Genotoxicity of 1‐methylpyrene and 1‐hydroxymethylpyrene in chinese hamster V79‐derived cells expressing both human CYP2E1 and SULT1A1

1‐Methylpyrene (1‐MP) is a widespread pollutant that is carcinogenic in animals following metabolic activation. Previous studies have shown that benzylic hydroxylation of 1‐MP, catalyzed by multiple CYP isoforms, gives rise to 1‐hydroxymethylpyrene (1‐HMP), which becomes bioreactive following further metabolism by various sulfotransferase (SULT) isoforms. However, the mutagenic and chromosome damaging effects of 1‐MP and 1‐HMP in mammalian cells have not been investigated. In this study a Chinese hamster V79‐derived cell line expressing both human CYP2E1 and human SULT1A1 was used to investigate the ability of 1‐MP and 1‐HMP to induce cytotoxicity (using the CCK‐8 assay), micronuclei and Hprt gene mutations. The role of each enzyme was investigated through co‐exposure in the presence of an enzyme inhibitor. We found that at concentrations of 0.5–4 μM and 5–20 μM, under conditions where no reduction in cell viability/growth occurred, 1‐HMP and 1‐MP induced micronuclei in V79‐hCYP2E1‐hSULT1A1 cells in a concentration‐dependent manner; however, both compounds were inactive in V79 cells. Similarly, they both caused an increase in Hprt mutant frequency in V79‐hCYP2E1‐hSULT1A1 cells in these concentration ranges, with 1‐MP impairing cell viability/growth at 10 μM and above in the mutagenicity assay. The compounds were again both inactive in V79 cells. The effects of 1‐HMP in V79‐hCYP2E1‐hSULT1A1 cells were blocked or reduced by addition of pentachlorophenol (PCP), a SULT1 inhibitor; the genotoxicity of 1‐MP was significantly reduced by either 1‐aminobenotrazole, a CYP2E1 inhibitor, or PCP. The results suggest that human CYP2E1 and SULT1A1 cooperate to activate 1‐MP and cause genotoxicity in mammalian cells. Environ. Mol. Mutagen. 56:404–411, 2015. © 2014 Wiley Periodicals, Inc.