Cervical cancer and CYP2E1 polymorphisms: implications for molecular epidemiology

Introduction Besides human papillomavirus (HPV) infection, several cofactors are considered important for the development of cervical cancer (CC). Among these, tobacco smoke, other sexually transmitted diseases, inflammation and nutritional factors have been intensively described. CYP2E1 polymorphisms have been associated with the metabolization of several carcinogens, some of them considered risk factors for CC development, such as tobacco smoke. The aim of this study was to evaluate the role of CYP2E1 polymorphisms in the susceptibility to cervical cancer in a Portuguese population. Patients and methods The genotypic analysis was performed with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology, using peripheral blood samples of 454 individuals: 122 presented invasive squamous cell carcinoma (ICC), 59 presented squamous intraepithelial lesions (SIL), and the control population was composed of 274 healthy individuals. Results Concerning the DraI polymorphism, we observed a decreased risk for the development of squamous cervical lesions in the presence of the C allele [odds ratio (OR)=0.600; 0.378<OR<0.952; p=0.029]. In the stratification of the analysis according to the mean age, we observed an increased risk for the development of SIL, for women older than 39 years of age, in the presence of the D allele (OR=0.087; 0.012<OR<0.651; p=0.003). Regarding the RsaI polymorphism, we did not find any significant differences. Conclusion The decreased risk observed for the development of SIL and not ICC in the presence of the D allele may indicate that CYP2E1 interferes with the initial steps of the carcinogenic process, probably due to its involvement in the action of immunological mediators, expressed during cervical inflammation. These aspects may help to define new therapeutic strategies for chemoprevention.     

Role of CYP1A2 and CYP2E1 in the pentoxifylline ciprofloxacin drug interaction

In this study the drug interaction between ciprofloxacin (CIPRO) and pentoxifylline (PTX) was investigated and the role of CYP1A2 in the drug interaction was determined with the aid of a selective CYP1A2 inhibitor, furafylline (FURA), and the Cyp1A2 knockout mouse. Serum concentrations of PTX (83.4+/-1 micromol/l) and metabolite-1 (M-1) (13.7+/-2.8 micromol/l) following a single injection of PTX (100 mg/kg i.p.) were significantly higher (P<0.05) in mice treated with CIPRO (25 mg/kg i.p. 9 days) compared to serum concentrations of PTX (46.3+/-0.5 micromol/l) and M-1 (6.4+/-1.1 micromol/l) in mice administered saline. Murine hepatic microsomes were incubated with PTX alone or the combination of PTX and CIPRO. The metabolism of PTX in the murine hepatic microsomes containing both CIPRO and PTX was significantly decreased compared to microsomes incubated with PTX alone, suggesting that CIPRO may inhibit the metabolism of PTX. To further clarify the role of CYP1A2 in the metabolism of PTX in mice, the effect of a selective CYP1A2 mechanism based inhibitor, FURA, on the metabolism of PTX was investigated and our results indicate that FURA inhibited metabolism of PTX. We then investigated PTX elimination in the Cyp1A2 knockout mouse. Blood levels of PTX were assessed at 2 and 20 min following a single injection of PTX (32 mg/kg i.v). Serum concentration of PTX was determined in Cyp1A2 knockout mice compared to Cyp1A2 wild type control mice. The serum concentration of PTX in Cyp1A2 wild type mice (n=9) was 22.2+/-3.2 micromol/l at 20 min following injection of PTX. The serum concentration of PTX in Cyp1A2 knockout mice (n=11) was significantly elevated at 20 min following injection of PTX compared to Cyp1A2 wild type mice. These results clearly indicate that inhibition of CYP1A2 catalytic activity that occurs in the Cyp1A2 knockout mice is sufficient to alter metabolism of PTX and result in markedly elevated levels in serum of Cyp1A2 knockout mice. The results of Western analysis in murine microsomes suggest that CYP1A2 protein levels were not altered by CIPRO indicating that CIPRO did not downregulate Cyp1A2. The results of Western analysis also indicated that CIPRO treatment increased CYP2E1 in mouse microsomes and the implications of these will be discussed.     

Role of CYP2E1 in deramciclane metabolism.

