Gene expression profiling reveals multiple toxicity endpoints induced by hepatotoxicants.

Area of Science:

• Toxicogenomics
• Drug Development
• Molecular Toxicology

Background:

• Microarray technology is increasingly used in pharmaceutical toxicology and safety assessment.
• Hepatotoxicity is a common clinical liability associated with pharmaceutical agents.
• Distinguishing between different types of drug-induced liver injury is crucial for safety assessment.

Purpose of the Study:

• To investigate gene expression changes associated with specific types of drug-induced hepatotoxicity.
• To define gene expression profiles capable of distinguishing between different hepatotoxic agents and endpoints.
• To explore the utility of expression profiling in predicting toxicological outcomes and understanding toxicity mechanisms.

Main Methods:

• Oral administration of benchmark hepatotoxicants (acetaminophen, methotrexate, methapyrilene, furan, phenytoin) to Sprague-Dawley rats.
• Assessment of hepatic gene expression using toxicology-specific microarrays (684 target genes/ESTs).
• Analysis of gene expression data using Principal Component Analysis (PCA) and multiplicity-adjusted permutation tests.

Main Results:

• Principal Component Analysis (PCA) clearly distinguished gene expression profiles for each tested hepatotoxic compound.
• Significantly altered genes were identified and correlated with specific hepatotoxic endpoints, including microvesicular lipidosis, hepatocellular necrosis, inflammation, hepatitis, bile duct hyperplasia, and fibrosis.
• Repression of lipid oxidation enzymes was associated with microvesicular lipidosis.

Conclusions:

• Gene expression profiling can effectively distinguish between different hepatotoxic agents and their associated toxicological endpoints.
• Expression profiling holds potential for predicting the development of toxic endpoints.
• This approach can generate hypotheses regarding the underlying mechanisms of drug-induced toxicity.