Oxidation of DNA bases by XXXX promoter-activated processes.

@entity274 @entity45057 @entity55420 @entity72389 @entity5 @entity26 @entity3014 @entity3015 @entity865 @entity1014 @entity35 @entity864 @entity3457
Evidence has accumulated showing that active @entity26 species participate in at least one stage of @entity5 promotion. Tumor promoters can induce various types of cells to undergo processes that result in formation of active @entity26 species. They stimulate polymorphonuclear leukocytes (PMNs) to undergo an oxidative burst that is characterized by rapid formation of .O2- and @entity274 . We find that in vitro formation of @entity274 by @entity5 promoter-activated PMNs correlates with their in vivo first-stage promoting activity. Moreover, two @entity1014 derivatives are formed in DNA coincubated with @entity5 promoter-stimulated PMNs: @entity45057 ( @entity55420 ) and @entity72389 (dTG). The amounts of @entity55420 and dTG formed correlate with the first-stage @entity5 -promoting potencies of the agents used for PMN stimulation and with the amount of @entity274 generated. We find that @entity55420 is also formed in the DNA of HeLa cells coincubated with @entity864 ( @entity865 )-activated PMNs, with the amount of @entity55420 being proportional to that of @entity865 used. Even in the absence of PMNs, @entity55420 is increasingly formed in cellular DNA with increased @entity865 concentration, although at much lower levels than in the presence of PMNs. When @entity35 liver microsomes are incubated with @entity3014 ( @entity3015 ), a complete carcinogen, @entity274 is also generated. Production of @entity274 increases linearly with increasing concentrations of @entity3015 . Furthermore, @entity55420 is formed in DNA exposed to @entity3015 -treated microsomes, and its formation is inhibited by catalase. These results suggest that carcinogen-induced processes generating @entity274 are associated with the first-stage promoting @entity3457 .
