CYP enzyme polymorphisms and susceptibility to HCV-related chronic liver disease and liver cancer

Impact of liver fibrosis and clinical characteristics on dose-adjusted serum methadone concentrations

BACKGROUND

There is limited knowledge on the causes of large variations in serum methadone concentrations and dose requirements.

OBJECTIVES

We investigated the impact of the degree of liver fibrosis on dose-adjusted steady-state serum methadone concentrations.

METHODS

We assessed the clinical and laboratory data of 155 Norwegian patients with opioid use disorder undergoing methadone maintenance treatment in outpatient clinics in the period 2016-2020. A possible association between the degree of liver fibrosis and dose-adjusted serum methadone concentration was explored using a linear mixed-model analysis.

RESULTS

When adjusted for age, gender, body mass index, and genotypes of CYP2B6 and CYP3A5, the concentration-to-dose ratio of methadone did not increase among the participants with liver fibrosis (Coefficient: 0.70; 95% CI: -2.16, 3.57; P: 0.631), even among those with advanced cirrhosis (-0.50; -4.59, 3.59; 0.810).

CONCLUSIONS

Although no correlation was found between the degree of liver stiffness and dose-adjusted serum methadone concentration, close clinical monitoring should be considered, especially among patients with advanced cirrhosis. Still, serum methadone measurements can be considered a supplement to clinical assessments, taking into account intra-individual variations.

CYP1B1: A Novel Molecular Biomarker Predicts Molecular Subtype, Tumor Microenvironment, and Immune Response in 33 Cancers

BACKGROUND

Cytochrome P450 Family 1 Subfamily B Member 1 (CYP1B1) is a critical metabolic enzyme of melatonin. Although melatonin has been identified to exhibit tumor suppressing activity, the role and mechanism of the clinical and immunological characteristics of CYP1B1 in cancer remain unclear.

METHODS

In this study, RNA expression and clinical data were obtained from The Cancer Genome Atlas (TCGA) across 33 solid tumors. The expression, survival, immune subtype, molecular subtype, tumor mutation burden (TMB), microsatellite instability (MSI), biological pathways, and function in vitro and vivo were evaluated. The predictive value of CYP1B1 in immune cohorts was further explored.

RESULTS

We found the dysregulated expression of CYP1B1 was associated with the clinical stage and tumor grade. Immunological correlation analysis showed CYP1B1 was positively correlated with the infiltration of lymphocyte, immunomodulator, chemokine, receptor, and cancer-associated fibroblasts (CAFs) in most cancer. Meanwhile, CYP1B1 was involved in immune subtype and molecular subtype, and was connected with TMB, MSI, neoantigen, the activation of multiple melatonergic and immune-related pathways, and therapeutic resistance.

CONCLUSIONS

Together, this study comprehensively revealed the role and mechanism of CYP1B1 and explored the significant association between CYP1B1 expression and immune activity. These findings provide a promising predictor and molecular target for clinical immune treatment.

β-Carotene Increases Activity of Cytochrome P450 2E1 during Ethanol Consumption

One of the key routes through which ethanol induces oxidative stress appears to be the activation of cytochrome P450 2E1 at different levels of ethanol intake. Our aim was to determine if oral β-carotene intake had an antioxidant effect on CYP2E1 gene expression in mice that had previously consumed ethanol. C57BL/6 mice were used and distributed into: control (C), low-dose alcohol (LA), moderate-dose alcohol (MA), β-carotene (B), low-dose alcohol+β-carotene (LA + B), and moderate-dose alcohol+β-carotene (MA + B). Animals were euthanized at the end of the experiment, and liver tissue was taken from each one. CYP2E1 was measured using qPCR to detect liver damage. The relative expression level of each RNA was estimated using the comparative threshold cycle (Ct) technique (2^−ΔΔCT method) by averaging the Ct values from three replicates. The LA+B (2267 ± 0.707) and MA+B (2.307 ± 0.384) groups had the highest CYP2E1 fold change values. On the other hand, the C (1.053 ± 0.292) and LA (1.240 ± 0.163) groups had the lowest levels. These results suggest that ethanol feeding produced a fold increase in CYP2E1 protein in mice as compared to the control group. Increased CYP2E1 activity was found to support the hypothesis that β-carotene might be dangerous during ethanol exposure in animal models. Our findings imply that β-carotene can increase the hepatic damage caused by low and high doses of alcohol. Therefore, the quantity of alcohol ingested, the exposure period, the regulatory mechanisms of alcoholic liver damage, and the signaling pathways involved in the consumption of both alcohol and antioxidant must all be considered.

Use of proteomics to identify mechanisms of hepatocellular carcinoma with the CYP2D6*10 polymorphism and identification of ANGPTL6 as a new diagnostic and prognostic biomarker

BACKGROUND

Although an association between the cytochrome P4502D6 (CYP2D6) *10 (100C>T) polymorphism and hepatocellular carcinoma (HCC) is known, the mechanism remains unclear. Here we aimed to explore mechanisms of CYP2D6*10 (100C>T) polymorphism conferring to HCC, and screen markers for HCC.

METHODS

Label-free global proteome profiling with 34 normal livers and peritumor tissue from 61 HCC patients was performed, and angiopoietin-like protein-6 (ANGPTL6) was evaluated in 2 liver samples validation cohorts and 2 blood specimens validation cohorts.

RESULTS

We found a significantly decreased frequency of TT in HCC patients which reduced HCC susceptibility by 69.2% and was accompanied by lowered enzymatic activity for CYP2D6. Proteomic analysis revealed 1342 differentially expressed proteins (DEPs) that were associated with HCC and 88 DEPs were identified as 100 TT-related proteins, likely underlying the susceptibility to HCC. Twenty-two upregulated DEPs and 66 downregulated DEPs were mainly related to lipid metabolism and the extracellular matrix, respectively. High ANGPTL6 was associated with a higher risk to HCC and worse prognosis. ANGPTL6 was both an independent risk factor and an independent prognostic factor for HCC and exhibited strong potential for predicting HCC occurrence, with comparable AUC values and higher sensitivity compared with alpha-fetoprotein.

CONCLUSIONS

The TT genotype-associated decreased risk of HCC appears to be related to lowered CYP2D6 activity and altered protein expression in the tumor microenvironment, and ANGPTL6 is a promising new diagnostic and prognostic biomarker for HCC. Our findings reveal new mechanistic insights for polymorphisms related to HCC risk and provide avenues for screening for HCC.

Elucidation of the Mechanisms and Molecular Targets of Shuanglian Decoction for the Treatment of Hepatocellular Carcinoma Based on Network Pharmacology

Shuanglian decoction (SLD) is traditionally used to treat hepatocellular carcinoma (HCC) in the clinical practice of traditional Chinese medicine. However, its mechanisms of action and molecular targets for the treatment of HCC are not clear. The active compounds of SLD were collected and their targets were identified. HCC-related targets were obtained by analyzing the differentially expressed genes between HCC patients and healthy individuals. Protein-protein interaction (PPI) data were then obtained and PPI networks of SLD putative targets and HCC-related targets were visualized and merged to identify the candidate targets for SLD against HCC. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis were carried out. The gene-pathway network was constructed to screen the key target genes. In total, 35 active compounds and 31 targets of SLD were identified. In total, 245 differentially expressed genes with P values <0.005 and |log2 (fold change)| > 1 were identified between HCC patients and control groups, and 68 target genes associated with HCC were finally identified. Twenty-one pathways including cellular senescence, p53 signaling pathway, and cell cycle were significantly enriched. CYP3A4 was the core gene and other several genes including CYP1A2, PPP3CA, PTGS2, CCCNB1, and CDK1 were the key genes in the gene-pathway network of SLD for the treatment of HCC. The results indicated that SLD's effects against HCC may relate to the regulation of an antioxidant function through specific biological processes and related pathways. This study demonstrates the application of network pharmacology in evaluating mechanisms of action and molecular targets of complex herbal formulations.

