Induced reactivation of uv-damaged phage lambda in E. coli K12 host cells treated with aflatoxin B1 metabolites

The metabolism of aflatoxin B1, the most potent hepatocarcinogen so far known, promote in E. coli K12 cells the reactivation of phage lambda damaged by ultraviolet (UV) radiation. This reactivation process is error prone: 25 percent of the phage DNA lesions are reapaired, but mutagenesis, scored as clear plaque formation, is increased as much as 10-fold. Such reactivation of UV-damaged phage lambda, which occurs in wild-type and in uvrA but not in recA bacteria, is inducible: phage reactivation is obtained even after a long delay following treatment of the host by the short-lived metabolites. This induced reactivation of UV-damaged phage in hosts treated with metabolites of aflatoxin B1 is similar to direct or indirect UV reactivation. Metabolites of aflatoxin B1 produce induced phage reactivation as well as prophage lambda induction in lysogens and cell filamentation in non-lysogens. These cellular events are also triggered by DNA lesions caused by UV radiation and result from the induction of a metabolic pathway (SOS functions). We postulate that, in eucaryotes, carcinogens may induce cellular SOS functions similar to those in E. coli. Induction of such functions might be responsible for the transformation of mammalian cells