Oxidative DNA damage and mutations induced by a polar photosensitizer, Ro19-8022.
The oxidative DNA damage induced by the polar photosensitizer Ro19-8022 in the presence of light was studied and correlated with the associated mutagenicity. Both in isolated DNA and AS52 Chinese hamster ovary cells, photoexcited Ro19-8022 gave rise to a DNA damage profile that was similar to that caused by singlet oxygen: base modifications sensitive to the repair endonuclease Fpg protein, which according to high-performance liquid chromatography (HPLC) analysis were predominantly 8-hydroxyguanine (8-oxoG) residues, were generated in much higher yield than single-strand breaks, sites of base loss (AP sites) and oxidative pyrimidine modifications sensitive to endonuclease III. Fifty percent of the Fpg-sensitive modifications were repaired within 2 h. Under conditions that induced 10 Fpg-sensitive modifications per 10(6) bp (six 8-oxoG residues per 10(6) bp), approximately 60 mutations per 10(6) cells were induced in the gpt locus of the AS52 cells. A rather similar mutation frequency was observed when a plasmid carrying the gpt gene was exposed to Ro19-8022 plus light under cell-free conditions and subsequently replicated in bacteria. Sequence analysis revealed that GC-->TA and GC-->CG transversions accounted for 90% of the base substitutions. A significant generation of micronuclei was detectable in AS52 cells exposed to the photosensitizer plus light as well.
Will
O
O
Institute of Pharmacy, University of Mainz, Germany.
Gocke
E
E
Eckert
I
I
Schulz
I
I
Pflaum
M
M
Mahler
H C
HC
Epe
B
B
D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002474:Cell-Free System; D006224:Cricetinae; D004249:DNA Damage; D004279:DNA, Viral / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation; D018384:Oxidative Stress; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011759:Pyrrolidines / Q000494:pharmacology*; D011807:Quinolizines / Q000494:pharmacology*
D004279:DNA, Viral; D017319:Photosensitizing Agents; D011759:Pyrrolidines; D011807:Quinolizines; C076809:Ro 19-8022