The Enhanced Repair of O 6-Alkylguanine in Mammalian Systems

The “adaptive” response in bacteria may be defined in terms of a reduction in the toxicity and mutagenicity of certain agents by pre-exposure to low levels of the agent and the effect is intimately associated with an enhanced DNA repair process1,2,3. In mammals it is premature to conclude that an equivalent system exists since none of these parameters have been examined simultaneously but there are now a number of systems in which pretreatment with various carcinogenic agents has been shown to enhance the capacity of certain tissues to repair O6-alkylguanine lesions in DNA. These systems are outlined here and the possible relationship of this phenomenon to carcinogenicity is considered.