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The generation of reactive metabolites from therapeutic agents is one of the major mechanisms of drug-induced liver injury (DILI). In order to evaluate metabolism-related toxicity and improve drug efficacy and safety, we generated a battery of HepG2-derived cell lines that express 14 cytochrome P450s (CYPs) (1A1, 1A2, 1B1, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 3A4, 3A5 and 3A7) individually using a lentiviral expression system. The expression/production of a specific CYP in each cell line was confirmed by an increased abundance of the CYP at both mRNA and protein levels. Moreover, the enzymatic activities of representative CYPs in the corresponding cell lines were also measured. Using our CYP-expressed HepG2 cells, the toxicity of three drugs that could induce DILI (amiodarone, chlorpromazine and primaquine) was assessed, and all of them showed altered (increased or decreased) toxicity compared to the toxicity in drug-treated wild-type HepG2 cells. CYP-mediated drug toxicity examined in our cell system is consistent with previous reports, demonstrating the potential of these cells for assessing metabolism-related drug toxicity. This cell system provides a practical in vitro approach for drug metabolism screening and for early detection of drug toxicity. It is also a surrogate enzyme source for the enzymatic characterization of a particular CYP that contributes to drug-induced liver toxicity. [ABSTRACT FROM AUTHOR]

Abstract: Sertraline is used for the treatment of depression, and is also used for the treatment of panic, obsessive-compulsive, and post-traumatic stress disorders. Previously, we have demonstrated that sertraline caused hepatic cytotoxicity, with mitochondrial dysfunction and apoptosis being underlying mechanisms. In this study, we used microarray and other biochemical and molecular analyses to identify endoplasmic reticulum (ER) stress as a novel molecular mechanism. HepG2 cells were exposed to sertraline and subjected to whole genome gene expression microarray analysis. Pathway analysis revealed that ER stress is among the significantly affected biological changes. We confirmed the increased expression of ER stress makers by real-time PCR and Western blots. The expression of typical ER stress markers such as PERK, IRE1α, and CHOP was significantly increased. To study better ER stress-mediated drug-induced liver toxicity; we established in vitro systems for monitoring ER stress quantitatively and efficiently, using Gaussia luciferase (Gluc) and secreted alkaline phosphatase (SEAP) as ER stress reporters. These in vitro systems were validated using well-known ER stress inducers. In these two reporter assays, sertraline inhibited the secretion of Gluc and SEAP. Moreover, we demonstrated that sertraline-induced apoptosis was coupled to ER stress and that the apoptotic effect was attenuated by 4-phenylbutyrate, a potent ER stress inhibitor. In addition, we showed that the MAP4K4-JNK signaling pathway contributed to the process of sertraline-induced ER stress. In summary, we demonstrated that ER stress is a mechanism of sertraline-induced liver toxicity. [Copyright &y& Elsevier]

Abstract: The advent of next generation sequencing (NGS) technologies has revolutionized the field of genomics, enabling fast and cost-effective generation of genome-scale sequence data with exquisite resolution and accuracy. Over the past years, rapid technological advances led by academic institutions and companies have continued to broaden NGS applications from research to the clinic. A recent crop of discoveries have highlighted the medical impact of NGS technologies on Mendelian and complex diseases, particularly cancer. However, the ever-increasing pace of NGS adoption presents enormous challenges in terms of data processing, storage, management and interpretation as well as sequencing quality control, which hinder the translation from sequence data into clinical practice. In this review, we first summarize the technical characteristics and performance of current NGS platforms. We further highlight advances in the applications of NGS technologies towards the development of clinical diagnostics and therapeutics. Common issues in NGS workflows are also discussed to guide the selection of NGS platforms and pipelines for specific research purposes. [Copyright &y& Elsevier]