Multi-factorial pharmacokinetic interactions: unraveling complexities in precision drug therapy

Introduction: Precision drug therapy requires accounting for pertinent factors in pharmacokinetic (PK) inter-individual variability (i.e., pharmacogenetics, diseases, polypharmacy, and natural product use) that can cause sub-therapeutic or adverse effects. Although each of these individual factors can alter victim drug PK, multi-factorial interactions can cause additive, synergistic, or opposing effects. Determining the magnitude and direction of these complex multi-factorial effects requires understanding the rate-limiting redundant and/or sequential PK processes for each drug.Areas covered: Perturbations in drug-metabolizing enzymes and/or transporters are integral to single- and multi-factorial PK interactions. Examples of single factor PK interactions presented include gene-drug (pharmacogenetic), disease-drug, drug-drug, and natural product-drug interactions. Examples of multi-factorial PK interactions presented include drug-gene-drug, natural product-gene-drug, gene-gene-drug, disease-natural product-drug, and disease-gene-drug interactions. Clear interpretation of multi-factorial interactions can be complicated by study design, complexity in victim drug PK, and incomplete mechanistic understanding of victim drug PK.Expert opinion: Incorporation of complex multi-factorial PK interactions into precision drug therapy requires advances in clinical decision tools, intentional PK study designs, drug-metabolizing enzyme and transporter fractional contribution determinations, systems and computational approaches (e.g., physiologically-based pharmacokinetic modeling), and PK phenotyping of progressive diseases.

A comprehensive evaluation of single nucleotide polymorphisms associated with hepatocellular carcinoma risk in Asian populations: A systematic review and network meta-analysis

BACKGROUND

Single nucleotide polymorphisms (SNPs) have been inconsistently associated with hepatocellular carcinoma (HCC) risk. This meta-analysis aimed to synthesize relevant data on SNPs associated with HCC in the Asian population.

METHODS

Databases were searched to identify association studies of SNPs and HCC in Asians published through January 2019. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated based on 41 studies (13,167 patients with HCC and 15,886 noncancer controls). Network meta-analysis and Thakkinstian's algorithm were used to select the most appropriate genetic model, along with false positive report probability (FPRP) for noteworthy associations.

RESULTS

Eleven SNPs meeting the inclusion criteria were tested for association with HCC, including CCND1 rs9344, PTGS2 rs689466, IL18 rs187238 and rs1946518, KIF1B rs17401966, MDM2 rs2279744, MIR146A rs2910164, MIR149 rs2292832, MIR196A2 rs11614913, MIR499A rs3746444, and TGFB1 rs1800469. A significant increase for HCC risk was observed for MDM2 rs2279744, and the dominant (pooled OR = 1.59, 95% CI: 1.26-2.00) and codominant (pooled OR = 1.37, 95% CI: 1.18-1.60) models were determined to be the most appropriate models. MIR499A rs3746444 also showed a significant association with HCC risk under the allele contrast model (pooled OR = 1.36, 95% CI: 1.05-1.77). Only the significance of MDM2 rs2279744 was noteworthy (FPRP < 0.2).

CONCLUSIONS

MDM2 rs2279744 is associated with HCC susceptibility in Asians, and the dominant and codominant models are likely the most appropriate models to estimate HCC risk.

Cytochrome P450: Polymorphisms and Roles in Cancer, Diabetes and Atherosclerosis

Cytochromes P450s (CYPs) constitute a superfamily of enzymes that catalyze the metabolism of drugs and other substances. Endogenous substrates of CYPs include eicosanoids, estradiol, arachidonic acids, cholesterol, vitamin D and neurotransmitters. Exogenous substrates of CYPs include the polycyclic aromatic hydrocarbons and about 80% of currently used drugs. Some isoforms can activate procarcinogens to ultimate carcinogens. Genetic polymorphisms of CYPs may affect the enzyme catalytic activity and have been reported among different populations to be associated with various diseases and adverse drug reactions. With regard of drug metabolism, phenotypes for CYP polymorphism range from ultrarapid to poor metabolizers. In this review, we discuss some of the most clinically important CYPs isoforms (CYP2D6, CYP2A6, CYP2C19, CYP2C9, CYP1B1 and CYP1A2) with respect to gene polymorphisms and drug metabolism. Moreover, we review the role of CYPs in renal, lung, breast and prostate cancers and also discuss their significance for atherosclerosis and type 2 diabetes mellitus.

Downregulation of CYP2A6 and CYP2C8 in Tumor Tissues Is Linked to Worse Overall Survival and Recurrence-Free Survival from Hepatocellular Carcinoma

Objective

This study aimed to evaluate the links between CYP450 family genes in tumor tissues and hepatocellular carcinoma (HCC) outcomes.

Methods

Gene Expression Omnibus (GEO) databases GSE14520 and GSE36376 were used to identify differential expressed CYP450 genes between tumor and nontumor tissues and related to HCC clinicopathological features and survivals.

Results

Seven CYP450 genes including CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2E1, CYP3A4, and CYP4A11 were downregulated in tumor tissues, which were validated in both GSE14520 and GSE36376. HCC patients with CYP2A6 and CYP2C8 low levels in tumor tissues suffered from poorer overall survival (OS) compared to those with high CYP2A6 and CYP2C8 in GSE14520 profile (log ranks P = 0.01 and P = 0.006, respectively). In addition, HCC patients with lower CYP2A6 and CYP2C8 in tumors had worse recurrence-free survival (RFS) than those with higher CYP2A6 and CYP2C8 (log ranks P = 0.02 and P = 0.012, respectively). In GSE36376 validation dataset, HCC patients with lower CYP2A6 and CYP2C8 had worse OS and RFS than those with higher CYP2A6 and CYP2C8 (all P < 0.05), in line with results in GSE14520 dataset. Additionally, lower CYP2A6 and CYP2C8 are associated with advanced clinicopathological features including tumor staging, vascular invasion, intrahepatic metastasis, and high alpha fetoprotein (all P < 0.05).

Conclusion

Downregulation of CYP2A6 and CYP2C8 in tumor tissues links to poorer OS and RFS in HCC patients.

Significant change of cytochrome P450s activities in patients with hepatocellular carcinoma

The lack of information concerning individual variation in drug-metabolizing enzymes is one of the most important obstacles for designing personalized medicine approaches for hepatocellular carcinoma (HCC) patients. To assess cytochrome P450 (CYP) in the metabolism of endogenous and exogenous molecules in an HCC setting, the activity changes of 10 major CYPs in microsomes from 105 normal and 102 HCC liver tissue samples were investigated. We found that CYP activity values expressed as intrinsic clearance (CL_int) differed between HCC patients and control subjects. HCC patient samples showed increased CL_int for CYP2C9, CYP2D6, and CYP2E1 compared to controls. Meanwhile, CYP1A2, CYP2C8, and CYP2C19 CL_int values decreased and CYP2A6, CYP2B6, and CYP3A4/5 activity was unchanged relative to controls. For patients with HCC accompanied by fibrosis or cirrhosis, the same activity changes were seen for the CYP isoforms, except for CYP2D6 which had higher values in HCC patients with cirrhosis. Moreover, CYP2D6*10 (100C>T), CYP2C9*3 (42614 A>C), and CYP3A5*3 (6986A>G) polymorphisms had definite effects on enzyme activities. In the HCC group, the CL_int of CYP2D6*10 mutant homozygote was decreased by 95% compared to wild-type samples, and the frequency of this homozygote was 2.8-fold lower than the controls.

In conclusion, the activities of CYP isoforms were differentially affected in HCC patients. Genetic polymorphisms of some CYP enzymes, especially CYP2D6*10, could affect enzyme activity. CYP2D6*10 allelic frequency was significantly different between HCC patients and control subjects. These findings may be useful for personalizing the clinical treatment of HCC patients as well as predicting the risk of hepatocarcinogenesis.

