Publisher Correction: Pulmonary venous circulating tumor cell dissemination before tumor resection and disease relapse.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Pazopanib and Fosbretabulin in recurrent ovarian cancer (PAZOFOS): A multi-centre, phase 1b and open-label, randomised phase 2 trial.

OBJECTIVE: Vascular co-option is a resistance mechanism to anti-angiogenic agents, but combinations of anti-vascular agents may overcome this resistance. We report a phase 1b and randomised phase 2 trial to determine the safety and efficacy of pazopanib with fosbretabulin. METHODS: Eligible patients had recurrent, epithelial ovarian cancer with a platinum-free interval (PFI) of 3 to 12 months. Patients were stratified according to PFI (>6 versus ≤6 months) and prior bevacizumab use. RESULTS: Twelve patients were treated in the phase 1b. Commonest grade ≥ 2 adverse events (AEs) were hypertension (100%), neutropenia (50%), fatigue (50%), vomiting (50%). There was one DLT (grade 3 fatigue). The recommended phase 2 dose level was fosbretabulin 54 mg/m2 on days 1, 8 and 15 and pazopanib 600 mg once daily (od), every 28 days, which was then compared to pazopanib 800 mg od in a randomised phase 2 trial. Twenty-one patients were randomised (1:1) in the phase 2 trial. In phase 1b and phase 2, four patients treated with pazopanib and fosbretabulin developed reversible, treatment-related cardiac AEs, leading to premature discontinuation of the study. In the phase 2 trial, the median PFS was 7.6 months (95% CI 4.1-not estimated) versus 3.7 months (95% CI 1.0-8.1) in favour of the experimental arm (HR 0.30, 95% CI 0.09-1.03, P = .06). CONCLUSIONS: It remains unclear whether pazopanib with with fosbretabulin is an efficacious regimen to treat epithelial ovarian cancer. Effective cardiac risk mitigation is needed to increase the tolerability and maximize patient safety in future trials.

Pulmonary venous circulating tumor cell dissemination before tumor resection and disease relapse.

Approximately 50% of patients with early-stage non-small-cell lung cancer (NSCLC) who undergo surgery with curative intent will relapse within 5 years1,2. Detection of circulating tumor cells (CTCs) at the time of surgery may represent a tool to identify patients at higher risk of recurrence for whom more frequent monitoring is advised. Here we asked whether CellSearch-detected pulmonary venous CTCs (PV-CTCs) at surgical resection of early-stage NSCLC represent subclones responsible for subsequent disease relapse. PV-CTCs were detected in 48% of 100 patients enrolled into the TRACERx study3, were associated with lung-cancer-specific relapse and remained an independent predictor of relapse in multivariate analysis adjusted for tumor stage. In a case study, genomic profiling of single PV-CTCs collected at surgery revealed higher mutation overlap with metastasis detected 10 months later (91%) than with the primary tumor (79%), suggesting that early-disseminating PV-CTCs were responsible for disease relapse. Together, PV-CTC enumeration and genomic profiling highlight the potential of PV-CTCs as early predictors of NSCLC recurrence after surgery. However, the limited sensitivity of PV-CTCs in predicting relapse suggests that further studies using a larger, independent cohort are warranted to confirm and better define the potential clinical utility of PV-CTCs in early-stage NSCLC.

Dynamics of circulating vascular endothelial growth factor-A predict benefit from antiangiogenic cediranib in metastatic or recurrent cervical cancer patients.

