Genetic polymorphisms of CYP2E1 and risk of colorectal cancer: the Fukuoka Colorectal Cancer Study

CYP2E1 C-1054T and 96-bp I/D genetic variations and risk of gestational diabetes mellitus in chinese women: a case-control study

BACKGROUND

Cytochrome P450 2E1 (CYP2E1) plays a key role in the metabolism of xenobiotic and endogenous low-molecular-weight compounds. This study aimed to determine if the genetic variations of 96-bp insertion/deletion (I/D) and C-1054T (rs2031920) in CYP2E1 were associated with the risk of gestational diabetes mellitus (GDM).

METHODS

CYP2E1 polymorphisms were genotyped in a case-control study of 1,134 women with uncomplicated pregnancies and 723 women with GDM. The effects of genotype on the clinical, metabolic, and oxidative stress indices were assessed.

RESULTS

The CYP2E1 C-1054T variant was associated with an increased risk of GDM based on the genotype, recessive, dominant, and allele genetic models (P < 0.05). The TT + CT genotype remained a significant predictive factor for GDM risk after correcting for maternal age and pre-pregnancy body mass index (OR = 1.277, 95% CI: 1.042-1.563, P = 0.018). Moreover, fasting insulin concentrations and homeostatic model assessment of insulin resistance were significantly higher in GDM patients carrying the T allele than in those with the CC genotype (P < 0.05). Furthermore, the combined genotype II + ID/TT + CT of the 96-bp I/D and C-1054T polymorphisms further increased the risk of GDM when the combined genotype DD/CC was set as the reference category (OR = 1.676, 95% CI: 1.182-2.376, P = 0.004).

CONCLUSIONS

The T allele of the C-1054T polymorphism and its combination with the I allele of the 96-bp I/D variation in CYP2E1 are associated with an increased risk of GDM in the Chinese population. The - 1054T allele may be associated with more serious insulin resistance in patients.

Association between CYP2E1 C-1054T and 96-bp I/D genetic variations and the risk of polycystic ovary syndrome in Chinese women

PURPOSE

To investigate the association of cytochrome P450 2E1 (CYP2E1) C-1054T (rs2031920) and 96-bp I/D genetic variations with the risk of polycystic ovary syndrome (PCOS), and to estimate the effects of genotypes on the clinical, metabolic, hormonal, and oxidative stress indicators.

METHODS

This case-control study included 762 control women and 1034 patients with PCOS. Genotypes were determined using polymerase chain reaction and/or restriction fragment length polymorphism analysis. Clinical and biochemical parameters were also analyzed.

RESULTS

Frequencies of the TT + CT genotype (35.4 vs. 28.9%) and T allele (19.6 vs. 16.0%) of the CYP2E1 C-1054T polymorphism were significantly higher in the PCOS group than in the control group (OR = 1.350, 95% CI 1.103-1.652, P = 0.004 for the dominant model). Genotype TT + CT remained a significant predictor of PCOS in a logistic regression model including age, body mass index (BMI), and recruitment year of participants (OR = 1.345, 95% CI 1.071-1.688, P = 0.011). No statistical differences were found in the genotype and allele frequencies of CYP2E1 96-bp I/D polymorphism. However, the combined genotype DD/TT + CT was related to an increased risk of PCOS when the DD/CC wild-type combined genotype was used as a reference. Patients with the I allele of 96-bp I/D polymorphism had a lower BMI but higher plasma apolipoprotein B and oxidized low-density lipoprotein cholesterol levels than those with the DD genotype.

CONCLUSION

CYP2E1 C-1054T, but not 96-bp I/D, genetic polymorphism is associated with an increased risk of PCOS in Chinese women.

Association between CYP2E1 polymorphisms and colorectal cancer risk: a systematic review and meta-analysis

CYP2E1 encodes an enzyme that participates in the activation of several carcinogenic substances. Thus, numerous studies have investigated the association between CYP2E1 polymorphisms and colorectal cancer (CRC) risk, but inconclusive results have been obtained. We performed a meta-analysis to precisely evaluate the relationship of CYP2E1 rs2031920, rs3813867, and rs6413432 polymorphisms with the susceptibility to CRC. Scopus, Web of Science and PubMed databases were searched to identify eligible studies, and the association between the polymorphisms and CRC risk was then quantitatively synthesized using different genetic models. Eighteen studies with 23,598 subjects were selected for inclusion into the analysis. Significant association between rs2031920 and an increased CRC risk was observed in homozygous (OR = 1.496, 95% CI 1.177-1.901, P = 0.001), recessive (OR = 1.467, 95% CI  1.160-1.857, P = 0.001) and allele (OR = 1.162, 95% CI  1.001-1.349, P = 0.048) models. Significant association was not found for rs3813867 and rs6413432 (P > 0.05). In conclusion, our results suggest that rs2031920, but not rs3813867 and rs6413432, is associated with the risk of CRC.

The Search for Cancer Biomarkers: Assessing the Distribution of INDEL Markers in Different Genetic Ancestries

Cancer is a multifactorial group of diseases, being highly incident and one of the leading causes of death worldwide. In Brazil, there is a great variation in cancer incidence and impact among the different geographic regions, partly due to the genetic heterogeneity of the population in this country, composed mainly by European (EUR), Native American (NAM), African (AFR), and Asian (ASN) ancestries. Among different populations, genetic markers commonly present diverse allelic frequencies, but in admixed populations, such as the Brazilian population, data is still limited, which is an issue that might influence cancer incidence. Therefore, we analyzed the allelic and genotypic distribution of 12 INDEL polymorphisms of interest in populations from the five Brazilian geographic regions and in populations representing EUR, NAM, AFR, and ASN, as well as tissue expression in silico. Genotypes were obtained by multiplex PCR and the statistical analyses were done using R, while data of tissue expression for each marker was extracted from GTEx portal. We highlight that all analyzed markers presented statistical differences in at least one of the population comparisons, and that we found 39 tissues to be differentially expressed depending on the genotype. Here, we point out the differences in genotype distribution and gene expression of potential biomarkers for risk of cancer development and we reinforce the importance of this type of study in populations with different genetic backgrounds.