Cytochrome P450 Genes (CYP2E1 and CYP1A1) Variants and Susceptibility to Chronic Hepatitis B Virus Infection

Hepatitis B virus (HBV) infection is a worldwide health concern which is associated with significant morbidity and mortality. Both viral and host factors have a significant effect on infection, replication and pathogenesis of HBV. The aim of this study was to investigate the effect of CYP2E1 and CYP1A1 genetic variants on susceptibility to HBV. 143 individuals including 54 chronic HBV patients and 89 healthy controls were enrolled in the genotyping procedure. rs2031920 and rs3813867 at CYP2E1 as well as rs4646421 and rs2198843 at CYP1A1 loci were studied in all subjects using PCR-RFLP (restriction fragment length polymorphism) analysis. Both variants at CYP2E1 locus were monomorphic in all studied subjects. Genotype frequency of rs4646421 was significantly different between chronic HBV patients and healthy blood donors (P = 0.04, OR 4.31; 95% CI 1.04-17.7). Furthermore, individuals carrying at least one C allele (CC or CT genotypes) for rs4646421 seemed to have a decrease risk of hepatitis in comparison with TT genotype (P = 0.039). Our results showed a relationship between rs4646421 TT genotype (rare genotype) and the risk for developing chronic HBV infection (four times higher). Further studies are needed to examine the role of CYP1A1 polymorphism in susceptibility to chronic HBV infection.

Meta-analysis of CYP2E1 polymorphisms in liver carcinogenesis

BACKGROUND

The CYP2E1 protein is a monooxygenase with certain polymorphisms linked to liver cancer. However, results from individual studies remain controversial.

AIMS

To evaluate CYP2E1 polymorphisms in liver carcinogenesis through meta-analysis.

METHODS

All studies about CYP2E1 polymorphisms and liver cancer were retrieved from seven major databases. Original data from each study were pooled and re-analyzed.

RESULTS

Total of 16 articles with 4862 cases were selected, including 1820 cases of liver cancer and 3042 cases of controls. The c1 allelic frequency in the cases and controls was 83.3% and 85.3%, respectively. Five genetic variations were compared: dominant c1c2/c2c2 vs. c1/c1 (OR=0.987 (0.853, 1.141)), homozygous c2c2 vs. c1c1 (OR=0.767 (0.526, 1.119)), heterozygous c1c2 vs. c1c1 (OR=1.005 (0.854, 1.182)), recessive c2c2 vs. c1c2/c2c2 (OR=0.771 (0.530, 1.122)), and different alleles c2 vs. c1 (OR=0.947 (0.828, 1.082)). Pooled data were further analyzed based on ethnicity, control sources, and HWE (Hardy-Weinberg equilibrium). These results from stratified groups were similar to that of nonstratified groups.

CONCLUSIONS

Our meta-analysis results suggest that there is no evidence for a major role of CYP2E1 polymorphism in liver carcinogenesis, but do not rule out the possibility in certain cases.

Genetic Polymorphisms of Cytochrome P4501A1 (CYP1A1) and Glutathione S-Transferase P1 (GSTP1) and Risk of Hepatocellular Carcinoma Among Chronic Hepatitis C Patients in Egypt

Cytochrome P450 1A1 (CYP1A1) and Glutathione S-transferase P1 (GSTP1) genes are involved in the metabolism of many carcinogens. Polymorphisms in these genes with altered enzyme activity have been reported. The present study evaluated the synergistic effect between CYP1A1 and GSTP1 gene polymorphisms and smoking on development of HCV-related liver disease and hepatocellular carcinoma (HCC). The patients group comprised 40 patients with HCC and 40 patients with liver cirrhosis. The control group comprised 40 healthy subjects having no history of malignancy. The genetic polymorphisms were studied using polymerase chain reaction restriction fragment length polymorphism (PCR RFLP) technique on blood samples. The number of current or former smoker among HCC and cirrhotic patients as well as the median Pack/year of cigarette smoked were significantly higher in HCC and liver cirrhotic patients than in control group. Subjects with CYP1A1 gene variants (m1 and m3) had no significant risk to develop cirrhosis or HCC compared to control group. Individuals carrying the Ile/Val genotype of GSTP1 had a significant increased risk of HCC (OR of 2.2, 95 % CI 1.143-4.261) and had larger tumor size. No significant risk was observed on combining both genes variants or on combining smoking with variants of both genes. In conclusion, the GSTP1 Ile/Val genotype and Val allele are associated with an increased risk of HCC. CYP1A1 and GSTP1 genes variants interaction did not increase the risk of HCC.

Modulation of ALDH5A1 and SLC22A7 by microRNA hsa-miR-29a-3p in human liver cells

Observed variations in drug responses among patients may result from differences in heritable genetic traits or from alterations in the epigenetic regulation of drug metabolizing enzymes and transporters (DMETs). MicroRNAs (miRNAs), a group of small non-coding RNAs, provide an epigenetic mechanism for fine-tuning the expression of targeted DMET genes by regulating the efficiency of protein translation and by decreasing mRNA stability via enhanced degradation. In the current study we systematically screened 374 important genes encoding DMETs for potential response elements to hsa-miR-29a-3p, a highly abundant miRNA in human liver. RNA electrophoresis mobility shift assays displayed direct interactions between hsa-miR-29a-3p and its cognate targets within the mRNA transcripts for the ABCC6, SLC22A7 and ALDH5A1 genes. The expression of luciferase reporter genes containing the 3'-UTRs of SLC22A7 or ALDH5A1 and the expression of endogenous SLC22A7 and ALDH5A1 were each suppressed by transfection with hsa-miR-29a-3p mimics. Importantly, chemically-induced up-regulation of hsa-miR-29a-3p correlated inversely with the expression of SLC22A7 and ALDH5A1. However, our studies failed to detect suppressive effects of hsa-miR-29a-3p on ABCC6 expression, which might be explained by the notion that the interaction of hsa-miR-29a-3p and ABCC6 mRNA was unable to recruit ribonucleoproteins to form a RNA-induced silencing complex.

Suppression of CYP2C9 by microRNA hsa-miR-128-3p in human liver cells and association with hepatocellular carcinoma

Published studies have identified genetic variants, somatic mutations, and changes in gene expression profiles that are associated with hepatocellular carcinoma (HCC), particularly involving genes that encode drug metabolizing enzymes (DMEs). CYP2C9, one of the most abundant and important DMEs, is involved in the metabolism of many carcinogens and drugs and is down-regulated in HCC. To investigate the molecular mechanisms that control CYP2C9 expression, we applied integrative approaches including in silico, in vitro, and in vivo analyses to elucidate the role of microRNA hsa-miR-128-3p in the regulation of CYP2C9 expression and translation. RNA electrophoresis mobility shift assays demonstrated a direct interaction between hsa-miR-128-3p and its cognate target, the CYP2C9 transcript. Furthermore, the expression of a luciferase reporter gene containing the 3′-UTR of CYP2C9 and the endogenous expression of CYP2C9 were suppressed by transfection of hsa-miR-128-3p. Importantly, chemically-induced up- or down-regulation of hsa-miR-128-3p correlated inversely with the expression of CYP2C9. Finally, an association analysis revealed that the expression of hsa-miR-128-3p is inversely correlated with the expression of CYP2C9 in HCC tumor tissues. Altogether, the study helped to elucidate the mechanism of CYP2C9 regulation by hsa-miR-128-3p, and the inverse association in HCC.