AIMS: There is a need for predictive and surrogate response biomarkers to support treatment with antiangiogenic vascular endothelial growth factor (VEGF) inhibitors. We aimed to identify a minimally-invasive biomarker predicting benefit from cediranib pretreatment or early during treatment in patients with recurrent or metastatic cervical cancer. METHODS: Blood samples were collected before treatment, during treatment and upon disease progression where appropriate from patients enrolled in CIRCCa, a randomised phase II trial of carboplatin and paclitaxel with or without cediranib. Plasma concentrations of VEGF-A, VEGF-receptor 2, Ang1 and Tie2 were measured using multiplex enzyme-linked immunosorbent assay. Pretreatment and temporal changes of the biomarkers were investigated using proportional hazard regression and unsupervised clustering analysis. RESULTS: Samples (n = 556) from 52 patients were analysed. VEGF-receptor 2 (P = .0006) and Tie2 (P = .04) were downregulated following cediranib, while VEGF-A (P = .0025) was upregulated. High Eastern Cooperative Oncology Group performance status (P = .02, hazard ratio [HR] = 2.15, 95% confidence interval [CI] 1.13-4.09) and low pretreatment Tie2 concentrations (P = .003, HR = 0.57, 95%CI 0.39-0.83) were independent prognostic factors associated with reduced progression-free survival. Two patterns of changes in VEGF-A following cediranib were identified. Patients with elevated VEGF-A in the first 3 treatment cycles, regardless of magnitude, had reduced progression-free survival in the placebo arm but improved survival with the addition of cediranib (P = .019, HR = 0.13, 95% CI 0.02-0.71). CONCLUSION: Patterns of early elevation in plasma VEGF-A should be studied further as a potential biomarker to predict treatment benefit from cediranib.

Circulating Tumor Cells Detected in the Tumor-Draining Pulmonary Vein Are Associated with Disease Recurrence after Surgical Resection of NSCLC.

Tumor recurrence after surgical resection of NSCLC obstructs long-term disease-free survival in approximately 50% of cases. Our data suggest that combining circulating tumor cell enumeration (as single cells or clusters) in tumor-draining pulmonary vein and peripheral blood (assessed by CellSearch) at the time of NSCLC surgery better identifies those patients at higher risk for lung cancer recurrence than does peripheral circulating tumor cell number alone.

Aortic Binding of AZD5248: Mechanistic Insight and Reactivity Assays To Support Lead Optimzation.

The oral dipeptidyl peptidase 1 (DPP1) inhibitor AZD5248 showed aortic binding in a rat quantitative whole-body autoradiography (QWBA) study, and its development was terminated prior to human dosing. A mechanistic hypothesis for this finding was established invoking reactivity with aldehydes involved in the cross-linking of elastin, a major component of aortic tissue. This was tested by developing a simple aldehyde chemical reactivity assay and a novel in vitro competitive covalent binding assay. Results obtained with AZD5248, literature compounds, and close analogues of AZD5248 support the mechanistic hypothesis and provide validation for the use of these assays in a two tier screening approach to support lead optimization. The strengths and limitations of these assays are discussed.

Optimisation of immunofluorescence methods to determine MCT1 and MCT4 expression in circulating tumour cells.

BACKGROUND: The monocarboxylate transporter-1 (MCT1) represents a novel target in rational anticancer drug design while AZD3965 was developed as an inhibitor of this transporter and is undergoing Phase I clinical trials ( http://www.clinicaltrials.gov/show/NCT01791595 ). We describe the optimisation of an immunofluorescence (IF) method for determination of MCT1 and MCT4 in circulating tumour cells (CTC) as potential prognostic and predictive biomarkers of AZD3965 in cancer patients. METHODS: Antibody selectivity was investigated by western blotting (WB) in K562 and MDAMB231 cell lines acting as positive controls for MCT1 and MCT4 respectively and by flow cytometry also employing the control cell lines. Ability to detect MCT1 and MCT4 in CTC as a 4(th) channel marker utilising the Veridex™ CellSearch system was conducted in both human volunteer blood spiked with control cells and in samples collected from small cell lung cancer (SCLC) patients. RESULTS: Experimental conditions were established which yielded a 10-fold dynamic range (DR) for detection of MCT1 over MCT4 (antibody concentration 6.25 µg/mL; integration time 0.4 seconds) and a 5-fold DR of MCT4 over MCT 1 (8 µg/100 µL and 0.8 seconds). The IF method was sufficiently sensitive to detect both MCT1 and MCT4 in CTCs harvested from cancer patients. CONCLUSIONS: The first IF method has been developed and optimised for detection of MCT 1 and MCT4 in cancer patient CTC.

Circulating biomarkers in hepatocellular carcinoma.