The aim of our study was to identify the form(s) of cytochrome P450 responsible for the metabolism of deramciclane, a new anxiolytic drug candidate. The main routes of biotransformation in hepatic microsomes were side chain modification (N-demethylation or total side chain cleavage) and hydroxylation at several points of the molecule. Although several cytochrome P450 forms were involved in the metabolism, the role of CYP2E1 should be emphasized, since it catalyzed almost all steps. Production of deramciclane metabolites was significantly inhibited by diethyl-dithiocarbamate and was elevated in liver microsomes of isoniazid-treated rats. Furthermore, cDNA-expressed rat CYP2E1 generated the metabolites formed by side chain modification and hydroxylation. Neither deramciclane nor its primary metabolite, N-desmethyl deramciclane were able to influence directly the activity of CYP2E1. However, during the biotransformation, one or more metabolites must have been formed which were potent inhibitors of CYP2E1.     

Role of CYP2E1 in thioacetamide-induced mouse hepatotoxicity

Previous experiments showed that treatment of mice and rats with thioacetamide (TAA) induced liver cell damage, fibrosis and/or cirrhosis, associated with increased oxidative stress and activation of hepatic stellate cells. Some experiments suggest that CYP2E1 may be involved in the metabolic activation of TAA. However, there is no direct evidence on the role of CYP2E1 in TAA-mediated hepatotoxicity. To clarify this, TAA-induced hepatotoxicity was investigated using Cyp2e1-null mice. Male wild-type and Cyp2e1-null mice were treated with TAA (200 mg/kg of body weight, single, i.p.) at 6 weeks of age, and hepatotoxicity examined 24 and 48 h after TAA treatment. Relative liver weights of Cyp2e1-null mice were significantly different at 24 h compared to wild-type mice (p<0.01). Serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) in Cyp2e1-null mice were significantly different at both time points compared to wild-type mice (p<0.01). Histopathological examination showed Cyp2e1-null mice represented no hepatototoxic lesions, in clear contrast to severe centriobular necrosis, inflammation and hemorrhage at both time points in wild-type mice. Marked lipid peroxidation was also only limited to wild-type mice (p<0.01). Similarly, TNF-alpha, IL-6 and glutathione peroxidase mRNA expression in Cyp2e1-null mice did not significantly differ from the control levels, contrasting with the marked alteration in wild-type mice (p<0.01). Western blot analysis further revealed no increase in iNOS expression in Cyp2e1-null mice. These results reveal that CYP2E1 mediates TAA-induced hepatotoxicity in wild-type mice as a result of increased oxidative stress.     

Cytochrome P450 CYP1B1 and catechol O-methyltransferase (COMT) genetic polymorphisms and breast cancer susceptibility in a Turkish population

Epidemiological studies indicate that most risk factors for breast cancer are related to reproductive and hormonal factors. Estrogen has been proposed to trigger breast cancer development via an initiating mechanism involving its metabolite, catechol estrogen (CE). Because of the important role of cytochrome P450 1B1 ( CYP1B1) and catechol O-methyltransferase ( COMT) in mammary estrogen and carcinogen metabolism, we examined the CYP1B1 and COMT genes to determine whether genetic variations could account for inter-individual differences in breast cancer. In this case-control study, we determined CYP1B1 and COMT genotypes in 84 breast cancer patients and 103 healthy unrelated women controls from a Turkish population. In the case of CYP1B1, we genotyped CYP1B1*3 (L432 V) allele. We found that carriers of the CYP1B1*3 allele were more frequent among breast cancer patients with adjusted odds ratio (OR) for age, age at menarche, age at first full-term pregnancy, body mass index (BMI) and smoking status of 2.32 (95% confidence interval 1.26-4.25) associated with the allele. However, this allele appeared to be a significant factor for susceptibility only in patients with a BMI greater than 24 kg/m(2). Menopausal status did not appear to affect susceptibility. In the case of COMT, there was no significant difference in susceptibility for breast cancer development between patients with low activity COMT-L (V158 M) allele and high activity COMT-H allele, and susceptibility was not affected by menopausal status, BMI or CYP1B1 genotype. We conclude that the CYP1B1* 3 allele appears to be a factor for susceptibility to breast cancer in Turkish women especially those with a BMI greater than 24 kg/m(2).     

