Gene expression profiling in primary mouse hepatocytes discriminates true from false-positive genotoxic compounds

Area of Science:

• Toxicology
• Genetics
• Molecular Biology

Background:

• Established in vitro genotoxicity assays exhibit high false-positive rates for predicting in vivo outcomes.
• A need exists for more accurate in vitro methods to assess chemical genotoxicity and carcinogenicity.
• Distinguishing true genotoxic (GTX) from false-positive genotoxic (FP-GTX) compounds is crucial for chemical safety assessment.

Purpose of the Study:

• To evaluate gene expression profiling in primary mouse hepatocytes for discriminating true GTX from FP-GTX compounds.
• To develop a reliable in vitro assay for predicting in vivo genotoxicity and carcinogenicity.
• To identify gene expression signatures associated with true genotoxicity.

Main Methods:

• Primary mouse hepatocytes were treated with known GTX and FP-GTX compounds.
• Whole genome gene expression was analyzed using Affymetrix microarrays.
• Hierarchical clustering and prediction analysis of microarray (PAM) were employed for classification.

Main Results:

• A classification model achieved 100% accuracy at 24 hours and 80% at 48 hours in validation.
• Classifiers were primarily associated with metabolic, biosynthetic, immune, and apoptotic pathways.
• Incorporating DNA damage markers (γH2AX foci) did not enhance classification accuracy.

Conclusions:

• Gene expression profiling in primary mouse hepatocytes effectively differentiates true GTX from FP-GTX compounds.
• This approach provides a more reliable in vitro alternative to conventional genotoxicity assays.
• The findings support the use of transcriptomics for improved chemical safety evaluations.