PURPOSE: Our aims are to determine levels of circulating cellular and protein biomarkers in hepatocellular carcinoma (HCC) patients and to analyse any relationships with clinical parameters. METHODS: Fifty-four consenting patients were recruited. Circulating tumour cells (CTCs) were enumerated (by CellSearch) and characterised via filtration [by isolation by size of epithelial tumour cells (ISET)] with downstream immunohistochemistry (IHC). Glypican-3 (GPC3) expression in tumour biopsies and CTCs (by IHC) was compared, and levels of circulating caspase-cleaved and full-length cytokeratin 18 (CK18, measured using M30 and M65 ELISAs) were examined as a putative prognostic factor and marker of tumour burden. RESULTS: CTCs were identified in 14 out of 50 (28%) patients by CellSearch and in 19 out of 19 (100%) patients by ISET. The presence of GPC3-positive CTCs by ISET was 100% concordant with the presence of GPC3-positive cells in the original tumour (n = 5). No statistically significant correlations were observed between CTC number and clinical characteristics, although trends were noted between CTC subtypes, Child-Pugh score and tumour node metastasis stage. Serum M30 and M65 levels (as continuous variables) significantly correlated with overall survival (OS) in a univariate analysis (p = 0.003 and p < 0.001, respectively); M65 levels remained statistically significant in a multivariate analysis (p = 0.029). CONCLUSIONS: This is the first study to detect GPC3-positive CTCs in HCC, important for drug development with this target. The significant association of circulating CK18 with OS in HCC further exemplifies the utility of circulating biomarkers in cancer.

An integrated characterization of serological, pathological, and functional events in doxorubicin-induced cardiotoxicity.

Many efficacious cancer treatments cause significant cardiac morbidity, yet biomarkers or functional indices of early damage, which would allow monitoring and intervention, are lacking. In this study, we have utilized a rat model of progressive doxorubicin (DOX)-induced cardiomyopathy, applying multiple approaches, including cardiac magnetic resonance imaging (MRI), to provide the most comprehensive characterization to date of the timecourse of serological, pathological, and functional events underlying this toxicity. Hannover Wistar rats were dosed with 1.25 mg/kg DOX weekly for 8 weeks followed by a 4 week off-dosing "recovery" period. Electron microscopy of the myocardium revealed subcellular degeneration and marked mitochondrial changes after a single dose. Histopathological analysis revealed progressive cardiomyocyte degeneration, hypertrophy/cytomegaly, and extensive vacuolation after two doses. Extensive replacement fibrosis (quantified by Sirius red staining) developed during the off-dosing period. Functional indices assessed by cardiac MRI (including left ventricular ejection fraction (LVEF), cardiac output, and E/A ratio) declined progressively, reaching statistical significance after two doses and culminating in "clinical" LV dysfunction by 12 weeks. Significant increases in peak myocardial contrast enhancement and serological cardiac troponin I (cTnI) emerged after eight doses, importantly preceding the LVEF decline to <50%. Troponin I levels positively correlated with delayed and peak gadolinium contrast enhancement, histopathological grading, and diastolic dysfunction. In summary, subcellular cardiomyocyte degeneration was the earliest marker, followed by progressive functional decline and histopathological manifestations. Myocardial contrast enhancement and elevations in cTnI occurred later. However, all indices predated "clinical" LV dysfunction and thus warrant further evaluation as predictive biomarkers.

Oxidative bioactivation of abacavir in subcellular fractions of human antigen presenting cells.

