Characterizing and predicting carcinogenicity and mode of action using conventional and toxicogenomics methods

Area of Science:

• Toxicology and Molecular Biology
• Cancer Research
• Genomics

Background:

• Carcinogen classification is crucial for cancer risk assessment, yet distinguishing genotoxic from nongenotoxic mechanisms remains challenging.
• Nongenotoxic carcinogens complicate established relationships between genotoxicity and carcinogenicity, impacting the interpretation of rodent study results for human relevance.
• While nongenotoxic rodent carcinogens have increased, most known human carcinogens are detected by genotoxicity tests.

Purpose of the Study:

• To evaluate the potential of predictive toxicogenomics for classifying genotoxic and nongenotoxic carcinogens.
• To assess the utility of molecular expression analysis in predicting the carcinogenicity of untested chemicals.
• To explore how gene expression profiles reflect underlying modes of action in carcinogenesis.

Main Methods:

• Review of predictive toxicogenomics investigations over the past six years.
• Analysis of global molecular expression data from genomic perturbation.
• Correlation of gene expression profiles with toxicological outcomes, including carcinogenicity.

Main Results:

• Molecular expression analysis shows promise in accurately classifying genotoxic and nongenotoxic carcinogens.
• Gene expression profiles can predict the carcinogenicity of chemicals not yet tested.
• Distinct gene expression patterns, such as DNA damage response and cell cycle progression, indicate different modes of action.

Conclusions:

• Predictive toxicogenomics offers a powerful tool for improving carcinogen classification and risk assessment.
• Gene expression profiles reflect underlying mechanisms of action, aiding in the prediction of chemical carcinogenicity.
• Integrating toxicogenomics with conventional genotoxicity tests enhances the prediction of chemical carcinogenicity.