M2PP: a novel computational model for predicting drug-targeted pathogenic proteins

BACKGROUND

Detecting pathogenic proteins is the origin way to understand the mechanism and resist the invasion of diseases, making pathogenic protein prediction develop into an urgent problem to be solved. Prediction for genome-wide proteins may be not necessarily conducive to rapidly cure diseases as developing new drugs specifically for the predicted pathogenic protein always need major expenditures on time and cost. In order to facilitate disease treatment, computational method to predict pathogenic proteins which are targeted by existing drugs should be exploited.

RESULTS

In this study, we proposed a novel computational model to predict drug-targeted pathogenic proteins, named as M2PP. Three types of features were presented on our constructed heterogeneous network (including target proteins, diseases and drugs), which were based on the neighborhood similarity information, drug-inferred information and path information. Then, a random forest regression model was trained to score unconfirmed target-disease pairs. Five-fold cross-validation experiment was implemented to evaluate model's prediction performance, where M2PP achieved advantageous results compared with other state-of-the-art methods. In addition, M2PP accurately predicted high ranked pathogenic proteins for common diseases with public biomedical literature as supporting evidence, indicating its excellent ability.

CONCLUSIONS

M2PP is an effective and accurate model to predict drug-targeted pathogenic proteins, which could provide convenience for the future biological researches.

CYP2E1 Polymorphisms and Colorectal Cancer

Background: The hepatic cytochrome P450 2E1 (CYP2E1) enzyme plays an important role in the metabolic activation of nitrosamines and other carcinogenic compounds. Aim of the study: To determine the effect of chemotherapy and radiation for colorectal cancer patients on some biochemical and molecular parameters. Patients and methods: The current study was conducted in the Department of Biology at the College of Science at the University of Al-Qadisiyah and in cooperation with the Cancer Center in the Najaf city and the Department of Medicine City in Baghdad, Iraq during the period from November 15, 2019, to May 6, 2020. The study group included a total of (90) samples were taken from males and females of ages ranged between (33 years to 80 years) and then it was divided into two groups. The first included (60) samples of people with colorectal cancer (CRC), and the second included (30) samples of people The healthy ones represented the control group. (5ml) of venous blood was withdrawn and the sample was divided into two groups, the first was placed in tubes containing an anti-clotting substance for molecular examination and kept at a temperature (-20) until use, and the other part was placed in Gel tube tubes and then placed in a centrifuge to separate Serum, for the purpose of biochemical examinations. With regard to the results of the values of oxidative stress indicators (SOD, GSH, MDA). Results: there was a significant difference in the level of (SOD, GSH) between the control and treatment groups, where the highest percentage was in the control group, followed by the radiotherapy group and then chemotherapy. The results showed a significant increase in the MDA value of the chemotherapy group compared with the radiotherapy and control group. The results of the molecular study to study the genotypes of the CYPIE2 gene showed that the C1/C1 type is the normal type for the CYPIE2 gene and that the ratio of this type did not show any significant difference between the groups, while the C2/C2 type showed no significant difference between the groups and the C2/C2 type. Conclusion: It can be concluded that the use of radiotherapy and chemotherapy to treat patients with CRC cancer has a clear effect on health and on many of the patient's physiological and biochemical indicators, and this, in turn, is reflected in the patient's ability to fight the disease.

Effects of gene polymorphisms of metabolic enzymes on the association between red and processed meat consumption and the development of colon cancer; a literature review

The role of environmental factors and genetic susceptibility in the development of colon cancer (CC) has been already proven, but the role of gene polymorphisms in modifying the risk of environmental factors such as nutritional factors is still unknown. This study aimed to investigate the effect of polymorphisms of involved genes in the association between red meat consumption and the development of CC. The present review was carried out using keywords such as polymorphism and/or protein and/or red meat and/or processed meat and/or colon cancer. PubMed and Science Direct databases were used to collect all related articles published from 2001 to 2017. The presence of SNP in the coding genes of proteins involved in metabolism of nutrients could play significant roles in the extent of the effects of nutrition in the development of CC. The effect of dietary proteins greatly depends on the polymorphisms in the metabolising genes of these substances. Gene polymorphisms may have a role in colorectal cancer risk, especially in people with high meat intake, and this leads to a difference in the effects of meat consumption in different individuals. To conclude, dietary recommendations for the prevention and control of CC should be modified based on the genotype of different individuals. Increasing our knowledge on this field of nutritional genomics can lead to personalised preventive and therapeutic recommendations for CC patients.

CYP1A1, CYP2E1 and EPHX1 polymorphisms in sporadic colorectal neoplasms

AIM

To investigate the contribution of polymorphisms in the CYP1A1, CYP2E1 and EPHX1 genes on sporadic colorectal cancer (SCRC) risk.