Human exposure to abacavir, a primary alcohol antiretroviral, is associated with the development of immunological drug reactions in individuals carrying the HLA risk allele B*57:01. Interaction of abacavir with antigen presenting cells results in cell activation through an Hsp70-mediated Toll-like receptor pathway and the provision of T-cell antigenic determinants. Abacavir's electrophilic aldehyde metabolites are potential precursors of neoantigens. Herein, we have used mass spectrometry to study the oxidative metabolism of abacavir in EBV-transformed human B-cells. RNA and protein were isolated from the cells and subjected to transcriptomic and mass spectrometric analyses to identify the redox enzymes expressed. Low levels of isomeric abacavir carboxylic acids were detected in subcellular fractions of EBV-transformed human B-cells incubated with abacavir. Metabolite formation was time-dependent but was not reduced by an inhibitor of Class I alcohol dehydrogenases. Relatively high levels of mRNA were detected for several redox enzymes, including alcohol dehydrogenase 5 (Class III), aldehyde dehydrogenases (ALDH3A2, ALDH6A1, and ALDH9A1), CYP1B1, CYP2R1, CYP7B1, and hydroxysteroid dehydrogenase 10. Over 2600 proteins were identified by mass spectrometry. More than 1000 of these proteins exhibited catalytic activity, and 80 were oxido-reductases. This is the first proteomic inventory of enzymes in antigen presenting cells. However, neither of the hepatic alcohol dehydrogenases of Class I which metabolize abacavir in vitro was expressed at the protein level. Nevertheless the metabolic production of abacavir carboxylic acids by B-cell fractions implies abacavir-treated immune cells might be exposed to the drug's protein-reactive aldehyde metabolites in vivo.

The role of microRNAs in the pathogenesis of MMPi-induced skin fibrodysplasia.

BACKGROUND: Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes involved in extracellular matrix (ECM) homeostasis. MMPs have been an attractive pharmacological target for a number of indications. However, development has been hampered by the propensity of compounds targeting these enzymes to cause connective-tissue pathologies. The broad-spectrum MMP-inhibitor (MMPi) AZM551248 has been shown to induce such effects in the dog. Histopathological changes were consistent with fibrodysplasia (FD), characterised by fibroblast proliferation and the deposition of collagen in the subcutaneous tissues. We conducted a time-course study administering 20mg/kg/day AZM551248 between 4 and 17 days. Cervical subcutaneous tissue and plasma were sampled during the time-course. miRNA expression profiles in subcutaneous skin specimens following the administration of AZM551248 were determined by high-throughput-sequencing. RESULTS: An increasing number of miRNAs were differentially expressed compared with vehicle treated control animals as the study progressed. Several of these were members of the miR-200 family and were significantly attenuated in response to MMPi. As the severity of FD increased at the later time-points, other miRNAs associated with TGFß synthesis and regulation of the acute inflammatory response were modulated. Evidence indicative of epithelial to mesenchymal transition was present at all study time points. Receiver operator curve (ROC) analysis revealed that miR-21 expression in the cervical subcutaneous tissue was a sensitive and specific biomarker of FD incidence. CONCLUSIONS: Our data reveal significant perturbations in canine skin miRNA expression in response to MMPi administration. Furthermore, we have identified dysregulated miRNAs that are associated with processes relevant to the key histopathological events of MMPi-induced FD.

T-cells from HLA-B*57:01+ human subjects are activated with abacavir through two independent pathways and induce cell death by multiple mechanisms.

Susceptibility to abacavir hypersensitivity has been attributed to possession of the specific human leukocyte antigen allele HLA-B*57:01. HLA-B*57:01-restricted activation of CD8+ T-cells provides a link between the genetic association and the iatrogenic disease. The objectives of this study were to characterize the functionality of drug-responsive CD8+ T-cell clones generated from HLA-B*57:01+ drug-naive subjects and to explore the relationship between abacavir accumulation in antigen presenting cells and the T-cell response. Seventy-four CD8+ clones expressing different Vß receptors were shown to proliferate and kill target cells via different mechanisms when exposed to abacavir. Certain clones were activated with abacavir in the absence of antigen presenting cells. Analysis of the remaining clones revealed two pathways of drug-dependent T-cell activation. Overnight incubation of antigen presenting cells with abacavir, followed by repeated washing to remove soluble drug, activated approximately 50% of the clones, and the response was blocked by glutaraldehyde fixation. In contrast, a 1 h antigen presenting cell pulse did not activate any of the clones. Accumulation of abacavir in antigen presenting cells was rapid (less than 1 h), and the intracellular concentrations were maintained for 16 h. However, intracellular abacavir was not detectable by mass spectrometry after pulsing. These data suggest that T-cells can be activated by abacavir through a direct interaction with surface and intracellular major histocompatibility complex (MHC) molecules. With the former, abacavir seemingly participates in the MHC T-cell receptor binding interaction. In contrast, the latter pathway likely involves MHC binding peptides displayed as a consequence of abacavir exposure, but not abacavir itself.

