Interaction of chemical carcinogens with macromolecules.

The nature of certain critical cellular reactions is discussed in terms of both mutagenic and carcinogenic effects. Emphasis is placed on the ability of the ultimate carcinogen, normally formed in vivo by metabolism, to react with nucleic acids and, in particular, with nuclear DNA. The actions of N-nitroso compounds is examined in some detail and a possible correlation of the carcinogenic action of these compounds with their ability to react with oxygen-atoms in nucleic acids in considered. The formation of a specific lesion, O6-alkylguanine, in DNA and the capacity for its repair in different tissues is discussed with respect to tissue susceptibility to tumor induction. This discussion is extended to compare differences between species in the (tissue) specificity of action of particular N-nitroso compounds.