POLYCYCLIC AROMATIC HYDROCARBON O-QUINONES MUTATE p53 IN HUMAN LUNG ADENOCARCINOMA (A549) CELLS

Human lung adenocarcinoma (A549) cells form reactive and redox active PAH-o-quinones via constitutively expressed aldo-keto reductases. To determine whether these metabolites mutate p53, A549 cells were treated with N-methyl-N-nitroso-N-nitroguanidine (MNNG an alkylating mutagen), anti-BPDE (diol-epoxide) and benzoa]pyrene-7,8-dione (o-quinone). p53 cDNA was amplified from the treated cells and cotransfected with a gap-repair plasmid designed to express p53 in yeast. When mutant p53 is expressed, it fails to drive the expression of an ADE2 reporter, and the yeast strain yIG397 turns red. The following mutational frequencies were observed versus the solvent controls: 1 mM MNNG (24.2% red colonies p = .02), 1 μ M anti-BPDE (9.9% red colonies p = .02), and 10 μ M BP-7,8-dione (9.3% red colonies p = .03). MNNG gave a high frequency (49%) of the expected C > T (G > A) mutations (p = .25). While anti-BPDE and BP-7,8-dione gave A > G (T > C) transitions (p = .034 – p = .054). These mutations would result from stable N⁶-deoxyadenosine adducts, but not from oxidatively damaged bases.