Comparative oncogenic activation of 7H-dibenzo[c,g]carbazole and dibenze[a,j]acridine

7H-Dibenzo[c,g]carbazole (DBC) is a potent liver, lung and skin carcinogen while dibenz[a,j]acridine (DBA) is a moderate skin carcinogen. DEC is metab olized to phenols and DBC-DNA adducts are formed through the 2-, 3-, and 4- phenols or directly through radical cations. Mutations in ras as a result o f DEC, activation are found exclusively in codon 61 in liver, lung and skin . DBA is metabolized to dihydrodiols, and phenols and DBA-DNA adducts are f ormed through the diol-epoxides and possibly through bis-diol-epoxides. Mut ations in ras, as a result of DBA activation, are found in codons 12, 13, a nd 61. These results indicate that although the two compounds are structura lly similar, differing by one carbon in the middle ring, there are differen ces in their metabolism, DNA binding, mutational spectra and target-organ c arcinogenesis.