The effect of CYP, GST, and SULT polymorphisms and their interaction with smoking on the risk of hepatocellular carcinoma

Aim. The aim of our study was to assess whether selected single nucleotide polymorphisms of CYP1A1 and 2E1, GSTM1, GSTT1, and SULT1A1 influence susceptibility towards HCC, considering their interaction with cigarette smoking. Methods. We recruited HCC cases and controls among patients admitted to the hospital "Agostino Gemelli," from January 2005 until July 2010. Odds ratios (OR) of HCC were derived from unconditional multiple logistic regression. Gene-gene and gene-smoking interaction were quantified by computing the attributable proportion (AP) due to biological interaction. Results. The presence of any CYP2E1 (*) 5B variant allele (OR: 0.23; 95% CI: 0.06-0.71) and CYP2E1 (*) 6 variant allele (OR: 0.08; 95% CI: 0.01-0.33) was inversely related to HCC. There was a borderline increased risk among carriers of combined CYP1A1 (*) 2A and SULT1A1 variant alleles (OR: 1.67; 95% CI: 0.97-3.24). A significant biological interaction was observed between GSTT1 and smoking (AP = 0.48; 95% CI: 0.001-0.815), with an OR of 3.13 (95% CI: 1.69-5.82), and borderline significant interaction was observed for SULT1A1 and smoking (AP = 0.36; 95% CI: -0.021-0.747), with an OR of 3.05 (95% CI: 1.73-5.40). Conclusion. CYP2E1 (*) 5B and CYP2E1 (*) 6 polymorphisms have a favourable effect on the development of HCC, while polymorphisms of GSTT1 and SULT1A1 might play role in increasing the susceptibility among smokers.

Cytochrome P450 in Cancer Susceptibility and Treatment

Cytochrome 450 (CYP450) designates a group of enzymes abundant in smooth endoplasmic reticulum of hepatocytes and epithelial cells of small intestines. The main function of CYP450 is oxidative catalysis of various endogenous and exogenous substances. CYP450 are implicated in phase I metabolism of 80% of drugs currently in use, including anticancer drugs. They are also involved in synthesis of various hormones and influence hormone-related cancers. CYP450 genes are highly polymorphic and their variants play an important role in cancer risk and treatment. Association studies and meta-analyses have been performed to decipher the role of CYP450 polymorphisms in cancer susceptibility. Cancer treatment involves multimodal therapies and evaluation of CYP450 polymorphisms is necessary for pharmacogenetic assessment of anticancer therapy outcomes. In addition, CYP450 inhibitors are being evaluated for improved pharmacokinetics and oral formulation of several anticancer drugs.

Activation of aflatoxin B1 by expression of human CYP1A2 polymorphisms in Saccharomyces cerevisiae

Human susceptibility to environmental carcinogens is highly variable and depends on multiple genetic factors, including polymorphisms in cytochrome P450 genes. Although epidemiological studies have identified individual polymorphisms in cytochrome P450 genes that may alter cancer risk, there is often conflicting data about whether such polymorphisms alter the genotoxicity of environmental carcinogens. This is particularly true of the CYP1A2 polymorphisms that confer differential activation of multiple human carcinogens. To determine whether a single cytochrome P450 polymorphism confers higher levels of carcinogen-associated genotoxicity, we chose an organism that lack enzymes to metabolically activate aflatoxins and expressed individual human P450 genes in budding yeast. We measured the frequencies of recombination, Rad51 foci formation, 7-methoxyresorufin O-demethylase activities, and the concentrations of carcinogen-associated DNA adducts in DNA repair proficient yeast expressing P450 polymorphisms after exposure to aflatoxin B1 (AFB1).We measured growth of rad4 rad51 cells expressing CYP1A2 polymorphisms while exposed to AFB1. We observed that there was significantly less AFB1-associated genotoxicity in yeast expressing CYP1A2 I386F, while yeast expressing CYP1A2 C406Y exhibited intermediate levels of genotoxicity compared to yeast expressing CYP1A2 D348N or wild type. We conclude that differences in carcinogen genotoxicity can be observed in yeast expressing different CYP1A2 alleles. This is the first report that carcinogen-associated P450 polymorphisms can be studied in yeast.

Identification of CYP2C9*2 allele in HepG2 cell line

BACKGROUND

Hepatoma is caused by many factors including alcohol, chemicals, viral infection, and chronic inflammation. Cytochrome P450 polymorphism plays an important role in its pathogenesis. CYP2D6, CYP2E1, and CYP1A1 have been identified to be related with hepatic carcinogenesis and tumor size and stage. However, no studies have been performed on CYP2C9, a major CYP in the liver and hepatoma.

AIM OF THE STUDY

To identify if there is polymorphism of CYP2C9 in a HepG2 cell line.

METHODS

A pair of primers was used to clone CYP2C9 exon 3 region and subsequently sequenced. The sequence was compared to normal CYP2C9 for identification of any mutation.

RESULTS

A point mutation was identified. It was located in the amino acid number 144 of CYP2C9 protein with the change of normal amino acid arginine into cysteine, which is the same as identified in poor metabolism patients as homozygous CYP2C9*2.

CONCLUSIONS

There is a mutation (CYP2C9*2/ CYP2C9*2) in a HepG2 cell line. Thus, polymorphism of CYP2C9 may also be involved in the carcinogenesis of hepatoma as CYPs2D6 and 2E1.

Relationship between XRCC1 and XPD polymorphisms and the risk of the development of hepatocellular carcinoma: A case-control study

Hepatocellular carcinoma (HCC) is a serious public health issue, the incidence of which is considered to be closely related to tobacco smoking, alcohol consumption, hepatitis B virus (HBV) infection and family history. The DNA repair system is an important protective mechanism against the development of malignant cells induced by internal and external environmental factors. The aim of this study was to investigate the association of polymorphisms of XRCC1-194, XRCC1-280 and XPD-312 DNA repair genes and the risk of development of HCC in Han Chinese patients. A case-control design was used including 252 HCC inpatients and 250 healthy controls recruited and matched by age, gender, tobacco smoking, alcohol consumption, HBV infection and family history. XPD Asp312Asn, XRCC1 Arg194Trp and XRCC1 Arg280His genes were examined using a sequencing assay method. Distributions of the genotype frequency and odds ratio (OR) between the two groups were analyzed. The results demonstrated that there was no significant difference in the frequencies of XPD Asp312Asn, XRCC1 Arg194Trp and XRCC1 Arg280His in the HCC cases and the control group. In the stratified analysis of different allele genotypes, the frequency of the XRCC1-194 site genotype was not significantly different between the case and control group. The presence of the XRCC1 280His genotype was associated with a significantly increased risk of HCC under conditions of HBV infection and family history [OR (95% CI): 1.68 (1.08-2.60), 4.20 (1.34-13.20), respectively]. Similarly, the XPD 312Asn significantly increased the risk of HCC under conditions of alcohol consumption, tobacco smoking, HBV infection and family history [OR (95% CI): 1.67 (1.10-2.60), 1.87 (1.18-2.96), 1.96 (1.24-3.10), 3.40 (1.32-8.76), respectively]. In conclusion, tobacco smoking and alcohol consumption are high risk factors of HCC for the XPD 312Asn genotype; HBV infection and family history increase the risk of HCC for the genotypes XRCC1 280His and XPD 312Asn.

CYP2E1 PstI/RsaI polymorphism and interaction with alcohol consumption in hepatocellular carcinoma susceptibility: evidence from 1,661 cases and 2,317 controls

Many studies have suggested that cytochrome P450 2E1 (CYP2E1) gene might be involved in the development of hepatocellular carcinoma (HCC). However, the results have been inconsistent. In this study, the authors performed a meta-analysis to clarify the association between Pst I/Rsa polymorphism in the CYP2E1 gene and HCC risk. PubMed and China National Knowledge Infrastructure were searched for eligible publications. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using fixed- or random-effects model. Fifteen studies (1,661 HCC cases and 2,317 controls) were identified for the data analysis. The overall result showed that there was no statistically significant association between CYP2E1 Pst I/Rsa polymorphism and HCC risk (c2/c2 vs. c1/c1, OR = 0.73, 95% CI 0.50-1.06; c1/c2 vs. c1/c1, OR = 1.00, 95% CI 0.76-1.33; c2/c2+ c1/c2 vs. c1/c1, OR = 0.99, 95% CI 0.77-1.26; c2/c2 vs. c1/c2+ c1/c1, OR = 0.73, 95% CI 0.50-1.06). Further stratified analyses indicated that the habitual alcohol drinkers with c2 alleles were more likely to develop HCC (OR = 1.73, 95% CI 1.19-2.51), compared with the non-habitual drinkers with c1 homozygote. The meta-analysis indicated that CYP2E1 Pst I/Rsa polymorphism was not associated with HCC risk, while the interaction between Pst I/Rsa polymorphism and alcohol consumption increased the risk of HCC.