METHODS

Six hundred forty-one individuals (227 patients with SCRC and 400 controls) were enrolled in the study. The variables analyzed were age, gender, tobacco and alcohol consumption, and clinical and histopathological tumor parameters. The CYP1A1*2A, CYP1A1*2C CYP2E1*5B and CYP2E1*6 polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The EPHX1 Tyr113His, EPHX1 His139Arg and CYP1A1*2C polymorphisms were detected by real-time PCR. Chi-squared test and binary logistic regression were used in the statistical analysis. Haplotype analysis was conducted using the Haploview program, version 2.05.

RESULTS

Age over 62 years was a risk factor for SCRC development (OR = 7.54, 95%CI: 4.94-11.50, P < 0.01). Male individuals were less susceptible to SCRC (OR = 0.55, 95%CI: 0.35-0.85, P < 0.01). The CYP2E1*5B polymorphism was associated with SCRC in the codominant (heterozygous genotype: OR = 2.66, 95%CI: 1.64-4.32, P < 0.01), dominant (OR = 2.82, 95%CI: 1.74-4.55, P < 0.01), overdominant (OR = 2.58, 95%CI: 1.59-4.19, P < 0.01), and log-additive models (OR = 2.84, 95%CI: 1.78-4.52, P < 0.01). The CYP2E1*6 polymorphism was associated with an increased SCRC risk in codominant (heterozygous genotype: OR = 2.81, 95%CI: 1.84-4.28, P < 0.01; homozygous polymorphic: OR = 7.32, 95%CI: 1.85-28.96, P < 0.01), dominant (OR = 2.97, 95%CI: 1.97-4.50, P < 0.01), recessive (OR = 5.26, 95%CI: 1.35-20.50, P = 0.016), overdominant (OR = 2.64, 95%CI: 1.74-4.01, P < 0.01), and log-additive models (OR = 2.78, 95%CI: 1.91-4.06, P < 0.01). The haplotype formed by the minor alleles of the CYP2E1*5B (C) and CYP2E1*6 (A) polymorphisms was associated with SCRC (P = 0.002). However, the CYP1A1*2A, CYP1A1*2C, EPHX1 Tyr113His and EPHX1 His139Arg polymorphisms were not associated with SCRC.

CONCLUSION

In conclusion, the results demonstrated that CYP2E1*5B and CYP2E1*6 minor alleles play a role in the development of SCRC.

Associations between vitamin D receptor (VDR) gene polymorphisms and colorectal cancer risk and effect modifications of dietary calcium and vitamin D in a Japanese population

Much interest has been drawn to possible associations between vitamin D receptor (VDR) gene polymorphisms and colorectal cancer risk in conjunction with potentially protective effects of calcium and vitamin D. In a study of 685 cases of colorectal cancer and 778 community controls in Japan, we examined the associations of the FokI, BsmI, ApaI, and TaqI polymorphisms with colorectal cancer risk and effect modification by dietary calcium and vitamin D. Genotypes were determined by the PCR-RFLP method. The ApaI polymorphism seemed to be associated with a decreased risk of colorectal cancer, particularly of rectal cancer. The adjusted odds ratio of colorectal cancer for the ApaI AA and Aa genotypes combined versus the aa genotype was 0.83 (95% confidence interval [CI] 0.67-1.02), and the corresponding value for rectal cancer was 0.75 (95%CI 0.56-0.99). A decreased risk of colorectal cancer for the ApaI AA and Aa genotypes combined was more evident in individuals with high calcium intake (interaction p=0.055). The FokI polymorphism seemed to be associated with a decreased risk of colon cancer among those with high vitamin D intake (interaction p=0.09). The BsmI and TaqI polymorphisms were unrelated to colorectal cancer risk, and the null associations were not modified by calcium or vitamin D intake. In conclusion, the ApaI polymorphism may be associated with a decreased risk of colorectal cancer in Japanese, dependent on dietary calcium intake.

Moderate Alcohol Consumption and Colorectal Cancer Risk

BACKGROUND

Heavy alcohol drinking is a risk factor for colorectal cancer (CRC); previous studies have shown a linear dose-dependent association between alcohol intake and CRC. However, some studies suggest that moderate alcohol consumption may have a protective effect, similar to that seen in cardiovascular disease. Other factors may interact with alcohol and contribute additional risk for CRC. We aimed to determine the association between moderate alcohol consumption, limited to 30 g of alcohol per day, by beverage type on CRC risk and to assess the effects of other factors that interact with alcohol to influence CRC risk.

METHODS

The PubMed database was used to find articles published between 2008 and 2014 related to alcohol and CRC. Twenty-one relevant articles were evaluated and summarized, including 11 articles reporting on CRC risk associated with moderate intake and 10 articles focusing on genetic interactions associated with alcohol and CRC risk.

RESULTS

The association between alcohol and increased risk for CRC was found when intakes exceeded 30 g/d alcohol. Nonsignificant results were consistently reported for intakes <30 g/d. Additional risks for CRC were found to be related to obesity and folate status for regular alcohol consumers. Some significant results suggest that the development of CRC is dependent on the interaction of gene and environment.

CONCLUSIONS

The association between the amount of alcohol consumed and the incidence of CRC was not significant at moderate intake levels. Moderate alcohol consumption was associated with a reduced CRC risk in study populations with greater adherence to a Mediterranean diet, where wine contributed substantially to the alcoholic beverage consumed. Other factors such as obesity, folate deficiency, and genetic susceptibility may contribute additional CRC risk for those consuming alcohol. To minimize CRC risk, appropriate recommendations should encourage intakes below 30 g of alcohol each day.

