Enhanced excision repair of DNA damage due to cis-diamminedichloroplatinum(II) in resistant cervix carcinoma HeLa cells.
We have previously reported a cisplatin-resistant HeLa cell line which exhibits overproduction of nuclear proteins preferential for cisplatin-modified DNA (Chao et al., Cancer Res. 51:601-605, 1991; Biochem. J. 277: 875-878, 1991). In this study, excision repair of cisplatin-DNA adducts in a resistant and a revertant cell lines was investigated using in situ detection of cisplatin-DNA adducts by an immunoassay and the measurement of repair-associated DNA strand breaks by a sensitive alkaline elution method. The resistant cells exhibited a 2-fold decrease in the accumulation of cisplatin-DNA adducts; whereas, the revertant cells showed a similar level of cisplatin-DNA adducts as the parental cells in the parallel experiment. Immediately following cisplatin treatment, the resistant and the revertant cells accumulated respectively approximately 50% and 90% cisplatin-DNA adducts of the parental cells. However, the kinetic patterns of repair rate following peak accumulation of cisplatin-DNA adducts (which took approximately 4 h) was the same in the three cell lines. This finding was supported by the measurement of repair-associated DNA strand breaks using alkaline elution which showed 1.6- and 1.5-fold increase in the resistant and the revertant cells respectively. In addition, following transfection with plasmid DNA carrying cisplatin damage, the resistant and the revertant cells displayed a 2.4- and 1.4-fold enhancement in host cell reactivation, respectively. Furthermore, the acquired resistance in HeLa cells was partially reversed by nontoxic aphidicolin, a DNA polymerase-alpha and DNA repair inhibitor. The results strongly suggest the improved excision repair of cisplatin-DNA adducts as a mechanism of phenotypic resistance of cells to cisplatin.
Chao
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Department of Biochemistry, Chang Gung Medical College, Taoyuan, Taiwan, ROC.
D000911:Antibodies, Monoclonal / Q000276:immunology; D002470:Cell Survival / Q000187:drug effects; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D002945:Cisplatin / Q000378:metabolism* / Q000494:pharmacology*; D018736:DNA Adducts / Q000378:metabolism*; D004249:DNA Damage / Q000502:physiology*; D004260:DNA Repair / Q000502:physiology*; D004351:Drug Resistance; D004797:Enzyme-Linked Immunosorbent Assay; D006367:HeLa Cells; D006801:Humans; D014162:Transfection
D000911:Antibodies, Monoclonal; D018736:DNA Adducts; C057270:cisplatin-DNA adduct; D015500:Chloramphenicol O-Acetyltransferase; D002945:Cisplatin