Evaluation of the association studies of single nucleotide polymorphisms and hepatocellular carcinoma: a systematic review

PURPOSE

For decades of years, hundreds of candidate gene-based association studies explored the relationship between single nucleotide polymorphisms (SNPs) and hepatocellular carcinoma (HCC). There was no systematic review summarized the results of these association studies of candidate SNPs and HCC to date. In order to summarize the results of the association studies, we conducted a concise systematic review.

METHODS

By searching Pubmed database before October 2010, we reviewed all the association studies about candidate SNPs and HCC. If the eligible study number on a given SNP was more than three, we conducted a meta-analysis. We reported here only the overall positive-association results with statistical significance and evaluated the reliability of the associations by using false-positive report probability (FPRP) analysis and the Venice guidelines on genetic epidemiology studies.

RESULTS

Six SNPs of five genes (rs1800562 of HFE, rs17868323 and rs11692021 of UGT1A7, rs2279744 of MDM2, rs1143627 of IL-1B, and rs4880 of MnSOD) showed overall significant associations with HCC. The eligible number of the studies varied from three to nine. Two SNPs (rs1800562 of HFE and rs2279744 of MDM2) passed the FPRP threshold (FPRP < 0.20). According to the Venice guidelines, the associations between the two SNPs (rs1800562 and rs2279744) and HCC were of moderate evidence.

CONCLUSIONS

Two SNPs (rs1800562 of HFE and rs2279744 of MDM2) were associated with HCC with moderate epidemiological evidence and deserve further study and additional biological and clinical assessment.

Rationale and targets for antifibrotic therapies

We have made striking progress in our understanding of the biochemistry and cell biology that underlies liver fibrosis and cirrhosis, including the development of strategies and agents to prevent and reverse fibrosis and incipient cirrhosis. However, translation of this knowledge into clinical practice has been hampered by the limitation of many in vitro and in vivo models to confirm mechanisms and to test antifibrotic agents, as well as the lack of sensitive methodologies to quantify the degree of liver fibrosis and the dynamics of fibrosis progression or reversal. Furthermore, while cirrhosis and subsequent decompensation are accepted hard clinical end-points, fibrosis and fibrosis progression alone are merely plausible surrogates for future clinical deterioration. This review focuses on basic mechanisms that underlay liver fibrosis progression and reversal and optimized strategies for preclinical antifibrotic drug development and validation. Therapies include several drugs that are of proven safety for other indications, agents that interfere with major fibrogenic or fibrolytic mechanisms, targeted drug delivery to the fibrogenic liver cells, and their potential combinations with hepatocyte or stem cell replenishment.

Interaction between cytochrome P450 1A2 genetic polymorphism and cigarette smoking on the risk of hepatocellular carcinoma in a Japanese population

Limited epidemiological evidence suggests that genetic polymorphisms of drug-metabolizing enzymes such as cytochrome P450 (CYP), glutathione S-transferase (GST) and N-acetyltransferase (NAT) may be involved in tobacco-related hepatocarcinogenesis. We conducted a case-control study, including 209 incident cases with hepatocellular carcinoma (HCC) and two different control groups [275 hospital controls and 381 patients with chronic liver disease (CLD) without HCC], to investigate whether CYP1A1, CYP1A2, CYP2A6, CYP2E1, GSTM1 and NAT2 polymorphisms are related to the risk of HCC with any interaction with cigarette smoking. Overall, no significant associations with HCC were observed for any genotypes against either control group. However, we found a significant interaction (P = 0.0045) between CYP1A2 -3860G>A polymorphism and current smoking on HCC risk when we compared HCC cases with CLD patients; adjusted odds ratios [ORs; and 95% confidence intervals (CIs)] for G/A and A/A genotypes relative to G/G genotype were 0.28 (0.12-0.66) and 0.18 (0.04-0.94), respectively, among current smokers (P trend = 0.002), as compared with 1.28 (0.80-2.06) and 0.76 (0.34-1.71), respectively, among never/former smokers (P trend = 0.96). Similarly, in CYP1A2 G/G genotype, significant risk increase was observed for current smoking (OR = 4.08, 95% CI = 2.02-8.25) or more recent cigarette use (e.g. pack-years during last 5 years, P trend = 0.0003) but not in G/A and A/A genotypes combined (OR for current smoking = 1.39, 95% CI = 0.63-3.03; P trend for pack-years during last 5 years = 0.40). These results suggest that the CYP1A2 -3860G>A polymorphism modifies the smoking-related HCC risk among CLD patients.

Lack of association between the functional polymorphisms in the estrogen-metabolizing genes and risk for hepatocellular carcinoma

Estrogens have been proposed to act as tumor promoters and induce hepatocarcinogenesis. Recently, we observed a significant association between the risk for hepatocellular carcinoma and the polymorphisms of the estrogen receptor (ESR) alpha (ESR1) gene, supporting the hypothesis of involvement for the estrogen-ESR axis in the estrogen-induced hepatocarcinogenesis. In this study, based on another hypothesis in which estrogen metabolites can directly cause DNA damage and affect tumor initiation, we examined whether the polymorphisms of the estrogen-metabolizing enzymes (EME), which are involved in biogenesis (CYP17, CYP19), bioavailability (CYP1A1, CYP1B1), and degradation (catechol-O-methyltransferase) of the estrogens, have any bearing on the risk for hepatocellular carcinoma. Seven functional polymorphisms in five EMEs (CYP17 MspAI site, CYP19 Trp39Arg, Ile462Val and MspI site in CYP1A1, CYP1B1 Val432Leu, and Ala72Ser and Val158Met in catechol-O-methyltransferase) were genotyped in 434 patients with hepatocellular carcinoma and 480 controls by PCR-RFLP analysis. The associations between the polymorphisms and hepatocellular carcinoma risk were evaluated while controlling for confounding factors. No significant association with the risk for hepatocellular carcinoma was observed with the seven polymorphisms in hepatitis B virus carriers and non-hepatitis B virus carriers after correction for multiple comparisons. After stratification by common confounding factors of hepatocellular carcinoma, the EME polymorphism remained no significant association with the hepatocellular carcinoma risk. Furthermore, no signs of gene-gene interactions were observed for each combination of the seven polymorphisms. Our findings suggest that the polymorphisms of EMEs may not contribute significantly to the risk for hepatocellular carcinoma.

Common genetic variations of the cytochrome P450 1A1 gene and risk of hepatocellular carcinoma in a Chinese population

Cytochrome P450 1A1 is a major enzyme in the bioactivation of exogenous procarcinogens of hepatocellular carcinoma (HCC). However, the contribution of common genetic variants in CYP1A1 to the HCC risk in Chinese populations has not been thoroughly investigated. In this study, we examined the association between HCC and four selected tagging single nucleotide polymorphisms (SNPs) of CYP1A1, and the risk of CYP1A1 haplotypes/diplotypes in 1006 pathologically confirmed HCC patients and 1015 cancer-free controls, from a Han Chinese population. Haplotypes/diplotypes were constructed from observed genotypes using the Haplo.Stats program. Relative risk was estimated by using multivariable logistic regression method. To summarise, we detected an increased HCC risk in rs4646421 variant carriers (OR 1.30, 95% CI 1.05-1.61) and rs2198843 variant carriers (OR 1.33, 95% CI 1.05-1.69), and a reduced risk of HCC (OR 0.70. 95% CI 0.52-0.94) associated with homozygote carriers of rs4886605 variant. These association signals were also observed in non-smokers with rs4646421 (OR 1.56, 95% CI 1.16-2.08) and rs4886605 (OR 0.61, 95% CI 0.40-0.91). Compared to the most common CYP1A1 haplotype CCAG, the haplotype TTGC conferred an increased risk of HCC (OR 1.26, 95% CI 1.04-1.52). Similarly, the TTGC/TTGC diplotype conferred an increased risk of HCC compared with diplotype CCAG/CCAG (OR 2.06, 95% CI 1.23-3.45, P=0.006). Interestingly, the diplotype TTAC/CCAG also conferred an increased risk of HCC (OR 1.76, 95% CI 1.22-2.54, P=0.003). Our results suggested that common genetic variants in CYP1A1 may modulate the risk of developing HCC in the study population, particularly in non-smokers. However, our findings need to be validated in at least one independent study of Han Chinese population.

