studies

HEPATOLOGY, VOLUME 62, NUMBER 1 (SUPPL) AASLD ABSTRACTS 327A
showed enhanced mitochondrial translocation of JNK accompanied
by an increase in the release of mitochondrial enzymes,
such as apoptosis-inducing factor and endonuclease G, into
the cytosol, which is indicative of increased mitochondrial dysfunction
and subsequent nuclear DNA fragmentation. Finally,
in vitro experiments showed that Gab1-deficient hepatocytes
were more susceptible to APAP-induced mitochondrial dysfunction
and cell death, suggesting that hepatocyte Gab1 is a
direct target of APAP-induced hepatotoxicity. Conclusion: Our
current data demonstrate that hepatocyte Gab1 plays a critical
role in controlling the balance between hepatocyte death and
compensatory hepatocyte proliferation during APAP-induced
liver injury. Thus, hepatocyte Gab1 would be a potential therapeutic
target for APAP-induced liver injury.
Disclosures:
Tetsuo Takehara - Grant/Research Support: Chugai Pharmaceutical Co., MSD
K.K., Bristol-Meyer Squibb, Mitsubishi Tanabe Pharma Corparation, Toray Industories
Inc. ; Speaking and Teaching: MSD K.K., Bristol-Meyer Squibb, Janssen
Pharmaceutical Companies
The following authors have nothing to disclose: Yuichi Yoshida, Kunimaro Furuta,
Satoshi Ogura, Tomohide Kurahashi, Mayumi Egawa, Shinichi Kiso, Yoshihiro
Kamada
228
Lipotoxicity Accounts for Liver Injury due to Etomoxir:
Application of Systems Toxicology Modeling of a Patient
Population
Scott Q. Siler 1,2 , Yuching Yang 2,1 , Diane M. Longo 2,1 , Brett A.
Howell 2,1 , Paul Watkins 2 ; 1 DILI-sim, Castro Valley, CA; 2 Institute
for Drug Safety Sciences, The Hamner Institutes-University of North
Carolina, Research Triangle Park, NC
Background: Etomoxir reduces fatty acid oxidation by inhibiting
mitochondrial carnitine palmitoyltransferase 1 (CPT1).
Etomoxir was originally developed for treatment of type 2 diabetes
and congestive heart failure (CHF). In the “Etomoxir for
the Recovery of Glucose Oxidation” (ERGO) clinical trial for
CHF, elevations in serum ALT > 5 X ULN were observed in
4 patients receiving active treatment, causing termination of
the trial. It has remained unclear whether etomoxir hepatotoxicity
resulted from direct mitochondrial toxicity or lipotoxicity
due to the accumulation of lipids. Aim: To identify the
most likely mechanistic determinant of etomoxir hepatotoxicity
via simulations with DILIsym®. Methods: DILIsym®, a predictive,
mechanistic, mathematical model of drug-induced liver
injury (DILI), was used to simulate liver drug concentrations
and DILI responses after administration of etomoxir (80 mg
q.d.) in a virtual human population sample (SimPops) of 229
simulated individuals. Quantitative fatty acid inhibition effects
were based on in vitro data from the literature (Agius 1991).
The DILIsym® model consists of various sub-models that are
mathematically integrated to simulate patient response. The
current work utilized several components of DILIsym®, including
a physiologically-based pharmacokinetic (PBPK) sub-model
representing drug distribution, sub-models of mitochondrial
dysfunction and lipotoxicity, hepatocyte life cycle, and liver
injury biomarkers. SimPops has been created by varying
key parameters consistent with experimental data. DILIsym®
is developed and maintained through the DILI-sim Initiative,
a public-private partnership involving scientists in academia,
industry, and the FDA. Results: In simulations where the model
parameters excluded contributions of lipotoxicity to liver injury,
no simulated patients were predicted to experience serum ALT
increases. However, simulations including lipotoxicity showed
an incidence of DILI that was similar to that seen in the ERGO
trial, with 2-3% of simulated patients predicted to have ALT >5x
ULN. The predicted ALT increases did not occur until after 4-6
weeks of dosing, as was observed in the ERGO trial. Conclusions:
The DILIsym® simulation results suggest that hepatotoxicity
observed in the ERGO trial resulted from accumulation of
lipids leading to lipotoxicity and not direct mitochondrial toxicity.
