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Methapyrilene toxicity: anchorage of pathologic observations to gene expression alterations
Hisham K Hamadeh1, Brian L Knight, Astrid C Haugen
1National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
Abstract:
Methapyrilene (MP) exposure of animals can result in an array of adverse pathological responses including hepatotoxicity. This study investigates gene expression and histopathological alterations in response to MP treatment in order to 1) utilize computational approaches to classify samples derived from livers of MP treated rats based on severity of toxicity incurred in the corresponding tissue, 2) to phenotypically anchor gene expression pattems, and 3) to gain insight into mechanism(s) of methapyrilene hepatotoxicity. Large-scale differential gene expression levels associated with the exposure of male Sprague-Dawley rats to the rodent hepatic carcinogen MP for 1, 3, or 7 days after daily dosage with 10 or 100 mg/kg/day were monitored. Hierarchical clustering and principal component analysis were successful in classifying samples in agreement with microscopic observations and revealed low-dose effects that were not observed histopathologically. Data from cDNA microarray analysis corroborated observed histopathological alterations such as hepatocellular necrosis, bile duct hyperplasia, microvesicular vacuolization, and portal inflammation observed in the livers of MP exposed rats and provided insight into the role of specific genes in the studied toxicological processes.
Insights
Methapyrilene (MP) exposure causes liver damage in rats. Gene expression analysis revealed toxicity patterns and mechanisms, identifying low-dose effects not seen in traditional pathology.
Area of Science:
- Toxicology
- Genomics
- Computational Biology
Background:
- Methapyrilene (MP) is a known rodent hepatotoxin.
- Hepatotoxicity manifests as diverse pathological responses in the liver.
Purpose of the Study:
- Classify MP-induced liver toxicity severity using computational methods.
- Correlate gene expression patterns with histopathological findings.
- Elucidate the mechanisms underlying methapyrilene hepatotoxicity.
Main Methods:
- Exposure of male Sprague-Dawley rats to MP (10 or 100 mg/kg/day) for 1, 3, or 7 days.
- Monitoring of large-scale differential gene expression using cDNA microarray analysis.
- Application of hierarchical clustering and principal component analysis for sample classification.
Main Results:
- Computational approaches successfully classified samples based on toxicity severity, aligning with histopathology.
- Gene expression analysis revealed low-dose MP effects undetectable by histopathology.
- Microarray data confirmed histopathological findings like necrosis, bile duct hyperplasia, and inflammation, and identified key genes involved.
Conclusions:
- Gene expression profiling combined with computational analysis provides a sensitive method for assessing chemical-induced liver toxicity.
- MP exposure induces specific gene expression changes that correlate with observed pathological alterations.
- This study offers insights into the molecular mechanisms of methapyrilene-induced hepatotoxicity.