An Interethnic Comparison of Polymorphisms of the Genes Encoding Drug-Metabolizing Enzymes and Drug Transporters: Experience in Singapore

Much of the interindividual variability in drug response is attributable to the presence of single nucleotide polymorphisms (SNPs) in genes encoding drug-metabolizing enzymes and drug transporters. In recent years, we have investigated the polymorphisms in a number of genes encoding phase I and II drug-metabolizing enzymes including CYPIA1, CYP3A4, CYP3A5, GSTM1, NAT2, UGT1A1, and TPMT and drug transporter (MDR1) in three distinct Asian populations in Singapore, namely the Chinese, Malays, and Indians. Significant differences in the frequencies of common alleles encoding these proteins have been observed among these three ethnic groups. For example, the frequency of the variant A2455G polymorphism of CYP1A1 was 28% in Chinese and 31% in Malays, but only 18% in Indians. CYP3A4*4 was detected in two of 110 Chinese subjects, but absent in Indians and Malays. Many Chinese and Malays (61-63%) were homozygous for the GSTM1*0 null genotype compared with 33% of Indians. The frequency of the UGTIA1*28 allele was highest in the Indian population (35%) compared to similar frequencies that were found in the Chinese (16%) and Malay (19%) populations. More importantly, our experience over the years has shown that the pharmacogenetics of these drug-metabolizing enzymes and MDR1 in the Asian populations are different from these in the Caucasian and African populations. For example, the CYP3A4*1B allele, which contains an A-290G substitution in the promoter region of CYP3A4, is absent in all three Asian populations of Singapore studied, but occurs in more than 54% of Africans and 5% of Caucasians. There were no difference in genotype and allelic variant frequencies in exon 12 of MDR1 between the Chinese, Malay, and Indian populations. When compared with other ethnic groups, the distribution of the wild-type C allele in exon 12 in the Malays (34.2%) and Indians (32.8%) was relatively high and similar to the Japanese (38.55%) and Caucasians (41%) but different from African-Americans (15%). The frequency of wild-type TT genotype in Asians (43.5% to 52.1%) and Japanese (61.5%) was much higher than those found in Caucasians (13.3%). All the proteins we studied represent the primary hepatic or extrahepatic enzymes, and their polymorphic expression may be implicated in disease risk and the disposition of drugs or endogenous substances. As such, dose requirements of certain drugs may not be optimal for Asian populations, and a second look at the factors responsible for this difference is necessary.

Association of interferon regulatory factor-7 gene polymorphism with liver cirrhosis in chronic hepatitis C patients

BACKGROUND AND AIMS

Interferon (IFN) regulatory factor 7 (IRF-7) has been shown to play an essential role in the transcriptional activation of virus-inducible cellular genes, especially IFN genes. Polymorphisms of the IRF-7 gene may probably affect both the quality and the quantity of IRF-7. We investigated the role of IRF-7 polymorphisms in Japanese patients with chronic hepatitis C virus (HCV) infection.

METHODS

We studied a total of nine polymorphisms of the IRF-7 gene including SNP1047A/G (Lys/Glu) and SNP2157A/G (Gln/Arg) using the Taqman allelic discrimination and sequencing techniques in 406 Japanese patients with chronic HCV infection. We further performed functional analysis of SNP1047 and SNP2157 by transcriptional activation of the IFNA promoter.

RESULTS

We found that SNP1047AG and SNP2157AG genotypes were in complete linkage disequilibrium and were present in a significantly higher proportion in HCV-infected patients with cirrhosis (5.6%) than in those without cirrhosis (1.7%) (P=0.03). Multivariate analysis also revealed that SNP1047 and SNP2157 were independently associated with cirrhosis at an odds ratio of 2.5. Functional analysis revealed that SNP1047G and SNP2157G alleles increased IFNA expression.

CONCLUSION

SNP1047AG and SNP2157AG genotypes were strongly associated with cirrhosis. SNP1047G and SNP2157G alleles might be used as markers of host factors associated with a higher risk of cirrhosis in Japanese patients with chronic HCV infection.

Liver cirrhosis

Cirrhosis is defined as the histological development of regenerative nodules surrounded by fibrous bands in response to chronic liver injury, which leads to portal hypertension and end-stage liver disease. Recent advances in the understanding of the natural history and pathophysiology of cirrhosis, and in treatment of its complications, have resulted in improved management, quality of life, and life expectancy of patients. Liver transplantation remains the only curative option for a selected group of patients, but pharmacological treatments that can halt progression to decompensated cirrhosis or even reverse cirrhosis are currently being developed. This Seminar focuses on the diagnosis, complications, and management of cirrhosis, and new clinical and scientific developments.

Liver cirrhosis

Cirrhosis is defined as the histological development of regenerative nodules surrounded by fibrous bands in response to chronic liver injury, which leads to portal hypertension and end-stage liver disease. Recent advances in the understanding of the natural history and pathophysiology of cirrhosis, and in treatment of its complications, have resulted in improved management, quality of life, and life expectancy of patients. Liver transplantation remains the only curative option for a selected group of patients, but pharmacological treatments that can halt progression to decompensated cirrhosis or even reverse cirrhosis are currently being developed. This Seminar focuses on the diagnosis, complications, and management of cirrhosis, and new clinical and scientific developments.

In Vitro Bioactivation of 3-(N-Phenylamino)propane-1,2-diol by Human and Rat Liver Microsomes and Recombinant P450 Enzymes. Implications for Toxic Oil Syndrome

Toxic oil syndrome (TOS) was a massive food-borne intoxication that occurred in Spain in 1981. Epidemiological studies imputed 3-( N-phenylamino)propane-1,2-diol (PAP) derivatives as the toxic agents. The in vitro bioactivation of PAP by rat and human liver microsomes was studied. In both cases, 3-[ N-(4'-hydroxyphenyl)amino]propane-1,2-diol ( 1) was detected as the main metabolite. Inhibition studies with pooled human liver microsomes in the presence and absence of P450-specific inhibitors suggest that 2C8 and 2E1 are the main enzymes involved in PAP bioactivation, followed by 3A4/5, 1A1/2, and 2C9. Incubations of PAP with 10 different recombinant P450 enzymes showed that 2C8, 2C9, 2C18, 2D6, and 2E1 catalyzed PAP 4'-hydroxylation. Incubations of phenol 1 with rat and human liver microsomes in the presence of GSH resulted in the formation of a glutathione conjugate of a quinoneimine metabolite derived from 1. In rat liver microsomes, P450 enzymes play a key role in the bioactivation of 1, whereas in human liver microsomes, autoxidation appears to be the major mechanism. The implications of these results for toxic oil syndrome are discussed.

MDM2 promoter SNP309 is associated with the risk of hepatocellular carcinoma in patients with chronic hepatitis C

PURPOSE

A single nucleotide polymorphism (SNP) in the promoter region of MDM2 gene, SNP309, has recently been shown to be associated with accelerated tumor formation in both hereditary and sporadic cancers in humans. However, the association of SNP309 with hepatocellular carcinoma is unknown. We evaluated the association of SNP309 with the risk of hepatocellular carcinoma development among Japanese patients with chronic hepatitis C virus infection.