This study illustrates the capability of DILIsym® to combine
clinical data, in vitro data, predicted liver compound exposure,
and inter-patient differences to provide insight into underlying
mechanisms causing DILI.
Disclosures:
The following authors have nothing to disclose: Scott Q. Siler, Yuching Yang,
Diane M. Longo, Brett A. Howell, Paul Watkins
229
HCV Core Gene Mutations with Heightened Liver Cancer
Risk: Impact on Cellular Gene Expression
Ahmed M. Elshamy 1 , Francis J. Eng 1 , Erin H. Doyle 1 , Arielle L. Klepper
1 , Xiaochen Sun 1 , Angelo Sangiovanni 2 , Massimo Iavarone 2 ,
Massimo Colombo 2 , Robert E. Schwartz 3 , Yujin Hoshida 4 , Andrea
D. Branch 1 ; 1 Liver Diseases, Icahn School of Medicine at Mount
Sinai, New York, NY; 2 M. & A. Migliavacca Center for Liver Disease
and 1st Division of Gastroenterology, Fondazione IRCCS
Cà Granda Ospedale Maggiore Policlinico, University of Milan,
Milan, Italy; 3 Department of Medicine, Weill Cornell Medical College,
Department of Physiology, Biophysics, and Systems Biology,
Weill Cornell Medical College, New York, NY; 4 Liver Cancer
Program, Tisch Cancer Institute, Division of Liver Diseases, Department
of Medicine, Icahn School of Medicine at Mount Sinai, New
York, NY
Background and Aims: Patients infected by genotype-1b hepatitis
C virus (HCV) with Q 70 and/or M 91 core gene mutations
have an almost five-fold increased risk of developing hepatocellular
carcinoma (HCC) and an increased susceptibility to
insulin resistance. The elevated HCC risk persists despite a sustained
virological response to treatment. These compelling clinical
data prompted us to seek laboratory data corroborating
the oncogenic effects of the Q 70 /M 91 mutations. Methods: The
HCC-associated virus (Q 70 /M 91 ) and the control virus (R 70 /
L 91 ) were studied in Huh-7 cells. Infected cells were cultured
in media containing adult human serum to promote differentiation.
Quantitative RT-PCR and genome-wide transcriptome
profiling (HumanHT12 beadarray, Illumina) were used for RNA
analysis. Modulated molecular pathways were determined by
Gene Set Enrichment Analysis. For clinical validation, transcriptomes
of infected cells were compared to those of liver
biopsies of patients with early-stage HCV-related cirrhosis who
were followed prospectively for up to 23 yr to monitor for
HCC and other clinical outcomes (n=216). Results: The Huh-7
cells cultured in human serum acquired several features of differentiated
hepatocytes, including a cobble-stone morphology
and significantly enhanced expression of albumin and other
hepatocyte-specific genes. Their expression of albumin was
similar to that of cultured primary human hepatocytes and ~
20-fold higher than that of Huh-7 cells maintained in media
containing fetal bovine serum. Surprisingly, although the two
viruses were virtually identical in virological fitness, they had
markedly different effects on cellular gene expression. The highrisk
virus (Q 70 /M 91 ) enhanced expression of pathways associated
with cancer and type II diabetes, while the control virus
(R 70 /L 91 ) enhanced pathways associated with oxidative phosphorylation.
Of special clinical relevance, the transcriptome of
cells replicating the high-risk virus correlated significantly with
an HCC-associated transcriptome in patients (Bonferroni-corrected
P=0.03), but not with any other outcome-related transcriptome.
The transcriptome of cells replicating the control
virus did not correlate with any outcome-related transcriptome.