Transgenic mouse models for alcohol metabolism, toxicity, and cancer

Alcohol abuse leads to tissue damage including a variety of cancers; however, the molecular mechanisms by which this damage occurs remain to be fully understood. The primary enzymes involved in ethanol metabolism include alcohol dehydrogenase (ADH), cytochrome P450 isoform 2E1, (CYP2E1), catalase (CAT), and aldehyde dehydrogenases (ALDH). Genetic polymorphisms in human genes encoding these enzymes are associated with increased risks of alcohol-related tissue damage, as well as differences in alcohol consumption and dependence. Oxidative stress resulting from ethanol oxidation is one established pathogenic event in alcohol-induced toxicity. Ethanol metabolism generates free radicals, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), and has been associated with diminished glutathione (GSH) levels as well as changes in other antioxidant mechanisms. In addition, the formation of protein and DNA adducts associated with the accumulation of ethanol-derived aldehydes can adversely affect critical biological functions and thereby promote cellular and tissue pathology. Animal models have proven to be valuable tools for investigating mechanisms underlying pathogenesis caused by alcohol. In this review, we provide a brief discussion on several animal models with genetic defects in alcohol-metabolizing enzymes and GSH-synthesizing enzymes and their relevance to alcohol research.

Interactions between meat intake and genetic variation in relation to colorectal cancer

Meat intake is associated with the risk of colorectal cancer. The objective of this systematic review was to evaluate interactions between meat intake and genetic variation in order to identify biological pathways involved in meat carcinogenesis. We performed a literature search of PubMed and Embase using “interaction”, “meat”, “polymorphisms”, and “colorectal cancer”, and data on meat–gene interactions were extracted. The studies were divided according to whether information on meat intake was collected prospectively or retrospectively. In prospective studies, interactions between meat intake and polymorphisms in PTGS2 (encoding COX-2), ABCB1, IL10, NFKB1, MSH3, XPC (P_int = 0.006, 0.01, 0.04, 0.03, 0.002, 0.01, respectively), but not IL1B, HMOX1, ABCC2, ABCG2, NR1I2 (encoding PXR), NR1H2 (encoding LXR), NAT1, NAT2, MSH6, or MLH1 in relation to CRC were found. Interaction between a polymorphism in XPC and meat was found in one prospective and one case–control study; however, the directions of the risk estimates were opposite. Thus, none of the findings were replicated. The results from this systematic review suggest that genetic variation in the inflammatory response and DNA repair pathway is involved in meat-related colorectal carcinogenesis, whereas no support for the involvement of heme and iron from meat or cooking mutagens was found. Further studies assessing interactions between meat intake and genetic variation in relation to CRC in large well-characterised prospective cohorts with relevant meat exposure are warranted.

Interleukin-6 mediated upregulation of CYP1B1 and CYP2E1 in colorectal cancer involves DNA methylation, miR27b and STAT3

Background:

The pro-inflammatory cytokine interleukin-6 (IL6) promotes colorectal cancer (CRC) development. It is also known to regulate cytochrome P450 (CYP450) enzymes, which are involved in CRC tumour initiation and promotion via activation of chemical carcinogens. Here, IL6 regulation of CYP450 expression was investigated in CRC.

Methods:

The effect of IL6 on CYP 1A1, 1B1 and 2E1 expression was determined in vitro using CRC cell lines HCT116 and SW480, and CYP450 expression was determined by immunohistochemistry in CRC tissues previously shown to have increased levels of IL6.

Results:

In mechanistic studies, IL6 treatment significantly induced CYP1B1 and CYP2E1, but not CYP1A1, gene expression in HCT116 and SW480 cells. CYP2E1 expression regulation occurred via a transcriptional mechanism involving STAT3. For CYP1B1 regulation, IL6 downregulated the CYP1B1-targeting microRNA miR27b through a mechanism involving DNA methylation. In clinical samples, the expression of CYP1B1 and CYP2E1, but not CYP1A1, was significantly increased in malignant tissue overexpressing IL6 compared with matched adjacent normal tissue.

Conclusions:

Colonic inflammation with the presence of IL6 associated with neoplastic tissue can alter metabolic competency of epithelial cells by manipulating CYP2E1 and CYP1B1 expression through transcriptional and epigenetic mechanisms. This can lead to increased activation of dietary carcinogens and DNA damage, thus promoting colorectal carcinogenesis.

Large-scale profiling of metabolic dysregulation in ovarian cancer

Ovarian cancer is the leading cause of death in gynecologic malignancies. Profiling of endogenous metabolites has potential to identify changes caused by cancer and provide inspiring insights into cancer metabolism. To systematically investigate ovarian cancer metabolism, we performed metabolic profiling of 448 plasma samples related to epithelial ovarian cancer (EOC) based on ultra-performance liquid chromatography mass spectrometry in both positive and negative modes. These unbiased metabolomic profiles could well distinguish EOC from benign ovarian tumor (BOT) and uterine fibroid (UF). Fifty-three metabolites were identified as specific biomarkers for EOC, and this is the first report of piperine, 3-indolepropionic acid, 5-hydroxyindoleacetaldehyde and hydroxyphenyllactate as metabolic biomarkers of EOC. The AUC values of these metabolites for discriminating EOC from BOT/UF and early-stage EOC from BOT/UF were 0.9100/0.9428 and 0.8385/0.8624, respectively. Meanwhile, our metabolites were able to distinguish early-stage EOC from late-stage EOC with an AUC of 0.8801. Importantly, analysis of dysregulated metabolic pathways extends our current understanding of EOC metabolism. Metabolic pathways in EOC patients are mainly characterized by abnormal phospholipid metabolism, altered l-tryptophan catabolism, aggressive fatty acid β-oxidation and aberrant metabolism of piperidine derivatives. Together, these metabolic pathways provide a foundation to support cancer development and progression. In conclusion, our large-scale plasma metabolomics study yielded fundamental insights into dysregulated metabolism in ovarian cancer, which could facilitate clinical diagnosis, therapy, prognosis and shed new lights on ovarian cancer pathogenesis.

