title: Limitations of the in vitro repair synthesis assay for probing the role of DNA repair in platinum resistance.
abstract: Several studies have implicated enhanced DNA repair in acquired platinum resistance. To better understand the mechanism of increased repair we have employed an in vitro assay using cell-free extracts from platinum sensitive and resistant murine and human cell lines. Since the platinum resistant murine cell lines used in our previous studies had shown increased repair of diaminocyclohexane(dach)-Pt-DNA adducts while one of the resistant human cell lines did not, we have measured in vitro repair synthesis on DNA damaged by (d,l)-trans-1,2-diaminocyclohexanedichloroplatinum(II) (PtCl2(dach)). The results of this assay were strongly dependent on the method used to calculate repair synthesis activity and appeared to disagree with previous estimates of repair activity in these cell lines. By one method of calculation the in vitro repair synthesis assay underestimated the ratio of repair activities in the resistant versus the sensitive murine cell lines, while by the other method the in vitro assay overestimated the ratio of repair activities in the resistant versus the sensitive human cell lines.
authors.affiliation: Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill 27599.
authors.forename: A F
authors.initials: AF
authors.lastname: Nichols
authors.forename: W J
authors.initials: WJ
authors.lastname: Schmidt
authors.forename: S G
authors.initials: SG
authors.lastname: Chaney
authors.forename: A
authors.initials: A
authors.lastname: Sancar
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis*; D004249:DNA Damage; D004260:DNA Repair; D004351:Drug Resistance; D005260:Female; D006801:Humans; D007939:Leukemia L1210; D051379:Mice; D009944:Organoplatinum Compounds / Q000494:pharmacology*; D010051:Ovarian Neoplasms; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; C013933:dichloro-1,2-diaminocyclohexane platinum complex; D004247:DNA