The Toxicologist - Society of Toxicology

model of APAP metabolism and glutathione depletion has been used to investigate
the extent to which differences in metabolism and glutathione homeostasis explain
interspecies differences in susceptibility to APAP toxicity. As compounds with other
modalities of DILI are added to the platform, the resulting model will serve as a
flexible biosimulation platform to enhance drug development by quickly identifying
drug candidates that are likely to be associated with idiosyncratic hepatic toxicity,
and to guide personalized medicine by determining patient characteristics associated
with a greater likelihood of adverse liver responses.
1736 DEFINING SYSTEMS BIOLOGY IN A MODE-OF-
ACTION CONTEXT.
S. Edwards. U.S. EPA, Research Triangle Park, NC.
There are many competing definitions for the term systems biology with much of
the ambiguity originating from the revolution in molecular biology techniques at
the turn of the century. The sequencing of the human genome and advent of techniques
for monitoring transcripts, proteins, and metabolites on a global scale
opened the door for a new world of molecular systems biology. In this new era,
most definitions of systems biology contain most (if not all) of the following elements:
global measurements of biological molecules to the extent technically feasible,
dynamic measurements of key biological molecules to establish quantitative relationships
among them, and experimental designs which perturb the system in
specific ways to determine these relationships. This presentation will discuss how
this these components can be used to develop a model for disease based on an interconnected
network of molecular, cellular, and organism-level events. These disease
networks can then serve as the framework for a network-based description of
mode of action. Approaching the problem from this perspective provides a biologically-based
mechanism for incorporating other factors affecting risk such as genetic
susceptibility, life stage, and pre-existing diseases. It also enhances the ability of
more traditional biological modeling approaches to lay the groundwork for toxicity
pathway-based risk assessment. The approach will be illustrated using examples
from both human health and ecological research. [This abstract does not necessarily
reflect the view of the Environmental Protection Agency.]
1737 PHARMGKB: THE PHARMCOGENOMICS
KNOWLEDGE BASE.
T. E. Klein. Department of Genetics, Stanford University Medical Center, Stanford,
CA. Sponsor: L. Burgoon.
The mission of the PharmGKB is to collect, encode, and disseminate knowledge
about how human genetic variation affects drug response. Established in 2000,
PharmGKB has become the pre-eminent resource for pharmacogenomics information.
It was one of the first “post-genome” resources with information about both
genotype and phenotype, and has now become a focal point for data sharing. Via
literature review, the PharmGKB team curates primary data, and annotates gene
variants and gene-drug-disease relationships, The integration of genotype, phenotype,
and drug pathways allows for a systems level analysis and hypothesis generation
on new gene-drug interactions and effects.
1738 THE INTERSECTOME: INTEGRATION OF
KNOWLEDGE IN SYSTEMS BIOLOGY FOR
HYPOTHESIS GENERATION.
A. Ma’ayan. Pharmacology and Systems Therapeutics, Mount Sinai School of
Medicine, New York, NY. Sponsor: L. Burgoon.
I will discuss how we utilize data collected from the public domain, describing regulatory
interactions in mammalian cells, to analyze results from experiments that
profile cells using a variety of cutting edge genome-wide profiling technologies. The
results from our analyses produce rational hypotheses for further experimental validation
as well as provide a global view of cell regulation across multiple layers.
Specifically, I will show GATE, a program we developed for the analysis of time-series
expression data used to analyze stem cell differentiation. I will also demonstrate
Genes2Networks a program we developed and used to predict components and
pathways essential for CB1R induced neurite outgrowth of Neuro2A cells.
Genes2Networks was also used to predict a novel disease gene that causes Noonan
syndrome. Finally, I will discuss our tools KEA for the analysis of SILAC phosphoproteomics,
and ChEA for the analysis of gene expression data using a ChIP-X
database. I will conclude with a proposition of ideas about developing robust theoretical
models for candidate drug/gene/protein rankings for functional experimental
validation.
1739 INTEGRATED ANALYSIS OF DISTINCT MOLECULAR
AND PHENOTYPIC DATA TYPES IN XENOBIOTIC
RESPONSE MODELING.
R. J. Brennan. Toxicology, GeneGo Inc., San Jose, CA.
Signaling and metabolic pathways acting within and between cells in an organism
may be considered as integrated circuits working to maintain cell growth or homeostasis
based on inputs from external influences and other, connected pathways.
