Diverse chemical carcinogens fail to induce G1 arrest in MCF-7 cells

The effect of three reactive potent chemical carcinogens on the passage of MCF-7 cells through the cell cycle was investigated. While these cells, which express wild-type p53, were arrested in G1 after treatment with actinomycin D (a positive control), treatment with anti-benzo[a]pyrene dihydrodiol epoxide, N-acetoxy-N-2-fluorenylacetamide or N-methyl-N′-nitro-N-nitrosoguanidine, at doses consistent with survival of significant numbers of cells, caused the cells to accumulate in S phase, with little increase in those in G1. This property of these three reactive potent carcinogens, of diverse chemical types, to induce evasion of G1 arrest (the stealth property) presumably increases the likelihood of malignant change, because DNA replication continues on a damaged template. This stealth characteristic may be a major contributor to the tumorigenicity of DNA-adducting chemical carcinogens in general.