RsaI but not DraI polymorphism in CYP2E1 gene increases the risk of gastrointestinal cancer in Malaysians: a case-control study

OBJECTIVES

Our study aimed to investigate the association of CYP2E1 C-1019T RsaI and T7678A DraI polymorphisms and factors such as age, gender and ethnicity to the risk of gastrointestinal cancer (GIC) in Malaysians.

DESIGN

Case-control study.

SETTING

Malaysia.

PARTICIPANTS

520 consented healthy blood donors with no previous GIC record and 175 patients with GIC.

MEASUREMENTS

C-1019T RsaI and T7678A DraI genotyping of CYP2E1 gene; direct sequencing.

RESULTS

This study reveals that the variant c2 allele and carrier with at least one c2 allele of C-1019T single nucleotide polymorphism (SNP) significantly increased the risk of GIC but no significant association was found between T7678A SNP and combined analysis of C-1019T and T7678A SNPs to risk of GIC. The Malaysian Chinese had greater risk of GIC compared with the Malays, Indians and KadazanDusun. An increased risk of GIC was observed in individuals aged >40 years and women had a 2.22-fold and 1.58-fold increased risk of stomach and colorectal cancers, respectively, when compared with men.

LIMITATIONS

The future research should be conducted with a larger sample population and including the gene-gene and gene-environmental interactions.

CONCLUSIONS

Our study suggests that the rare c2 allele and carrier with at least one c2 allele of CYP2E1 RsaI polymorphism significantly elevated the risk of GIC and may be used as a genetic biomarker for early screening of GIC in Malaysians. The risk age-group has been shifted to a younger age at 40s and women showed a significant greater risk of stomach and colorectal cancers than men.

Associations of CYP2E1 rs2031920 and rs3813867 polymorphisms with colorectal cancer risk: a systemic review and meta-analysis

Cytochrome P450 2E1 (CYP2E1) is a natural enzyme involved in the metabolic activation of many carcinogens, and the functional polymorphisms in the CYP2E1 gene might have impacts on colorectal cancer risk. Many studies were published to assess the associations of CYP2E1 rs2031920 and rs3813867 polymorphisms with colorectal cancer risk, but no consistent findings were reported. A systemic review and meta-analysis of eligible studies was performed to comprehensively assess the associations above. Odds ratios (ORs) with 95 % confidence interval (95 % CIs) were used to assess the strength of the associations. Seventeen studies from 15 publications with 17,082 individuals were finally included into this meta-analysis. Meta-analysis of the 13 studies on CYP2E1 rs2031920 polymorphism showed that there was a significant association between CYP2E1 rs2031920 polymorphism and colorectal cancer risk under two genetic models (c2 versus c1: OR = 1.19, 95 % CI 1.03-1.37, P = 0.022; c2c2/c2c1 versus c1c1: OR = 1.16, 95 % CI 1.00-1.35, P = 0.046). Meta-analysis of those four case-control studies on CYP2E1 rs3813867 polymorphism showed that there was no significant association between CYP2E1 rs3813867 polymorphism and colorectal cancer risk under all contrast models (c2 versus c1: OR = 0.96, 95 % CI 0.80-1.16, P = 0.672; c2c2 versus c1c1: OR = 1.26, 95 % CI 0.43-3.67, P = 0.672; c2c2/c1c2 versus c1c1: OR = 0.95, 95 % CI 0.78-1.16, P = 0.114; and c2c2 versus c1c2/c1c1: OR = 1.17, 95 % CI 0.41-3.36, P = 0.775). Therefore, the findings from this meta-analysis suggest that CYP2E1 rs2031920 polymorphism is associated with colorectal cancer risk, but CYP2E1 rs3813867 polymorphism is not associated with colorectal cancer risk. In addition, more well-designed studies with large sample size are needed to provide a more precise evaluation on the associations above.

CYP2E1 T7632A and 9-bp insertion polymorphisms and colorectal cancer risk: a meta-analysis based on 4,592 cases and 5,918 controls

Previous studies suggest that genetic factors play important roles in the development of colorectal cancer. CYP2E1 T7632A and 9-bp insertion polymorphisms may influence the risk of colorectal cancer, but published results are conflicting. We therefore conducted a meta-analysis comprising 9 case-control studies with 4,592 cases and 5,918 controls. Odds ratios (ORs) with 95 % confidence interval (95 % CI) were used to assess the strength of the associations of CYP2E1 T7632A and 9-bp insertion polymorphisms with colorectal cancer. For CYP2E1 T7632A polymorphism, meta-analysis showed that there was no significant association between the CYP2E1 T7632A polymorphism and colorectal cancer risk under all contrast models (A vs. T: OR = 1.06, 95 % CI 0.88-1.29, P = 0.528; AA vs. TT: OR = 0.85, 95 % CI 0.61-1.19, P = 0.351; AA/TA vs. TT: OR = 1.08, 95 % CI 0.87-1.34, P = 0.484; and AA vs.