The components of these circuits comprise DNA, RNA, proteins, enzymatic activities,
small molecules, ions etc., and in order to fully understand the circuit, or to
“reconstruct the system” it is necessary to consider all of it’s components as well as
the connections (interactions) between them. These concepts are the basis of the
systems biology approach to biological pathway analysis and network reconstruction.
In recent years this approach has been successfully used to integrate data of
different types, and from different sources, on multiple types of circuit component
– genes, mRNA, proteins, metabolites, microRNA, to obtain a more precise and
comprehensive understanding of how disruptions to the circuitry can lead to disease
or toxicity. Gross damage to the circuitry by removal or functional impairment
of certain components may impact the functioning of the circuit. Individual differences
in the system, arising through sequence variations in the DNA template for
individual components, also may affect the response of the circuit to normal stimuli
or to xenobiotic interference. These variations manifest as different susceptibilities
to disease, responses to therapeutic intervention or risks of chemical toxicity.
The integration of data on the functional consequences of sequence variation to the
systems biology circuit model will be critical to complete understanding of system
malfunction or failure in disease or toxicity, and to the successful implementation
of personalized medicine.
1740 ZEBRAFISH: A PREDICTIVE MODEL FOR ASSESSING
CANCER DRUG-INDUCED ORGAN TOXICITY.
L. D’Amico 1 , C. Li 1 , E. Glaze 2 , M. Davis 2 and W. L. Seng 2 . 1 Phylonix,
Cambridge, MA and 2 NCI, NIH, Bethesda, MD. Sponsor: P. McGrath.
Toxic effects of 4 cancer compounds on CNS, heart, liver, and kidney were visually
assessed in live, transparent zebrafish and compared to effects in mammals and humans.
Compounds, tested blinded, included: 1) 17-DMAG, an HSP90 inhibitor
in Phase I clinical trials for lymphoma, 2) paclitaxel, a microtubule stabilizer approved
for breast cancer, 3) SMA-838, a transcriptional inhibitor, and 4) zebularine,
a DNA methyltransferase inhibitor which has exhibited antitumor effects in
preclinical studies. After adding compounds directly to fish water, LC10 and LC50
were estimated and 6 concentrations below LC10 were then used to treat 2 or 4 day
post fertilization zebrafish. Results showed that 17-DMAG induced defects in zebrafish
CNS, heart, liver, and kidney and cell death in CNS, heart, and liver. In
comparison, in rat and dog studies, only liver specific toxicity was observed. Similar
to results in zebrafish, human clinical trial data showed that 17-DMAG induced
CNS, heart, liver and kidney toxicity. Due to low solubility, at concentrations up to
2 μM, paclitaxel, induced CNS toxicity, similar to data reported in human clinical
trials. In contrast, in rats, no toxicity was identified in test organs. SMA838 caused
both morphological defects and cell death in zebrafish CNS and liver. In comparison,
in rats, no toxicity was observed in test organs. However, dog studies identified
liver and kidney toxicity. No toxicity was observed in zebularine treated zebrafish,
similar to results in preclinical studies. This small targeted study highlights the utility
of using transparent zebrafish for assessing drug induced organ toxicity eliminating
the need for surgical procedures. Advantages of using zebrafish as an animal
model for assessing drug induced toxicity include: small amount of drug required,
easy drug treatment directly in the fish water, short treatment time, visual assessment
in transparent animals without the need for surgery and laborious processing,
statistically significant number of animals per test, and low cost.
1741 MANIPULATION OF THE WNT/β-CATENIN PATHWAY
BY PROTOTYPIC INHIBITORS COMPARED TO
MORPHOLINO KNOCKDOWN IN ZEBRAFISH.
S. M. Eddy, D. B. Stedman and M. D. Aleo. Drug Safety, Pfizer Global Research
and Development, Groton, CT.
Manipulation of the Wnt/β-Catenin signaling pathway can be demonstrated in
Zebrafish (ZF) by treatment with prototypic inhibitors or Morpholino knock
down of TCF4 or β-Catenin. Expression analysis following treatment with prototypic
compounds FH535, IWR-1, XAV939, and SB415286 confirmed their effects
on the Wnt pathway. Phenotype following inhibitor treatment was compared to
that after TCF4 or β-Catenin Morpholino injection. Wild type Zf embryos were
treated with FH535, IWR-1, XAV939, and SB415286 at 6, 24, 48, and 72 hours
SOT 2011 ANNUAL MEETING 373