Benzo[a]pyrene diol-epoxides: different mutagenic efficiency in human and bacterial cells

Area of Science:

• Environmental Health
• Molecular Toxicology
• Genetics

Background:

• Benzo[a]pyrene is a polycyclic aromatic hydrocarbon found in environmental pollutants.
• Benzo[a]pyrene diol-epoxides are reactive metabolites that can form DNA adducts.
• DNA adducts can lead to mutations and potentially cancer.

Purpose of the Study:

• To investigate the mutagenic effects of different enantiomers of benzo[a]pyrene diol-epoxides in human and bacterial cells.
• To compare the formation and mutagenic efficiency of DNA adducts in human fibroblasts and Salmonella typhimurium TA100.
• To determine if the structural configuration of DNA adducts influences mutation induction.

Main Methods:

• Treatment of human fibroblasts and S. typhimurium TA100 with [3H]-labelled benzo[a]pyrene diol-epoxide enantiomers.
• Quantification of mutant resistant cells (6-thioguanine in human, 8-azaguanine in bacteria).
• Characterization of DNA adducts using High-Performance Liquid Chromatography (HPLC).

Main Results:

• All tested enantiomers induced mutations in both human and bacterial cells.
• Similar DNA adduct species were identified in both cell types for the same enantiomers.
• Mutagenic efficiency of specific adducts differed significantly between human (hprt locus) and bacterial (gpt locus) systems, with opposite trends observed.

Conclusions:

• The structural configuration of DNA adducts is crucial for determining mutagenic outcomes.
• Human and bacterial cells exhibit distinct specificities in processing benzo[a]pyrene diol-epoxide adducts.
• These findings contribute to understanding the mechanisms of chemical mutagenesis and genotoxicity.