Ethnic differences in genetic polymorphisms of CYP2D6, CYP2C19, CYP3As and MDR1/ABCB1

Metabolic capacities for debrisoquin, sparteine, mephenytoin, nifedipine, and midazolam, which are substrates of polymorphic CYP2D6, CYP2C19, and CYP3A, have been reported to exhibit, in many cases, remarkable interindividual and ethnic differences. These ethnic differences are partly associated with genetic differences. In the case of the drug transporter ABCB1/MDR1, interindividual differences in its transporter activities toward various clinical drugs are also attributed to several ABCB1/MDR1 genetic polymorphisms. In this review, the existence and frequency of various low-activity alleles of drug metabolizing enzymes as well as populational drug metabolic capacities are compared among several different races or ethnicities. Distribution of nonsynonymous ABCB1/MDR1 SNPs and haplotype frequency in various races are summarized, with the association of nonsynonymous SNPs with large functional alterations as a rare event.     

Pharmacokinetics of paclitaxel in ovarian cancer patients and genetic polymorphisms of CYP2C8, CYP3A4, and MDR1

Interindividual differences in the pharmacokinetics of paclitaxel and its metabolites in Japanese ovarian cancer patients were investigated in relation to genetic polymorphisms of the CYP2C8, CYP3A4, and MDR1 genes. The area under the concentration-time curve (AUC) ratios of paclitaxel/6alpha-hydroxypaclitaxel and paclitaxel/3 -p-hydroxypaclitaxel calculated as the metabolic index of CYP2C8 and CYP3A4 showed 13- and 12-fold interindividual variations, respectively. No patient had any CYP2C8 variants, while 2 patients were heterozygotes of CYP3A4*16. For the MDR1 gene, the frequencies of -129C, 1236C, 2677T, 2677A, and 3435T alleles were 2.2%, 8.7%, 56.5%, 4.4%, and 52.2%, respectively. Subjects possessing the 3435T allele had a significantly (P < .05) higher AUC of 3'- p-hydroxypaclitaxel compared to those possessing the 3435C allele. Leukocytopenia was significantly (P < .05) related to the AUC of paclitaxel. Genotyping of the CYP2C8, CYP3A4, and MDR1 genes might not be essential to predict adverse effects of paclitaxel in Japanese patients, although an allelic variant of MDR1 may functionally affect the pharmacokinetics of its metabolite.     

Effects of genetic polymorphisms of CYP1A1, CYP2E1, GSTM1, and GSTT1 on the urinary levels of 1-hydroxypyrene and 2-naphthol in aircraft maintenance workers

This study was undertaken to investigate the effects of genetic polymorphisms of the cytochrome P450 1A1 (CYP1A1) and 2E1 (CYP2E1), and glutathione S-transferases mu (GSTM1) and theta (GSTT1) on urinary 1-hydroxypyrene and 2-naphthol levels, and to estimate the level of exposure to polycyclic aromatic hydrocarbons (PAHs) in aircraft maintenance workers. In 218 Korean aircraft maintenance workers, the geometric means of urinary 1-hydroxypyrene and 2-naphthol were 0.32 and 3.25 micromol/mol creatinine, respectively. These urinary concentrations were approximately at the upper limit of the general population. Mean urinary 2-naphthol concentrations were significantly different between smokers and non-smokers. CYP1A1 and GSTM1 were statistically significant in analyses on both 1-hydroxypyrene and 2-naphthol levels among smokers. The results suggest that smoking has more profound effects on urinary PAH metabolites than does genetic polymorphisms in this population, and that CYP1A1 and GSTM1 activity might be related to the metabolism of 1-hydroxypyrene and 2-naphthol.     

Association of CYP2E1, GST and mEH genetic polymorphisms with urinary acrylamide metabolites in workers exposed to acrylamide