TT/TA

OR = 0.87, 95 % CI 0.62-1.21, P = 0.395). For CYP2E1 96-bp insertion polymorphism, meta-analysis showed that there was a significant association between the CYP2E1 96-bp insertion polymorphism and colorectal cancer risk under the allele contrast model and the dominant contrast model (for the allele contrast model: OR = 1.20, 95 % CI 1.06-1.36, P = 0.005; for the dominant contrast model: OR = 1.25, 95 % CI 1.07-1.45, P = 0.005). Subgroup analysis by race suggested that there was an obvious association between the CYP2E1 96-bp insertion polymorphism and colorectal cancer risk in Asians under the codominant contrast model. In conclusion, our meta-analysis demonstrates that there is a significant association between the CYP2E1 96-bp insertion polymorphism and colorectal cancer risk, and CYP2E1 9-bp insertion polymorphism is a risk factor for developing colorectal cancer.

CYP2E1 polymorphisms and colorectal cancer risk: a HuGE systematic review and meta-analysis

Studies investigating the associations between Cytochrome P4502E1 (CYP2E1) polymorphisms and colorectal cancer (CRC) risk report conflicting results. We conducted a meta-analysis to assess the association between CYP2E1 gene Rsa I/Pst I, Dral T/A and 96-bp insertion polymorphisms and CRC susceptibility. Two investigators independently searched the Medline, Embase, CNKI, Wanfang, and Chinese Biomedicine Databases. Summary odds ratios (ORs) and 95 % confidence intervals (95 % CIs) for CYP2E1 polymorphisms and CRC were calculated in a fixed-effect model (the Mantel-Haenszel method) and a random-effects model (the DerSimonian and Laird method) when appropriate. Ultimately, 12, 5, and 4 studies were found to be eligible for meta-analyses of Rsa I/Pst I, Dral T/A, and 96-bp insertion polymorphisms, respectively. Our analysis suggested that the variant genotype of Rsa I/Pst I were associated with a significantly increased CRC risk (c2/c2 vs. c1/c1, OR = 1.36, 95 % CI = 1.04-1.77; recessive model, OR = 1.35, 95 % CI = 1.04-1.75). Moreover, similar results were observed between CYP2E1 96-bp insertion polymorphism and CRC risk (dominant model, OR = 1.25, 95 % CI = 1.07-1.45), while no association was observed between CYP2E1 Dral T/A polymorphism and CRC susceptibility in any genetic model. No publication bias was found in the present study. This meta-analysis shows that CYP2E1 Rsa I/Pst I and 96-bp insertion polymorphisms may be associated with CRC risk. The CYP2E1 Dral T/A polymorphism was not detected to be related to the risk for CRC.

High-fat diet alters gene expression in the liver and colon: links to increased development of aberrant crypt foci

BACKGROUND

Obesity is associated with an increased risk of colon cancer. High-fat diets that lead to obesity may be a contributing factor, but the mechanisms are unknown.

AIMS

This study examines susceptibility to azoxymethane (AOM)-induced precancerous lesions in mice in response to consumption of either a low or a high-fat diet and associated molecular changes in the liver and colon.

METHODS

Gene markers of xenobiotic metabolism, leptin-regulated inflammatory cytokines and proliferation were assessed in liver and colon in response to high-fat feeding to determine links with increased sensitivity to AOM.

RESULTS

High-fat feeding increased development of AOM-induced precancerous lesions and was associated with increased CYP2E1 gene expression in the liver, but not the colon. Leptin receptors and the colon stem cell marker (Lgr5) were down-regulated in the proximal colon, with a corresponding up-regulation of the inflammatory cytokine (IL6) in response to high-fat feeding. Notably in the distal colon, where aberrant crypt foci develop in response to AOM, the proliferative stem cell marker, Lgr5, was significantly up-regulated with high-fat feeding.

CONCLUSIONS

The current study provides evidence that high-fat diets can alter regulation of molecular markers of xenobiotic metabolism that may expose the colon to carcinogens, in parallel with activation of β-catenin-regulated targets regulating colon epithelial cells. High-fat diets associated with obesity may alter multiple molecular factors that act synergistically to increase the risk of colon cancer associated with obesity.

Meat-related mutagen exposure, xenobiotic metabolizing gene polymorphisms and the risk of advanced colorectal adenoma and cancer

Meat mutagens, including heterocyclic amines (HCAs), polycyclic aromatic hydrocarbons (PAHs) and N-nitroso compounds (NOCs), may be involved in colorectal carcinogenesis depending on their activation or detoxification by phase I and II xenobiotic metabolizing enzymes (XME). Using unconditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI), we examined the intake of five meat mutagens and >300 single nucleotide polymorphisms (SNPs) in 18 XME genes in relation to advanced colorectal adenoma (1205 cases and 1387 controls) and colorectal cancer (370 cases and 401 controls) within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Dietary intake of meat mutagens was assessed using a food frequency questionnaire with a detailed meat-cooking module. An interaction was observed between 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) intake and the NAT1 polymorphism rs6586714 in the adenoma study (P(interaction) = 0.001). Among individuals carrying a GG genotype, high MeIQx intake was associated with a 43% increased risk of adenoma (95% CI 1.11-1.85, P(trend) = 0.07), whereas the reverse was observed among carriers of the A variant (OR = 0.50, 95% CI 0.30-0.84, P(trend) = 0.01). In addition, we observed some suggestive (P < 0.05) modifying effects for SNPs in other XME genes (UGT1A, CYP2E1, EPHX1, AHR and GSTM3), but these were not significant after adjustment for multiple testing. This large and comprehensive study of XME genes, meat mutagens and the risk of colorectal tumours found that a NAT1 polymorphism modified the association between MeIQx intake and colorectal adenoma risk.