The development of in vitro culture methods to characterize primary T-cell responses to drugs.

Adverse drug reactions represent a major stumbling block to drug development and those with an immune etiology are the most difficult to predict. We have developed an in vitro T-cell priming culture method using peripheral blood from healthy volunteers to assess the allergenic potential of drugs. The drug metabolite nitroso sulfamethoxazole (SMX-NO) was used as a model drug allergen to establish optimum assay conditions. Naive T cells were cocultured with monocyte-derived dendritic cells at a ratio of 25:1 in the presence of the drug for a period of 8 days, to expand the number of drug-responsive T cells. The T cells were then incubated with fresh dendritic cells, and drug and their antigen responsiveness analyzed using readouts for proliferation, cytokine secretion, and cell phenotype. All five volunteers showed dose-dependent proliferation as measured by 5-(and 6)-carboxyfluorescein diacetate succinimidyl ester content and by (3)H-thymidine uptake. CD4 T cells that had divided in the presence of SMX-NO had changed from a naive phenotype (CD45RA+) to a memory phenotype (CD45RO+). These memory T cells expressed the chemokine receptors CCR2, CCR4, and CXCR3 suggesting a mixture of T(H)1 and T(H)2 cells in the responding population, with a propensity for homing to the skin. Drug stimulation was also associated with the secretion of a mixture of T(H)1 cytokines (interferon γ) and T(H)2 cytokines (interleukin [IL]-5 and IL-13) as detected by ELISpot. We are currently developing this approach to investigate the allergenic potential of other drugs, including those where an association between specific human leucocyte antigen alleles and susceptibility to an immunological reaction has been established.

Fibrodysplasia induced in dog skin by a matrix metalloproteinase (MMP) inhibitor--a mechanistic analysis.

Matrix metalloproteinase (MMP) inhibitors, candidate therapeutic agents for a number of diseases, are known to be associated with acute fibrosis-type adverse effects in a number of species, including humans. The broad-spectrum MMP inhibitor, AZM551248, has previously been shown to cause these effects in the dog. Changes were characterized by the abnormal and extensive proliferation of fibroblasts and the deposition of collagen particularly in the subcutaneous connective tissues (subcutis) and were termed fibrodysplasia (FD). We performed a time-course study in dogs using AZM551248 and sampled skin, subcutis, and plasma before and during the development of FD. Detailed histopathological analysis and global gene expression profiling were performed on the subcutaneous tissues. The gene expression analysis of the subcutis indicated that extracellular matrix (ECM) remodeling was initiated asymptomatically at or before the earliest time point, day 4, and this was associated with dysregulation of expression of a number of MMPs and proteolytic enzymes. At later time points, the FD became progressively more extensive and severe, and this was associated with gene expression changes characteristic of tissue fibrosis, for example those associated with procollagen synthesis and processing. We postulate that AZM551248 inhibition of MMP action within the subcutis modulates the activity of several transcription factors and this in turn upregulates expression of specific proteases which initiate ECM remodeling. Persistent MMP inhibition results in the progression of ECM remodeling, culminating in collagen deposition and overt fibrosis. Our data indicate that inhibition of MMPs 1, 2, 3, and 9 is a key early event in AZM551248-induced FD in dog subcutis.

Tesaglitazar, a dual PPAR-α/γ agonist, hamster carcinogenicity, investigative animal and clinical studies.