This study elucidates the association of acrylamide metabolites, N-acetyl-S-(2-carbamoylethyl)-cysteine (AAMA), N-acetyl-S-(1-carbamoyl-2-hydroxyethyl)-cysteine (GAMA2), and N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-cysteine (GAMA3) in urine with genetic polymorphisms of the metabolic enzymes cytochrome P450 2E1 (CYP2E1), microsomal epoxide hydrolase (mEH) in exon 3 and exon 4, glutathione transferase theta (GSTT1) and mu (GSTM1), involved in the activation and detoxification of acrylamide (AA) in humans. Eighty-five workers were recruited, including 51 AA-exposed workers and 34 administrative staffs serve as controls. Personal air sampling was performed for the exposed workers. Each subject provided pre- and post-shift urine samples and blood samples. Urinary AAMA, GAMA2 and GAMA3 levels were simultaneously quantified using liquid chromatography-electronspray ionization/tandem mass spectrometry (LC-ESI-MS/MS). CYP2E1, mEH (in exon 3 and exon 4), GSTT1, and GSTM1 were analyzed using polymerase chain reaction (PCR). Our results reveal that AA personal exposures ranged from 4.37 × 10⁻³ to 113.61 μg/m³ with a mean at 15.36 μg/m³. The AAMA, GAMA2, and GAMA3 levels in the exposed group significantly exceeded those in controls. The GAMAs (the sum of GAMA2 and GAMA3)/AAMA ratios, potentially reflecting the proportion of AA metabolized to glycidamide (GA), varied from 0.003 to 0.456, and indicate high inter-individual variability in the metabolism of AA to GA in this study population. Multivariate regression analysis demonstrates that GSTM1 genotypes significantly modify the excretion of urinary AAMA and the GAMAs/AAMA ratio, exon 4 of mEH was significantly associated with the urinary GAMAs levels after adjustment for AA exposures. These results suggest that mEH and/or GSTM1 may be associated with the formation of urinary AAMA and GAMAs. Further study may be needed to shed light on the role of both enzymes in AA metabolism.     

GSTM家族基因多态性与乳腺癌遗传易感性

乳腺癌是复杂性多基因疾病.低外显率基因谷胱甘肽-S-转移酶(GST)基因在乳腺癌遗传易感性中的作用逐渐受到重视.GST基因家族成员之一的GSTM基因的多态性与某些癌症的发生相关联,尽管GSTM基因多态性与乳腺癌遗传易感性的研究尚未获得一致的结论,但相关研究及其进展值得关注.     

Influence of polymorphisms of drug metabolizing enzymes (CYP2B6, CYP2C9, CYP2C19, CYP3A4, CYP3A5, GSTA1, GSTP1, ALDH1A1 and ALDH3A1) on the pharmacokinetics of cyclophosphamide and 4-hydroxycyclophosphamide

PURPOSE: The anticancer agent, cyclophosphamide, is metabolized by cytochrome P450 (CYP), glutathione S-transferase (GST) and aldehyde dehydrogenase (ALDH) enzymes. Polymorphisms of these enzymes may affect the pharmacokinetics of cyclophosphamide and thereby its toxicity and efficacy. The purpose of this study was to evaluate the effects of known allelic variants in the CYP2B6, CYP2C9, CYP2C19, CYP3A4, CYP3A5, GSTA1, GSTP1, ALDH1A1 and ALDH3A1 genes on the pharmacokinetics of the anticancer agent, cyclophosphamide, and its active metabolite 4-hydroxycyclophosphamide. EXPERIMENTAL DESIGN: A cohort of 124 Caucasian patients received a high-dose chemotherapy combination consisting of cyclophosphamide (4-6 g/m2), thiotepa (320-480 mg/m2) and carboplatin (area under the curve 13-20 mg x min/ml) as intravenous infusions over 4 consecutive days. Genomic DNA was analysed using PCR and sequencing. Liquid chromatography-tandem mass spectrometry was used to measure plasma concentrations of cyclophosphamide and 4-hydroxycyclophosphamide. The relationship between allelic variants and the elimination pharmacokinetic parameters noninducible cyclophosphamide clearance (CL(nonind)), inducible cyclophosphamide clearance (CL(ind)) and elimination rate constant of 4-hydroxycyclophosphamide (k(4OHCP)) were evaluated using nonlinear mixed effects modelling. RESULTS: The interindividual variability in the noninducible cyclophosphamide clearance, inducible cyclophosphamide clearance and 4-hydroxycyclophosphamide clearance was 23, 27 and 31%, respectively. No effect of the allelic variants investigated on the clearance of cyclophosphamide or 4-hydroxycyclophosphamide could be demonstrated. CONCLUSION: This study indicates that the presently evaluated variant alleles in the CYP2B6, CYP2C9, CYP2C19, CYP3A4, CYP3A5, GSTA1, GSTP1, ALDH1A1 and ALDH3A1 genes do not explain the interindividual variability in cyclophosphamide and 4-hydroxycyclophosphamide pharmacokinetics and are, probably, not the cause of the observed variability in toxicity.     