Amiodarone is a widely used potent antiarrhythmic for the treatment of cardiac disease; however, its use is often discontinued due to numerous adverse effects, including hepatotoxicity. To investigate the role of drug metabolism in this liver toxicity, amiodarone and its major metabolite desethylamiodarone were incubated with HepG2 cells overexpressing a series of cytochrome P450 (CYP) isoforms. Significantly higher cytotoxicity of amiodarone was observed in HepG2 cells overexpressing CYP3A4 or CYP1A1, compared with that observed in empty vector transduced control cells. Further, higher levels of the more potent hepatotoxic metabolite desethylamiodarone were detected in CYP3A4 or CYP1A1 expressed cells. The CYP3A4 inhibitor ketoconazole and the CYP1A1 inhibitor α-naphthoflavone drastically inhibited the metabolism of amiodarone to desethylamiodarone. Along with the inhibition of CYP1A1 or CYP3A4, the cytotoxicity of amiodarone was significantly reduced. These data indicate that the metabolism of amiodarone to desethylamiodarone by CYP1A1 or CYP3A4 plays an important role in the hepatocellular toxicity of amiodarone. [ABSTRACT FROM AUTHOR]

Abstract: Several lines of evidence suggest that the human 5-HT7 receptor may be involved in the pharmacodynamics of risperidone and may influence clinical response of the drug. A pharmocogenetics study of this receptor may therefore be useful in developing individualized therapy. But few studies about it have been done. In this study, we genotyped ten single nucleotide polymorphisms (SNPs) distributed throughout the HTR7 gene and analyzed six of them for association with the reduction of Brief Psychiatric Rating Scale (BPRS) scores in drug-naive Chinese schizophrenia patients, following an eight-week period of risperidone monotherapy. The confounding effects of nongenetic factors were estimated and the baseline symptom score as well as the duration of illness were included as covariates for adjustment. No significant correlation of HTR7 with antipsychotic efficacy was detected in either genotype or haplotype analysis. These results demonstrate that variations in the HTR7 gene may not be good genetic markers for predicting the therapeutic efficacy of risperidone. [Copyright &y& Elsevier]

Abstract: A number of studies have investigated the effectiveness of the dopamine transporter (SLC6A3) Gene as an antipsychotic target. However, the focus has mainly been on a 40-bp variable number of a tandem repeat (VNTR) in the 3′-region and results have been inconsistent. To fully evaluate SLC6A3 as a therapeutic antipshycotic target we investigated association of the gene with responses to chlorpromazine and clozapine and with chlorpromazine-induced extrapyramidal syndrome (EPS) in the Chinese schizophrenia population. Six polymorphisms across the whole region of this gene were analyzed, namely rs2652511 (T-844C) and rs2975226 (T-71A) in the 5′-regulatory region, rs2963238 (A1491C) in intron 1, a 30-bp VNTR in intron 8, rs27072 and the 40-bp VNTR in the 3′-region. We found that the polymorphic marker, rs2975226, showed significant association of allele and genotype frequencies with response to clozapine (allele-wise: adjusted p =0.00404; genotype-wise: adjusted p =0.024), and that patients with the T allele had a better response to the drug. The haplotype block constructed from the first three markers near the 5′-region showed significant association with response to clozapine (for haplotype T-T-A: p =0.0085; for haplotype C-A-C: p =0.0092). We did not identify any significant association of the six genetic variants or haplotypes with EPS after Bonferoni correction. Our findings suggest that the 5′-regulatory region of SLC6A3 plays an important role in response to clozapine and that its role in EPS needs to be replicated in a large-scale well designed study. [Copyright &y& Elsevier]

Abstract: In this study, variants of two genes coding for cytochrome P450 enzyme (CYP3A4 and CYP3A5) were analysed in a case–control sample using 398 schizophrenic patients and 391 healthy controls. All subjects were unrelated Han Chinese from Shanghai. No difference was observed on the allelic or genotypic distribution of CYP3A4 and CYP3A5 gene polymorphisms between the groups. However, the two-marker haplotypes covering components CYP3A4⁎1G and CYP3A5⁎3 were observed to be significantly associated with schizophrenia (corrected global p =0.0009). In addition, we identified one common risk haplotype, G/G (present in 59.5% of the general population). The results suggest that CYP3A4 and CYP3A5 might play a role in genetic susceptibility to schizophrenia. However, confirmatory studies in independent samples are needed. [Copyright &y& Elsevier]