Tesaglitazar was developed as a dual peroxisome proliferator-activated receptor (PPARα/γ). To support the clinical program, a hamster carcinogenicity study was performed. The only neoplastic findings possibly related to treatment with tesaglitazar were low incidences of hemangioma and hemangiosarcoma in the liver of male animals. A high-power, two-year investigative study with interim necropsies was performed to further elucidate these findings. Treatment with tesaglitazar resulted in changes typical for exaggerated PPARα pharmacology in rodents, such as hepatocellular hypertrophy and hepatocellular carcinoma, but not an increased frequency of hemangiosarcomas. At the highest dose level, there was an increased incidence of sinusoidal dilatation and hemangiomas. No increased endothelial cell (EC) proliferation was detected in vivo, which was confirmed by in vitro administration to ECs. Immunohistochemistry and gene expression analyses indicated increased cellular stress and vascular endothelial growth factor (VEGF) expression in the liver, which may have contributed to the sinusoidal dilatation. A two-fold increase in the level of circulating VEGF was detected in the hamster at all dose levels, whereas no effect on VEGF was observed in patients treated with tesaglitazar. In conclusion, investigations have demonstrated that tesaglitazar does not produce hemangiosarcomas in hamster despite a slight effect on vascular morphology in the liver.

Generation and analysis of transcriptomics data.

Transcript profiling ("Transcriptomics") is a widely used technique that obtains information on the abundance of multiple mRNA transcripts within a biological sample simultaneously. Therefore, when a number of such samples are analysed, as in a scientific experiment, large and complex data sets are gene-rated. Here, we describe the use of one method commonly used to generate transcriptomics data, namely the use of Affymetrix GeneChip microarrays. Data generated in transcriptomics experiments can be analysed using a multitude of approaches, but a common goal is to identify those transcripts whose abundance is altered by the experimental conditions, or which differ between sets of samples. Here, we describe a simple approach, the calculation of the volcano score, which identifies transcripts with altered abundance, taking into account both the magnitude of the alteration and its statistical significance.

A role for the pregnane X receptor in flucloxacillin-induced liver injury.

UNLABELLED: Drug-induced liver injury (DILI) due to flucloxacillin is a rare but serious complication of treatment. There is some evidence that flucloxacillin is a human pregnane X receptor (PXR) agonist. This study was designed to investigate the relevance of PXR to flucloxacillin toxicity and to identify genes changing in expression in response to flucloxacillin. Changes in gene expression in human hepatocytes after treatment with 500 microM flucloxacillin for 72 hours were examined by expression microarray analysis. The ability of flucloxacillin to act as a PXR agonist was investigated with reporter gene experiments. Flucloxacillin DILI cases (n = 51), drug-exposed controls without toxicity (n = 64), and community controls (n = 90) were genotyped for three common PXR polymorphisms. Luciferase reporter assays were used to assess the significance of a promoter region PXR polymorphism. Seventy-two probe sets representing 50 different genes showed significant changes in expression of 1.2-fold or higher. Most genes showing changes greater than 3-fold were known to be rifampicin-responsive, and this suggested a PXR-dependent mode of regulation. Using a luciferase-everted repeat separated by 6 base pairs element construct, we confirmed that flucloxacillin was a PXR agonist. We found a difference in the distribution of a PXR polymorphism (rs3814055; C-25385T) between flucloxacillin DILI cases and controls with the CC genotype associated with an increased risk of disease (odds ratio = 3.37, 95% confidence interval = 1.55-7.30, P = 0.0023). Reporter gene experiments showed lower promoter activity for the C allele than the T allele. CONCLUSION: Flucloxacillin is a PXR agonist at pharmacologically relevant concentrations, and a functionally significant upstream PXR polymorphism is a risk factor for flucloxacillin-induced DILI.

Molecular and genetic association of interleukin-6 in tacrine-induced hepatotoxicity.