CYP1A1 and GSTM1 genetic polymorphisms in lung cancer populations exposed to arsenic in drinking water

Region II of Chile is the most important copper mining area in the world and it shows the highest lung cancer mortality rate in the country (35/100,000). The population in Antofagasta, the main city of Region II, was exposed from 1958 to 1970 to 860 microg m(-3) arsenic (As) in drinking water and has currently been declining to 40 microg m(-3). Glutathione serves as a reducing agent and glutathione S-transferase (GST) may have an important role in As methylation capacity and body retention. In the current study, the null genotype of GSTM1 and the MspI polymorphism of CYP450 1A1 were investigated in lung cancer patients and in healthy volunteers of Region II. In males, the 2A genotype of MspI represented a highly significant estimated relative lung cancer risk (OR=2.60). Relative lung cancer risk for the combined 2A/null GSTM1 genotypes was 2.51, which increased with the smoking habit (OR=2.98). In Region II, the cancer mortality rate for As-associated cancers at least partly might be related to differences in As biotransformation. Genetic biomarkers such as 2A and GSTM1 polymorphisms in addition to DR70 as screening biomarkers might provide relevant information to identify individuals with a high risk for lung cancer as prevention and protection actions to protect public health.     

Association of CYP1B1 genetic polymorphism with incidence to breast and lung cancer

Cytochrome P450 1B1 (CYP1B1) participates in the metabolic activation of a number of procarcinogens including benzo[a]pyrene and the hydroxylation of 17beta-estradiol at the C-4 position. In this study, we investigated the association between CYP1B1 genetic polymorphism and breast or lung cancer incidence. The Ala-Ser polymorphism at codon 119 in presumed substrate recognition site 1 was significantly associated with the incidence of breast or squamous cell carcinoma of the lung. On the other hand, Leu-Val polymorphism at codon 432 did not show any association to the cancers. An allele containing both Ala and Leu simultaneously, comprised 75% of alleles among 315 Japanese healthy controls, was significantly inversely associated with breast cancer incidence. When expressed in a recombinant system, this CYP1B1 cDNA showed the lowest 17beta-estradiol 4-hydroxylase activity among four different variant forms of CYP1B1. Thus, inter-individual differences in activation of procarcinogens or metabolism of oestrogen originating from genetic polymorphisms of the human CYP1B1 gene may contribute to the susceptibility of human cancers.     

CYP1A1 and GSTM1 genetic polymorphisms in lung cancer populations exposed to arsenic in drinking water

Region II of Chile is the most important copper mining area in the world and it shows the highest lung cancer mortality rate in the country (35/100?000). The population in Antofagasta, the main city of Region II, was exposed from 1958 to 1970 to 860?µg?m^?3 arsenic (As) in drinking water and has currently been declining to 40?µg?m^?3. Glutathione serves as a reducing agent and glutathione S-transferase (GST) may have an important role in As methylation capacity and body retention. In the current study, the null genotype of GSTM1 and the MspI polymorphism of CYP450 1A1 were investigated in lung cancer patients and in healthy volunteers of Region II. In males, the 2A genotype of MspI represented a highly significant estimated relative lung cancer risk (OR?=?2.60). Relative lung cancer risk for the combined 2A/null GSTM1 genotypes was 2.51, which increased with the smoking habit (OR?=?2.98). In Region II, the cancer mortality rate for As-associated cancers at least partly might be related to differences in As biotransformation. Genetic biomarkers such as 2A and GSTM1 polymorphisms in addition to DR70 as screening biomarkers might provide relevant information to identify individuals with a high risk for lung cancer as prevention and protection actions to protect public health.     

Role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to organophosphate pesticides

Organophosphate pesticides (OPs) are primarily metabolized by several xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticide-exposed workers. The present study was designed to determine the role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to OPs. We examined 284 subjects including 150 workers occupationally exposed to OPs and 134 normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using PCR-RFLP. The results revealed that the PONase activity toward paraoxonase and AChE activity was found significantly lowered in workers as compared to control subjects (p < 0.001). Workers showed significantly higher DNA damage compared to control subjects (14.37 ± 2.15 vs. 6.24 ± 1.37 tail% DNA, p < 0.001). Further, the workers with CYP2D6*3 PM and PON1 (QQ and MM) genotypes were found to have significantly higher DNA damage when compared to other genotypes (p < 0.05). In addition, significant increase in DNA damage was also observed in workers with concomitant presence of certain CYP2D6 and PON1 (Q192R and L55M) genotypes which need further extensive studies. In conclusion, the results indicate that the PON1 and CYP2D6 genotypes can modulate DNA damage elicited by some OPs possibly through gene-environment interactions.     

