CYP2E1 polymorphisms in Chinese Uygur individuals. The results suggest important clinical implications for the use of medications metabolized by CYP2E1 among Uygurs.

Maternal and embryonic exposure to the water soluble fraction of crude oil or lead induces behavioral abnormalities in zebrafish (Danio rerio), and the mechanisms involved

The water-soluble fraction (WSF) of crude oil plays an important role in the toxicity of crude oil in aquatic environments. Heavy metals, such as lead (Pb) are also important environmental contaminants, which can reach aquatic systems via the effluents of industrial, urban and mining sources. In the present study, we investigated whether maternal and embryonic exposure to the WSF (5, 50 μg/L) or Pb (10, 100 μg/L) could induce behavioral abnormalities in zebrafish. Our results showed that maternal and embryonic exposure to the WSF (5, 50 μg/L) and Pb (10, 100 μg/L) induced swimming activity alterations in larval and juvenile zebrafish. In 15 days post-fertilization (dpf) larval zebrafish, the distance moved was significantly increased in the groups treated with the WSF (5, 50 μg/L), but the angular velocity and turn angle were decreased after treatment with the WSF (5, 50 μg/L) or Pb (10, 100 μg/L). In 30 dpf juvenile zebrafish, the distance moved was markedly decreased in both groups treated with the WSF (5, 50 μg/L) and the Pb (10 μg/L) group, but the percentage of zebrafish moving up and the inter-fish distance of two juvenile fish were increased after treatment with the WSF (5, 50 μg/L) or Pb (10, 100 μg/L). Maternal and embryonic exposure to the WSF (5, 50 μg/L) or Pb (10, 100 μg/L) likely impaired the brain neurons growth and induced behavioral abnormalities in the larval and juvenile zebrafish. Furthermore, the expressions of some key genes, which were associated with calcium channels, behavioral development or the metabolism of environmental contaminants, were changed.