Microsomal epoxide hydrolase polymorphisms, cigarette smoking, and risk of colorectal cancer: the Fukuoka Colorectal Cancer Study

Microsomal epoxide hydrolase (EPHX1) plays an important role in the activation and detoxification of polycyclic aromatic hydrocarbons, carcinogens found in cigarette smoke. Polymorphisms in exon 3 (Y113H) and exon 4 (H139R) of the EPHX1 have been associated with enzyme activity. We investigated the risk of colorectal cancer in relation to the EPHX1 Y113H and H139R polymorphisms and assessed effect modifications of cigarette smoking and the other covariates. The interaction between the EPHX1 polymorphisms and selected genetic polymorphisms was also examined. We used data from Fukuoka Colorectal Cancer Study, a community-based case-control study, including 685 cases and 778 controls. In-person interviews were conducted to assess lifestyle factors. The EPHX1 Y113H and H139R polymorphisms were determined by the TaqMan assay and the polymerase chain reaction-restriction fragment length polymorphism, respectively. Neither of the two polymorphisms nor the imputed EPHX1 phenotype was associated with colorectal cancer risk. Cigarette smoking and alcohol intake showed no effect modification on the association with the EPHX1 polymorphisms or the imputed EPHX1 phenotype. Increased risks of colorectal cancer associated with the 113Y allele and imputed EPHX1 phenotype were observed among individuals with high body mass index (BMI; ≥25.0 kg/m(2)), but not among those with low BMI (<25.0 kg/m(2)). The risk decreased with an increasing number of the 139R allele in the null genotypes of GSTM1/GSTT1. It is unlikely that the EPHX1 polymorphisms play an important role in colorectal carcinogenesis. The observed interactions of the EPHX1 polymorphisms with BMI and the GSTM1/GSTT1 genotypes warrant further investigation.

Genetic polymorphisms of genes coding to alcohol-metabolizing enzymes in western Mexicans: association of CYP2E1*c2/CYP2E1*5B allele with cirrhosis and liver function

BACKGROUND

Alcoholic cirrhosis constitutes a major public health problem in the world where ADH1B, ALDH2, and CYP2E1 polymorphisms could be playing an important role. We determined ADH1B*2, ALDH2*2, and CYP2E1*c2 allele frequencies in healthy control individuals (C) and patients with alcoholic cirrhosis (AC) from western Mexico.

METHODS

Ninety C and 41 patients with AC were studied. Genotype and allele frequency were determined through polymerase chain reaction-restriction fragment length polymorphisms.

RESULTS

Polymorphic allele distribution in AC was 1.6%ADH1B*2, 0.0%ALDH2*2, and 19.5%CYP2E1*c2; in C: 6.1%ADH1B*2, 0%ALDH2*2, and 10.6%CYP2E1*c2. CYP2E1*c2 polymorphic allele and c1/c2 genotype frequency were significantly higher (p < 0.05 and p < 0.01, respectively) in patients with AC when compared to C. Patients with AC, carrying the CYP2E1*c2 allele, exhibited more decompensated liver functioning evaluated by total bilirubin and prothrombin time, than c1 allele carrying patients (p < 0.05). Cirrhosis severity, assessed by Child's Pugh score and mortality, was higher in patients carrying the c2 allele, although not statistically significant.

CONCLUSIONS

In this study, CYP2E1*c2 allele was associated with susceptibility to AC; meanwhile, ADH1B*2 and ALDH2*2 alleles were not. CYP2E1*c2 allele was associated with AC severity, which could probably be attributed to the oxidative stress promoted by this polymorphic form. Further studies to clearly establish CYP2E1*c2 clinical relevance in the development of alcohol-induced liver damage and its usefulness as a probable prognostic marker, should be performed. Also, increasing the number of patients and including a control group conformed by alcoholic patients free of liver damage may render more conclusive results. These findings contribute to the understanding of the influence of gene variations in AC development among populations, alcohol metabolism, and pharmacogenetics.

Independent and combined effects of ethanol self-administration and nicotine treatment on hepatic CYP2E1 in African green monkeys

Cytochrome P450 2E1 metabolizes ethanol and also bioactivates many toxins and procarcinogens. Elevated levels of hepatic CYP2E1 are associated with an increased susceptibility to chemical toxicity and carcinogenesis. This study investigated the induction of hepatic CYP2E1 by ethanol and nicotine, alone and in combination, in a nonhuman primate model. Monkeys that self-administered ethanol and that received subcutaneous injections of nicotine (0.5 mg/kg b.i.d.), alone and in combination, were compared with control animals (four groups, n = 10/group). Chlorzoxazone (CZN) was used as a probe drug to phenotype in vivo CYP2E1 activity before and after chronic ethanol and/or nicotine exposure. CYP2E1 protein levels and in vitro chlorzoxazone metabolism were assessed in liver microsomes. Average daily ethanol consumption was ≈3.0 g/kg (blood ethanol levels ≈24 mM) and was unaffected by nicotine treatment. Ethanol self-administration and nicotine treatment, alone and in combination, significantly increased in vivo CZN disposition compared with that in control animals. The effect of ethanol was only observed at higher levels of intake. Ethanol and nicotine increased CYP2E1 protein levels and in vitro CZN metabolism, with combined exposure to both drugs resulting in the greatest increase. The effect of ethanol was also dependent on level of intake. Chronic exposure to ethanol and nicotine induced hepatic CYP2E1 activity and protein levels, particularly when both drugs were used in combination and when ethanol intake was high. These results have important implications for public health, given the association between elevated CYP2E1 and disease, and the large proportion of individuals who are exposed to ethanol and nicotine, often in combination.

