Caffeine inhibition of postreplication repair of N-acetoxy-2-acetylamino fluorene-damaged DNA in Chinese hamster cells.

Abstract

The effect of caffeine on Chinese hamster cells in vitro , treated with various metabolites and derivatives of 2-acetylaminofluorene, was studied at the molecular level. With the use of an alkaline sucrose gradient centrifugation technique, parental and newly synthesized DNA in control and treated cells were studied in the presence and absence of caffeine. Caffeine synergistically affected only the sedimentation profiles of DNA synthesized in N -acetoxy-2-acetylaminofluorene-treated cells but not in the control cells or in cells treated with the various derivatives of 2-acetylaminofluorene. N -Acetoxy-2-acetylaminofluorene also affected the sedimentation profiles of parental DNA, but caffeine did not influence this effect. At the dose level used, caffeine had no apparent effect on the incorporation of thymidine into DNA in either the control or N -acetoxy-2-acetylaminofluorene-treated cells. These results supplement other reports that suggest that the N -acetoxy-2-acetylaminofluorene lesion in DNA of either human or Chinese hamster cells is repaired similarly to ultraviolet light-induced pyrimidine dimers.