title: Caffeine inhibits excision of 7-bromomethylbenz (a) anthracene-DNA adducts from exponentially growing but not from stationary phase Chinese hamster cells.
abstract: Excision of 7-bromomethylbenz(a)anthracene (7-BMBA)-DNA adducts from exponentially growing cultures of Chinese hamster V79-379A cells followed logarithmic kinetics with a half of approximately 20 hrs. Post-treatment incubation in the presence of a sub-toxic concentration of caffeine markedly reduced this loss. Caffeine brought about a concomitant increase in overall DNA synthetic rate in treated exponential cultures. Excision in stationary, non-DNA-replicating cultures, was slower and caffeine did not affect this reduced rate of excision. These findings lend support to a previous proposition that the caffeine-induced inhibition of elongation of nascent DNA on a template containing chemical lesions results in an interference with the excision repair mechanism that removes these lesions.
mesh_terms: D000818:Animals; D001551:Benz(a)Anthracenes; D002110:Caffeine / Q000494:pharmacology*; D002455:Cell Division; D002460:Cell Line; D006224:Cricetinae; D004247:DNA / Q000302:isolation & purification / Q000378:metabolism*; D004261:DNA Replication / Q000187:drug effects; D007700:Kinetics
chemical_list: D001551:Benz(a)Anthracenes; D002110:Caffeine; D004247:DNA