BACKGROUND: Tacrine, an anticholinesterase used to treat Alzheimer's disease (AD), leads to an increase in serum alanine aminotransferase (ALT) levels. The factors determining individual susceptibility are largely unknown. The purpose of this study was to investigate genetic predisposition. METHODS: Rats were administered single dose tacrine (3-40 mg/kg). After 6 and 24 h, hepatic gene expression was determined using the affymetrix rat U34A microarray. On the basis of the gene expression data, the IL6 gene was identified as a potential candidate for tacrine transaminitis susceptibility. Sixty-nine patients with AD on tacrine with or without transaminitis were genotyped for 17 IL6 polymorphisms. RESULTS: Serum aspartate aminotransferase levels in rats increased after tacrine (40 mg/kg) administration. Forty-six and 29 genes showed significant upregulation at 6 and 24 h, respectively, after administration, including the IL-6-regulated acute phase response genes alpha2-macroglobulin, fibronectin and haptoglobin. Five of the 17 IL6 polymorphisms studied in AD patients showed an association (P<0.05) with transaminitis [ALT>2 x upper limit of normal (ULN)]. An association existed between maximum ALT and area under curve for ALT over 15 weeks and an intronic polymorphism (P<0.01) and a 3'-variable nucleotide tandem repeat (P<0.05). Multilocus haplotype analysis showed one haplotype (which included the -597A, -572G, -174G and variable nucleotide tandem repeat-D alleles) had a frequency of 0.1 in patients with ALT values >2 x ULN, whereas it was absent in patients with ALT less than 2 x ULN (P=0.0093, Pcorrected=0.049). CONCLUSION: The IL6 genotype may act as a predisposing factor for tacrine transaminitis. This, however, requires further confirmatory functional studies. The role of acute dosing rodent models in identifying candidate genes associated with drug-induced liver injury in man deserves further study.

Tacrine-induced liver damage: an analysis of 19 candidate genes.

OBJECTIVES: Tacrine, the first acetylcholinesterase inhibitor used in the treatment of Alzheimer's disease, is associated with transaminase elevation in up to 50% of patients. The mechanism of tacrine-induced liver damage is not fully understood, but earlier studies have suggested that genetic factors may play a role. Our aim was to investigate whether single-nucleotide polymorphisms (SNPs) in 19 candidate genes were associated with tacrine-induced liver damage. METHODS: Sixty-nine patients of Caucasian origin treated with tacrine for Alzheimer's disease were investigated by genotyping 241 SNPs in 19 candidate genes potentially related to hepatotoxicity. The association with ABCB4 [which encodes MultiDrug Resistance Protein 3 (MDR3)] was explored in transepithelial transport studies using the ABCB4-transfected pig kidney epithelial cell line (LLC-PK1). RESULTS: The strongest association between alanine aminotransferase levels and three SNPs within ATP-binding cassette, subfamily B (MDR/TAP), member 4 (ABCB4) (uncorrected P=0.0005) was not significant after adjusting for multiple testing. No association was demonstrated with ATP-binding cassette, subfamily B (MDR/TAP), member 1 (ABCB1) or carnitine O-octanoyltransferase (CROT) which are located adjacent to ABCB4. Using the transepithelial transport system we failed to show a difference in tacrine accumulation between ABCB4-transfected and parental cell lines. The association with ABCB4 warrants further testing using either another population and/or functional studies.

Microarray analysis of gene expression of mouse hepatocytes of different ploidy.

Polyploidisation in hepatocytes has been associated with many physiologic and pathologic processes such as proliferation, metabolism, regeneration, aging, and cancer. We studied gene expression patterns in hepatocytes of different ploidy. Primary hepatocytes were obtained from mice of different ages: young (4-6 weeks old), adult (8-10 weeks old), and older (22-24 weeks old). Diploid (2N), tetraploid (4N), and octoploid (8N) hepatocytes were isolated for studies using a high-density mouse genome microarray. No major changes of gene expression patterns between hepatocytes of different ploidy were found. Fifty genes were identified as differentially expressed in the diploid and tetraploid populations, but the changes were less than twofold either way. Four genes (Gas2, Igfbp2, Nr1i3, and Ccne2) were differentially expressed in tetraploid and octoploid cells. This was confirmed in two age groups, "adult" and "older," but once again the factors were less than twofold and the expressions of Gas2 and Igfbp2 were more different between age groups than between ploidy classes. Our results show that polyploid hepatocytes are stable and "normal" without aberrant gene expression, unlike what is thought for cancer cells. By contrast to megakaryocytes, hepatocyte polyploidisation is not a differentiation step associated with major changes in gene expression. Our data support the hypothesis that hepatocyte polyploidisation is a protective mechanism against oxidative stress that occurs via a controlled process throughout growth and aging where binucleation is important.