Suppressive effects of methyl methacrylate on the mutagenicity and DNA adduct formation induced by 1-nitropyrene and benzo[a]pyrene

Methyl methacrylate (MMA) is widely used as a cement in dentistry, orthopaedic surgery and ophthalmology. Studies based on short-term genotoxicity tests have produced conflicting results in the last two decades. In the present study, the effects of MMA on the mutagenicity of 1-nitropyrene (1-NP) and benzo[a]pyrene (B[a]P) were evaluated with the Salmonella typhimurium TA98 strain in the absence and presence of S9 mix. The direct-acting mutagenicity of 1-NP was markedly decreased by MMA in a dose-dependent manner. However, a low inhibitory effect of MMA on the metabolic-acting mutagenicity of B[a]P was observed. MMA did not show mutagenicity within the concentrations of 4.7–37.6 μM either with or without S9 mix. The inhibitory effect of MMA was not due to its cytotoxicity because very low and/or no cytotoxicity of MMA to S.typhimurium TA98 was observed. To confirm the antimutagenicity of MMA against 1-NP and B[a]P, a 32P-postlabelling method was used to determine whether MMA modified DNA adduct formation produced by both compounds in calf thymus DNA. MMA inhibits the formation of 1-NP- and B[a]P-DNA adducts in a dose-dependent manner. The DNA adduct of 1-NP reduced by MMA was greater than that of B[a]P. Thus, we suggested that MMA was possibly acting as an inhibitor of chemical carcinogenesis.