Gene-specific formation and repair of cisplatin intrastrand adducts and interstrand cross-links in Chinese hamster ovary cells.
We have used three methods to study the formation and repair of intrastrand adducts and interstrand cross-links in the DNA of Chinese hamster ovary cells induced by the anticancer drug cis-diamminedichloroplatinum II (cisplatin). Using atomic absorption spectroscopy, we found that 21% of the total genomic cisplatin adducts were removed at 8 h and 42% at 24 h. We used ABC excinuclease digestion, coupled with out previously reported methodology to quantify DNA in specific genomic regions. These adducts were removed faster in the transcribed dihydrofolate reductase and c-myc genes compared to a noncoding fragment, a region containing the little or nontranscribed c-fos oncogene, and to the overall genome. Interstrand cross-links in specific sequences were quantified by Southern hybridization of denatured-renatured DNA separated on a neutral gel. We found that cross-links were removed more efficiently from the gene regions than intrastrand adducts and, at high levels of cross-linking, removal was similar from transcribed and from nontranscribed regions.
Jones
J C
JC
Laboratory of Molecular Pharmacology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Zhen
W P
WP
Reed
E
E
Parker
R J
RJ
Sancar
A
A
Bohr
V A
VA
D000818:Animals; D002460:Cell Line; D002945:Cisplatin / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D003432:Cross-Linking Reagents; D004247:DNA / Q000187:drug effects* / Q000302:isolation & purification; D004249:DNA Damage; D004260:DNA Repair; D005260:Female; D005796:Genes; D010053:Ovary; D011519:Proto-Oncogenes; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics
D003432:Cross-Linking Reagents; D004247:DNA; D013762:Tetrahydrofolate Dehydrogenase; D002945:Cisplatin