Alcohol drinking and colorectal cancer risk: an overall and dose-response meta-analysis of published studies

BACKGROUND

The International Agency for Research on Cancer (IARC) concluded that alcohol consumption is related to colorectal cancer (CRC). However, several issues remain unresolved, including quantification of the association for light (≤1 drink/day) and moderate (2-3 drinks/day) alcohol drinking, investigation of the dose-response relationship, and potential heterogeneity of effects by sex, colorectal site, and geographical region.

METHODS

Twenty-seven cohort and 34 case-control studies presenting results for at least three categories of alcohol intake were identified from a PubMed search of articles published before May 2010. The summary relative risks (RRs) were estimated by the random effects model. Second-order fractional polynomials and random effects meta-regression models were used for modeling the dose-risk relation.

RESULTS

The RRs were 1.21 [95% confidence interval (CI) 1.13-1.28] for moderate and 1.52 (95% CI 1.27-1.81) for heavy (≥4 drinks/day) alcohol drinking. The RR for moderate drinkers, compared with non-/occasional drinkers, was stronger for men (RR = 1.24, 95% CI 1.13-1.37) than for women (RR = 1.08, 95% CI 1.03-1.13; P(heterogeneity) = 0.02). For heavy drinkers, the association was stronger in Asian studies (RR = 1.81, 95% CI 1.33-2.46; P(heterogeneity) = 0.04). The dose-risk analysis estimated RRs of 1.07 (95% CI 1.04-1.10), 1.38 (95% CI 1.28-1.50), and 1.82 (95% CI 1.41-2.35) for 10, 50, and 100 g/day of alcohol, respectively.

CONCLUSIONS

This meta-analysis provides strong evidence for an association between alcohol drinking of >1 drink/day and colorectal cancer risk.

The impact of CYP2E1 genetic variability on risk assessment of VOC mixtures

Humans are simultaneously exposed to multiple chemicals in the environment. Many of the chemicals use the same enzymes in their metabolic pathways. Competitive inhibition may occur as one of the possible interactions between the xenobiotics in human body. For example, many volatile organic compounds (VOCs) are metabolized using P450 enzymes, specifically CYP2E1. Inheritable gene alterations may result in changes of function of the enzymes in different human subpopulations. Variations in quantity and/or quality of particular isoenzymes may cause differences in the metabolism of VOCs. These variations may cause higher sensitivity in certain populations. Using examples of three different mixtures, this review paper outlines the variances in CYP2E1 isoenzymes, effect of exposure to such mixtures on sensitive populations, and approaches to mixtures risk assessment.

CYP2E1 PstI/RsaI polymorphism and colorectal cancer risk: A meta-analysis

AIM: To clarify the association between CYP2E1 PstI/RsaI polymorphism and susceptibility to colorectal cancer.

METHODS: A meta-analysis based on 10 eligible case-control studies involving 4979 cases and 6012 controls was carried out to summarize the data on the association between CYP2E1 RsaI/PstI polymorphism and colorectal cancer risk.

RESULTS: In comparison of the homozygote c2c2 and c2 carriers (c1c2 + c2c2) and the homozygous wild-type genotype (c1c1), no association was found between CYP2E1 RsaI/PstI polymorphism and colorectal cancer risk [odds ratio (OR) = 1.24 (95% CI: 0.93-1.66) for c2c2; OR = 1.02 (95% CI: 0.88-1.19) for c2 carriers]. In stratified analysis, Caucasians with c2c2 homozygote appeared to have an increased risk of colorectal cancer (OR = 2.67, 95% CI: 1.03-6.89, P = 0.043), no significant associations were found in other groups.

CONCLUSION: c2c2 homozygote of CYP2E1 PstI/RsaI polymorphism may be associated with the increased risk of colorectal cancer in Caucasians, which needs further investigations.

A novel polymorphism rs1329149 of CYP2E1 and a known polymorphism rs671 of ALDH2 of alcohol metabolizing enzymes are associated with colorectal cancer in a southwestern Chinese population

BACKGROUND

To screen for tagging single nucleotide polymorphisms (tagSNP) in the major alcohol metabolizing enzymes: ADH1B, ALDH2, and CYP2E1, and to evaluate the association between these tagSNPs and colorectal cancer (CRC) in a southwestern Chinese population.

METHODS

A hospital-based case-control study of 440 CRC patients and 800 cancer-free controls was conducted. Personal information was collected by a Semi-Quantitative Food Frequency Questionnaire. The tagSNPs were screened in the HapMap with Haploview by setting the minor allele frequency at 0.03 with the highest score of r(2) form each block. Genotypes were identified by using the SNPLex System. Both crude and adjusted odds ratio (OR) and 95% confidence interval (CI) were used to evaluate the risk of each SNP.

RESULTS

Sixteen tagSNPs were selected, and 13 were successfully genotyped. A novel CYP2E1 locus rs1329149 and a known ALDH2 locus rs671 were found to be significantly associated with CRC risk. The adjusted OR was 1.86 (95% CI, 1.12-3.09) for the rs671 A/A genotype and 4.04 for the rs1329149 T/T genotype (95% CI, 2.44-6.70), compared with their common homozygous genotypes. Interaction was found between alcohol consumption and gene polymorphisms on CRC, the adjusted OR was 7.17 (95% CI, 2.01-25.53) for drinking habits combined with rs671 A/A or rs1329149 T/T genotype.

CONCLUSION

The results of this study suggest that rs671 A/A and the first reported locus rs1329149 T/T genotypes increase the susceptibility to CRC, and gene-environmental interaction between the two loci and alcohol use existed for CRC in Southwestern Chinese. Larger studies are warranted to verify our findings.