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 in ketone-stimulated insulin release in pancreatic B-cells

The role of CYP2E1 in ketone-stimulated insulin release was investigated using isolated pancreatic islets of Langerhans and two mammalian insulin secreting pancreatic beta-cell lines engineered to stably express human CYP2E1 (designated BRIN BD11h2E1 and INS-1h2E1). Isolated rat pancreatic islets were shown to express the CYP2E1 isoform which was inducible by pretreatment of animals with acetone. The cDNA encoded CYP2E1 was expressed and inducible in the engineered cells as shown by Western blotting. The transfected protein was enzymatically active in the heterologous cells as determined by p-nitrophenol hydroxylation rates (0.176 +/- 0.08 vs. 0.341 +/- 0.08 nmol/min/mg microsomal protein in BRIN BD11 control cells and BRIN BD11h2E1 cells respectively, P < 0.001; 0.204 +/- 0.03 vs. 0.633 +/- 0.102 nmol/min/mg microsomal protein in INS-1 and INS-1h2E1, respectively, P < 0.001). Cultivation of CYP2E1 expressing BRIN BD11h2E1 and INS-1h2E1 cells in 40 mM ethanol increased the rate of p-nitrophenol hydroxylation (0.968 +/- 0.09 nmol/min/mg microsomal protein, P < 0.001 and 0.846 +/- 0.103 nmol/min/mg microsomal protein, P < 0.001, respectively) providing further evidence that the heterologous protein is inducible. Cultivation of control cells with ethanol had no observable effect (0.186 +/- 0.05 and 0.195 +/- 0.03 in BRIN BD11 and INS-1, respectively). These cell lines also express NADPH-cytochrome P450 reductase protein which was enzymatically active (0.632 +/- 0.023 in parental BRIN BD11 vs. 0.657 +/- 0.066 without ethanol and 0.824 +/- 0.014 nmol/min/mg microsomal protein with ethanol in BRIN BD11h2E1, P < 0.05; and 1.568 +/- 0.118 in parental INS-1 vs. 1.607 +/- 0.093 without ethanol and 1.805 +/- 0.066 nmol/min/mg microsomal protein with ethanol in INS-1h2E1, P < 0.05) thereby providing a functional cytochrome P450 system. The insulin secretory response of control cell lines and islets was similar to cell lines and islets which had been chemically pretreated, to induce CYP2E1 expression, in response to known nutrient secretagogues. However, insulin output was significantly higher in pretreated islets (1.3-fold, P < 0.05) and CYP2E1 expressing cell lines (BRIN BD11h2E1 2.3-fold, P < 0.001; INS1-1h2E1 1.6-fold, P < 0.001) when stimulated with the ketone 3-hydroxybutyrate than control islets and parental cell lines respectively. Similar acute exposure to acetoacetate enhanced insulin secretion by 1.3-fold (P < 0.05) in pretreated islets, 2.6-fold (P < 0.001) in ethanol pretreated BRIN BD11h2E1 and 1.4-fold (P < 0.001) in ethanol pretreated INS-1h2E1 cells compared to the respective control islets or ethanol pretreated control parental cells. Therefore, these studies highlight a possible role for CYP2E1 in pancreatic cell dysfunction.     

CYP2 E1在酒精性肝病中的作用

酒精性肝病(ALD)是一种长期大量饮酒所致的慢性肝脏疾病。乙醇经肝脏代谢产生大量的自由基和活性氧。氧化应激在乙醇引起肝损伤的机制发挥关键作用。在肝脏,细胞色素P450 2E1(CYP2E1)可被乙醇诱导并参与乙醇代谢,CYP2E1是一种有效的活性氧产生酶,产生超氧阴离子自由基和过氧化氢,铁催化剂的存在下,产生羟基自由基。该文主要总结了CYP2E1在ALD发病过程中的作用及机制,为ALD的临床治疗提供思路。