DNA-reactive carcinogens: mode of action and human cancer hazard

Area of Science:

• Toxicology
• Carcinogenesis
• Molecular Biology

Background:

• Mutagenicity is a key factor in the activity of most carcinogens.
• DNA reactivity, either direct or indirect via oxygen radicals, underlies mutagenicity.
• Understanding the sequence of events from DNA reactivity to tumor development is crucial for risk assessment.

Purpose of the Study:

• To present a model of key events linking DNA reactivity to carcinogenicity.
• To evaluate the utility of the Human Relevance Framework (HRF) for DNA-reactive chemicals.
• To assess the human carcinogenic potential of aflatoxin B1 and dichloromethane using the HRF.

Main Methods:

• Development of a set of key events for DNA-reactive chemical carcinogenicity.
• Application of the HRF to case studies of aflatoxin B1 and dichloromethane.
• Utilizing mechanistic data from in vivo and in vitro studies in animals and human cells.

Main Results:

• The HRF is a viable approach for predicting human carcinogenicity using mechanistic data.
• The HRF predicted likely human carcinogenicity for aflatoxin B1.
• The HRF suggested lower human carcinogenic potential for dichloromethane compared to rodents, aligning with epidemiological data.

Conclusions:

• The HRF successfully integrates mechanistic data for predicting human cancer risk from DNA-reactive agents.
• The framework provides a robust method for extrapolating animal and in vitro data to human health.
• Case studies demonstrate the HRF's utility in differentiating carcinogenic potential across species and chemicals.