EXPERIMENTAL DESIGN

We genotyped the SNP309 at the MDM2 promoter in 435 Japanese patients with chronic hepatitis C virus infection, including 187 patients with hepatocellular carcinoma and 48 healthy subjects, using a fluorogenic PCR. Presence of SNP was also confirmed by direct sequencing of the MDM2 promoter region.

RESULTS

The proportion of G/G genotype of the SNP309 in patients with hepatocellular carcinoma (33%) was significantly higher than that in patients without hepatocellular carcinoma (23%), with an odds ratio (95% confidence interval) of 2.28 (1.30-3.98). A multivariate analysis revealed that MDM2 SNP309 (G/G versus T/T), age >60 years, male gender, presence of cirrhosis, serum alpha-fetoprotein >20 mug/L, and serum albumin <3.2 g/dL were independently associated with the hepatocellular carcinoma development at odds ratio of 2.27, 2.46, 3.08, 4.15, 4.87, and 6.33, respectively.

CONCLUSIONS

The MDM2 promoter SNP309 is associated with the presence of hepatocellular carcinoma in Japanese patients with chronic hepatitis C.

Role of CYP2D6 polymorphism in predicting liver fibrosis progression rate in Caucasian patients with chronic hepatitis C

OBJECTIVE

Previous studies have demonstrated that CYP2D6 polymorphism is associated with liver cirrhosis. The aim of the present study was to find out whether CYP2D6*4, the poor metabolizer allele can predict fibrosis progression rate.

METHODS

Seventy-five Caucasian patients with chronic hepatitis C infection were recruited. They were divided into two groups, 'fast fibrosers' and 'slow fibrosers', according to Poynard's fibrosis progression curves. Sixty-two patients underwent liver biopsy. Twenty healthy neonates were included as control population. DNA was extracted from peripheral blood and CYP2D6*4 was tested by polymer chain reaction using fluorescent hybridization probes in a lightCycler instrument.

RESULTS

Forty-two patients were classified as 'fast fibrosers' and 33 patients as 'slow fibrosers'. The frequency of CYP2D6*4 allele in the 'fast fibrosers' (34.5%) was significantly higher compared with the 'slow fibrosers' (15%) (P-value=0.007). There was no significant difference between the frequency of CYP2D6*4 in the 'slow fibrosers' (15%) compared with the controls (12.5%). Carrier state of CYP2D6*4 was the only covariate that was significantly positively correlated with fast progression to cirrhosis (odds ratio=6.5, P=0.01).

CONCLUSION

This study indicates for the first time that CYP2D6 genotype might be a significant predictor of liver fibrosis progression rate in chronic hepatitis C patients.

Toward the evaluation of function in genetic variability: characterizing human SNP frequencies and establishing BAC-transgenic mice carrying the human CYP1A1_CYP1A2 locus

Interindividual differences in human CYP1A1 and CYP1A2 expression appear to be associated with variability in risk toward various types of environmental toxicity and cancer. These two genes are oriented head-to-head on human chromosome 15; the 23.3-kb spacer region might contain distinct regulatory regions for CYP1A1 and distinct regulatory regions for CYP1A2, or the regulatory regions for the two genes might overlap one another. From 24 unrelated subjects of five major, geographically-isolated subgroups, we resequenced both genes (all exons and all introns) plus some 3' flanking sequences and the entire spacer region (39.6 kb total); 85 SNPs were found, 49 of which were not currently in the National Center for Biotechnology Information (NCBI) database. Of the 57 double-hit SNPs, we carried out SNP-typing in 94 Africans, 96 Asians, and 83 Caucasians and found striking ethnic differences in SNP frequencies and haplotype evolution; the two CYP1A1 SNPs and the one CYP1A2 SNP that are most commonly used in epidemiological studies were shown not to be representative haplotype tag SNPs across these three human subgroups. Four BAC-transgenic mouse lines, carrying the human CYP1A2 and 15,190 bp of 5' flank, expressed only negligible basal or inducible CYP1A2 mRNA. A fifth BAC-transgenic mouse line, carrying both the human CYP1A1 and CYP1A2 genes and ample amounts of 3' flanking sequences, plus all of the spacer region--in the absence of the mouse Cyp1a1 or Cyp1a2 genes--expressed the human CYP1A1 and CYP1A2 mRNA, protein and enzyme activities in liver and nonhepatic tissues very similar to that of the mouse. Comparison of this hCYP1A1_1A2 transgenic line with hCYP1A1_1A2 lines carrying other common human haplotypes will enable us to evaluate function in human CYP1A1_CYP1A2 locus variability, with regard to toxicity and cancer caused by combustion products.

Validation of in vitro cell models used in drug metabolism and transport studies; genotyping of cytochrome P450, phase II enzymes and drug transporter polymorphisms in the human hepatoma (HepG2), ovarian carcinoma (IGROV-1) and colon carcinoma (CaCo-2, LS180) cell lines

Human cell lines are often used for in vitro biotransformation and transport studies of drugs. In vivo, genetic polymorphisms have been identified in drug-metabolizing enzymes and ABC-drug transporters leading to altered enzyme activity, or a change in the inducibility of these enzymes. These genetic polymorphisms could also influence the outcome of studies using human cell lines. Therefore, the aim of our study was to pharmacogenotype four cell lines frequently used in drug metabolism and transport studies, HepG2, IGROV-1, CaCo-2 and LS180, for genetic polymorphisms in biotransformation enzymes and drug transporters. The results indicate that, despite the presence of some genetic polymorphisms, no real effects influencing the activity of metabolizing enzymes or drug transporters in the investigated cell lines are expected. However, this characterization will be an aid in the interpretation of the results of biotransformation and transport studies using these in vitro cell models.

Interactive effects between CYP1A1 genotypes and environmental polychlorinated dibenzo-p-dioxins and dibenzofurans exposures on liver function profile

Previous studies reported that polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) induced hepatic cytochrome P-4501A1 (CYP1A1). The aim of this study was to examine the interactive influence of CYP1A1 genotypes and PCDD/Fs exposure on liver function profile. PCDD/Fs levels and liver function parameters were determined in serum and correlated with genetic polymorphism of CYP1A1/Msp 1 in 225 human volunteers who had no or minimal occupational exposure to PCDD/F. The results showed that the highest glutamate pyruvate transaminase (GPT) activity levels were found in subjects with homozygous variant CYP1A1/Msp 1, followed by heterozygous variant, and finally homozygous wild type for those individuals whose serum PCDD/Fs levels were higher than 17.4 pg WHO-TEQ/g lipid. Data suggest that GPT activity levels may be modified by interaction of CYP1A1/Msp 1 genotype with dioxin after adjustment for age, alcohol consumption, and history of liver illness. Further studies are needed to characterize the variation in other related genes to verify whether a correlation exists between serum PCDD/Fs levels and adverse health effects.

Genetic association of paraoxonase-1 polymorphisms and chronic hepatitis C virus infection

BACKGROUND

Hepatitis C virus infection is associated with hepatic free radical formation and enhanced lipid peroxidation and an individual's antioxidant status may play an important role. Paraoxonase-1 is an esterase that degrades oxidised lipids. In the present study, we investigated the genetic association of the most important paraoxonase-1 gene polymorphisms and the susceptibility to HCV-related chronic hepatitis.

METHODS

Paraoxonase-1 polymorphisms at positions -107, 55 and 192 were analysed from the genomic DNA of 186 patients and 386 healthy volunteers, as well as the serum concentration of total peroxides and standard biochemical tests.

RESULTS

Patients with chronic hepatitis had a higher frequency of the RR isoform of the 192 polymorphism than healthy subjects (13% vs. 7%, P<0.05). There were no significant differences with respect to the -107 and 55 polymorphisms. The plasma concentration of peroxides was higher in patients with chronic hepatitis [349.5 (246.2-479.8) vs. 115.4 (95.7-172.3) mumol/L; P<0.001].

CONCLUSIONS

The present study suggests that the paraoxonase-1 192 polymorphism contributes, together with other polymorphisms, to the variations in the host response to HCV infection.

Large-scale search of single nucleotide polymorphisms for hepatocellular carcinoma susceptibility genes in patients with hepatitis C

Hepatitis C virus (HCV) infection is a major risk factor for developing hepatocellular carcinoma (HCC). The host genetic factors that are involved in the development of HCC in patients with HCV infection remain to be investigated. To search for single nucleotide polymorphisms (SNPs) in HCC susceptibility genes, 393 SNPs in 171 candidate genes were examined in 188 Japanese patients with chronic HCV infection, including 77 patients with HCC. HCC-related SNPs were then examined in another 188 patients (including 93 patients with HCC) with chronic HCV infection. Haplotype analyses of HCC-related genes were performed in a total of 376 patients. Of the 393 SNPs, 31 SNPs in 29 genes were significantly associated with HCC based on an initial screening (P < .05). Of these 31 SNPs, 3 SNPs of 3 genes (SCYB14, GFRA1, and CRHR2) were significantly associated with HCC in a secondary screening. Haplotype analyses of these 3 genes identified 2 haplotype blocks associated with HCC. In conclusion, these SNPs and haplotypes located in the SCBY14, CRHR2, and GFRA1 genes will be used as markers to identify a subgroup of Japanese patients with chronic HCV infection who are at high risk of developing HCC.

Host genetic determinants in hepatitis C virus infection

In addition to viral and environmental/behavioural factors, host genetic diversity is believed to contribute to the spectrum of clinical outcomes in hepatitis C virus (HCV) infection. This paper reviews the literature with respect to studies of host genetic determinants of HCV outcome and attempts to highlight trends and synthesise findings. With respect to the susceptibility to HCV infection, several studies have replicated associations of the HLA class II alleles DQB1(*)0301 and DRB1(*)11 with self-limiting infection predominantly in Caucasian populations. Meta-analyses yielded summary estimates of 3.0 (95% CI: 1.8-4.8) and 2.5 (95% CI: 1.7-3.7) for the effects of DQB1(*)0301 and DRB1(*)11 on self-limiting HCV, respectively. Studies of genetics and the response to interferon-based therapies have largely concerned single-nucleotide polymorphisms and have been inconsistent. Regarding studies of genetics and the progression of HCV-related disease, there is a trend with DRB1(*)11 alleles and less severe disease. Studies of extrahepatic manifestations of chronic HCV have shown an association between DQB1(*)11 and DR3 with the formation of cryoglobulins. Some important initial observations have been made with respect to genetic determinants of HCV outcome. Replication studies are needed for many of these associations, as well as biological data on the function of many of these polymorphisms.

Homozygosity for Pro of p53 Arg72Pro as a potential risk factor for hepatocellular carcinoma in Chinese population

AIM: Codon 72 exon 4 polymorphism (Arg72Pro) of the p53 gene has been implicated in cancer risk. Our objective was to investigate the possible association between p53 Arg72Pro polymorphism and susceptibility to hepatocellular carcinoma (HCC) among Chinese population.

METHODS: The p53 Arg72Pro genotypes were determined by PCR-based restriction fragment length polymorphism (RFLP) analysis in 507 HCC cases and 541 controls. Odds ratios (ORs) for HCC and 95% confidence intervals (CIs) from unconditional logistic regression models were used to evaluate relative risks. Potential risk factors were included in the logistic regression models as covariates in the multivariate analyses on genotype and HCC.

RESULTS: The frequencies for Pro and Arg alleles were 44.5%, 55.5% in HCC cases, and 40.3% and 59.7% in controls, respectively. The Pro allele was significantly associated with the presence of HCC (P = 0.05) and had a higher risk for HCC (OR = 1.19, 95% CI 1.00-1.41) as compared with the Arg allele. After adjusted for potential risk factors, Arg/Pro heterozygotes had an 1.21-fold increased risk (95% CI 0.82-1.78, P = 0.34) of HCC compared with Arg homozygotes, whereas the risk for Pro homozygotes was 1.79 (95% CI 1.06-3.01, P = 0.03) times higher than that for Arg homozygotes. Pro-allele carriers had a higher relative risk of HCC than the Arg-only carriers (adjusted OR = 1.33, 95% CI 0.92-1.92, P = 0.13), although the difference was not statistically significant.

CONCLUSION: Homozygosity for Pro of p53 Arg72Pro is potentially one of the genetic risk factors for HCC in Chinese population. The p53 Arg72Pro polymorphism may be used as a stratification marker in screening individuals at a high risk of HCC.

UDP-glucuronosyltransferase 1A7 genetic polymorphisms are associated with hepatocellular carcinoma in japanese patients with hepatitis C virus infection

PURPOSE

Genetic polymorphisms of UDP-glucuronosyltransferase 1A7 (UGT1A7), which detoxifies endogenous and environmental carcinogens, have been reported to be associated with hepatocellular carcinoma (HCC) in German populations. On the other hand, we reported that interleukin-1 beta (IL-1 beta) gene polymorphisms were associated with hepatitis C virus (HCV)-related HCC. In this study, we evaluated the association of both genes with the risk of HCC in Japanese HCV-infected patients.

EXPERIMENTAL DESIGN

Genetic polymorphisms of UGT1A7 and IL-1 beta were investigated in 280 Japanese patients (122 with HCC and 158 without HCC) with chronic HCV infections, by use of standard PCR-based genotyping techniques.

RESULTS

We designated the UGT1A7*1 allele (a haplotype conferring higher activity) as H and the *2, *3, and *4 alleles (haplotypes conferring lower activity) as L. The proportions of UGT1A7 L/L and H/L alleles (genotypes) in patients with HCC (25% and 45%, respectively) were higher than those in patients without HCC (15% and 39%, respectively) with odds ratios of 2.73 (95% confidence interval, 1.40-5.35) and 1.80 (95% confidence interval, 1.05-3.09), respectively, compared with the UGT1A7 H/H alleles. Multivariate analyses revealed that UGT1A7 L/L and IL-1 beta/-31T/T-511C/C genotypes, the presence of cirrhosis, age >60 years, male sex, and alpha-fetoprotein >20 microg/ml were associated with the presence of HCC (odds ratios, 2.33, 2.67, 4.20, 3.12, 3.09, and 2.90, respectively).

CONCLUSION

The UGT1A7 polymorphisms together with IL-1 beta were associated with the presence of HCC in Japanese HCV-infected patients.

Effect of inducible nitric oxide synthesis inhibitor on CYP1A2 protein expression in BCG-immune liver damage in mice

AIM: To study the effect of nitric oxide production on CYP1A2 protein expression in immune liver damage induced by Mycobacterium Calmette-Guerin (BCG) in mice.

METHODS: Immune liver damage was induced by intravenous injection of BCG (125 mg/kg) for 2 weeks in vivo. The hepatic tissues injury was estimated by histopathological H-E staining. The protein expression of CYP2E1 and iNOS in hepatic tissues was determined by the method of immunohistochemistry. The correlation between iNOS inducing and liver injury degree was observered by the method of demi-quantification image analysis.

RESULTS: Two weeks after of BCG injection, granuloma was easily observed, and over-expression of iNOS protein was detected in the granulomas. The decrease of CYP1A2 protein expression was observed in mice hepatic tissues. Aminoguanidine, a selective iNOS inhibitor, significantly inhibited iNOS protein expression, and reversed down-regulation of CYP1A2 protein induced by BCG-immune liver damage in mice.

CONCLUSION: Under the BCG-stimulated condition, nitric oxide production participates in the down-regulation of CYP1A2 protein expression induced by immune hepatic injury in mice.

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